H2 production via sorption-enhanced water-gas-shift using bimetallic catalysts doped CaO-Ca12Al14O33: Experiment and density functional theory study

Herein, a series of monometallic and bimetallic (Fe, Co, Ni, Cu, Zn) doped CaO-Ca12Al14O33 materials were prepared and used for H2 production from sorption-enhanced water-gas-shift (SEWGS). The synergetic effect of bi- transition metal elements doping on CaO-Ca12Al14O33 for H2 production via SEWGS was investigated through the experimental and density functional theory calculation. The results indicate that Fe/Ni-doped CaOCa12Al14O33 exhibits the highest H2 production activity among these bifunctional materials. The synergetic promoting effect of the Fe/Ni doping on CaO/Ca12Al14O33 contributes to the excellent and stable H2 production performance. The initial CO conversion and H2 concentration are as high as 98.8% and 93.4% for the optimal Fe/ Ni-doped CaO-Ca12Al14O33 at the Fe/Ni molar ratio of 1:1, respectively, which retain 95.7% and 89.6% after 20 cycles. The mechanism of Fe/Ni-doped CaO/Ca12Al14O33 for H2 production via SEWGS is determined. The Fe/Ni interaction boosts the electron transfer from Fe to Ni species, thereby promoting the reductivity of the Fe/Nidoped CaO/Ca12Al14O33. In addition, the Fe/Ni interaction facilitates the O-H bond cleavage to generate H2 and inhibits the undesirable CH4 by-product formation. Moreover, the interaction between Fe and Ni species is beneficial for the formation of oxygen vacancy. Therefore, the catalytic activity and in-situ CO2 removal capacity are enhanced by using Fe/Ni-doped CaO-Ca12Al14O33 to produce more H2. These significantly enhance the potential of the Fe/Ni-doped CaO-Ca12Al14O33 for efficient H2 production via SEWGS.