Mechanisms, reaction micro-kinetics and modelling of hydrocracking of aromatic biomass tar model compounds into benzene, toluene and xylenes (BTX) over H-ZSM-5 catalyst

Abstract

Biomass tar chemical model compounds (tetralin, naphthalene and 1-methylnaphthalene) have been previously extensively investigated over alumina, various zeolite materials and metal(s)-modified rate catalysts. In this mechanistic work, the relationship between cascade molecular structures, intermediates and reactivity was examined as a first time quantification through detailed micro-kinetic modelling. Herein, systematic measurement-based kinetics, consisting of the 17 gas phase species, 23 bonded adsorbed molecules and sites with the 41 reactions between them, are reported. System was tested based on the obtained experimental data for 1,2,3,4-tetrahydronaphthalene, aromatics and isomer hydrocracking, hydrogenation, and isomerization processes. Proposed derived representation exhibited a good consistent agreement with statistical numerical variation only, including hydrogen-activated hydrocarbon conversion, BTX (benzene, toluene and xylenes) selectivity and coking. Experiments have been before carried out in a packed bed reactor over the H-beta, H-mordenite, H-USY, H-Y and H-ZSM-5, or (Ga, Nb, Ni, NiMo, Sn, W, Zr or H3[P(W3O10)4])/ZSM-5 without the sulphide standard procedures in the functional temperature range of 370–500 °C under applied atmospheric pressure. The most promising yield was achieved over H-ZSM-5. Plug flow reactor (PFR), ideal continuous stirred tank (CSTR) vessel, and coupling the PFR with diffusion was considered, where the 1st one is found as the most fitting to results. The influence of the feedstock on catalytic activity performance was also studied. Deactivation was detected due to stable coke formation, stability was decreased, but predictability was shown. A technique sensitivity analysis was also performed BTX products. Simulations indicated that heat or mass transfer resistances, either intra- or inter-particle, were negligible.