Abstract
Hydrogen production through methane dry reforming holds the promise of lowering greenhouse gases, that is CO2 and CH4, concentrations. Herein, Ca-, Cr-, Ga- and Gd-promoted lanthana-zirconia-supported Ni catalysts are investigated and characterized by X-ray diffraction, Raman, infrared and UV-vis spectroscopy, CH4-temperature programmed surface reaction and cyclic reduction-desorption experiment. All promoted catalyst systems had high and constant hydrogen yield (>70%) due to pronounced reoxidation capacity of reduced 'NiO species strongly interacted with support' through oxygen replenishment by CO2. The presence of mixed oxide and regeneration of reduced catalyst up to optimum level through oxygen replenishment by CO2 in Gd, as well as Cr-promoted catalyst, outperformed (80% initially) than other promotors, Ca and Ga. In the long run (440 min to 33 h), Cr-promoted catalyst system performed better than Gd-promoted catalyst system as H-2 yield remained constant similar to 79% due to the smallest energy gap between valance and conduction band, Ni-Cr interaction species for wide range CH4 decomposition and chromate species for profound carbon deposit oxidation.