Carbon-based solid acid catalyst derived from Undaria pinnatifida and its application in esterification

In this study, solid acid catalysts were prepared from a marine biomass, Undaria pinnatifida, also known as wakame, which is one of the hundred most invasive species worldwide. Carbonaceous materials from U. pinnatifida were prepared using sequential carbonization methods of pyrolysis and hydrothermal carbonization. The influence of these two carbonization methods on the characteristics of the solid acid catalysts was investigated. Catalysts prepared with a sequential carbonization method, pyro-hydrochar, exhibited the highest specific surface area while its sulfonated form showed good acidity of 2.14H+ mmol g−1. The catalytic performance of the prepared catalysts was evaluated through the esterification of acetic acid and ethanol. The catalyst derived from the sulfonated pyro-hydrochar presented higher catalytic activity than sulfonated pyrochar or hydrochar on its own. This study indicates that the sequential carbonization method is effective in producing carbonaceous material with great potential from U. pinnatifida that could be converted into highly efficient solid acid catalysts upon sulfonation.