PROCESS FOR CATALYTIC CRACKING OF A BIOMASS
A process for converting a biomass comprising contacting the biomass with a catalytic cracking catalyst at a temperature of more than 400° C. in a catalytic cracking reactor to produce a product stream containing one or more cracked products and supplying a biomass to the reactor via a feed nozzle having a feed nozzle outlet located between a first section and a second section of the reactor and downstream of an opening of a catalyst supply pipe connected to the first section, wherein the second section comprises a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction.
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This application claims the benefit of Chinese Patent Application No. 201210414204.0, filed on Oct. 25, 2012, the disclosure of which is incorporated herein by reference in its entirety.
TECHNICAL FIELDThe present disclosure relates to a process for catalytic cracking of a biomass. More particularly, the present disclosure relates to a process for catalytic cracking of a pyrolysis oil. Most specifically, the present disclosure relates to a process for catalytic cracking of a pyrolysis oil derived from a material comprising biomass.
BACKGROUNDThis section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present invention. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of any prior art.
With the diminishing supply of petroleum crude oil, use of renewable energy sources is becoming increasingly important for the production of liquid fuels. These fuels from renewable energy sources are often referred to as biofuels.
Biofuels derived from non-edible renewable energy sources, such as cellulosic materials derived from plants, are preferred as these do not compete with food production. These biofuels are also referred to as second generation, renewable or advanced, biofuels.
One of the existing processes comprises pyrolysing such cellulosic materials derived from plants to obtain a pyrolysis oil, and upgrading and subsequently catalytic cracking of the pyrolysis oil to obtain chemicals and fuel products.
In the article titled “Biomass pyrolysis in a circulating fluid bed reactor for production of fuels and chemicals” by A. A. Lappas et al, published in Fuel, vol. 81 (2002), pages 2087-2095, an approach for biomass flash pyrolysis in a circulating fluid bed (CFB) reactor is described. The CFB reactor comprised a vertical riser type reactor (7.08 mm ID). The riser height was 165 cm. An integrated screw feeder system was designed and constructed for effective biomass introduction into the unit. From the screw feeder the biomass was introduced at the bottom of the riser, using a specifically designed injection-mixing system. This system consisted of a large diameter bottom vessel connected through a conical section with the riser reactor. A disadvantage of the process as described by Lappas et al. is that the specific injection-mixing system comprising the integrated screw feeder may be difficult to scale up to a commercial scale. In addition, it may be difficult to retrofit existing FCC units with the injection-mixing system as described.
EP2325281 describes a process for catalytic cracking of a pyrolysis oil derived from material comprising lignocellulose, comprising the steps of a) subjecting a feed comprising the pyrolysis oil to a hydrodeoxygenation step to obtain a product stream comprising a partially deoxygenated pyrolysis oil; b) separating the partially deoxygenated pyrolysis oil having an oxygen content of from 5 to 30 wt % from the product stream obtained in a); c) contacting the partially deoxygenated pyrolysis oil obtained in b) in the presence of a hydrocarbon feed derived from a mineral crude oil with a cracking catalyst under catalytic cracking conditions to obtain a deoxygenated and cracked product stream; and d) separating at least one product fraction from the product stream obtained in c). EP2325281 further describes that the co-feeding in step c) may be attained by blending the partially deoxygenated pyrolysis oil and the hydrocarbon feed streams prior to the entry into a cracking unit, or alternately, by adding them at different stages.
However, in order to scale up the process of EP2325281 to a commercial scale, the process may require improvements to meet nowadays conversion, robustness, maintenance and/or safety requirements.
It would be an advancement in the art to provide a process allowing one to scale up a process for co-feeding of a partially or wholly deoxygenated pyrolysis oil and a hydrocarbon co-feed in a catalytic cracking unit to a commercial scale; and/or to provide a process allowing one to revamp existing commercial catalytic cracking units to allow for co-feeding of a partially or wholly deoxygenated pyrolysis oil and a hydrocarbon co-feed.
SUMMARYRecently, it was found that when feeding a biomass, such as for example a partially or wholly deoxygenated pyrolysis oil in a fluid catalytic cracking unit, coke may form in the fluid catalytic cracking reactor. The formation of this coke in turn may lead to an unstable plug flow in the fluid catalytic cracking reactor. As a consequence the robustness of the fluid catalytic cracking unit decreases and more maintenance may be required.
It has now been found that such coking can be reduced or even avoided by using a specific positioning of a feed nozzle feeding the biomass into the fluid catalytic cracking unit.
In one embodiment, the present disclosure provides a process for converting a biomass, comprising contacting the biomass with a catalytic cracking catalyst at a temperature of more than 400° C. in a catalytic cracking reactor to produce a product stream containing one or more cracked products, wherein the catalytic cracking reactor comprises: a first section; a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction; a third section having a fluid connection to and located downstream of the second section; a catalyst supply pipe being connected to the first section for supplying the catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and a feed nozzle having a feed nozzle outlet for supplying the biomass to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
It has been surprisingly found that if the feed nozzle is located higher, such as at a position above the fluid connection between the first section and the second section, more coke may be formed. It has further been surprisingly found that if the feed nozzle is located lower, such as at a position below the second level of the catalyst supply pipe, also more coke may be formed.
In another embodiment, the present disclosure provides a catalytic cracking reactor comprising—a first section; a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction; a third section having a fluid connection to and located downstream of the second section; a catalyst supply pipe being connected to the first section for supplying a fluid catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and a feed nozzle having a feed nozzle outlet for supplying a feed to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
Other advantages and features of embodiments of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Certain exemplary embodiments are illustrated by the following non-limiting figures.
The present disclosure relates to the catalytic cracking of biomass, and preferably to the catalytic cracking of a pyrolysis oil derived from material comprising biomass. In one embodiment, the present disclosure provides a process for converting a biomass, comprising contacting the biomass with a catalytic cracking catalyst at a temperature of more than 400° C. in a catalytic cracking reactor to produce a product stream containing one or more cracked products, wherein the catalytic cracking reactor comprises: a first section; a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction; a third section having a fluid connection to and located downstream of the second section; a catalyst supply pipe being connected to the first section for supplying the catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and a feed nozzle having a feed nozzle outlet for supplying the biomass to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
By biomass is herein understood a composition of matter of biological origin as opposed to a composition of matter obtained or derived from petroleum, natural gas or coal. Without wishing to be bound by any kind of theory it is believed that such biomass may contain carbon-14 isotope in an abundance of about 0.0000000001%, based on total moles of carbon. Examples of biomass include aquatic plants and algae, agricultural waste and/or forestry waste and/or paper waste and/or plant material obtained from domestic waste. Other examples of biomass can include animal fat, tallow oil and used cooking oil.
Preferably the biomass is a solid biomass material. More preferably the biomass is a material containing cellulose and/or lignocellulose. such a material containing “cellulose” respectively “lignocellulose” is herein also referred to as a “cellulosic”, respectively “lignocellulosic” material. By a cellulosic material is herein understood a material containing cellulose and optionally also lignin and/or hemicellulose. By a lignocellulosic material is herein understood a material containing cellulose and lignin and optionally hemicellulose.
In a preferred embodiment, the biomass may also be a pyrolysis oil derived from a material containing biomass, more preferably a pyrolysis oil derived from a material containing cellulose and/or lignocellulose. Preferably the pyrolysis oil is derived from a cellulosic or lignocellulosic material such as for example agricultural wastes such as corn stover, soybean stover, corn cobs, rice straw, rice hulls, oat hulls, corn fibre, cereal straws such as wheat, barley, rye and oat straw; grasses; forestry products and/or forestry residues such as wood and wood-related materials such as sawdust; waste paper; sugar processing residues such as bagasse and beet pulp; or mixtures thereof. More preferably the pyrolysis oil is derived from a cellulosic or lignocellulosic material selected from the group consisting of wood, sawdust, straw, grass, bagasse, corn stover and/or mixtures thereof.
In one embodiment, the cellulosic or lignocellulosic material may have undergone drying, demineralization, torrefaction, steam explosion, particle size reduction, densification and/or pelletization before being used as biomass in the process according to the invention or before being pyrolysed, to allow for improved process operability and economics.
If the biomass in the process according to the invention comprises a pyrolysis oil as described above, such pyrolysis oil can suitably be produced by pyrolysing the material comprising the biomass. In a preferred embodiment the process according to the invention therefore further comprises a step of preparing a pyrolysis oil as described above, which step comprises pyrolysing a material comprising a biomass to produce a pyrolysis product.
By pyrolysis or pyrolysing is herein understood the decomposition of the material comprising the biomass, in the presence or in the essential absence of a catalyst, at a temperature of equal to or more than 380° C.
In one embodiment, the concentration of oxygen is preferably less than the concentration required for complete combustion. Preferably pyrolysis is carried out in an oxygen-poor, preferably an oxygen-free, atmosphere. By an oxygen-poor atmosphere is understood an atmosphere containing equal to or less than 15 vol.% oxygen, preferably equal to or less than 10 vol.% oxygen and more preferably equal to or less than 5 vol.% oxygen. By an oxygen-free atmosphere is understood an atmosphere where oxygen is essentially absent. More preferably pyrolysis is carried out in an atmosphere containing equal to or less than 5 vol.% oxygen, more preferably equal to or less than 1 vol.% oxygen and most preferably equal to or less than 0.1 vol.% oxygen. In a most preferred embodiment pyrolysis is carried out in the essential absence of oxygen.
The material comprising the biomass is preferably pyrolysed at a pyrolysis temperature of equal to or more than 400° C., more preferably equal to or more than 450° C., even more preferably equal to or more than 500° C. and most preferably equal to or more than 550° C. The pyrolysis temperature is further preferably equal to or less than 800° C., more preferably equal to or less than 700° C. and most preferably equal to or less than 650° C.
The pyrolysis pressure may vary widely. For practical purposes a pressure in the range from 0.01 to 0.5 MPa (MegaPascal), more preferably in the range from 0.1 to 0.2 MPa is preferred. Most preferred is an atmospheric pressure (about 0.1 MPa).
In certain methods, chemicals may be employed for a pretreatment of the biomass, or catalysts may be added to the pyrolysis mixture, cf. for example, H Wang cs., “Effect of acid, alkali, and steam explosion pretreatment on characteristics of bio-oil produced from pinewood”, Energy Fuels (2011) 25, p. 3758-3764. Preferably the pyrolysis does not include an externally added catalyst.
In a preferred pyrolysis process, generally referred to as a flash pyrolysis process, the biomass is rapidly heated (for example within 3 seconds) in the essential absence of oxygen to a temperature in the range of from 400° C. to 600° C. and kept at that temperature for a short period of time (for example equal to or less than 3 seconds). Such flash pyrolysis processes are known, for example from A. Oasmaa et al, “Fast pyrolysis of Forestry Residue 1: Effect of extractives on phase separation of pyrolysis liquids,” Energy & Fuels, volume 17, number 1, 2003, pages 1-12; and A. Oasmaa et al, “Fast pyrolysis bio-oils from wood and agricultural residues,” Energy & Fuels, 2010, vol. 24, pages 1380-1388; U.S. Pat. No. 4,876,108; U.S. Pat. No. 5,961,786; and U.S. Pat. No. 5,395,455.
During such pyrolysis of the material comprising the biomass, a pyrolysis product is produced. The pyrolysis product may contain gas, solids (char), one or more oily phase(s), and optionally an aqueous phase. The oily phase(s) will hereafter be referred to as pyrolysis oil. The pyrolysis oil can be separated from the pyrolysis product by any method known by the skilled person to be suitable for that purpose. This includes conventional methods such as filtration, centrifugation, cyclone separation, extraction, membrane separation and/or phase separation.
The pyrolysis oil may include for example carbohydrates, olefins, paraffins, oxygenates and/or optionally some residual water. By an oxygenate is herein understood a compound containing at least one or more carbon atoms, one or more hydrogen atoms and one or more oxygen atoms. The oxygenates may for example include aldehydes, carboxylic acids, alkanols, phenols and ketones.
Preferably, the pyrolysis oil comprises carbon in an amount equal to or more than 25 wt %, more preferably equal to or more than 35 wt % and most preferably equal to or more than 40 wt %, and preferably equal to or less than 70 wt %, more preferably equal to or less than 60 wt %, based on the total weight of the pyrolysis oil.
The pyrolysis oil further preferably comprises hydrogen in an amount equal to or more than 1 wt %, more preferably equal to or more than 5 wt %, and preferably equal to or less than 15 wt %, more preferably equal to or less than 10 wt %, based on the total weight of the pyrolysis oil. (on a dry basis).
The pyrolysis oil further preferably comprises oxygen in an amount equal to or more than 25 wt %, more preferably equal to or more than 35 wt %, and preferably equal to or less than 70 wt %, more preferably equal to or less than 60 wt %, based on the total weight of the pyrolysis oil. Such oxygen content is preferably defined on a dry basis. By a dry basis is understood excluding water.
The pyrolysis oil may also contain nitrogen and/or sulphur. If nitrogen is present, the pyrolysis oil preferably comprises nitrogen in an amount equal to or more than 0.001 wt %, more preferably equal to or more than 0.1 wt %, and preferably equal to or less than 1.5 wt %, more preferably equal to or less than 0.5 wt %, based on the total weight of the pyrolysis oil.
If sulphur is present, the pyrolysis oil preferably comprises sulphur in an amount equal to or more than 0.001 wt %, more preferably equal to or more than 0.01 wt %, and preferably equal to or less than 1 wt %, more preferably equal to or less than 0.1 wt %, based on the total weight of the pyrolysis oil.
If present, the pyrolysis oil preferably comprises water in an amount equal to or more than 0.1 wt %, more preferably equal to or more than 1 wt %, still more preferably equal to or more than 5 wt %, and preferably equal to or less than 55 wt %, more preferably equal to or less than 45 wt %, and still more preferably equal to or less than 35 wt %, still more preferably equal to or less than 30 wt %, most preferably equal to or less than 25 wt %, based on the total weight of the pyrolysis oil.
Preferably, the Total acid number of the pyrolysis oil may be at most 250 mg KOH/g, more preferably in the range of from 5 mg KOH/g to 200 mg KOH/g, for example in the range of from 10 mg KOH/g to 150 mg KOH/g. As used herein, carbon content, hydrogen content and nitrogen content are as measured by ASTM D5291, and sulfur content is as measured by ASTM D2622. Oxygen content is calculated by difference, such that the sum of carbon content, hydrogen content, oxygen content, nitrogen content and sulfur content is 100 wt %. Water content is as measured by ASTM E203. As used herein, Total acid number is as measured by using ASTM D664. The presence of water, oxygen-, nitrogen- and/or sulphur-containing compounds and the high Total acid number (TAN) makes the pyrolysis product less suitable for processing in a catalytic cracking unit.
In a preferred embodiment, the pyrolysis oil may further have been subjected to a hydrodeoxygenation step. In the hydrodeoxygenation step a product may be produced comprising an at least partially deoxygenated pyrolysis oil. This step is further referred to as hydrodeoxygenation (HDO) reaction. By a hydrodeoxygenation is herein preferably understood reducing the concentration of oxygen-containing compounds with the help of hydrogen in the presence of a hydrodeoxygenation catalyst.
In one embodiment, the hydrodeoxygenation step preferably comprises contacting a feed comprising the pyrolysis oil with hydrogen in the presence of an hydrodeoxygenation catalyst at a temperature in the range from equal to or more than 200° C., more preferably equal to or more than 250° C., and most preferably equal to or more than 280° C., to equal to or less than 450° C., more preferably equal to or less than 400° C., and most preferably equal to or less than 350° C. Reference herein to the hydro-deoxygenation temperature is to the maximum temperature that is occurring in a hydro-deoxygenation step. The total pressure during the hydrodeoxygenation step may vary, for example depending on the amount of water that may be present in the feed. Preferably the total pressure during the hydrodeoxygenation step is in the range of from equal to or more than 1.0 MegaPascal, more preferably equal to or more than 5.0 MegaPascal to equal to or less than 35.0 MegaPascal, more preferably equal to or less than 30.0 MegaPascal. Preferably the partial hydrogen pressure during the hydrodeoxygenation step is in the range of equal to or more than 0.2 MegaPascal, more preferably equal to or more than 2.0 MegaPascal to equal to or less than 35.0 MegaPascal, more preferably equal to or less than 30.0 MegaPascal.
The hydrodeoxygenation catalyst can be any type of hydrodeoxygenation catalyst known by the person skilled in the art to be suitable for this purpose. The hydrodeoxygenation catalyst preferably comprises one or more hydrodeoxygenation metal(s), preferably supported on a catalyst support. The one or more hydrodeoxygenation metal(s) are preferably chosen from Group VIII and/or Group VIB of the Periodic Table of Elements. The hydrodeoxygenation metal may for example be present as a mixture, alloy or organometallic compound. Preferably the one or more hydrodeoxygenation metal(s) is/are chosen from the group consisting of Nickel (Ni), Chromium (Cr), Molybdenum (Mo), Tungsten (W), Cobalt (Co), Platinum (Pt), Palladium (Pd), Rhodium (Rh), Ruthenium (Ru), Iridium (Ir), Osmium (Os), Copper (Cu), iron (Fe), Zink (Zn), Gallium (Ga), Indium (In), Vanadium (V) and mixtures thereof. The one or more metal(s) may be present in elementary form; in the form of alloys or mixtures; and/or in the form of oxides, sulfides or other metal-organic compounds. Preferably the hydrodeoxygenation catalyst is a catalyst comprising Tungsten, Ruthenium, Rhenium, Cobalt, Nickel, Copper, Molybdenum, alloys thereof and/or any combination thereof.
If the hydrodeoxygenation catalyst comprises a catalyst support, such catalyst support may be shaped in the form of balls, rings or otherwise shaped extrudates. The catalyst support may comprise a refractory oxide or mixtures thereof, preferably alumina, amorphous silica-alumina, titania, silica, ceria, zirconia; or it may comprise an inert component such as carbon or silicon carbide. The catalyst support may further comprise a zeolitic compound such as for example zeolite Y, zeolite beta, ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48, SAPO-11, SAPO-41, and ferrierite.
In addition to the hydrodeoxygenation step, the pyrolysis oil may have been subjected to further steps, if so desired or necessary. For example, if desired, the pyrolysis oil may further have been subjected to a hydrodesulphurization and/or hydrodenitrogenation of the feed comprising the pyrolysis oil. Hydrodesulphurization may reduce the concentration of any sulphur-containing hydrocarbons. Hydrodenitrogenation may reduce the concentration of any nitrogen-containing hydrocarbons. Such hydrodesulphurization and/or hydrodenitrogenation, may be carried out before, after and/or simultaneously with the hydrodeoxygenation.
After such a hydrodeoxygenation of a pyrolysis oil, a product comprising an at least partially deoxygenated pyrolysis oil may be obtained. This product may contain a gaseous phase, solids, one or more oily phase(s), and optionally an aqueous phase. In this case the gaseous products may be separated from a total liquid product, which total liquid product may preferably be separated into an aqueous phase comprising water soluble compounds, and at least one organic phase comprising the at least partially (hydro-) deoxygenated pyrolysis oil. Any solids may for example be removed by means of filtering.
The pyrolysis oil may have been partially or wholly deoxygenated. The oxygen content (on dry basis) of the one or more organic phases, hereinafter referred to as the at least partially deoxygenated pyrolysis oil, preferably lies in the range from equal to or more than 0.0 wt %, more preferably equal to or more than 0.5 wt %, still more preferably equal to or more than 5 wt % and most preferably equal to or more than 8 wt % to equal to or less than 30 wt %, more preferably equal to or less than 20 wt % and most preferably equal to or less than 15 wt % (on dry basis) of the total weight of the one or more organic phases.
In a preferred embodiment, the biomass comprises an at least partially deoxygenated pyrolysis oil derived from a material comprising biomass. Unless specified otherwise, general references to “pyrolysis oil” herein below are to be understood to refer to both a non-hydrodeoxygenated pyrolysis oil as well as to an at least partially deoxygenated pyrolysis oil.
In a preferred embodiment, the biomass is co-fed to the catalytic cracking reactor with an additional hydrocarbon feed. One or more streams of an additional hydrocarbon feed may be supplied to the catalytic cracking reactor. The one or more streams of additional hydrocarbon feed may be fed to the catalytic cracking reactor as a stream comprising a mixture containing both biomass and the additional hydrocarbon feed; as a stream separate from the biomass; or both. The additional hydrocarbon feed may suitably be supplied to any of the sections of the catalytic cracking reactor, but is preferably supplied to either the first or the third section. If the additional hydrocarbon feed is supplied as part of a mixture containing both biomass and the additional hydrocarbon feed, it is suitably supplied to the first section of the catalytic cracking reactor. If the additional hydrocarbon feed is supplied as one or more separate streams it may conveniently be supplied to the first section, the third section or both.
By a hydrocarbon feed is herein understood a feed that contains one or more hydrocarbon compounds. By a hydrocarbon compound is herein preferably understood a compound that consists of hydrogen and carbon. Examples of hydrocarbon compounds include paraffins (including naphthenes), olefins and aromatics.
The hydrocarbon feed can be any hydrocarbon feed known to the skilled person to be suitable as a feed for a catalytic cracking unit. The hydrocarbon feed can for example be derived from a conventional crude oil (also sometimes referred to as a petroleum oil or mineral oil), an unconventional crude oil (that is, oil produced or extracted using techniques other than the traditional oil well method) or a Fisher Tropsch oil (sometimes also referred to as a synthetic oil) and/or a mixture of any of these.
Preferably, the hydrocarbon feed comprises a hydrocarbon feed that is partly or wholly derived from a petroleum crude oil. More preferably the hydrocarbon feed is an essentially completely petroleum-derived hydrocarbon feed, as opposed to a biomass-derived hydrocarbon feed. Examples of conventional crude oils (also called petroleum oils) include West Texas Intermediate crude oil, Brent crude oil, Dubai-Oman crude oil, Arabian Light crude oil, Midway Sunset crude oil or Tapis crude oil.
More preferably the hydrocarbon feed comprises a fraction of a petroleum crude oil, unconventional crude oil or synthetic crude oil. Preferred fractions include straight run (atmospheric) gas oils, flashed distillate, vacuum gas oils (VGO), coker gas oils, diesel, gasoline, kerosene, naphtha, liquefied petroleum gases, atmospheric residue (“long residue”) and vacuum residue (“short residue”) and/or mixtures thereof. Most preferably the hydrocarbon feed comprises an atmospheric residue, vacuum residue and/or a vacuum gas oil.
In one embodiment, the hydrocarbon feed preferably has a 5 wt % boiling point at a pressure of 0.1 MegaPascal, as measured by means of distillation as based on ASTM D86 titled “Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure”, respectively as measured by ASTM D1160 titled “Standard Test Method for Distillation of Petroleum Products at Reduced Pressure,” of equal to or more than 100° C., more preferably equal to or more than 150° C. An example of such a hydrocarbon feed is a vacuum gas oil.
In another embodiment, the hydrocarbon feed preferably has a 5 wt % boiling point at a pressure of 0.1 MegaPascal, as measured by means of distillation based on ASTM D86 titled “Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure”, respectively as measured by ASTM D1160 titled “Standard Test Method for Distillation of Petroleum Products at Reduced Pressure,” of equal to or more than 200° C., more preferably equal to or more than 220° C., most preferably equal to or more than 240° C. An example of such a hydrocarbon feed is long residue.
In a further preferred embodiment, equal to or more than 70 wt %, preferably equal to or more than 80 wt %, more preferably equal to or more than 90 wt % and still more preferably equal to or more than 95 wt % of the hydrocarbon feed boils in the range from equal to or more than 150° C. to equal to or less than 600° C. at a pressure of 0.1 MegaPascal, as measured by means of a distillation by ASTM D86 titled “Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure,” respectively as measured by ASTM D1160 titled “Standard Test Method for Distillation of Petroleum Products at Reduced Pressure.”
The composition of the hydrocarbon feed may vary widely. Preferably the hydrocarbon feed comprises in the range from equal to or more than 50 wt %, more preferably from equal to or more than 75 wt %, and most preferably from equal to or more than 90 wt % to equal to or less than 100 wt % of compounds consisting only of carbon and hydrogen, based on the total weight of the hydrocarbon feed.
In one preferred embodiment, the hydrocarbon feed comprises equal to or more than 1 wt % paraffins, more preferably equal to or more than 5 wt % paraffins, and most preferably equal to or more than 10 wt % paraffins, and preferably equal to or less than 100 wt % paraffins, more preferably equal to or less than 90 wt % paraffins, and most preferably equal to or less than 30 wt % paraffins, based on the total hydrocarbon feed. By paraffins all of normal-, cyclo- and branched-paraffins are understood. For practical purposes the paraffin content of all hydrocarbon feeds having an initial boiling point of at least 260° C. can be measured by means of ASTM method D2007-03 titled “Standard test method for characteristic groups in rubber extender and processing oils and other petroleum-derived oils by clay-gel absorption chromatographic method,” wherein the amount of saturates will be representative for the paraffin content. For all other hydrocarbon feeds, the paraffin content of the hydrocarbon feed can be measured by means of comprehensive multi-dimensional gas chromatography (GC×GC), as described in P. J. Schoenmakers, J. L. M. M. Oomen, J. Blomberg, W. Genuit, G. van Velzen, J. Chromatogr. A, 892 (2000) p. 29 and further.
In one embodiment, the hydrocarbon feed is preferably heated to a temperature in the range from equal to or more than 50° C. to equal to or less than 140° C. to prepare a preheated hydrocarbon feed. More preferably the hydrocarbon feed is heated to a temperature of equal to or more than 70° C., more preferably a temperature of equal to or more than 90° C. and more preferably the hydrocarbon feed is heated to a temperature of equal to or less than 130° C., more preferably equal to or less than 120° C.
In one embodiment, the preheated hydrocarbon feed is preferably in the liquid state, gaseous state or partially liquid—partially gaseous state. Heating of the hydrocarbon feed can be carried out in any manner known by the person skilled in the art to be suitable therefore. For example, the hydrocarbon feed may be heated in one or more heat exchangers.
In an especially preferred embodiment, an at least partially deoxygenated pyrolysis oil is mixed with an additional hydrocarbon feed as described herein to prepare a feed mixture and the process according to the invention comprises contacting such feed mixture with a catalytic cracking catalyst at a temperature of more than 400° C. in a catalytic cracking reactor to produce a product stream containing one or more cracked products. Preferably such at least partially deoxygenated pyrolysis oil may be mixed with such additional hydrocarbon feed in the feed nozzle as described herein. Alternatively such at least partially deoxygenated pyrolysis oil may be mixed with such additional hydrocarbon feed to prepare a feed mixture before entering the feed nozzle and such feed mixture may be supplied to the catalytic cracking reactor via the feed nozzle as described herein.
Preferably, any biomass and any additional hydrocarbon feed may be combined in a weight ratio of biomass to hydrocarbon feed of at least 0.5/99.5, more preferably at least 1/99, still more preferably at least 2/98, respectively. Preferably, any biomass and any additional hydrocarbon feed may be combined in a weight ratio of biomass to hydrocarbon feed of at most 75/25, more preferably at most 50/50, even more preferably at most 20/80, and most preferably at most 15/85 respectively.
In one embodiment, the amount of any biomass in a feed mixture containing biomass and an additional hydrocarbon feed is preferably equal to or less than 30 wt %, more preferably equal to or less than 20 wt %, most preferably equal to or less than 10 wt % and even more preferably equal to or less than 5 wt %, based on the total weight of feed mixture. For practical purposes the amount of any biomass in a feed mixture containing biomass and an additional hydrocarbon feed is preferably equal to or more than 0.1 wt %, more preferably equal to or more than 1 wt %, based on the total weight of the feed mixture.
Such a feed mixture may suitably be atomized within the feed nozzle to prepare an atomized feed mixture. The atomizing within the feed nozzle may suitably be carried out with the help of a dispersion or atomizing gas. Preferred gases include steam and nitrogen. The atomized feed mixture may suitably be contacted with the catalytic cracking catalyst at a temperature of more than 400° C. in the catalytic cracking reactor to produce a product stream containing one or more cracked products.
The present disclosure also provides a catalytic cracking reactor comprising a first section; a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction; a third section having a fluid connection to and located downstream of the second section; a catalyst supply pipe being connected to the first section for supplying the catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and a feed nozzle having a feed nozzle outlet for supplying the biomass to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
In a preferred embodiment, each of the first section, the second section and third section as described herein are essentially co-axially arranged around the same longitudinal axis. More preferably, the first section and the second section as described herein are essentially tubular shaped around such same longitudinal axis, and the second section as described herein is essentially conically shaped around such same longitudinal axis. Preferably, the axis is an essentially vertically arranged axis. In a preferred embodiment the catalytic cracking reactor is essentially vertically arranged, where the first section is located at the bottom of the reactor, the second section is located on top of the first section and the third section is located on top of the second section. The walls of each of the sections are preferably connected to each other such that essentially one reactor wall is formed.
In on embodiment, the catalytic cracking reactor is preferably a fluid catalytic cracking reactor. By a fluid catalytic cracking reactor is herein understood a reactor suitable for carrying out a fluid catalytic cracking process. In such a fluid catalytic cracking process a fluid catalytic cracking catalyst is used. In a preferred embodiment the process according to the invention is therefore a fluid catalytic cracking process, wherein the catalytic cracking reactor is a fluid catalytic cracking reactor and the catalytic cracking catalyst is a fluid catalytic cracking catalyst.
More preferably, the catalytic cracking reactor is a riser reactor. Such a riser reactor is especially suitable as fluid catalytic cracking reactor in a fluid catalytic cracking process.
In such a riser reactor a fluid catalytic cracking catalyst can conveniently flow from the most upstream end to the most downstream end of the reactor, that is, in this case from the bottom of the riser reactor upwards to the top of the riser reactor. Examples of suitable riser reactors are described in the Handbook titled “Fluid Catalytic Cracking technology and operations”, by Joseph W. Wilson, published by PennWell Publishing Company (1997), chapter 3, especially pages 101 to 112, herein incorporated by reference. For example, the riser reactor may be a so-called internal riser reactor or a so-called external riser reactor as described therein.
In one embodiment, the first section is preferably a first section having an essentially constant inner diameter. The first section preferably has a maximum inner diameter of equal to or more than 0.05 meter, more preferably equal to or more than 0.4 meter, even more preferably equal to or more than 0.8 meter, and most preferably equal to or more than 1 meter, and such maximum inner diameter is preferably equal to or less than 5 meters, more preferably equal to or less than 4 meters, most preferably equal to or less than 2 meters. The height of the first section preferably lies in the range from equal to or more than 0.5 meter to equal to or less than 5 meter. In a fluid catalytic cracking reactor, especially in a riser reactor, this first section is sometimes also referred to as bottom section or liftpot.
In the first section the catalytic cracking catalyst, the biomass and/or optionally any additional hydrocarbon co-feed can be fluidized by a fluidizing medium, which fluidizing medium preferably flows from the first section in a downstream direction to the third section. Suitably this fluidizing medium may be supplied to the first section via one or more feed nozzles. Preferably the fluidizing medium is a gas. In a riser reactor such a fluidizing medium may sometimes also be referred to as a liftgas, which liftgas flows from the bottom section of the riser reactor to the top of the riser reactor. The fluidizing medium for fluidizing the catalytic cracking catalyst may for example be provided by a ring-shaped gas distributor located more upstream of the catalyst supply pipe. For example in a riser reactor the liftgas for lifting the catalytic cracking catalyst may be supplied by such as ring-shaped gas distributor located at the bottom of the liftpot. The fluidizing medium for fluidizing the biomass and/or optionally any additional hydrocarbon co-feed, may conveniently be supplied via one or more bottom entry feed nozzles and/or one or more side entry feed nozzles.
Examples of such a fluidizing medium or liftgas include steam, nitrogen, vaporized oil and/or oil fractions such as for example liquefied petroleum gas, gasoline, diesel, kerosene or naphtha, and mixtures thereof. More preferably, the fluidizing medium contains or consists of steam and/or nitrogen.
In one embodiment, the second section has a fluid connection to and is located downstream of the first section. In a preferred embodiment, the second section has an inner diameter which decreases in a downstream direction. Preferably, the second section essentially has the shape of a so called topped cone. In a riser reactor, the second section may be a connecting area, connecting the so-called liftpot with the so-called riser reactor standpipe. The second section may sometimes also be referred to as “cone section.”
In one embodiment, the third section has a fluid connection to and is located downstream of the second section. In one preferred embodiment the third section has an essentially constant inner diameter and the inner diameter of the third section is smaller than the smallest inner diameter of the first section.
In another preferred embodiment, the third section has an inner diameter which increases in a downstream direction, and the most upstream inner diameter of the third section is smaller than the smallest inner diameter of the first section.
The third section preferably has a maximum inner diameter of equal to or more than 0.01 meter, more preferably equal to or more than 0.3 meter, even more preferably equal to or more than 0.6 meter, still more preferably equal to or more than 1 meter and preferably a maximum inner diameter equal to or less than 3 meter, more preferably equal to or less than 2.5 meter, even more preferably equal to or less than 2 meter and most preferably equal to or less than 1.8 meter. By a maximum inner diameter for a specific section is herein preferably understood the largest inner diameter present within that section. In a riser reactor the third section is sometimes also referred to a as riser reactor standpipe.
In one embodiment, the catalytic cracking reactor further comprises a catalyst supply pipe being connected to the first section for supplying the catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level. More preferably, the catalyst supply pipe is connected to a fluid passage in a side wall of the first section. The catalyst supply pipe can suitably supply a fluid catalytic cracking catalyst to the first section. In a riser reactor this catalyst supply pipe may also be referred to as catalyst standpipe. In such a case the second level may refer to the most upper border of the standpipe outlet and the first level may refer to the most bottom border of the standpipe outlet.
In another embodiment, the catalytic cracking reactor further comprises a feed nozzle having a feed nozzle outlet for supplying the biomass to the reactor and this feed nozzle outlet is located between the second level and the fluid connection between the first section and the second section. In a riser reactor this feed nozzle may therefore have a feed nozzle outlet located between the horizontal plane leveling the most upper border of the standpipe outlet and the plane where the connecting area as describe above starts. The latter may preferably be the plane where a section in the shape of a topped cone starts.
As described herein, the feed nozzle may advantageously be used to not only feed the biomass, but also to feed any additional hydrocarbon co-feed and/or any liquefying medium. In addition the feed nozzle may also be used as a mixer to mix any biomass with any additional hydrocarbon co-feed. The feed nozzle may further suitably serve to atomize any biomass and/or any additional hydrocarbon co-feed. Alternatively, the catalytic cracking reactor may comprise one or more other nozzles to provide any additional hydrocarbon co-feed and/or any liquefying medium.
The catalytic cracking reactor may comprise one or more feed nozzles for supplying the biomass. If two or more feed nozzles are used to supply the biomass, preferably at least one, but more preferably all such feed nozzles for supplying biomass are located between the second level and the fluid connection between the first section and the second section.
The one or more feed nozzle(s) may be any feed nozzle(s) known to be suitable by the person skilled in the art. Preferably the feed nozzle is a bottom entry feed nozzle or a side entry feed nozzle. If two or more feed nozzles are used, also a combination of one or more bottom entry feed nozzles and/or one or more side entry feed nozzles may be used. By a bottom entry feed nozzle is herein preferably understood a feed nozzle protruding the catalytic cracking reactor from the bottom. By a side entry feed nozzle is herein preferably understood a feed nozzle protruding the catalytic cracking reactor via a side wall. Preferably the catalytic cracking reactor comprises at least one bottom entry feed nozzle. More preferably such a bottom entry feed nozzle is the only feed nozzle supplying biomass to a first section.
In one embodiment, preferably, the biomass is contacted with the catalytic cracking catalyst at a temperature in the range from equal to or more than 450° C., more preferably from equal to or more than 480° C., most preferably from equal to or more than 500° C., to equal to or less than 800° C., more preferably equal to or less than 750° C., most preferably equal to or less than 680° C. If the temperature varies throughout the catalytic cracking reactor, the highest temperature in any catalytic cracking reactor is intended.
In another embodiment, the biomass is preferably contacted with the catalytic cracking catalyst at a pressure in the range from equal to or more than 0.05 MegaPascal to equal to or less than 1.0 MegaPascal, more preferably from equal to or more than 0.1 MegaPascal to equal to or less than 0.6 MegaPascal.
In one embodiment, the total average residence time of the biomass in the catalytic cracking reactor preferably lies in the range from equal to or more than 1 second, more preferably equal to or more than 1.5 seconds and even more preferably equal to or more than 2 seconds to equal to or less than 10 seconds, preferably equal to or less than 5 seconds and more preferably equal to or less than 4 seconds. Residence time as referred to in this patent application is based on the vapour residence at outlet conditions, that is, residence time includes not only the residence time of a specified feed but also the residence time of its conversion products.
In one embodiment, the weight ratio of catalyst to feed (that is the total feed of biomass and any optional additional hydrocarbon co-feed)—herein also referred to as catalyst:feed ratio—preferably lies in the range from equal to or more than 1:1, more preferably from equal to or more than 2:1 and most preferably from equal to or more than 3:1 to equal to or less than 150:1, more preferably to equal to or less than 100:1, most preferably to equal to or less than 50:1.
The catalytic cracking catalyst can be any catalyst known to the skilled person to be suitable for use in a cracking process. Preferably, the catalytic cracking catalyst comprises a zeolitic component. In addition, the catalytic cracking catalyst can contain an amorphous binder compound and/or a filler. Examples of the amorphous binder component include silica, alumina, titania, zirconia and magnesium oxide, or combinations of two or more of them. Examples of fillers include clays (such as kaolin).
The zeolite is preferably a large pore zeolite. The large pore zeolite includes a zeolite comprising a porous, crystalline aluminosilicate structure having a porous internal cell structure on which the major axis of the pores is in the range of 0.62 nanometer to 0.8 nanometer. The axes of zeolites are depicted in the ‘Atlas of Zeolite Structure Types’, of W. M. Meier, D. H. Olson, and Ch. Baerlocher, Fourth Revised Edition 1996, Elsevier, ISBN 0-444-10015-6. Examples of such large pore zeolites include FAU or faujasite, preferably synthetic faujasite, for example, zeolite Y or X, ultra-stable zeolite Y (USY), Rare Earth zeolite Y (=REY) and Rare Earth USY (REUSY). According to the present invention USY is preferably used as the large pore zeolite.
The catalytic cracking catalyst can also comprise a medium pore zeolite. The medium pore zeolite that can be used according to the present invention is a zeolite comprising a porous, crystalline aluminosilicate structure having a porous internal cell structure on which the major axis of the pores is in the range of 0.45 nanometer to 0.62 nanometer. Examples of such medium pore zeolites are of the MFI structural type, for example, ZSM-5; the MTW type, for example, ZSM-12; the TON structural type, for example, theta one; and the FER structural type, for example, ferrierite. According to the present invention, ZSM-5 is preferably used as the medium pore zeolite.
According to another embodiment, a blend of large pore and medium pore zeolites may be used. The ratio of the large pore zeolite to the medium pore size zeolite in the cracking catalyst is preferably in the range of 99:1 to 70:30, more preferably in the range of 98:2 to 85:15.
In one embodiment, the catalytic cracking catalyst is suitably contacted in a cocurrent-flow with the biomass. In another embodiment, preferably the catalytic cracking catalyst is separated from the one or more cracked products after use; regenerated in a regenerator; and reused in the catalytic cracking reactor. In yet another embodiment, preferably the catalytic cracking reactor is part of a catalytic cracking unit. More preferably the catalytic cracking reactor is a fluid catalytic cracking reactor that is part of a so-called fluid catalytic cracking (FCC) unit.
In a preferred embodiment, there is provided a fluid catalytic cracking process comprising a) a fluid catalytic cracking step comprising contacting a biomass with a fluid catalytic cracking catalyst at a temperature of more than 400° C. in a fluid catalytic cracking reactor to produce a product stream containing one or more cracked products and a spent fluid catalytic cracking catalyst, wherein the fluid catalytic cracking reactor comprises: a first section; a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction; a third section having a fluid connection to and located downstream of the second section; a catalyst supply pipe being connected to the first section for supplying the fluid catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and a feed nozzle having a feed nozzle outlet for supplying the biomass to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
The process further comprises b) a separation step comprising separating the one or more cracked products from the spent fluid catalytic cracking catalyst; c) a regeneration step comprising regenerating spent fluid catalytic cracking catalyst to produce a regenerated fluid catalytic cracking catalyst, heat and carbon dioxide; and d) a recycle step comprising recycling the regenerated fluid catalytic cracking catalyst to the fluid catalytic cracking step.
The fluid catalytic cracking step is preferably carried out as described herein before. The separation step is preferably carried out with the help of one or more cyclone separators and/or one or more swirl tubes. In addition the separation step may further comprise a stripping step. In such a stripping step the spent fluid catalytic cracking catalyst may be stripped to recover the products absorbed on the spent fluid catalytic cracking catalyst before the regeneration step. These products may be recycled and added to the cracked product stream obtained from the fluid catalytic cracking step.
The regeneration step preferably comprises contacting the spent fluid catalytic cracking catalyst with an oxygen containing gas in a regenerator at a temperature of equal to or more than 550° C. to produce a regenerated catalytic cracking catalyst, heat and carbon dioxide. During the regeneration, coke that can be deposited on the catalyst as a result of the catalytic cracking reaction is burned off to restore the catalyst activity. The regenerated fluid catalytic cracking catalyst can be recycled to the fluid catalytic cracking step.
In one embodiment, a product stream containing one or more cracked products is produced. In a preferred embodiment this product stream is subsequently fractionated to produce one or more product fractions. The one or more product fraction(s) may advantageously be used as biofuel component and/or biochemical component.
Certain embodiments are further illustrated by the following non-limiting figures.
In example 1 and comparative examples A and B, a fluid catalytic cracking reactor was used to catalytically crack a feed mixture containing 5 weight parts of a partially deoxygenated pyrolysis oil derived from a biomass material and 95 weight parts of a petroleum derived vacuum gas oil.
The fluid catalytic cracking reactor had a length of about 5.5 meters. Further the fluid catalytic cracking reactor comprised a third section with an essentially constant inner diameter of about 16 mm (also referred to as riser reactor standpipe); a second conically shaped section connecting the third section with a first section (also referred to as cone section); and a first section having an essentially constant inner diameter of about 26 mm (also referred to as liftpot). The sections were co-axially arranged around the same essentially vertical axis. The feed mixture was supplied to the fluid catalytic cracking reactor
In the fluid catalytic cracking reactor the feed mixture was contacted with a equilibrium catalyst containing Rare Earth Ultra Stable Y zeolite (ReUSY) at a temperature of about 520° C. The feed rate for the feed mixture was about 2.0 kilograms per hour. A catalyst to feed mixture weight ratio of about 8 was used, resulting in a catalyst supply rate of about 16 kilograms catalyst per hour. The fluid catalytic cracking reactor was operated for a fixed number of hours. For each example the residence time of the feed mixture in the fluid catalytic cracking reactor was about 2 seconds.
The extent of coking was examined by the eye and by examining the differential pressure. For example 1, the nozzle was arranged as illustrated in
Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
Claims
1. A process for converting a biomass comprising
- contacting a biomass with a catalytic cracking catalyst at a temperature of more than 400° C. in a catalytic cracking reactor to produce a product stream containing one or more cracked products, and
- supplying a biomass to the reactor via a feed nozzle having a feed nozzle outlet located between a first section and a second section of the reactor and downstream of an opening of a catalyst supply pipe connected to the first section, wherein the second section comprises a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction.
2. The process of claim 1, wherein the biomass comprises a pyrolysis oil derived from a biomass material.
3. The process of claim 2, wherein the pyrolysis oil is a pyrolysis oil derived from a cellulosic or lignocellulosic material.
4. The process of claim 2, wherein the pyrolysis oil is an at least partially deoxygenated pyrolysis oil.
5. The process of claim 1, wherein the first section comprises an essentially constant inner diameter.
6. The process of claim 1, wherein the reactor comprises a third section having a fluid connection to and located downstream of the second section, said third section comprises an essentially constant inner diameter that is smaller than the smallest inner diameter of the first section.
7. The process of claim 1, the reactor comprises a third section having a fluid connection to and located downstream of the second section, said third section comprises an inner diameter which increases in a downstream direction, and wherein the most upstream inner diameter of the third section is smaller than the smallest inner diameter of the first section.
8. The process of claim 1, wherein the reactor further comprises a catalyst supply pipe connected to a fluid passage in a side wall of the first section.
9. The process of claim 1, wherein the catalytic cracking reactor is a fluid catalytic cracking reactor and the catalytic cracking catalyst is a fluid catalytic cracking catalyst.
10. The process of claim 1, wherein the catalytic cracking reactor is a riser reactor.
11. The process of claim 1 further comprising supplying an additional hydrocarbon co-feed to the first section.
12. The process of claim 1 further comprising supplying a fluidizing medium to the first section to fluidize the catalytic cracking catalyst and/or the biomass, wherein the fluidizing medium flows from the first section in a downstream direction to the third section.
13. The process of claim 12, wherein the fluidizing medium comprises at least one of steam, nitrogen, liquefied petroleum gas, gasoline, diesel, kerosene or naphtha.
14. A catalytic cracking reactor comprising
- a first section;
- a second section having a fluid connection to and located downstream of the first section, the second section having an inner diameter which decreases in a downstream direction;
- a third section having a fluid connection to and located downstream of the second section;
- a catalyst supply pipe being connected to the first section for supplying a fluid catalytic cracking catalyst to said first section between a first level and a second level, said second level being located downstream of the first level; and
- a feed nozzle having a feed nozzle outlet for supplying a feed to the reactor, the feed nozzle outlet being located between the second level and the fluid connection between the first section and the second section.
15. The reactor of 14, further comprising
- a fluidizing medium supply and/or an additional hydrocarbon-cofeed supply having an outlet in the first section.
16. The reactor of claim 14, wherein the first section comprises an essentially constant inner diameter.
17. The reactor of claim 14, wherein the third section comprises an essentially constant inner diameter that is smaller than the smallest inner diameter of the first section.
18. The reactor of claim 14, wherein the third section comprises an inner diameter which increases in a downstream direction, and wherein the most upstream inner diameter of the third section is smaller than the smallest inner diameter of the first section.
Type: Application
Filed: Oct 22, 2013
Publication Date: May 1, 2014
Applicant: SHELL OIL COMPANY (Houston, TX)
Inventors: Gang WANG (Beijing), Jinsen GAO (Beijing), Yantao BI (Beijing)
Application Number: 14/060,249
International Classification: C10L 1/18 (20060101);
