H₂‐Free Selective Dehydroxymethylation of Primary Alcohols over Palladium Nanoparticle Catalysts

Abstract

The dehydroxymethylation of primary alcohols is a promising strategy to transform biomass‐derived oxygenates into hydrocarbon fuels. In this study, a novel, highly efficient, and reusable heterogeneous catalyst system was established for the H2‐free dehydroxymethylation of primary alcohol using cerium oxide‐supported palladium nanoparticles (Pd/CeO2). A wide range of aliphatic and aromatic alcohols including biomass‐derived alcohols were converted into the corresponding one‐carbon shorter hydrocarbons in high yields in the absence of any additives, accompanied by the production of H2 and CO. Pd/CeO2 was easily recovered from the reaction mixture and reused, retaining its high activity, thus, providing a simple and sustainable methodology to produce hydrocarbon fuels from biomass‐derived oxygenates.

Reductive Catalytic Fractionation of Wheat Straw Biomass

“…Methyl esters of ferulic/coumaric acid were reported to be produced during RCF via transesterification with the methanol solvent, ,, whereas the formation of 4-propanol-(and 4-propenyl-/4-propyl-)­substituted monomers was reported to occur via hydrogenation (and a combination of hydrogenolysis and hydrogenation) of 4-propenol-substituted lignin units . On the other hand, the production of 4-ethyl-substituted monomers was explained by: (i) the hydrogenation of 4-vinyl-substituted monophenolics formed via decarboxylation of coumarates and ferulates, , (ii) the dehydrogenation and subsequent decarbonylation of 4-propanol-substituted monomers, , and (iii) the occurrence of dealkylation reactions . The marginal presence of 4-methyl-substituted monomers and of species lacking alkyl side chains was associated with the occurrence of dealkylation reactions. , Scheme S1 illustrates the main reaction pathways that we propose for the formation of monophenolics during the RCF of wheat straw on the basis of previous works. ,,, …”

“…On the other hand, the production of 4-ethyl-substituted monomers was explained by: (i) the hydrogenation of 4-vinyl-substituted monophenolics formed via decarboxylation of coumarates and ferulates, , (ii) the dehydrogenation and subsequent decarbonylation of 4-propanol-substituted monomers, , and (iii) the occurrence of dealkylation reactions . The marginal presence of 4-methyl-substituted monomers and of species lacking alkyl side chains was associated with the occurrence of dealkylation reactions. , Scheme S1 illustrates the main reaction pathways that we propose for the formation of monophenolics during the RCF of wheat straw on the basis of previous works. ,,, …”

“…of monophenolics during the RCF of wheat straw on the basis of previous works. 31,32,46,47 Next to the lignin oil, the water phase obtained after liquid− liquid extraction of the nonvolatile residue of the liquid fraction was subjected to acid hydrolysis (4 wt % H 2 SO 4 , 121 °C for 1 h) to convert alkylated sugars back to their parent sugars, 31 prior to being analyzed by HPLC (Figure S6) to inspect the presence of noncondensed carbohydrate derivatives generated from (hemi)cellulose decomposition (e.g., monoand oligosaccharides, polyols, organic acids, etc.). Low yields of organic acids (formic acid: 1.9 wt %, levulinic acid: 0.1 wt %), sugars (xylose: 1.1 wt %, glucose: 0.4 wt %), and diols (ethylene glycol: 1.0 wt %, 1,2-propylene glycol: 0.4 wt %) were measured (by total weight of polysaccharides in the initial biomass).…”

Reductive catalytic fractionation of wheat straw biomass

“…Scheme S1 Possible reaction pathways for the formation of monophenolics during the RCF of wheat straw. Based on Renders et al, 36 Anderson et al, 11 Li et al, 28 and Yamaguchi et al 37 S24 Scheme S2 Possible reaction pathways for the formation of non-condensed carbohydrate derivatives during the RCF of wheat straw. Based on Li et al, 38 Weingarten et al, 39 and Paksung and Matsumura.…”