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Unraveling the hydrolysis of β-1,4-glycosidic bonds in cello-oligosaccharides over carbon catalysts
Catalysis Science & Technology ( IF 5 ) Pub Date : 2020-06-16 , DOI: 10.1039/d0cy00783h
Pengru Chen 1, 2, 3, 4, 5 , Abhijit Shrotri 1, 2, 3, 4 , Atsushi Fukuoka 1, 2, 3, 4
Affiliation  

Carbon catalysts having weakly acidic groups are uniquely active for hydrolysis of cellulose to produce cello-oligosaccharides and glucose. Although adsorption of cellulose molecules on carbon is considered as the cause for this behavior, the effect of adsorption on the reaction is not well understood. In order to understand the underlying mechanism, we investigated the hydrolysis of cello-oligosaccharides with varying chain lengths over different catalysts. Carbon catalysts favored hydrolysis of larger oligosaccharides with an 11-fold increase in the reaction rate constant from cellobiose to cellohexaose. The activation energy required to cleave the glycosidic bonds was reduced concurrently with the increase in molecule size. Based on these data, in conjugation with the stronger affinity of adsorption for larger oligosaccharides, we propose that axial adsorption within the micropores of carbon causes conformational change in the structure of cello-oligosaccharide molecules, resulting in reduction of activation energy required to cleave the β-1,4-glycosidic bonds. Consequently, this translates to the higher rate of reaction for larger cello-oligosaccharides and explains the high reactivity of carbon catalysts towards cellulose hydrolysis.

中文翻译:

在碳催化剂上解开纤维寡糖中β-1,4-糖苷键的水解

具有弱酸性基团的碳催化剂对纤维素水解以产生纤维寡糖和葡萄糖具有独特的活性。尽管认为纤维素分子在碳上的吸附是造成这种现象的原因,但对反应的吸附效果尚不十分了解。为了理解潜在的机理,我们研究了在不同催化剂上链长不同的纤维寡糖的水解。碳催化剂有利于水解较大的寡糖,从纤维二糖到纤维己糖的反应速率常数增加11倍。裂解糖苷键所需的活化能与分子大小的增加同时降低。根据这些数据,结合较大的寡糖的更强的吸附亲和力,我们提出,碳微孔内的轴向吸附引起纤维寡糖分子结构的构象变化,从而导致裂解β-1,4-糖苷键所需的活化能降低。因此,这转化为较大的纤维寡糖的更高的反应速率,并解释了碳催化剂对纤维素水解的高反应性。
更新日期:2020-07-21
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