Hui Lou

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.

La-based perovskite precursors preparation and its catalytic activity for CO2 reforming of CH4

Four perovskite-type precursors (LaNiO3, La2NiO4, LaCoO3 and La2CoO4) were successfully prepared by Pechini method and were characterized by X-ray powder diffraction (XRD), temperature-programmed reduction technique (TPR) and X-ray photoelectron spectroscopy (XPS). After reduction, their catalytic activity toward CO2 reforming of CH4 was tested in a fixed-bed reactor. It was found that Ni-based La2NiO4 catalyst, after calcinations at 850 or 1100 °C, was quite active and stable with CH4 conversion of 72% and 75%, respectively. It was proposed that the well-defined structure and La2O2CO3 phase might be responsible for the unusual catalytic behavior observed over the catalyst.

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.

One-step hydrogenation–esterification of furfural and acetic acid over bifunctional Pd catalysts for bio-oil upgrading

This contribution focuses on one-step hydrogenation-esterification (OHE) of furfural and acetic acid, which are difficult to treat and typically present in crude bio-oil, as a model reaction for bio-oil upgrading. A bifunctional catalyst is needed for OHE reaction. Among tested bifunctional catalysts, the 5%Pd/Al(2)(SiO(3))(3) shows the best catalytic performance. Compared to the physical mixture of 5%Pd/C+Al(2)(SiO(3))(3), there is a synergistic effect between metal sites and acid sites over 5%Pd/Al(2)(SiO(3))(3) for the OHE reaction. A moderate reaction condition would be required to obtain high yields of alcohol and ester along with lower byproduct yields. In this work, the optimum selectivity to desired products (alcohol and ester) of 66.4% is obtained, where the conversion of furfural is 56.9%. Other components, typically present in bio-oils, have little effects on the OHE of FAL and HAc. This OHE method is a promising route for efficient upgrading of bio-oil.

Upgrading of low-boiling fraction of bio-oil in supercritical methanol and reaction network.

In this work, the low-boiling fraction (LBF) of bio-oil was used as feed stock. LBF is a very complex mixture, and the three groups in LBF: acids, aldehydes and phenols, are primarily responsible for deterioration in the quality. The upgrading reactions were carried out over Pt/Al(2)(SiO(3))(3), Pt/C or Pt/MgO in supercritical methanol. It is demonstrated that supercritical condition can greatly facilitate the esterification process, and after 6 h reaction, all the acids can be converted into esters even without adding any catalyst. The total amount of the three groups left in products was much less exhibited on Pt supported on active carbon and MgO in the presence of hydrogen. By investigating the model reactions, the relations between the representative compounds and major products were identified, and the conversion scheme of the upgrading reactions is proposed.

Upgrading of high-boiling fraction of bio-oil in supercritical methanol

In this work, the upgrading reactions of high-boiling fraction (HBF) of bio-oil were carried out over a series of supported mono- and bi-metallic catalysts under the supercritical methanol condition. During these reactions, esterification and cracking (alcoholysis and hydrocracking) were the two dominant processes. PtNi/MgO exhibited good performance, and gave a high yield (72.4 wt.%) of refined oil. The acid-base properties of the supports have an important effect on the coke deposition on the catalyst surface. The acidic catalysts gave the somewhat lower product yields, but tended to inhibit coking reaction. This would improve the life of the catalysts in the practical applications. The refined oil is believed to be a potential substitute or partial substitute for the fossil transportation fuel.

energy-efficient coaromatization of methane and propane

Development of highly effective catalysts for one-stage conversion of methane with high selectivity to valuable products and energy efficiency will provide an efficient way to utilize natural gas and oil-associated gases and to protect environment. In recent years, there have been many efforts on direct catalytic transformations of methane into higher hydrocarbons by feeding additives together with methane under non-oxidative conditions. This paper reviewed the advances in recent research on non-oxidative aromatization of methane in the presence of propane over different modified HZSM-5 catalysts. The thermodynamic consideration, the isotope verification and the mechanism of the activation of methane in the presence of propane are discussed in the paper in detail.

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.

Dry (CO2) Reforming

Publisher Summary Carbon dioxide reforming (also known as dry reforming) is a method of producing synthesis gas (mixtures of hydrogen and carbon monoxide) from the reaction of carbon dioxide with hydrocarbons such as methane. This chapter introduces the recent progress in production of H2-rich synthesis gas via dry reforming of hydrocarbons (methane, ethane, propane, and n-octane) and oxygenates mainly on the basis of papers published after 2004. This process is attractive from the environmental and economical viewpoint because of the potential utilization of greenhouse gases as resources, but dry reforming of hydrocarbons is highly energy consuming. Dry reforming of methane is the largest and the most economical way to produce hydrogen. Dry (CO2) reforming of hydrocarbons, ethanol, and DME is a promising way to produce H2-rich synthesis gas. Several research papers on dry reforming of methane have been published, and great achievements are in progress. But there are still two main drawbacks that hinder the commercialization and application in large scale. One is that all these reforming reactions are endothermic, and the calculated enthalpy (ΔH) increases with the number of carbon atoms in hydrocarbons. Another is that the carbon deposition occurs easily even on the surface of noble metals, and the deposited carbon would cause deactivation. And yet many commercial operations include CO2 in the feed to their reformers to adjust syngas composition.Carbon dioxide reforming (also known as dry reforming) is a method of producing synthesis gas (mixtures of hydrogen and carbon monoxide) from the reaction of carbon dioxide with hydrocarbons such as methane. This chapter introduces the recent progress in production of H2-rich synthesis gas via dry reforming of hydrocarbons (methane, ethane, propane, and n-octane) and oxygenates mainly on the basis of papers published after 2004. This process is attractive from the environmental and economical viewpoint because of the potential utilization of greenhouse gases as resources, but dry reforming of hydrocarbons is highly energy consuming. Dry reforming of methane is the largest and the most economical way to produce hydrogen. Dry (CO2) reforming of hydrocarbons, ethanol, and DME is a promising way to produce H2-rich synthesis gas. Several research papers on dry reforming of methane have been published, and great achievements are in progress. But there are still two main drawbacks that hinder the commercialization and application in large scale. One is that all these reforming reactions are endothermic, and the calculated enthalpy (ΔH) increases with the number of carbon atoms in hydrocarbons. Another is that the carbon deposition occurs easily even on the surface of noble metals, and the deposited carbon would cause deactivation. And yet many commercial operations include CO2 in the feed to their reformers to adjust syngas composition.