Title of Invention

"A PROCESS FOR PRODUCING OLIGOMERS FROM ALPHA OLEFINS"

Abstract

A process for producing oligomers from alpha-olefins using a catalyst comprising hexagonal mesoporous silica having sulphated metal oxide of metal selected from the group of zirconium, titanium, iron, aluminium, tin and bismuth incorporated therein and having a surface area in the range 200-500 m2/g; a pore volume in the range of 0.1 - 0.3 cm3/g; a pore diameter in the range of 25-35 °A and XRD peak at 2 theta angle being 0-3, the process comprising; i. containing alpha olefin feedstock, RCH=CH2 wherein R represents as alkyl radical having 6 to 12 carbon numbers with said catalyst; ii. adding 1 to 10% by weight of alpha olefin, under agitation; iii. raising the temperature to 120 to 220 °C, in autoclave, appropriate to the hydrocarbon(s) in the feedstock and maintaining the reaction at the temperature under agitations for a period between 2 to 10 hours under pressure; iv. cooling the autoclave to room temperature and separating the solid catalyst from the liquid products of the reaction followed by separating the unreacted monomer and the oligomer

Full Text

This invention relates to a process for oligomerization of alpha olefins using solid catalysts. This invention particularly relates to the process for oligomerizing straight chain alpha olefins with carbon number 8-14 using sulfated metal oxide mesoporous molecular sieve as catalyst. Another facet of this invention relates to the process for manufacturing synthetic lubricant from alphaolefins. Alpha olefins of different carbon numbers are polymerised for prepakig lubricants. However, 1-decene is by and far largely used as it has applications over the widest range of temperature. 1. Homogeneous catalyst: Oligomerization of alpha olefin is a catalytic process, and depending upon the catalyst used, synthetic lubricant of different viscosity grades can be prepared. Currently BF3- alcohol catalytic system is used to oligomerize 1-decene for preparation of lubricants of low molecular weights (dimer, trimer, tetramer etc.) which have viscosity in the range of 2-10 cSt, and A1C13 catalysts (at 80-100°C) for the preparation of those of high molecular weights having viscosity in the range 40-100 cSt. Different poh/alphaolefins (PAOs) are formed by oligomerization of 1-decene in these processes. The distribution of oligomers formed in reaction with these catalysts and other two catalyst systems such as triethyl aluminium-titanium tetrachloride and ditertiarybutyl peroxide are shown in the Table-1. The products of these reaction are separated by distillation and different fractions are used for formation of synthetic lubricants for appropriate application. Table-1 Oligomerization of 1-decene with homogeneous catalysts (Table Removed) Operation with all homogeneous catalysts is cumbersome and the waste disposal is an ecological problem 2. Heterogeneous/solid catalysts: i). A recent Indian Patent No. 179465 (to Mobil Oil Corp) employs chromium catalyst on a porous support for oligomerization of C2 to C5 alpha olefin. ii). Another Indian Patent No. 179295 (to Hoechst) employs magnesium alcoholate reacted with a transition metal compound for preparing polyalpha olefins of C3 - C12 carbon atoms. iii). In a patent issued to Montel North America, Inc (Indian Pat.No. 179447) titanium compounds supported on magnesium halides in active form are used for polymerization of Ct toC6 alpha olefins. iv). Reduced chromium on a silica support used as a catalyst for oligomerization of C6 to C20 alpha olefins is reported in US patent No. 4, 827 064 and 4, 827 073. v). Some US patents report the use of heterogeneous mesoporous zeolite catalysts for oligomerization of alpha olefins, mainly for propylene oligomerization. Some of these are given in Table-2 and selectivity of propylene oligomers obtained by these processes are given in Table-3. Table-2 Oligomerization of propylene using heterogeneous catalysts (Table Removed) (WHSV = Weight hourly space velocity, hr”1) Table-3 Percent propylene oligomers in the product (Table Removed) These processes start with alpha olefin of various carbon numbers, particularly 2 and 3 which give a mixture of oligomers which again have to be separated by distillation. In a patent issued to Montel North America, Inc (Indian Pat.No. 179447) titanium compounds supported on magnesium halides in active form are used for the polymerization of C1 to C6 alpha olefins. Reduced chromium on a silica support used as catalyst for oligomerization of C6 to C20 alpha olefins is reported in US patent No. 4, 827 064 and 4, 827 073. There has been increasing interest in the use of 2 cSt poh/alphaolefin in certain defense applications such as low temperature hydraulic fluid and dielectric coolant for radar and missile systems. Earlier Silicate-ester based fluids were used for such equipment. Silicate esters being hygroscopic in nature easily decompose in the presence of water to form flammable alcohols which reduce the flash point of the fluid and hence there is a failure of equipment. After testing a variety of alternative fluids, it has been found that 2 cSt hydrogenated PAO (hydrogenated dimer of 1-decene) meets all the established specifications to replace silicate- ester based fluid. Since hydrogenated PAO is a saturated hydrocarbon and hydrophobic in nature, it is relatively inert and remains unchanged in the presence of water. The current trend is to replace silicate esters employed as aircraft-equipment dielectric-coolants by 2 cSt hydrogenated PAO. It would also be useful in automobile industry. It is thus the basic objective of the present invention to provide a process for oligomerization of alpha olefins with carbon numbers C6-C16 to obtain an oligomer with two monomer units or molecule as the major product so that the problem of separation by distillation from higher oligomers can be eliminated. Another object of this invention is to provide for pure dimmers by using pure monomers. After trying out different catalysts we have found that using UDCaT-1, a sulfated metal oxide molecular sieve as described in our co-pending. Indian Patent Application No. 3595/DEL/97 entitled "A process for preparation of a highly acidic mesoporous solid catalyst UDCaT-1 for acid catalysed reactions" as a catalyst controls oligomerization of alpha olefin upto two units stage. Thus according to the present invention there is provided a process for producing oligomers from alpha-olefins using a catalyst comprising hexagonal mesoporous silica having sulphated metal oxide of metal selected from the group of zirconium, titanium, iron, aluminium, tin and bismuth incorporated therein and having a surface area in the range 200-500 m2/g; a pore volume in the range of 0.1 - 0.3 cm3/q; a pore diameter in the range of 25-35 °A and XRD peak at 2 theta angle being 0-3, the process comprising; i. containing alpha olefin feedstock, RCH=CH2 wherein R represents as alkyl radical having 6 to 12 carbon numbers with said catalyst; ii. adding 1 to 10% by weight of alpha olefin, under agitation; iii. raising the temperature to 120 to 220 °C, in autoclave, appropriate to the hydrocarbon(s) in the feedstock and maintaining the reaction at the temperature under agitations for a period between 2 to 10 hours under pressure; iv. cooling the autoclave to room temperature and separating the solid catalyst from the liquid products of the reaction followed by separating the unreacted monomer and the oligomer. In the above process of the invention the catalyst used is UDCaT-1, a salfated metal oxide molecular sieve as discribed in the co-pending Indian Patent Application No. entitled "A process for preparation of a highly acidic mesoporous solid catalyst". In particular, the said catalyst comprised synergistic combination of sulfated metal oxide and mesoporous zeotypes having surface area in the range of 200-S00 m2/g; pore volume in the range of 0.1-0.3 m3/g; pore diameter in the range of 25-3 5°A. The above synergistic solid catalyst comprising the said sulfated metal oxide and mesoporous zeotypes further comprising: Si in an amount of 50-60% by wt. ; S in an amount of 5-10% by wt.; and Zr in an amount of 40-50% by wt.; The invention will now be illustrated with the help of Examples. The Examples are by way of illustration only and in no way restrict the scope of the invention. Example 1: Process for dimerization of 1-decene Materials: 1-decene was obtained from Albemarle Corp., USA. Catalyst UDCat-1 prepared by Yadav and Krishnan is described in our co-pending Indian Patent, Application No. Apparatus: Parr autoclave All experiments were carried out in 100 ml stainless steel Parr autoclave. A pitched four bladed turbine impeller was used for agitation. Process: 36 gm of 1-decene, 2.5 gm UDCaT-1 catalyst were charged into autoclave and the temperature was raised to desired 190°C and speed of agitation was maintained at 800 rpm under autogeneous pressure for 4 hrs. The autoclave was cooled to room temperature and then the catalyst was separated by filtration by using a Buchner funnel. The catalyst was washed with acetone and calcined at 650°C for 3 hrs and preserved for reuse. Filtrate showed only two peaks viz, monomer and dimer on GLC as per detail given in chart-1. The monomer was separated by distillation at 130°C under vacuum (200 mm of Hg) and weighed 18 gm. This was preserved for reuse. The second fraction distilled out at 160°C under vacuum (200 mm of Hg) was of dimer and weighed 18 gm. There were no polymers left in the still. Analysis of the dimer fraction. Dimer was analysed by GC and its molecular weight was confirmed by GC-MS and both analysis show that dimer fraction is 100% pure dimer. Chart-1 Details of GLC. Analysis of the sample was done by using a gas chromatograph (Perkin-Elmer 8500) with a flame ionisation detector. The products were analysed for 1-decene, dimer and trimer. Column : Stainless steel Stationary phase : 10% OV 17 supported on chromosorb WHP Dimensions : 2 Mt. length x 0.003m dia Conditions: Carrier gas : nitrogen Carrier flow rate : 30ml/min Injector : 300°C Detector: 300°C Oven temperature conditions: Temperature 1 :150°C /1 min Ramp 1 :30°C/min Temperature 2 :300°C/10min Example 2 Hydrogenation: The dimer fraction obtained in the Example 1 was hydrogenated over nickel catalyst at 150°C to give hydrogenated lubricant product. The viscosity of hydrogenated 1-decene dimer as shown in Table-4. It was found to be acceptable /comparable to other commercial product. Table-4 Viscosity of hydrogenated 1-decene dimers Viscosity in centistokes(cSt) (Table Removed) * (DURASYN 162, Albemarle Corp, USA). + method used ASTM D KV 445 Pour point and viscosity index were measured (ASTM D 2270, 1298 ) and it were found to be -60°C and 99 respectively compared to -65°C and 97 of the authentic dimer (DURASYN 162, Albemarle Corp, USA). Examples 3-7 In these Examples the procedure of Example 1 was repeated replacing the UDCaT-l catalyst by other solid acid catalysts as shown in Table-5. Product distribution of the different oligomers found by GC on 10% OV17 on chromosorb WHB are given in Table-5, for comparison results of Example-1 are also included. Table-5 (Table Removed) DTP: Dodecatungstophosphoric acid The catalysts used in the Example 1 and 3 were prepared as described in our copending Indian Pat. Application entitled and that of Example 4 and 5 were prepared by conventional method in. Where as DTP and K10 were obtained from a reputed firm. As can be seen from the Table-5 that HMS is not at all effective under these conditions and all the other catalysts used give the mixture of oligomers. In the presence of K10 montmorrillonite catalyst selectivity towards dimer formation is higher at 88. UDCat-1 catalyst alone gives 100% selectivity towards dimer formation, thereby making it easy to recycle the unreacted monomer (50%). Examples 8 and 9 In these examples other olefins like 1-octene and 1-dodecene were also oligomenzed as per the procedure given in Example-1 and the results obtained are shown in Table-6. Table-6 Oligomerization of 1-octene and 1-dodecene using UDCaT-1 catalyst (Table Removed) Example 10 In this example mixture of two pure monomers viz. olefin 1-octene and 1-decene (50:50 % by wt/wt) were oligomerised as per the procedure given in Example 1 and the results obtained are given in Table - 7 Table - 7 Oligomerization of mixture of 1-octene and 1-decene using USCaT-1 catalyst (Table Removed) It was found that there was no trimer of 1-octene or 1-decene formed. Absence octadecene(Cig) in the reaction product showed that there was no reaction between 1-octene and 1-decene. These examples show that the process of oligomerization of the present invention controls oligomerization to the dimer stage. Further, the monomer could be distilled out and reused. In a continuous process, monomer could be recycled. Catalyst can be regenerated and used again and again. WE CLAIM : 1. A process for producing oligomers from alpha-olefins using a catalyst comprising hexagonal mesoporous silica having sulphated metal oxide of metal selected from the group of zirconium, titanium, iron, aluminium, tin and bismuth incorporated therein and having a surface area in the range 200-500 m2/g; a pore volume in the range of 0.1 - 0.3 cm3/g; a pore diameter in the range of 25-35 °A and XRD peak at 2 theta angle being 0-3, the process comprising; i. containing alpha olefin feedstock, RCH=CH2 wherein R represents as alkyl radical having 6 to 12 carbon numbers with said catalyst; ii. adding 1 to 10% by weight of alpha olefin, under agitation; iii. raising the temperature to 120 to 220 °C, in autoclave, appropriate to the hydrocarbon(s) in the feedstock and maintaining the reaction at the temperature under agitations for a period between 2 to 10 hours under pressure; iv. cooling the autoclave to room temperature and separating the solid catalyst from the liquid products of the reaction followed by separating the unreacted monomer and the oligomer 2. A process as claimed in claim 1, wherein said unreacted monomer and the oligomer are separated by distillation under vacuum. 3. A process as claimed in claim 1, wherein said alpha olefin feed stock and said sulphated metal oxide incorporated hexagonal mesoporous silica is contacted in an autoclave. 4. A process as claimed in claim 1, wherein the oligomerisation reaction is controlled to a dimer stage. 5. A process for producing oligomers from alpha-olefins substantially as herein described and illustrated with reference to the accompanying examples.

Documents:

3590-del-1997-abstract.pdf

3590-del-1997-claims.pdf

3590-del-1997-complete specification (granted).pdf

3590-del-1997-correspondence-others.pdf

3590-del-1997-correspondence-po.pdf

3590-del-1997-description (complete).pdf

3590-del-1997-description (provisional).pdf

3590-del-1997-form-1.pdf

3590-del-1997-form-19.pdf

3590-DEL-1997-Form-2.pdf

3590-DEL-1997-Form-3.pdf

3590-del-1997-form-4.pdf

3590-del-1997-form-6.pdf

3590-del-1997-gpa.pdf

3590-del-1997-petition-137.pdf