Production of 5 - (Halomethyl) Furfurals from Cellulosic Biomass and their Synthetic Upgrading into Renewable Chemicals

Abstract

The transportation fuels and most of the bulk and fine chemicals are primarily sourced from crude oil. However, the excessive use of crude oil has depleted the reserves, created a disparity between the demand and supply, and degraded the environment. In search of a renewable and preferably carbon-neutral source, biomass has found by many as a commercially-feasible replacement for fossilized carbon. The chemocatalytic valorization of biomass is of particular interest since they are fast, biomass agnostic, selective, and can potentially be integrated into the existing infrastructure. A major challenge in the chemocatalytic value addition of biomass is to develop a new generation of robust, selective, inexpensive, and environment-friendly catalysts that can selectively deconstruct the biopolymers. In this regard, the acidcatalyzed depolymerization and dehydration of biomass-derived carbohydrates (e.g., cellulose) into furanics is an elegant way of removing excessive functionalities from the carbohydrate. Biomass-derived 5-(hydroxymethyl)furfural (HMF), 5- (chloromethyl)furfural (CMF), furfural and levulinic acid (LA) have been used as renewable chemical building blocks for further value addition into fuels and specialty chemicals. In this thesis work, an improved synthesis of CMF and LA have been reported using aqueous HCl as the acid catalyst in the presence of quaternary ammonium chloride as a surface-active agent (SAA). The SAA afforded noticeably higher yields of CMF and LA compared to the control reactions. The reactions were optimized on various reaction parameters such as temperature, duration, loading of the substrate, and the loading of SAA. The SAA was successfully recovered and recycled. LA was converted into alkyl levulinates, a potential diesel additive and a renewable solvent, in the presence of phosphotungstic acid as an environment-friendly and recyclable catalyst. Alkyl levulinates were also prepared by the alcoholysis of CMF and furfuryl alcohol using HClO4-SiO2 as an inexpensive heterogeneous catalyst. A scalable and high-yielding preparation of 5-(alkoxymethyl)furfural, a novel fuel oxygenate, from CMF has also been reported.