Steam reforming of propane over Ni-K/CeO2-Al2O3 catalyst in fluidized- and fixed-bed reactors under low steam to propane ratio

Fluidized bed was employed to investigate propane steam reforming over Ni-K/CeO2-Al2O3 catalyst. The catalyst was characterized by XRD, SEM, TG/DTA, and N2 adsorption-desorption tests. Effects of promoters, space velocity, temperature, and steam/propane (S/C) ratio on propane conversion, H2 yield, H2/CO ratio, and stability were studied and discussed. The experiments were carried out under conditions which favored coke formation. The reaction in the fluidized bed was compared with the reaction in a conventional fixed bed reactor. Obtained results indicated that fluidization and continuous circulation of catalyst induced back-mixing phenomena, increasing contact rate between catalysts and feed, uniform distribution of temperature, and steam concentration. As a result, higher conversion, H2 yield, and significant suppression of coke deposition were observed in the fluidized bed at all of the experimental conditions. The fluidized bed catalyst also exhibited good regenerability by restoring its initial catalytic activity after one h of regeneration in air. It was shown that fluidization could compensate for the lack of water and enhance coke gasification. At S/C=3, the catalytic performance in both reactors was almost stable. With decreasing S/C to 2.5, the activity in the fixed bed decreased rapidly. While the stability was more pronounced in the fluidized bed. At S/C=1.5, the catalyst at both reactors deactivated fast due to the lower H/C ratio, massive coke formation, and poor fluidization.