Yttria modified zirconia (YZ) supported on 5 wt % of Ni-based catalysts promoted with ceria (1−3 wt %) were prepared by the impregnation process to investigate their performance for dry reforming of methane. The reforming reactions, conducted at 700 °C and at atmospheric pressure using a CO 2 /CH 4 /N 2 fixed feed ratio of 3/3/1, with a total flow rate of 70 mL/ min, revealed that the ceria-promoted catalysts (xCe−Ni−YZ; x = 1−3 wt %) enhanced the CH 4 and CO 2 conversions as compared to the reference catalyst (Ni−YZ). A CO 2 conversion of 85% was exhibited by the 3Ce−Ni−YZ catalyst. Despite increased conversions, xCe−Ni−YZ catalysts showed more amounts of carbon deposition as evidenced by the values of TGA, and hence were found to be less stable as compared to the reference Ni−YZ catalyst. The used and fresh catalysts were characterized by BET, H 2 -TPR, XRD, TEM, Raman, TPD, and TGA. TEM images displayed nanoparticle sizes of Ni in the fresh catalysts, while carbon filaments were formed on the spent catalysts. The CO 2 -TPD, H 2 -TPR, and BET results revealed the existence of only weak and moderate basic sites, the increase of total hydrogen consumption, and the surface area values with the addition of the Ce promoter, respectively. The TGA analysis showed that the Ce promoter increased the carbon deposition, while the Raman results indicated the dominance of crystallinity due to the graphitized carbon.

Dry reforming of methane (DRM) has important and positive environmental and industrial impacts, as it consumes two of the top greenhouse gases in order to produce syngas (H2 and CO) and thus hydrogen (H2). The performance of DRM of conversions of CH4 and CO2 was investigated over Ni/ZrO2 catalysts. The catalytic performance of all prepared catalysts for DRM was assessed in a micro-tubular fixed bed reactor under similar reaction conditions (i.e., activation and reaction temperatures at 700 °C, a feed flow rate of 70 mL/min, reaction temperature, and a 440 min reaction time). Various characterization techniques, such as BET, CO2-TPD, TGA, XRD, EDX, and TEM, were employed. The zirconia support was modified with MgO or Y2O3. The yttria-stabilized zirconia catalyst (5Ni15YZr) provided the optimum activity performance of CH4 and CO2 conversions of 56.1 and 64.3%, respectively, at 700 °C and a 70 mL/min flow rate; this catalyst also had the highest basicity. The Ni-based catalyst was promoted with Cs, Ga, and Sr. The Sr-promoted catalyst produced the highest enhancement of activity. The influence of the reaction temperature and the feed flow rate on 5Ni15YZr and 5NiSr15YZr indicated that the activity increased with the increase in the reaction temperature and lower feed flow rate. For 5Ni3Sr15YZr, at a reaction temperature of 800 °C, the CH4 and CO2 conversions were 76.3 and 79.9%, respectively, whereas at 700 °C, the conversions of CH4 and CO2 were 66.6 and 79.6% respectively.

The use of hydrogen as an alternative fuel is an attractive and promising technology as it contributes to the reduction of environmentally harmful gases.