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Ni-based catalysts are increasingly being used in nitrobenzene hydrogenation. How to select suitable catalyst supports is crucial for upgrading the catalytic performance. Herein, three Ni-based catalysts supported on activated carbon fiber (ACF), mesoporous carbon black (CB), and γ-Al2O3were tested for nitrobenzene hydrogenation. The influence of catalyst supports, their porosity characteristics, and reaction conditions on the catalytic performance was investigated. The results show that 10 wt % Ni/CB catalyst owns an ultrafine active Ni nanoparticles (∼10 nm) with a uniform dispersion and thus exhibits the optimal catalytic activity. The conversion of nitrobenzene and the selectivity to aniline could reach nearly 100% at 120 °C for 1 h. By contrast, it takes 2 h to achieve the same conversion for 10 wt % Ni/ACF at 120 °C, whereas 10 wt % Ni/Al2O3needs a severe reaction at 150 °C for 2 h. The turnover frequency of 10 wt % Ni/CB approaches 38 h–1, which is higher than those of other catalysts. Nitrobenzene hydrogenation over different catalysts conforms to a first-order reaction, and the apparent activation energy of 10 wt % Ni/CB (42.6 kJ/mol) is significantly lower than that of 10 wt % Ni/Al2O3(66.0 kJ/mol). Moreover, 10 wt % Ni/CB catalyst exhibits a good recyclability and structural stability owing to the existence of abundant mesopores in CB, in comparison with 10 wt % Ni/ACF and Ni/Al2O3. It is the mesopores rather than the micropores in carbon supports to postpone the deactivation of Ni-based catalysts. This work demonstrates the superiority of porous carbons as catalyst supports over Al2O3in nitrobenzene hydrogenation.

Hydrogen production for fuel cells via on-board steam reforming of methanol is a promising approach. In this study, an ammonium carbonate-assisted mechanochemical procedure has been developed for Cu-based catalyst synthesis for SRM. Catalytic performance in SRM was evaluated in a fixed bed reactor at varied conditions, and physical and structure properties of the catalysts were characterized by N2adsorption-desorption, N2O titration, SEM, H2-TPR, XRD and TG, etc. Mechanical milled samples exhibited a porous structure that differed from that of the catalyst prepared by conventional impregnation. The SRM activity was enhanced for the strong interaction between copper ions and the copper aluminate formed on the ball-milled catalysts. Cu1Zn3Al6exhibited the worst in activity, which could be ascribed to the poor metal dispersion. Cu–Al spinel in the catalysts plays an important role in the catalytic stability, which has prevented Cu from quick sintering in SRM, and the ball-milled catalysts have exhibited a slight deactivation with the time-on-stream of 25 ​h.

Due to the exhaustion of fossil fuels and environmental degradation, biodiesel has attracted much attention as a new energy source. Currently, microwave reactors are used extensively for producing biodiesel. However, nonuniform heating of producing biodiesel in microwave reactors is a major problem. In order to solve the problem, a microwave reactor with an interlayer which can obviously improve the uniformity of microwave heating was designed. In this work, the heating efficiency and heating uniformity of the reactor were discussed from two aspects of waveguide position and interlayer thickness by means of multi-physical coupling calculation. According to the calculation results, the optimization model of a microwave reactor with an interlayer was obtained. Then, based on the above optimization model of a microwave reactor with an interlayer, a stirrer that can improve the heat transfer of the fluid material was introduced. The Maxwell equation, heat transfer equation, and flow equation were coupled by the multi-physical field simulation method to explore the influence of different factors of the stirrer on power consumption and heating uniformity. Through response surface analysis, it was found that the primary and secondary order of stirring factors affecting microwave heating uniformity was stirring speed > impeller diameter > bottom clearance, and there was an interaction between different factors. From the two aspects of stirring power consumption and heating uniformity, the best stirring effect was obtained.

A mixture of multi-walled carbon nanotubes in an ethanol solution of Fe(NO3)3.9H2O and Co(NO3)2.6H2O, were used to prepare an Fe2O3-CoO catalyst supported on carbon nanotubes by a supercritical fluid drying method. The carbon encapsulated FeCo nanoparticles were prepared by the catalytic decomposition of methane over the catalyst at 850degC for 30 mins. The morphology and microstructure of the catalyst and carbon encapsulated nanoparticles (CEP) were characterized by XRD, FESEM, EDS and TEM analyses. The electromagnetic characteristics and microwave absorption properties of the CEP product were also studied. Results show that the CEP product possesses high complex permittivity and good permeability in the microwave frequency range from 2 to 18 GHz. The maximum absorption peak was observed at 9.44 GHz for a large reflection loss (R) of 13.3 dB, with a band width of 7.4 GHz and 2.56 GHz, at R <- 5 dB and R <- 10 dB, respectively.