Hydrodeoxygenation of potential platform chemicals derived from biomass to fuels and chemicals

Abstract

Biomass valorization has emerged as a promising and sustainable means of accommodating value-added chemicals. To produce such chemicals, various transformation methods of the top biomass-derived platforms nominated by the U.S....

Utilization of Ni as a Non-Noble-Metal Co-catalyst for Ceria-Supported Rhenium Oxide in Combination of Deoxydehydration and Hydrogenation of Vicinal Diols

“…The adjustment of the reaction time is necessary to obtain a good yield of 1,2-butanediol because 1,2-butanediol is also a reactive molecule in DODH (+ HG) and was converted to n -butane at a longer reaction time (Table S4), the reaction time was set much shorter than for the cases of the synthesis of mono-alcohols from glycerol or xylitol. These reaction results are similar to those obtained with the ReO x –Pd/CeO 2 catalyst (e.g., 1-pentanol and 3-pentanol formation in 83 and 16% yields, respectively, was reported from xylitol), and totally different from those of direct hydrogenolysis systems which produce more compounds with various number of oxygen atoms including monodeoxygenated and trideoxygenated compounds. ,, Metal-catalyzed hydrogenolysis of xylitol often involves C–C dissociation reactions, − which is in contrast to the present result. In the reaction of cis -1,2-cyclohexanediol, a longer reaction time is necessary to obtain high yields of cyclohexane as the DODH + HG product because of the isomerization to trans -1,2-cyclohexanediol which is not a reactive compound in DODH (entries 4 and 5).…”

“…One attractive reaction for selective removal of oxygen atoms is deoxydehydration (DODH), which is a one-step reaction that converts vicinal diols to alkenes, where compounds of high-valence metals such as Re and Mo are used as catalysts. − When DODH is combined with hydrogenation of the produced alkenes (DODH + HG), the products are alkanes, and the net reaction is formally dideoxygenation of vicinal diols. , The DODH reaction can be regarded as the reverse reaction of cis -dihydroxylation of alkenes, and it is only active for vicinal diols with cis-configuration. Based on stereoselectivity, DODH or DODH + HG can selectively give a single product from some cyclic polyhydroxy compounds such as methyl glycosides. , While typical DODH systems used homogeneous catalysts and expensive reducing agents such as PPh 3 and secondary alcohols, our group discovered heterogeneous catalyst systems of DODH or DODH + HG using H 2 as the reducing agent: ReO x –Au/CeO 2 − and ReO x –Ag/CeO 2 catalysts for DODH, and ReO x –Pd/CeO 2 for DODH + HG. ,− In these ReO x –M/CeO 2 systems, monomeric ReO x species on the CeO 2 support are the active centers for the production of alkenes from substrates, and the role of M is the activation of H 2 to reduce the ReO x species to complete the redox cycle. The general scheme of DODH (+ HG) over ReO x –M/CeO 2 catalyst systems is shown in Figure .…”

“…Based on stereoselectivity, DODH or DODH + HG can selectively give a single product from some cyclic polyhydroxy compounds such as methyl glycosides. 15,16 While typical DODH systems used homogeneous catalysts and expensive reducing agents such as PPh 3 and secondary alcohols, our group discovered heterogeneous catalyst systems of DODH or DODH + HG using H 2 as the reducing agent: ReO x −Au/CeO 2 17−19 and ReO x −Ag/ CeO 2 catalysts for DODH, 20 and ReO x −Pd/CeO 2 for DODH + HG. 13,21−23 In these ReO x −M/CeO 2 systems, monomeric ReO x species on the CeO 2 support are the active centers for the production of alkenes from substrates, and the role of M is the activation of H 2 to reduce the ReO x species to complete the redox cycle.…”

Acid hydrolysis of chitin in calcium chloride solutions

“…Biomass resources are renewable, abundant, widely available and inexpensive, serving as favorable alternatives to fossil feedstocks for energy and chemical production to mitigate carbon emission. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] Commercially available from shell waste, chitin is the world's second most abundant biomass (100 billion tons per year) with a linear and relatively homogeneous polymer structure mainly consisting of N-acetyl glucosamine (NAG) monomers linked by β-(1,4)-glycosidic bonds. [29][30][31][32][33][34] Chitin shares a similar structure to cellulose, but naturally bears the nitrogen element (as in the acetamido side chain), which offers a special platform resource to produce both organooxygen and organonitrogen chemicals.…”

Density Functional Theory Study of Deoxydehydration Reaction by TiO2-Supported Monomeric and Dimeric Molybdenum Oxide Catalysts

“…Deoxydehydration (DODH) reaction is one of the promising techniques in which hydroxy groups adjacent to the cis-form are simultaneously removed and converted to the corresponding CC bond in a single step, and it is useful for selectively converting functional groups of polyols. − The usefulness of DODH in comparison to other deoxygenation methods such as dehydration + hydrogenation lies in the unique regioselectivity; − however, the industrialization of DODH requires further improvements in many aspects, including reaction rate, catalyst cost, catalyst life, and separation efficiency of the product mixture. Several homogeneous catalysts have been developed, among which high-valent rhenium catalysts have been mainly investigated. ,, Molybdenum-based homogeneous catalysts have also been developed to replace the expensive rhenium catalysts, although they are generally less active than rhenium-based catalysts. − In these homogeneous catalysts, several types of alcohol have been used as the reducing agent to regenerate the catalysts.…”