玉米秸秆衍生碳基固体酸的制备及其催化纤维素水解糖化

以玉米秸秆为原料，通过碳化-磺化法制备了碳基固体酸（CSA），采用XRD、FTIR、XPS、SEM、阳离子交换与返滴定法等手段对其结构形貌进行表征，并考察了制备条件对固体酸表面活性基团含量与催化活性的影响。以NaOH/尿素冻融预处理后的纤维素为底物，研究了CSA催化纤维素水解糖化的效果与条件。结果表明：NaOH/尿素冻融预处理能够有效辅助固体酸催化纤维素水解，在350℃碳化2h、100℃磺化5h条件下制备的CSA催化性能最好，其酸量达3.94mmol/g，其中磺酸基、羧基、酚羟基含量分别为1.09mmol/g、1.36mmol/g、1.49mmol/g。在m(CSA)∶m(纤维素)=3∶1、水解温度200℃、水解时间为0.5h的条件下，纤维素水解还原糖得率与转化率分别为47.1%和63%。CSA循环利用3次催化活性下降不大。本研究可为废弃生物质原料制备的固体酸催化纤维素水解转化利用提供科学参考。

Preparation of carbon-based solid acid derived from corn stalk and its catalytic performance in hydrolysis and saccharification of cellulose

Carbon-based solid acid (CSA) was successfully prepared through a carbonization-sulfonation process using corn stalk as the raw material. The structure and morphology were characterized by XRD, FTIR, XPS, SEM, and cation exchange and back titration. The influence of preparation conditions on the content of active groups and catalytic activity of solid acid was investigated. With cellulose freeze-melting pretreated by NaOH/urea as the substrate, the conditions and effects of hydrolysis and saccharification catalyzed by CSA were carefully studied, and it was found that the NaOH/urea freeze-melting pretreatment could effectively assist the solid acid to catalyze the hydrolysis of cellulose. The CSA prepared under carbonization at 350℃ for 2h and sulfonation at 100℃ for 5h showed the best catalytic performance. The amount of acid was 3.94mmol/g, and the contents of sulfonic group, carboxyl group and phenolic hydroxyl group were 1.09mmol/g,1.36mmol/g and 1.49mmol/g, respectively. Under the conditions of m(CAS)∶ m(cellulose)=3∶1, hydrolysis temperature=200℃, and hydrolysis time=0.5h, the reducing sugar yield and conversion of cellulose were 47.1% and 63.0%, respectively. After recycled for 3 times, the catalytic activity of CSA was decreased slightly. This study can provide a scientific reference for the hydrolysis, conversion and utilization of cellulose catalyzed by solid acid prepared from waste biomass.