Kinetic Modelling for Deactivation by Coke Deposition of a HZSM-5 Zeolite Catalyst in the Transformation of Aqueous Ethanol into Hydrocarbons

Catalyst Deactivation by Coke in the Transformation of Aqueous Ethanol into Hydrocarbons. Kinetic Modeling and Acidity Deterioration of the Catalyst

“…The procedure is described in detail in previous papers for the MTG process 22,46 and for this process. 45 The best-fit deactivation kinetic model (among the different cases of the general expression in eq 14) is This kinetic model considers ethene, the olefin lump (propene and butenes), and the gasoline lump as coke formation precursors. This hypothesis is well supported by the oligomerization capacity of light olefins to produce compounds that will remain trapped in the porous structure 47,48 and by the cyclization and condensation capacity of aromatic compounds (at high ratios in the gasoline lump).…”

“…In previous papers, the validity of the kinetic model has clearly been shown for the entire range of operating conditions studied. 44,45 Nevertheless, at extreme conditions of high concentrations of either a coke precursor (ethene) or the other coke precursors as a whole (olefins and gasoline), the following points should be taken into account concerning the use of alternative models to eq 17: First, for temperatures below 400°C (when cracking of gasoline is not significant) and high space time and, in general, under conditions in which the concentrations of the olefin and gasoline lumps are high, a better fitting to the experimental data is obtained when similar values of the constants k dOG and k dE are used in eq 17, which shows that ethene and olefin/gasoline lump contribute to coke formation to the same degree. This result corresponds to a deactivation that takes place in series-parallel with the main reaction.…”

Modeling of Catalyst Deactivation in Bioethanol Dehydration Reactor

“…In addition, some authors believe that olefins are also precursors of coke formation, as presented in Gayubo et al 7 Therefore, it was considered that the deactivation mechanism involving the precursors ethanol and olefins may occur in parallel, which is represented mathematically by the sum of two distinct contributions involving the concentration of each of these precursors.…”

In situ fast pyrolysis of biomass with zeolite catalysts for bioaromatics/gasoline production: A review

“…The presence of water initiated a competitive interaction with the lighter alcohols for the active acid sites of H-ZSM-5. This limits the oligomerization and condensation of olefins such as propylene into coke precursors (i.e., polyaromatics) [88][89][90][91]. At reaction temperatures above 400°C, the polyaromatics that were generated became trapped inside the catalyst channels and caused serious deactivation.…”