Abstract
Ni-based catalysts are prone to agglomeration and carbon deposition at high temperatures. Therefore, the development of Ni-based catalysts with high activities at low temperatures is a very urgent and challenging research topic. Herein, Ni-based nanocatalysts containing Co promoter with mosaic structure were prepared by reduction of NiCoAl-LDHs, and used for CO2 methanation. When the reaction temperature is 250 °C (0.1 MPa, GHSV = 30,000 mL·g−1·h−1), the conversion of CO2 on the NiCo0.5Al-R catalyst reaches 81%. However, under the same test conditions, the conversion of CO2 on the NiAl-R catalyst is only 26%. The low-temperature activity is significantly improved due to Co which can effectively control the size of the Ni particles, so that the catalyst contains more active sites. The CO2-TPD results show that the Co can also regulate the number of moderately basic sites in the catalyst, which is beneficial to increase the amount of CO2 adsorbed. More importantly, the NiCo0.5Al-R catalyst still maintains high catalytic performance after 92 h of continuous reaction. This is due to the confinement effect of the AlOx substrate inhibiting the agglomeration of Ni nanoparticles. The Ni-based catalysts with high performance at low temperature and high stability prepared by the method used have broad industrial application prospects.
Highlights
The large amount of CO2 emission has caused the greenhouse effect to be more obvious, leading to serious environmental problems
The production of CH4 with CO2 as a raw material can help solve the problem of insufficient supply of CH4 in the market, so the CO2 methanation reaction has received increasing attention
Precious metal-based catalysts have excellent low-temperature catalytic activity [15,16], their cost is too high to be suitable for industrial applications
Summary
The large amount of CO2 emission has caused the greenhouse effect to be more obvious, leading to serious environmental problems. Precious metal-based catalysts have excellent low-temperature catalytic activity [15,16], their cost is too high to be suitable for industrial applications. The doped cerium oxide supported Ni-based catalysts can significantly improve the carbon deposition resistance and CO adsorption of the catalysts [34] These methods have made some progress, the traditional supported Ni-based catalysts still have agglomeration and carbon deposition during the reaction process, and their low-temperature catalytic activity still needs to be further improved. By changing the molar ratio of Ni to Fe in the hydrotalcites, the basic sites and particle size of the Ni-based catalysts can be adjusted, thereby improving the CO2 methanation performance of the catalysts [39]. The confinement effect of the AlOx substrate can effectively inhibit the migration and agglomeration of Ni particles during the CO2 methanation reaction, and improve the stability of the catalysts
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