Catalysts For CO2 Methanation Research Articles

Identification of Deactivation Mechanisms by the Periodic Transient Kinetic Method

AbstractThe understanding of deactivation processes in heterogeneous catalysis is key for the development of new materials and exploration of new operation windows. In this contribution, the periodic transient kinetic method (PTK) is used to identify and separate catalyst deactivation processes for the first time. The PTK method is applied for a standard Ni/Al2O3 catalyst in CO and CO2 methanation for 24 h and compared to steady‐state experiments. For the example reactions, the study exhibits different deactivation behavior for CO and CO2 methanation. The results demonstrate that the PTK method delivers an insight into the deactivation process and furthermore gives evidence for the underlying mechanism.

Ni Catalysts for Thermochemical CO2 Methanation: A Review

Ni Catalysts for Thermochemical CO2 Methanation: A Review

NiO Nano- and Microparticles Prepared by Solvothermal Method—Amazing Catalysts for CO2 Methanation

Nickel oxide (NiO) is one of the most popular hydrogenation catalysts. In heterogeneous catalysis, nickel oxide is used, for example, as a suitable methanation catalyst in the Fischer–Tropsch reaction not only for CO hydrogenation but also in the modified Fischer–Tropsch reaction with CO2. However, CH4 selectivity and CO2 conversion strongly depend on NiO micro- (MPs) and nanoparticles’ (NPs) shape, size, and surface area. In this study, the synthesis of NiO micro- and nanoparticles was conducted using the simple solvothermal method. Different morphologies (microspheres, sheet clusters, hexagonal microparticles, and nanodiscs) were prepared using this method with different solvents and stabilizers. The prepared catalysts were tested in the hydrogenation of CO2 in a gas phase with excellent conversion values and high selectivity to produce CH4. The best results were obtained with the NiO with disc or sphere morphology, which produced methane with selectivity at a level near 100% and conversion close to 90%.

Facilitating CO2 methanation over oxygen vacancy-rich Ni/CeO2: Insights into the synergistic effect between oxygen vacancy and metal-support interaction

The catalytic hydrogenation of CO2 into CH4 is a versatile strategy to realize green development goals, whereas developing low-cost and high-performance catalysts remains a significant challenge. Herein, highly active Ni0/NiO supported on oxygen vacancy-rich CeO2 (Ni/CeO2-Ov-R) was designed, which exhibited ∼76 % CO2 conversion coupled with 100 % CH4 selectivity at a low temperature of 250 °C. In addition, such satisfactory reaction performance could be maintained over 80 h at 300 °C. The density functional theory (DFT) calculations elaborated that oxygen vacancies were more easily formed on the CeO2 (1 1 0) plane of Ni/CeO2-Ov-R. Compared with Ni/CeO2-Ov-medium (Ni/CeO2-Ov-M) and Ni/CeO2-Ov-poor (Ni/CeO2-Ov-P) with relatively insufficient oxygen vacancy, the copious oxygen vacancies of Ni/CeO2-Ov-rich was apt to enhance the interaction between the CeO2 support and Ni species as confirmed through H2-TPR and XPS. Noteworthily, the abundant medium-strength basic sites and surface oxygen vacancy of Ni/CeO2-Ov-rich were more conducive to upshifting the activation adsorption of CO2 and accelerate the conversion of intermediates. Besides, the oxygen vacancies also make a great contribution to the enhancement of the potential for hydrogen dissociation because of the enhanced number of exposed Ni0. In situ DRIFTS displayed that the CO and formate (HCOO–) routes co-existed on Ni/CeO2 catalysts, revealing that oxygen vacancy and exposed Ni0 boosted the CO2 and H2 activation. This work proposes a deeper insight into the precise regulation of the oxygen vacancy of Ni/CeO2 catalyst and opens a path for exploiting CO2 methanation catalysts with a potential application.

Cobalt-doped Ni-based catalysts for low-temperature CO2 methanation

The study of the process and mechanism of CO2 activation and the development of low-temperature, high-activity and selective catalysts for CO2 methanation are current research hotspots. In this paper, a series of Ni/Al2O3 catalysts with different Co contents were prepared by using layered double hydroxides (LDHs) as precursors for low-temperature CO2 methanation, and the incorporation of Co promoted the electron transfer from Ni to Co, which facilitated the adsorption and activation of CO2 and H2. The spent catalyst still maintained the layered structure with no significant change in the metal particle size, indicating that the addition of Co significantly improved the long-term stability of the catalysts. The CO2 conversion was 55.5 % and STYCH4 was 148.0 mmol·gcat−1 h−1 at 200 °C, 2.0 MPa and 1000 h−1. The in situ DRIFTS experiments showed that the addition of Co accelerated the conversion of the reaction intermediates and promoted the generation of methane.

Efficiency study of nickel-containing glass-fiber catalysts for CO2 methanation

The work is dedicated to the synthesis and investigation of Ni-containing catalysts based on glass-fiber carriers (GFC) with an additionally deposited secondary layer of porous SiO2 for the process of carbon dioxide methanation. Ni-based GFCs were prepared using the surface thermosynthesis (STS) and pulse surface thermosynthesis (PSTS) methods, involves heat treatment of the catalyst with the supported Ni precursor at a high heating rate; such procedure was not applied earlier for production of CO2 methanation catalysts. The GFC sample prepared by the PSTS method with a fuel additive in the precursor composition is characterized by a more uniform distribution of Ni particles on the catalyst surface and better dispersion of Ni, smaller crystallite size: NiO crystallites in this freshly prepared GFCs are smaller than 10 nm and Ni crystallites in reduced catalysts are <30 nm. As a result, this sample demonstrated the highest apparent activity in the methanation reaction among all synthesized GFCs, it has also showed a significantly higher specific activity per unit mass of nickel compared to the commercial Ni-Al2O3 analogue. The synthesized catalysts are original, they can be effectively applied for development of novel highly efficient technologies for energy conversion/storage systems and greenhouse gas emission control.

Improvement in the activity of Ru/ZrO2 for CO2 methanation by the enhanced hydrophilicity of zirconia

Increasing interests in the supported Ru catalysts for CO2 methanation can be recently found in the literature. In this work, we demonstrated that the enhanced surface hydrophilicity of ZrO2 via air plasma treatment has significant effects on the properties of Ru/ZrO2 catalyst for CO2 methanation. At the same CO2 conversions, the reaction temperature over the catalysts on ZrO2 with enhanced hydrophilicity is 20–70 °C lower than those on untreated ZrO2. The catalyst characterization confirms that the enhanced hydrophilicity leads to more hydroxyl groups and oxygen vacancies on the support, which further promotes CO2 adsorption and activation, facilitating the conversion of CO2 to HCO3* and HCOO* in formate pathway. The enhanced hydrophilicity also causes a high Ru dispersion with stronger electronic interaction between Ru and ZrO2, which forms more interfacial active sites and improves the adsorption and dissociation of H2, promoting the linear-CO-Ru0 adsorption in CO* pathway.

Ba2+ doping into Ni/Al2O3 nanofibers promotes CO2 methanation via alkaline modulation

Ni-based catalysts are promising catalysts for CO2 methanation due to low lost. However, the activity and selectivity of Ni-based catalysts in CO2 methanation at low temperatures still need to be improved. Here, Ni4Al2BamOx (m = 0–0.5) nanofibers were prepared. Doping Ba2+ would increase alkaline sites and facilitate generating oxygen vacancies. Especially, Ni4Al2Ba0.2Ox exhibited the high specific surface area with 127.1 m2 g−1, being potential for exposing more active sites. Indeed, compared with undoped Ni4Al2Ox catalysts (CO2 conv. = 45 %, CH4 select. = 92 % at 300 °C), Ba2+ doping significantly improved activity (CO2 conv. = 74 %, CH4 select. = 99 % at 300 °C) and stability within 200 h for Ni4Al2Ba0.2Ox. Both EPR and O1S XPS confirmed that Ni4Al2Ba0.2Ox can form more oxygen vacancies and CO2-TPD confirmed that Ni4Al2Ba0.2Ox had stronger CO2 adsorption capacity compared to Ni4Al2Ox. In-situ infrared spectroscopy and DFT calculations both indicated that Ba2+ doping can promote generating surface hydroxyl groups and formate pathways.

The effect of calcination gas atmosphere on the structural organization of Ru/Ce0.75Zr0.25O2 catalysts for CO2 methanation

In this study, supported 5 wt% Ru/Ce0.75Zr0.25O2 catalysts were prepared by sorption-hydrolytic deposition technique, followed by calcination under different conditions, namely in reductive H2/N2 (Ru/CeZr_red) and oxidative air (Ru/CeZr_ox) atmospheres. A thorough characterization of the catalysts was carried out by XRD, CO chemisorption, HRTEM, Raman spectroscopy, XPS, and in situ DRIFTS. The findings showed that the choice of the calcination atmosphere has a great impact on the structural organization of the catalyst. Calcination in air results in the formation of the larger crystalline RuO2 particles, which tend to enlarge upon reduction under CO2 methanation conditions. The reductive treatment results in a much higher dispersion of supported Ru species and a more pronounced metal-support interaction (MSI). In the Ru/CeZr_red catalyst, a large amount of atomic scale Ru species was detected along with metallic Ru nanoparticles and clusters. However, it was found that the superiority of the Ru/CeZr_red catalyst in the Ru dispersion did not result in the significant advantage in the CO2 methanation activity. In situ DRIFTS results suggested that the MSI affects the ability of Ru species to adsorb and activate reagent molecules, in particular, enhances the adsorption strength of the intermediate CO species.

Modulating nickel precursors to construct highly active Ni/Y2O3 catalysts for CO2 methanation

Constructing the interface of Ni/Y2O3 heterogeneous catalyst is a feasible strategy for efficient catalyst design in CO2 methanation, which can create the active Y–O–Ni interfacial sites by utilizing the interaction between Ni and Y2O3. In this work, the strategy of using different nickel precursors (nickel nitrate, nickel acetate, basic nickel carbonate and nickel citrate) was used to prepare various Ni-based catalysts supported on Y2O3, which were estimated for their catalytic performance on CO2 methanation. The catalysts were characterized based on BET, XRD, TEM, H2-TPR, XPS and CO2-TPD, etc. The results indicated a close correlation between the metal dispersion and particle size of Ni/Y2O3 catalysts and the nickel precursor employed. The Y–O–Ni interface structure in Ni/Y2O3 catalysts, associated with basic sites, provides a richer source of basic sites, offering more active sites for CO2 adsorption and activation. Ni/Y2O3 catalyst prepared with nickel nitrate as the precursor exhibited characteristics such as a highly enhanced nickel dispersion, a smaller nickel particle size, and more abundant metallic Ni0 sites. Moreover, nickel nitrate-derived Ni/Y2O3 catalyst exhibited optimal catalytic activity, achieving a CO2 conversion rate of up to 92 % at 300 °C, with 100 % selectivity to CH4, and displaying good stability over 30 h. Therefore, the dispersion of Ni and the size of Ni particles could be controlled by adjusting the precursor, which is closely associated with the catalytic activity of Ni/Y2O3 catalyst. This work unveils the interface-property relationship of Ni/Y2O3 catalysts and provides a new insight into strategy of constructing more effective Ni-based catalyst for CO2 methanation through the controlled nickel precursor.

RuCo/ZrO2 Tandem Catalysts with Photothermal Confinement Effect for Enhanced CO2 Methanation.

Photothermal CO2 methanation reaction represents a promising strategy for addressing CO2-related environmental issues. The presence of efficient tandem catalytic sites with a localized high-temperature is an effective pathway to enhance the performance of CO2 methanation. Here the bimetallic RuCo nanoparticles anchored on ZrO2 fiber cotton (RuCo/ZrO2) as a photothermal catalyst for CO2 methanation are prepared. A significant photothermal CO2 methanation performance with optimal CH4 selectivity (99%) and rate (169.93mmol gcat -1 h-1) is achieved. The photothermal energy of the RuCo bimetallic nanoparticles, confined by the infrared insulation and low thermal conductivity of the ZrO2 fiber cotton (ZrO2 FC), provides a localized high-temperature. In situ spectroscopic experiments on RuCo/ZrO2, Ru/ZrO2, and Co/ZrO2 indicate that the construction of tandem catalytic sites, where the Co site favors CO2 conversion to CO while incorporating Ru enhances CO* adsorption for subsequent hydrogenation, results in a higher selectivity toward CH4. This work opens a new insight into designing tandem catalysts with a photothermal confinement effect in CO2 methanation reaction.

Adjacent Reaction Sites of Atomic Mn2O3 and Oxygen Vacancies Facilitate CO2 Activation for Enhanced CH4 Production on TiO2-Supported Nickel-Hydroxide Nanoparticles

The catalytic conversion of carbon dioxide (CO2) to methane (CH4) through the “Sabatier reaction”, also known as CO2 methanation, presents a promising avenue for establishing a closed carbon loop. However, the competitive reverse water gas shift (RWGS) reaction severely limits CH4 production at lower temperatures; therefore, developing highly efficient and selective catalysts for CO2 methanation is imperative. In this regard, we have developed a novel nanocatalyst comprising atomic scale Mn2O3 species decorated in the defect sites of TiO2-supported Ni-hydroxide nanoparticles with abundant oxygen vacancies (hereafter denoted as NiMn-1). The as-prepared NiMn-1 catalyst initiates the CO2 methanation at a temperature of 523 K and delivers an optimal CH4 production yield of 21,312 mmol g−1 h−1 with a CH4 selectivity as high as ~92% at 573 K, which is 45% higher as compared to its monometallic counterpart Ni-TiO2 (14,741 mmol g−1 h−1). Physical investigations combined with gas chromatography analysis corroborate that the exceptional activity and selectivity of the NiMn-1 catalyst stem from the synergistic cooperation between adjacent active sites on its surface. Specifically, the high density of oxygen vacancies in Ni-hydroxide and adjacent Mn2O3 domains facilitate CO2 activation, while the metallic Ni domains trigger H2 splitting. We envision that the obtained results pave the way for the design of highly active and selective catalysts for CO2 methanation.

Highly Stable and Selective Ni/ZrO2 Nanofiber Catalysts for Efficient CO2 Methanation.

Ni-based oxides are promising catalysts for CO2 methanation. However, Ni-based catalysts also have some unresolved issues and drawbacks in practical applications. The activity and selectivity of Ni-based catalysts in CO2 methanation at low temperatures still need to be improved. Here, Ni/ZrO2 nanofibers with high surface areas (up to 101.2 m2/g) were prepared by electrospinning methods. The Ni/ZrO2-ES (also named as 66Ni/ZrO2) catalyst showed excellent catalytic performance in CO2 methanation (the CO2 conversion = 81% and CH4 selectivity = 99% at 350 °C) and excellent stability for 100 h, which was better than most reported Ni/ZrO2 catalysts. However, the comparison sample Ni/ZrO2-CP prepared by the coprecipitation method had poor catalytic performance (the CO2 conversion = 54% and CH4 selectivity = 90% at 350 °C). Within 100 h, the CO2 conversion decreased to 30% and the CH4 selectivity decreased to 52%. Both EPR and O1S XPS confirmed that Ni/ZrO2 nanofibers can form more reactive oxygen species vacancies, and CO2-TPD confirmed that nanofibers had more CO2 adsorption sites compared with the control sample Ni/ZrO2-CP. In situ DRIFTS analysis showed that bidentate carbonate and monodentate carbonate were key intermediates in CO2 methanation. The catalytic performance of Ni/ZrO2 nanofiber catalysts would be attributed to higher dispersion of Ni species on the surface of nanofibers, high specific surface area (101.2 m2/g), more oxygen vacancies, more CO2 adsorption sites, and the synergistic effect between Ni nanoparticles and ZrO2 nanofibers. This work may inspire the rational design of Ni/ZrO2 nanofiber catalysts with rich oxygen vacancies for low-temperature CO2 methanation.

Boosting low temperature CO2 methanation by tailoring Co species of CoAlO catalysts

The development of low-temperature CO2 methanation catalysts with excellent performance has been challenging. Herein, we report a CoAlO catalyst derived from layered double hydroxide (LDH) that modulates the Co species of a multifunctional catalyst through a reduction process. The CoAlO catalyst with a surface-coated CoO film achieved CO2 conversion up to 29.0 % at 160 °C, which was superior to that of noble metal catalysts. The multiple characterizations were used to reveal the relationship between the catalytic activity and the chemical state of Co species. The results showed that the reaction followed the H-assisted activation pathway, where the rate of formate intermediates generation determined the overall reactivity. Meanwhile, the reduction–oxidation (RO) process in the catalyst preparation and the water generated in the reaction could reduce the size of Co particles, which were favorable for CO2 activation. This work offers a promising catalyst design for low-temperature methanation reaction.

Space confinement effect of carbon nanotube-alumina strip support on the Cu-Co catalysts for CO2 methanation

The present work reported the space confinement effect of carbon nanotube-alumina strip (CAS) support on the Cu-Co bimetallic catalyst or the single Cu, Co catalysts for the CO2 methanation. CAS, made by extrusion of nanotubes and Al-based sol and high temperature calcination, was a macroscopic support with sufficient mesopores and hydrophobic property. Cu-Co/CAS catalysts exhibited high catalytic activity for methanation of CO2 (H2/CO2=3:1), where CO2 conversion was 49.62% and CH4 selectivity was 95.98% at temperature as low as 250 ℃ and 1.5 MPa, and showed advantage significantly over those with the supports of individual nanotube or pure Alumina support. The comparison suggested the hydrophobicity of carbon nanotubes can effectively remove water from the metal active sites, enhancing the equilibrium of reverse water gas shift and CO methanation reactions, as compared to alumina support. Additionally, CAS support had a spatial confinement effect that increased the contact time of CO2 or intermediates with the active sites, compared with individual nanotube support. XPS and Raman spectroscopy validated the presence of oxygen vacancies of CAS, promoting the CO2 methanation. H2-TPR results, in combination with DFT calculations, confirmed that the CAS supports enabled the Cu-Co active phase by changing their electronic structures, to possess a strong adsorption activation capacity for H2 at low temperatures with high performance for CO2 methanation.

Bimetallic Ni-Fe Supported by Gadolinium Doped Ceria (GDC) Catalyst for CO2 Methanation

CO2 conversion into fuels and high value-added chemical feedstocks, such as methane, has gained novel interest as a crucial process for further manufacturing multi-carbon products. Methane, CH4, becomes a promising alternative for environmental and energy supply issues. Nickel-based catalysts were found to be very active and selective for CH4 production. The use of promoter and support material to develop high activity, high selectivity, and durable catalysts for CO2 methanation at low temperature is a challenge. Gadolinium-Doped Ceria (GDC) has been known as material for Solid Oxide Fuel Cell (SOFC) and Solid Oxide Electrolysis Cell (SOEC) due to higher ionic conductivity and lower operating temperatures. However, few researches have been done regarding to CO2 methanation over GDC as catalyst support so far. In this present work, CO2 methanation was investigated over bimetallic Ni-Fe catalyst supported by GDC. The results showed that CH4 production rate by using Ni-Fe/GDC catalyst was higher than that of GDC at all reaction temperatures carried on. Ni-Fe/GDC showed remarkable CH4 production rate as of 17.73 mmol.gcat−1.h−1 at 280 °C. No catalytic activity was produced by GDC catalyst only. The highest CO2 conversion (46.50%) was observed at 280 °C, with almost 100% selectivity to CH4. The turnover frequency (TOF) value of Ni-Fe/GDC (4529.32 h−1) was the highest than that of Ni and common CO2 methanation catalyst, Ni/Al2O3 catalysts at 280 °C, further displaying the outstanding low-temperature catalytic activity. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Simultaneously quantitative and qualitative regulation of active sites of Ni-phyllosilicate for enhanced CO2 hydrogenation to methane

To address the problems of low metal utilization rate and poor low-temperature activity of the nickel phyllosilicate catalysts for CO2 methanation, this work prepared ultrathin defect-rich Ni-phyllosilicate through ball milling method in the presence of H2O2 modifier, which simultaneously created active sites with more quantity and higher quality. The instantaneous temperature and high pressure derived from the collision and friction of grinding balls provided driving force for the Ni-phyllosilicate synthesis, and the shear force destroyed the interlayer forces to construct the ultrathin layers. H2O2 molecule could insert the layers and dissociate to O2 bubbles, whose cavitation effect created holes and defects in the nickel phyllosilicate nanosheets and SiO2 spheres. H2O2 amount was crucial for the defect construction and the optimum Ni-AA-1H catalyst possessed the ultrathin nanosheet of 0.68 nm and high Ni dispersion of 15.6 %, whose TOFCO2 reached 3.76 × 10−2 s−1 at 160 °C. The in-situ DRIFTS results confirmed the enhanced low-temperature activity and the HCOO− reaction pathway over Ni-AA-1H for CO2 methanation. Nickel precursor effect was also investigated, and nickel acetylacetonate was determined as the optimal one compared with nickel acetate and nickel chloride, owing to the high steric effect of CH3COCHCOCH3− group and strong basicity environment during ball milling process.

Robust stability of La- and Ce- dual-promoted Ni/ZrO2 catalyst for CO2 methanation

The sintering issue of Ni nanoparticles seriously limits the practical application of the Ni-based catalysts for CO2 methanation. This work demonstrates that the La- and Ce- dual-promoted Ni/ZrO2 shows better durability at 600 ºC and 60000 mL gcat−1 h−1 over 200 h compared with the La- or Ce- single-promoted. The composition and microstructure characterization indicates that the dispersion and sintering resistance of Ni nanoparticles is enhanced with the dual-promoted catalysts. Both depth profile of X-ray photoelectron spectroscopy and density functional theory calculation show that in the La- and Ce- dual-promoted Ni/ZrO2, the reduced dissolution of Ce into ZrO2 lattice and the spread of La on ZrO2 surface by forming a La2O3-CeO2 solid solution improves the dispersion and stability of Ni nanoparticles. This work provides a facile strategy to mitigate the sintering of Ni nanoparticles and thus improve the stability of Ni-based catalysts for CO2 methanation.

Optimizing Low-Temperature CO2 methanation with Aluminum-Doped Ni/CeO2 Catalysts: Insights into reaction pathway adjustments and strong Metal-Support interactions

Revealing the logical relationship between the structure, reaction mechanism and performance of the catalyst is a key step in the design of low-temperature CO2 methanation catalyst. The elemental Al was introduced into Ni/CeO2 using a co-precipitation method to form a composite support CeO2-Al2O3 loaded nickel-based catalyst. It was found that the incorporation of Al significantly improved the catalytic performance of low-temperature CO2 methanation. Notably, at a molar ratio of Al/Ce equal to 0.1, the catalyst exhibited optimal CO2 conversion of 88.83% and CH4 selectivity of 99.96% at 240 ℃. The addition of appropriate amounts of Al not only increases the specific surface area of the catalyst but also maintains a moderate strong interaction between metal Ni-support, thereby promoting the formation of active metal Ni species. Furthermore, the presence of Al leads to an increase in oxygen vacancy concentration, which facilitates the generation of numerous hydroxyl groups. Consequently, this alters the distribution of basic sites on the catalyst surface, resulting in a shift from the CO* pathway to a dual pathway involving both CO* and formate pathways. Remarkably, these divergent reaction pathways correspond to distinct active sites, thereby maximizing the utilization of each region within the catalyst. The diversity of reaction pathways and active sites represents pivotal factors for enhancing the catalytic performance of low-temperature CO2 methanation catalysts.

Ni-Based Catalysts for CO2 Methanation: Exploring the Support Role in Structure-Activity Relationships.

The catalytic hydrogenation of CO2 to methane is one of the highly researched areas for the production of chemical fuels. The activity of catalyst is largely affected by support type and metal-support interaction deriving from the special method during catalyst preparation. Hence, we employed a simple solvothermal technique to synthesize Ni-based catalysts with different supports and studied the support role (CeO2, Al2O3, ZrO2, and La2O3) on structure-activity relationships in CO2 methanation. It is found that catalyst morphology can be altered by only changing the support precursors during synthesis, and therefore their catalytic behaviours were significantly affected. The Ni/Al2O3 with a core-shell morphology prepared herein exhibited a higher activity than the catalyst prepared with a common wet impregnation method. To have a comprehensive understanding for structure-activity relationships, advanced characterization (e. g., synchrotron radiation-based XAS and photoionization mass spectrometry) and in-situ diffuse reflectance infrared Fourier transform spectroscopy experiments were conducted. This research opens an avenue to further delve into the role of support on morphologies that can greatly enhance catalytic activity during CO2 methanation.