Syngas Production via Methane Dry Reforming over Ceria–Magnesia Mixed Oxide-Supported Nickel Catalysts

Development of high-performance nickel-based catalysts for production of hydrogen and carbon nanotubes from biogas

Selecting a suitable catalyst for implementing the simultaneous production of hydrogen-rich syngas and multi-walled carbon nanotubes through the integration of dry reforming and methane decomposition reactions has recently gained great interests. In this study, a series of bimetallic (NiMo/MgO) and trimetallic (CoNiMo/MgO, FeNiMo/MgO, CoFeMo/MgO) catalysts was prepared and evaluated for a catalytic activity of CH₄ and CO₂ conversions of biogas in a fixed bed reactor at 800 °C and atmospheric pressure. Among the investigated catalysts, the bimetallic NiMo/MgO catalyst showed the outstanding catalytic performance with 86.4% CH₄ conversion and 95.6% CO₂ conversion as well as producing the highest syngas purity of 90.0% with H₂/CO ratio = 1.1. Moreover, the characterization of the synthesized solid products proved that the well-aligned structured morphology, high purity, and excellent textural properties of CNTs were obtained by using NiMo/MgO catalyst. On the other hand, using trimetallic catalysts which have the composition of Co and Fe leads to the severe deactivation. This could be attributed the catalyst oxidation with CO₂ in biogas, resulting in the transformation of metals into large metal oxides. The integrative process with NiMo/MgO catalyst is regarded as a promising pathway, which has a high potential for directly converting biogas into the high value-added products and providing a green approach for managing the enormous amounts of wastes.

Sustainable Synthesis of a Highly Stable and Coke-Free Ni@CeO2 Catalyst for the Efficient Carbon Dioxide Reforming of Methane

A facile and green synthetic strategy is developed in this paper for the construction of an efficient catalyst for the industrially important carbon dioxide reforming of methane, which is also named the dry reforming of methane (DRM). Through controlling the synthetic strategy and Ni content, a high-performance Ni@CeO2 catalyst was successfully fabricated. The catalyst showed superb efficiency for producing the syngas with high and stable conversions at prolonged operating conditions. Incorporating Ni during the ceria (CeO2) crystallization resulted in a more stable structure and smaller nanoparticle (NP) size with a more robust interaction with the support than loading Ni on CeO2 supports by the conventional impregnation method. The H2/CO ratio was almost 1.0, indicating the promising applicability of utilizing the obtained syngas for the Fischer–Tropsch process to produce worthy chemicals. No carbon deposits were observed over the as-synthesized catalyst after operating the DRM reaction for 50.0 h, even at a more coke-favoring temperature (700 ∘C). Owing to the superb resistance to coke and sintering, control of the size of the Ni-NPs, uniform dispersion of the active phase, and potent metal interaction with the support, the synthesized catalyst achieved a magnificent catalytic activity and durability during serving for the DRM reaction for extended operating periods.

Single-Step Flame Aerosol Synthesis of Active and Stable Nanocatalysts for the Dry Reforming of Methane

We introduce a flame-based aerosol process for producing supported non-noble metal nanocatalysts from inexpensive aqueous metal salt solutions, using catalysts for the dry reforming of methane (DRM) as a prototype. A flame-synthesized nickel-doped magnesia (MgO) nanocatalyst (NiMgO-F) was fully physicochemically characterized and tested in a flow reactor system, where it showed stable DRM activity from 500 to 800 °C. A kinetic study was conducted, and apparent activation energies were extracted for the temperature range of 500-650 °C. It was then compared with a Ni-decorated MgO nanopowder prepared by wet impregnation of (1) flame-synthesized MgO (NiMgO-FI) and (2) a commercial MgO nanopowder (NiMgO-CI) and with (3) a NiMgO catalyst prepared by co-precipitation (NiMgO-CP). NiMgO-F showed the highest catalytic activity per mass and per metallic surface area and was stable for continuous H₂ production at 700 °C for 50 h. Incorporation of potential promoters and co-catalysts was also demonstrated, but none showed significant performance improvement. More broadly, nanomaterials produced by this approach could be used as binary or multicomponent catalysts for numerous catalytic processes.