RESUMO
We have developed an in situ sample-holder-akin to a quartz-based plug-flow reactor-for vibrating sample magnetometry (VSM) in gas-controlled environments at ambient pressure and temperatures up to â¼1000 °C. The holder matches onto a specific type of vibrating sample magnetometer (Lake Shore model 7404-S), but the principles are applicable to other types of VSM. The holder has been tested on powder samples of Co particles on a MgAl2O4 support in both reducing and oxidizing atmospheres. The results show control of gas composition and sample reduction/oxidation. In comparison with conventional sample cups, the in situ holder shows a similar measurement sensitivity but a better repeatability due to the well-controlled gas atmosphere. Moreover, the in situ holder uses a closed gas tubing system such that the active gas only passes by the sample and it is not in contact with the VSM and oven parts. At the outlet, the gas can be collected for analysis and safe handling.
RESUMO
The tailored chemical synthesis of binary and ternary alloy nanoparticles with a uniform elemental composition is presented. Their dual use as magnetic susceptors for induction heating and catalytic agent for steam reforming of methane to produce hydrogen at temperatures near and above 800 °C is demonstrated. The heating and catalytic performance of two chemically synthesized samples of CoNi and CuâCoNi are compared and held against a traditional Ni-based reforming catalyst. The structural, magnetic, and catalytic properties of the samples were characterized by X-ray diffraction, elemental analysis, magnetometry, and reactivity measurements. For induction-heated catalysts, the conversion rate of methane is limited by chemical reactivity, as opposed to the case of traditional externally heated reformers where heat transport limitations are the limiting factor. Catalyst production by the synthetic route allows controlled doping with miniscule concentrations of auxiliary metals.