Gasoline production by oligomerization of 1-butene at low pressure: Kinetic model and reactor simulation

Abstract

A five lump kinetic model (C4=, C8=, C12=, C1-C4 and C5-C12) has been established for 1-butene (C4=) oligomerization at low pressure (1.5 bar) and 275 °C on an HZSM-5 zeolite catalyst agglomerated in a γ-Al2O3 mesoporous matrix. The kinetic parameters have been calculated based on the results obtained in a packed-bed reactor for different concentrations of 1-butene in the feed (with N2 as diluent) and different values of space time (0.5–9.5 gcatalyst h molC-1). The model quantifies the evolution with time on stream of the concentrations of the lumps, considering the selective deactivation of the catalyst for the oligomerization, cracking and pool of secondary reactions. Furthermore, it allows to calculate the remnant activity of the catalyst in the pseudo-steady state (>5h on stream) for the different reaction groups, as well as the corresponding product distribution. The kinetic model has been used in the simulation of the packed-bed reactor to study the effect of space time and 1-butene partial pressure variables. At the conditions range studied experimentally, 39.4 % gasoline yield (C5-C12 fraction, mainly composed of olefins) and a 1-butene conversion of 45 % are achieved in the pseudo-steady state of the catalyst, at a space time of 9.5 gcatalyst h molC-1 and a partial pressure of 1-butene of 0.8 bar. Additionally, for values exceeding those studied experimentally, the model predicts at the pseudo-steady state a gasoline yield of 60 % at a space time of 30 gcatalyst h molC-1 and a partial pressure of 1-butene of ∼ 0.5 bar.