The sulfonated natural silica-based catalyst prepared from rice straw for hydrolysis of microcrystalline cellulose

Abstract

A sulfonated silica-based catalyst (SSRS-Cat) was prepared from rice straw (RS) and its performance on the hydrolysis of pretreated microcrystalline cellulose (PMCC) was investigated by determining glucose and total reduced sugars (TRS) yields. The physicochemical and morphological properties of SSRS-Cat were investigated with scanning electron microscopy–energy-dispersive X-ray (SEM–EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer–Emmet–Teller (BET) analysis. The total acidic site density in SSRS-Cat was assessed using NH₃ temperature-programmed desorption (NH₃-TPD) analysis, and also, elemental CHNS analysis was used for the determination of the SO₃H amount in the catalyst. A porous structure with a surface area of 467.38 m²/g and total and sulfonic acidic functional groups with densities of 1.31 and 0.13 mmol/g was observed for the SSRS-Cat sample. The influence of different parameters such as temperature (130, 150, and 170 °C), time (1, 2, 3, and 4 h), and catalyst-to-substrate ratio (C/S) (0, 0.25, 0.5, and 1 g/g) was investigated on the hydrolysis performance of SSRS-Cat. The maximum TRS yield of PMCC was achieved about 51.89% in a C/S ratio of 0.5 g/g at 150 °C after 3 h. But the highest glucose yield of 35.24% was obtained after 2 h with a C/S ratio of 0.5 g/g at 150 °C. The synthesized SSRS-Cat was reused three times with a moderate loss of its catalytic performance. So that the glucose efficiency was decreased by about 25% after three times of catalyst recovery.