Abstract: In a process for isomerizing a feed comprising ethylbenzene and a mixture of xylene isomers, the feed is first contacted under xylene isomerization conditions with a first catalyst composition to produce an intermediate product having a higher para-xylene concentration than the feed, and then the intermediate product is contacted under ethylbenzene isomerization conditions with a second catalyst composition. The second catalyst composition comprises a hydrogenation-dehydrogenation component and a molecular sieve having 10-membered ring pores and is effective to selectively isomerize at least part of the ethylbenzene in the intermediate product to para-xylene and thereby produce a further product having a para-xylene concentration greater than the equilibrium concentration of para-xylene at said ethylbenzene isomerization conditions.

Abstract: A process and system is disclosed for removing sulfur from tail-gas emitted from a Claus sulfur recovery process. First, the tail-gas is oxidized so as to convert sulfur therein to sulfur oxides. Oxidized tail-gas is directed into an absorber where a solid absorbent absorbs substantially all the sulfur oxides thereon. After allowing sufficient time for a desired amount of sulfur oxides to be absorbed, absorption is ceased. Next, the solid absorbent containing the absorbed sulfur oxides is contacted with a reducing gas so as to release an off gas containing hydrogen sulfide and sulfur dioxide. Upon releasing sulfur from the solid absorbent, the solid absorbent is regenerated and redirected into the absorber. Sulfur in the off gas emitted by regeneration is concentrated to an extent sufficient for use within a Claus sulfur recovery process for conversion to elemental sulfur.

Abstract: There is provided a substantially binder-free catalytic molecular sieve which has been modified by being ex situ selectivated with a silicon compound. The ex situ selectivation involves exposing the molecular sieve to at least two silicon impregnation sequences, each sequence comprising an impregnation with a silicon compound followed by calcination. The catalyst may be used in a hydrocarbon conversion process, such as toluene disproportionation.

Abstract: There is provided a substantially binder-free catalytic molecular sieve which has been modified by being ex situ selectivated with a silicon compound. The ex situ selectivation involves exposing the molecular sieve to at least two silicon impregnation sequences, each sequence comprising an impregnation with a silicon compound followed by calcination. The catalyst may be used in a hydrocarbon conversion process, such as toluene disproportionation.

Abstract: The present invention provides a process for regenerating a spent aromatics alkylation or transalkylation catalyst comprising a molecular sieve by contacting the spent catalyst with an oxygen-containing gas at a temperature of about 120 to about 600° C. and then contacting the catalyst with an aqueous medium, such as an ammonium nitrate solution, an ammonium carbonate solution or an acid solution.

Abstract: This is a process for upgrading a petroleum naphtha fraction. The naphtha is subjected to reforming and the reformate is cascaded to a benzene and toluene synthesis zone over a benzene and toluene synthesis catalyst comprising a molecular sieve of low acid activity. The preferred molecular sieve is steamed ZSM-5. The benzene and toluene synthesis zone is operated under conditions compatible with the conditions of the reformer such as temperatures of above about 800° F. (427° C.). In one aspect on the invention, the benzene and toluene synthesis catalyst includes a metal hydrogenation component from group VII(B), specifically rhenium. In one mode of operation, the benzene and toluene synthesis catalyst replaces at least a portion of the catalyst in the reformer. The process produces a product containing an increased proportion of benzene, toluene, and/or xylenes, and a reduced portion of alkylated aromatics, as compared to reformate.

Abstract: A synthetic porous crystalline material has the structure of ZSM-5 and a composition involving the molar relationship: X2O3:(n)YO2, wherein X is a trivalent element; Y is a tetravalent element; and n is less than 25, and wherein the slope of the nitrogen sorption isotherm of the material at a partial pressure of nitrogen of 0.4 to 0.7 and a temperature 77° K is greater than 30. The material has a mesoporous surface area (MSA) greater than 45 m2/g and is useful as a catalyst in the liquid phase isomerization of xylene.

Abstract: The patent application discloses an integrated process for reformate upgrading. Such a process enables production of a high value product slate, by incorporating the step of reforming along with reaction/diffusion with a zeolite.

Abstract: A synthetic porous crystalline material has the structure of ZSM-5 and a composition involving the molar relationship:

Abstract: The patent application discloses an integrated process for reformate upgrading. Such a process enables production of a high value product slate, by incorporating the step of reforming along with reaction/diffusion with a zeolite.

Abstract: There is provided a process for producing high-purity meta-xylene by converting a hydrocarbon feedstream comprising at least about 5 wt % ethylbenzene and at least about 20 wt % meta-xylene, over a single molecular sieve catalyst under ethylbenzene conversion conditions sufficient to provide a primary product stream depleted of more than 50% of the ethylbenzene present in the feedstream. The process can further comprise stripping benzene and/or toluene by-products from the primary product stream to provide a secondary product stream comprising at least about 75 wt % mixed ortho-xylene and meta-xylene; and splitting the secondary product stream by removing substantially all of the ortho-xylene present therein to provide a tertiary product stream comprising at least about 95 wt % meta-xylene.

Abstract: A synthetic porous crystalline material has the structure of ZSM-5 and a composition involving the molar relationship: X2O3:(n)YO2, wherein X is a trivalent element; Y is a tetravalent element; and n is less than 25, and wherein the slope of the nitrogen sorption isotherm of the material at a partial pressure of nitrogen of 0.4 to 0.7 and a temperature 77° K is greater than 30. The material has a mesoporous surface area (MSA) greater than 45 m2/g and is useful as a catalyst in the liquid phase isomerization of xylene.

Abstract: A process for producing terephthalic acid and/or dimethyl terephthalate includes contacting a toluene-containing reaction stream with a first catalyst under toluene disproportionation conditions to produce an intermediate product stream of para-xylene with negligible ortho-xylene. The first catalyst includes a crystalline molecular sieve which has an ortho-xylene diffusion rate of at least 50 minutes. The first catalyst can be modified by selectivation with a silicon compound or carbon compound. The intermediate product stream, without need for para-xylene purification, is oxidized to terephthalic acid or dimethyl terephthalate.

Abstract: There is provided an isomerization process using a catalyst comprising a hydrogenation/dehydrogenation component, such as a noble metal, and an acidic solid component comprising a Group IVB metal oxide modified with an oxyanion of a Group VIB metal. An example of this catalyst is zirconia, modified with tungstate and platinum. This catalyst is used to isomerize, for example, C.sub.4 to C.sub.8 paraffins. The feed to this paraffin isomerization reaction may, optionally, include cyclic hydrocarbons, such as benzene or cyclohexane, which may undergo ring opening reactions during the course of the isomerization reaction.

Abstract: This invention relates to a new synthetic porous crystalline material, designated MCM-68, a method and novel polycyclic organic cation for its preparation and its use in catalytic conversion of organic compounds. The new crystalline material exhibits a distinctive X-ray diffraction pattern and has a unique crystal structure which contains at least one channel system, in which each channel is defined by a 12-membered ring of tetrahedrally coordinated atoms, and at least two further, independent channel systems, in each of which each channel is defined by a 10-membered ring of tetrahedrally coordinated atoms, wherein the number of unique 10-membered ring channels is twice the number of 12-membered ring channels.

Abstract: This invention describes a process for the scrubbing of sulfur oxides from the effluent of conventional wet lime/limestone SOx reduction processes in coal or oil-fired plants. The sulfur oxides are oxidatively sorbed onto solid sorbents such as magnesium aluminate spinel. Reduction with the appropriate reducing gases (such as hydrogen) regenerates the catalyst, also yielding a process stream concentrated in SOx. This concentrated SOx stream can then be refed to the front end of the coal or oil-fired plants, with the SOx thus produced ultimately being removed in the conventional wet scrubbing technology.

Abstract: A method for minimizing the loss of xylenes in an ethylbenzene conversion/isomerization process by adding toluene to the feedstock. The concentration of toluene in the feedstock is increased by co-feeding toluene or by recycling toluene separated from the ethylbenzene conversion reactor effluent. The increased toluene concentration reduces the loss of xylenes during the ethylbenzene conversion reaction and under preferred operating conditions increases the amount of xylenes in the product.

Abstract: There is provided a process for shape selective xylene disproportionation that involves contacting a feedstream which includes xylene under conversion conditions, with a molecular sieve catalyst that has been surface modified. The xylene disproportionation process has a selectivity for pseudocumene of over 85%.

Abstract: A method for increasing the efficiency of xylene isomerization by using a two stage isomerization process. In the first stage of the process, a C.sub.9.sup.+ aromatics feedstock is subjected to ethylbenzene conversion and xylene isomerization. Non-C.sub.8 aromatics are removed from the effluent, which is then processed in a second stage of the process to remove para-xylene and isomerize the para-xylene depleted effluent. The effluent from the second stage isomerization unit is then recycled into the inlet of the second stage of the process and a slip stream from the para-xylene separator is recycled to the feedstock and to the effluent of the ethylbenzene conversion unit. In this way, the production of para-xylene is maximized. In a preferred embodiment, toluene is co-fed into the feedstock to minimize the loss of xylenes during the ethylbenzene conversion reaction.

Abstract: There is provided a method for preparing an acidic solid comprising a Group IVB metal oxide modified with an oxyanion of a Group VIB metal. An example of this acidic solid is zirconia, modified with tungstate. This modified solid oxide may be used as a catalyst, for example, to isomerize C.sub.4 to C.sub.8 paraffins. The modified solid oxide is treated with hydrogen at elevated temperatures to enhance catalytic properties of the material.