Cost-effective CO2 conversion to highly demanded fuels or chemicals is challenging. Accordingly, a nanostructured Ni/CeO2-SGM catalyst synthesized by a simple sol-gel method was developed to make progress in this area for CO2 methanation. CO2 conversion reached 80.5 % and the achieved CH4 selectivity was as high as 95.8 % even at a temperature as low as 250 oC under a high gas hourly space velocity of 40,000 mL·g−1·h−1 for 106 h over Ni/CeO2-SGM. The activity of Ni/CeO2-SGM is 2–48 times of the state-of-the-art Ni/CeO2 catalysts. It was found that the high-performance mainly results from a formate pathway via a *CHO intermediate along with the significant synergy of efficient dissociation of H2 by small nickel NPs and the strong adsorption and activation of CO2 by CeO2 support. The findings with the performance of nanostructured Ni/CeO2-SGM and the associated reaction mechanism, will be significantly beneficial to development of new generation of CO2 methanation catalysts.

High-performance of nanostructured Ni/CeO2 catalyst on CO2 methanation

The carbon dioxide (CO2) methanation reaction not only provides a solution for mitigating the excessive carbon dioxide emissions but also can potentially be employed for the storage and transportat...

Essential Role of the Support for Nickel-Based CO2 Methanation Catalysts

The Power-to-Gas concept has the challenge to convert the excess of renewable electricity to synthetic natural gas, composed mainly by methane, through CO2 methanation. The superior heat transfer capacity of micro-structured reactors offers a suitable alternative for an efficient control of the reaction temperature. In the present work, the strategy of adding large amount of metal oxide promoters (15 wt.%) to nickel supported on micro-size catalysts (dp = 400–500 μm) is presented. The addition of CeO2, La2O3, Sm2O3, Y2O3 and ZrO2 was clearly beneficial, as the corresponding metal-oxide promoted catalysts exhibited higher catalytic performance than Ni/Al2O3 and the commercial reference Meth® 134 (T = 200–300 °C, P = 5 bar·g). This increase of catalytic activity is attributed to the higher amount of CO2 adsorbed on the catalyst. Among the selected promoters, La2O3 showed the highest catalytic activity (XCO2=+20% at 300 °C) due to the enhancement of nickel reducibility, nickel dispersion and the presence of moderate basic sites. In addition, Ni-La2O3/Al2O3 was stable for one week, while the unpromoted catalyst exhibited a slight decline in its activity. Accordingly, the technical catalyst proposed in this study could be used directly in compact reactors for CO2 methanation with much higher activity than the commercial reference.

Metal-oxide promoted Ni/Al2O3 as CO2 methanation micro-size catalysts

Carbon dioxide is a greenhouse gas that is abundantly found in the atmosphere. Therefore, by utilizing carbon dioxide to produce methane would not only reduce the concentration of greenhouse gas in the atmosphere but would also be able to partially fulfill the energy demand. This review highlights current trends in various active metals and heterogeneous catalyst supports used for thermal hydrogenation of CO2 to methane. Initially, the fundamentals, challenges and thermodynamic analysis are discussed to understand the limitations as well as the nature and thermodynamics of the possible reactions. In the mainstream, various classification of active metals, heterogeneous supports and structured materials with their role in selective methane production are discussed. In addition, various operating parameters, engineering aspects, morphologies and physiochemical properties have been thoroughly discussed on the catalytic performance and stability for the methanation reaction. The active metals as well as structure of catalyst have been reported to reduce the activation energy for the CO2 methanation, which is highly beneficial for the progression of the hydrogenation reaction. Finally, the mechanism of the hydrogenation reaction was also reviewed to determine its relationship with the catalyst active site structures.

Recent trends in developments of active metals and heterogenous materials for catalytic CO2 hydrogenation to renewable methane: A review

With the development and prosperity of the global economy, the emission of carbon dioxide (CO2) has become an increasing concern. Its greenhouse effect will cause serious environmental problems, such as the global warming and climate change. Therefore, the worldwide scientists have devoted great efforts to control CO2 emissions through various strategies, such as capture, resource utilization, sequestration, etc. Among these, the catalytic conversion of CO2 to methane is considered as one of the most efficient routes for resource utilization of CO2 owing to the mild reaction conditions and simple reaction device. Pioneer thermodynamic studies have revealed that low reaction temperature is beneficial to the high catalytic activity and CH4 selectivity. However, the low temperature will be adverse to the enhancement of the reaction rate due to kinetic barrier for the activation of CO2. Therefore, the invention of highly efficient catalysts with promising low temperature activities toward CO2 methanation reaction is the key solution. The Ni based catalysts have been widely investigated as the catalysts toward CO2 methanation due to their low cost and excellent catalytic performances. However, the Ni based catalysts usually perform poor low-temperature activities and stabilities. Therefore, the development of highly efficient Ni based catalysts with excellent low-temperature catalytic performances has become the research focus as well as challenge in this field. Therefore, we summarized the recent research progresses of constructing highly efficient Ni based catalysts toward CO2 methanation in this review. Specifically, the strategies on how to enhance the catalytic performances of the Ni based catalysts have been carefully reviewed, which include various influencing factors, such as catalytic supports, catalytic auxiliaries and dopants, the fabrication methods, reaction conditions, etc. Finally, the future development trend of the Ni based catalysts is also prospected, which will be helpful to the design and fabrication of the Ni catalysts with high efficiency toward CO2 methanation process.

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Recent Progresses in Constructing the Highly Efficient Ni Based Catalysts With Advanced Low-Temperature Activity Toward CO2 Methanation.

Optimization of nickel and ceria catalyst content for synthetic natural gas production through CO2 methanation

This study investigates the deactivation mechanism of CeO2-promoted catalyst for the CO2 methanation reaction. The catalytic performance was evaluated at high temperature (T = 500 °C, P = 5 bar·g) and under the presence of unfavourable H2S impurities (1–5 ppm). The thermal stability of the CeO2-promoted catalyst was excellent, while the non-promoted sample suffered from nickel sintering. In contrast, the presence of H2S was detrimental for both catalysts. The tolerance to H2S of CeO2-promoted sample was higher; keeping one third of the initial catalytic activity under continuous addition of H2S. The identification of crystallographic planes associated with Ce2O2S phase (HRSTEM) evidenced that the addition of CeO2 to nickel catalyst minimized the formation of non-active NiS sites. This finding was further confirmed through DRIFT spectroscopy since for the Ni-CeO2/γ-Al2O3, methane formation derived from formate dissociation was followed by hydrogenation of the adsorbed CO on the remaining available active sites.

Higher tolerance to sulfur poisoning in CO2 methanation by the presence of CeO2

Within the Power-to-Gas concept, the catalytic conversion of renewable hydrogen and carbon dioxide to methane for injection to the gas grid has recently attracted much attention. In the present work, the implementation of a nickel–ceria–alumina catalyst on a multitubular reactor for CO2 methanation was studied. The reaction kinetics were experimentally obtained and considered for a CFD model by means of Ansys® Fluent software, to evaluate the behaviour of a multitubular heat-exchange reactor. The simulations showed that most reaction occurs at the beginning of the reactor tube and the temperature raises rapidly. At the kinetic regime zone, a proper control of the temperature is required to avoid excessive hot-spots. In contrast, the final reactor volume is mainly controlled by the reaction thermodynamics. In this zone, the reaction is shifted toward products by using a cooling medium at low temperature. The effect of several design variables on the final methane yield and on the temperature profile was carried out, and finally, a reactor able to convert the CO2 present in the biogas to synthetic natural gas is proposed. The modelling showed that the proposed reactor tube (di = 9 mm and L = 250 mm) should be able to obtain a high methane content (>95%), at high GHSV (14,400 h−1), and keeping the hot-spots at minimum (Δ100 K). Within this reactor design approach, almost 1000 of tubes are necessary for the methanation of a medium-size biogas plant.

CO2 conversion to synthetic natural gas: Reactor design over Ni–Ce/Al2O3 catalyst

Process intensification leads to a substantially smaller process technology. In this work, we present a combination of an active microsize catalyst and an effective microstructured reactor technolo...

Andreina Alarcón

Papers

Metal-oxide promoted Ni/Al2O3 as CO2 methanation micro-size catalysts

Optimization of nickel and ceria catalyst content for synthetic natural gas production through CO2 methanation

Higher tolerance to sulfur poisoning in CO2 methanation by the presence of CeO2

CO2 conversion to synthetic natural gas: Reactor design over Ni–Ce/Al2O3 catalyst

Pushing the Limits of SNG Process Intensification: High GHSV Operation at Pilot Scale