Abstract
The Paris Agreement requires the world to put the best efforts to reduce CO2 emissions, due to the global warming problems. As a promising technology corresponding to this greenhouse gas treatment, the CO2 methanation process a.k.a power to gas (PtoG), which catalytically converts CO2 into methane, has been in the limelight. To develop an efficient catalytic process, it is necessary to design a low-cost and high-efficiency catalyst for high CO2 conversion and CH4 selectivity. In this study, we have developed Ni/γ-Al2O3 catalysts by the one-step melt-infiltration method, where both aging and calcination are done in one pot. For enhancement of the catalytic activity and selectivity, sufficient Ni content (>25 wt %) and a high dispersion (<10 nm) are simultaneously required. Thus, the aging conditions of the melt-infiltration methods, e.g., time and temperature, were optimized for the high dispersion with sufficient Ni content (15–50 wt %). The catalytic performance tests were carried out under atmospheric pressure, 275 to 400 °C and gas hourly velocity (GHSV) = 25,000 h−1. And the various characteristic analyses (Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), H2-chemisorption, temperature programmed reduction (TPR), etc.) were performed to confirm the effects on the catalytic performance. As a result, based on the experiments and the characterization data, the 30 wt %-Ni catalyst (Ni particles size = 11 nm) showed the best CO2 conversion at 300 °C and the 20 wt % one having the highest Ni dispersion (Ni particles size = 8.8 nm), which showed the best intrinsic reaction rate and CH4 selectivity in the entire temperature range.
Highlights
As part of the effort to ameliorate the problem of global warming, the share of renewable energy sources used to meet primary energy demands across the world reached around 10% in 2017 [1]
Development, Business (R&BD) activities related to the power-to-gas technologies, in which excess electricity is converted into gas energy via electrolysis and methanation, are being carried out, to enhance the utilization of renewable energy sources, and the reliability of the power grid [3,4,5,6,7]
Nickel-based catalysts with high metal dispersion and high nickel loading were prepared by the one-step melt-infiltration method
Summary
The increased amount of electricity generated from the increase in renewable energy in the power grid introduces issues of electricity infrastructure flexibility [2]. In countries, such as Germany and Denmark, where a large fraction of electricity is generated from renewable energy sources, various Research &. Development, Business (R&BD) activities related to the power-to-gas technologies, in which excess electricity is converted into gas energy (hydrogen and/or methane) via electrolysis and methanation, are being carried out, to enhance the utilization of renewable energy sources, and the reliability of the power grid [3,4,5,6,7]. Sabatier reaction) isand severely exothermic, and◦ C, proceeds at 180–350 °C, bar.
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