NiAlFe catalysts based on the hydrotalcite-like precursor were prepared and the catalysts exhibit excellent low temperature catalytic activity for CO2 methanation. CO2 conversion over the NiAlFe0.3 catalyst is nearly 80 % under the condition of T = 225 °C, P = 1 atm, and WHSV = 24000 mL/(g∙h). With the increase in the substitution of Fe for Al, the hydrotalcite-like structure of the catalyst precursor is gradually destroyed; the reducibility of NiO component is promoted; the amount of surface basic site decreases. There is a strong electronic push–pull effect between NiO and Al2O3 in the calcined catalyst, and the electronic effect is weakened with the introduction of Fe because Fe3+ shares the responsibility of Ni2+ for donating electron to Al3+. In the reduced catalysts, the Ni3Fe alloy was formed and the electrons are pushed from Ni0 to Fe0. With the increase in the Fe amount, the number of surface Ni atom decreases, while the intrinsic activity of Ni active site enhances. The number and intrinsic activity of Ni site are the main two factors determining the CO2 methanation activity at low temperature. Moreover, the substitution of Al3+ by Fe3+ is beneficial for the stability of the catalysts by inhibiting the agglomeration of catalyst particle.
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