ZA200206891B - Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process. - Google Patents
Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process. Download PDFInfo
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- ZA200206891B ZA200206891B ZA200206891A ZA200206891A ZA200206891B ZA 200206891 B ZA200206891 B ZA 200206891B ZA 200206891 A ZA200206891 A ZA 200206891A ZA 200206891 A ZA200206891 A ZA 200206891A ZA 200206891 B ZA200206891 B ZA 200206891B
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- Prior art keywords
- propylene
- products
- olefins
- catalyst
- paraffins
- Prior art date
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- 238000000034 method Methods 0.000 title claims description 49
- 150000001336 alkenes Chemical class 0.000 title claims description 37
- -1 polypropylene Polymers 0.000 title claims description 20
- 239000004743 Polypropylene Substances 0.000 title claims description 12
- 229920001155 polypropylene Polymers 0.000 title claims description 12
- 238000004231 fluid catalytic cracking Methods 0.000 title description 10
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 42
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 42
- 239000003054 catalyst Substances 0.000 claims description 40
- 239000010457 zeolite Substances 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 18
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 12
- 229910021536 Zeolite Inorganic materials 0.000 claims description 11
- 229930195733 hydrocarbon Natural products 0.000 claims description 10
- 150000002430 hydrocarbons Chemical class 0.000 claims description 10
- 239000011148 porous material Substances 0.000 claims description 9
- 239000004215 Carbon black (E152) Substances 0.000 claims description 8
- 230000000379 polymerizing effect Effects 0.000 claims description 3
- 239000000047 product Substances 0.000 description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
- 239000003921 oil Substances 0.000 description 8
- 238000006116 polymerization reaction Methods 0.000 description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 6
- 239000005977 Ethylene Substances 0.000 description 6
- 229910052809 inorganic oxide Inorganic materials 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- 241000282326 Felis catus Species 0.000 description 4
- 239000000571 coke Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 229910000323 aluminium silicate Inorganic materials 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 241000894007 species Species 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical class O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005194 fractionation Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000006384 oligomerization reaction Methods 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- RYPKRALMXUUNKS-UHFFFAOYSA-N 2-Hexene Natural products CCCC=CC RYPKRALMXUUNKS-UHFFFAOYSA-N 0.000 description 1
- BZLVMXJERCGZMT-UHFFFAOYSA-N Methyl tert-butyl ether Chemical compound COC(C)(C)C BZLVMXJERCGZMT-UHFFFAOYSA-N 0.000 description 1
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 description 1
- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- 238000005899 aromatization reaction Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001680 bayerite Inorganic materials 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000004523 catalytic cracking Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 238000005235 decoking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 229910001648 diaspore Inorganic materials 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 238000006317 isomerization reaction Methods 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 238000003541 multi-stage reaction Methods 0.000 description 1
- 229910001682 nordstrandite Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- JTXAHXNXKFGXIT-UHFFFAOYSA-N propane;prop-1-ene Chemical compound CCC.CC=C JTXAHXNXKFGXIT-UHFFFAOYSA-N 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- NUMQCACRALPSHD-UHFFFAOYSA-N tert-butyl ethyl ether Chemical compound CCOC(C)(C)C NUMQCACRALPSHD-UHFFFAOYSA-N 0.000 description 1
- 238000006276 transfer reaction Methods 0.000 description 1
- 239000003039 volatile agent Substances 0.000 description 1
Description
PROCESS FOR PRODUCING POLYPROPYLENE
FROM C; OLEFINS SELECTIVELY PRODUCED : IN A FLUID CATALYTIC CRACKING PROCESS , 5
The present invention relates to a process for producing polypropylene from C; olefins selectively produced from a catalytically cracked or thermally cracked naphtha stream.
The need for low-emissions fuels has created an increased demand for light olefins used use in alkylation, oligomerization, MTBE, and ETBE synthesis processes. In addition, a low cost supply of light olefins, particularly propylene, continues to be in demand to serve as feed for polyolefins production, particularly polypropylene production.
Fixed bed processes for light paraffin dehydrogenation have recently attracted renewed interest for increasing olefins production. However, these types of processes typically require relatively large capital investments as well as high operating costs. It is therefore advantageous to increase olefins yield using processes, which require relatively small capital investment. It would be particularly advantageous to increase olefins yield in catalytic cracking
Processes.
A problem inherent in producing olefins products using FCC units is that \ the process depends on a specific catalyst balance to maximize production of vy, 25 light olefins while also achieving high conversion of the 650° F + (~340°C +) ‘ feed components. In addition, even if a specific catalyst balance can be maintained to maximize overall olefins production, olefins selectivity is generally low because of undesirable side reactions, such as extensive cracking, isomerization, aromatization and hydrogen transfer reactions. Light saturated y gases produced from undesirable side reactions result in increased costs to ’ recover the desirable light olefins. Therefore, it is desirable to maximize olefins production in a process that allows a high degree of control over the selectivity to C, - C4 olefins that are processed and polymerized to form products such as polypropylene and polyethylene.
An embodiment of the present invention comprises a process for producing polypropylene comprising the steps of (a) contacting a naphtha feed containing less than 40 wt.% paraffins and between about 15 and about 70 wt.% olefins with a catalyst to form a cracked product, the catalyst comprising about 10 to about 50 wt.% of a crystalline zeolite having an average pore diameter less than about 0.7 nm, the reaction conditions including a temperature from about 500° to 650° C, a hydrocarbon partial pressure of 10 to 40 psia (70-280 kPa), a hydrocarbon residence time of 1 to 10 seconds, and a catalyst to feed ratio, by weight, of about 4 to 10, wherein no more than about 20 wt.% of paraffins are converted to olefins and wherein propylene comprises at least 90 mol.% of the total C; products; and, (b) separating the propylene from the cracked product and polymerizing the propylene to form polypropylene.
In another preferred embodiment of the present invention the catalyst is a
ZSM-5 type catalyst.
In still another preferred embodiment of the present invention the feed ‘ contains about 5 to 35 wt.% paraffins, and from about 20 to 70 wt.% olefins.
In yet another preferred embodiment of the present invention the reaction zone is operated at a temperature from about 525° C to about 600° C.
Vo DETAILED DESCRIPTION OF THE INVENTION
Suitable hydrocarbons feeds for producing the relatively high C,, Cs, and
C, olefins yields are those streams boiling in the naphtha range and containing less than about 40 wt.% paraffins, preferably from about 5 wt.% to about 35 wt.%, more preferably from about 10 wt.% to about 30 wt.%, and most preferably from about 10 to 25 wt.% paraffins, and from about 15 wt.%, preferably from about 20 wt.% to about 70 wt.% olefins. The feed may also contain naphthenes and aromatics. Naphtha boiling range streams are typically those having a boiling range from about 65° F to about 430° F (18-225° C), preferably from about 65° F to about 300° F (18-150° C).
The naphtha feed can be a thermally-cracked or catalytically-cracked naphtha derived from any appropriate source, including fluid catalytic cracking (FCC) of gas oils and resids or delayed- or fluid-coking of resids. Preferably, the naphtha streams used in the present invention derive from the fluid catalytic cracking of gas oils and resids because the product naphthas are typically rich in olefins and/or diolefins and relatively lean in paraffins.
The process of the present invention is performed in a process unit comprising a reaction zone, a stripping zone, a catalyst regeneration zone, and a fractionation zone. The naphtha feed is fed into the reaction zone where it contacts a source of hot, regenerated catalyst. The hot catalyst vaporizes and cracks the feed at a temperature from about 500° C to 650° C, preferably from ) about 525° C to 600° C. The cracking reaction deposits coke on the catalyst, thereby deactivating the catalyst. The cracked products are separated from the coked catalyst and sent to a fractionator. The coked catalyst is passed through the stripping zone where volatiles are stripped from the catalyst particles with steam. The stripping can be preformed under low severity conditions to retain a
. greater fraction of adsorbed hydrocarbons for heat balance. The stripped catalyst ' is then passed to the regeneration zone where it is regenerated by burning coke on the catalyst in the presence of an oxygen containing gas, preferably air.
Decoking restores catalyst activity and simultaneously heats the catalyst to between about 650° C and about 750° C. The hot catalyst is then recycled to the reaction zone to react with fresh naphtha feed. Flue gas formed by burning coke in the regenerator may be treated for removal of particulates and for conversion of carbon monoxide. The cracked products from the reaction zone are sent to a fractionation zone where various products are recovered, particularly a Cs, fraction and a C, fraction.
While attempts have been made to increase light olefins yields in the FCC process unit itself, the practice of the present invention uses its own distinct process unit, as previously described, which receives naphtha from a suitable source in the refinery. The reaction zone is operated at process conditions that will maximize C, to C, olefins, particularly propylene, selectivity with relatively high conversion of Cs+ olefins. Catalysts suitable for use in the practice of the present invention are those which are comprising a crystalline zeolite having an average pore diameter less than about 0.7 nanometers (nm), said crystalline zeolite comprising from about 10 wt.% to about 50 wt.% of the total fluidized catalyst composition. It is preferred that the crystalline zeolite be selected from the family of medium-pore-size (< 0.7 nm) crystalline aluminosilicates, otherwise referred to as zeolites. Of particular interest are the medium-pore zeolites with a silica to alumina molar ratio of less than about 75:1, preferably less than about 50:1, and more preferably less than about 40:1, although some embodiments incorporate silica-to-alumina ratios greater than 40:1. The pore diameter, also referred to as effective pore diameter, is measured using standard adsorption techniques and hydrocarbonaceous compounds of known minimum
© WO 01/64760 PCT/US01/06684
N kinetic diameters. See Breck, Zeolite Molecular Sieves, 1974 and Anderson et al., J. Catalysis 58, 114 (1979), both of which are incorporated herein by reference.
Medium-pore-size zeolites that can be used in the practice of the present invention are described in “Atlas of Zeolite Structure Types,” eds. W.H. Meier and D.H. Olson, Butterworth-Heineman, Third Edition, 1992, which is hereby incorporated by reference. The medium-pore-size zeolites generally have a pore size from about 0.5 nm, to about 0.7 nm and include for example, MFI, MFS,
MEL, MTW, EUO, MTT, HEU, FER, and TON structure type zeolites (IUPAC
Commission of Zeolite Nomenclature). Non-limiting examples of such medium- pore-size zeolites, include ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM- 35, ZSM-38, ZSM-48, ZSM-50, silicalite, and silicalite 2. The most preferred is
ZSM-5, which is described in U.S. Patent Nos. 3,702,886 and 3,770,614. ZSM- 11 is described in U.S. Patent No. 3,709,979; ZSM-12 in U.S. Patent No. 3,832,449; ZSM-21 and ZSM-38 in U.S. Patent No. 3,948,758; ZSM-23 in U.S.
Patent No. 4,076,842; and ZSM-35 in U.S. Patent No. 4,016,245. All of the above patents are incorporated herein by reference. Other suitable medium- pore-size zeolites include the silicoaluminophosphates (SAPO), such as SAPO-4 and SAPO-11 which is described in U.S. Patent No. 4,440,871; chromosilicates; gallium silicates; iron silicates; aluminum phosphates (ALPO), such as ALPO- 11 described in U.S. Patent No. 4,310,440; titanium aluminosilicates (TASO), such as TASO-45 described in EP-A No. 229,295; boron silicates, described in
U.S. Patent No. 4,254,297, titanium aluminophosphates (TAPO), such as TAPO- 11 described in U.S. Patent No. 4,500,651; and iron aluminosilicates.
The medium-pore-size zeolites can include *“‘crystalline admixtures” which are thought to be the result of faults occurring within the crystal or crystalline area during the synthesis of the zeolites. Examples of crystalline ) ‘admixtures of ZSM-5 and ZSM-11 are disclosed in U.S. Patent No. 4,229,424, which is incorporated herein by reference. The crystalline admixtures are themselves medium-pore-size zeolites and are not to be confused with physical admixtures of zeolites in which distinct crystals of crystallites of different zeolites are physically present in the same catalyst composite or hydrothermal reaction mixtures.
The catalysts of the present invention are held together with an inorganic oxide matrix material component. The inorganic oxide matrix component binds the catalyst components together so that the catalyst product is hard enough to survive interparticle and reactor wall collisions. The inorganic oxide matrix can be made from an inorganic oxide sol or gel which is dried to “bind” the catalyst components together. Preferably, the inorganic oxide matrix is not catalytically active and will be comprising oxides of silicon and aluminum. Preferably, separate alumina phases are incorporated into the inorganic oxide matrix. Species of aluminum oxyhydroxides-y-alumina, boehmite, diaspore, and transitional aluminas such as a-alumina, B-alumina, y-alumina, 8-alumina, e-alumina, k-alumina, and p- alumina can be employed. Preferably, the alumina species is an aluminum trihydroxide such as gibbsite, bayerite, nordstrandite, or doyelite. The matrix material may also contain phosphorous or aluminum phosphate.
Process conditions include temperatures from about 500° C to about 650° : C, preferably from about 525° C to 600° C, hydrocarbon partial pressures from about 10 to 40 psia (70-280 kPa), preferably from about 20 to 35 psia (140-245 ’ kPa); and a catalyst to naphtha (wt/wt) ratio from about 3 to 12, preferably from about 4 to 10, where catalyst weight is total weight of the catalyst composite.
Preferably, steam is concurrently introduced with the naphtha stream into the reaction zone and comprises up to about 50 wt.% of the hydrocarbon feed. Also, : it is preferred that the feed residence time in the reaction zone be less than about 10 seconds, for example from about 1 to 10 seconds. These conditions will be such that at least about 60 wt.% of the Cs+ olefins in the naphtha stream are converted to C,4- products and less than about 25 wt.%, preferably less than about 20 wt.% of the paraffins are converted to C4- products, and that propylene comprises at least about 90 mol.%, preferably greater than about 95 mol.% of the total C; reaction products with the weight ratio of propylene/total C,- products greater than about 3.5.
Preferably, ethylene comprises at least about 90 mol.% of the C, products, with the weight ratio of propylene:ethylene being greater than about 4, and that the “full range” Cs+ naphtha product is enhanced in both motor and research octanes relative to the naphtha feed. It is within the scope of this invention to pre-coke the catalysts before introducing the feed to further improve the selectivity to propylene. It is also within the scope of this invention to feed an effective amount of single ring aromatics to the reaction zone to also improve the selectivity of propylene versus ethylene. The aromatics may be from an external source such as a reforming process unit or they may consist of heavy naphtha recycle product from the instant process.
The following examples are presented for illustrative purposes only and are not to be taken as limiting the present invention in any way.
EXAMPLES 1-12
The following examples illustrate the criticality of process operating conditions for maintaining chemical grade propylene purity with samples of cat naphtha cracked over ZCAT-40 (a catalyst that contains ZSM-5) which had been steamed at 1500° F (815°C) for 16 hrs to simulate commercial equilibrium.
Comparison of Examples | and 2 show that increasing Cat/Oil ratio improves ‘ propylene yield, but sacrifices propylene purity.
Comparison of Examples 3 and 4 and 5 and 6 shows reducing oil partial pressure greatly improves propylene purity without compromising propylene yield.
Comparison of Examples 7 and 8 and 9 and 10 shows increasing temperature improves both propylene yield and purity.
Comparison of Examples 11 and 12 shows decreasing cat residence time improves propylene yield and purity.
Example 13 shows an example where both high propylene yield and purity are obtained at a reactor temperature and cat/oil ratio that can be achieved using a conventional FCC reactor/regenerator design for the second stage.
TABLE 1
Feed Temp. Oil Res. CatRes. Wt% Wt% Propylene
Example Olefins, wt% °C CatQil Qilpsia Time, sec Time, sec Ci Cy Purity, % 1 38.6 566 4.2 36 0.5 43 11.4 0.5 95.8% 2 38.6 569 8.4 32 0.6 4.7 12.8 0.8 94.1% 3 22.2 510 8.8 18 1.2 8.6 8.2 1.1 88.2% 4 22.2 511 9.3 38 1.2 5.6 6.3 1.9 76.8% 38.6 632 16.6 20 1.7 98 16.7 1.0 94.4% 6 38.6 630 16.6 13 1.3 75 16.8 0.6 96.6% 7 22.2 571 5.3 27 0.4 0.3 6.0 0.2 96.8% 8 22.2 586 5.1 27 03 0.3 7.3 0.2 97.3% 9 22.2 511 9.3 38 1.2 5.6 6.3 1.9 76.8% 22.2 607 9.2 37 1.2 6.0 10.4 2.2 82.5% 11 22.2 576 18.0 32 1.0 9.0 9.6 4.0 70.6% 12 22.2 574 18.3 32 1.0 24 10.1 1.9 84.2% 13 38.6 606 8.5 22 1.0 7.4 15.0 0.7 95.5%
Table 1 Continued 5
Ratio of C;~ Ratio of C;~
Example Wt% GC,” Wt%GCy 0G; to Cy Wt% Cy 1 2.35 2.73 4.9 4.2 11.4 2 3.02 3.58 4.2 3.6 12.8 3 2.32 2.53 35 3.2 8.2 4 2.16 2.46 29 2.6 6.3 5 6.97 9.95 24 1.7 16.7 6 6.21 8.71 2.7 19 16.8 7 1.03 1.64 5.8 3.7 6.0 8 1.48 2.02 4.9 3.6 7.3 9 2.16 246 2.9 2.6 6.3 10 5.21 6.74 2.0 1.5 10.4 11 4.99 6.67 1.9 1.4 9.6 12 4.43 6.27 2.3 1.6 10.1 : 13 4.45 5.76 3.3 2.6 15.0
C; =CH4+ CH, + CoH
The above examples (1,2,7 and 8) show that C;/C,” >4 and C;7/C, > 3.5 can be achieved by selection of suitable reactor conditions.
EXAMPLES 14-17 * The cracking of olefins and paraffins contained in naphtha streams (e.g.,
FCC naphtha, coker naphtha) over small or medium-pore zeolites such as ZSM- can produce significant amounts of ethylene and propylene. The selectivity to 5 ethylene or propylene and selectivity of propylene to propane varies as a function of catalyst and process operating conditions. It has been found that propylene yield can be increased by co-feeding steam along with cat naphtha to the reactor. The catalyst may be ZSM-5 or other small or medium-pore zeolites.
Table 2 below illustrates the increase in propylene yield when 5 wt.% steam is co-fed with an FCC naphtha containing 38.8 wt% olefins. Although propylene yield increased, the propylene purity is diminished. Thus, other operating conditions may need to be adjusted to maintain the targeted propylene selectivity.
TABLE 2
Steam Temp. Oil Res. CatRes. Wt% Wt% Propylene
Example Co-feed C CatOil Oil psia Time, sec Time, sec Propylene Propane Purity, % 14 No 630 8.7 18 0.8 8.0 1.7 0.3 97.5%
Yes 631 88 22 1.2 6.0 13.9 0.6 95.9% 16 No 631 87 18 0.8 7.8 13.6 0.4 97.1% 15 17 Yes 632 84 22 1.1 6.1 14.6 0.8 94.8%
Light olefins resulting from the preferred process may be used as feeds for processes such as oligomerization, polymerization, co-polymerization, ter- polymerization, and related processes (hereinafter "polymerization") to form macromolecules. Such light olefins may be polymerized both alone and in combination with other species, in accordance with polymerization methods known in the art. In some cases it may be desirable to separate, concentrate, purify, upgrade, or otherwise process the light olefins prior to polymerization.
Propylene and ethylene are preferred polymerization feeds. Polypropylene and polyethylene are preferred polymerization products made therefrom.
Claims (20)
- CLAIMS:* 1. A process for producing polypropylene comprising the steps of: (a) contacting a naphtha feed containing less than about 40 wt.% paraffins and between about 15 and about 70 wt.% olefins with a catalyst to form a cracked product, the catalyst comprising about to about 50 wt.% of a crystalline zeolite having an average pore diameter less than about 0.7 nm, the reaction conditions including a temperature from about 500° C to 650° C, a hydrocarbon partial pressure of 10 to 40 psia, a hydrocarbon residence time of 1 to 10 10 seconds, and a catalyst to feed ratio, by weight, of about 4 to 10, wherein no more than about 20 wt.% of paraffins are converted to olefins and wherein propylene comprises at least 90 mol.% of the total C; products; and, (b) separating the propylene from the cracked product and polymerizing the propylene to form polypropylene.
- 2. The process of claim 1 wherein the crystalline zeolite is selected from the ZSM series.
- 3. The process of claim 2 wherein the crystalline zeolite is ZSM-5.
- 4. The process of claim 3 wherein propylene comprises at least 95 mol.% of the total C; products.
- 5. The process of claim 3 wherein the reaction temperature is from about ) 500° C to about 600° C.
- 6. The process of claim 3 wherein at least about 60 wt.% of the Cs + olefins * in the feed are converted to C,- products and less than about 25 wt.% of the paraffins are converted to C,- products.
- 7. The process of claim 6 wherein propylene comprises at least about 90 mol.% of the total C; products.
- 8. The process of claim 7 wherein the weight ratio of propylene to total C,- products is greater than about 3.5.
- 9. The process of claim 8 wherein the weight ratio of propylene to total C,- products is greater than about 4.0.
- 10. The process of claim 1 wherein said naphtha feed contains from about 5 to about 35 wt.% paraffins.
- 11. A process for producing polypropylene comprising the steps of: (a) contacting a naphtha feed containing less than about 40 wt.% paraffins and between about 15 and about 70 wt.% olefins with a catalyst to form a cracked product, the catalyst comprising a crystalline zeolite having an average pore diameter less than about0.7 nm, the reaction conditions including a temperature from about 500° C to 650° C, a hydrocarbon partial pressure of 10 to 40 psia, a hydrocarbon residence time of 1 to 10 seconds, and a catalyst to . 20 feed ratio, by weight, of about 4 to 10, wherein no more than about wt.% of paraffins are converted to olefins and wherein : propylene comprises at least 90 mol.% of the total C; products; and,(b) separating the propylene from the cracked product and polymerizing the propylene to form polypropylene.
- 12. The process of claim 10 wherein the crystalline zeolite is selected from the ZSM series. s
- 13. The process of claim 11 wherein the crystalline zeolite is ZSM-5.
- 14. The process of claim 10 wherein propylene comprises at least 95 mol.% of the total C; products.
- 15. The process of claim 12 wherein the reaction temperature is from about 500° C to about 600° C.
- 16. The process of claim 14 wherein at least about 60 wt.% of the Cs + olefins in the feed is converted to C4- products and less than about 25 wt.% of the paraffins are converted to Cs- products.
- 17. The process of claim 15 wherein the weight ratio of propylene to total C,- products is greater than about 3.5.
- 18. The process of claim 16 wherein the weight ratio of propylene to total Cz- products is greater than about 4.0.
- 19. The process of claim 11 wherein said naphtha feed contains from about 5 to about 35 wt.% paraffins.
- 20. The process of claim 1 or 11, substantially as herein described and exemplified. AMENDED SHEET
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US09/517,554 US6388152B1 (en) | 1998-05-05 | 2000-03-02 | Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process |
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ZA200206891A ZA200206891B (en) | 2000-03-02 | 2002-08-28 | Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process. |
ZA200206889A ZA200206889B (en) | 2000-03-02 | 2002-08-28 | Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process. |
ZA200206890A ZA200206890B (en) | 2000-03-02 | 2002-08-28 | Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process from a naphtha/steam feed. |
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ZA200206890A ZA200206890B (en) | 2000-03-02 | 2002-08-28 | Process for producing polypropylene from C3 olefins selectively produced in a fluid catalytic cracking process from a naphtha/steam feed. |
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