Utilization of zeolite catalysts in biomass exploitation: a minireview

Abstract

This minireview discusses the use of zeolites as catalysts in all stages of lignocellulose biomass (LCB) valorization process. A summary of some synthesis and characterization methods for zeolitic materials is provided. Utilization of various active sites of zeolites is explored with the focus on Brønsted and Lewis acid sites and the importance of hierarchical structures in the processes involving bulky biobased molecules. Zeolites modified by top-down methods, specifically desilication with various basic reagents, are good candidates for applications in LCB valorization. Some novelty methods such as a dry milling for incorporating metal nanoparticles into zeolite structure are mentioned. An overview of studies utilizing zeolites in processes such as catalytic pyrolysis of LCB, acid-catalyzed hydrolysis and reactions of platform molecules (ethanol, furans, glycerol, bio-hydrocarbons, lactic acid, succinic acid, levulinic acid, sorbitol, xylitol) is discussed. Special attention is dedicated to reactions of biomass-derived alcohols and value-added chemicals produced from them, e.g., esters. The most successful industrial zeolite application—fluid catalytic cracking—is also summarized for comparison. Challenges of zeolite stability in reactions carried out in liquid water conditions, as well as possibilities of catalyst stabilization, e.g., with extra-framework aluminum, or hydrophobization of the surface, are explored. Graphical abstract: [Figure not available: see fulltext.]