Catalytic Hydrolysis of Polysaccharides Derived from Fast‐Growing Green Macroalgae

Abstract

Green macroalgae, such as Ulva spp., has a higher growth rate than terrestrial lingocellulosic biomass, which often leads to serious environmental issues such as green tide. So, it is a promising feedstock for biorefineries. Hiraoka produced Ulva with reproducible compositions and sizes by our original cultivation method. The macroalgae contained approximately 35 wt % of a soluble polysaccharide called ulvan, which is a sulfated glucuronorhamnan polysaccharide. The catalytic conversion of extracted ulvan was performed under hydrothermal conditions at 130 °C by using solid acid catalysts. The Amberlyst 70 catalyst has a stable structure and gave monosaccharides in quantitative yield, predominantly in the form of rhamnose. The Amberlyst 70 catalyst showed higher activity than sulfonated activated‐carbon (AC‐SO3H) in the hydrothermal conversion of ulvan, although Amberlyst 70 showed lower catalytic activity than AC‐SO3H in the hydrolysis of starch.

Insights into the Inhibition of Acidic Hydrolysis of Cellulose by Its Solation

“…Cellulose is the most abundant source of biomass and holds great potential as a vitally renewable alternative to fossil fuels for the sustainable production of biofuels and chemicals. − As the first step in cellulose transformation, direct and efficient hydrolysis of cellulose into glucose has received considerable attention because it is an extremely crucial entry point into the biorefinery concept. The hydrolysis of cellulose catalyzed by homogeneous acids has been widely investigated for a long time. − Although cellulose hydrolysis in liquid acids is accomplished with high efficiency, the liquid acids are replaced advantageously by solid acids, such as zeolites, − metal oxides, , polymeric catalysts, − magnetic catalysts, − and carbonaceous solid acids, − because heterogeneous catalysts are safe, less corrosive, environmentally benign, and recyclable. However, with either homogeneous or heterogeneous acid catalysts, crystalline cellulose suffers from low hydrolysis efficiency at mild temperatures (<160 °C) due to its robust structure.…”

Hydrolysis of Oligosaccharides and Polysaccharides on Sulfonated Solid Acid Catalysts: Relations between Adsorption Properties and Catalytic Activities

“… 11 − 17 A sulfonated activated carbon (AC-SO 3 H) catalyst pretreated under hydrothermal conditions at 200 °C and its catalytic activity for conversion of ball-milled cellulose into glucose under hydrothermal conditions at 150 °C also were reported. 11 , 17 Such sulfonated carbon catalysts were shown also for hydrolysis of various polysaccharides such as starch 17 − 21 and hemicellulose. 22 − 25 However, to develop environmentally friendly processes for biomass conversions, the sulfonated carbon catalysts are demanded to improve catalytic activity.…”

Aqueous-Phase Cellulose Hydrolysis over Zeolite HY Nanocrystals Grafted on Anatase Titania Nanofibers

“…In recent years, the homogeneous catalysts are replaced advantageously by heterogeneous solid acids catalysts, such as zeolites, 8,9 metal oxides, 10,11 polymeric catalysts, 12,13 magnetic catalysts, [14][15][16] and carbonaceous solid acids, 17,18 because heterogeneous catalysts are safe, easy separation, economic efficiency and environmental friendliness. In addition, heterogeneous catalysts often use ionic liquids as solvents for the hydrolysis reaction during the hydrolysis of cellulose to produce glucose.…”