Oligomerization of propylene with silica-alumina and nickel oxide-silica-alumina (Ni content: 13wt%) catalysts was studied under the high pressure (25-50kg/cm²) continuous flow system. The reaction temperature was varied in the range of 80-350°C and the space velocity 5, 000-10, 000ml-N. T. P. feed/ml-catalyst/hr. From the experimental results obtained, the following conclusions may be drawn.
1) In the presence of the nickel oxide-silica-alumina catalyst, propylene could be polymerized under mild reaction temperature (around 80°C). In this case, dimerization of propylene predominated and the hexene thus produced contained only negligible amount of 3-methyl pentenes.
2) While, in the presence of the silica-alumina catalyst, higher temperatures than 200°C were required for propylene polymerization. In this case, dimerization of propylene was a minor reaction among the polymerization reactions, and the dimerization product hexene contained considerable quantities of 3-methyl pentenes.
3) As to the formation of 3-methyl pentene from propylene, Uchida et al. proposed a mechanism, in which 3-methyl pentene was formed by the decomposition of the cyclobutane ring produced by the combination of two propylene molecules adsorbed on the active center of nickel oxide-silica-alumina catalyst. However, judging from our experimental results, the formation of 3-methyl pentenes was not a special feature of nickel oxide-silica-alumina catalyst. High temperature seemed to favor the formation of 3-methyl pentenes, since a considerable quantity of 3-methyl pentene was obtained under high reaction temperatures, even in the presence of the silica-alumina catalyst.

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Transalkylation of toluene with each isomer of trimethylbenzenes on synthetic mordenites and Y type faujasites was studied. Under the optimum reaction conditions, xylene was formed at the yield of about 45mol% by transalkylation of toluene with 1, 3, 5-trimethylbenzene on H-mordenite, CeY and HY catalyst, accompanied with small quantities of disproportionation of each reactant. With the exception of Be having an ionic radius of only 0.3Å, multi-valent cation-exchanged mordenites showed no activity for this transalkylation. By the infrared spectra method, it was found that ammonia, which had a very small molecular size, interacted with the acid sites of cation-exchanged mordenites, but, pyridine, which had the same molecular radius as alkylbenzenes, could not interact with these sites. These results suggested that the exchanged cation stuck out of the mordenite channel wall, thus hindering the diffusion of reactants into the channel and to the active sites. Trimethylbenzene isomers were reactive in the order of 1, 2, 4->1, 2, 3->1, 3, 5- on the H-mordenite catalyst. This order had a relationship with the molecular shape of trimethylbenzene isomers.

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Transalkylation of toluene with m-ethyltoluene on synthetic H-mordenite and HY faujasite catalysts was studied. Ethyltoluene was much more reactive than toluene in the transalkylation, and was consumed simultaneously by disproportionation of itself. At a low reaction temperature, HY zeolite showed the lower catalytic activity than H-mordenite in this transalkylation. It was found that on the HY catalyst, main initial products of this transalkylation were 1, 3, 5-trialkylbenzenes which were the most thermodynamically stable in the isomers of trialkylbenzene, while, on the H-mordenite catalyst, main initial products were 1, 2, 4-trialkylbenzenes which had a smaller molecular size than 1, 3, 5-trialkylbenzenes. The same phenomena were observed in transalkylation of ethylbenzene with xylene on HY or H-mordenite catalyst. Moreover, in this transalkylation, m-xylene was less reactive than o-xylene on H-mordenite, while, on the HY catalyst, there was no difference between m-xylene and o-xylene in the reactivity of transalkylation. These results suggested that the production of 1, 3, 5-trialkylbenzenes was restrained by the geometric effect between the molecular shape of 1, 3, 5-trialkylbenzenes and the narrow channel of H-mordenite. It was concluded that in the first stage of the reaction on the H-mordenite catalyst, m-ethyltoluene converted to o-ethyltoluene by isomerization and o-ethyltoluene preferentially produced 1, 2, 4-trialkylbenzenes by transalkylation with toluene.

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