Comparative Surface Study of Ru/Cu- and Ag/Cu-Doped RHS Catalysts from Waste Biomass for Biofuel Application

The present study compares the surface, textural, and catalytic properties of porous silica doped with bimetallic metal ions that was made from rice husk (RH) biomass. Due to the use of a surfactant during the synthesis process, porous RH-silica (RHS) was derived. In situ doping of silver/copper and ruthenium/copper has been achieved via the xerogel and hydrogel formation methods. The prepared catalysts have been analyzed by various methods, such as surface area and narrow pore size distribution, to confirm their porosity. Powder X-ray diffraction, Fourier transform infrared, and electron microscopy examination were further performed for physicochemical characterization of the synthesized materials. Transmission electron microscopy images showed that ruthenium and copper ions were incorporated perfectly, forming a hexagonal mesoporous (MCM-41) texture due to hydrogel formation and the method of preparation. Copper oxide nanoparticles with silver incorporation in RHS form cube-shaped particles for CuO formation on the surface of the silica matrix instead due to the method of preparation. In this case, ruthenium/copper-doped porous silica forms hexagon-shaped particles of RuO formation in the mesoporous matrix. Finally, the acetylation of glycerol using acetic acid on as-prepared catalysts has been studied. The catalytic activity increases with an increase in temperature and optimization of the molar ratio of glycerol and acetic acid. Increases in temperature result in higher selectivity toward triacetin formation instead of the conventional formation of monoacetin. Hence, we compared the surface physicochemical properties, catalytic conversion, and selectivity nature of bimetallic metal (Ru/Cu and Ag/Cu) ions incorporated in RHS prepared by different synthetic routes.