Effect of synthesis solution pH of Co/γ-Al2O3 catalyst on its catalytic properties for methane conversion to syngas

The cobalt nanoparticles over γ-Al2O3 support were prepared via chemical reduction of CoCl2·6H2O using NaBH4 with various values of pH in the range of 11.92-13.80. Synthesized catalysts were studied through X-ray diffraction (XRD), N2 adsorption/desorption (BET), H2-temperature programmed reduction (H2-TPR), H2-chemisorption, O2 pulse titration and temperature programmed oxidation (TPO) methods. Obtained results exhibited the synthesis solution pH showed a significant influence on the activity and selectivity in partial oxidation of methane reaction. The methane conversion, CO selectivity and H2 yield were enhanced by increasing of the synthesis solution pH. Compared to other catalysts, the catalyst that synthesized at pH of 13.80, showed a superior ability in syngas production with a H2/CO ratio of near 2 and also a proper stability against deactivation during the partial oxidation of methane.