Alumina-Magnesia-Supported Ni for Hydrogen Production via the Dry Reforming of Methane: A Cost-Effective Catalyst System.

5Ni/MgO and 5Ni/γAl 2 O 3 are pronounced in the line of cheap catalyst systems for the dry reforming of methane. However, the lower reducibility of 5Ni/MgO and the significant coke deposition over 5Ni/γAl 2 O 3 limit their applicability as potential DRM catalysts. The mixing capacity of MgO and Al 2 O 3 may overcome these limitations without increasing the catalyst cost. Herein, a 5Ni/xMg(100 - x)Al (x = 0, 20, 30, 60, 70, and 100 wt. %) catalyst system is prepared, investigated, and characterized with X-ray diffraction, surface area and porosity measurements, H 2 -temperature programmed reduction, UV-Vis-IR spectroscopy, Raman spectroscopy, thermogravimetry, and transmission electron microscopy. Upon the addition of 20 wt. % MgO into the Al 2 O 3 support, 5Ni/20Mg80Al is expanded and carries both stable Ni sites (derived through the reduction of NiAl 2 O 4 ) and a variety of CO 2 -interacting species. CH 4 decomposition at Ni sites and the potential oxidation of carbon deposits by CO 2 -interacting species over 5Ni/20Mg80Al results in a higher 61% H 2 -yield (against ~55% H 2 -yield over 5Ni/γAl 2 O 3 ) with an excellent carbon-resistant property. In the major magnesia support system, the 5Ni/60Mg40Al catalyst carries stable Ni sites derived from MgNiO 2 and "strongly interacted NiO-species". The H 2 -yield over the 5Ni/60Mg40Al catalyst moves to 71%, even against a high coke deposition, indicating fine tuning between the carbon formation and diffusion rates. Ni dispersed over magnesia-alumina with weight ratios of 7/3 and 3/7 exhibit good resistance to coke. Weight ratios of 2/8 and 7/3 contain an adequate amount of reducible and CO 2 -interactive species responsible for producing over 60% of H 2 -yield. Weight ratio 6/4 has a proper coke diffusion mechanism in addition to achieving a maximum of 71% H 2 -yield.