Design of Bifunctional Nanocatalysts for Biomass Processing

Abstract

Bifunctional catalysts consisting of mono- or bimetallic nanoparticles (NPs) and zeolite supports received considerable attention due to excellent catalytic properties in numerous reactions including direct and indirect biomass processing. Here, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods allowing the best interplay (synergy) between metal and acid sites which is normally achieved for small NPs well-distributed through zeolite. We focus on modification of zeolites to provide structural integrity and controlled acidity which can be accomplished by incorporation of certain metal ions or elements. The other modification avenue is the adjustment of the zeolite morphology including creation of numerous defects for the NP entrapment and designed porosity. In this review we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations many assumptions about interactions between active sites stay unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years.