Heteropoly Acid-Based Catalysts for Hydrolytic Depolymerization of Cellulosic Biomass.

Xiaoxiang Luo,Hu Li,Zhengyi Li,Yaqiong Su,Song Yang,Heng Zhang,Yan Li,Hongguo Wu,Chuanhui Li

doi:10.3389/fchem.2020.580146

Xiaoxiang Luo, Hu Li + Show 7 more

Open Access

https://doi.org/10.3389/fchem.2020.580146

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Abstract

Cellulose is the most abundant source of biomass, which can be converted into monosaccharide or other chemical platform molecules for the sustainable production of chemicals and fuels. Acid catalysts can promote hydrolytic degradation of cellulose into valuable platform molecules, which is of great significance in the development of chemicals and biofuels. However, there are still some shortcomings and limitations of the catalysts for the hydrolytic degradation of cellulosic biomass. Heteropoly acid (HPA), as a green catalyst, seems to be more conducive to the degradation of cellulosic biomass due to its extreme acidity. HPAs can be designed in homogeneous and heterogeneous systems. Moreover, they can be easily separated from the products in both systems by a simple extraction process. According to the unique properties of HPAs (e.g., good solubility, high thermal stability, and strong acidity), using heteropoly acid-based catalysts to depolymerize and convert cellulose into value-added chemicals and biofuels has become one of the most remarkable processes in chemistry for sustainability. In this review, the characteristics, advantages, and applications of HPAs in different categories for cellulose degradation, especially hydrolysis hydrolytic degradation, are summarized. Moreover, the mechanisms of HPAs catalysts in the effective degradation of cellulosic biomass are discussed. This review provides more avenues for the development of renewed and robust HPAs for cellulose degradation in the future.

Highlights

With the continuous exploitation of human beings, the amount of fossil energy that is the most main energy consumed in the world is decreasing gradually
Given the unique features and rapid development of HPAsbased catalysts in the preliminary degradation of cellulosic biomass with high efficiency, this review mainly reports the design and structural characterization of different types of Heteropoly acid (HPA) employed for hydrolytic depolymerization of cellulosic biomass
The results showed that using H4SiW12O40 as a catalyst, glycogen could be completely converted into glucose by the autoclave method and sonication method without other by-products, so relatively high selectivity toward glucose (>99%) was obtained using these two methods

Summary

INTRODUCTION

With the continuous exploitation of human beings, the amount of fossil energy that is the most main energy consumed in the world is decreasing gradually. Developing a sustainable renewable energy source that can provide valuable chemicals and biofuels is of great importance (Zhang et al, 2015). SCHEME 1 | Biorefinery for the development of industrially relevant products. As the most abundant source of biomass and one of the most widely distributed and abundant polysaccharides in nature, cellulose provides more possibilities for sustainable chemicals and fuels in the future (Huber et al, 2006; Climent et al, 2014; Sheldon, 2014; To et al, 2015). The conversion of cellulose could become a significant part of biomass utilization, which plays an important role in the development of chemicals and fuels in the future. Many homogeneous and heterogeneous acid catalysts were found to be capable of converting cellulose into glucose, a monosaccharide which is an important component for SCHEME 3 | The main reaction network of glucose hydrogenation and oxidation

SiW12 O40

PV14 O42

Method

Findings

CONCLUSIONS AND OUTLOOK