Green synthesis of aluminum-hydrochar for the selective isomerization of glucose to fructose

摘要

Hydrochar microspheres supported Al catalysts with hierarchically porous structure (Al/HPHMs) for glucose to fructose isomerization were fabricated. Superior catalytic selectivity (93.3%) and fructose yield (32.6%) were achieved in aqueous under 160 °C for 20 min. Hierarchically porous structure was formed after KHCO_3 and K_2CO_3 activation and the roles of KHCO_3 and K_2CO_3 in controlling the Al phase and tailoring morphology of hydrochar supported Al were evaluated. The major active sites were characterized as Al hydroxides including β-Al(OH)_3, γ-Al(OH)_3, γ-AlO(OH), Al-C-0 linkages. Active sites by KHCO_3 activation with high contents of Al-C-O and Al(OH)_3 have better selectivity. Oxygen-containing functional groups including aluminum-oxygen groups on the hydrochar microspheres have contributed to the formation of hydrogen bond and π-π interactions between glucose and Al species. Green process synthesized aluminum-hydrochars have potential for their application as a variety of stable, recyclable, and efficient catalysts for lignocellulosic biorefining.