| dc.description.abstract | In recent years, nonthermal plasma has been utilized as a novel technique to enhance the activity of catalyst. The study applied this novel technique to the preparation of the catalyst for methanol synthesis Such study has yet reported so far. The main objective of this study is to investigate the feasibility of using nonthermal plasma to modify the performance of methanol synthesis catalyst. In terms of methanol synthesis by catalysis, the catalyst is generally prepared via coprecipitation, and consists of precipitation, washing, filtration, drying, calcination and reduction. In this study, plasma treatment can be applied before/after calcination or used to replace calcinations. A variety of catalysts have been experimentally tested in this study, i.e., commercial, self-made (without plasma treatment), O2-plasma-treated, and H2-plasma-treated catalysts. The experimental results indicate the self-made catalyst could achieve better performance than the commercial one. On the other hand, the treatment of O2 plasma (before calcination) could shift the optimum temperature for methanol synthesis from 255oC to 235oC and increase the selectivity of MeOH at the same time. As for the H2-plasma-treated (replace calcination) catalyst, although the best CO conversion rate obtained in this study is as high as 97%, the main products are CO2 and CH4 instead of the desired product, MeOH. As a further study on applying different plasma treatments and processes, it reveals that the selectivity and the yield of MeOH from H2-plasma-treated catalyst before calcinations and O2-plasma-treated catalyst after calcinations are lower than that of self-made catalysts. That is to say, the selectivity and yield of MeOH from H2-plasma-treated catalyst before calcinations and O2-plasma-treated catalyst after calcinations are better than that of self-made catalysts. To get insights into the influence of plasma treatment on the physical and chemical properties of the catalyst, the measurements of XRD, ICP and surface area are also conducted in this study. The results indicate that the plasma treatment could decompose the precursors of the active components. Moreover, after plasma treatment, larger surface area and smaller CuO grain size could be achieved as well. Besides, it is worth noticing that the energy required for the treatment of Cu/ZnO/Al2O3 catalyst is only 11 kJ/g-cat, which is economically competitive. In conclusion, it has been demonstrated in this study that the plasma treatment could alter the physical and chemical properties of the catalyst. However, the alteration is not always beneficial for methanol synthesis. Therefore, one should be careful in selecting the background gas of plasma so that the plasma treatment process is beneficial to catalyst performance.
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