| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 105 === In this study, CO2 methanation performance was investigated using Ni/Al2O3, Ru/Al2O3 and Ru-Ni/Al2O3 as catalysts under atmospheric pressure condition. For Ni catalyst, the loading was varied from 5wt% to 20%wt% while the loading for Ru was varied from 1wt% to 5wt%. For bimetallic catalysts, loadings with 1wt%Ru-10wt%Ni and 1wt%Ru-15wt%Ni were tested. The reactant was composed of 9.1% CO2, 45.45% H2, and 45.45% N2. Effect of metal loadings on CO2 conversion, H2 efficiency, CH4 yield, and CO yield were measured and used to characterize the CO2 methanation performance. For the reaction temperature ranged from 250°C to 550°C with step size of 50°C and reactant flow rate of 55 sccm, it was found that the CO2 methanation performance can be enhanced by increasing Ni and Ru loadings. The optimum reaction temperature was found to be 400°C for all catalysts studied. At this temperature, maximum values of CO2 conversion, H2 efficiency, CH4 yield and lowest CO yield can be obtained. The experimental results showed that the effect on CO2 methanation performance was insignificant when gas hourly space velocity was varied in the range of 2917 h-1 to 8753 h-1. Moreover, it was found that the CO2 methanation performance at low temperature can be enhanced greatly using bimetallic Ru-Ni as compared with the corresponding monometallic Ru or Ni catalyst. Under ascending-descending temperature change between 250°C and 550°C for three continuous cycles, good thermal stability of Ru-Ni/Al2O3 catalyst can be resulted. The CO2 conversion was found to decrease from 80.51% to 76.66% after the cyclic test for 450°C.
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