Guaiacol, a model lignin compound, conversion to catechol over SBA-15 and ZSM-5 catalyst in a fixed bed reactor

Abstract

Biomass conversion to value added chemicals to be used as industrial platform molecules for further synthesis of commodity chemicals has opened new window for scientists. Biomass is a lignocellulosic compound and it requires technological development since biomass is a complex molecule of linear, cyclic and aromatic hydrocarbons. Lignin being aromatic in nature can beneficial for the production of phenolic hydrocarbons. In this work conversion of Guaiacol, a model lignin compound to different aromatic hydrocarbon is performed over pure silica and alumina silica catalysts e.g. SBA-15and ZSM-5 in a fixed bed catalytic reactor. SBA-15 material was synthesized at different aging time leading to improvement in surface area and pore diameter whereas ZSM-5 was pre-treated with H₃PO₄ and KOH to modify their acidic strength. Maximum Guaiacol conversion in absence of catalyst was obtained aa 90.1 % at 550oC, 97.33 % at 550 °c in presence of SBA-15 (C) and 95.33 % in presence of P/ZSM-5, indicating the catalyst helps in enhancing the conversion, however depends on the type of catalysts and its properties like surface area, pore diameter and Lews/Bronsted acid strength. Similarly the selectivity of catechol was observed to be maximum with SBA-15 (C) as compared to other catalyst owing to its high surface area and large pore diameter. The GCMS analysis of the liquid product obtained includes Dimethyl phenol, 2-dimethoxy benzene, 2-ethyl,5-methyl phenol, catechol, Ethynylanisole and O-cresol