Lewis acid catalysts, where electron lone pairs from heteroatoms (e.g., N, O, Cl) interact with coordinatively unsaturated, cation active sites to form coordinate covalent bonds, are widely known in homogeneous catalysis and biochemistry. At low reaction temperatures, Lewis acids do not typically react with olefins or C-H sigma bonds. However, at higher temperatures applicable to heterogeneous catalysts, hydrocarbon reactions involving Lewis acid site can occur.
Highly loaded Ga3+ Lewis acid sites on SiO2 and Al2O3 supports were synthesized to explore differences in the structure of the catalytic site and effect of the support type on olefin oligomerization. The structures and types of acid sites were characterized using X-ray absorption spectroscopy and pyridine infrared spectroscopy, respectively. Additionally, the catalytic performance, including reaction rates and product selectivity, was evaluated for olefin oligomerization of ethylene and propylene. For this reaction, hydrogen transfer, double-bond isomerization, and the formation of non-oligomers products were also observed. The reaction pathway and elementary reactions will also be presented.
