Catalytic applications of layered double hydroxides in biomass valorisation

Abstract

Catalytic applications of layered double hydroxides in biomass valorisation.', Current opinion in green and sustainable chemistry., 22 . pp. 29-38.

Alkali-Free Hydrothermally Reconstructed NiAl Layered Double Hydroxides for Catalytic Transesterification

“…(1−x) Al 3+ x (OH) 2 ] x+ (A n− ) x/n •yH 2 O are interesting materials for photo-, electro-, and thermocatalysis [1,2] and electronic applications [3][4][5]. They typically adopt three-dimensional, lamellar structures of mixed metal oxyhydroxide platelets, with the interlayer voids providing nanoporous chemical reactors [6].…”

Catalytic deoxygenation of fatty acidsviaketonization and α-carbon scissions over layered alkali titanate catalysts under N2

“…We also tested the catalytic activity of the mixed Mg/Al oxide which is known 25,[49][50][51][52][53] to catalyze carboxylic acid ketonization by basic sites. Generally, it shows similar catalytic activity (entry 6) to that lepidocrocite titanate catalysts especially K 0.8 Li 0.27 Ti 1.73 O 4 .…”

Perovskite Catalysts for Biomass Valorization

“…6 Waste lignocellulosic biomass, such as nonedible parts of crops (leaves, stalks, husks, and shells), grasses, and the organic component of MSW, is recognized as a major resource (global lignocellulosic biomass production is estimated to be around 146 billion tons per year 7 ) and sustainable raw material to displace fossil resources in the production of chemicals and transportation fuels. 8,5,9,10 Hemicellulose is a biopolymer of pentoses (xylose, ribose, and arabinose) and hexoses (glucose, fructose, mannose, and galactose), being dominated by xylose, a monomer of xylan which is more readily hydrolyzed than cellulose. 8,11 Cellulose is a linear homopolymer composed of glucosyl units bridged by β-1,4-glycosidic bonds 11 and can be hydrolyzed to glucose using enzyme or acid catalysts.…”

“…8,5,9,10 Hemicellulose is a biopolymer of pentoses (xylose, ribose, and arabinose) and hexoses (glucose, fructose, mannose, and galactose), being dominated by xylose, a monomer of xylan which is more readily hydrolyzed than cellulose. 8,11 Cellulose is a linear homopolymer composed of glucosyl units bridged by β-1,4-glycosidic bonds 11 and can be hydrolyzed to glucose using enzyme or acid catalysts. 5 Lignin is a highly aromatic biopolymer containing methoxy and phenolic groups, 12 and while it contains valuable components such as vanillin, it remains challenging to selectively convert to desired products.…”

“…Biomass processing requires lower temperature, often liquid phase, transformations 17 such as hydrolysis, dehydration, isomerization, oxidation, aldol condensation, hydrogenolysis, and hydrogenation, 18−21 many involving acid or base catalysis. 8 Acid-catalyzed dehydration of sugars, e.g., glucose and fructose, allows access to platform chemicals such as 5-hydroxymethylfurfural (5-HMF) in aqueous media, 22 or alkoxymethylfurans (e.g., 5-methoxymethylfurfural, MMF) in alcoholic solvents, 23 which are precursors to plastics, building materials, and fine chemicals or pharmaceuticals. These multistep reactions typically require cooperation between multiple active sites, either integrated into a single bifunctional catalyst or through two or more physically separated catalysts; for example, bifunctional acid−base reactions can be coupled with metal catalyzed hydrogenation or oxidation.…”