Xiaoyan Dai

Ni-Co/Mg-Al catalyst derived from hydrotalcite-like compound prepared by plasma for dry reforming of methane

Abstract Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni, Co, Mg and Al, and their catalytic performance was investigated with dry reforming of methane. Experimental results showed that the hydrotalcite-like precursors could be completely decomposed and partly reduced by cold plasma jet, and the Ni-contained catalysts exhibited much higher activity than the catalyst without Ni. Especially, the catalyst with Ni/Co ratio of 8/2 achieved not only the highest conversions of 80.3% and 69.3% for CH 4 and CO 2 , respectively, but also the best stability in 100 h testing. The catalysts were characterized by XRD, XPS, TEM and N 2 adsorption techniques, and the results showed that the better performance of the 8Ni2Co bimetallic catalyst was attributed to its higher metal dispersion, smaller metal particle size, as well as the interaction effect between Ni and Co, which were brought by the special catalyst preparation method.

Carbon dioxide reforming of methane to synthesis gas by an atmospheric pressure plasma jet

Abstract An experimental investigation on CO2 reforming of CH4 to synthesis gas was performed using a novel atmospheric pressure plasma jet, which is initiated by an alternating current of 50 Hz and a high ratio transformer. The plasma jet proved to be a stable and uniform atmospheric pressure discharge that held the advantages of both thermal and nonthermal plasma. The effects of discharge distance, CH4:CO2 mol ratio in the feed, feed flow rate, and discharge power on the reforming reaction were investigated. The results showed that the products of the reforming reaction are simple, including H2, CO, a small amount of H2O, and carbon powder. The optimal discharge distance between two electrodes is 9 mm, and the optimal CH4:CO2 mol ratio is 4:6. When the flow rate is 1000 mL/min and the discharge power is 88.4 W, the conversions of CH4 and CO2 are 94.99% and 87.23%, respectively, which are higher than those via other plasmas. The conversions of CH4 and CO2 increase with increasing the discharge power and decrease with increasing the flow rate. Current process is more advantageous in treatment capacity and conversion ability for carbon dioxide reforming of methane than other plasma systems.

A Novel Reduction Method for Ni/γ-Al2O3 Catalyst by a High Frequency Cold Plasma Jet at Atmospheric Pressure

Abstract The Ni/γ-Al 2 O 3 catalyst was reduced by a high frequency cold plasma jet at atmospheric pressure. The performance of the catalyst for carbon dioxide reforming of methane was investigated. The process of catalyst reduction with plasma was quick and simple and was completed in only 10 min, giving activity and selectivity higher than those of the catalyst prepared by the conventional method. At the CH 4 /CO 2 molar ratio of 4/6 and the reaction temperature of 850°C, the methane conversion and CO 2 conversion reached up to 95.77% and 75.65%, respectively, and a hydrogen selectivity of 100% and a CO selectivity of 94.79% were obtained over the novel catalyst reduced by plasma. The novel catalyst exhibited good stability during a reaction test for 36 h. XRD characterization showed that only a metallic nickel phase and γ-alumina existed in the catalyst reduced by plasma, and the NiAl 2 O 4 phase and other nickel oxides were not detected. The nickel particle size of the catalyst was smaller than that of the conventional catalyst. An enhanced dispersion was achieved with the plasma reduction.

Ni/MgO catalyst prepared using atmospheric high-frequency discharge plasma for CO2 reforming of methane

Abstract A new type of Ni/MgO catalyst was prepared using atmospheric high-frequency discharge cold plasma. The influences of conventional method, plasma method, and plasma plus calcination method on the catalytic activity were studied and the CO 2 reforming of methane was chosen as the probe reaction. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy, and CO 2 temperature-programmed surface reaction techniques. The results suggested that the nickel-based catalyst prepared by plasma plus calcination method possessed a smaller particle size and a higher dispersion of active component, better low-temperature activity and enhanced anti-coking ability. The conversion of CO 2 and CH 4 was 90.70% and 89.37%, respectively, and the reaction lasted for 36 h without obvious deactivation under 101.325 kPa and 750 °C with CO 2 /CH 4 = 1/1.

Carbon Dioxide Reforming of Methane to Syngas by Warm Plasma: Low Energy Consumption

Experimental study of warm plasma reforming carbon dioxide and methane to syngas is presented. To achieve better plasma reforming methods for industrial chemical application, the characteristics of the different plasmas are reviewed. The warm plasma combines advantages of both thermal and non-equilibrium discharge, which is the more potential for industrial application than others plasmas, such as arc, DBD, corona. The effects of discharge distances between the electrodes, CH 4 /CO 2 ratio and flow rate on the reaction are investigated. The optimal discharge parameters of the reaction are achieved. Experiment results and comparison with other plasmas indicate the warm plasma has the advantage of low energy consumption.

Hydrogenolysis of methyl formate to methanol on copper-based catalysts and TPR characterization

Abstract It was found that Zr and B were effective promoters for Cu/Cr/Si catalyst with low Cr content used in the model reaction of hydrogenolysis of methyl formate to methanol. TPR, XRD results and the catalytic performance of catalysts were analyzed. It was indicated that there was an optimum Cu+/Cu0 ratio in the catalysts. The catalyst with 6 wt.% of Zr had lower reduction temperature and obtained the maximum yield of methanol at a lower temperature.

Preparation of trichlorosilane from hydrogenation of silicon tetrachloride in thermal plasma

A new method of producing trichlorosilane by hydrogenation of silicon tetrachloride with assistance of DC charged thermo-plasma was proposed. We have studied the dependence of degree of disassociation and ionization of hydrogen on temperature, as well as the function of heat capacity, via which the optimal volume and H2: SiCl4 molar ratio were confirmed. A DC power of 50 kW was equipped and the highest yield of trichlorosilane was above 70%, with an average yield about 60% and minimum unit energy expenditure about 3.2 kWh/kg for SiHCl3. This process is possible to be industrialized.