Jinzhao Duan

Transesterification of sunflower oil to biodiesel on ZrO2 supported La2O3 catalyst

ZrO(2) supported La(2)O(3) catalyst prepared by impregnation method was examined in the transesterification reaction of sunflower oil with methanol to produce biodiesel. It was found that the catalyst with 21 wt% loaded La(2)O(3) and calcined at 600 degrees C showed the optimum activity. The basic property of the catalyst was studied by CO(2)-TPD, and the results showed that the fatty acid methyl ester (FAME) yield was related to their basicity. The catalyst was also characterized by TG-DTA, XRD, FTIR, SEM and TEM, and the mechanism for the formation of basic sites was discussed. It was also found that the crystallite size of support ZrO(2) decreased by loading of La(2)O(3), and the model of the solid-state reaction on the surface of La(2)O(3)/ZrO(2) catalyst was proposed. Besides, the influence of various reaction variables on the conversion was investigated.

Nanostructured molybdenum carbides supported on carbon nanotubes as efficient catalysts for one-step hydrodeoxygenation and isomerization of vegetable oils

Nanostructured molybdenum carbides supported on multi-walled carbon nanotubes (Mo2C/CNTs) with different loadings were prepared by carbothermal hydrogen reduction method and characterized with SEM, Raman, HAADF-STEM and XRD. Raman spectra showed that the specific G-band structure of carbon nanotubes promoted the formation of molybdenum carbide at lower temperatures. Compared with noble metals, molybdenum carbide exhibited better catalytic activity and resistance to leaching. The Mo2C/CNTs catalyst also showed high activity and selectivity for one-step conversion of vegetable oils into branched diesel-like hydrocarbons, which provided a promising approach to prepare high-grade diesel fuels from renewable resources.

Carbon-Supported Molybdenum Carbide Catalysts for the Conversion of Vegetable Oils

Ordered mesoporous carbon (OMC)-supported molybdenum carbide catalysts were successfully prepared in one pot using a solvent-evaporation-induced self-assembly strategy accompanied by a carbothermal hydrogen reduction reaction. Characterization with nitrogen sorption, small-angle XRD, and TEM confirmed that the obtained materials had high surface areas, large pore volumes, ordered mesoporous structures, narrow pore size distributions, and uniform dispersions of molybdenum carbide particles. With nitrogen replaced by hydrogen in the carbothermal reduction reaction, the formation temperature of molybdenum carbide could be reduced by more than 100 °C. By changing the amount of molybdenum precursor added from less than 2 % to more than 5 %, molybdenum carbide structures could be easily regulated from Mo(2) C to MoC. The catalytic performance of OMC-supported molybdenum carbide catalysts was evaluated by hydrodeoxygenation of vegetable oils. Compared with Mo(2)C, MoC exhibited high product selectivity and excellent resistance to leaching in the conversion of vegetable oils into diesel-like hydrocarbons.

Carbon nanofibers supported molybdenum carbide catalysts for hydrodeoxygenation of vegetable oils

Carbon nanofiber-supported molybdenum carbide catalysts (Mo2C/CNF) with different loadings were prepared by the carbothermal hydrogen reduction method. Characterizations with Raman, XRD, N2-TGA, SEM, TEM and HAADF-STEM confirmed that Mo2C nanoparticles were successfully supported on the carbon nanofibers. The optimal reaction conditions with model compounds on Mo2C/CNF had a conversion of 98.03% and yield of 95.26%. It is interesting to note that a low evaporation rate positions the Mo2C nanoparticles on the outside of the CNF due to the capillary effect and the Mo2C nanoparticles on the outside of the CNFs showed high catalytic activity compared to ones on the inside of the CNFs. The Mo2C/CNF catalyst was recycled 5 times without any apparent loss of catalytic activity. Catalytic performances of Mo2C/CNF, Mo2C/AC (activated carbon) and Mo2C/CNT (multi-walled carbon nanotubes) were examined using methyl palmitate and maize oil. The results showed that molybdenum carbide could be a potential substitute for noble metals in transformation of vegetable oils.

Carbon‐Supported Molybdenum‐Based Catalysts for the Hydrodeoxygenation of Maize Oil

The hydrodeoxygenation (HDO) of maize oil was performed in an autoclave with Mo‐based catalysts supported by different carbon materials, such as reduced graphene oxide, activated charcoal, graphite, and fullerene. Nanostructured Mo‐based catalysts with different phase compositions were prepared by using the carbothermal hydrogen reduction method at temperatures ranging from 500 to 700 °C and characterized by Raman spectroscopy, N2 adsorption isotherms, SEM, TEM, XRD, X‐ray photoelectron spectroscopy, and ammonia temperature‐programmed desorption. The highest total hydrocarbon yield of 90.32 % was obtained on the reduced graphene oxide‐supported molybdenum carbide catalyst at 700 °C. These results are subject to the complicated effect of different factors such as phase composition, defect concentration, and particle size on the catalytic behavior of the materials. Unique structures of different supports also play a significant role in the HDO reaction. On the basis of the results of comprehensive analysis of products and catalysts, an HDO mechanism was proposed. These Mo‐based catalysts are a promising system to prepare high‐quality diesel fuels from renewable resources.