Fabrication of a solid superacid with temperature-regulated silica-isolated biochar nanosheets

Publication date: April 2020Source: Chinese Journal of Catalysis, Volume 41, Issue 4Author(s): Zengtian Chen, Yuxue Xiao, Chao Zhang, Zaihui Fu, Ting Huang, Qingfeng Li, Yuanxiong Yao, Shutao Xu, Xiaoli Pan, Wenhao Luo, Changzhi LiAbstractThis paper reports a new strategy for the structural reconstruction of biomass carbon sulfonic acid (BCSA) to its solid superacid counterpart. In this approach, a cheap layered biomass carbon (BC) source is chemically exfoliated by cetyltrimethyl ammonium bromide and then converted to silica-isolated carbon nanosheets (CNSs) by a series of conversion steps. The state of the silica-isolated CNSs and the stacking density of their nanoparticles are regulated by the dehydration temperature. Only the highly isolated and non-crosslinked CNSs with loose particle stacking structures obtained upon dehydration at 250 °C can be turned into superacid sites (with stronger acidity than that of 100% H2SO4) after sulfonation. This is accompanied by the creation of abundant hierarchical slit pores with high external surface area, mainly driven by the strong hydrogen bonding interactions between the introduced sulfonic acid groups. In typical acid-catalyzed esterification, etherification, and hydrolysis reactions, the newly formed superacid exhibits superior catalytic activity and stability compared to those of common BCSA and commercial Amberlyst-15 catalysts, owing to its good structural stability, highly exposed stable superacidic sites, and abundance of ...
Source: Chinese Journal of Catalysis - Category: Chemistry Source Type: research