Title of Invention

A PROCESS FOR CONVERTING A HYDROCARBONACEOUS FEEDSTOCK INTO LOWER BOILING MATERIALS

Abstract

57) Abstract:- The present invention provides a process for converting a hydrocarbonaceous feedstock (1) into lower boiling materials comprising the steps of: (a) contacting the feedstock (1) at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A to form hydrocracked product (3), (b) separating at least part of the hydrocracked product (3) of step (a) by means of distillation into at least one hydrocracked distillate (7) having a 5% atmospheric boiling point of> O°C and a 95% atmospheric boiling point of < 160° C, and at least one hydrocracked distillate (8,9,10) having a 95% atmospheric boiling point of > 200°C, and (c) contacting at least part ofthe at least one hydrocracked distillate (7) having a 5% atmospheric boiling point of >0°C and a 95% atmospheric boiling point of < 160°C at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst B comprising a molecular sieve. PRICE: THIRTY RUPEES.

Full Text

The present invention relates to hydrocarbon conversion processes involving catalytic hydrocracking. Catalytic hydrocracking is well established in the art and generally involves contacting heavy hydrocarbons, e.g. vacuum gas oils, with hydrogen in the presence of a bifunctional catalyst which is capable of simultaneously cracking heavy hydrocarbons into lighter hydrocarbons and also hydrogenating olefinic and aromatic compounds to paraffins and naphthenes. The products of catalytic hydrocracking include gaseous material such as methane, ethane and liquefied petroleum gas (LPG, a mixture of C3-C4 hydrocarbons), naphtha, middle distillates such as kerosine, jet fuel, diesel oils and heating oils, and hydro wax. There has been a great deal of work carried out over the years to develop catalytic hydrocracking processes that exhibit improved selectivity for middle distillates with minimum formation of gaseous material, i.e. to develop processes whose product slates contain low amounts of gaseous material and high amounts of middle distillates. However, such a product slate is not always desired or required. Indeed, in some countries around the world, particularly in the developing countries, there is considerable demand not only for middle distillates but also for liquefied petroleum gas (LPG) which is used primarily as a domestic cooking fuel. The existing catalytic hydrocracking processes which are designed specifically to minimize the formation of gaseous material are unable satisfactorily to meet such a demand and a new process is required. Therefore, in accordance with the present invention, there is provided a process for converting a hydrocarbonaceous feedstock into lower boiling materials comprising the steps of: (a) contacting the feedstock at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A to form hydrocracked product, (b) separating at least part of the hydrocracked product of step (a) by means of distillation into at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0°C and a 95% atmospheric boiling point of a 95% atmospheric boiling point of > 200°C, and (c) contacting at least part of the at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0°C and a 95% atmospheric boiling point of with hydrogen in the presence of a hydrocracking catalyst B comprising a molecular sieve. The hydrocarbonaceous feedstocks useful in the present process include gas oils, cooker gas oils, vacuum gas oils, deasphalted oils, fractions (e.g. gas oil and wax fractions) prepared using a Fischer-Tropic synthesis process, long residues, catalytically cracked cycle oils, thermally or catalytically cracked gas oils, and sinecures, optionally originating from tar sands, shale oils, residue upgrading processes or biomass. Combinations of various hydrocarbon oils may also be employed. The hydrocarbonaceous feedstock will generally be such that at least 50%w (per cent by weight) has a boiling point above 370°C. Nitrogen or sulphur contents in the hydrocarbonaceous feedstock are not critical. The feedstock may have a nitrogen content of up to 5000 ppmw (parts per million by weight) and a sulphur content of up to 6%w (per cent by weight). Typically, nitrogen contents are in the range from 250 to 2000 ppmw and sulphur contents are in the range from 0.2 to 5%w. It is possible and may sometimes be desirable to subject part or all of the feedstock to a pretreatment, for example, hydrodenitrogenation, hydrodesulphurisation or hydrodemetallisation, methods for which are known in the art. In step (a) of the process, the hydrocarbonaceous feedstock is contacted at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A to form hydrocracked product. It is possible, and may indeed be desirable, to use more than one such catalyst (e.g. two different hydrocracking catalysts A) in step (a), in which case step (a) is conveniently carried out in a stacked bed reactor. The reaction temperature is preferably in the range from 250 to 500°C, more preferably from 300 to 450°C and especially from 350 to 450°C. The total pressure in step (a) is preferably in the range from 5 x 106 Pa (50 bar) to 3 x lo6 Pa (300 bar) , more preferably from 7.5 x 10. Pa (75 bar) to 2.5 x lO". Pa (250 bar) and even more preferably 1 x lO6 Pa (100 bar) to 2 x lO. Pa (200 bar). The hydrogen partial pressure in step (a) is preferably in the range from 2.5 x 10 Pa (25 bar) to 2.5 X lo'' Pa (250 bar), more preferably from 5 x 106 Pa (50 bar) to 2 X lo6 Pa (200 bar) and still more preferably from 6 x 106 Pa (60 bar) to 1.8 x lO6 Pa (180 bar). A space velocity in the range preferably from 0.1 to 10, more preferably from 0.2 to 8, and especially from 0.5 to 5, kg fresh feedstock per litter catalyst A per hour (kg.l"l.h-1) is used. Furthermore, total gas rates (gas/feed ratios) in the range from 100 to 5000 Nl/kg are conveniently employed. Preferably, the total gas rate employed is in the range from 250 to 2500 Nl/kg. The hydrocracking catalyst A comprises an acidic cracking component and a hydrogenation component and is preferably middle distillate selective. The acidic cracking component may be a porous, amorphous inorganic oxide selected, e.g., from alumina, silica, silica-alumina, titania, zirconia and mixtures thereof, but is preferably a molecular sieve. Examples of suitable molecular sieves include crystalline aluminosilicates, crystalline aluminophosphates, crystalline silicoaluminophosphates and crystalline borosilicates. Preferred are the crystalline aluminosilicates or zeolites, notably zeolite beta or the mordenite-type zeolites or the faujasite-type zeolites, e.g. zeolite X and zeolite Y. A particularly preferred acidic cracking component is an ultrastable zeolite Y (USY zeolite), or a very ultrastable zeolite Y (VUSY zeolite), e.g. as taught from any one of EP-A-247 678, EP-A-247 679, US-A-4 401 556, GB-A-2 014 970, GB-A-2 114 594 and FR-A-2 563 445 (corresponding to US-A-4 738 941). For example, the VUSY zeolite of EP-A-247 678 or EP-A-247 679 is characterised by a unit cell size below 2.445nm (24.45 Angstroms) or 2.435 nm (24.35 Angstroms), a degree of crystalloid which is at least retained at increasing Si02/Al203 molar ratios, a water adsorption capacity (at 25°C and a p/p© value of 0.2) of at least 8%w of the zeolite and a pore volume of at least 0.25 ml/g wherein between 10% and 60% of the total pore volume is made up of pores having a diameter of at least 8 nm. (V)USY zeolites may be prepared from sodium zeolite Y by applying one or more ammonium ion exchanges followed by steam calcination. They may further be subjected to a so-called elimination technique to reduce the amount of alumina present. (V)USY zeolites generally have low sodium oxide contents, e.g. of less than 1%, and unit cell sizes in the range from 2.42 to 2.46 nm (24.2 to 24.6 Angstroms). The hydrogenation component is preferably selected from Group 6B (e.g. molybdenum and tungsten) and Group 8 metals (e.g. cobalt, nickel, platinum and palladium), their oxides and sulphides. The hydrogenation component more preferably comprises molybdenum and/or tungsten in combination with cobalt and/or nickel. Particularly preferred combinations are nickel/tungsten and nickel/molybdenum. Very advantageous results are obtained when the metals are used in the sulphate form. The hydrogenation component may be present in the catalyst in an amount of up to 50 parts by weight, calculated as metal per 100 parts by weight of total catalyst. For example, the catalyst may contain from 2 to 40, more preferably from 5 to 25 and especially from 8 to 20, parts by weight of Group 6 metal(s) and/or from 0.05 to 10, especially from 0.5 to 8, parts by weight of Group 8 metal(s), calculated as metal per 100 parts by weight of total catalyst. When the acid cracking component is a molecular sieve, the hydrocracking catalyst A preferably further comprises a binder, e.g. in an amount from 10 to 98 %w, preferably from 50 to 96 %w, based on the total dry weight of molecular sieve and binder. Examples of suitable binders include alumina, silica, silica-alumina, magnesia, zirconia, titania or mixtures thereof. Alumina is most preferred. The hydrocracking catalyst A may be prepared in accordance with techniques conventional in the art. For example, a catalyst comprising a molecular sieve, hydrogenation component and binder may conveniently be prepared by a process comprising co-mulling the molecular sieve and binder in the presence of water and optionally a peptising agent, extruding the resulting mixture into pellets, acclaiming the pellets and then impregnating the claimed pellets with one or more solutions of Group 6B and/or Group 8 metal salts. Alternatively, the molecular sieve and binder may be co-mulled in the presence of one or more solutions of Group 6B and/or Group 8 metal salts and optionally a peptising agent, and the mixture so formed extruded into pellets. The pellets may then be claimed. Examples of hydrocracking catalysts useful in step (a) of the present process are to be found in the Oil and Gas Journal, dated 11 October 1993, pages 41 to 68. The hydrocracking catalyst A is preferably a catalyst selected from: HC33, HC22, DHC32, DHCIOO and DHC8 (each of which is commercially available from UOP/Unocal), HYC-642 (commercially available from Pro-Catalyze), Z603 and Z713 (both commercially available from Soloist International) and KC2200, KC2300 and KC2600 (commercially available from Akzo Nobel). If a pretreatment of the hydrocarbonaceous feedstock is required, this is preferably carried out simultaneously with the hydrocracking of the feedstock according to step (a) of the present process, e.g. in a stacked bed reactor. Thus, the hydrocarbonaceous feedstock is first contacted with one or more pretreatment catalysts to effect hydrodenitrogenation and/or hydrodesulphurisation and/or hydrodemetallisation of the feedstock, and the feedstock thus treated is subsequently contacted with a catalyst of type A to effect hydrocracking thereof. Depending on the nature of the pretreatment, the pretreatment catalyst may also be a catalyst of type A, Pretreatment catalysts are known which have a dual hydrodenitrogenation and hydrodesulphurisation activity and such a catalyst may very conveniently be used in the present process. Examples of suitable pretreatment catalysts include KF843 commercially available from Akzo Nobel; C424, C411 and DN120 commercially available from Criterion Catalyst Company; HR348 and HR360 commercially available from Pro-Catalyze; and HCH and HCK commercially available from UOP/Unocal. Hydrocracked product is formed in step (a) of the present process. In step (b) of the process, at least part, preferably substantially all, of this hydrocracked product is separated by means of distillation into at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0°C and a 95% atmospheric boiling point of 200°C (e.g. a kerosine and/or gas oil fraction), the boiling points being those determined according to standard test method ASTM D 86. At least part, preferably substantially all, of the at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0°C and a 95% atmospheric boiling point of In a preferred aspect of the invention, the hydrocracked product of step (c) is separated together with the hydrocracked product of step (a) in step (b) of the process. A preferred hydrocracked distillate to use in step (c) is one having a 5% atmospheric boiling point of > 30°C and a 95% atmospheric boiling point of 90°C and a 95% atmospheric boiling point of The reaction temperature in step (c) is preferably in the range from 250 to 450°C, more preferably from 3 00 to 450°C and especially from 350 to 420°C. The total pressure in step (c) is preferably in the range from 5 x 10. Pa (50 bar) to 3 x lO". Pa (300 bar) , more preferably from 7.5 x 10. Pa (75 bar) to 2.5 x lo". Pa (250 bar) and even more preferably 1 x lO'. Pa (100 bar) to 2 x lO. Pa (200 bar). The hydrogen partial pressure in step (c) is preferably in the range from 2.5 x 10. Pa (25 bar) to 2.5 x 10'7 Pa (250 bar), more preferably from 5 x 10. Pa (50 bar) to 2 x lo". Pa (200 bar) and still more preferably from 6 x 10. Pa (60 bar) to 1.8 x lO. Pa (180 bar). A space velocity in the range preferably from 0.5 to 5, more preferably from 1 to 4, and especially from 2 to 3, kg hydrocracked distillate(s) per liter catalyst B per hour (kg.l"l.h"l) is used. The term 'hydrocracked distillate(s)' in this context is also intended to include mixtures of one or more hydrocracked distillates with, for example, straight-run naphtha and thus the space velocity quoted is for the total fresh feed used in step (c). Furthermore, total gas rates (gas/feed ratios) in the range from 250 to 4000 Nl/kg are conveniently employed. Preferably, the total gas rate employed is in the range from 500 to 2000 Nl/kg. The hydrocracking catalyst B comprises, as acidic cracking component, a molecular sieve having a pore diameter preferably in the range from 0.4 to 0.8 nm (4 to 8 Angstroms), more preferably in the range from 0.5 to 0.7 nm (5 to 7 Angstroms). The catalyst further comprises a hydrogenation component and, optionally, a binder. One or more hydrocracking catalysts B may be used in step (c) as required. If more than one such catalyst is used, step (c) is conveniently carried out in a stacked bed reactor. Examples of molecular sieves that may be used in catalyst B and that have a pore diameter in the range from 0.4 to 0.8 nm (4 to 8 Angstroms) include crystalline aluminosilicates or zeolites (e.g. reignite, furrieries, theta, beta, V(USY) as described above and ZSM-type zeolites such as ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35 and ZSM-38), crystalline aluminophosphates (e.g. ALPO-11 described in US-A-4 310 440), crystalline silicoaluminophosphates (e.g. SAPO-11 described in US-A-4 440 871) and crystalline borosilicates (e.g. as described in US-A-4 254 2 97). Preferred are the crystalline aluminosilicates or zeolites. The hydrogenation component is preferably selected from Group 6B (e.g. molybdenum and tungsten) and Group 8 metals (e.g. cobalt, nickel, platinum and palladium), their oxides and sulphides. The hydrogenation component may comprise one or more of molybdenum, tungsten, cobalt and nickel, preferably in the sulphate form, but is advantageously platinum or palladium metal. The hydrogenation component may be present in the catalyst in an amount of up to 50 parts by weight, calculated as metal per 100 parts by weight of total catalyst. For example, the catalyst may contain from 2 ♦■o 40, more preferably from 5 to 25 and especially from 8 3 20, parts by weight of Group 6 metal(s) and/or from .05 to 10, especially from 0.5 to 8, parts by weight of croup 8 metal(s), calculated as metal per 100 parts by sight of total catalyst. The binder, if present, in catalyst B may be any of lose mentioned above for catalyst A. The binder is referable used in an amount from 10 to 98 %w, irticularly from 50 to 96 %w, based on the total dry 2ight of molecular sieve and binder. The hydrocracking catalyst B may be prepared by thuds well known in the art. In a preferred embodiment of the invention, the /•drocracking catalyst B comprises as, acidic cracking moment, zeolite ZSM-12 and, as hydrogenation moment, palladium metal. Such a catalyst may )nveniently be prepared by ion-exchanging'zeolite ZSM-12 .the a palladium solution, e.g. Pd(NH3)4Cl2 in NH4NO3 dilution. The ion-exchanged zeolite thus obtained is Len dried, extruded into pellets, claimed and reduced >ing hydrogen gas. The present invention also provides a hydrocracking rocs which comprises contacting at least one '■drocracked distillate having a 5% atmospheric boiling into of > 0°C and a 95% atmospheric boiling point of 160°C at elevated temperature and elevated pressure .the hydrogen in the presence of a hydrocracking catalyst as defined above. The process conditions used are •wisely the same as those described for step (c) above. Accordingly the present invention provides a process for converting a hydrocarbonaceous feedstock into lower boiling materials comprising the steps of a) contacting the feedstock at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A to form hydrocracked product, b) separating at least part of the hydrocracked product of step (a) by means of distillation into at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0*. C and a 95% atmospheric boiling point of O*' C and a 95% atmospheric boiling point of The present invention will now be further described with reference to the accompanying drawings in which; Figure 1 illustrates schematically an embodiment of the present process. In Figure 1, a hydrocarbonaceous feedstock 1 is passed, together with recycle stream 11 discussed_ hereinafter, to a hydrocracking unit 2 where it is contacted at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A as defined above to form hydrocracked product 3. The hydrocracked product 3 together with a second hydrocracked product 13 discussed hereinafter are passed, with cooling, via a gas/liquid separator 4 to a ' . distillation unit 5 where they are separated into a gaseous stream 6 containing predominantly C3_-C4 hydrocarbons, a naphtha-containing hydrocracked distillate stream 7 having a 5% atmospheric boiling point of > 0°C and a 95% atmospheric boiling point of 200°C, and a recycle stream 11 containing heavy hydrocarbons which is combined with the feedstock 1 and sent to the hydrocracking unit 2. The naphtha-containing hydrocracked distillate stream 7 is conveyed to a hydrocracking unit 12 where it is contacted at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst B as defined above to form hydrocracked product 13 containing predominantly C3-C4 hydrocarbons useful for the production of liquefied petroleum gas. A typical product slate obtained from the process of the present invention is compared in Table I below with that obtained from a known middle distillate selective hydrocracking process. It will be observed from Table I that by using the process of the present invention, liquefied petroleum gas (LPG) and middle distillates can be produced simultaneously in high yields. Wt CLAIM: 1. A process for converting a hydrocarbonaceous feedstock into lower boiling materials comprising the steps of: a) contacting the feedstock at elevated temperature and elevated pressure with hydrogen in the presence of a hydrocracking catalyst A to form hydrocracked product, b) separating at least part of the hydrocracked product of step (a) by means of distillation into at least one hydrocracked distillate having a 5% atmospheric boiling point of > 0° C and a 95% atmospheric boiling point of 0°C and a 95% atmospheric boiling point of 2. The process according to claim 1, wherein step (a) is carried out at a temperature in the range from 250 to 500°C and a total pressure in the range from 5 x 10^ to 3 x 10^ Pa. 3. The process according to claim 2, wherein a space velocity in the range from 0.1 to 10 kg fresh feedstock per litre catalyst A per hour (kg.1-1.h-1is used. 4. The process according to any one of claims 1 to 3,wherein catalyst A comprises a molecular sieve and a hydrogenation component selected from Group 6B and Group 8 metals, their oxides and sulphides. 5. The process according to claim 4, wherein the molecular sieve is a zeolite. 6. The process according to claim 5, wherein the molecular sieve is a mordenite-type of faujasite-type zeolite. 7. The process according to any one of claims 4 to 6, wherein catalyst A comprises a binder. 8. The process according to any one of the preceding claims, wherein step (c) is carried out a temperature in the range from 250 to 450*^0 and a total pressure in the range from 5 x 10^ to 3 x 10^ Pa. 9. The Process according to claim 8, wherein a space velocity in the range from 0.5 to 5 kg hydrocracked distillate (s) per litre catalyst B per hour (kg.1. .h-1) is used. 10. The process according to any one of the preceding claims, wherein catalyst B comprises a molecular sieve having a pore diameter in the range from 0.4 to 0.8 nm. 11. The process according to any one of the preceding claims, wherein catalyst B comprises a zeolite as molecular sieve. 12. The process according to claim II, wherein the zeolite is ZSM- 5, ZSM-12, ferrierite or zeolite beta. 13. The process according to any one of the preceding claims, wherein catalyst B comprises a hydrogenation component selected from Group 6B and Group 8 metals, their oxides and sulphides and, optionally a binder. 14. A process for converting a hydrocarbonaceous feedstock into lower boiling materials, substantially as herein described with reference to the accompanying drawings.

Documents:

1562-mas-1995 abstract.pdf

1562-mas-1995 claims.pdf

1562-mas-1995 correspondence-others.pdf

1562-mas-1995 correspondence-po.pdf

1562-mas-1995 description(complete).pdf

1562-mas-1995 drawings.pdf

1562-mas-1995 form-1.pdf

1562-mas-1995 form-26.pdf

1562-mas-1995 form-4.pdf

1562-mas-1995 form-6.pdf

1562-mas-1995 form-9.pdf

1562-mas-1995 petition.pdf