High yield of renewable hexanes by direct hydrolysis–hydrodeoxygenation of cellulose in an aqueous phase catalytic system

Abstract

In aqueous phosphoric acid, cellulose was efficiently converted into hexanes using a Ru/C catalyst combined with layered compounds or silica-alumina materials. In this process, the direct production of hexanes from cellulose can be improved by suppressing the formation of isosorbide, which makes it difficult to yield hexanes by further hydrodeoxygenation. As the co-catalyst, layered compounds showed a significant inhibition effect on the formation of isosorbide from sorbitol due to the steric restrictions of sorbitol dehydration within the interlayers of layered compounds. Typically, layered LiNbMoO 6 played a great role in promoting the production of hexanes directly from cellulose and a promising yield (72% carbon mol) of hexanes was obtained. In addition, the protonic acid, H 3 PO 4 , offered efficient catalysis for the hydrolysis of cellulose and the dehydration of the sorbitol hydroxyl moiety.Scheme 1 Direct catalytic conversion of cellulose into hexanes over Ru/C combined with LiNbMoO 6 in aqueous phosphoric acid. Scheme 2The efficient conversion of cellulose to hexanes over LiNbMoO 6 and Ru/C in aqueous phosphoric acid.This journal is

One-Pot Catalytic Conversion of Raw Lignocellulosic Biomass into Gasoline Alkanes and Chemicals over LiTaMoO6 and Ru/C in Aqueous Phosphoric Acid

“…20 In this system, isosorbide was the most robust intermediate, which corresponded to former studies. 11,17,26 Numerous research efforts suggested Ru/C catalyzed hydrogenation and acid-catalyzed hydrolysis and dehydration played important roles in the formation of alkanes. 11,27−31 But the addition of layered compounds was crucial because they could dramatically suppress the formation of isosorbide.…”

“…Sels and co-workers investigated conversion of cellulose to gasoline alkanes (nhexane, methylcyclopentane and n-pentane) by using H 4 SiW 12 O 40 -modified Ru/C (htRu/C) and H 4 SiW 12 O 40 catalytic system in water/n-decane. 11 In contrast, they proposed gasoline alkanes were mainly yielded from a different route, which they called the HMF (5-hydroxymethylfurfural) route. In this route, HMF, produced from dehydration of cellulose derived glucose, was the main intermediate that was transformed into gasoline alkanes via consecutive hydrogenation/ hydrogenolysis.…”

“…Pyrolysis or hydropyrolysis of biomass toward liquid fuel was a promising route; 8,33−36 catalytic conversion of biomass to gasoline alkanes should not be underestimated for its high carbon efficiency. 11 Sels and co-workers used the same catalytic system of htRu/C+H 4 SiW 12 O 40 to convert softwood to gasoline alkanes with a yield of 60%. 11 Apart from cellulose and hemicellulose, lignin, on the other hand, is an amorphous, highly crossed-linked polymer that consists of phenyl propylene units.…”

“…11 Sels and co-workers used the same catalytic system of htRu/C+H 4 SiW 12 O 40 to convert softwood to gasoline alkanes with a yield of 60%. 11 Apart from cellulose and hemicellulose, lignin, on the other hand, is an amorphous, highly crossed-linked polymer that consists of phenyl propylene units. Lignin is the most abundant source of aromatic compounds that should be fully exploited to produce aromatics or fuels.…”

“…In this route, HMF, produced from dehydration of cellulose derived glucose, was the main intermediate that was transformed into gasoline alkanes via consecutive hydrogenation/ hydrogenolysis. 11,21−25 Although a biphasic system may function to separate intermediates or products, or to suppress undesirable reactions, 11 the aqueous phase should be fully addressed as the solvent because it is readily available. Therefore, we employed the Ru/C + layered compound + phosphoric acid system to convert directly cellulose into hexanes in aqueous phase.…”