Isomerization of glucose into fructose with homogenous amine-type base catalysts: amine structure, chain length, and kinetics

Libo Zhang,Nan Li,Hong Zhong,Bailian Deng

doi:10.1186/s40643-019-0271-7

Abstract

Three homogeneous organosilanes amine and aliphatic primary amine were used as amine catalysts to evaluate their catalytic activity and kinetic towards glucose isomerization. Catalysts structure (primary, secondary, tertiary amine), terminal groups and alkyl chain length were investigated and compared elaborately. Result showed organosilanes tertiary amine behaved the best and amine generated OH− and amine itself contributed the isomerization reaction. The generated acidic by-product not only decreased fructose selectivity but also affected glucose conversion kinetic. The effect of siloxane (–Si–O–CH3) substituent with methyl (–CH3) can be insignificant, but it provided guiding significance for selecting amine-type homogeneous or grafted amine catalysts for glucose isomerization reaction. Longer alkyl chain resulted in lower glucose conversion because of the alkyl chain curls that would weaken the amine catalytic effect and hydration ability. Catalyst loading and initial glucose concentration investigations further showed that amine would effectively catalyze the isomerization reaction under varied operational conditions. This work will provide more details about organic amine catalysts on glucose isomerization into fructose and promote synthesis of platform chemicals in the applications of biorenewable chemicals and fuel.

Highlights

With gradual depletion of traditional fossil resources, several promising biomass-derived products have been identified to be attractive due to the advantages of them being renewable, globally available, and environmentally friendly (Shen et al 2019)
The generated acidic by-product causes the decrease of fructose selectivity and reduced the glucose conversion kinetic
The substituent of siloxane (–Si–O–CH3) with methyl (–CH3) investigation showed in situ hydrolysis effect of –Si–O–CH3 group could be negligible, which provided guided significance for selecting amine-type homogeneous or grafted amine catalysts for the glucose isomerization reaction

Summary

Introduction

With gradual depletion of traditional fossil resources, several promising biomass-derived products have been identified to be attractive due to the advantages of them being renewable, globally available, and environmentally friendly (Shen et al 2019). The impact of tertiary amines alkyl substituents structure on their catalytic performance for the isomerization of glucose to fructose was studied (Deshpande et al 2019). First, three homogeneous amine type organosilanes amine (primary, secondary, and tertiary amine) were chosen as catalysts to screen their catalytic activity and catalytic kinetic towards glucose isomerization.

Results

Conclusion