Novel highly efficient Ni-based mesoporous alumina-silica supported catalysts for methane dry reforming: Influence of nickel loading

Abstract

In this study, the dry reforming of methane (DRM) was examined over the Ni/Al2O3-SiO2 catalysts with various nickel contents for the syngas production. The mesoporous nanocrystalline aluminosilicate with a high surface area (180.87 m2. g−1) was utilized as support for preparing the nickel-based catalysts by the wet impregnation method. The XRD, BET, H2-TPR, TPO, and FESEM analyses were performed to characterized the calcined catalysts. The obtained results indicated that the catalyst efficiency was enhanced by increasing the nickel loading values from 5 to 15 wt%, while the sample with 20 wt% Ni showed a lower efficiency compared to the 15 wt% Ni catalyst. The catalyst with 15 wt% Ni loading showed the best activity (XCO2 = 79%, XCH4 = 74.5%) and stability (activity drop for CH4 ≈ 2.7% and CO2 ≈ 0.3%) at 700 °C for 5 h. Also, the effects of the operational conditions, such as GHSV, CH4/CO2 ratio, long-term stability, reduction and calcination temperatures were studied. As GHSV changed from 12000 to 30000 ml/h.gcat, both conversions were declined. Also, the CO2 conversion was increased and the CH4 conversion was decreased by increasing the feed molar ratio (CH4: CO2) from 0.5 to 2. A constant syngas generation was obtained in long-term stability test of the reduced catalyst, which had no variation in activity during 10 h of reaction. In addition, there was no significant difference in results when the calcination (550, 650, and 750 °C) and reduction temperatures (600, 700, and 800 °C) were varied.