Catalytic Oligomerization of Ethylene: Experimental Insight into the Effect of Supercritical Reaction Conditions

Ethylene oligomerization is a valuable chemical process for the production of carbon backbones for a variety of commodity chemicals ranging from fuels to surfactants and lubricants. Traditionally, this reaction has been covered extensively in homogeneous catalysis. The development of a heterogeneous catalytic process, however, is of significant academic and industrial relevance as it abides by green chemistry principles and is more easily scalable. However, coke deposition is a major issue for most heterogeneous systems. It has been determined previously that supercritical fluids have a unique ability to solvate coke. In this talk, we will explore the effect of supercritical reaction conditions on ethylene oligomerization. Ni-Hb catalysts were synthesized in the laboratory via a dropwise impregnation technique and used in a single-pass, high pressure packed bed flow reactor. Below its critical point, ethylene was a reactant for oligomerization reactions into C4-C12 olefins. As the partial pressure of ethylene exceeded its critical pressure, ethylene gas was observed to participate both as a reactant and as a solvent. This solvation effect was most evident as the amount of carbon deposition observed on the catalysts at supercritical conditions was found to be considerably lower than that of non-supercritical conditions.