Operating conditions to maximize clean liquid fuels yield by oligomerization of 1-butene on HZSM-5 zeolite catalysts

Abstract

Abstract The effect of operating conditions has been extensively studied for the selective oligomerization of 1-butene to clean synthetic liquid fuels. HZSM-5 zeolite (SiO2/Al2O3 ratio = 30–280) based catalysts provided with a hierarchical porous structure have been tested in a fixed bed reactor under the following conditions: 175–325 °C; 1.5–40 bar; space time, 0.5–6 gcatalyst·h molC−1. Special attention has been paid to individual and lumped gaseous and liquid product distribution (which have been characterized by gas chromatography, GC × GC/MS and simulated distillation), as well as to catalyst stability, by performing long duration experiments (20 h). An optimum region to maximize both naphtha (C5-11, >40%), and diesel (C12-20, >20%) yields has been established at 250–275 °C and 30 bar for space time values of 2–4 gcatalyst h molC−1. Furthermore, the catalysts have tended to a pseudo-stationary deactivation state after 5 h on stream, where the coke deposited on the spent catalysts is mainly composed of adsorbed bulky oligomers (determined by TPD-N2), with low coke contents ∼1.0–1.5 wt% (determined by TPO).