Microcrystalline cellulose (MCC) was purchased from Sigma-Aldrich (Saint Louis, MO, USA). The chemical compositions of the native cellulose determined according to the ASTM/TAPPI standard protocols are shown in Table 4. The hydrolyzing catalysts used in this study, namely sulfuric acid (H2SO4, 95%–97% purity) and chromium (III) nitrate (Cr(NO3)3), were bought from Merck (Kuala Lumpur, Malaysia). All chemicals were of analytical grade and used as received without further purification.