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This paper evidences the viability of chemical recycling of CO 2 via reverse water-gas shift reaction using advanced heterogeneous catalysts. In particular, we have developed a multicomponent Fe-Cu-Cs/Al 2 O 3 catalyst able to reach high levels of CO 2 conversions and complete selectivity to CO at various reaction conditions (temperature and space velocities). In addition, to the excellent activity, the novel-Cs doped catalyst is fairly stable for continuous operation which suggests its viability for deeper studies in the reverse water-gas shift reaction. The catalytic activity and selectivity of this new material have been carefully compared to that of Fe/Al 2 O 3 , Fe-Cu/Al 2 O 3 and Fe-Cs/Al 2 O 3 in order to understand each active component’s contribution to the catalyst’s performance. This comparison provides some clues to explain the superiority of the multicomponent Fe-Cu-Cs/Al 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]

Transition to low carbon societies requires advanced catalysis and reaction engineering to pursue green routes for fuels and chemicals production as well as CO 2 conversion. This comprehensive review provides a fresh perspective on the dry reforming of methane reaction (DRM) which constitutes a straightforward approach for effective CO 2 conversion to added value syngas. The bottleneck for the implementation of this process at industrial scale is the development of highly active and robust heterogeneous catalysts able to overcome the CO 2 activation barrier and deliver sufficient amount of the upgrading products at the desired operation conditions. Also, its high energy demand due to the endothermic nature of the reaction imposes extra difficulties. This review critically discusses the recent progresses on catalysts design ranging from traditional metal-supported catalysts to advanced structured and nanostructured systems with promising performance. The main advantages and culprits of the different catalytic systems are introduced aiming to inspire the catalysis community to further refine these formulations towards the development of "supercatalysts" for DRM. Besides the design of increasingly complex catalyst morphologies as well as other promising alternatives aiming at reducing the energy consumption of the process or tackle deactivation through reactor design are introduced. [ABSTRACT FROM AUTHOR]

• Biogas upgrading through CO 2 utilization and waste recycling is proposed. • Flue-Gas Desulfurization Gypsum as precipitant for definitely CO 2 storage. • Precipitation efficiency is modelled using DesignExpert software. • The physicochemical properties of the final product are analysed. • Our work confirms the success of the proposed strategy. Herein a novel process to synergize biogas upgrading, CO 2 utilization and waste recycling is proposed. Our study emerges as a promising strategy within the circular economy. In this work, the technical feasibility of Flue-Gas Desulfurization Gypsum as precipitant for definitely CO 2 storage is studied. The precipitation stage is evaluated through two key factors: the quality of the carbonate product and the precipitation efficiency obtained. The physicochemical characterization of the solid carbonate product was analysed by means of Raman, X-Ray diffraction and scanning electron microscopy. The precipitation efficiency is evaluated through the variation of the main precipitation parameters (temperature, molar ratio and time). For this purpose, two groups of experiments were performed. The first group was aimed to model the precipitation system through experiments designed with DesignExpert vs.12 software. The second group of experiments allows to compare our results with pure species as precipitants, as well as to validate the model designed. The physicochemical characterization performed reveals high purity calcite as product. Encouraging precipitation efficiencies were obtained, ranging from 53.09–80.09% (66 % average). Furthermore, the model reveals a high influence of the molar ratio (3–5 times higher impact than other parameters) and low influence of temperature, which evidences the low energy consumption of the proposal. To optimize energy consumption, the model suggests 33 sets of parameters values. Examples of these values are 20 °C, 1.5 mol/mol, and 30 min, which allow to obtain a 72.57 % precipitation efficiency. Overall, this study confirms the technical feasibility of this circular economy approach. [ABSTRACT FROM AUTHOR]

This review discusses the importance of mitigating CO 2 emissions by valorizing CO 2 through high-pressure catalytic processes. It focuses on various key processes, including CO 2 methanation, reverse water-gas shift, methane dry reforming, methanol, and dimethyl ether synthesis, emphasizing pros and cons of high-pressure operation. CO 2 methanation, methanol synthesis, and dimethyl ether synthesis reactions are thermodynamically favored under high-pressure conditions. However, in the case of methane dry reforming and reverse water-gas shift, applying high pressure, results in decreased selectivity toward desired products and an increase in coke production, which can be detrimental to both the catalyst and the reaction system. Nevertheless, high-pressure utilization proves industrially advantageous for cost reduction when these processes are integrated with Fischer-Tropsch or methanol synthesis units. This review also compiles recent advances in heterogeneous catalysts design for high-pressure applications. By examining the impact of pressure on CO 2 valorization and the state of the art, this work contributes to improving scientific understanding and optimizing these processes for sustainable CO 2 management, as well as addressing challenges in high-pressure CO 2 valorization that are crucial for industrial scaling-up. This includes the development of cost-effective and robust reactor materials and the development of low-cost catalysts that yield improved selectivity and long-term stability under realistic working environments. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work a novel strategy for bio-methane production and magnesium chloride waste valorization is addressed. The proposed process is a potential alternative path to the already existing biogas upgrading technologies by carbon dioxide mineralization into valuable magnesium carbonate. The main parameters affecting the precipitation efficiency (reaction time, reaction temperature, and molar ratio reactant/precipitator) are studied, leading to promising results which spark further investigation in this innovative route. Additionally the purity and the morphology of the obtained solid product was accurately analysed through different physicochemical characterization techniques such as Raman, X-Ray diffraction and Scanning electron microscope. The characterisation study reveals a mixture of Nesqueonite and Dypingite carbonate phases obtained in the process being the later the dominant phase in the resulting precipitate. Overall, the results discussed herein confirmed the technical feasibility of this innovative strategy for synergizing carbon dioxide mineralization and renewable energy production. • A novel strategy for biogas upgrading based on MgCl 2 residues is proposed. • Effect of time, temperature and molar ratio reactant/precipitator was studied. • Rama, XRD and SEM were employed to confirm the product quality obtained. • Our work confirms the success of the proposed strategy for biogas upgrading biogas. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly efficient Mo 2 C catalysts for CO 2 conversion via RWGS • Cu as a promoter boost the CO 2 conversion due to higher active sites concentration. • Cs is an excellent dopant to enhance CO selectivity, especially at low temperatures. • Electronic interactions and re-carburisation accounting for Cs positive effect • Robust catalysts for long term operations. Abstract Mo 2 C is an effective catalyst for chemical CO 2 upgrading via reverse water-gas shift (RWGS). In this work, we demonstrate that the activity and selectivity of this system can be boosted by the addition of promoters such as Cu and Cs. The addition of Cu incorporates extra active sites such as Cu+ and Cu° which are essential for the reaction. Cs is an underexplored dopant whose marked electropositive character generates electronic perturbations on the catalyst's surface leading to enhanced catalytic performance. Also, the Cs-doped catalyst seems to be in-situ activated due to a re-carburization phenomenon which results in fairly stable catalysts for continuous operations. Overall, this work showcases a strategy to design highly efficient catalysts based on promoted β-Mo 2 C for CO 2 recycling via RWGS. [ABSTRACT FROM AUTHOR]

CO 2 utilisation is becoming an appealing topic in catalysis science due to the urgent need to deal with greenhouse gases (GHG) emissions. Herein, the dry reforming of methane (DRM) represents a viable route to convert CO 2 and CH 4 (two of the major GHG) into syngas, a highly valuable intermediate in chemical synthesis. Nickel-based catalysts are economically viable materials for this reaction, however they show inevitable signs of deactivation. In this work stabilisation of Ni in a pyrochlore-perovskite structure is reported as a viable method to prevent fast deactivation. Substitution of Zirconium by Ni at various loadings in the lanthanum zirconate pyrochlore La 2 Zr 2 O 7 is investigated in terms of reactant conversions under various reaction conditions (temperature and space velocity). XRD analysis of the calcined and reduced catalysts showed the formation of crystalline phases corresponding to the pyrochlore structure La 2 Zr 2-x Ni x O 7 -δ and an additional La 2 NiZrO 6 perovskite phase at high Ni loadings. Carbon formation is limited using this formulation strategy and, as a consequence, our best catalyst shows excellent activity for DRM at temperatures as low as 600 °C and displays great stability over 350 h of continuous operation. Exsolution of Ni from the oxide structure, leading to small and well dispersed Ni clusters, could explain the enhanced performance. [ABSTRACT FROM AUTHOR]

In the context of Carbon Capture and Utilisation (CCU), the catalytic reduction of CO 2 to CO via reverse water-gas shift (RWGS) reaction is a desirable route for CO 2 valorisation. Herein, we have developed highly effective Ni-based catalysts for this reaction. Our study reveals that CeO 2 -Al 2 O 3 is an excellent support for this process helping to achieve high degrees of CO 2 conversions. Interestingly, FeO x and CrO x , which are well-known active components for the forward shift reaction, have opposite effects when used as promoters in the RWGS reaction. The use of iron remarkably boosts the activity, selectivity and stability of the Ni-based catalysts, while adding chromium results detrimental to the overall catalytic performance. In fact, the iron-doped material was tested under extreme conditions (in terms of space velocity) displaying fairly good activity/stability results. This indicates that this sort of catalysts could be potentially used to design compact RWGS reactors for flexible CO 2 utilisation units. [ABSTRACT FROM AUTHOR]