Sugar Hydrogenation Over Supported Ru/C—Kinetics and Physical Properties

Abstract

The hydrogenation kinetics of some natural sugars to corresponding sugar alcohols in aqueous solutions was investigated on Ru/C catalysts in a pressurized slurry reactor. The kinetic data were well described by a Langmuir-Hinshelwood model assuming that the hydrogenation step on the catalyst surface is rate determining. The density, viscosity and hydrogen solubility of the reacting liquid were measured. This information was used to estimate the liquid-phase diffusion coefficients, which were utilized in a reaction-diffusion-catalyst deactivation model for porous catalyst layers. The model indicated that diffusional resistance becomes severe for rather small catalyst particles and the model described the movement of the reactive front inside the particle during the reaction. The simulation results indicate that structured reactors would provide a better approach than the conventional fixed bed technology, if continuous operation is desired.

Support-Boosted Nickel Phosphide Nanoalloy Catalysis in the Selective Hydrogenation of Maltose to Maltitol

“…The catalytic hydrogenation of maltose is a reliable and straightforward method for the synthesis of maltitol, which is widely used as a sweetener and food additive and is the most in-demand sugar alcohol after d -sorbitol. − The selective synthesis of maltitol is challenging because the glycosidic bond linked to each carbohydrate is generally unstable under acidic or thermal conditions, resulting in easy hydrolysis to afford undesired glucose or its hydrogenated products . Using Ru-based catalysts, the selective hydrogenation of maltose to maltitol has been achieved under mild conditions without the cleavage of glycosidic linkages. − Although these catalysts are highly active, the noble metals are rare and expensive. Alternatively, inexpensive and abundant non-noble-metal catalysts, i.e., Raney Ni catalysts, have been reported for maltose hydrogenation. − However, Raney Ni catalysts have serious drawbacks, such as instability (pyrophoricity), low activity, and difficulties in reuse.…”

Hydrolysis of semi‐industrial aqueous extracted xylan from birch (Betula pendula) employing commercial catalysts: kinetics and modelling

“…The side groups are glucuronic acids and some other sugars such as galactose, rhamnose and mannose. Xylose is the main monosaccharide obtainable from xylan via hydrolysis and it can be utilized as an important platform molecule, which can be valorized to (for example) xylitol via hydrogenation, 9,10 to furfural via dehydration or to xylonic acid through oxidation. These compounds can be utilized in a wide variety of biochemicals for use in such industries as the paper, alimentary, cosmetic and pharmaceutical.…”

“…In addition, a further dehydration to furfural is possible under harsher conditions. 10,[17][18][19] The formation of the covalent bond between the oxygen atom of the water and the carbon of the polysaccharide is the rate-determining step in the reaction, which can be accelerated with a suitable catalyst. The hydrolysis can be carried out using homogeneous [20][21][22][23] or heterogeneous 24 catalysts.…”

Catalytic Hydrolysis of Polysaccharides Derived from Fast‐Growing Green Macroalgae

“…[4] In addition, rhamnulose derivatives, such as rhamnulose, rhamnitol, rhamnoic acid, and 5methyl-2-furfural, also have potentiala ss pecials weeteners in the flavor industry,a ss tabilization agents for bioactive compounds in pharmaceuticals, and as precursors of agrochemicals. [5] Green algae have been biorefined for the production of biofuels by applying processes such as solvolysis and hydrolysis combined with ethanol and lactic acid fermentation. [6] However,u lvan is not efficiently converted.B ecause enzymes generally requireh igh suitability for substrates ands how low reaction rates, highly active enzymes mustb ed eveloped with respect to each polysaccharide derived from macroalgae.…”

“…In conclusion, Amberlyst catalysts acceleratedt he hydrolysis of ulvan and quantitatively gave approximately 40 C% yield of rhamnose. Ulvan,w ith al ow molecular weight, and oligosac- (3), 10 min (4), 30 min (5), and before the reaction (1). Reactionc onditions: reaction temperature:130 8C, catalyst:2 0mg, 0.5 wt %a queoussolutions: 2mL.…”