Enhanced Hydrolysis of Cellulose in Ionic Liquid Using Mesoporous ZSM-5.

Tianlu Chen,Chunrong Xiong,Yousheng Tao

doi:10.3390/molecules23030529

Tianlu Chen, Chunrong Xiong + Show 1 more

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https://doi.org/10.3390/molecules23030529

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Abstract

Mesoporous ZSM-5 prepared by alkaline treatment was demonstrated as an efficient catalyst for the cellulose hydrolysis in ionic liquid (IL), affording a high yield of reducing sugar. It was demonstrated that mesoporous ZSM-5 (SiO2/Al2O3 = 38) had 76.2% cellulose conversion and 49.6% yield of total reducing sugar (TRS). In comparison, the conventional ZSM-5 had a mere 41.3% cellulose conversion with 33.2% yield of TRS. The results indicated that the important role of mesopores in zeolites in elevating the TRS yield may be due to the diffusional alleviation of cellulose macromolecules. The effects of reaction time, temperature, and the ratio of catalyst to cellulose were investigated for optimal reaction conditions. It was found that IL could enter the inner channel of mesoporous ZSM-5 to promote the generation of H+ from Brönsted acid sites, which facilitated hydrolysis. Moreover, the mesoporous ZSM-5 showed excellent reusability for catalytic cycles by means of calcination of the used one, promising for its practical applications in the hydrolysis of cellulose.

Highlights

The conversion of renewable biomass into useful chemicals is of importance in green and sustainable chemistry [1,2,3]
We investigated the reaction conditions and catalyst reusability and demonstrated the role of mesopores in elevating the yield of total reducing sugar (TRS)
The X-ray diffraction (XRD) patterns of the parent ZSM-5 and the alkaline-treated ZSM-5 are shown in Figure fingerprintsof ofzeolite zeoliteafter afteralkaline alkalinetreatment treatmentwere weremaintained, maintained, suggesting that crystalline phases fingerprints suggesting that thethe crystalline phases of of zeolite not change the alkaline treatment

Summary

Introduction

The conversion of renewable biomass into useful chemicals is of importance in green and sustainable chemistry [1,2,3]. Cellulose is the most abundant source of biomass. Breakage of 1,4-β-glycosidic bonds by acids to hydrolyze cellulose into reducing sugar is a key process for the use of cellulose. Efforts with mineral acids [6], enzymes [7], and supercritical water [8] have been devoted to cellulose hydrolysis. There are distinct drawbacks in these traditional methods, such as the corrosion of reactors, the high cost of enzymes, harsh reaction conditions, and difficult separation of the products [9,10]. Solid acid catalysts have advantages of easy product separation, recyclability, and little damage of the reactor [11,12,13,14,15,16]

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