Carbon dioxide reforming of methane with supported rhodium

A review of dry (CO2) reforming of methane over noble metal catalysts

Dry (CO2) reforming of methane (DRM) is a well-studied reaction that is of both scientific and industrial importance. This reaction produces syngas that can be used to produce a wide range of products, such as higher alkanes and oxygenates by means of Fischer-Tropsch synthesis. DRM is inevitably accompanied by deactivation due to carbon deposition. DRM is also a highly endothermic reaction and requires operating temperatures of 800-1000 °C to attain high equilibrium conversion of CH4 and CO2 to H2 and CO and to minimize the thermodynamic driving force for carbon deposition. The most widely used catalysts for DRM are based on Ni. However, many of these catalysts undergo severe deactivation due to carbon deposition. Noble metals have also been studied and are typically found to be much more resistant to carbon deposition than Ni catalysts, but are generally uneconomical. Noble metals can also be used to promote the Ni catalysts in order to increase their resistance to deactivation. In order to design catalysts that minimize deactivation, it is necessary to understand the elementary steps involved in the activation and conversion of CH4 and CO2. This review will cover DRM literature for catalysts based on Rh, Ru, Pt, and Pd metals. This includes the effect of these noble metals on the kinetics, mechanism and deactivation of these catalysts.

Solar thermal catalytic reforming of natural gas: a review on chemistry, catalysis and system design

Solar thermal catalytic reforming of natural gas is a promising route to increase the efficiency of fossil fuels utilization.

Highly coke-resistant ni nanoparticle catalysts with minimal sintering in dry reforming of methane

Nickel catalysts are typically used for hydrogen production by reforming reactions. Reforming methane with carbon dioxide, called dry reforming of methane (DRM), is a good way to produce hydrogen or syngas (a mixture of hydrogen and carbon monoxide) from two notable greenhouse gases. However, Ni catalysts used for DRM suffer from severe coke deposition. It has been known that small Ni nanoparticles are advantageous to reduce coke formation, but the high reaction temperature of DRM (800 °C) inevitably induces aggregation of the nanoparticles, leading to severe coke formation and degraded activity. Here, we develop highly coke-resistant Ni catalysts by immobilizing premade Ni nanoparticles of 5.2 nm in size onto functionalized silica supports, and then coating the Ni/SiO2 catalyst with silica overlayers. The silica overlayers enable the transfer of reactants and products while preventing aggregation of the Ni nanoparticles. The silica-coated Ni catalysts operate stably for 170 h without any degradation in activity. No carbon deposition was observed by temperature programmed oxidation (TPO), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. The Ni catalysts without silica coating show severe sintering after DRM reaction, and the formation of filamentous carbon was observed. The coke-resistant Ni catalyst is potentially useful in various hydrocarbon transformations.

The role of carbonaceous deposits in the activity and stability of Ni-based catalysts applied in the dry reforming of methane

Highly stable Ni catalysts with varying Ni contents up to 50 mol% originating from hydrotalcite-like precursors were applied in the dry reforming of methane at 800 and 900 °C.

Significant roles of mesostructure and basic modifier for ordered mesoporous Ni/CaO–Al2O3 catalyst towards CO2 reforming of CH4

The significant roles of mesostructure and basic modifier in improving the catalytic performance of dry reforming were investigated.

High-pressure scanning tunneling microscopy: tip reactions

Scanning tunneling microscopy (STM) is an ideal tool to image conducting and semiconducting surfaces with atomic resolution. The technique provides high-resolution images in vacuum or even high-pressure environments. Since STM can be operated at elevated pressures and temperatures, images can be collected in situ under catalytic conditions. In this work, we demonstrate that artifacts can be observed when imaging in situ since reactions can occur on the tip, and care should be taken when analyzing the data obtained.