Low-temperature oligomerization of 1-butene with H-ferrierite

Abstract

The effect of temperature, pressure, and solvent on 1-butene oligomerization was studied over H-ferrierite. Two-dimensional GC (GC×GC–MS) was used to analyze the olefin, paraffin, aromatic, and cycloalkane products of the C4 olefin conversion. The reaction product mixture revealed H-ferrierite promoted double bond isomerization, skeletal isomerization, oligomerization, hydrogen transfer, cyclization and cracking reactions. The double bond isomerization reaction reached equilibrium for both C4 and C8 olefins. Primary products from C4 olefin dimerization were 3,4-dimethyl-2-hexene and 3-methyl-2-heptene. The oligomerization products followed the Schulz–Flory chain growth distribution. The chain growth distribution is a function of the C4 olefin conversion. Most of the heavier olefins (>C12) were highly branched (>trimethyl- and methyl-ethyl-species). The selectivity towards oligomerization products was maximized at low temperatures (below 473K). At temperatures above 473K olefins underwent cracking and hydride transfer reactions to produce olefins, paraffins, and aromatics. Co-feeding hexane solvent increased C4 olefin conversion and led to a shift of product distribution from heavier to lighter species. The medium pores were relatively stable for production of longer chain olefins (C6–C20) from C4 olefins near supercritical conditions. The reaction rate was second order in the near-critical region. The deactivation rate decreased with increasing 1-butene partial pressure.