Deactivation Issues Research Articles

Low-Temperature Activation and Coupling of Methane on MgO Nanostructures Embedded in Cu2O/Cu(111).

The efficient conversion of methane into valuable hydrocarbons, such as ethane and ethylene, at relatively low temperatures without deactivation issues is crucial for advancing sustainable energy solutions. Herein, AP-XPS and STM studies show that MgO nanostructures (0.2-0.5 nm wide, 0.4-0.6 Å high) embedded in a Cu2O/Cu(111) substrate activate methane at room temperature, mainly dissociating it into CHx (x = 2 or 3) and H adatoms, with minimal conversion to C adatoms. These MgO nanostructures in contact with Cu2O/Cu(111) enable C-C coupling into ethane and ethylene at 500 K, a significantly lower temperature than that required for bulk MgO catalysts (>700 K), with negligible carbon deposition and no deactivation. DFT calculations corroborate these experimental findings. The CH4,gas → *CH3 + *H reaction is a downhill process on MgO/Cu2O/Cu(111) surfaces. The activation of methane is facilitated by electron transfer from copper to MgO and the existence of Mg and O atoms with a low coordination number in the oxide nanostructures. The formation of O-CH3 and O-H bonds overcomes the energy necessary for the cleavage of a C-H bond in methane. DFT studies reveal that smaller Mg2O2 model clusters provide stronger binding and lower activation barriers for C-H dissociation in CH4, while larger Mg3O3 clusters promote C-C coupling due to weaker *CH3 binding. All of these results emphasize the importance of size when optimizing the catalytic performance of MgO nanostructures in the selective conversion of methane.

Efficient propane dehydrogenation catalyzed by Ru nanoparticles anchored on a porous nitrogen-doped carbon matrix

Propane dehydrogenation (PDH) is a vital industrial process for producing propene, utilizing primarily Cr-based or Pt-based catalysts. These catalysts often suffer from challenges such as the toxicity of Cr, the high costs of noble metals like Pt, and deactivation issues due to sintering or coke formation at elevated temperatures. We introduce an exceptional Ru-based catalyst, Ru nanoparticles anchored on a nitrogen-doped carbon matrix (Ru@NC), which achieves a propane conversion rate of 32.2% and a propene selectivity of 93.1% at 550 °C, with minimal coke deposition and a low deactivation rate of 0.0065 h−1. Characterizations using techniques like TEM and XPS, along with carefully-designed controlled experiments, reveal that the notable performance of Ru@NC stems from the modified electronic state of Ru by nitrogen dopant and the microporous nature of the matrix, positioning it as a top contender among state-of-the-art PDH catalysts.

The effect of hydrothermal pretreatment on the catalytic performance of Zn/HZSM-5 catalysts for ethylene aromatization reaction

To address the issue of coking and deactivation of Zn/HZSM-5 catalysts used for lightolefins aromatization, a high-temperature hydrothermalmethod was employed for catalyst pretreatment. The catalysts were characterized using XRD, N2 physical adsorption-desorption, NH3-TPD, Py-FTIR, XPS, and TG techniques. The effect of high-temperaturehydrothermal pretreatment on the catalytic performance and stability of the catalyst was investigated using ethylene aromatization as a probe reaction. The results showed that the Zn/HZSM-5 catalyst exhibited excellent catalytic performance after48 h of high-temperature hydrothermal pretreatment. Although the conversion of ethylene slightly decreased, the catalyst lifetime was significantly extended, increasing from 72to 216 h, while the aromatics selectivity remained above 60%. It was suggested that the hydrothermal treatment enhanced the interaction between ZnO species and Brønsted acid sites, promoting the generation of ZnOH+ species. This not only suppressed the hydrogen transfer reaction but also significantly enhanced the dehydrogenation performance of the catalyst, improving the selectivity towards hydrogen. Additionally, the catalyst exhibited increased carbon capacity and reduced carbon deposition rate after hydrothermal treatment, demonstrating excellent anti-coking properties.

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis.

Zeolites are crystalline aluminosilicates with well-defined microporous structures that have found several applications in catalysis. In recent years, great effort has been devoted to defining strategies aimed at tuning structural and acidity properties to improve the catalytic performance of zeolites. Depending on the zeolitic structure, the acid sites located inside the crystals catalyze reactions by exploiting the internal channel shape-selectivity. In contrast, strong acid sites located on the external surface do not offer the possibility to control the size of molecules involved in the reactions. This aspect generally leads to a loss of selectivity toward desired products and to the uncontrolled production of coke. Passivating surface acidity is a promising way to overcome deactivation issues and to enhance the catalytic performance of zeolites. This Mini-Review aims to provide, for the first time, a complete overview of the techniques employed in recent years to neutralize strong external acid sites. Both chemical and liquid vapor deposition of silicates have been widely employed to passivate the external surface acidity of zeolites. In recent years, the epitaxial growth of layers of aluminum-free zeolite, e.g., silicalite-1, over the surface of the acidic zeolite has been proposed as a new approach to neutralize strong external acid sites controlling diffusional phenomena. NH3-TPD, FT-IR, SEM-EDX, and other techniques have been used to provide information about the level of control of the external strong acidity of passivated zeolites. In this Mini-Review, both passivation treatments and characterization techniques are compared and advantages and disadvantages deeply discussed to elucidate the effect of passivation procedures on physical features and especially the catalytic behavior.

Design of earth-abundant Ni3ZnC0.7@Ni@C catalyst for selective butadiene hydrogenation

The pursuit of developing catalysts from earth-abundant materials to supplant those based on precious metals is of paramount importance in selective hydrogenations. While nickel-based systems have shown promise in the selective hydrogenation of butadiene, their practical applications are hampered by severe deactivation issues due to coke deposition and excessive hydrogenation. Here, a novel catalyst, Ni3ZnC0.7@Ni@C, is ingeniously engineered through the controlled oxidation of Ni3ZnC0.7@C. This catalyst is characterized by small Ni0 ensembles elegantly embellishing the Ni3ZnC0.7 nanoparticles, all encased within porous carbon shells. The evolutions of this catalyst, in terms of composition and structure during the oxidation process, is meticulously observed and characterized using a spectrum of advanced techniques. The Ni3ZnC0.7@Ni@C catalyst exhibits outstanding activity and stability in the hydrogenation of butadiene, surpassing other Ni-based systems, including its precursor Ni3ZnC0.7@C and other previously documented catalysts such as Ni3InC0.5 and the Ni3In alloy. A pivotal finding of this research is the self-limiting behavior of coke deposition in the initial reaction stages. This intriguing phenomenon not only curbs further deactivation but also significantly enhances butene production, maintaining operational stability for an impressive duration of 80 hours. This discovery underscores the advantageous role of in situ generated ‘soft’ cokes in augmenting the selectivity and stability of the catalyst, which is particularly enlightening for other catalytic processes that are similarly afflicted by coking issues, thereby opening avenues for further in-depth investigations in this field.

Tailoring the A and B site of Fe-based perovskites for high selectivity in the reverse water-gas shift reaction

The reverse water-gas shift reaction (rWGS) is of particular interest as it is the first step to producing high-added-value products from carbon dioxide (CO2) and renewable hydrogen (H2), such as synthetic fuels or other chemical building blocks (e.g. methanol) through a modified Fischer-Tropsch process. However, side reactions and material deactivation issues, depending on the conditions used, still make it challenging. Efforts have been put into developing and improving scalable catalysts that can deliver high selectivity while at the same time being able to avoid deactivation through high temperature sintering and/or carbon deposition. Here we design a set of perovskite ferrites specifically tailored to the hydrogenation of CO2 via the reverse water-gas shift reaction. We tailor the oxygen vacancies, proven to play a major role in the process, by partially substituting the primary A-site element (Barium, Ba) with Praseodymium (Pr) and Samarium (Sm), and also dope the B-site with a small amount of Nickel (Ni). We also take advantage of the exsolution process and manage to produce highly selective Fe-Ni alloys that suppress the formation of any by-products, leading to up to 100% CO selectivity.

In Situ Reconstruction of Active Heterointerface for Hydrocarbon Combustion through Thermal Aging over Strontium-Modified Co3O4 Nanocatalyst with Good Sintering Resistance.

The issue of catalyst deactivation due to sintering has gained significant attention alongside the rapid advancement of thermal catalysts. In this work, a simple Sr modification strategy was applied to achieve highly active Co3O4-based nanocatalyst for catalytic combustion of hydrocarbons with excellent antisintering feature. With the Co1Sr0.3 catalyst achieving a 90% propane conversion temperature (T90) of only 289 °C at a w8 hly space velocity of 60,000 mL·g-1·h-1, 24 °C lower than that of pure Co3O4. Moreover, the sintering resistance of Co3O4 catalysts was greatly improved by SrCO3 modification, and the T90 over Co1Sr0.3 just increased from 289 to 337 °C after thermal aging at 750 °C for 100 h, while that over pure Co3O4 catalysts increased from 313 to 412 °C. Through strontium modification, a certain amount of SrCO3 was introduced on the Co3O4 catalyst, which can serve as a physical barrier during the thermal aging process and further formation of Sr-Co perovskite nanocrystals, thus preventing the aggregation growth of Co3O4 nanocrystals and generating new active SrCoO2.52-Co3O4 heterointerface. In addition, propane durability tests of the Co1Sr0.3 catalysts showed strong water vapor resistance and stability, as well as excellent low-temperature activity and resistance to sintering in the oxidation reactions of other typical hydrocarbons such as toluene and propylene. This study provides a general strategy for achieving thermal catalysts by perfectly combining both highly low-temperature activity and sintering resistance, which will have great significance in practical applications for replacing precious materials with comparative features.

Removing Heavy Metals: Cutting-Edge Strategies and Advancements in Biosorption Technology.

This article explores recent advancements and innovative strategies in biosorption technology, with a particular focus on the removal of heavy metals, such as Cu(II), Pb(II), Cr(III), Cr(VI), Zn(II), and Ni(II), and a metalloid, As(V), from various sources. Detailed information on biosorbents, including their composition, structure, and performance metrics in heavy metal sorption, is presented. Specific attention is given to the numerical values of the adsorption capacities for each metal, showcasing the efficacy of biosorbents in removing Cu (up to 96.4%), Pb (up to 95%), Cr (up to 99.9%), Zn (up to 99%), Ni (up to 93.8%), and As (up to 92.9%) from wastewater and industrial effluents. In addition, the issue of biosorbent deactivation and failure over time is highlighted as it is crucial for the successful implementation of adsorption in practical applications. Such phenomena as blockage by other cations or chemical decomposition are reported, and chemical, thermal, and microwave treatments are indicated as effective regeneration techniques. Ongoing research should focus on the development of more resilient biosorbent materials, optimizing regeneration techniques, and exploring innovative approaches to improve the long-term performance and sustainability of biosorption technologies. The analysis showed that biosorption emerges as a promising strategy for alleviating pollutants in wastewater and industrial effluents, offering a sustainable and environmentally friendly approach to addressing water pollution challenges.

Formulation of Catalytic Deep Eutectic Solvent for H2S Oxidative Absorption at Ambient Condition with Assistance of Cosmo-Rs

H2S is very well known for its toxicity, corrosivity, flammability and explosiveness which in overall lead to operational difficulty. Hence, raising the need for H2S sweetening process. However, the current conventional sweetening process is very energy intensive besides suffer from catalyst deactivation issue. Therefore, raising the need for more environmentally and economical friendly approach such as utilizing green solvent like deep eutectic solvent. Thus, the objective of this research is to determine the best combination of HBD and HBA components for catalytic DESs to convert H2S at room temperature. The study utilized COSMO-RS computational to assist in selecting the appropriate components, synthesized and characterized the chosen catalytic DES, and performed oxidative absorption of H2S using the selected DES. Initially, the solubility and selectivity performance of various HBD and HBA were evaluated, and the components with the best performance were combined with CuCl2.2H2O to form catalytic DES. The synthesized catalytic DES was characterized using FTIR and tested for its oxidation absorption capability. Based on the COSMO-RS screening, 1-butyl-3-methylimidazoilum chloride [bmim][Cl] and ethylene glycol [EG] were determined to be the best HBD and HBA, respectively. The catalytic DES formed from these components was homogeneous and brown in colour. The results of oxidative absorption showed that the catalytic DES rapidly produced a yellow precipitate, which was later confirmed to be sulphur. The study concludes that COSMO-RS computational can be used to formulate DESs for H2S oxidative absorption, and catalytic DES maintained its properties before and after H2S oxidation. The research also suggests that oxidative absorption of H2S to sulphur using catalytic DESs is a feasible and rapid.

Design and Preparation of a Bifunctional Nanobiohybrid Catalyst by Combining Palladium and α‐Amylase Enzyme: Application in One‐pot Chemoenzymatic Catalysis

AbstractA chemoenzymatic approach that combines chemical and bio‐catalyst has proven very useful in synthetic chemistry, however, mutual deactivation of chemical and bio‐catalyst when employed in the same pot is still a challenge. In this context, the development of nanobiohybrid catalysts has played an important role and overcoming the issue of mutual deactivation between catalysts to a certain extent. Herein, we design and synthesize a novel heterogeneous recyclable nanobiohybrid catalyst comprising palladium nanoparticles and α‐amylase from Aspergillus oryzae immobilized onto halloysite nanotubes as a solid heterogeneous support. Further, the wider applicability of the developed nanobiohybrid catalyst is revealed in the one‐pot chemoenzymatic synthesis of functionalized biphenyls and bis(indolyl)methanes which consists of Pd‐catalyzed Suzuki‐Miyaura coupling and α‐amylase mediated aza‐Michael addition or electrophilic substitution reactions respectively. Further, the robustness and generality of the developed one‐pot chemoenzymatic synthesis are demonstrated by incorporating different substitutions at the starting materials and obtaining the corresponding products in moderate to good yields.

Rapid synthesis of Cu-SSZ-39 and study of phosphorus poisoning in NH3-SCR

Cu-SSZ-39 has attracted great interest due to its excellent NH3-SCR activity and hydrothermal stability. However, impediments such as high synthesis costs, lengthy preparation duration, and the issue of phosphorus-induced deactivation have hampered its widespread commercialization. Herein, H2O2 was first introduced into the synthesis system dedicated to the rapid synthesis of SSZ-39, and the crystallization time was shortened to 3 d. Various characterization techniques were used to analyze deeply the structure–activity relationship of the resulting Cu-SSZ-39 catalysts before and after phosphorus poisoning. Our findings revealed a pronounced decline in acidic sites and active copper species as Cu-SSZ-39 underwent deeper phosphorus poisoning, leading to the formation of Cu-P species and a consequential reduction in the low-temperature activity of the catalyst. Surprisingly, hydrothermal treatment of the poisoned catalyst allowed the decomposition of Cu-P species to generate active Cu2+ species, alleviating the poisoning effect. It was also shown that phosphorus poisoning did not affect the low-temperature reaction mechanism of Cu-SSZ-39, which still followed the “L-H” reaction pathway. Finally, it was unexpectedly found that the anti-phosphorus poisoning performance of 0.9C-Cu-SSZ-39 significantly improved after mesopores were introduced.

Enabling pure CO2 reduction on Ni{Cu}x-YSZ electrode via an oxide-mediated mechanism

Ni-YSZ-based electrodes are well-known as CO2 reduction cathodes. These electrodes require the presence of safe gases such as H2 or CO in the CO2 inlet stream, adding substantial complexity to the devices. Various reasons such as electrode oxidation and coking have been historically attributed to electrode failure in pure CO2 streams. Using operando Raman spectroscopy and online mass spectroscopy, we have shown that Ni-YSZ electrodes can, in fact, be operated within certain limits. Our measurements reveal that under operation conditions, Ni-YSZ, in fact, oxidizes to NiOx-YSZ. However, it is this oxide that enables the CO2 reduction via a surface oxygen and oxygen vacancy-mediated mechanism. The deactivation of the electrode coincides with strongly reducing conditions where the NiOx is reduced to metallic Ni. Cu-infiltration into Ni-YSZ architecture was demonstrated to mitigate the deactivation issue by modulating the Ni-O-Ni bond strengths and forming a more stable oxide on Ni. This oxide with higher stability to reduction continued to carry out CO2 reduction under strongly reducing conditions. The new electrode also demonstrated improved kinetics and stability against carbon deposition via Boudouard reaction.

Structural Heredity in Catalysis: CO2 Self-Selective CeO2 Nanocrystals for Efficient Photothermal CO2 Hydrogenation to Methane.

The chemical inertness of CO2 molecules makes their adsorption and activation on a catalyst surface one of the key challenges in recycling CO2 into chemical fuels. However, the traditional template synthesis and chemical modification strategies used to tackle this problem face severe structural collapse and modifier deactivation issues during the often-needed post-processing procedure. Herein, a CO2 self-selective hydrothermal growth strategy is proposed for the synthesis of CeO2 octahedral nanocrystals that participate in strong physicochemical interactions with CO2 molecules. The intense affinity for CO2 molecules persists during successive high-temperature treatments required for Ni deposition. This demonstrates the excellent structural heredity of the CO2 self-selective CeO2 nanocrystals, which leads to an outstanding photothermal CH4 productivity exceeding 9mmol h-1 mcat -2 and an impressive selectivity of >99%. The excellent performance is correlated with the abundant oxygen vacancies and hydroxyl species on the CeO2 surface, which create many frustrated Lewis-pair active sites, and the strong interaction between Ni and CeO2 that promotes the dissociation of H2 molecules and the spillover of H atoms, thereby greatly benefitting the photothermal CO2 methanation reaction. This self-selective hydrothermal growth strategy represents a new pathway for the development of effective catalysts for targeted chemical reactions.

Nanoparticle Exsolution on Perovskite Oxides: Insights into Mechanism, Characteristics and Novel Strategies.

Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications, including fuel cells, chemical conversion, and batteries. Nanocatalysts demonstrate high activity by expanding the number of active sites, but they also intensify deactivation issues, such as agglomeration and poisoning, simultaneously. Exsolution for bottom-up synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional nanomaterials. Nanoparticles are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction process. Their uniformity and stability, resulting from the socketed structure, play a crucial role in the development of novel nanocatalysts. Recently, tremendous research efforts have been dedicated to further controlling exsolution particles. To effectively address exsolution at a more precise level, understanding the underlying mechanism is essential. This review presents a comprehensive overview of the exsolution mechanism, with a focus on its driving force, processes, properties, and synergetic strategies, as well as new pathways for optimizing nanocatalysts in diverse applications.

Engineered nanoconfinement activates Fenton catalyst at neutral pH: Mechanism and kinetics study

We proposed to establish nanoscale spatially confined Fenton treatment architectures to overcome the catalyst deactivation issue frequently seen at neutral pH. We demonstrated this idea by growing four typical iron oxide catalysts (Fe3O4, FeOOH, CuFe2O4, and FeOCl), respectively inside the nanochannels of anodized aluminum oxide scaffold, wherein the confined space (≈5 nm) significantly accelerated heterogeneous Fenton treatment of organic pollutants, with up to 310 times kinetics enhancement under normalized surface area compared to the counterpart bulk reactions with suspension catalysts. Based on experimental and computational studies, we gained the mechanistic details on how did the nanoconfinement enhanced the protonation of surfaces driving the catalysis, and showed how much of its significance over other influencing factors on enhancing the treatment kinetics and a sustained catalysis. Our findings mark an important advance on developing nanoconfined Fenton treatment systems that enable efficient catalyst activation and maximal treatment kinetics, without additional chemicals or electro-/photo-energies.

Load rebound suppression strategy and demand response potential of thermal storage HVAC systems: An experimental and simulation study

The problem of power imbalance caused by the large power consumption of heating, ventilation and air-conditioning (HVAC) units in the summertime can be alleviated by building demand response (DR) strategies. However, after DR, load rebound will occur due to the sudden increase in demand. Meanwhile, there is a general lack of information on effective DR strategies. To study the DR potential and load rebound suppression strategies of HVAC systems, nine operation strategies were devised and applied experimentally. The physical experiments were conducted on a central air-conditioning system to investigate control strategies such as regional temperature reset, active energy storage, cold source unit activation and deactivation, as well as pre-cooling. Additionally, a simulation model was developed utilizing TRNSYS. DR evaluation indices, such as duration, power reduction capability, system operation cost, etc. were applied. The experimental results show that after a water storage tank is added as a buffer tank, the start and stop times of the air source heat pump were reduced from 46 to 6. Utilizing the thermal inertia of building and HVAC system, while ensuring personnel's thermal comfort, the DR participation time can be extended to 40–50 min. This will result in an 8.9 %–12.6 % reduction in power consumption. The simulation results show that with active energy storage added, HVAC system's DR participation time can be increased to about 120 min, the maximum power consumption can be reduced by 23.4 %, and the maximum operating cost can be reduced by 21.7 %. The study shows that a slow recovery strategy and the extension of DR control time can limit load rebound effectively. From the result of load rebound suppression effect, if the load rebound suppression strategy is not adopted, the power after DR will be 3.7 % higher than that pre-DR; the load rebound suppression strategy is adopted, which is 3.6 % lower than that pre-DR. By implementing the proposed DR strategies, the issue of frequent activation and deactivation of refrigeration units can be effectively mitigated. This will greatly alleviate the power supply and demand contradiction, while also effectively suppressing the load rebound effect to prevent a secondary peak in power consumption.

A review of prospects and challenges of photocatalytic decomposition of volatile organic compounds (VOCs) under humid environment

AbstractVolatile organic compounds (VOCs) are harmful for humans and the surrounding ecosystem. Emissions from these pollutants have caused a significant reduction in air quality, which has an effect on people's health. Alkanes, alkenes, alcohols, aromatics, and other VOC pollutants have all been broken down by TiO2 photocatalytic processes. Due to several operating inefficiencies and deactivation issues in humid environments, the practical application of photocatalysis has not been realized on a broader scale. The effectiveness of photo‐oxidation of VOCs is impacted by a variety of environmental conditions. In the photocatalytic oxidation of the VOCs, relative humidity (RH) is critical. Therefore, it is important to review the recent findings on how humidity affects the photocatalytic breakdown of VOCs in air. To satisfy this need, this work provides a critical review of the related literature with focus on the fundamentals of photocatalysis, photocatalytic degradation of air pollutants, and the influence of humidity on the photocatalytic process degradation for selected air pollutants. It also highlights the kinetic models and typical photocatalytic reactor and supports for VOC removal.

Study on Stable Lithiophilic Ag Modification Layer on Copper Current Collector for High Coulombic-Efficiency Lithium Metal Anode

High energy-density lithium metal batteries will be crucial in improving the driving range and promoting electric vehicles. The lithophilic modification layer is usually introduced to improve CE and cycle stability. However, the stability of the lithophilic modified layer in long-term cycling and lithophilic modification strategies for anode current collectors in all-solid-state anode-free lithium batteries are rarely investigated. Here, we prove the failure process of the silver lithophilic modified layer towards lithium metal anode through electrochemical cycling in liquid electrolytes. Combined with EIS, SEM, and XPS analysis, the failure is due to the formation of SEI on the Ag surface and the silver particles’ peeling off from the current collector during cycling, which forms “dead silver.” And we construct carbon-incorporated lithium phosphorous oxynitride (LiCPON) -based all-solid-state Li/Cu half-cells to evaluate the stability of the lithophilic Ag layer. The introduction of Ag between solid electrolyte (LiCPON) and current collector enables the long-term cycle (367th) of all-solid-state Li/Cu half cells with high CE. Our work clarifies the issue of Ag deactivation and provides a method for evaluating modified layers’ use and building stable electrolyte/anode interfaces in all-solid-state anode-free lithium batteries.

Dual single-atom catalyst design to build robust oxygen reduction electrode via free radical scavenging

Metal-nitrogen-carbon materials are the most promising platinum replacement catalysts for oxygen reduction reaction. However, lacking an efficient approach to improve durability—i.e., to cope with the attack by in situ formed radicals, leaching of central ions, etc.—has limited these catalysts from widespread application. Herein we present a novel, dual-metal, single-atom catalyst design (Fe,Ce-N-C) to confront the formidable deactivation issue of the best-performing yet unstable Fe-N-C catalysts. Cerium single sites are revealed as efficient chemical catalysts to catalyze the H2O2 disproportionation into O2, leading to increased 4e selectivity. Moreover, rather than Fe single sites that catalyze the formation of reactive ·OH and ·OOH species, these cerium single sites act proactively to eliminate in situ-generated radicals. The final Fe,Ce-N-C catalyst represents excellent durability exceeding that of Fe-N-C. This work opens a new path to alleviate the degradation of Fe-N-C catalysts in an acidic medium.

Nickel-based cerium zirconate inorganic complex structures for CO2 valorisation via dry reforming of methane

The increasing anthropogenic emissions of greenhouse gases (GHG) is encouraging extensive research in CO2 utilisation. Dry reforming of methane (DRM) depicts a viable strategy to convert both CO2 and CH4 into syngas, a worthwhile chemical intermediate. Among the different active phases for DRM, the use of nickel as catalyst is economically favourable, but typically deactivates due to sintering and carbon deposition. The stabilisation of Ni at different loadings in cerium zirconate inorganic complex structures is investigated in this work as strategy to develop robust Ni-based DRM catalysts. XRD and TPR-H2 analyses confirmed the existence of different phases according to the Ni loading in these materials. Besides, superficial Ni is observed as well as the existence of a CeNiO3 perovskite structure. The catalytic activity was tested, proving that 10 wt.% Ni loading is the optimum which maximises conversion. This catalyst was also tested in long-term stability experiments at 600 and 800°C in order to study the potential deactivation issues at two different temperatures. At 600°C, carbon formation is the main cause of catalytic deactivation, whereas a robust stability is shown at 800°C, observing no sintering of the active phase evidencing the success of this strategy rendering a new family of economically appealing CO2 and biogas mixtures upgrading catalysts.