Reverse water gas shift reaction

The catalytic reduction of CO 2 into value-added products has reverse water gas shift reaction considered a compelling solution for alleviating global warming and energy crises. The reverse water gas shift RWGS reaction plays a pivotal role among the various CO 2 utilization approaches, due to the fact that it produces syngas, the building block of numerous conversion processes. Although a lot of work has been carried out towards the development of a RWGS process, ranging from efficient catalytic systems to reactor units, and even pilot scale processes, reverse water gas shift reaction, there is still a lack of understanding of the fundamental phenomena that take place at the various levels and scales of the process.

The Reverse Water-Gas Shift Reaction RWGS reaction was discovered in the 19th century as a method of producing water from carbon dioxide and hydrogen , with carbon monoxide as a side product. Alternatively, it can be used with water electrolysis to generate carbon monoxide and oxygen. The oxygen is used for breathing or as oxidizer, while the carbon monoxide can be used as a moderate specific-impulse fuel with oxygen as the oxidizer or as a feedstock to generate higher hydrocarbons see Fischer-Tropsch reaction Whether one would use the RWGS reaction or the Bosch reaction depends largely on whether carbon monoxide or elemental carbon is the preferred by-product. The reactor itself is very similar to a Sabatier unit; a simple steel pipe filled with catalyst. This catalyst is exclusively selective to CO i.

Reverse water gas shift reaction

The reverse water-gas shift reaction RWGSR , a crucial stage in the conversion of abundant CO 2 into chemicals or hydrocarbon fuels, has attracted extensive attention as a renewable system to synthesize fuels by non-traditional routes. There have been persistent efforts to synthesize catalysts for industrial applications, with attention given to the catalytic activity, CO selectivity, and thermal stability. In this review, we describe the thermodynamics, kinetics, and atomic-level mechanisms of the RWGSR in relation to efficient RWGSR catalysts consisting of supported catalysts and oxide catalysts. In addition, we rationally classify, summarize, and analyze the effects of physicochemical properties, such as the morphologies, compositions, promoting abilities, and presence of strong metal-support interactions SMSI , on the catalytic performance and CO selectivity in the RWGSR over supported catalysts. Regarding oxide catalysts i. These systematic introductions shed light on development of catalysts with high performance in RWGSR. Therefore, the extensive efforts are needed to develop CO 2 utilization technologies to address these issues Mikkelsen et al. Benefiting from plentiful low-cost CO 2 raw materials as well as the increasingly advanced CO 2 capture and separation technologies, CO 2 utilization is promising for commercial-scale applications Aresta et al. The reverse water-gas shift reaction RWGSR is an indispensable part of CO 2 utilization because it is a non-fossil route for providing feedstock for important chemical processes, such as methanol synthesis Gao et al. When it is used as an intermediate step in the direct thermochemical transformation of CO 2 to hydrocarbons, such as methane Sahebdelfar and Takht Ravanchi, ; Avanesian et al. Additionally, the RWGSR can be used to couple CO 2 with alkylene oxide or low alkanes to generate valuable chemicals, including ethylene glycol Arunajatesan et al. In contrast to the direct thermal cracking process, these coupled reactions can effortlessly break the thermodynamic equilibrium constraints and effectively accelerate their utilization Reddy et al. According to activation theory, the adsorption of CO 2 on the oxygen vacancy sites of certain catalysts initiates the first step of the RWGSR when it involves the cleavage of its own C-O bond under thermal energy-driven conditions Su et al. There are two idiographic activation mechanisms proposed for the production of CO from the RWGSR based on experimental observations and theoretical calculations Goguet et al.

Roiaz, M.

The water—gas shift reaction WGSR describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen :. The water gas shift reaction was discovered by Italian physicist Felice Fontana in It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber—Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce hydrogen. As the idea of hydrogen economy gains popularity, the focus on hydrogen as an energy storage medium when an alternative replacement energy source for hydrocarbons is used.

The catalytic conversion of CO 2 to CO via a reverse water gas shift RWGS reaction followed by well-established synthesis gas conversion technologies may provide a potential approach to convert CO 2 to valuable chemicals and fuels. However, this reaction is mildly endothermic and competed by a strongly exothermic CO 2 methanation reaction at low temperatures. Therefore, the improvement in the low-temperature activities and selectivity of the RWGS reaction is a key challenge for catalyst designs. We reviewed recent advances in the design strategies of supported metal catalysts for enhancing the activity of CO 2 conversion and its selectivity to CO. These strategies include varying support, tuning metal—support interactions, adding reducible transition metal oxide promoters, forming bimetallic alloys, adding alkali metals, and enveloping metal particles.

Reverse water gas shift reaction

The water—gas shift reaction WGSR describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen :. The water gas shift reaction was discovered by Italian physicist Felice Fontana in It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber—Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce hydrogen.

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Okabe, K. Can machine learning find extraordinary materials? Insight towards the role of ceria-based supports for reverse water gas shift reaction over RuFe nanopartilces. Tibiletti, D. Reprinted with permission from Zhang et al. To develop supported metals, both Fe oxides and Ni oxides are chosen to be investigated as representative substitutes for the most commonly used reducible supports, such as CeO 2 , ZnO, and In 2 O 3 , largely due to their oxygen vacancies with high oxygen mobility and stability, which can activate CO 2 more easily by accommodating oxygen due to the C-O bond cleavage in the RWGSR. Zhou, K. Burri, D. In contrast, the larger Pd particles, due to a higher population of terrace sites in which it is easier to form multi-bound CO and dissociated H 2 bound in the vicinity of CO, reveal a stronger interaction with CO. Our ML model revealed the effective catalyst compositions as well as the elemental features and electronic properties required for catalytic activity.

The catalytic reduction of CO 2 into value-added products has been considered a compelling solution for alleviating global warming and energy crises. The reverse water gas shift RWGS reaction plays a pivotal role among the various CO 2 utilization approaches, due to the fact that it produces syngas, the building block of numerous conversion processes. Although a lot of work has been carried out towards the development of a RWGS process, ranging from efficient catalytic systems to reactor units, and even pilot scale processes, there is still a lack of understanding of the fundamental phenomena that take place at the various levels and scales of the process.

Henle, J. The NixCe 0. Generalizing performance equations in heterogeneous catalysis from hybrid data and statistical learning. Full size image. In this study, we have applied the extrapolative ML approach to develop new multi-elemental catalysts based on supported Pt as an active metal and TiO 2 as a support for the low-temperature reverse water-gas shift RWGS reaction. Insight towards the role of ceria-based supports for reverse water gas shift reaction over RuFe nanopartilces. Characterization of iron-cobalt oxide catalysts: effect of different supports and promoters upon the structure and morphology of precursors and catalysts. PMC One of the main drivers for climate change is the release of CO 2 stemming from fossil based raw materials and products into the air. There has been significant controversy surrounding the kinetically relevant intermediate during the associative mechanism. The reverse water gas shift RWGS reaction plays a pivotal role among the various CO 2 utilization approaches, due to the fact that it produces syngas, the building block of numerous conversion processes. In order to take advantage of both the thermodynamics and kinetics of the reaction, the industrial scale water gas shift reaction is conducted in multiple adiabatic stages consisting of a high temperature shift HTS followed by a low temperature shift LTS with intersystem cooling.