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Anthropogenic CO 2 emissions are considered the major contributor of greenhouse gas emissions worldwide. The mitigation of this kind of CO 2 emissions relies on a portfolio of alternatives where CO 2 absorption appears as the nearest approach to be applied at industrial scale. Researchers have been focused on developing new formulations of solvents to make more competitive CO 2 absorption as a carbon capture and storage (CCS) technology. In this sense, this chapter summarizes both the conventional solvents and the most recent investigations on this field. Chemical absorption is more suitable for a lot of industrial process due to the flue gas conditions: ambient pressure, low CO 2 concentration and large volume. Therefore numerous novel solvents came up in recent years and they are further discussed in this chapter. The most recent solvents, their mechanisms and kinetics and the advantages and disadvantages are also included. Finally, physical solvents are adequate in high CO 2 partial pressure applications and they are reported in the last section. Although physical absorption field is constrained to high-pressure flue gas, physical solvents provided higher performance in CO 2 separation process and their characteristics are also summarized.

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Se ha propuesto y puesto en práctica una nueva metodología de aprendizaje basado en problemas en una

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The exponential growth of greenhouse gas emissions and their associated climate change problems have motivated the development of strategies to reduce CO2 levels via CO2 capture and conversion. Reverse water gas shift (RWGS) reaction has been targeted as a promising pathway to convert CO2 into syngas which is the primary reactive in several reactions to obtain high-value chemicals. Among the different catalysts reported for RWGS, the nickel-based catalyst has been proposed as an alternative to the expensive noble metal catalyst. However, Ni-based catalysts tend to be less active in RWGS reaction conditions due to preference to CO2 methanation reaction and to the sintering and coke formation. Due to this, the aim of this work is to study the effect of the potassium (K) in Ni/CeO2 catalyst seeking the optimal catalyst for low-temperature RWGS reaction. We synthesised Ni-based catalyst with different amounts of K:Ni ratio (0.5:10, 1:10, and 2:10) and fully characterised using different physicochemical techniques where was observed the modification on the surface characteristics as a function of the amount of K. Furthermore, it was observed an improvement in the CO selectivity at a lower temperature as a result of the K-Ni-support interactions but also a decrease on the CO2 conversion. The 1K catalyst presented the best compromise between CO2 conversion, suppression of CO2 methanation and enhancing CO selectivity. Finally, the experimental results were contrasted with the trends obtained from the thermodynamics process modelling observing that the result follows in good agreement with the modelling trends giving evidence of the promising behaviour of the designed catalysts in CO2 high-scale units.

BACKGROUND Control of greenhouse gas emissions has become one of the most important challenges faced by humanity. Among the various approaches to mitigating CO2 emissions, carbon capture and storage (CCS) is considered one of the most promising clean coal options for the future because it can be implemented in the short and medium terms at the industrial scale. Among CCS techniques, oxy‐combustion offers advantages in using pure oxygen (O2) as a comburent, where in a flue gas composed mainly of CO2 and water vapor is generated. Cryogenic air separation is the only available technology that can provide the required amount of O2, but this process requires large amounts of energy and is costly, which make its large‐scales implementation difficult. RESULTS In this framework, oxygen transport membranes are being researched as an O2 supplier unit because they offer advantages from a techno‐economic view point. In the present work, the thermochemical stabilities of La0.6Sr0.4Co0.2Fe0.8O3 and Cobalt‐doped Ce0.9Gd0.1O were evaluated to obtain information on their behavior in oxy‐combustion atmospheres. Experiments were performed in a circulating fluidized bed boiler of a pilot plant using an experimental sampling train. Samples of the two materials were characterized by X‐ray diffraction, X‐ray fluorescence, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, and Brunauer–Emmett–Teller analysis. CONCLUSIONS The results revealed that both materials were susceptible to the presence of species that originated from flue gas, materials comprising the boiler and ducts, and coal ash, and that the CGO_Co material showed better performance than the other studied material. © 2020 Society of Chemical Industry