Shenglan Liu

A nano-sized solid acid synthesized from rice hull ash for biodiesel production

A nano-sized solid acid was synthesized from rice hull ash by acid activation. The solid acid was characterized by XRD, FT-IR, TEM and solid-state NMR spectroscopy. The characterization results show that the solid acid is amorphous silica with –OH and –SO3H functional acid groups. The TEM images show that the particle size range of the solid acid catalyst is 50–100 nm. In addition, the catalytic results indicate that the solid acid exhibits excellent activity and recyclability for the transesterification reaction of soybean oil with methanol, suggesting promising industrial applications in biodiesel production.

Effect of Surface Acid Properties of Modified VOx/Al2O3 Catalysts on Methanol Selective Oxidation

Effect of surface acid properties of HNO3 and NaOH modified VOx/Al2O3 catalysts on methanol selective oxidation was studied by solid-state nuclear magnetic resonance and X-ray powder diffraction (XRD) spectroscopy. The surface acidity including type and strength of the acid sites in the catalysts was characterized by the adsorption of probe molecules. Compared with the VOx/Al2O3 catalyst, stronger Brønsted acid sites on the acid-treated VOx/Al2O3 catalyst lead to higher selectivity for DMM, while the base-treated VOx/Al2O3 catalyst with no Brønsted acid site gives rise to formate instead of DMM.Graphical AbstractProposed mechanism for methanol oxidation reaction over the VOx/Al2O3 catalysts. Methanol selective oxidation over VOx/Al2O3 catalysts with different surface acidity was studied. The XRD experimental results show that the bulk structure of the catalysts did not been changed by the acid or base modification. A significant selectivity to the reaction products as a function of the acid properties of the catalysts was observed. Comparing to the VOx/Al2O3 catalyst, stronger Brønsted acid site on the acid-treated VOx/Al2O3 catalyst leads to higher selectivity for dimethoxymethane, while the base-treated VOx/Al2O3 catalyst with no acid site gives rise to formate instead of dimethoxymethane.