▎ 摘　　要

NOVELTY - A carbonaceous material comprises an amorphous carbon containing a graphene sheet. The carbonaceous material has a sulfo group, ratio (S/C) of sulfur atom with respect to carbon atom of 0.005-0.15, and has peak temperature of 175-200 degrees C and number of acid sites calculated from quantity of ammonia desorbed at 100-400 degrees C of 30 mu mol/g or more, in ammonia temperature-programmed desorption. USE - Carbonaceous material is used for solid acid for hydrolyzing cellulose, and adsorption agent (all claimed). ADVANTAGE - The porous carbonaceous material has numerous acid sites. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) solid acid; (2) manufacture of carbonaceous material, which involves mixing a water-soluble metal salt and water-soluble polysaccharide in presence of water, obtaining mixture (A), carbonizing the mixture (A), and performing sulfonation of obtained carbonized material; and (3) hydrolysis of cellulose, which involves hydrolyzing cellulose using the solid acid as a catalyst.