Nickel supported aluminosilicates as catalysts

Propylene and other olefins of higher molecular weight can be easily oligomerized over a wide range of zeolitic and nonzeolitic acid catalysts.[1114] However, in the case of ethylene only low conversions can be obtained over acidic catalysts. Transition metal catalysts, on the other hand, and particularly those based on Ni 

Miller[72] has described a process for the production of hydrocarbons in the lube base stock range. The process involves the use of a Ni-ZSM5 zeolite as catalyst for dimerization of C5-C11 olefins into a first product containing C10-C22 olefins. This first product is subjected to an additional dimerization step, using the same or similar catalyst giving a second product that includes hydrocarbons in the lube base stock range. 

Ethylene oligomerization over Ni and Pd zeolites has been reported by Lapidus and Krylova.[73] It was found that NiCaX exhibited high selectivity for ethylene dimerization at 508 K. The highest activity and selectivity were achieved with a sample with a Ni content of 2.5 wt%, trara.v-2-butcnc being the major product. PdCaX also shows excellent selectivity to trans-2-butene, giving 65 % selectivity for a total yield of the C4 fraction of 78 %. 

Sakaguchi et a/.[80] have reported that combined use of Ni-silica alumina and BPO4 is more effective promoting the oligomerization of ethylene than Ni silica alumina alone. An increased Q, fraction and an equilibrium mixture of n-butene was formed as C4 products using the catalyst combination, whereas on Ni-silica alumina alone 1-butene was mainly obtained. 

Recently, Angelescu et a/.[92] have studied the activity and selectivity for dimerization of ethylene of various catalysts based on Ni(4,4-bipyridine)Cl2 complex coactivated with A1C1(C2H5)2 and supported on different molecular sieves such as zeolites (Y, L, Mordenite), mesoporous MCM-41 and on amorphous silica alumina. They found that this type of catalyst is active and selective for ethylene dimerization to n-butenes under mild reaction conditions (298 K and 12 atm). The complex supported on zeolites and MCM-41 favours the formation of higher amounts of n-butenes than the complex supported on silica alumina, which is more favourable for the formation of oligomers. It was also found that the concentration in 1-butene and cw-2-butene in the n-butene fraction obtained with the complex supported on zeolites and MCM-41, is higher compared with the corresponding values at thermodynamic equilibrium. 

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