Ru/NiO-CeO2 nanoparticles supported on Zr-MOFs (UiO-66 and MOF-808) have been prepared and studied for CO2 hydrogenation to CH4, paying special attention to the MOFs stability under reaction conditions. Both supported catalysts were active and selective, and were characterised by means of XRD, N2 physisorption isotherms at-196 degrees C, TEM, XPS and DRIFTS before and after the reaction. The XRD characterization of the fresh and used supported catalysts evidences the gradual degradation of both MOF supports between 200 and 275 degrees C under reaction conditions, which becomes very relevant at 300 degrees C and higher temperatures. Despite this degradation, UiO-66 shows higher stability than MOF-808 under CO2 methanation conditions, which can be attributed to the rigid structure of UiO-66 compared to MOF-808. The large pores and flexibility of MOF-808 seems to weaken the framework under reaction conditions. In situ DRFIT spectra showed that some characteristic bands of UiO-66 are still observed under reaction conditions until 300 degrees C, suggesting that, despite the structural modifications, UiO-66 is not totally degraded but is transformed into a derived solid. This is also in agreement with the only partial decrease of the porosity deduced from N2 adsorption characterization and with the TEM observations. On the contrary, Ru/NiCe/MOF-808 spectra evidence total degradation of this MOF-808 at 300 degrees C.

Ethanol steam reforming (ESR) is a promising pathway for renewable hydrogen production, yet the development of Ni-based catalysts that simultaneously deliver high activity and strong resistance to coke deposition remains a major challenge. This work compares three Ni-CeO2 catalysts synthesized by physical calcination, incipient wetness impregnation, and reverse microemulsion, denoted as Ni-CeO2 (ref), Ni/CeO2 (IW), and Ni-CeO2 (NPs), respectively. Their structure-performance relationships were evaluated to understand how synthesis influences ESR activity and carbon formation. All catalysts follow similar reaction mechanisms (ethoxy dehydrogenation to acetaldehyde, oxidative routes, and direct acetaldehyde decomposition), yet their behavior differs markedly due to structural features. Both Ni/CeO2 (IW) and Ni-CeO2 (NPs) reach high hydrogen production, with yields above 77%. However, the Ni-CeO2 (NPs) catalyst, composed of well-defined nanoparticles and exhibiting the highest concentration of oxygen vacancies, significantly suppresses methane formation and enhances reforming pathways. A key finding is the exceptional coke resistance of the Ni-CeO2 (NPs) material. Post-reaction analyses show substantial carbon accumulation on Ni-CeO2 (ref) and noticeable coke on Ni/CeO2 (IW), whereas Ni-CeO2 (NPs) remains essentially free of carbon deposits even after extended operation. This remarkable stability is attributed to its optimized nanostructure, finely distributed Ni domains, and enhanced redox capacity, which collectively promote continuous surface oxygen availability and hinder the buildup of carbonaceous residues. Overall, the results highlight the crucial role of rational designing Ni-CeO2 catalysts and demonstrate that nanoparticle-engineered materials offer a promising route to achieving highly active, methane-suppressing, and coke-resistant catalysts for sustainable hydrogen production via ESR.

Metallic monolithic substrates are emerging as a next-generation platform for structured catalysts due to their high thermal conductivity, mechanical robustness, and excellent mass-transfer characteristics. Here, metal honeycomb monoliths based on 17–4PH, 316 L, and Inconel 718 alloys were fabricated by fused deposition modeling (FDM)-based metal additive manufacturing (AM) and employed as support for NiO-CeO2 nanoparticulate catalysts in CO2 methanation reaction. Particular emphasis was placed on correlating the microstructural, mechanical, thermal, and corrosion properties of the printed alloys with their suitability as catalytic supports. Although all monoliths exhibited thermal expansion coefficients close to those of fully dense alloys, markedly lower flexural Young's modulus and hardness (HRB) values were obtained because of the residual porosity and microstructural heterogeneity inherent to the FDM printing and sintering route. These results underline the high sensitivity of the mechanical properties to incomplete densification in additively manufactured metals, while still providing sufficient mechanical integrity for catalyst handling, coating and stable operation under the CO2 methanation reaction conditions investigated in this work. H2-TPR, TEM, and XPS analyses confirmed that catalytic behavior was governed by the NiO-CeO2 active phase and remained essentially independent of the metallic substrate, resulting in comparable catalytic activity and methane selectivity among the three alloys. In contrast, accelerated corrosion tests revealed pronounced alloy-dependent durability, with 316 L providing the most favorable balance between oxidation resistance, mechanical stability, and material cost. These results demonstrate the potential of metal additive manufacturing to produce robust and application-oriented catalytic monoliths for CO2 conversion under harsh industrial conditions.

Integrated CO2 capture and methanation using dual-function materials (DFMs) offers a route for the direct conversion of diluted CO2 streams into synthetic methane. In this work, novel DFMs consisting of NiO-CeO2 nanoparticles combined with three-dimensionally ordered macroporous (3DOM) MgO were prepared using a polymethyl methacrylate (PMMA) hard-templating method. The influence of MgO loading and structure on CO2 capture and methanation performance was investigated and compared with a non-templated MgO reference. MgO incorporation increased the CO2 uptake capacity, reaching 120 μmol CO2 g−1 at 200 °C for the 30% 3DOM material, but partially reduced the intrinsic methanation activity of the NiO-CeO2 phase. Nevertheless, the 3DOM architecture outperformed the corresponding reference material at the same MgO loading, demonstrating the beneficial role of the ordered macroporous structure. X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR) showed that MgO does not significantly modify the electronic properties of the NiO-CeO2 nanoparticles. The results show that the balance between CO2 adsorption and catalytic conversion is strongly influenced by the MgO structure, with the 30% 3DOM material providing the best overall compromise between CO2 capture and methanation performance. Integrated capture-methanation performance remained stable over two consecutive cycles. These results highlight the potential of these materials for integrated CO2 capture and methanation applications.

The CO2 methanation reaction mechanism has been studied by isotopic pulse experiments followed by rapid scan DRIFTS-MS and NAP-XPS using synchrotron radiation for mono- and bimetallic Ru/NiO-CeO2 catalysts. CeO2 and NiO-CeO2 (10 % wt. Ni) nanoparticles (NP; 7-8 nm) were prepared by reversed microemulsion, and Ru (1.6 % wt.) was impregnated afterwards. The reaction mechanism starts with the reduction of the catalysts by H2, H2O release and generation of a high population of oxygen vacancies on the catalysts surface where CO2 is evenly chemisorbed and dissociated. The exchange of oxygen atoms between the chemisorbed CO2 molecules and the catalysts occurs simultaneously to the hydrogenation of the carbon intermediates to yield CH4. The most active catalyst (Ru/NiO-CeO2 (NP)) has the best balance between CO2 chemisorption and further hydrogenation of the reaction intermediates. NAP-XPS experiments confirm the redox participation of the Ni2+-CeO2 interface in the chemisorption and dissociation of CO2, and the importance of the Ru0 stability under reaction conditions. Ru/ NiO-CeO2 (NP) combines both features, while Ru0 is not stable and is partially oxidised under reaction conditions on Ru/CeO2 and on a counterpart Ru/NiO-CeO2 catalyst prepared without particle size control. Rapid scan DRIFTS-MS confirms the efficient CO2 chemisorption and fast hydrogenation of the reaction intermediates observed (mainly carbonyls and bicarbonates) on Ru/NiO-CeO2 (NP), while the counterpart catalyst prepared without size control is not able to chemisorb CO2 so efficiently and the Ni-free catalyst is less active for CO2 methanation because the surface carbon species created upon CO2 chemisorption are more difficult to be hydrogenated.

A highly active Ru/NiO-CeO2 (NP) catalyst, synthesized by ruthenium impregnation on NiO-CeO2 mixed oxide 7-8 nm nanoparticles, has been studied for the individual and simultaneous methanation of CO and CO2, showing onset CH4 production in co-methanation at 200 degrees C, and maximum CH4 production at 350 degrees C. Isotopic gas pulse experiments indicated that the catalyst is continuously reduced by H2, yielding catalyst oxygen (16O)-containing water, and it is re-oxidised with 18O once 12C18O or 13C18O2 are pulsed. The catalyst exchanges 16O atoms with the 12C18O and 13C18O2 pulsed gases simultaneously to the hydrogenation to methane. Ru improves the hydrogenation steps and methane production, which is mainly relevant during the CO + CO2 comethanation, and the formation of NiO-CeO2 solid solution improves the COx chemisorption and favors the hydrogenation of the surface carbon reaction intermediates. DRIFTS experiments indicated that chemisorption of CO and CO2 yields the same surface species (bicarbonates and carbonyls), which means that the catalyst dissociates the CO2 molecule to yield carbonyls and it is also able to oxidize CO with catalyst oxygen to yield bicarbonates. NAP-XPS experiments evidenced that the main redox process during the solo CO2 methanation occurs at the Ni2+-CeO2 interface, and that ruthenium is highly and homogeneously reduced, keeping Ru0 stable under reaction conditions. The effect of CO in the oxidation state of the catalyst surface is negligible using pure CO, a CO methanation mixture (CO + H2), and a co-methanation mixture (CO + CO2 + H2), and the reducing effect of H2 always prevails.

The CO2 methanation process in the presence of CO is a catalytic challenge toward the abatement of CO2 emissions from industrial exhaust gases with the goal of producing CH4 as a clean fuel. Herein, the COx methanation mechanisms of a NiO-CeO2 (Np) catalyst constituted by nickel oxide-cerium oxide nanoparticles with efficient operation under CO2 and CO + CO2 gas mixtures were addressed. In situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) analyses and (CO2)-C-13-O-18 (49) pulse isotopic experiments reveal that solo CO2 methanation and comethanation (CO + CO2) present a common mechanism in which CO2 is transformed into *CO, from where the reaction proceeds. According to our outputs, inlet CO interferes with the CO2 methanation activity, delaying the reaction onset without selectivity impacts. Conversely, in the absence of CO2, the solo CO methanation performance is remarkably limited with poor CH4 selectivity. As demonstrated, the solo CO methanation mechanism is based on formates as key intermediates at low temperatures (<250 degrees C), while competitive CO2 production takes place onward. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) analyses conducted in synchrotron revealed a higher degree of reduction in the catalyst when CO and H-2 are fed either alone or in combination with CO2, attributed to the CO oxygen abstraction capacity from the CeO2 phase. In the comethanation mixture, CO2 and CO are balanced in oxidation-reduction processes, yielding the maximum COx conversion, while in the solo CO methanation, reductive processes prevail, limiting the CH4 formation.

Dual function materials based on NiO-CeO2 nanoparticles and MgO supported on beta zeolite have been and tested for direct capture of CO2 from air and further hydrogenation to CH4. Catalysts characterisation highly microporous materials with good dispersion of the NiO-CeO2 active phase on the zeolite carrier slight blockage of zeolite pores. H2-TPR and XPS characterisation reveal that the beta zeolite improves reducibility of the dispersed NiO-CeO2 active phase. Among the synthesis methods tested, impregnation calcination is more convenient than zeolite crystallization in the presence of NiO-CeO2, leading to with higher catalytic activity in the CO2 methanation reaction. On the contrary, the NiO-CeO2 loading effect in the range studied (10, 20 %). The presence of MgO disrupts the intrinsic high catalytic performance NiO-CeO2, but this penalty is not encountered when both MgO and NiO-CeO2 are dispersed on the beta support. CO2 capture from air at 35 degrees C, studied by thermogravimetry, suggests that CO2 chemisorption and NiO-CeO2 prevails with regard to physisorption on beta zeolite. In situ DRIFTS analysis showed mechanism of CO2 adsorption involved carbonate and bicarbonate species and revealed that isolated groups of the beta zeolite can act as CH4 trapping sites. Therefore, the MgO and NiO-CeO2 containing beta catalyst is an adequate dual function material to capture CO2 directly from air and catalyse the hydrogenation the CO2 captured to CH4.

Ni, Ru and CeO2-based bimetallic catalysts have been prepared and studied for low-temperature CO2 methanation, optimizing both the composition and synthesis method. The most active catalyst obtained, with 1.6 % wt. Ru and 10 % wt. Ni, was synthesized by ruthenium impregnation on NiO-CeO2 mixed oxide nanoparticles, which were prepared by reversed microemulsion. The onset reaction temperature is 190 degrees C and yields 26 mu mol CH4 center dot s-1 center dot gcat-1 at 250 degrees C and atmospheric pressure, with 100 % selectivity to CH4, being among the most active reported catalysts at low temperature. The high catalytic activity is attributed to the intimate contact between Ni and Ce cations on solid solution nanoparticles (7-8 nm), which promotes the creation of vacant sites for CO2 chemisorption and dissociation, and further impregnation of ruthenium generates a synergy that facilitates lowtemperature reducibility. In situ DRIFTS experiments confirmed that CeO2 doping with Ni2+ promotes CO2 chemisorption, while ruthenium improves further hydrogenation of the surface carbon species. Isotopic 13C18O2 pulse experiments and NAP-XPS experiments with synchrotron radiation evidence that oxygen from CO2 is retained on the catalyst upon dissociation, and that H2O evolves with catalyst oxygen. The Ce3+/Ce4+ cations play the main role in this oxygen exchange process, Ni2+ improves CeO2 reduction and promotes the creation of oxygen vacancies where CO2 is evenly chemisorbed and dissociated, and ruthenium is highly reduced to metal state under reaction conditions, which explains the effective dissociation of H2 and fast hydrogenation of the surface carbon intermediates.

UiO-66 was synthesized using ZrOCl2.8H2O as metal precursor, and CuO/CeO2/UiO-66 catalysts were prepared and tested for preferential CO oxidation in H2- rich streams (CO-PROX reaction), a reaction of practical significance in hydrogen purification for fuel cells. The study highlights the detrimental effect of residual chlorine anions from UiO-66 synthesis and DMF washing on the catalytic performance of CuO/CeO2/UiO-66. An activation strategy involving rigorous water washing and thermal treatment at 160 degrees C under CO-PROX conditions was developed. Both steps were deemed necessary, as employing only one proved insufficient to reduce chlorine levels to non-poisoning thresholds. This activation procedure does compromise UiO-66 crystallinity and porosity, but it is justified by achieving a fully functional catalyst. TEM images confirm the uniform dispersion of the CuO/ CeO2 active phase on the UiO-66 matrix post-activation and after catalytic testing. A 16-h CO-PROX test at 160 degrees C with the CuO/CeO2/UiO-66 catalyst, once activated, demonstrated stable performance throughout the extended long-term experiment. This research provides valuable insights into optimizing CuO/CeO2/UiO-66 catalysts for CO-PROX application.

Herein, we explore in the catalytic behaviour in the preferential CO oxidation (CO-PROX) reaction of "inverse catalysts" where ceria is dispersed on a copper oxide support. The loadings of CeO2 in the catalysts were optimised and different ceria nanostructures were investigated. Namely, ceria nanoparticles (NP), ceria nanorods (NR), ceria nanocubes (NC), and a polycrystalline reference (RF) were dispersed on a CuOx support. 30% CeO2 was assessed as the optimum load, while bigger and bulky polycrystalline RF particles exhibited the best performance, followed by NR, NC and ultimately, NP. While X-ray photoelectron spectroscopy (XPS) analyses revealed the enhanced surface redox features of 30% RF/CU and 30% NP/CU, CO-PROX in situ diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) and O2(36) pulse isotopic experiments showed that carbonates formed upon CO exposure on CeO2 RF assist in the Mars-van Krevelen CO-PROX mechanism, in contrast to NP, where no carbonates were formed. This study presents a comprehensive investigation of CeO2/CU inverse catalysts for CO-PROX reaction.

Rh/Ce0.9Pr0.1O2/carbon monolith catalysts have been prepared and tested for N2O decomposition, using 3D printing technology to fabricate carbon supports with different channels geometry including conventional honeycomb design and a nonlinear channel of circular interconnections. The potential penalty in pressure drop of the advanced monolith design has been experimentally ruled out. The activity of the supported catalysts has been successfully tested under simulated N2O/He gas flow and in the presence of O2, NOx and H2O simulating the gas composition in an operating room in a hospital and in a nitric acid production plant, removing in both cases the 96 % of N2O at 375 °C and 400 °C respectively. The behaviour of the catalyst with honeycomb support is improved with the advanced support with the 3D network of nonlinear channels of circular interconnections due to the promotion of gas turbulences that diminish gas diffusion limitations generated in the honeycomb channels, allowing conversion increase by 15 %. The stability of the Rh/Ce0.9Pr0.1O2/carbon monolith catalysts was studied by TGA under air flow and the combustion occurred above 435 °C, indicating that the stability window is high enough for the applications tested in this study.The catalysts characterisation indicated that the active phase loaded on the carbon monoliths is located both in the channels where the reaction gases flow through and into the carbon bulk, while the amount located into the carbon bulk generates certain diffusion limitations in the catalytic tests. The accumulation of active phase in the channels is favoured by increasing the active phase loading.

Carbon monolith supports have been manufactured using 3D printed channels template and resorcinol-formaldehyde carbonizable resin. These carbon monoliths were loaded with NiO-CeO2 nanoparticles (Np) as the active phase and tested for CO2 hydrogenation to CH4, focusing on the effect of sealing the carbon porosity with MgO. The MgO coating improves CO2 conversion to CH4 by preventing the NiO-CeO2 nanoparticles from settling within the microporous structure of the carbon support, where gas diffusion limitations hinder access to the active phase. This was confirmed by SEM images, which evidence the introduction of NiO-CeO2 (Np) into the carbon matrix of the bare carbon monolith support and the accumulation of the active phase at the surface of the monolith channels once the porosity is sealed. Other characterization techniques like N-2 adsorption and Hg porosimetry, confirm that the porosity is blocked by MgO. On the other hand, it has been demonstrated that there is not a relevant chemical effect of MgO on the NiO-CeO2 (Np) catalytic performance for the carbon monoliths supported catalysts, because the contact between the MgO and NiO-CeO2 phases is poor due to the dispersing effect of carbon.

Hydrogen, a sustainable and environmentally friendly fuel, can be obtained through the ethanol steam reforming (ESR) process. The most promising catalysts for this process are those based on non-noble metals such as cobalt. The activity, selectivity, and stability of these catalysts strongly depend on the presence of alkali dopants. In this work, we have taken on the challenge of understanding the role of alkali. We synthesized a series of cobalt-containing catalysts supported on alpha-alumina and doped with Na, K, Rb, and Cs, which were thoroughly characterized using spectroscopic and microscopic techniques. We elucidated the significant difference in the efficiency of undoped and alkali-doped catalysts, based on diffuse reflectance infrared Fourier transform (DRIFT) operando spectroscopy studies under ESR conditions. The catalytic test results indicated a strong effect of alkali promoters on the interaction between the acetaldehyde byproduct and the Co/alpha-Al2O3 catalyst surface. Experimental data were confronted with the results of periodic DFT-GGA+U molecular modeling. It has been shown that electron transfer from alkali atoms to the cobalt active phase strongly influences the ethanol reforming pathway by increasing the adsorption energy of the aldehyde intermediate and facilitating the key C-C bond-breaking step.

The present research exploits an innovative methodology for producing auto-pressurized carbon microreactors with a precise and controlled structure analyzing the influence of their design on the fluid dynamics and their catalytic performance. Carbon monoliths with Tesla-valve shape channels (Tesla, T, and modified Tesla, Tm) are synthesized through the combination of 3D printing and sol-gel process and further probed as Ni/CeO2 supports on CO2 methanation. The experimental results and mathematical modeling corroborated the improved performance obtained through the complex design compared to a conventional one. In addition to chaotic fluid flow induced by the deviation in flow direction, which improves the reagents-active phase interaction, local pressure increases due to convergence of flows may enhance the Sabatier reaction according to Le Ch & acirc;telier's principle. Conversely to straight channels, T and Tm are not affected by flow rate and presented chemical control. Tesla-valve with curved angle (Tm) improved the mass transfer, achieving higher conversion and approximate to 30% reaction rate increase regarding right angle (T). Thus, this auto-pressurized multi-stage Tesla-valve monolith opens the gate to design specific and advanced functional materials for multitude chemical reactions where not only the reactant-active phase contact can be maximized but also the reaction conditions can be controlled to maximize the reaction kinetics.

Pressure drop is responsible of a great part of the energy cost in industry due the energy consumed by pumps driving a fluid through the installation, and heterogeneous catalysis industrial processes suffer from this pressure drop penalty. This study demonstrates that UiO-66 significantly improves the catalytic performance of the CuO/CeO2 active phase for preferential CO oxidation in H-2 streams with regard to a conventional gamma-Al2O3 carrier due to the particular porous and crystalline properties of MOF materials. A packed bed of UiO-66 produces very low-pressure drop in comparison to conventional catalytic carriers, such as gamma-Al2O3 or beta zeolite, being 4 times lower for UiO-66 than for gamma-Al2O3 under 2 L/min flow of N-2, and this ratio increases and approaches infinity for lower gas flow rates. This feature of UiO-66 not only decreases the energy required to pump gases through the catalytic bed, but also improves catalytic performance of UiO-66-supported catalysts due to the enhanced gas diffusion into the catalytic bed. The reaction gases flow through the interparticle space left by the catalyst in a packed bed of CuO/CeO2/gamma-Al2O3, and this produces high pressure drop, preferential gas pathways and mass transport limitations, negatively affecting the reaction rate. On the contrary, the reaction gases are able to flow through the UiO-66 material without channel constrictions, and the CuO/CeO2/UiO-66 catalysts avoid the gas diffusion restrictions of conventional catalysts.

7‐Azaindole has been integrated as building block with complementary N‐H···N hydrogen bonding sites for the synthesis of a tetrahedral molecular tecton, namely tetra(α‐carbolin‐6‐yl)methane, TACM. The self‐assembly of this molecule results in a 3D hydrogen‐bonded organic framework (HOF). This supramolecular structure constitutes a crystalline microporous material with an extraordinary thermal and chemical robustness. Single crystal X‐ray diffraction reveals how the five‐fold catenation of diamonoid systems, stabilized by hydrogen bonds and π‐π interactions, form an interpenetrated network with monodimensional channels. The structural features of the crystalline material are also observed by transmission electron microscopy (TEM). Additionally, the microporosity of the activated TACM‐HOF is characterized by gas sorption (N2, CO2, CH4 and H2) experiments performed at different pressures. A selective adsorption is observed for CO2 uptake and TACM‐HOF also presents a good adsorption capacity for H2 among supramolecular organic frameworks.

Pressure drop is responsible of a great part of the energy cost in industry due the energy consumed by pumps driving a fluid through the installation, and heterogeneous catalysis industrial processes suffer from this pressure drop penalty. This study demonstrates that UiO66 significantly improves the catalytic performance of the CuO/CeO2 active phase for preferential CO oxidation in H2 streams with regard to a conventional g-Al2O3 carrier due to the particular porous and crystalline properties of MOF materials. A packed bed of UiO66 produces very low-pressure drop in comparison to conventional catalytic carriers, such as g-Al2O3 or beta zeolite, being 4 times lower for UiO66 than for g-Al2O3 under 2 L/min flow of N2, and this ratio increases and approaches ∞ for lower gas flow rates. This feature of UiO66 not only decreases the energy required to pump gases through the catalytic bed, but also improves catalytic performance of UiO66-supported catalysts due to the enhanced gas diffusion into the catalytic bed. The reaction gases flow through the interparticle space left by the catalyst in a packed bed of CuO/CeO2/g-Al2O3, and this produces high pressure drop, preferential gas pathways and mass transport limitations, negatively affecting the reaction rate. On the contrary, the reaction gases are able to flow through the UiO66 material without channel constrictions, and the CuO/CeO2/UiO66 catalysts avoid the gas diffusion restrictions of conventional catalysts.

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.