Mechanistic Kinetic Model Development of Catalytic Pentose Model Compounds Dehydration to Furfural: Quantitative Structure-Activity Relationships of Monosaccharides, Catalysts, and Solvents

Abstract

Separated platform chemicals, such as furfural (F), can be produced by the conversion of lignocellulosic waste biomass. Heterogeneous catalytic dehydration of carbohydrate pentose sugars is a simple way to remove excess oxygen. The long-term goal is the replacement of established homogeneous catalytic processes. This study investigates the influence of catalytic activity, process conditions, and different solvents using a kinetic model and robust statistical analysis. Four different catalysts, including pure and doped H-beta zeolite with Nb, Sn, and Zr, were compared. Catalyst acidity impacts the kinetics of the process but has a limited impact on selectivity. Feedstocks-arabinose/ribose, were assessed in addition to xylose, showing similar reaction rates and selectivity. The solvent analysis included water, methanol, ethanol, isopropanol, or dimethyl sulfoxide (DMSO). The results demonstrate that both solvent and temperature significantly influence the reaction kinetics and selectivity, with the solvent exerting the strongest effect on furfural yield and product distribution. The highest synthesis selectivity toward F was 60 mol % at 180 °C in DMSO. The work identifies the solvent as the crucial parameter for determining the selectivity and kinetics of the process through experimental results and detailed kinetic analysis, which included rate constant values for F-forming reaction sets, quantitative activity relationships, and phenomenological empirical correlation for determining numerical quantities, based on composition and acidity.