Carbon Dioxide Reforming of Methane over Nickel Catalyst Supported on MgO(111) Nanosheets

Surface basicity controls C-C coupling rates during carbon dioxide-assisted methane coupling over bifunctional Ca/ZnO catalysts

Carbon dioxide-assisted coupling of methane offers an approach to chemically upgrade two greenhouse gases and components of natural gas to produce ethylene and syngas. Prior research on this reaction has concentrated efforts on catalyst discovery, which has indicated that composites comprised of both reducible and basic oxides are especially promising. There is a need for detailed characterization of these bifunctional oxide systems to provide a more fundamental understanding of the active sites and their roles in the reaction. We studied the dependence of physical and electronic properties of Ca-modified ZnO materials on Ca content via X-ray photoelectron and absorption spectroscopies, electron microscopy, and infrared spectroscopic temperature-programmed desorption (IR-TPD). It was found that introduction of only 0.6 mol% Ca onto a ZnO surface is necessary to induce significant improvement in the catalytic production of C₂ species: C₂ selectivity increases from 5% on un-modified ZnO to 58%, at similar conversions. Evidence presented shows that this selectivity increase results from the formation of an interface between the basic CaO and reducible ZnO phases. The basicity of these interface sites correlates directly with catalytic activity over a wide composition range, and this relationship indicates that moderate CO₂ adsorption strength is optimal for CH₄ coupling. These results demonstrate, for the first time to our knowledge, a volcano-type relationship between CO₂-assisted CH₄ coupling activity and catalyst surface basicity, which can inform further catalyst development.

Understanding the role of surface basic sites of catalysts in CO2 activation in dry reforming of methane: a short review

Surface oxygen basic sites are vital to the CO₂ activation in dry reforming of methane.

Influence of Nature Support on Methane and CO2 Conversion in a Dry Reforming Reaction over Nickel-Supported Catalysts

A promising method to reduce global warming has been methane reforming with CO2, as it combines two greenhouse gases to obtain useful products. In this study, Ni-supported catalysts were synthesized using the wet impregnation method to obtain 5%Ni/Al2O3(SA-5239), 5%Ni/Al2O3(SA-6175), 5%Ni/SiO2, 5%Ni/MCM41, and 5%Ni/SBA15. The catalysts were tested in dry reforming of methane at 700 °C, 1 atm, and a space velocity of 39,000 mL/gcat h, to study the interaction of Ni with the supports, and evaluation was based on CH4 and CO2 conversions. 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2 gave the highest conversion of CH4 (78 and 75%, respectively) and CO2 (84 and 82%, respectively). The catalysts were characterized by some techniques. Ni phases were identified by X-ray diffraction patterns. Brunauer-Emmett-Teller analysis showed different surface areas of the catalysts with the least being 4 m2/g and the highest 668 m2/g belonging to 5%Ni/Al2O3(SA-5239) and 5%Ni/SBA15, respectively. The reduction profiles revealed weak NiO-supports interaction for 5%Ni/Al2O3(SA-5239), 5%Ni/MCM41, and 5%Ni/SBA15; while strong interaction was observed in 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2. The 5%Ni/Al2O3(SA-6175) and 5%Ni/SiO2 were close with respect to performance; however, the former had a higher amount of carbon deposit, which is mostly graphitic, according to the conducted thermal analysis. Carbon deposits on 5%Ni/SiO2 were mainly atomic in nature.

Atomic Layer Deposition for Preparation of Highly Efficient Catalysts for Dry Reforming of Methane

In this article, the structural and chemical properties of heterogeneous catalysts prepared by atomic layer deposition (ALD) are discussed. Oxide shells can be deposited on metal particles, forming shell/core type catalysts, while metal nanoparticles are incorporated into the deep inner parts of mesoporous supporting materials using ALD. Both structures were used as catalysts for the dry reforming of methane (DRM) reaction, which converts CO2 and CH4 into CO and H2. These ALD-prepared catalysts are not only highly initially active for the DRM reaction but are also stable for long-term operation. The origins of the high catalytic activity and stability of the ALD-prepared catalysts are thoroughly discussed.

Sulfur-resistant and regenerable Ni/Co spinel-based catalysts for methane dry reforming

High-perfection Ni/Co spinel microcrystalline catalysts with extensive faceting show high turnover frequencies in methane dry reforming and good sulfur tolerance.