Preparation of a NiO-CaO/Al2O3 sorption complex catalyst by hydrothermal precipitation method and its application in ReSER process

A NiO-CaO/Al2O3 sorption complex catalyst with highly catalytic activity was prepared and applied in reactive sorption enhanced reforming (ReSER) process. A layer-structured double hydroxide precursor (NiAl-LDHs) was prepared by hydrothermal precipitation method. The precursor was then calcined to NiO-CaO/Al2O3 composite catalyst hd-cat. Another NiO-CaO/Al2O3 composite catalyst ci-cat was prepared by impregnation method for comparison. The catalyst hd-cat was observed to have a surface area of 134.4 m2·g-1 by BET testing and a Ni dispersion of 9.25% in H2-TPD testing, which were 3.8 times and 1.3 times as much as those of ci-cat, respectively. TGA testing indicated that the sorption capacity and the sorption rate of hd-cat were 1.8 times and 2.7 times as much as those of ci-cat. The catalysts were evaluated in ReSER process in a fixed-bed reactor system at 0.1 MPa and 600℃ with a H2O/CH4 molar ratio of 4:1. The hydrogen production performances under different volumetric space velocities were studied. A H2 concentration of 94.4% and a CH4 conversion of 98.4% were achieved at a space velocity of 2376 h-1 using the hd-cat catalyst. And during 10 times reaction-regeneration cycles, both H2 concentration and CH4 conversion exceeded 90%. However, the ci-cat catalyst lost its activity under a space velocity of 1188 h-1. These results demonstrate that composite catalyst prepared by hydrothermal precipitation method can perform well under high space velocity in ReSER process.