The
characterization results indicate that such solid acid catalyst mainly consists of four building blocks: the
condensed aromatic carbon sheets, the active groups (including ASO3H, ACOOH and phenolic OH), the
side chains (including ACH3 and AOCH3) and the bridge linkages (including AOA, ACH2A, ACH2ACH2A,
and AOCH2A) acting as the intermediates between aromatic clusters