Search Results (176)

Electrified steam methane reforming (eSMR) is emerging as a promising technology for the decarbonization of the chemical industry and low-carbon hydrogen production by coupling renewable electricity with renewable gaseous feedstocks such as biomethane. In this work, structured Ni-based catalysts washcoated on highly thermally conductive SiC open-cell foams (OCFs) were developed and evaluated for biomethane steam-reforming operating conditions. Two catalyst formulations, 30 wt.% Al₂O₃_30 wt.% CeO₂_20 wt.%Ni and SiC_30 wt.% Al₂O₃_30 wt.%Ce_0.25Zr0.75 O₂_20 wt.%Ni, were tested in a laboratory-scale indirectly electrically heated reformer. The high thermal conductivity of the SiC-structured support ensured efficient heat transfer throughout the reactor, limiting radial temperature gradients to below 10 °C. Both catalyst formulations exhibited excellent catalytic performance; however, the Ce_0.25Zr0.75O₂-promoted catalyst achieved the best results, maintaining equilibrium methane conversion at a gas hourly space velocity above 7000 h⁻¹ while reaching a specific electrical energy consumption of 2.06 kWh/Nm³ of produced H₂ projected for industrial-scale efficiency. Notably, these performances were obtained with a catalyst loading approximately 20–50% lower than that of conventional commercial alumina pellet catalysts. XRD characterization did not reveal the formation of crystalline graphitic carbon after catalytic operation. Furthermore, the structural evolution of the Ce–Zr–O highlights the active role of the mixed oxide in promoting redox processes and maintaining catalytic activity under reaction conditions. Overall, these results demonstrate that the combination of highly conductive SiC-structured supports and Ce–Zr-promoted Ni catalysts significantly enhances both the thermal and catalytic efficiency of eSMR. The proposed catalyst provides a promising route toward compact, energy-efficient, and decentralized hydrogen production from biomethane, supporting the electrification and decarbonization of future hydrogen generation technologies. Full article

Supported Pt catalysts are highly active for the selective catalytic oxidation of ammonia (NH₃-SCO), but their practical use is limited by poor N₂ selectivity and insufficient hydrothermal durability under high-temperature exhaust conditions. Herein, we report a composition-regulated high-entropy oxide interface strategy to stabilize Pt–Cu dual sites and steer NH₃ oxidation toward selective N₂ formation. A series of fluorite-type Ce-based high-entropy oxides, including CeZrLaPrYO_x, CeSmLaPrYO_x, and CeSnLaPrYO_x, were constructed as thermally robust supports for Pt and Cu loading. Among them, PtCu/HEO-Zr calcined at 1000 °C exhibits the best NH₃-SCO performance, achieving 90% NH₃ conversion at 260 °C while maintaining N₂ selectivity above 80% over a broad temperature window of 100–300 °C under a high weight hourly space velocity of 100,000 mL·g⁻¹·h⁻¹. More importantly, after harsh hydrothermal aging at 800 °C with 10 vol% H₂O for 12 h, the catalyst shows negligible activity loss and nearly unchanged N₂ selectivity, demonstrating exceptional structural and catalytic robustness. Structural and surface analyses reveal that Zr incorporation optimizes the fluorite high-entropy lattice, increases oxygen vacancy concentration, promotes lattice oxygen mobility, strengthens surface acidity, and enriches active Cu²⁺ species, thereby enhancing the interfacial cooperation between NH₃ activation and oxygen-assisted intermediate conversion. In situ DRIFTS further reveals that PtCu/HEO-Zr favors an O_lat-assisted internal selective catalytic reduction pathway, in which adsorbed NH₃ is activated to -NH₂ species and subsequently reacts with lattice oxygen-derived intermediates to form N₂O₂²⁻-like species that decompose into N₂ and H₂O. Meanwhile, the formation of nonselective NO_x and N₂O products is suppressed. This work highlights high-entropy oxide-supported Pt–Cu interfaces as a promising platform for designing hydrothermally durable and N₂-selective NH₃-SCO catalysts. Full article

This review summarizes recent progress in the catalytic conversion of glycerol to glycerol carbonate (GC) via transesterification with alkyl carbonates, a sustainable route for valorizing surplus glycerol from biodiesel production. Emphasis is placed on mixed and promoter-modified metal oxide catalysts, which exhibit high activity, selectivity, and stability due to their tunable balance of basic and Lewis acidic sites. Systems such as Mg-Fe, Mg-Al, Mg-Zr, CaO-CeO₂, and Mg-Ba oxides have achieved over 90% glycerol conversion and 90–96% GC selectivity under mild, often solvent-free conditions. Mechanistic insights, increasingly supported by density functional theory (DFT), reveal that the reaction proceeds via base-assisted glycerol deprotonation, carbonate activation at Lewis acidic centers, and subsequent cyclization to GC. These findings underscore the importance of acid–base cooperation and promoter effects in enhancing turnover frequency, reducing energy barriers, and mitigating catalyst deactivation due to carbonate deposition or leaching. By integrating experimental results with theoretical modelling, this review provides a comprehensive understanding of catalyst design principles, offering guidance for the development of efficient and robust systems for scalable glycerol upgrading. Full article

The activity and stability of Ni-based catalysts for CO₂ methanation strongly depend on the morphology and chemical composition of the support. In this work, Ni catalysts with four oxidic supports (SiO₂, Al₂O₃, CeO₂, ZrO₂) were synthesized via a one-step spray pyrolysis approach. Comprehensive characterization by STEM-EDS, XRD, and N₂ adsorption was used to resolve support morphology, Ni particle size, and nanoparticle incorporation into the support matrix. Beyond steady-state activity and reaction mechanism, the support material also affects the activation period and initial stability of the catalysts. By combining temperature-programmed methanation scans on fresh and spent samples with long-term stability tests, we clearly identify support-dependent changes in initial activity and their correlation with Ni–support interactions. Enhanced physical embedding and stronger chemical binding of Ni nanoparticles significantly reduce activity changes during the first hours on stream. Overall, this study demonstrates that the support and the corresponding metal–support interactions not only affect reaction pathways and activity, but also the pretreatment and activation required to reach a stable operating point, which is of crucial importance in kinetic catalysis research. Full article

The great impact of carbon dioxide emissions on climate change motivates the development of technologies for carbon capture and utilization. CO₂ methanation, which transforms CO₂ into methane using renewable hydrogen, is a promising power-to-gas and carbon utilization pathway. Achieving high activity, strong CH₄ selectivity, and long-term stability remains challenging, as well as pushes to tailor catalyst properties for the methanation reaction. Cerium oxide is therefore widely explored as a support or promoter due to its redox behaviour and oxygen vacancy chemistry. This review surveys recent literature on catalysts based and containing CeO₂ applied for CO₂ methanation, covering not only thermal operation but also non-conventional catalytic routes as photothermal, electrocatalytic, and plasma-assisted, with emphasis on how synthesis and role of Ce tune physicochemical properties and catalytic activity. Across reported systems, dispersing active metals (notably Ni and Ru, Cu for electrochemical systems) on ceria frequently yields to high CH₄ selectivity. Redox properties of ceria enable optimal metal–support interactions and surface basicity to achieve effective CO₂ activation in thermo-catalytic route. Further enhancement of oxygen mobility is associated with doped CeO₂ and solid solutions such as Ce-Zr. The high oxygen storage capacity of CeO₂ promotes photogenerated charge separation for light-driven performance and optimal plasma–catalyst interactions. Full article

Methane combustion over palladium-based catalysts is a critical process for reducing greenhouse gas emissions from lean-burn engines and natural gas installations, yet the role of oxide support in controlling both the population and the intrinsic reactivity of Pd active centres remains incompletely understood. In this work, Pd catalysts at two series of higher and lower loading were prepared on five oxide supports—Al₂O₃, CeO₂, SiO₂, TiO₂, and ZrO₂—and characterised by a complementary suite of techniques including SEM-EDX, XRD, BET, AAS, in situ CO-FTIR, DRIFTS with methanol as a probe molecule, and Raman spectroscopy. Catalytic activity testing revealed the order Pd/CeO₂ > Pd/ZrO₂ > Pd/Al₂O₃ > Pd/TiO₂ > Pd/SiO₂. In situ CO-FTIR site quantification showed that active site density spans nearly an order of magnitude across the series, with Pd/CeO₂ reaching 105.44 µmol g⁻¹ and Pd/Al₂O₃ only 11.63 µmol g⁻¹. Turnover frequency analysis revealed a striking inversion: Pd/Al₂O₃ exhibited the highest TOF (0.1327 s⁻¹), approximately six times greater than Pd/CeO₂ (0.0226 s⁻¹). DRIFTS/methanol profiling demonstrated that CeO₂ and ZrO₂ expose cooperative redox and basic centres that promote methane activation, while SiO₂ supports only weakly bound methoxy species, consistent with its lowest activity. These results establish that the oxide support simultaneously governs Pd dispersion—and hence site density—and the electronic environment of each Pd centre, thereby modulating intrinsic reactivity. High specific surface area alone does not guarantee catalytic performance, and rational support selection is therefore the decisive lever for optimising methane combustion catalysts at ultra-low Pd loadings. In all, our findings provide a quantitative, molecular-level framework that disentangles support-controlled site density from intrinsic site reactivity under identical reaction conditions. By combining in situ CO-FTIR, DRIFTS, and Raman spectroscopy with kinetic analysis on well-defined, high-purity oxide supports, this work transforms previously qualitative “support effects” in Pd-catalysed methane combustion into predictive structure–activity relationships. Full article

This study investigates the influence of isomorphous substitution of Aluminum by V, Zr, La, and Ni in Beta zeolite frameworks used as supports for Ni-based dry reforming of methane catalysts. The research focuses on how the nature of the incorporated metal affects catalytic activity and long-term stability. Catalysts were synthesized using both co-impregnation and sequential impregnation strategies. Physicochemical characterization—including gas adsorption, X-ray diffraction, transmission electron microscopy, and H₂ temperature-programmed reduction—revealed distinct structural roles for each metal. Results indicate that V primarily occupies T-vacancy sites within the dealuminated Beta framework, whereas Ni resides as charge-compensating extra-framework species or highly dispersed NiO clusters. Zr and La tend to form highly dispersed oxide species or occupy enlarged silanol nests. Notably, the addition of La₂O₃ was found to significantly enhance the long-term stability of the catalysts during the dry reforming of methane process. V-modified catalysts exhibited the highest activity but suffered from low stability; conversely, Zr incorporation offered the best overall performance, balancing high activity with enhanced stability, achieving 85% CO₂ and 75% CH₄ conversion, with no detectable carbon deposition after 98 h on stream. Full article

Dry reforming of methane (DRM) converts the greenhouse gases methane (CH₄) and carbon dioxide (CO₂) into syngas (hydrogen (H₂) and carbon monoxide (CO)). Despite its numerous advantages, DRM has not yet been industrialized due to catalyst deactivation and competing side reactions. While Ni-based catalysts have been widely used, they are prone to increased carbon deposition and sintering, and although bimetallic systems and oxygen-based supports have shown promise, their effects on carbon deposition are yet to be fully understood. In this study, carbon nanotube (CNT)-supported Pt-Ni catalysts incorporating mixed oxides of CeZrO₂ and CeZrLaO₂ were investigated to evaluate the impact of support composition and metal–support interactions in DRM. The catalysts were synthesized and subsequently tested in DRM. Catalysts supported on CNTs displayed higher CH₄ and CO₂ conversions compared to conventional ceria–zirconia, highlighting the beneficial role of the carbon nanotube support in improving dispersion and accessibility of the metal active sites. Addition of Pt was found to promote reverse water–gas shift (RWGS) reaction, whereas the addition of La was found to decrease catalytic activity. Despite the formation of a Ni-Pt alloy, the obtained catalysts favored RWGS over DRM. These findings illustrate key limitations and design considerations for optimization of CNT-supported bimetallic catalysts in DRM. Full article

Formaldehyde (HCHO) is a typical volatile organic compound (VOC) that poses significant risks to human health. Long-term exposure, even at low concentrations, has been associated with various malignant diseases, including nasopharyngeal, colon, and brain cancers. Common technologies for HCHO abatement include ventilation, adsorption, photocatalysis, and catalytic oxidation. Among these methods, catalytic oxidation is regarded as the most promising due to its high removal efficiency, low cost, minimal energy consumption, and no toxic by-products. In recent years, supported catalysts with excellent room-temperature activity and high dispersibility have attracted considerable attention. These catalysts can usually be divided into two categories: noble metal catalysts and non-noble metal catalysts. Zirconia (ZrO₂) has become an ideal support owing to its advantages of high specific surface area, abundant and tunable acid–base sites, and strong metal–support interaction (SMSI). Various modification strategies have been developed to improve the catalytic performance of ZrO₂-based systems, such as the construction of phase interfaces and the stabilization of single-atom species. This review summarizes the recent research progress of ZrO₂-based systems for the catalytic oxidation of formaldehyde. It provides a detailed discussion of the physicochemical properties of ZrO₂ supports and the reaction mechanisms involved, and highlights achievements in crystal phase regulation, elemental doping, metal–support interaction, and composite modification. Finally, future challenges and development directions for these catalysts are also outlined. Full article

ALD is a precise thin-film deposition technique based on self-limiting surface reactions. A crucial stage in each ALD cycle is the purge step, which removes excess precursor molecules and reaction by-products from the reactor chamber, preventing uncontrolled gas-phase reactions that could degrade film quality. Despite its fundamental importance, the impact of purge dynamics on film growth and structure remains insufficiently explored. ZnO and ZrO₂ films were deposited in reactors with different effective chamber volumes (47 and 470 cm³), enabling a systematic study of gas residence time effects. Our results demonstrate that the purge mode—dynamic versus static vacuum—strongly affects the growth behavior, crystallinity, and surface morphology of ALD oxides. Dynamic purging leads to smoother, more uniform, and better-crystallized films, whereas static exposure results in lower structural and morphological quality, particularly for ZrO₂. Importantly, these results demonstrate that purge-mode engineering provides a powerful and cost-effective route for tailoring oxide film structure without altering the precursor chemistry or deposition temperature. To validate the practical integration of these optimized films, functional phosphor and LED structures were fabricated, confirming that the controlled microstructure is well-suited for optoelectronic applications. This approach also offers new possibilities for controlling film properties in sensors and catalysts. Full article

This work presents the synthesis, characterization, and application of zirconium oxide (ZrO₂)-based catalysts, modified with macro (silica nanospheres, NSP-SiO₂) and mesopore templates (Pluronic 123), impregnated with tungstophosphoric acid (TPA), in the catalytic pyrolysis of tomato agro-industrial residues. The NSP-SiO₂ (SXX) and P123 (PYY) amount mainly influences the ZrO₂SXXPYY-specific surface area (S_BET) and average pore diameter (D_p). ³¹P MAS NMR and FT-IR characterization results show that TPA (H₃PW₁₂O₄₀) was partially transformed into [P₂W₂₁O₇₁]⁶⁻ and [PW₁₁O₃₉]⁷⁻ during the synthesis steps. The acidic properties of ZrO₂SXXPYY samples containing 25 and 50 wt% of TPA (ZrO₂SXXPYYT25 and ZrO₂SXXPYYT50, respectively) are dependent on both the TPA content and the support nature. Bio-oil composition and product selectivity were strongly influenced by the textural and acid-based properties of the catalysts. Notably, non-catalytic pyrolysis favored pathways leading to C2 compounds, with a high content of acetic acid and hydroxyacetone. In contrast, the use of catalysts promoted the formation of higher molecular weight oxygenated compounds (C5–C6), specifically furans, aldehydes, and ketones. Full article

CO₂ cycloaddition with epoxides offers a sustainable route for CO₂ utilization, yet the simultaneous activation of both substrates remains challenging. Herein, using UiO-66(Zr)-NH₂ (denoted as UZN) as a model system, we illustrate that dual-active sites consisting of unsaturated Zr⁴⁺ centers and amine groups can efficiently accelerate CO₂ fixation with epoxides under visible light. The unique ensemble in UZN optimizes light harvesting, promotes charge carrier separation, and enriches bifunctional active sites for efficient adsorption and activation of epoxides and CO₂. Consequently, UZN exhibits significantly improved CO₂-epoxide cycloaddition performance compared to UiO-66(Zr)-H (denoted as UZH), achieving a PC yield of 99.5%, with a production rate of 9.97 mmol·g⁻¹·h⁻¹. This work establishes a clear coordination–photocatalytic synergy in MOF-based systems and provides fundamental insights and a generalizable strategy for designing advanced catalysts for CO₂ transformation. Full article

This work presents an integrated Python-based framework to optimize the ethanol-to-1,3-butadiene conversion over a K₂O:ZrO₂:ZnO/MgO–SiO₂ catalyst, a sustainable alternative in decarbonizing plastics and rubber manufacturing. Thermodynamic evaluations confirmed the feasibility of all elementary steps, while kinetic modeling identified the butadiene-forming reaction as the most sensitive step. Experimental data were analyzed using multivariate surface-response methods, revealing an optimal operating window of 350–375 °C and 0.93–1.24 h⁻¹. A Random Forest model (R² = 0.91) ranked weight hourly space velocity (WHSV) and selectivity descriptors as the most dominant variables, providing a quantitative basis for data-driven process intensification. Full article

In this work, a rational catalyst design based on interfacial architecture engineering is proposed for low-temperature dry methane reforming (DMR) at 550 °C. Ni-based catalysts containing 10 wt% Ni were developed on a γ-Al₂O₃ support modified with 9 wt% MgO–1 wt% ZrO₂. Zirconia promoters were introduced either by dry impregnation or via an ammonia vapor-assisted route to construct a Ni–NiO–ZrO₂ interfacial network. The effects of ZrO₂ content (0, 1, and 3 wt%) and synthesis route on metal–support interactions, oxygen mobility, and coke resistance were systematically investigated. ZrO₂ promotion increased the fraction of reducible Ni species and preferentially enhanced CO₂ activation, thereby promoting the reverse water–gas shift (RWGS) reaction and lowering the H₂/CO ratio. In contrast, ammonia vapor-assisted preparation induced the formation of an LDH-derived Ni–NiO–ZrO₂ surface network, which increased the concentration of surface-accessible Ni species, suppressed excessive zirconia coverage, and significantly improved apparent oxygen mobility. These synergistic structural features are consistent with enhanced oxygen-assisted carbon removal and improved coke management through regulation of the nature of carbon species, leading to more balanced activation of CH₄ and CO₂. Overall, this study provides insights into interfacial structure–performance relationships for designing efficient Ni-based catalysts for CO₂ utilization. Full article

The hydroisomerization reaction of light alkanes was used to improve their octane value. Industrial light alkane feeds usually contain a certain amount of cycloalkanes and aromatics (known as hydrocarbon impurities). In this study, the influence of hydrocarbon impurities on the isomerization activity of n-alkanes over Pt/SO₄²⁻/ZrO₂/Al₂O₃ (PSZA) was investigated in a continuous flow fixed-bed reactor, TPSR, and pulse reactor. The reason for the influence of hydrocarbon impurities on the isomerization activity of n-alkanes was also discussed by using in situ adsorption–desorption and temperature-programmed reactions. The catalyst was characterized by XRD, PyIR, N₂ adsorption–desorption, TEM, and XRF. The results showed that the prepared catalyst contained mainly tetragonal zirconia and possessed a large amount of strong B and L acid sites. A certain amount of hydrocarbon impurities obviously inhibited the isomerization conversion of n-alkanes. The extent of the inhibition was very dependent on the kind of hydrocarbon impurities, n-alkane carbon number, and reaction temperature. Lighter n-alkane isomerization conversion was influenced to a greater extent. And the increase of reaction temperature could weaken its inhibitory effect. The results provided a reference and base for the industrial application of light alkane hydroisomerization over PSZA. Full article