No abstract

The second-generation biodiesel generated via deoxygenation of vegetable oils is an ideal green fuel compared to fossil fuels, and it can help address environmental pollution and the energy crisis. During the catalytic deoxygenation process of vegetable oils, the most critical core is the synthesis of catalysts with superior reaction performance. In this work, the catalyst design strategies including the selection of metal active species (non/noble metal and amorphous alloy catalysts), adjustment of coordination environment for metal active sites by metallic interstitial compounds, lattice sulfur and lattice oxygen, and regulation of the interface between metal sites and support were summarized systematically. This review is committed to providing fundamental understandings of catalytic mechanisms and insights into the catalyst design, thus guiding the catalyst synthesis for catalytic deoxygenation of vegetable oils and further boosting the industrialization process of second-generation biodiesel.

Enhancing the diffusion of reactants in catalysts is imperatively needed in the hydrodesulfurization process. However, diffusion properties of sulfur-containing compounds are poorly characterized owing to experimental limitations. Herein, molecular dynamics (MD) simulation was applied to explore diffusion properties of thiane, thiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene in mesoporous alumina with pore sizes of 11.8, 13.6, and 15.3 nm. It is found that larger pore size and higher temperature facilitate diffusion. In other words, with the increase of pore size and temperature, the self-diffusion coefficient increased while the average interaction energy dropped. Notably, the diffusion activation energy showed that diffusion of larger molecules was more sensitive to variations in pore size and temperature. Furthermore, the effect of the molecular structure on diffusion was also studied; the increase in the number of benzene rings and branched chains was detrimental to diffusion. The simulated results were demonstrated by our experimental findings and harbor tremendous guiding significance for the design of effective hydrodesulfurization catalysts.