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Bimetallic Ni@Ru nanoparticles with Ni core and Ru shell supported on SiO2 were prepared by impregnation method using a perovskite-type oxide of LaRuxNi1−xO3 as the precursor and used as catalysts for CO methanation. The catalysts were characterized by using BET, XRD, H2-TPR, HRTEM + EDX, ICP, H2 chemisorption, XPS and TGA techniques. By reducing the catalysts with hydrogen, bimetallic nanoparticles with the structure of nickel shell and ruthenium core of Ru@Ni supported on SiO2 doped with La2O3 were made, and the Ru would migrate to the surface of the Ni-Ru cluster forming the ruthenium shell and nickel core of Ni@Ru under CO atmosphere. The supported bimetal catalysts with core–shell structure by doping small amount of noble metal exhibited very good catalytic performance for CO methanation, especially showed excellent resistance to carbon deposition and metal sintering, while the monometallic catalyst of nickel showed inferior catalytic performance.

The critical problem for CO methanation catalysts to produce synthetic natural gas is deactivation due to carbon deposition and/or sintering of the active components. It was reported that Ni/La2O3 has better resistance to sintering and can eliminate the carbon deposited via lanthanum containing compound. However, the lanthanum oxide has low surface area, mechanical strength and stability. To overcome this problem, a new scheme has been proposed in this study by supporting the perovskite-type oxide of LaNiO3 on SiO2. Nickel and lanthanum ions are evenly dispersed at atomic level in the nanocrystallites of LaNiO3, after reduction highly dispersed small Ni nanoparticles were supported on La2O3 which spread on SiO2. Thus, Ni/La2O3 was loaded on SiO2. The catalysts were characterized by means of BET, XRD, HRTEM + EDX, H2 chemisorption, ICP, and TGA techniques, and their catalytic performances were measured for CO methanation from syngas to generate CH4. The prepared catalyst derived from LaNiO3/SiO2 showed very good catalytic performance, especially showed very high resistance towards carbon deposition and nickel sintering. The NiO-La2O3/SiO2 prepared by common incipient-wetness impregnation method was investigated for comparison. This method can be extended for loading other catalysts, for that a lot of metallic ions can be acted as the ions of perovskite-type oxides.

Carbon deposition and sintering of active components such as nano particles are great challenges for Ni-based catalysts for CO methanation to generate synthetic natural gas from syngas. Facing the challenges, bimetallic catalysts with different Fe content derived from layered double hydroxide containing Ni, Fe, Mg, Al elements were prepared by co-precipitation method. Nanoparticles of Ni-Fe alloy were supported on mixed oxides of aluminium and magnesium after calcination and reduction. The catalysts were characterized by Brunner-Emmett-Teller (BET), X-ray diffraction, hydrogen temperature programmed reduction, inductively coupled plasma, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric techniques, and their catalytic activity for CO methanation was investigated. The results show that the Ni-Fe alloy catalysts exhibit better catalytic performance than monometallic catalysts except for the Ni4Fe-red catalyst. The Ni2Fe-red catalyst shows the highest CO conversion (100% at 260–350 °C), as well as the highest CH4 selectivity (over 95% at 280–350 °C), owing to the formation of Ni-Fe alloy. In stability test, the Ni2Fe-red catalyst exhibits great improvement in both anti-sintering and resistance to carbon formation compared with the Ni0Fe-red catalyst. The strong interaction between Ni and Fe element in alloy and surface distribution of Fe element not only inhibits the sintering of nanoparticles but restrains the formation of Ni clusters.