Papers by Keyword: Metal Loading

Abstract: Utilization of CO₂ as a carbon source to produce valuable chemicals is one of the important ways to reduce the global warming caused by increasing CO₂ in the atmosphere. Supported metal catalysts are crucial to produce clean and renewable fuels and chemicals from the stable CO₂ molecules. The catalytic conversion of CO₂ into methanol is recently under increased scrutiny as an opportunity to be used as a low-cost carbon source. Therefore, a series of the bimetallic Cu/ZnO-based catalyst supported by SBA-15 were synthesized via an impregnation technique with different total metal loading and tested in the catalytic hydrogenation of CO₂ to methanol. The morphological and textural properties of the synthesized catalysts were determined by transmission electron microscopy (TEM), temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO), and N2-adsorption. The CO₂ hydrogenation reaction was performed in a microactivity fixed-bed system at 250^oC, 2.25 MPa, and H₂/CO₂ ratio of 3. Experimental results showed that the catalytic structure and performance were strongly affected by the loading of the active site. Where, the catalytic activity, the methanol selectivity as well as the space-time yield increased with increasing the metal loading until it reaches the maximum values at a metal loading of 15 wt% while further addition of metal inhibits the catalytic performance. The higher catalytic activity of 14% and methanol selectivity of 92% was obtained over a Cu/ZnO-SBA-15 catalyst with a total bimetallic loading of 15 wt%. The excellent performance of 15 wt% Cu/ZnO-SBA-15 catalyst is attributed to the presence of well dispersed active sites with small particle size, higher Cu surface area, and lower catalytic reducibility.

Abstract: In this work, we prepared porous graphite nanofibers (PCNFs) from herringbone-type graphite nanofibers, and nano-sized transition metals such as copper metal, were loaded on the PCNFs by a metal electroplating in order to prepare novel catalysts for the control of toxic gases, such as hydrogen chloride. From experimental results, PCNFs had around 2000 m2/g of a specific surface area, and it was decreased slightly after metal loading. In case of metal content, we could control them from less 3 to over 30 wt% by means of the plating time and current density applied. After the metal loading, all samples having transition metal nanoclusters showed higher efficiency of HCl removal than that of samples without metals. However we also found that some samples having excessive metal content showed a decrease in the efficiency of HCl removal. This result meant that one of key technologies was both to find optimal metal content and to remain high specific surface area of substrates.