METHODS OF MAKING POROUS CRYSTALLINE MATERIALS AND THEIR USE IN HYDROCARBON SORPTION

The present invention relates to a hydrothermally stable form of a porous crystalline material useful in applications where sorbing hydrocarbons is desired. Among such applications is sorption of hydrocarbons from an exhaust stream from an engine in a cold-start condition. A hydrocarbon sorption apparatus including the hydrothermally stable porous crystalline material is provided. In either case, the hydrothermally stable porous crystalline material can contain both 10- and 12-membered ring pore channels, or alternately an 11-membered ring pore channel, as well as have one or more other properties.

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Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional U.S. Ser. Nos. 62/141,351, filed Apr. 1, 2015, and 62/063,615, filed Oct. 14, 2014, the entire contents of each of which are expressly incorporated by reference herein.

This application is also related to the U.S. non-provisional application claiming priority to provisional U.S. Ser. No. 62/063,615, filed on even date herewith.

FIELD OF THE INVENTION

The invention relates generally to the use of porous crystalline materials to sorb hydrocarbons from engine exhaust gases during cold-start conditions.

BACKGROUND OF THE INVENTION

Vehicles equipped with a conventional three-way catalytic converter typically contain a supported catalyst comprising one or more precious metals. Typically, fresh catalysts start to operate at about 170° C., while aged catalysts work only at about 200° C. to 225° C. These catalysts usually require at least 1-2 minutes to reach such temperatures, and during this “cold start” period, about 70-80% of the tailpipe hydrocarbon emissions can occur.

A number of published patent applications and patents describe the use of porous crystalline materials of various kinds and in various arrangements to sorb hydrocarbons and other pollutants from the gas stream exhausted from an internal combustion engine during the cold start period.

Important characteristics for such a hydrocarbon sorbent are the sorption capacity of the sorbent, the desorption temperature at which sorbed hydrocarbons are desorbed, e.g., for passing on to a further treatment such as catalytic conversion of pollutants to their conversion products, and the hydrothermal stability of the sorbent. Certain zeolites have been found to be useful as hydrocarbon sorbents.

SUMMARY OF THE INVENTION

In one aspect, the invention can be embodied as a hydrocarbon sorption apparatus comprising a bed of porous crystalline material containing both 10- and 12-membered ring pore channels, or alternately containing an 11-membered ring pore channel, wherein the porous crystalline material can exhibit one or more of the following properties: (i) a decrease in micropore volume no more than about 15% after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least 1.3 wt %, e.g., at least 1.5 wt % or at least 1.7 wt %; (iii) an monovalent metal cation content of 1.0 wt % or less, e.g., 0.2 wt % or less; (iv) a content of ammonium ions (NH4+) of at least 0.1%, at least 0.2%, at least 0.3%, at least 0.5%, at least 0.7%, at least 1.0%, at least 1.2%, at least 1.5%, at least 1.8%, at least 2.0%, at least 2.5% or at least 3%; and (v) a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least 0.1%, at least 0.2%, at least 0.3%, at least 0.5%, at least 0.7%, at least 1.0%, at least 1.2%, at least 1.5%, at least 1.8%, at least 2.0%, at least 2.5% or at least 3%.

The present invention can additionally or alternately be embodied as a method of treating a cold-start engine exhaust stream comprising hydrocarbons and/or other pollutants, comprising a) flowing the exhaust gas stream over a bed of a porous crystalline material, the porous crystalline material containing both 10- and 12-membered ring pore channels, or alternately containing an 11-membered ring pore channel. Such contacting of the exhaust gas stream can advantageously provide a first treated exhaust stream having lower total hydrocarbon content than that of the exhaust gas stream. The porous crystalline material used in methods of the invention can advantageously exhibit or more of the following properties: (i) a decrease in micropore volume no more than about 15% after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least about 1.3 wt %, e.g., at least about 1.5 wt % or at least about 1.7 wt %; (iii) an monovalent metal cation content of about 1.0 wt % or less, e.g., about 0.2 wt % or less; (iv) a content of ammonium ions (NH4+) of at least about 0.1%, at least about 0.2%, at least about 0.3%, at least about 0.5%, at least about 0.7%, at least about 1.0%, at least about 1.2%, at least about 1.5%, at least about 1.8%, at least about 2.0%, at least about 2.5%, or at least about 3%; and (v) a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least about 0.1%, at least about 0.2%, at least about 0.3%, at least about 0.5%, at least about 0.7%, at least about 1.0%, at least about 1.2%, at least about 1.5%, at least about 1.8%, at least about 2.0%, at least about 2.5%, or at least about 3%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows hydrocarbon sorption characteristics of the porous crystalline material of Example 6.

FIG. 2 shows hydrocarbon desorption characteristics of the porous crystalline material of Example 6.

 DESCRIPTION OF THE EMBODIMENTS

The subject matter of this application is described generally in respect to embodiments utilizing porous crystalline materials having a framework structure including pore channels involving 10-membered ring structures, pore channels involving 12-membered ring structures, or advantageously pore channels involving a combination of 10- and 12-membered ring structures. However, such description in this application can additionally or alternatively be applied to porous crystalline materials having a framework structure including pore channels involving 11-membered ring structures. In cases where the porous crystalline materials have interconnected pore networks, such as orthogonally connected in more than one dimension (e.g., in at least two dimensions and/or in three dimensions), it can be advantageous that there be a combination of at least one 10-membered ring pore channel and at least one 12-membered ring pore channel and/or that there be a combination of at least one 11-membered ring pore channel with at least one 10-membered ring pore channel and/or at least one 12-membered ring pore channel. Examples of such advantageous at least two dimensional porous crystalline materials can include so-called “12, 12, 10” materials, “12, 10, 10” materials, “11, 10, 10” materials, and “11, 10/12, 10/12 sinusoidal” materials.

The pore pathways of the materials along any one or more of the a, b, and c crystallographic axes may be linear, sinusoidal, or may take some other path. Materials that may be used can also include mesoporous materials exhibiting long-range atomic order, but that might exhibit an X-ray diffraction pattern that is not well-resolved and/or that shows some (or even only) relatively broad peaks. Therefore, both zeolites and non-zeolitic mesoporous materials may qualify as porous crystalline materials herein.

Also described herein are apparatuses and methods of sorbing hydrocarbons and/or other pollutants from an exhaust gas stream from an engine or combustion device, for example a cold-start engine exhaust stream, so as to produce a first treated exhaust stream having a lower levels of pollutants than the feed exhaust stream. The methods and apparatuses can employ as a sorbent a porous crystalline material, e.g., comprising MCM-68, which has been prepared in a manner to exhibit hydrothermal stability (and/or in a manner to improve on an otherwise relatively poor hydrothermal stability). In some embodiments, the hydrocarbon sorbent described herein can be located upstream of a catalytic converter for converting the pollutants contained in the first exhaust stream to conversion products and can provide a treated exhaust stream, e.g., that can be discharged into the atmosphere. It should be understood that, prior to discharge from the system (e.g., into the atmosphere), the treated exhaust stream can be flowed through a muffler or other sound reduction apparatus, as well known in the art.

Hydrocarbon sorption applications can include situations in which the sorbed hydrocarbons can be released substantially without conversion at some desired time and/or under some desired condition, such as sequestration and/or repurposing.

An engine can be an internal combustion engine or a turbine engine.

Hydrocarbon Sorption Apparatus

When an engine is started up, exhaust gases are produced from the combustion of a hydrocarbon fuel. The engine may be a jet engine, a gas turbine, an internal combustion engine (e.g., an automobile, truck, or bus engine), or the like. Exhaust gases produced from the combustion of a hydrocarbon fuel contain a plurality of combustion components, typically including linear and branched chain non-aromatic hydrocarbons, cycloaliphatic hydrocarbons, aromatic hydrocarbons, polycyclic hydrocarbons and mixtures thereof, as well as non-hydrocarbon components such as carbon dioxide, water, nitrogen oxides and sulfur dioxide. Compounds that can be included within such emissions include aromatic hydrocarbons such as toluene, xylene, benzene and mixtures thereof; linear and branched hydrocarbons such as methane, ethane, ethylene, propane, propylene, butane, pentane, hexane, heptane, octane; cycloaliphatic hydrocarbons such as cyclohexane; and additional fuel additives such as alcohols and methyl tertiary butyl ether. The method of the invention may be advantageously utilized to reduce such emissions, including hydrocarbon emissions, particularly during cold start operation of an internal combustion engine, without being necessarily limited to a particular hydrocarbon fuel. Typical hydrocarbon fuels used in applications benefiting from the present invention include gasoline, diesel fuel, aviation fuel, and the like.

At startup of an engine, a pollution control device can typically operate at ambient temperatures, which can range from well below 0° C. to about 45° C. Catalysts for converting pollutants to conversion products can often be inefficient in the conversion reactions until they reach a temperature from about 150° C. to about 230° C. A number of approaches have been used to raise the temperature of conversion catalysts at startup; one approach being to allow exhaust gases flowing over a conversion catalyst to warm it. The temperature of an engine exhaust stream can be relatively cool, generally below about 500° C. and typically in the range from about 200° C. to about 400° C. This engine exhaust gas stream can have the above characteristics during the initial period of engine operation, typically for the first ˜30-120 seconds after startup of a cold engine. Accordingly, a period of time from up to ˜120 seconds, or perhaps up to ˜180 seconds, and advantageously starting at ˜5 seconds, ˜10 seconds, or ˜30 seconds, after startup (the so-called “cold start period”) can be required for a pollutant conversion catalyst to reach a temperature at which it is reasonably efficient at promoting a conversion reaction.

An engine exhaust gas stream can typically contain from about 500 vppm to about 1000 vppm of hydrocarbons.

In the apparatuses and methods described herein, an engine exhaust gas stream to be treated can be flowed over a bed of porous crystalline material comprising both 10- and 12-membered ring pore channels, or alternately comprising an 11-membered ring pore channel, and the porous crystalline material can have one or more of the following characteristics:

    • (i) a decrease in micropore volume no more than about 15%, such as no more than about 12.5 wt %, or of no more than about 11 wt %, or of no more than about 10 wt %, or of no more than about 9 wt %, or of no more than about 8%, after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours;
    • (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least 1.3 wt %, e.g., at least 1.5 wt % or at least 1.7 wt %;
    • (iii) a monovalent metal cation content of 1.0 wt % or less, such as 0.5 wt % or less, or 0.25 wt % or less, or 0.2 wt % or less, or 0.1 wt % or less of the porous crystalline material;
    • (iv) a content of ammonium ions (NH4+) of at least 0.1 wt %, at least 0.2 wt %, at least 0.3 wt %, at least 0.5 wt %, at least 0.7 wt %, at least 1.0 wt %, at least 1.2 wt %, at least 1.5 wt %, at least 1.8 wt %, at least 2.0 wt %, at least 2.5 wt % or at least 3 wt %; and
    • (v) a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least 0.1 wt %, at least 0.2 wt %, at least 0.3 wt %, at least 0.5 wt %, at least 0.7 wt %, at least 1.0 wt %, at least 1.2 wt %, at least 1.5 wt %, at least 1.8 wt %, at least 2.0 wt %, at least 2.5 wt % or at least 3 wt %.

The flowing step can advantageously provide a first treated exhaust stream having a lower total hydrocarbon content than that of the feed exhaust gas stream. The lowering of the hydrocarbon content can be to a level where substantially no hydrocarbons remain in the exhaust gas stream. In additional or alternative embodiments, the hydrocarbon content can be lowered to a level that is as little as about 10 wt % of the original hydrocarbon content of the exhaust gas stream, for instance as little as about 5.0 wt %, as little as about 2.5 wt %, or as little as about 1.0 wt %.

Micropore volume as referred to above can be determined by the BET method as described by S. Brunauer, P. H. Emmett, and E. Teller, J. Am. Chem. Soc., 1938, 60, 309, using nitrogen adsorption-desorption at liquid nitrogen temperature. Micropore volume can be calculated using a t-plot of the BET data. More information regarding the method can be found, for example, in “Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density”, S. Lowell et al., Springer, 2004.

The elemental composition of the porous crystalline material, for example, the amount of silicon, aluminum, and monovalent metal cation(s) present, such as potassium, can be measured by standard processes known to those in the art, e.g., by digesting the sample in a solvent, such as hydrofluoric acid, and measuring atomic emission spectrometry (AES) of a sample of the digested finished porous crystalline material.

The porous crystalline material used herein can have a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least about 1.3 wt %, e.g., at least about 1.5 wt % or at least about 1.7 wt %. For instance, with respect to case c), the porous crystalline material can be MCM-68 that has a reduced SHGC compared to MCM-68 prepared as described in Elangovan et al., Microporous and Mesoporous Materials, 96: 210-215 (2006) at p. 211. The SHGC of the porous crystalline material, after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours can be at least 5% less than an SHGC of one or more of materials a), b), and c), e.g., at least about 10% less, at least about 12% less, at least about 15% less, at least about 20% less, at least about 25% less, or at least about 50% less. Though a maximum comparative reduction in SHGC is not critical, the reduction may be up to about 99%, e.g., up to about 98%, up to about 97%, up to about 95%, up to about 90%, up to about 85%, up to about 80%, up to about 75%, up to about 70%, up to about 60%, or up to about 50%.

The surface hydroxyl group content of the porous crystalline material can be determined by any appropriate means, e.g., by nuclear magnetic resonance (NMR) methods and/or by Fourier Transform InfraRed (FTIR) spectroscopic methods, such as Diffuse Reflectance FTIR.

The porous crystalline material used herein will typically have different profiles of sorption and desorption for different specific hydrocarbons and fuel additives (e.g., ethanol) or other substances present in the exhaust gas stream (e.g., water).

A “hydrophobicity index” is described in PCT Publication No. WO2000/051940, hereby incorporated by reference. A Hydrophobicity Index (H) is calculated from the ratio of mass sorption of organic compound to mass sorption of water at specific partial pressures for the two sorbates: thus Hc=Sc/Sw for cyclohexane over water and Hn=Sn/Sw for n-hexane over water. Hydrophilic porous crystalline materials can have H values of less than 1.0. Highly hydrophobic porous crystalline materials can have H values of substantially greater than 1.0. In some embodiments, porous crystalline materials useful in the present invention can have a hydrophobicity index greater than 1, such as a hydrophobicity index >10 or >100.

“Hydrocarbon selectivity” can be similar to the hydrophobicity index, but can relate to differential sorption characteristics for two different hydrocarbons, or between a hydrocarbon and ethanol or another substance that might be present in an exhaust gas stream. Selectivity of a sorbent as between two particular substances can be obtained, for example, by analysis of desorption profiles in a temperature programmed desorption experiment. The amount of a substance sorbed by a porous crystalline material can be obtained by integration of the area under the desorption curve from a saturated sample in a temperature programmed desorption experiment, and the hydrocarbon selectivity as between two substances can be obtained as the ratio of the amount of the two substances sorbed by the sample of porous crystalline material. In certain embodiments, the porous crystalline material used herein can be one having a specific total hydrocarbon sorption capacity (hydrocarbons which for this purpose can include alcohols), sorbed as wt % of the porous crystalline material, of at least about 7.0%, at least about 8.0%, at least about 9.0%, at least about 10%, at least about 11%, or at least about 12%.

A porous crystalline material according to the invention can be one having a monovalent metal cation content of 1.0 wt % or less (wt % being relative to the porous crystalline material). Monovalent metal cations can include, but are not necessarily limited to, alkali metal cations, Ag+, Cu+, and any mixtures thereof. A porous crystalline material according to the invention can have a content of Ag+ ions of less than about 0.5 wt %, of less than about 0.1 wt %, or substantially no Ag+ ions (e.g., no intentionally added Ag+ ions—relatively low levels of impurity ions may be present). A porous crystalline material used herein can have a content of Cu+ ions of less than about 0.5 wt %, of less than about 0.1 wt % or substantially no Cu+ ions (e.g., no intentionally added Cu+ ions—relatively low levels of impurity ions may be present).

A porous crystalline material having “substantially no [ ] cations” is one in which said cations introduced into the material during synthesis have been removed to a level representative of impurities, in some cases less than about 800 wppm of the porous crystalline material.

A useful porous crystalline material can have a content of ammonium ions (NH4+) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt %, or at least about 3 wt %.

A useful porous crystalline material can have a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt % or at least about 3 wt %. Examples of multivalent ions can include, but are not limited to, Ca2+, Mg2+, Fe3+, and combinations thereof.

A porous crystalline material useful in the methods and apparatuses described herein can be synthesized using a so-called “seeded prep” method, in which seed crystals of the porous crystalline material can be added to the synthesis mixture. Without being bound by any theory of the invention, one possible advantage of a seeded prep method can be that the crystals obtained from the synthesis can typically be larger and/or can have fewer defects than crystals grown without seeding the synthesis mixture. Typically, but not necessarily across the board, seeded preps can also result in faster crystallization times.

Additionally or alternately to the above-described embodiments, in the methods and apparatuses described herein, the porous crystalline material can comprise substantially no potassium cations.

Additionally or alternately to the above-described embodiments, in the methods and apparatuses described herein, the porous crystalline material can have a silicon to aluminum atomic ratio, expressed as Si/Al, from about 10 to about 25. The Si/Al ratio herein is measured for the material of interest; it is not the ratio in the inputs to synthesis of the material. In certain embodiments, the porous crystalline material can have an Si/Al ratio of about 7 or more, about 8 or more, about 9 or more, about 10 or more, about 12 or more, about 15 or more, or about 20 or more. In such embodiments, the porous crystalline material can have a Si/Al ratio of about 100 or less, about 75 or less, about 50 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 or less, or about 12 or less.

Additionally or alternately to the above-described embodiments, in the method and apparatus described herein the porous crystalline material can comprise one or more porous crystalline materials having an IZA framework type selected from the group consisting of BOG, CON, DFO, ITN, IVR, IWW, MSE, SFV, UOV, and USI and mixtures and intergrowths thereof. DAF-1 is an example of a zeolite having a DFO-type framework. ITQ-39 is an example of an ITN-type framework. ITQ-24 is an example of a zeolite having a IVR-type framework. ITW-22 is an example of an IWW-type framework, MCM-68 is an example of a MSE-type framework. SSZ-57 is an example of a SFV-type framework. IM-17 is an example of a UOV-type framework. IM-6 is an example of a USI-type framework.

Additionally or alternatively to the above-described embodiments, the porous crystalline material can comprise NU-86 and/or EMM-17.

Embodiments of the invention can be implemented using a MCM-68 as the porous crystalline material, which can comprise monovalent metal cations in an amount less than about 0.2 wt % of the porous crystalline material and can include substantially no potassium ions. Additionally or alternately, the MCM-68 utilized can include substantially no Ag+ ions. In any of these embodiments, the MCM-68 can also have an Si/Al ratio greater than about 10.

Methods for reducing the amount of monovalent metal cations, e.g., potassium cations, present in an MCM-68 porous crystalline material can be found, for example, in U.S. Provisional Application No. 62/063,615, hereby incorporated by reference for all such disclosure. Thus, in some embodiments, a sufficiently low amount of monovalent metal cations can be achieved by contacting the porous crystalline material with a solution containing ammonium ions at a temperature of at least about 50° C. to ammonium-exchange at least part of the occluded monovalent metal cations and produce a porous crystalline material having preferably no more than about 0.1 wt % of monovalent metal cations within the porous crystalline material.

An additional or alternative way to reduce the amount of monovalent metal cations present in a porous crystalline material can be to contact the porous crystalline material with steam at a temperature of at least about 300° C. to produce a steamed porous crystalline material; and contacting the steamed porous crystalline material with a solution containing ammonium ions to ammonium-exchange at least part of the monovalent metal cations in the steamed porous crystalline material to produce a treated porous crystalline material having a content of monovalent metal cations preferably no more than about 0.1 wt %.

Additionally or alternately to the above-described embodiments, in the methods and apparatuses described herein the porous crystalline material can be synthesized using a structure directing agent comprising N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dications; N,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2,3:5,6-dipyrrolidinium dications; 1,1-dialkyl-4-cyclohexyl-piperazin-1-ium cations; 1,1-dialkyl-4-alkylcyclohexylpiperazin-1-ium cations; 3-hydroxy-1-(4-(1-methylpiperidin-1-ium-1-yl)butyl)quinuclidin-1-ium cations, 3-hydroxy-1-(5-(1-methylpiperidin-1-ium-1-yl)pentyl)quinuclidin-1-ium cations, 1,1′-(butane-1,4-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-(pentane-1,5-diyl)bis(1-methyl-piperidin-1-ium) cations, 1,1′-(hexane-1,6-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidin-1-ium)tetraethyl-ammonium cations, cations obeying one or more of the following formulae, or a combination thereof:

where A is a >CR13R14 group, a >C═O group, or an >O group, where R1, R2, R3, R4, R7, R8, R9, and R10 are each independently hydrogen, a hydroxyl group, or a C1-C5 hydrocarbon chain, where R13 and R14 are each independently hydrogen, a C1-C5 hydrocarbon chain, a piperidinyl group or a pyrrolidinyl group, where R5, R6, R11, and R12 are each independently a C1-C5 hydrocarbon chain. Additional structure directing agents that might be used to make the porous crystalline materials are disclosed in U.S. Pat. Nos. 8,025,863 and 8,916,130, hereby incorporated by reference for such disclosure, as well as for additional disclosure relating to synthesis and post-synthesis treatment of porous crystalline materials.

Additionally or alternately to the above-described embodiments, in the methods and apparatuses of the invention, the porous crystalline material can be synthesized using a structure directing agent that has a single nitrogenous cation.

Additionally or alternately to the above-described embodiments, in the method and apparatus of the invention, the porous crystalline material can be synthesized using a structure directing agent that is not bicyclic and/or can be synthesized using a structure directing agent that is not tricyclic. For example, the porous crystalline material can be synthesized using a structure directing agent that comprises only one or more monocycles, and so does not include any fused rings and/or bridging rings.

Additionally or alternately to the above-described embodiments, in the methods and apparatuses described herein, the bed of the porous crystalline material can contain at least one further porous crystalline material having 10-membered ring pore channels or 12-membered ring pore channels, but not both 10-membered ring and 12-membered ring pore channels. The at least one further porous crystalline material can be a mixture of two or more, all having 10-membered ring channels, all having 12-membered ring channels, or one or more having 10-membered ring channels but not also 12-membered ring channels and one or more having 12-membered ring channels but not also 10-membered ring channels. In such methods, the at least one further porous crystalline material can include, but are not necessarily limited to, framework types comprising BEA, FAU, MFI, FER, and combinations thereof.

The sorbent bed used in the present invention can be conveniently employed in particulate form or the sorbent can be deposited onto a solid monolithic carrier. When the particulate form is desired, the sorbent can be used in the form of powders, pills, pellets, granules, rings, spheres, or the like, or combinations thereof. In the employment of a monolithic form, it can be most convenient, in certain embodiments, to employ the sorbent as a thin film or coating deposited on an inert carrier material that provides structural support for the sorbent. The inert carrier material can be any refractory material such as ceramic or metallic materials. It can be desirable that the carrier material be relatively unreactive with the sorbent and not be significantly degraded by the gas to which it is exposed. Examples of suitable ceramic materials include sillimanite, petalite, corderite, mullite, zircon, zircon mullite, spondumene, alumina-titanate, and the like, and combinations thereof. Examples of metallic materials that can serve as inert carrier material can include, for example, metals and alloys as disclosed in U.S. Pat. No. 3,920,583, hereby incorporated by reference, which can be oxidation resistant and are otherwise capable of withstanding high temperatures.

The carrier material can best be utilized in any rigid unitary configuration that provides a plurality of pores/channels extending in the direction of gas flow. Conveniently, the configuration may include or be a honeycomb configuration. The honeycomb structure can be used advantageously either in unitary form or as an arrangement of multiple modules. The honeycomb structure can advantageously be oriented such that gas flow can generally be in the same direction as the cells/channels of the honeycomb structure. For a more detailed discussion of monolithic structures, see U.S. Pat. Nos. 3,785,998 and 3,767,453, which are hereby incorporated by reference.

The porous crystalline material can be deposited onto the carrier by any convenient method well known in the art. One convenient method can involve preparing a slurry using the porous crystalline material and coating the monolithic honeycomb carrier with the slurry. The slurry can be prepared by means known in the art, such as combining the appropriate amount of the porous crystalline material and a binder with water. This resulting mixture can then be blended by using means such as sonication, milling, or the like, or combinations thereof. This slurry can be used to coat a monolithic honeycomb by dipping the honeycomb into the slurry, removing the excess slurry by draining or blowing out the channels, and heating to about 100° C. If the desired loading of porous crystalline material is not achieved, the above process may be repeated as many times as needed to achieve the desired loading.

Instead of depositing the porous crystalline material onto a monolithic honeycomb structure, one can take the porous crystalline material and form it into a monolithic honeycomb structure by means known in the art.

The sorbent may optionally contain one or more catalysts, for example catalytic metals dispersed thereon. In some embodiments, these catalysts can be capable of oxidizing hydrocarbons and carbon monoxide to carbon dioxide and water, and/or capable of reducing the nitric oxide components to nitrogen and oxygen as conversion products. Accordingly, in some embodiments, the sorbent bed can act both as a sorbent and as a catalyst.

In certain embodiments, metals that can be dispersed on the sorbent can include, but are not necessarily limited to, noble metals, e.g., platinum, palladium, rhodium, ruthenium, and mixtures thereof. In such embodiments, the desired noble metal(s) may be deposited onto the sorbent, which can act as a support, in any suitable manner well known in the art. One example of a method of dispersing the noble metal(s) onto the sorbent support can involve impregnating the sorbent support with an aqueous solution of a decomposable compound of the desired noble metal(s), drying the sorbent which has the noble metal compound dispersed on it and then calcining, e.g., in air, at a temperature of about 400° C. to about 500° C., and/or for a time of about 30 minutes to about 24 hours (such as from about 1 hour to about 6 hours). By decomposable compound in this context is meant a compound which, upon heating (e.g., in air), can yield the metal, an oxidized version of the metal (e.g., a metal oxide), or a combination thereof. Some non-limiting examples of decomposable compounds that can be used can be found in U.S. Pat. No. 4,791,091, hereby incorporated by reference. Some decomposable compounds for depositing catalytic noble metals can include, but are not limited to, chloroplatinic acid, rhodium trichloride, chloropalladic acid, hexachloroiridic (IV) acid, hexachlororuthenate, and the like, as well as combinations thereof. When present, the sorbent/catalyst can contain the noble metal(s) in an amount ranging from about 0.01 wt % to about 8 wt % of the sorbent support, e.g., from about 0.05 wt % to about 6 wt % of the sorbent support. Specifically, in the case of platinum and/or palladium, the amount can be from about 0.1 wt % to about 4 wt %, while, in the case of rhodium and/or ruthenium, the amount can be from about 0.01 wt % to about 2 wt %.

Catalytic Converter

The catalyst used to convert the pollutants in an engine exhaust gas can typically be referred to in the art as a three-component control (and/or three-way) catalyst, because it can simultaneously (i) oxidize any residual hydrocarbons present in the first exhaust stream to carbon dioxide and water, (ii) oxidize any residual carbon monoxide to carbon dioxide, and (iii) reduce any residual nitric oxide to nitrogen and oxygen. In some cases, the catalyst may not be required to convert nitric oxide to nitrogen and oxygen, e.g., when an alcohol is used as at least a portion of the fuel. In such cases, the catalyst might be alternately called an oxidation catalyst. When the temperature of the engine exhaust stream and/or the first exhaust stream is in the cold-start range, such catalysts typically do not function at very high efficiencies. Accordingly, in such conditions, a hydrocarbon sorbent comprising the porous crystalline material of the invention can be usefully employed to hold hydrocarbons until the first exhaust stream reaches a temperature under which the catalyst can operate more efficiently.

During operation, when a sorbent bed of porous crystalline material reaches a sufficient temperature, for example from about 150° C. to about 250° C., the pollutants sorbed in the bed can begin to desorb and/or can be carried by the first exhaust stream over the catalyst. This desorption can serve to regenerate the sorbent bed so that it can sorb hydrocarbons during a subsequent cold start. In such a situation, the catalyst can reach its operating temperature and can therefore be capable of fully converting the pollutants to conversion products.

The catalyst in the catalytic converter may be selected from any suitable three component control or oxidation catalyst, such as those well-known in the art. Examples of such catalysts can include, but are not limited to, those described in U.S. Pat. Nos. 4,528,279, 4,791,091, 4,760,044, 4,868,148, and 4,868,149, each of which being hereby incorporated by reference for such description. Typical three component catalysts well known in the art can be those that contain platinum and/or rhodium, optionally including palladium, while oxidation catalysts can usually contain no rhodium. Oxidation catalysts can usually contain platinum and/or palladium metal(s). Such catalysts may additionally contain promoters and/or stabilizers that can include, but need not be limited to, barium, cerium, lanthanum, nickel, iron, or the like, or combinations thereof. Noble metal promoters and stabilizers can advantageously be deposited on a support such as comprising alumina, silica, titania, zirconia, aluminosilicates, or mixtures thereof, particularly comprising at least alumina. The catalyst can be conveniently employed in particulate form or alternatively the catalytic composite can be deposited in the form of a solid monolithic carrier. The particulate and/or monolithic forms of the catalyst can be prepared as described for the sorbent herein.

Some embodiments of a catalytic converter according to the invention can include a bed of the porous crystalline material located upstream in the exhaust gas flow from a bed of a catalytic material.

Additionally or alternately to the above-described embodiments, a hydrocarbon sorption apparatus of the invention can include one or more catalysts for converting pollutants present in an engine exhaust gas stream into conversion products, e.g., as admixed with and/or as deposited on the porous crystalline material. Such catalysts can be provided in a bed separate from a bed of the hydrocarbon sorbent porous crystalline material and that is in fluid communication with the bed of hydrocarbon sorbent porous crystalline material.

Additionally or alternately to the above-described embodiments, in a hydrocarbon sorbent apparatus according to the invention, a bed of porous crystalline material can be in fluid connection with a pipe carrying exhaust gas from an engine and comprising hydrocarbons and the bed of porous crystalline material can be adapted to receive said exhaust gas from said pipe, to allow the exhaust gas to contact the bed of porous crystalline material so as to produce a treated exhaust gas having a lower content of hydrocarbons than the exhaust gas, and to allow the contacted exhaust gas to flow out of the bed of porous crystalline material.

Further additionally or alternately to the above-described embodiments, in a hydrocarbon sorption apparatus according to the invention, a bed of porous crystalline material can be in fluid connection with one or more beds comprising a catalyst for oxidizing hydrocarbons and nitrogen-containing compounds present in an exhaust gas and/or a three-way catalyst.

ADDITIONAL EMBODIMENTS

Additionally or alternatively, the present invention can include one or more of the following embodiments.

Embodiment 1

A method of treating a cold-start engine exhaust gas stream comprising hydrocarbons and/or other pollutants, the method comprising: a) flowing the exhaust gas stream over a bed of a porous crystalline material, the porous crystalline material (1) containing both 10- and 12-membered ring pore channels, or (2) containing an 11-membered ring pore channel, to provide a first treated exhaust stream having lower total hydrocarbon content than that of the exhaust gas stream, wherein the porous crystalline material exhibits one or more of the following properties: (i) a decrease in micropore volume no more than about 15%, such as no more than about 12.5 wt %, or of no more than about 11 wt %, or of no more than about 10 wt %, or of no more than about 9 wt %, or of no more than about 8%, after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least about 1.3 wt %, e.g., at least about 1.5 wt % or at least about 1.7 wt %; (iii) a monovalent metal cation content of about 1.0 wt % or less, such as about 0.5 wt % or less, about 0.25 wt % or less, about 0.2 wt % or less, or about 0.1 wt % or less of the porous crystalline material; (iv) a content of ammonium ions (NH4+) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt %, or at least about 3 wt %; and (v) a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt %, or at least about 3 wt %.

Embodiment 2

The method of embodiment 1, wherein the first treated exhaust gas stream comprises substantially no hydrocarbons up to a hydrocarbons content of 1 wt % of the exhaust gas stream.

Embodiment 3

A hydrocarbon sorption apparatus comprising a porous crystalline material bed, the porous crystalline material bed comprising a porous crystalline material (1) containing both 10- and 12-membered ring pore channels or (2) containing an 11-membered ring pore channel, wherein the porous crystalline material exhibits one or more of the following properties: (i) a decrease in micropore volume no more than about 15%, such as no more than about 12.5 wt %, or of no more than about 11 wt %, or of no more than about 10 wt %, or of no more than about 9 wt %, or of no more than about 8%, after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at milder conditions, such as a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least about 1.3 wt %, e.g., at least about 1.5 wt % or at least about 1.7 wt %; (iii) a monovalent metal cation content of about 1.0 wt % or less, such as about 0.5 wt % or less, about 0.25 wt % or less, about 0.2 wt % or less, or about 0.1 wt % or less of the porous crystalline material; (iv) a content of ammonium ions (NH4+) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt %, or at least about 3 wt %; and (v) a content of multivalent metal ions (for example divalent or trivalent metal ions) of at least about 0.1 wt %, at least about 0.2 wt %, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1.0 wt %, at least about 1.2 wt %, at least about 1.5 wt %, at least about 1.8 wt %, at least about 2.0 wt %, at least about 2.5 wt %, or at least about 3 wt %.

Embodiment 4

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of embodiment 3, wherein the porous crystalline material comprises substantially no potassium cations.

Embodiment 5

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of embodiment 3 or embodiment 4, wherein the porous crystalline material has a silicon to aluminum molar ratio of about 7 or more (e.g., about 8 or more, about 9 or more, about 10 or more, about 12 or more, about 15 or more, or about 20 or more) and/or a silicon to aluminum molar ratio of about 100 or less (e.g., about 75 or less, about 50 or less, about 40 or less, about 35 or less, about 30 or less, about 25 or less, about 20 or less, about 15 or less, or about 12 or less), for example from about 10 to about 25.

Embodiment 6

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of any of embodiments 3-5, wherein an IZA framework type of the porous crystalline material comprises one or more of BOG, CON, DFO, ITN, IVR, IWW, MSE, SFV, UOV, USI, and mixtures and intergrowths thereof, for example comprises or is an MSE framework type.

Embodiment 7

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of any of embodiments 3-6, wherein the porous crystalline material contains a metal deposited thereon comprising platinum, palladium, rhodium, ruthenium, or a mixture thereof, for example comprising platinum and palladium.

Embodiment 8

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of any of embodiments 3-7, wherein the porous crystalline material is synthesized using a structure directing agent comprising N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dications; N,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2,3:5,6-dipyrrolidinium dications; 1,1-dialkyl-4-cyclohexyl-piperazin-1-ium cations; 1,1-dialkyl-4-alkylcyclohexylpiperazin-1-ium cations; 3-hydroxy-1-(4-(1-methylpiperidin-1-ium-1-yl)butyl)quinuclidin-1-ium cations, 3-hydroxy-1-(5-(1-methylpiperidin-1-ium-1-yl)pentyl)quinuclidin-1-ium cations, 1,1′-(butane-1,4-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-(pentane-1,5-diyl)bis(1-methyl-piperidin-1-ium) cations, 1,1′-(hexane-1,6-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidin-1-ium)tetraethyl-ammonium cations, a cation satisfying one or more of the following formulae, or a combination thereof:

where A is a >CR13R14 group, a >C═O group, or an >O group, where R1, R2, R3, R4, R7, R8, R9, and R10 are each independently hydrogen, a hydroxyl group, or a C1-C5 hydrocarbon chain, where R13 and R14 are each independently hydrogen, a C1-C5 hydrocarbon chain, a piperidinyl group or a pyrrolidinyl group, where R5, R6, R11, and R12 are each independently a C1-C5 hydrocarbon chain.

Embodiment 9

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of any of embodiments 3-8, wherein the porous crystalline material bed contains at least one further porous crystalline material having 10-membered ring pore channels or 12-membered ring pore channels, but not both 10-membered ring and 12-membered ring pore channels, for example having a framework type comprising BEA, FAU, MFI, FER, or a combination or intergrowth thereof.

Embodiment 10

The method of embodiment 1 or embodiment 2, or the hydrocarbon sorption apparatus of any of embodiments 3-9, wherein the porous crystalline material comprises EMM-17, NU-86, or a mixture or intergrowth thereof.

Embodiment 11

The hydrocarbon sorption apparatus of any of embodiments 3-10, further comprising a catalytic converter.

Embodiment 12

The hydrocarbon sorption apparatus of any of embodiments 3-11, wherein the bed of porous crystalline material is in fluid connection with a pipe carrying exhaust gas from an engine and comprising hydrocarbons, and wherein the bed of porous crystalline material is adapted to receive said exhaust gas from said pipe, to allow the exhaust gas to contact the bed of porous crystalline material, and to allow the contacted exhaust gas to flow out of the bed of porous crystalline material.

Embodiment 13

The hydrocarbon sorption apparatus of any of embodiments 3-12, wherein the bed of porous crystalline material is in fluid connection with one or more beds comprising a three-way catalyst and/or a catalyst for oxidizing hydrocarbons and nitrogen-containing compounds present in an exhaust gas.

EXAMPLES Synthesis and Treatment of Porous Crystalline Materials Example 1 Synthesis of MCM-68 with N-methyl-N-butylpiperidinium

MCM-68 was made by the method disclosed in U.S. Pat. No. 8,900,548, Example 20. U.S. Pat. No. 8,900,548 is hereby incorporated by reference in its entirety and for all purposes, but particularly with respect to methods of making MSE framework type materials. The resulting solid was filtered and heated at about 400° C. in flowing dry air. The solid was then refluxed at about 100° C. in aqueous NH4NO3. The solid was then further heated at 550° C. in flowing dry air.

Example 2

MCM-68 of Example 1 was further treated in flowing steam at about 800° C. for ˜5 hours.

Example 3

MCM-68 of Example 1 was further treated in flowing steam at about 800° C. for ˜40 hours.

Example 4 Additional ion Exchange of MCM-68

MCM-68 of Example 1 was further treated in flowing steam at about 538° C. for ˜3 hours. The zeolite was then refluxed at about 100° C. in an aqueous solution of NH4NO3. The zeolite was then further heated at about 550° C. in flowing dry air.

Example 5

MCM-68 of Example 4 was further treated in flowing steam at about 550° C. for ˜16 hours.

Example 6

MCM-68 of Example 4 was further treated in flowing steam at about 800° C. for ˜5 hours.

Example 7

MCM-68 of Example 4 was further treated in flowing steam at about 800° C. for ˜40 hours.

Example 8 Synthesis of MCM-68 with a 1,1-dimethyl-4-cyclohexylpiperazinium Cation

MCM-68 was made by the method disclosed in U.S. Pat. No. 8,025,863, Example 157. U.S. Pat. No. 8,025,863 is hereby incorporated by reference in its entirety and for all purposes, but particularly with respect to methods of making MSE framework type materials. The resulting solid was filtered and heated at about 400° C. in flowing dry air. The solid was then refluxed at about 100° C. in an aqueous NH4NO3. The solid was then further heated at about 550° C. in flowing dry air.

Example 9

MCM-68 of Example 8 was further treated in flowing steam at about 550° C. for ˜16 hours.

Example 10

MCM-68 of Example 8 was further treated in flowing steam at about 800° C. for ˜5 hours.

Example 11 Synthesis of MCM-68 with N,N,N′,N′-tetratethyl-exo,exo-bicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium diiodide

MCM-68 was made by the method disclosed in U.S. Pat. No. 6,049,018, which is hereby incorporated by reference in its entirety and for all purposes, but particularly with respect to methods of making MSE framework type materials. The resulting solid was filtered and heated at about 400° C. in flowing nitrogen. The solid was then refluxed at about 100° C. in an aqueous NH4NO3. The solid was then further heated at about 550° C. in flowing dry air.

Example 12

MCM-68 of Example 11 was further treated in flowing steam at about 815° C. for ˜4 hours.

Example 13 Synthesis of EMM-17

EMM-17 was made by the method disclosed in PCT Application No. WO2013/126140, which is hereby incorporated by reference in its entirety and for all purposes, but particularly with respect to methods of making such EMM-17-type materials.

Example 14

EMM-17 of Example 13 was further treated in flowing steam at about 550° C. for ˜16 hours.

Characterization of MCM-68 Crystals Example 15 Physical Properties of MCM-68 Samples

The physical properties of MCM-68 from the Examples herein are reported in Table 1.

TABLE 1 Physical properties of MCM-68 crystals Representative Seeded crystal size Example SDA prep Si/Al K/Al from SEM (μm) Phase 1 A Yes ~10 ~0.01 ~1 MSE 4 A Yes ~10 ~0.03 ~1 MSE 8 B Yes ~23 ~0.01 ~0.1 MSE, minor dense phase 11 C No ~9 ~0.08 ~0.02-0.1 MSE

In Table 1, “K/Al” is the molar ratio of potassium cations in the porous crystalline material to aluminum in the porous crystalline material; and “Si/Al” is the molar ratio of silicon to aluminum present in the zeolite framework of the porous crystalline material.

Amounts of silicon, aluminum, and potassium present in the finished porous crystalline materials were determined using a Thermo-Jarrell Ash (TJA) IRIS™ Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) capable of determining silicon, aluminum, sodium, and potassium concentrations in catalyst type samples, such as zeolites, using multiple wavelengths for all enumerated elements except potassium.

“Representative Crystal Size” in Table 1 was determined from SEM images focusing on a single crystal or a small group of crystals. This number may not necessarily be the average size of crystals in the sample nor is it necessarily reflective of the distribution of crystal sizes in the sample.

A sample (from about 0.05 grams to about 0.15 grams) was weighed and transferred to a CEM Teflon® digestion vessel. Hydrofluoric acid was added to the vessel, and the vessel was capped. The vessel was heated in a microwave at ˜15% power for about 5 minutes, then at ˜30% power for about 10 minutes, and finally at ˜60% power for about 5 minutes. The vessel was then air-cooled. Saturated boric acid solution was added and the solution diluted to volume with distilled deionized water. The resulting sample solution was then analyzed by IRIS™ ICP-AES.

“Seeded prep” indicated that seed crystals of MCM-68 from a prior synthesis of the material were used in the synthesis of the sample used in the present experiments.

“SDA” was used to refer to the (organic) structure directing agent used in the synthesis of the porous crystalline material. The various SDAs (A, B, and C) are shown as structures below Table 1.

Example 16 Micropore Volumes of MCM-68 Examples

The overall surface area of the porous crystalline material was determined by the BET method, as described by S. Brunauer, P. H. Emmett, and E. Teller, J. Am. Chem. Soc., 1938, 60, 309 (hereby incorporated by reference) using nitrogen adsorption-desorption at roughly liquid nitrogen temperatures. The total BET and the t-Plot micropore volumes were measured by liquid nitrogen adsorption/desorption with a Micromeritics Tristar™ II 3020 instrument after degassing of calcined powders of the porous crystalline material for about 4 hours at ˜350° C. More information regarding the method can be found, for example, in “Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density”, S. Lowell et al., Springer, 2004, hereby incorporated by reference for such disclosure.

The micropore volumes and BET areas of the MCM-68 Examples are shown in Table 2.

TABLE 2 Micropore volumes of MCM-68 examples. Micropore Total volume Loss of Steam BET Loss of from N2 micropore Example treatment (m2/g) BET (cm3/g) volume 1 None ~559 — ~0.205 — 2 ~800 C., ~5 hrs ~513  ~8% ~0.186  ~9% 3 ~800 C., ~40 hrs ~445 ~20% ~0.160 ~23% 4 ~538 C., ~3 hrs ~552  ~1% ~0.185 ~10% 6 ~800 C., ~40 hrs ~501 ~10% ~0.178 ~13% 8 None ~502 — ~0.178 — 11 None ~547 — ~0.176 — 12 ~815 C., ~4 hrs ~421 ~23% ~0.142 ~19%

The data in Table 2 appear to show, inter alia:

    • 1) the MCM-68 of Example 2 exhibited good steam stability at ˜800° C. with only ˜9% loss of micropore volume after ˜4 hours and ˜23% loss after ˜40 hours;
    • 2) the MCM-68 of Example 4 appeared to exhibit better steam stability than that of Example 3, with only ˜10% loss of micropore volume after ˜40 hours of steaming;
    • 3) the MCM-68 of Example 3 exhibited a lower micropore volume than Example 1 (unsteamed), presumably due to a phase impurity; and
    • 4) the MCM-68 of Example 12 appeared to exhibit worse steam stability than the MCM-68 of Examples 2 or 4, with ˜19% loss of micropore volume after ˜4 hours of steaming at ˜815° C. The MCM-68 of Example 12 was made by a similar MCM-68 method to that described in Microporous Mesoporous Materials vol. 96, pg. 210. The MCM-68 reported therein was reported to exhibit even lower steam stability, losing ˜70-80% of its micropore volume after steaming at ˜800° C. for ˜5 hours.

Hydrocarbon Sorption Example 17

A test was conducted to determine the utility of the porous crystalline materials prepared according to these Examples for hydrocarbon sorbing.

Porous crystalline materials were pressed to ˜40-60 mesh, and about 1.0 gram of each porous crystalline material was loaded in a separate ˜7-mm ID stainless steel reactor. Porous crystalline materials were each heated to ˜550° C. in a flow of ˜3% O2/N2 for ˜2 hours and cooled to ˜105° C. for testing. A flow of ˜15% H2O, ˜15% CO2, and ˜70% N2 was established at ˜105° C., ˜6 psig, and ˜0.25 std. L/min by a pump and mass flow controllers. H2O was boiled in a capillary tube vaporizer, and process lines were heated for steady flow. The flow was switched to a bypass line, and the hydrocarbon feed was introduced by an Isco™ pump at ˜0.36 mL/hr. The hydrocarbon feed comprised ˜11 wt % ethanol, ˜41 wt % 3-methyl-pentane, ˜14 wt % n-hexane, ˜10 wt % 2,2,4-trimethylpentane (iso-octane), and ˜24 wt % toluene. The flow of CO2, H2O, hydrocarbon, and N2 was then switched from bypass to the porous crystalline material while maintaining ˜6.0 psig pressure using a back-pressure regulator. A gas chromatograph (GC) with a DB-1™ column and FID detected hydrocarbons. The GC method separated ethanol, hexanes, iso-octane, and toluene in ˜2.5 minutes. 3-Methylpentane and n-hexane were observed to have approximately the same retention time.

The results of the hydrocarbon sorbing test are summarized in Table 3. Table 3 provides data useful for obtaining the hydrocarbon selectivity for the porous crystalline materials of the various examples for the particular hydrocarbons used in the hydrocarbon sorbing tests.

TABLE 3 Hydrocarbon sorption by MCM-68 samples. Net Uptake (g species/100 g zeolite Duration of 95-100% uptake (s) Example Net Ethanol Hexane Isooctane Toluene Ethanol Hexane Isooctane Toluene  2 9.4 <0.1 2.5 4.0 2.9 100 1100 4900 1500  3 6.8 0.1 2.0 2.5 2.2 200 800 3200 1100  4 7.4 1.0 2.1 2.1 2.1 500 800 2200 1100  5 8.1 0.6 2.1 2.9 2.4 200 900 3500 1200  6 9.1 0.1 2.4 3.7 2.9 100 1100 4700 1500  7 8.8 0.1 2.3 3.7 2.8 100 1000 4000 1300  8 5.0 1.1 1.2 1.3 1.5 1300 500 1600 900  9 6.0 0.3 1.5 2.4 1.8 800 800 3100 1200 10 7.1 0.3 2.7 1.8* 2.4 300 900 2800* 1300 14 7.3 0.7 3.3 0.6 2.6 1000 900 900 1500 ZSM-5 4.9 0.7 3.1 0.1 1.0 400 400 0 400 (comparative) Ce/USY 4.6 0.5 1.1 1.5 1.6 500 300 1000 700 (comparative) *Run stopped voluntarily at ~2800 seconds

“Net uptake” in Table 3 represents the specific sorption of the indicated hydrocarbon (including ethanol) by the porous crystalline material, that is, the amount of the indicated hydrocarbon or ethanol sorbed by the porous crystalline material up to saturation, as weight of hydrocarbon per weight of porous crystalline material. This value was obtained by integrating the percentage of the particular hydrocarbon (including ethanol) in the flow over the test bed sorbed by the porous crystalline material versus time, up to saturation. “Total” Net Uptake in Table 3 represents the sum of the net uptakes of the individual hydrocarbons (including ethanol).

“Duration of 95-100% uptake” in Table 3 represents the duration of time (in seconds) that the porous crystalline material sorbs at least 95% of each indicated substance from the feed stream, indicated by breakthrough of the substance into the flow over the porous crystalline material during the sorption step of the experiment.

Claims

1. A method of treating a cold-start engine exhaust gas stream comprising hydrocarbons and/or other pollutants, the method comprising:

a) flowing the exhaust gas stream over a bed of a porous crystalline material, the porous crystalline material containing both 10- and 12-membered ring pore channels to provide a first treated exhaust stream having lower total hydrocarbon content than that of the exhaust gas stream, wherein the porous crystalline material exhibits one or more of the following properties: (i) a decrease in micropore volume no more than about 15% after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least 1.3 wt %; (iii) a monovalent metal cation content of 1.0 wt % or less of the porous crystalline material; (iv) a content of ammonium ions (NH4+) of at least 0.5 wt %; and (v) a content of multivalent metal ions of at least 0.5 wt %.

2. The method of claim 1, wherein the first treated exhaust gas stream comprises substantially no hydrocarbons up to a hydrocarbons content of 1 wt % of the exhaust gas stream.

3. The method of claim 1, further comprising:

b) flowing the first treated exhaust gas stream over a catalyst to convert any residual hydrocarbons and other pollutants contained in the first treated exhaust gas stream to conversion products to provide a second treated exhaust stream; and
c) discharging the second treated exhaust stream.

4. The method of claim 1, wherein the porous crystalline material comprises 0.2 wt % or less of monovalent metal cations.

5. The method of claim 1, wherein the porous crystalline material comprises substantially no potassium cations.

6. The method of claim 1, wherein the porous crystalline material has a silicon to aluminum ratio from 10 to 25.

7. The method of claim 1, wherein an IZA framework type of the porous crystalline material comprises one or more of BOG, CON, DFO, ITN, IVR, IWW, MSE, SFV, UOV, USI, and mixtures and intergrowths thereof.

8. The method of claim 1, wherein the porous crystalline material has an MSE framework type.

9. The method of claim 1, wherein the porous crystalline material contains a metal deposited thereon comprising platinum, palladium, rhodium, ruthenium, or a mixture thereof.

10. The method of claim 9, wherein the metal comprises a mixture of platinum and palladium.

11. The method of claim 1, wherein the porous crystalline material is synthesized using a structure directing agent comprising N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dications; N,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2,3:5,6-dipyrrolidinium dications; 1,1-dialkyl-4-cyclohexyl-piperazin-1-ium cations; 1,1-dialkyl-4-alkylcyclohexylpiperazin-1-ium cations; 3-hydroxy-1-(4-(1-methylpiperidin-1-ium-1-yl)butyl)quinuclidin-1-ium cations, 3-hydroxy-1-(5-(1-methylpiperidin-1-ium-1-yl)pentyl)quinuclidin-1-ium cations, 1,1′-(butane-1,4-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-(pentane-1,5-diyl)bis(1-methyl-piperidin-1-ium) cations, 1,1′-(hexane-1,6-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidin-1-ium)tetraethyl-ammonium cations, a cation satisfying one or more of the following formulae, or a combination thereof: where A is a >CR13R14 group, a >C═O group, or an >O group, where R1, R2, R3, R4, R7, R8, R9, and R10 are each independently hydrogen, a hydroxyl group, or a C1-C5 hydrocarbon chain, where R13 and R14 are each independently hydrogen, a C1-C5 hydrocarbon chain, a piperidinyl group or a pyrrolidinyl group, where R5, R6, R11, and R12 are each independently a C1-C5 hydrocarbon chain.

12. The method of claim 1, wherein the porous crystalline material bed contains at least one further porous crystalline material having 10-membered ring pore channels or 12-membered ring pore channels, but not both 10-membered ring and 12-membered ring pore channels.

13. The method of claim 12, wherein the at least one further porous crystalline material has a framework type comprising BEA, FAU, MFI, FER, or a combination or intergrowth thereof.

14. The method of claim 1, wherein the porous crystalline material comprises MCM-68 having a Si/Al2 mole ratio greater than 8.

15. A method of treating a cold-start engine exhaust gas stream comprising hydrocarbons and/or other pollutants, the method comprising:

a) flowing the exhaust gas stream over a bed of a porous crystalline material, the porous crystalline material containing an 11-membered ring pore channel to provide a first treated exhaust stream having lower total hydrocarbon content than that of the exhaust gas stream, wherein the porous crystalline material exhibits one or more of the following properties: (i) a decrease in micropore volume no more than about 15% after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours; (ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least 1.3 wt %; (iii) a monovalent metal cation content of 1.0 wt % or less of the porous crystalline material; (iv) a content of ammonium ions (NH4+) of at least 0.5 wt %; and (v) a content of multivalent metal ions of at least 0.5 wt %.

16. The method of claim 15, wherein the porous crystalline material comprises EMM-17, NU-86, or a mixture or intergrowth thereof.

17. A hydrocarbon sorption apparatus comprising a porous crystalline material bed, the porous crystalline material bed comprising a porous crystalline material (1) containing both 10- and 12-membered ring pore channels or (2) containing an 11-membered ring pore channel, wherein the porous crystalline material exhibits one or more of the following properties:

(i) a decrease in micropore volume no more than about 15% after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours;
(ii) a surface hydroxyl group content after exposure to 100% steam at 800° C. and atmospheric pressure for 5 hours that is less than one or more of (a) a surface hydroxyl group content of an otherwise identical but unsteamed porous crystalline material, (b) a surface hydroxyl group content of an otherwise identical porous crystalline material after exposure to 100% steam at a temperature of 550° C. and atmospheric pressure for 5 hours, and (c) a surface hydroxyl group content of an unsteamed porous crystalline material having a monovalent metal cation content of at least 1.3 wt %;
(iii) a monovalent metal cation content of 1.0 wt % or less of the porous crystalline material;
(iv) a content of ammonium ions (NH4+) of at least 0.5 wt %; and
(v) a content of multivalent metal ions of at least 0.5 wt %.

18. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material comprises 0.2 wt % or less of monovalent metal cations.

19. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material comprises substantially no potassium cations.

20. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material has a silicon to aluminum ratio from 10 to 25.

21. The hydrocarbon sorption apparatus of claim 17, wherein an IZA framework type of the porous crystalline material comprises one or more of BOG, CON, DFO, ITN, IVR, IWW, MSE, SFV, UOV, USI, and mixtures and intergrowths thereof.

22. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material comprises EMM-17, NU-86, or a mixture or intergrowth thereof.

23. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material comprises MCM-68.

24. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material contains a metal deposited thereon comprising platinum, palladium, rhodium, ruthenium, or a mixture thereof.

25. The hydrocarbon sorption apparatus of claim 24, wherein the metal comprises a mixture of platinum and palladium.

26. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material is synthesized using a structure directing agent comprising N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dications; N,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2,3:5,6-dipyrrolidinium dications; 1,1-dialkyl-4-cyclohexyl-piperazin-1-ium cations; 1,1-dialkyl-4-alkylcyclohexylpiperazin-1-ium cations; 3-hydroxy-1-(4-(1-methylpiperidin-1-ium-1-yl)butyl)quinuclidin-1-ium cations, 3-hydroxy-1-(5-(1-methylpiperidin-1-ium-1-yl)pentyl)quinuclidin-1-ium cations, 1,1′-(butane-1,4-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-(pentane-1,5-diyl)bis(1-methyl-piperidin-1-ium) cations, 1,1′-(hexane-1,6-diyl)bis(1-methylpiperidin-1-ium) cations, 1,1′-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidin-1-ium)tetraethyl-ammonium cations, a cation satisfying one or more of the following formulae, or a combination thereof: where A is a >CR13R14 group, a >C═O group, or an >O group, where R1, R2, R3, R4, R7, R8, R9, and R10 are each independently hydrogen, a hydroxyl group, or a C1-C5 hydrocarbon chain, where R13 and R14 are each independently hydrogen, a C1-C5 hydrocarbon chain, a piperidinyl group or a pyrrolidinyl group, where R5, R6, R11, and R12 are each independently a C1-C5 hydrocarbon chain.

27. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material bed contains at least one further porous crystalline material having 10-membered ring pore channels or 12-membered ring pore channels, but not both of 10-membered ring and 12-membered ring pore channels.

28. The hydrocarbon sorption apparatus of claim 27, wherein the at least one further porous crystalline material has a framework type comprising BEA, FAU, MFI, FER, or a combination or intergrowth thereof.

29. The hydrocarbon sorption apparatus of claim 17, wherein the porous crystalline material comprises MCM-68 having a Si/Al2 mole ratio greater than 10.

30. The hydrocarbon sorption apparatus of claim 17, further comprising a catalytic converter.

31. The hydrocarbon sorption apparatus of claim 17, wherein the bed of porous crystalline material is in fluid connection with a pipe carrying exhaust gas from an engine and comprising hydrocarbons, and wherein the bed of porous crystalline material is adapted to receive said exhaust gas from said pipe, to allow the exhaust gas to contact the bed of porous crystalline material, and to allow the contacted exhaust gas to flow out of the bed of porous crystalline material.

32. The hydrocarbon sorption apparatus of claim 17, wherein the bed of porous crystalline material is in fluid connection with one or more beds comprising a three-way catalyst and/or a catalyst for oxidizing hydrocarbons and nitrogen-containing compounds present in an exhaust gas.

Patent History
Publication number: 20160102590
Type: Application
Filed: Sep 25, 2015
Publication Date: Apr 14, 2016
Applicant: EXXONMOBIL RESEARCH AND ENGINEERING COMPANY (Annandale, NJ)
Inventors: Brian M. Weiss (Bridgewater, NJ), Scott J. Weigel (Allentown, PA), Karl G. Strohmaier (Port Murray, NJ), William W. Lonergan (Humble, TX)
Application Number: 14/865,006
Classifications
International Classification: F01N 3/08 (20060101); B01D 53/75 (20060101); B01D 53/86 (20060101); B01D 53/04 (20060101);