Activity For CO2 Methanation Research Articles

Ni–CaZrO3 with perovskite phase loaded on ZrO2 for CO2 methanation

CO2 methanation has emerged as a promising strategy for the greenhouse gas CO2 utilization and storage of hydrogen. However, achieving low temperature activity and high temperature stability remains challenging due to the sintering of Ni-based catalysts. To address these limitations, this study introduces a Ni–CaZrO3 catalyst featuring a perovskite phase supported on ZrO2, prepared via citrate complexation and impregnation methods. In this approach, a perovskite-type oxide (PTO) of CaZrO3 forms through a solid reaction on the surface of ZrO2 with impregnated CaO. The formation of CaZrO3 on Ni/ZrO2 restrains the ZrO2 support aggregation and reduces the particle size of Ni nanoparticles (NPs), thereby enhancing the activity for CO2 methanation. The interaction between Ni–CaZrO3, and ZrO2 effectively confines the Ni NPs and CaZrO3, enhancing the sintering resistance of Ni–CaZrO3. This leads to excellent stability of the resulting catalyst for CO2 methanation. The Ni–CaZrO3/ZrO2 catalyst achieves 85% CO2 conversion and maintains 100% methane selectivity at 300 °C, demonstrating the prolonged stability over 100 h at 550 °C. Notably, the loading of CaZrO3 in a perovskite phase on ZrO2 via solid surface reaction represents an interesting and valuable route, which could be extended to loading other PTOs for industrial applications.

Significant low-temperature activity of tetragonal-type ZrO2-supported Ru catalysts for CO2 methanation

Abstract Conversion of CO2 with H2 to CH4 is a potential route for the utilization of CO2. Because CO2 methanation is an exothermic reaction, the equilibrium yield decreases with increasing temperature. A catalyst that exhibits high activity at low temperatures is thus highly desirable. We report here that a tetragonal-type ZrO2-supported Ru catalyst prepared by low-temperature calcination showed significant low-temperature activity for CO2 methanation. We surmise that an intermediate formate species formed over the tetragonal-type ZrO2 and enhanced the catalytic activity.

Performance of supported Co3O4 catalysts in the preferential oxidation of carbon monoxide: Effect of support type and synthesis method

This study investigated the performance of supported Co3O4 catalysts during the preferential oxidation of carbon monoxide (CO-PrOx) in a H2-rich environment, focusing on the effects of different catalyst synthesis methods, namely, wetness impregnation (WI) and solution combustion synthesis (SCS), and different support materials, namely, Al2O3 and SiC. During CO-PrOx, the SiC-supported Co3O4 catalysts attained higher CO2 yields when compared with the Al2O3-supported Co3O4 catalysts possibly because of the existence of weaker interactions between Co3O4 and SiC. Moreover, the catalysts prepared via SCS achieved higher CO2 yields than the catalysts prepared via WI likely due to the presence of smaller and well-dispersed Co3O4 particles in the SCS-prepared catalysts. Significantly high amounts of unwanted CH4 were produced over the SiC-supported catalysts between 225 and 250 °C. The high CO methanation activity was also attributed to the weaker Co3O4-SiC interactions, which enabled the easier reduction of Co3O4 to methanation active metallic Co.

CO2 methanation on Ni/Y2O3 Catalysts: The effects of preparation procedure and cerium oxide promotion

Present paper reports on the CO2 methanation (CME) performance of novel Ni catalysts supported on yttria, ceria, and ceria-doped yttria carriers. Catalysts were synthesized using incipient wetness impregnation and precursor nitrate co-decomposition. These systems outperformed on a mass-specific basis an industrial Ni/alumina benchmark catalyst. In addition, this work examines in details the impact of both the preparation procedure and the Ni-content on the CME activity both in terms of the reaction rate and the apparent activation energy. Our research demonstrates that Y2O3 is an effective catalytic support promoting stability and activity of the catalysts. CeO2–doping further improves activity, remarkably with little to no penalty to the thermal stability of the catalysts. Comparison of the performance of a conventional IWI-synthesized Ni-catalyst with a counterpart obtained via a co-decomposition route, demonstrated an advantage of the latter. Our findings suggest Ni-CeO2/Y2O3 prepared via co-decomposition may be advised as the active and stable catalysts for CME applications.

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.

NiAlFe catalysts based on hydrotalcite-like precursors for low temperature CO2 methanation: Electronic effects among components and intrinsic activity of Ni site

NiAlFe catalysts based on the hydrotalcite-like precursor were prepared and the catalysts exhibit excellent low temperature catalytic activity for CO2 methanation. CO2 conversion over the NiAlFe0.3 catalyst is nearly 80 % under the condition of T = 225 °C, P = 1 atm, and WHSV = 24000 mL/(g∙h). With the increase in the substitution of Fe for Al, the hydrotalcite-like structure of the catalyst precursor is gradually destroyed; the reducibility of NiO component is promoted; the amount of surface basic site decreases. There is a strong electronic push–pull effect between NiO and Al2O3 in the calcined catalyst, and the electronic effect is weakened with the introduction of Fe because Fe3+ shares the responsibility of Ni2+ for donating electron to Al3+. In the reduced catalysts, the Ni3Fe alloy was formed and the electrons are pushed from Ni0 to Fe0. With the increase in the Fe amount, the number of surface Ni atom decreases, while the intrinsic activity of Ni active site enhances. The number and intrinsic activity of Ni site are the main two factors determining the CO2 methanation activity at low temperature. Moreover, the substitution of Al3+ by Fe3+ is beneficial for the stability of the catalysts by inhibiting the agglomeration of catalyst particle.

Enhanced low-temperature activity of CO2 methanation over Ni/CeO2 catalyst: Influence of preparation methods

Enhanced low-temperature activity of CO2 methanation over Ni/CeO2 catalyst: Influence of preparation methods

Boosting CO2 methanation activity by tuning Ni crystal plane and oxygen vacancy in Ni/CeO2 catalyst

It is challenging to boost CO2 methanation activity over Ni-based catalysts, and new findings that decipher the relationship between the essential laws of catalysts and their catalytic performance will be transformative. Herein, three kinds of Ni/CeO2 catalysts with different Ni crystal facets and oxygen vacancy are developed by varied preparation methods, which show significant differences in catalytic performance for CO2 methanation, and these catalysts are taken as a case study for the investigation of the crystal plane and oxygen vacancy effects in CO2 methanation as well. It is observed that the activity of Ni/CeO2-SG catalyst with abundant oxygen vacancies and principally exposed Ni (111) crystal facet is highly active for CO2 methanation reaction, which is 1–3 times than that of Ni/CeO2 catalysts with poor oxygen vacancy and/or Ni (111) crystal face. In addition, the former one cannot suffer from deactivation even in operation 130 h at 300 °C. Both structural investigations and catalytic evaluations indicate that the adsorption and activating ability of H2 and CO2 can be controlled by adjusting the Ni-exposed crystal face and oxygen vacancy concentration, respectively. It is also verified that the synergistic contribution of the Ni crystal facets and the oxygen vacancy play a crucial role in boosting the catalytic activity of the Ni/CeO2 catalysts by affecting the adsorption and activation of reactants. The Ni/CeO2 catalysts exposed Ni (111) crystal plane facilitate the catalytic activity by strengthing the H2 adsorption/dissociation capacity, while the abundantly available oxygen vacancies maximize the activity via acting as CO2 activation sites. Furthermore, the in situ DRIFT experiments reveal that the direct formate hydrogenation pathway is involved in the CO2 methanation process over the Ni/CeO2-SG catalyst.

Enhancement of catalytic activity in CO2 methanation in Ni-based catalysts supported on delaminated ITQ-6 zeolite

Ni-based catalysts supported on delaminated ITQ-6 zeolite with different Si/Al ratios, 30 and ∞, were tested in the methanation of CO2 and CO. ITQ-6 supports exhibited high surface areas (> 590 m2/g), and the catalysts based on them presented elevated CO2 and CO conversion values, turnover frequencies (TOF), and CH4 selectivity (> 90 %). Comparing the ITQ-6 catalyst and its precursor ferrierite (FER)-based catalyst, H2-chemisorption results confirmed higher metallic dispersion for the former, which resulted in improved H2 uptake and efficient interaction of reaction intermediates via the associative pathway. Combined kinetic studies indicated that their higher available metallic surface contributed to lower apparent activation energies towards CH4 formation, accounting for the higher selectivity values. A 15 wt% Ni-based catalyst supported on ITQ-6 zeolite (Si/Al = 30) exhibited catalytic results (XCO2 = 79 % y SCH4 = 98 %) comparable or even superior to some of the best zeolite-based catalysts reported so far.

Facile synthesis of Ni-phyllosilicate assisted by polyacrylamide at room temperature for CO2 hydrogenation to methane

To elucidate the effect of solution viscosity on the synthesis of Ni-phyllosilicate, polyacrylamide was incorporated to create a viscous aqueous medium containing of sodium metasilicate, nickel nitrate and NH4F. The enhanced viscosity promotes the dispersion of the initial formed crystal seeds and the growth of Ni-phyllosilicate, culminating in a Ni-rich NiPs-RT-6 of a high Ni content of up to 55.2 wt%. Residual polyacrylamide elimination was accomplished via calcination, concurrently enhancing metal-support interaction. The as-synthesized samples display a nanoflower morphology with nanospheres overlaid with numerous thin nanosheets. The relatively small Ni particles around 5.7 nm were obtained after reduction even at a very high Ni loading, owing to its strong metal-support interaction. NiPs-RT-6 achieves a CO2 conversion of 75.9% at 450 °C, 0.1 MPa, 60 L g−1·h−1, which closely approximates thermodynamic equilibrium. The turn over frequency for CO2 (TOFCO2) was substantial, calculated at 3.7 × 10−3 s−1, accompanied by activation energy (Ea) of 80.6 kJ·mol–1. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) further disclosed that m-HCOO– serves as a crucial intermediate following a formate reaction pathway. With its high Ni content, finely distributed Ni particles, and strong metal-support interaction, NiPs-RT-6 demonstrates promising catalytic activity in 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).

Enhanced CO2 methanation activity of Ni-Rutile-based catalyst by tuning the metal−support interaction with Fe doping

CO2 methanation is an effective way for CO2 recycling, and nickel-based catalysts have attracted much attention in this field due to their excellent CH4 selectivity and cost-effectiveness; however, their applications are limited by their suboptimal catalytic activity. In this work, the catalytic activity of Ni-rutile-based catalysts was increased by almost an order of magnitude simply by doping the rutile with Fe. Series characterizations show that three factors that mainly contributed to the improved catalytic performance of the Ni/Fe-Rutile, which are the reduction of the Ni size, the increase of the basic sites, and the inhibition of the encapsulation of the Ni particles by the support. With Fe doping, the OH and oxygen vacancies on the rutile surface were reduced, which made the support difficult to reduce and thus suppressed the encapsulation of Ni by the support. As a result, the number of exposed active sites on the Ni/Fe-Rutile which with a smaller Ni size was further successfully increased, and the catalytic activity was significantly improved. This study provides new ideas for the design of activity-enhanced supported catalysts from the perspective of tuning the metal-support interaction and may be applicable to other reducible oxide-supported metal catalysts.

Plasma‐catalytic CO2 methanation over NiO/bentonite catalysts prepared by solution combustion synthesis

AbstractA solution combustion synthesis (SCS) process to prepare nickel catalyst over bentonite (NiO/Ben) is reported. Compared to the traditional impregnation method, NiO/ben produced by SCS has smaller nickel particle size and higher dispersion. With a metal loading of 20 wt%, the afforded NiO/Ben demonstrates excellent catalytic activity for CO2 methanation in a dielectric barrier discharge reactor. In certain discharge conditions (H2:CO2 ratio of 5 in feed gas, discharge input power of 45 W, and gas hourly space velocity of 11 320 h−1), CO2 conversion and CH4 selectivity are as high as 55.8% and 84.6%, respectively. Under the conditions of plasma configuration, the strong interaction between the nickel species and the support plays an important role in the CO2 methanation process.

Construction of multi-porous Ni-based monolithic catalyst by combining wood carbon and SBA-15 for strengthening CO2 methanation

Monolithic catalysts meet the needs of practical application compared with powder catalysts. In this work, we constructed a Ni-based monolithic catalyst (Ni/SAB-15/WWC) by in situ growth of rod-like mesoporous SBA-15 in the microchannels of wood carbon. The small Ni-based nanoparticles (∼5.3 nm) were uniformly dispersed into the mesoporous channels via a post-loading method. The monolithic Ni/SAB-15/WWC catalyst with a multilevel porous structure could provide a laminar gas flow on the surface of Ni active sites, increasing the low-temperature activity and high-temperature durability of CO2 methanation. The Ni/SAB-15/WWC with low Ni loading (∼2%) displayed superior CO2 methanation catalytic performance in terms of low-temperature activity and CH4 selectivity compared with the powder Ni/SAB-15 with high Ni loading (∼15 %). The combination of wood carbon and mesoporous materials is an innovative strategy for the design monolithic catalysts with low metal loading and excellent catalytic performance.

Enhanced CO2 methanation activity over Ni/CeO2 catalyst by adjusting metal-support interactions

CO2 methanation is an essential means of utilizing CO2, which is crucial to solving environmental problems and alleviating energy crisis. The design and development of high- performance low temperature CO2 methanation catalysts is the key to its further application. In this work, the metal-support interaction of Ni/CeO2 catalyst was regulated by changing the calcination temperature and Ni loadings to optimize the CO2 methanation performance. The results showed that 5NiCe-800 exhibited the best CO2 conversion of 83.1 % and 98.0 % CH4 selectivity at 350 °C, since it has a suitable Ni-CeO2 interaction, higher oxygen vacancy concentration, great reducibility and better basic site distribution. The reaction mechanism and the synergistic effect of CeO2 and Ni in CO2 methanation was revealed by in-situ FTIR, which is of great significance for the development of efficient CeO2 supported Ni-based for CO2 methanation.

Impact of varied zeolite materials on nickel catalysts in CO2 methanation

Ni catalysts supported on 4A, 5A, 13X, ZSM-5, and BEA zeolites were prepared using the vacuum-heating method for CO2 methanation. These support materials play a pivotal role in shaping the catalysts' properties and their catalytic performance. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mappings suggest a significant concentration of Ni nanoparticles situated on the external surfaces of catalysts with low Si/Al ratios zeolites (Ni-4A, Ni-5A, and Ni-13X). These Ni nanoparticles exhibit characteristics of weaker metal-support interaction, lower metal reduction temperatures, and moderate H2 adsorption activity. Moreover, these low Si/Al ratio zeolites demonstrate robust CO2 adsorption activity. These properties endow Ni-5A and Ni-13X catalysts with heightened CO2 conversion (70.4–70.9%) and methane selectivity (92.4–96.4%). In contrast, high Si/Al ratio zeolite-based catalysts (Ni-ZSM-5 and Ni-BEA) exhibit smaller Ni particles, strong metal-support interaction and weaker CO2 adsorption activity, resulting in reduced CO2 methanation activity and decreased methane selectivity (71.2–73.4%). The normalized CO2 conversion rate presents a correlation with the average Ni particle size.

Structural design and particle size examination on NiO-CeO2 catalysts supported on 3D-printed carbon monoliths for CO2 methanation

3D-printed high-surface carbon monoliths have been fabricated and tested as catalyst supports of CO2 methanation active phases (NiO-CeO2, 12 wt% Ni). The carbon carriers show a developed microporosity and good adherence to the catalytic phases of NiO-CeO2, showing great stability and cyclability. Two monolith designs were used: a conventional parallel-channeled structure (honeycomb) and a complex 3D network of non-linear channels built upon interconnected circular sections (circles), where flow turbulences along the reactant gas path are spurred. The effect of the active phases particle size on the catalyst distribution and the overall performance has been assessed by comparing NiO-CeO2 nanoparticles of 7 nm average (Np), with a reference counterpart of uncontrolled structure (Ref). The improved radial gases diffusion in the circles monolith design is confirmed, and nanoparticles show enhanced CO2 methanation activity than the uncontrolled-size active phase at low temperatures (< 300 ºC). On the contrary, the Ref catalysts achieve higher CH4 production at higher temperatures, where the reaction kinetics is controlled by mass transfer limitations (T > 300 ºC). SEM and Hg porosimetry evidence that nanoparticles are deposited at deeper penetration through the narrow micropores of the carbon matrix of the monolithic supports, which tend to accumulate on the channels surface remaining more accessible to the reactant molecules. Altogether, this study examines the impact of the channel tortuosity and the active phase sizing on the CO2 methanation activity, serving as ground knowledge for the further rational and scalable fabrication of carbon monolith for catalytic applications.

Effects of Ru particle size over TiO2 on the catalytic performance of CO2 hydrogenation

The influence of metal particle size over heterogeneous catalysts on the catalytic performance has always been an interesting subject due to its significance from both fundamental and practical perspectives. In this work, we regulated the synthesis of TiO2 by the hydrolysis of different titanium precursors, and as-prepared TiO2 supports were employed to load Ru with impregnation method. Interestingly, we synthesized three Ru-TiO2 catalysts with different Ru particle sizes of 1.1, 2.9 and 5.2 nm. The Ru-TiO2 catalysts were next tested for CO2 hydrogenation reaction, the results show that the medium Ru particles on TiO2 exhibited the best CO2 methanation activity. Based on the characterizations, we observed that the medium Ru particles exhibited the best redox properties compared with small and large Ru particles, which was beneficial to the H2 dissociation; in addition, the medium Ru particles exhibited a moderate ability to activate CO2, resulting in the most favorable formation and decomposition of bidentate bicarbonate. Consequently, the Ru-TiO2 catalyst with medium Ru particles showed the highest activity for CO2 methanation. This study provides a new method to prepare Ru-TiO2 catalysts with different Ru sizes and also presents an understanding of Ru particle size effects on CO2 hydrogenation.

Lattice capacity-dependent activity for CO2 methanation: crafting Ni/CeO2 catalysts with outstanding performance at low temperatures.

In the pursuit of understanding lattice capacity threshold effects of oxide solid solutions for their supported Ni catalysts, a series of Ca2+-doped CeO2 solid solutions with 10 wt% Ni loading (named Ni/CaxCe1-xOy) was prepared using a sol-gel method and used for CO2 methanation. The lattice capacity of Ca2+ in the lattice of CeO2 was firstly determined by the XRD extrapolation method, corresponding to a Ca/(Ca + Ce) molar ratio of 11%. When the amount of Ca2+ in the CaxCe1-xOy supports was close to the CeO2 lattice capacity for Ca2+ incorporation, the obtained Ni/Ca0.1Ce0.9Oy catalyst possessed the optimal intrinsic activity for CO2 methanation. XPS, Raman spectroscopy, EPR and CO2-TPD analyses revealed the largest amount of highly active moderate-strength alkaline centers generated by oxygen vacancies. The catalytic reaction mechanisms were revealed using in situ IR analysis. The results clearly demonstrated that the structure and reactivity of the Ni/CaxCe1-xOy catalyst exhibited the lattice capacity threshold effect. The findings offer a new venue for developing highly efficient oxide-supported Ni catalysts for low-temperature CO2 methanation reaction and enabling efficient catalyst screening.

Electronic regulation of MoS2 edge sites by d electron transfer of Ni or Co to improve the activity of CO sulfur-resistant methanation

The catalyst modified by the difference of transition metal d orbital electrons is a promising strategy to promote its catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, Ni and Co transition metals were used to modify the MoS2 catalyst and promote activity for sulfur-resistant CO methanation. Characterization results indicated that Ni or Co atoms could be successfully doped into the edge-site of MoS2, which generated more S-vacancy at Mo-edge site and enhanced sulfur-resistant CO methanation activity. The roles of Ni and Co doping in improving activity were explored based on DFT calculation. It was found that Ni or Co could modify the electronic structure, weaken the strength of their interaction with edge S atoms and promote the spontaneous formation of more S vacancies at Mo edge sites. This leads to enhancing the adsorption of CO and weakening the bonding energy between C-O, which implied the facilitation of CO hydrogenation. Moreover, the modified Ni(Co)-Mo-S active sites facilitate the rate-determining step of CO hydrogenation activation to form *CHO species, which contributes to the enhanced activity for sulfur-resistant CO methanation. This work provides an attractive method for modifying MoS2 catalysts for sulfur-resistant CO methanation.