Valorization of humin as a glucose derivative to fabricate a porous carbon catalyst for esterification and hydroxyalkylation/alkylation

• Published in: Waste management (Elmsford) 2020-02, Vol.103, p.407-415
• Main Authors: Yang, Jinfan, Niu, Xiaoru, Wu, Hao, Zhang, Hongyu, Ao, Zhifeng, Zhang, Sufeng
• Format: Article
• Language: English
• Subjects: Alkylation; Biomass; Carbon; Catalysis; Esterification; Glucose; Humic Substances; Humin; Porosity; Solid acid; Structure–function
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2020.01.004

[Display omitted] •Humin byproduct was firstly employed to fabricate carbonaceous solid acid catalyst.•This novel carbon possessed a porous structure and a high surface area.•The relationship between graphitization degree and SO3H density was discussed.•SO3H group was effective for both esterification and hydroxyalkylation/alkylation.•A renewable strategy for utilization of all components of lignocellulosic biomass. A challenge of today’s industry is to transform low-value side products into more value-added materials. The acid-catalyzed conversion of hemi(cellulose) to platform chemicals in green chemical/fuel production and biorefinery yields large formation of insoluble byproduct called humin. Herein, humin obtained from dehydration of glucose was transformed into a novel class of effective carbonaceous solid acid catalyst for the first time via low-temperature pyrolysis followed by sulfonation. A range of preparation conditions were investigated, and the structure-function relationships of the resulting catalysts were also discussed based on the analysis of structure and composition. Comparing with the glucose-derived carbon catalyst, the humin-derived catalyst has substantially larger surface area and higher SO3H density, which enable it to display higher catalytic activity and efficiency not only in esterification of levulinic acid and n-butanol (yield = 95.0%, 373 K), but also in hydroxyalkylation/alkylation of 2-methylfuran and furfural (yield = 64.2%, 323 K). Additionally, the catalyst could be repeatedly employed for at least four cycles without obvious deactivation, exhibiting good reusability. This work provides a green method to convert humin byproduct into economic and eco-friendly solid acid catalyst and may contribute to a holistic approach for biomass utilization.