Enhanced catalytic activity of Ni-Mo2C/La2O3-ZrO2 bifunctional catalyst for dry reforming of methane

摘要

A series of Ni-modified Mo2C catalysts with La2O3-stabilized ZrO2 supports were synthesized via template method coupled with incipient wetness impregnation and temperature-programmed carbonization. The catalyst was tested in dry reforming of methane (DRM) reaction at the temperature range from 973 to 1173 K in a fixed-bed quartz reactor under atmospheric pressure. XRD, Raman, BET, H-2-TPD, SEM, EDS and TEM were conducted to characterize the phase constitution, the pore structure, the morphology and the crystal structure of the catalysts. N-Mo2C nanoparticles of similar to 3 nm diameter were obtained for these catalysts, and the La2O3-ZrO2 supports exhibited a cubic lattice structure with a sheet shape, which is believed to contain an abundant of oxygen vacancies. And the synergistic interaction between the oxygen vacancy in La-Zr-O solid solution and the Ni-Mo2C particles could decrease the apparent activation energy of CO2. Both of them are beneficial for accelerating DRM reaction. CH4 conversion of the best specimen catalyst reaches 94% at 1173 K, and the catalyst maintains its stability after 100-h reaction. The superior catalytic activity of NMLZ-7.5 is attributed to the improved BET surface area (33.2 m(2)/g), smaller crystallites, grain boundaries and oxidation-carbonization cycle of Ni-Mo2C.