Carbonaceous Ti-incorporated SBA-15 with enhanced activity and durability for high-quality biodiesel production: Synthesis and utilization of the P123 template as carbon source

Abstract

A one-pot and environmental-friendly route to synthesizing carbonaceous Ti-SBA-15 materials as weakly Lewis solid acids for transesterification of Jatropha oil with methanol to high-quality Jatropha biodiesel fuel (BDF) was successfully developed. The chemical environment and location of Ti species were controlled by the molar ratios of hydrochloride (HCl) to titanium tetraisoproproxide (TTIP) in the Ti precursors. With a HCl/TTIP molar ratio of 2.5, the tetrahedrally coordinated Ti species with weakly Lewis acid character were maximized in the superficial areas and they were associated with the catalytically active sites for transesterification. The thin carbon film, which was derived from direct carbonization of the P123 template originally existed in the channeling pores of as-made materials without adding sugar or sulfuric acid, could keep mesoporous silica framework safe from leaching during the processing steps to make Jatropha BDF. As a result, the carbonaceous Ti-SBA-15 materials gave excellent activity and durability in synthesis of high-quality Jatropha BDF, which fulfills with the specification of the international fuel standard, in both batch-type and continuous fixed-bed reaction systems. By contrast, the conventional Ti-SBA-15 materials with bare and amorphous silica framework were instable in synthesis of Jatropha BDF, in which a large amount of silica species was eluted. Although the crystalline silica framework is relatively firmed, the commercial TS-1 zeolite gave moderate activity in synthesis of Jatropha BDF, associated with the slow molecular diffusion through the micropores. The powdered or extruded TiO2 nanoparticles with limited numbers of tetrahedrally coordinated Ti sites gave poor activities in synthesis of Jatropha BDF, and little amounts of silica and titania species from the contaminations were eluted into the Jatropha BDF.