The increase in atmospheric carbon dioxide is linked to climate changes; hence there is an urgent need to reduce the accumulation of CO2 in the atmosphere. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers offers a way to mitigate the increasing CO2 buildup. This review covers six important CO2 transformations namely: chemical transformations, photochemical reductions, chemical and electrochemical reductions, biological conversions, reforming and inorganic transformations. Furthermore, the vast research area of carbon capture and storage is reviewed briefly. This review is intended as an introduction to CO2, its synthetic reactions and their possible role in future CO2 mitigation schemes that has to match the scale of man-made CO2 in the atmosphere, which rapidly approaches 1 teraton.

The teraton challenge. A review of fixation and transformation of carbon dioxide

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.

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

Although technological practice should minimize environmental impact, this is not always economically feasible. During the past decade, for example, there has been increasing global concern over th...

CO2 Reforming of CH4

Hydrogen production reactions from carbon feedstocks: fossil fuels and biomass.

Hydrogen production by methane decomposition: A review

Nonequilibrium Oxidative Conversion of Methane to CO and H2 with High Selectivity and Productivity over Ni/Al2O3 at Low Temperatures

Catalytic partial oxidation of methane over NiO-CaO (with or without its prereduction by H2) at low temperatures (⩽ 973 K) under non-equilibrium conditions yields syngas (H2/CO ratio ≈ 2.0) with high conversion/selectivity and extremely high productivity. If required, the H2/CO ratio can be increased by adding water vapour to the feed. Product selectivity is controlled by the process kinetics and also the reaction path is different from that observed for the high-temperature non-catalytic and catalytic processes operating at equilibrium.

Low temperature oxidative conversion of methane to syngas over NiO-CaO catalyst

By simultaneous reactions of methane with CO2 and O2 over NiO-CaO catalyst under certain reaction conditions, it is possible to convert methane into syngas with low H2/CO ratio (1 <H2/CO <2) at above 95% conversion, with 100% CO selectivity and above 90% H2 selectivity and also with very high CO productivity without catalyst deactivation due to coking for a long period, in a most energy efficient and safe manner, requiring little or no external energy.

Energy efficient methane-to-syngas conversion with low H2/CO ratio by simultaneous catalytic reactions of methane with carbon dioxide and oxygen

Steam reforming, CO2 reforming, and simultaneous steam and CO2 reforming of methane to CO and H2 over NiO−CaO catalyst (without any prereduction treatment) at different temperatures (700−850 °C) and space velocities (5000−70 000 cm3·g-1·h-1) are investigated. The catalyst is characterized by XRD, XPS, and temperature-programmed reduction (TPR). The catalyst showed high activity/selectivity in both the steam and CO2 reforming reactions and the simultaneous steam and CO2 reforming. In the CO2 reforming, the coke deposition on the catalyst is found to be very fast. However, when the CO2 reforming is carried out simultaneously with the steam reforming, the coke deposition on the catalyst is drastically reduced. By the simultaneous CO2 and steam reforming (at ≥800 °C and space velocity of about 20 000−30 000 cm3·g-1·h-1), methane can be converted almost completely to syngas with 100% selectivity for both CO and H2. The H2/CO ratio in products can be varied between 1.5 and 2.5 quite conveniently by manipulating...

Simultaneous Carbon Dioxide and Steam Reforming of Methane to Syngas over NiO−CaO Catalyst

NiO-Alkaline Earth Oxide Catalysts for Oxidative Methane-to-Syngas Conversion: Influence of Alkaline Earth Oxide on the Surface Properties and Temperature-Programmed Reduction/Reaction by H2and Methane

Amarjeet M. Rajput

Papers

Nonequilibrium Oxidative Conversion of Methane to CO and H2 with High Selectivity and Productivity over Ni/Al2O3 at Low Temperatures

Low temperature oxidative conversion of methane to syngas over NiO-CaO catalyst

Energy efficient methane-to-syngas conversion with low H2/CO ratio by simultaneous catalytic reactions of methane with carbon dioxide and oxygen

Simultaneous Carbon Dioxide and Steam Reforming of Methane to Syngas over NiO−CaO Catalyst

NiO-Alkaline Earth Oxide Catalysts for Oxidative Methane-to-Syngas Conversion: Influence of Alkaline Earth Oxide on the Surface Properties and Temperature-Programmed Reduction/Reaction by H2and Methane