Elucidation of novel mechanisms to produce value-added chemicals from vapour phase conversion of ferulic acid

Abstract

Ferulic acid is one of high molecular weight phenolic compounds of raw bio-oil produced from thermochemical conversion of lignocellulosic biomass. Due to its unique chemical fragmentation, it can be converted into various specialty chemicals such as methyl-2-phenylacetate, cinnamic acid, methyl-benzoate, methyl- and ethyl-cinnamate and others. In this numerical study, ferulic acid is converted into aforementioned specialty chemicals with analyses of their potential energy surfaces, activation energies, and thermodynamic feasibilities by density functional theory using B3LYP functional. The selection of B3LYP functional is also demonstrated by comparing single point energy of a couple of reaction pathways with those obtained by M05-2X functional. In the thermochemical analyses, all reaction schemes are subjected at a wide range of temperature conditions varying from 598 to 898 K. The productions of phenol and cinnamic acid required overall activation energy of only 5 kcal/mol due to the same rate-determining step. Further conversion of phenol into the end product methyl-benzoate is not advantageous because of high-energy demands and positive values of reaction free energy and reaction enthalpy at each temperature. According to thermochemical analysis, the production of methyl-2-phenylacetate is highly spontaneous even at the lower temperature; however, at elevated temperature conditions, its spontaneity decreases and exothermicity improves further.