Dry reforming of methane on active and coke resistant Ni/Y_2Zr_2O_7 catalysts treated by dielectric barrier discharge plasma

In this study, Ni/YZrOcatalysts prepared with impregnation method and treated by dielectric barrier discharge plasma(DBD) in different atmospheres have been investigated for methane dry reforming. It is revealed by H-TPR that plasma treatment can enhance the interaction between Ni O/Ni particles and the YZrOpyrochlore support. Therefore, catalysts with smaller Ni O and Ni grains sizes, higher metallic Ni active surface areas can be achieved, as evidenced by XRD, TEM and Hadsorption-desorption measurements. As a consequence, the plasma-treated catalysts show significantly improved activity, stability and coke resistance, as testified by the TEM and TGA-DSC results. Plasma treatment in H/Ar gas mixture is found to be the best condition to prepare Ni/YZrO, which can be used to obtain a catalyst with the highest activity, stability and most potent coke resistance. It is believed that the smaller Ni grain size and higher metallic Ni active surface area induced by plasma treatment are the inherent reasons accounting for the promoted reaction performance of the Ni/YZrOpyrochlore catalysts.

Preparation of Ni/bentonite catalyst and its applications in the catalytic hydrogenation of nitrobenzene to aniline

Ni supported on bentonite was prepared by the impregnation method with different nickel contents, applied to the hydrogenation of nitrobenzene to aniline in a fixed-bed reactor, and it was characterized by X-ray diffraction（XRD）, H2-temperature programmed reduction（H2-TPR）, and X-ray photoelectron spectrometry（XPS）. The results showed that Ni/bentonite catalyst with 20 wt% nickel content provided a higher conversion of nitrobenzene and selectivity of aniline compared to other catalysts. NiO was the precursor of the active component of the catalyst, and the small crystallite size as well as the highly dispersed NiO on the Ni/bentonite-20 catalyst, contributed to the catalytic performance. The hydrogenation of nitrobenzene was carried out at 300℃ with a H_2 gaseous hourly space velocity of 4800 ml·（g cat）^-1·h^-1and a nitrobenzene liquid hourly space velocity of4.8 ml·（g cat）^-1·h^-1 over Ni/bentonite-20. A 95.7% nitrobenzene conversion and 98.8% aniline selectivity were obtained. While the nitrobenzene liquid hourly space velocity was 4.8 ml·（g cat）^-1·h^-1, the yield of aniline was more than 95.0% during a 10-hour reaction.

Catalytic methanation of syngas over Ni-based catalysts with different supports

Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.