Preparation of lignin-derived mesoporous carbon solid acid and its catalytic synthesis of furfural from xylan
Lignin-derived mesoporous carbon(MC-SO3H)solid acid was synthesized from sulfonation of mesoporous carbon,which was prepared by solvent evaporation-induced self-assembly method using lignin and phloroglucinol obtained from corn stalk extracted with acetone/water as carbon precursors and glyoxal as crosslinking agent,and characterized by SEM,XPS,elemental analyzer,N2 adsorption-desorption and acidity determination.With xylan conversion and furfural yield as indexes,the reaction conditions for MC-SO3H catalytic degradation of xylan to produce furfural were investigated,while the reason for MC-SO3H inactivation was further explored.The results showed that MC-SO3H exhibited a mesoporous surface area of 120.74 m2/g and an average pore size of 4.15 nm.Under the optimal reaction conditions of 1.0 g xylan,1.0 g MC-SO3H,30 mL γ-valerolactone as solvent,reaction temperature 180 ℃ and reaction time 10 min,the xylan conversion and furfural yield reached 90.0％and 79.5％,respectively.The total acidity of MC-SO3H(2.06 mmol/g)and—SO3H acidity(0.82 mmol/g)were the main sources of its catalytic activity.The main reason for the catalyst inactivation was attributed to the adhesion of unreacted xylans and degraded substances formed during the reaction on the catalyst,resulting in the decrease of total acidity and—SO3H acidity.When xylose instead of xylan was used,the xylose conversion and furfural yield could still reach 89.5％and 66.8％after repeated use for 4 times,indicating the good stability of MC-SO3H.
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