High-Entropy Materials as the Catalysts for Valorization of Biomass and Biomass-Derived Platform Compounds

Abstract

Relying on the excellent properties of high-entropy materials (HEMs), the high-entropy alloys (HEAs) and high-entropy oxides (HEOs) are considered as the novel heterogeneous catalysts for the valorization of biomass feedstock and biomass-derived platform compounds. HEAs and HEOs are opening up a vast, unknown field of alloy or oxide composition and can realize the catalyst stability with the rocksalt crystal structure by means of configurational entropy. In this paper, the general component and structure of lignocellulosic biomass are concisely introduced. Then, the fundamental character of HEMs including the inherent merit and regulatable property as promising catalytic materials is discussed. Therein, the inherent merits of HEMs are defined as the high entropy effect in thermodynamics, lattice distortion in the structure, sluggish diffusion in dynamics, and the cocktail effect in performance; correspondingly, the regulatable property contains the surface area, the applicability of the element, and the size of nanoparticles. In addition, the valorization of biomass feedstocks including the direct pyrolysis of biomass, the selective transformation of cellulose and hemicelluloses, the utilization of lignin, and the catalytic valorization of furfural (FUR) and 5-hydroxymethylfurfural (5-HMF) as the representative biomass-based platform compounds is discussed, and the obtained valuable reaction products are briefly summarized. Finally, further research orientations for the selective volarization of biomass by the use of HEMs as heterogeneous catalysts is prospected, and the recommendable HEAs and HEOs catalysts including the potential metallic elements are proposed for the biomass pyrolysis, the conversion of (hemi)­cellulose, and the transformation of lignin, respectively.

Selectivity-controllable hydrogen transfer reduction of α,β-unsaturated aldehydes over high-entropy catalysts

“…The crystal structure of high-entropy oxides has a random distribution of each element close to the equimolar ratio, and the formation of oxygen holes and defect sites due to lattice distortion contributes to the improvement of catalytic activity. 25–27 Recently, MgLaFeMnCu high-entropy oxides showed good catalytic performance and successfully realized the oxidative condensation reaction of furfural with C 2 –C 12 fatty alcohols. 28 However, the use of high-entropy catalysts in the selective reduction of unsaturated carbonyl compounds still remains a challenge at present.…”

Selective aerobic oxidative C–C bond cleavage using a high-entropy oxide-derived multimetallic catalyst

“…Nowadays, the catalytic application of HEOs in the biomass transformation and the oxidative C–C bond cleavage has been considered as a promising research orientation in the chemical field. 20,21 Herein, a new HEO-derived multimetallic catalyst, including Cu, Fe, Co, Mn, and Mg, is prepared to promote the aerobic oxidative C–C bond cleavage of 1,2-diols and lignin models. The results show that a 96.1% conversion with 96.2% selectivity of benzaldehyde is achieved in the transformation of 1-phenyl-1,2-ethanediol under mild conditions.…”