Dry reforming of greenhouse gases CH4/CO2 over MgO-promoted Ni-Co/Al2O3-ZrO2 nanocatalyst: effect of MgO addition via sol-gel method on catalytic properties and hydrogen yield

Sol-gel method was employed to prepare Ni-Co/Al2O3-MgO-ZrO2 nanocatalyst with various loadings of MgO (5, 10 and 25 wt%) for dry reforming of methane. The physiochemical properties of nanocatalysts were characterized by XRD, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), BET and fourier transform infrared spectroscopy (FTIR) analysis. Evaluation of catalytic performance was conducted in atmospheric pressure, stoichiometric feed ratio, GHSV of 24 l/g(cat) h and temperature range from 550 to 850 A degrees C. XRD patterns represented that as MgO content increases, the amorphous behavior slightly intensifies and also dispersion of active phase improves which probably caused by strong metal-support interaction. Furthermore, FESEM analysis confirmed that all of prepared samples are nano scale. EDX results besides verifying the declared claim about the dispersion of samples proved the presence and detected the position of the various elements. In addition, based on the FESEM analysis, narrow particle size distribution, uniform morphology and dispersion without agglomeration were found for Ni-Co/Al2O3-MgO-ZrO2 with 25 wt% MgO. Moreover, smallest average particle size 11.6 nm (close to the critical size for Ni-Co catalyst to avoid carbon formation) was obtained for this nanocatalyst. Also, according to the BET analysis, MgO rich nanocatalyst represented the higher surface area than the other ones. Based on the excellent characterizations, Ni-Co/Al2O3-MgO-ZrO2 with 25 wt% MgO exhibited the best products yield through all of the investigated temperature e.g. H-2 = 96.9 % and CO = 97.1 % at 850 A degrees C. Furthermore, this nanocatalyst demonstrated the stable yield with H-2/CO close to unit during 1,440 min stability test.