Composite coal fly ash solid acid catalyst in synergy with chloride for biphasic preparation of furfural from corn stover hydrolysate

Abstract

A solid acid catalyst SO₄^2-/SnO₂-Al₂O₃-CFA was synthesized based on industrial waste coal fly ash (CFA) as carrier and applied in the conversion of oxalic acid pretreated corn stover hydrolysate to produce furfural. Physical properties of the solid acid catalyst were characterized by SEM, FTIR, XRD, BET, EDAX, and NH₃-TPD. Highly wrinkled structure of SO₄^2-/SnO₂-Al₂O₃-CFA could provide more specific surface area for the covalent linkage between SiO₂ and SnO₂. Factors influencing the efficacy of SO₄^2-/SnO₂-Al₂O₃-CFA were systematically explored. The highest furfural yield of 84.7% was reached in NH₄Cl-toluene biphasic system at 180 °C for 30 min. The recyclability of SO₄^2-/SnO₂-Al₂O₃-CFA and toluene could be achieved for five batches with stable performance in transformation of xylose-rich corn stover hydrolysate. This study provided a novel solid acid catalyst with promising potential in the synthesis of furfural from corn stover.

Keywords: Biphasic system; Chloride salt; Corn stover hydrolysate; Furfural; Solid acid catalyst.