Temperature-programmed Reaction Research Articles

Impact of mild hydrothermal aging on kinetics of NH[formula omitted], NO, SO[formula omitted] and CO oxidation reactions on Cu/SSZ-13 catalyst

Cu/SSZ-13 is a catalyst commonly used for selective catalytic reduction (SCR) of nitrogen oxides (NOx) in diesel engine exhaust. Standard configurations are based on SCR preceded by an oxidation catalyst, however, a close-coupled SCR configuration appears relevant for upcoming regulations addressing cold-start emissions. Two often discussed ion-exchanged Cu sites in Cu/SSZ-13 are denoted ZCuOH and Z2Cu, where Z represents an Al atom in the zeolite framework. Mild hydrothermal aging (HTA) causes Cu redistribution within the catalyst; ZCuOH sites transform into more stable Z2Cu species. In this work, the effect of mild HTA on NH3, NO, SO2, and CO oxidation is studied on a commercial Cu/SSZ-13 sample. Temperature-programmed reaction experiments, performed in a lab reactor, and previously published catalyst characterization data using H2-TPR, NH3-TPD, and DRIFTS were used to build and validate a mathematical model. It couples the kinetics of the oxidation reactions with ZCuOH and Z2Cu concentration evolution during mild HTA. The model uses two distinct rate coefficients for ZCuOH and Z2Cu sites, allowing prediction of the catalyst activity during aging. The results suggest that the rate coefficients for the studied reactions on Z2Cu are effectively nil, so the observed activity in NH3, NO, SO2, and CO oxidation can be attributed solely to ZCuOH sites.

Ru/MgO catalyst with dual Ru structure sites for efficient CO production from CO2 hydrogenation

The development and comprehension of supported metal catalysts for CO2 hydrogenation is of paramount importance in mitigating the net CO2 emissions. Supported Ru catalysts have been widely recognized in facilitating CO2 methanation, on which recent findings suggest that the CO2 hydrogenation process can be manipulated to favor the reverse water–gas shift (RWGS) pathway by precisely adjusting the size of Ru particles. However, the size-dependent impact of Ru remains a topic of lively debate. In this work, Ru/MgO catalysts with Ru in the form of single atoms (Ru1) and few-atom cluster (RuFAC) structures were prepared for CO2 hydrogenation. The 1.0Ru/MgO catalyst (with 1 wt.% of Ru), featuring a mixture of Ru1 and RuFAC with a size of 0.6–1.0 nm, showed the highest CO yield (38% at 500 °C) with balanced CO2 conversion and CO selectivity. Transient CO2 hydrogenation and temperature-programmed surface reaction (TPSR) studies suggested that the adsorbed CO2 species participated in CO2 hydrogenation. On Ru1 sites, CO2 hydrogenation followed the RWGS pathway, resulting in the production of CO. In contrast, on RuFAC sites, the enhanced H2 dissociation ability, along with the presence of adsorbed bidentate and monodentate carbonate species at the Ru−MgO interfaces, facilitated the formation of CH4 through the CO2 methanation pathway. This study highlights the critical roles of Ru structure and local environment in defining the CO2 hydrogenation pathways and provides new design principles for highly active Ru-based catalysts.

Interpretation of H2-TPR from Cu-CHA Using First-Principles Calculations.

Temperature-programmed reduction and oxidation are used to obtain information on the presence and abundance of different species in complex catalytic materials. The interpretation of the temperature-programmed reaction profiles is, however, often challenging. One example is H2 temperature-programmed reduction (H2-TPR) of Cu-chabazite (Cu-CHA), which is a material used for ammonia assisted selective catalytic reduction of NOx (NH3-SCR). The TPR profiles of Cu-CHA consist generally of three main peaks. A peak at 220 °C is commonly assigned to ZCuOH, whereas peaks at 360 and 500 °C generally are assigned to Z2Cu, where Z represents an Al site. Here, we analyze H2-TPR over Cu-CHA by density functional theory calculations, microkinetic modeling, and TPR measurements of samples pretreated to have a dominant Cu species. We find that H2 can react with Cu ions in oxidation state +2, whereas adsorption on Cu ions in +1 is endothermic. Kinetic modeling of the TPR profiles suggests that the 220 °C peak can be assigned to Z2CuOCu and ZCuOH, whereas the peaks at higher temperatures can be assigned to paired Z2Cu and Z2CuHOOHCu species (360 °C) or paired Z2Cu and Z2CuOOCu (500 °C). The results are in good agreement with the experiments and facilitate the interpretation of future TPR experiments.

Boosting N2O Catalytic Decomposition by the Synergistic Effect of Multiple Elements in Cobalt-Based High-Entropy Oxides.

Nitrous oxide (N2O) has a detrimental impact on the greenhouse effect, and its efficient catalytic decomposition at low temperatures remains challenging. Herein, the cobalt-based high-entropy oxide with a spinel-type structure (Co-HEO) is successfully fabricated via a facile coprecipitation method for N2O catalytic decomposition. The obtained Co-HEO catalyst displays more remarkable catalytic performance and higher thermal stability compared with single and binary Co-based oxides, as the temperature of 90% N2O decomposition (T90) is 356 °C. A series of characterization results reveal that the synergistic effect of multiple elements enhances the reducibility and augments oxygen vacancy in the high-entropy system, thus boosting the activity of the Co-HEO catalyst. Moreover, density functional theory (DFT) calculations and the temperature-programmed surface reaction (TPSR) with isotope labeling demonstrate that N2O decomposition on the Co-HEO catalyst follows the Langmuir-Hinshelwood (L-H) mechanism with the promotion of abundant oxygen vacancies. This work provides a fundamental understanding of the synergistic catalytic effect in N2O decomposition and paves the way for the novel environmental catalytic applications of HEO.

Same size, same support, same spectator? Selective acetylene hydrogenation on supported Pd nanoparticles.

The selective hydrogenation of acetylene catalyzed by Pd nanoparticles is industrially used to increase the purity of ethylene. Despite the implementation of Pd based catalysts on an industrial scale, little is known about metal-support interactions on a fundamental level due to the complexity of these systems. In this study, the influence of metal-support interactions between Pd nanoparticles and two electronically modified a-SiO2 thin films on acetylene hydrogenation is investigated under ultra-high vacuum (UHV) conditions. The hydrogenation is performed under isothermal reaction conditions using a pulsed molecular beam reactive scattering (pMBRS) technique. Besides the activity and selectivity of clean Pd particles also the impact of dehydrogenated species intentionally introduced a priori is elucidated, whereas the active phase of the catalyst is additionally characterized by CO infrared reflection-absorption spectroscopy (IRRAS) and post-mortem temperature-programmed reaction (TPR). Metal-support interactions are found to influence the catalytic properties of Pd particles by charge-transfer, where positive charging leads to increased activity for acetylene hydrogenation. However, the increased activity is accompanied by formation of undesired byproducts. The active sites for acetylene and ethylene hydrogenation are shown to be different as previously proposed by the A and E model. The availability of the two different active sites on the Pd nanoparticles is determined by dehydrogenated species, whose nature and stability can be tuned by metal-support interactions. Based on these findings an electronic model is proposed how selectivity for acetylene hydrogenation can be steered solely by metal-support interactions leading to blocking of unselective sites in situ.

Insight into the enhanced catalytic performance of phosphate-modified ZrO2/SBA-15 for the conversion of biobased 2,5-dimethylfuran and ethylene into p-xylene

Catalytic conversion of biomass-derived platform chemicals into bulk chemicals p-xylene (PX) is appealing yet challenging due to low catalytic efficiency and severe reaction conditions. In this work, we fabricated a series of phosphate-modified ZrO2/SBA-15 (xP-Zr/SBA-15) via adjusting the addition of phosphoric acid, and used them for the catalytic conversion biomass-derived 2,5-dimethylfuran (DMF) and ethylene to PX. Because of the enhanced adsorption capability for the reactant molecules (DMF and ethylene) and the good synergistic effect between Brønsted acid sites (P-OH) and Lewis acid sites (Zr4+), 30P-Zr/SBA-15 revealed an excellent catalytic performance in the selective conversion of DMF into PX. The DMF conversion was 98.5%, PX yield was 92.0% at 250 °C for 12 h, and the corresponding PX productivity was upto 50.5 mmolPX·gcat−1·h−1. The results are far superior to those obtained on most previously reported catalysts in the literature under similar reaction conditions. The kinetic study revealed that 30P-Zr/SBA-15 has a lower apparent activation energy for the tandem reaction including the Diels-Alder reaction (57.0 kJ·mo−1) and dehydration reaction (37.7 kJ·mo−1). Moreover, the 30P-Zr/SBA-15 catalyst exhibited the excellent recyclability and could be recycled at least six times without a significant loss of activity. On the basis of the temperature-programmed surface reaction of DMF and ethylene, a reasonable reaction mechanism was proposed.

Ni-BaMnO3 Perovskite Catalysts for NOx-Assisted Soot Oxidation: Analyzing the Effect of the Nickel Addition Method

In this study, we analyzed the role of a series of BaMn1−xNixO3 (x = 0, 0.2, and 0.4) mixed oxide catalysts, synthesized using the sol–gel method, in NOx-assisted diesel soot oxidation. ICP-OES, XRD, XPS, and H2-TPR techniques were used for characterization and Temperature-Programmed Reaction experiments (NOx-TPR and Soot-NOx-TPR), and isothermal reactions at 450 °C (for the most active sample) were carried out to determine the catalytic activity. All samples catalyzed NO and soot oxidation at temperatures below 400 °C, presenting nickel-containing catalysts with the highest soot conversion and selectivity to CO2. However, the nickel content did not significantly modify the catalytic performance, and in order to improve it, two catalysts (5 wt % in Ni) were synthesized via the hydrothermal method (BMN2H) and the impregnation of nickel on a BaMnO3 perovskite as support (M5). The two samples presented higher activity for NO and soot oxidation than BMN2E (obtained via the sol–gel method) as they presented more nickel on the surface (as determined via XPS). BMN2H was more active than M5 as it presented (i) more surface oxygen vacancies, which are active sites for oxidation reactions; (ii) improved redox properties; and (iii) a lower average crystal size for nickel (as NiO). As a consequence of these properties, BMN2H featured a high soot oxidation rate at 450 °C, which hindered the accumulation of soot during the reaction and, thus, the deactivation of the catalyst.

How bimetallic CoMo carbides and nitrides improve CO oxidation

CO elimination is an important step for the proper management of gaseous effluents from various processes, thus avoiding adverse impacts on the environment and human health. In this study, different bimetallic Al2O3-supported CoMo catalysts have been developed, characterized, and tested in the CO oxidation reaction, based on their respective oxides, carbides, and nitrides phases. The parent CoMo-oxide catalyst (CoMo) was prepared by impregnation and then transformed to its carburized (CoMoC) and nitrided (CoMoN) forms using temperature-programmed reaction methods under controlled atmospheres of CH4/H2 and NH3, respectively. The catalytic results demonstrate that the CoMoC catalyst exhibits higher activity compared to its CoMoN counterpart, and both are more active than the parent CoMo catalyst. Furthermore, the reduction temperature and space velocity were key process factors, which notably influenced activity and kinetic parameters, while the increase of reduction time does not seem to improve catalytic behavior. These results were associated with a better metal dispersion, and relatively higher reduction grade and metallic surface area on the carbides and nitrides, opening the possibility that new adsorption sites may be created. The catalytic results compare favorably with other non-noble metal catalysts, such as Cr-, Cu-, Fe-, and Ni-based samples, and highlight the potential of using carbides and nitrides as alternative formulations to enhance the performance of CO oxidation.

Rb-Ni/Al2O3 as dual functional material for continuous CO2 capture and selective hydrogenation to CO

Ni-based dual-functional materials (DFMs) have been widely investigated for CO2 capture and reduction with H2 (CCR). However, controlling the selectivity of CO2 hydrogenation to CH4 or CO is a fundamental challenge. Most Ni-based DFMs favor the selectivity of CH4 over CO, although CO is more desirable than CH4 from a chemical-synthesis perspective. In this study, Rb-promoted Ni nanoparticles on Al2O3, Rb-Ni/Al2O3, are developed as an effective DFM for selective CO production through CCR with a CO2 conversion of 68% and a CO selectivity of 97% under isothermal conditions at 450 °C in the mixture of O2 during CO2 capture process. The developed Rb-Ni/Al2O3 is applicable to continuous CCR using double reactor system. The roles of Rb and Ni in CCR over Rb-Ni/Al2O3 for CO formation are also discussed based on temperature-programmed surface reactions and in situ spectroscopic studies.

Activation of dimethyl carbonate on CeO2 surface: A combined experimental and theoretical study

Dimethyl carbonate (DMC) has recently emerged as a green reagent that finds versatile applications in methoxycarbonylation, carbonylation, and methylation reactions due to its multiple functionalities. In order to optimize the activity/selectivity of DMC-mediated heterogeneous catalytic reaction, it is imperative to enhance the fundamental understanding of the activation of DMC on the catalyst surface. In this study, the chemistry of DMC on the CeO2(111) surface was investigated using in-situ infrared spectroscopy, temperature-programmed surface reaction, and density functional theory calculations. It is shown that DMC readily converts into adsorbed methoxycarbonyl and methoxy on CeO2(111) at near room temperature. Upon heating, methoxycarbonyl decomposes into methoxy and carbonyl; the formed carbonyl could react with the surface oxygen atom (OS) of CeO2(111) to form desorbed carbon dioxide (COOS), leaving a surface oxygen vacancy. The surface methoxy groups undergo intermolecular hydrogen transfer to form CH3OH and HCHO, which upon heating either desorb or dehydrogenate with OS to form adsorbed methoxy and formate (with OSH), respectively. Adsorbed formate could react with OS to form desorbed COOS at higher temperatures. These findings provide fundamental insights into the catalytic chemistry of DMC on CeO2(111) surface, which may prove informative for the CeO2-catalyzed DMC-mediated reactions.

Quantifying Carbon Active Sites Chemisorbing Hydrogen on Oxygen Containing Activated Carbons during Heat Treatment in Hydrogen Atmosphere.

Carbon edge sites have been widely studied because of their importance in surface reactivity and electronic properties. The surface chemistry of the carbon edge sites is relevant to various reactions, and carbon active sites are key topics in many applications. Temperature-programmed desorption (TPD) and temperature-programmed reaction (TPR) techniques are used to clarify the fate of oxygen atoms present as CO-yielding functional groups on the activated carbon during heat treatment in hydrogen with an argon balance atmosphere. It has been elucidated that CO is decomposed, H2O is released by a reduction reaction with atmospheric H2, and CO2 is evolved by secondary reactions from the CO-yielding functional groups during TPR. Atmospheric H2 consumption during TPR is observed and its rate is characterized. The amounts of carbon active sites are quantified by determining the amount of H2 chemisorbed onto the carbon surfaces. Finally, it is quantitatively determined that the active sites that chemisorb hydrogen are generated after the decomposition of CO and CO2 caused by secondary reactions between ca. 700 and 1100 K from the CO-yielding functional groups. The origin of these CO-yielding functional groups is generally attributed to phenol/ether groups. In addition to these oxygen-containing functional group decompositions, some free sites on the edge sites are activated for H2 chemisorption by heat treatment between ca. 700 and 1100 K.

Catalytic Activity of Methane Oxidation on Nickel-doped Lanthanum Strontium Titanate Perovskite from Three Synthesis Methods

BackgroundThree perovskites of nickel-doped lanthanum strontium titanate (LSTN) were made and compared for their activity toward methane oxidation. MethodThe perovskite was synthesized separately via solid-state reaction, citrate complexation, and microwave-assisted methods. Significant FindingsThe perovskite from solid state reaction gave the highest activity of syngas production in repetitive redox cycles without any deterioration, demonstrating a great potential for use in chemical looping technology. Nevertheless, the material required activation in methane, as evidenced in studies of temperature-programmed surface reaction. On the contrary, the perovskite from the complexation method behaved completely different while the microwave-synthesized one gives the poorest activity. The variation of the activity was correlated with the distinct structure from different synthesis routes, which influences where a metal phase resides and how the metal anchors onto host oxides. The information obtained here would be of great benefit in making good material with desirable properties for catalysis and potential applications.

Mechanistic Insights into the Induction Period of Methanol-to-Olefin Conversion over ZSM-5 Catalysts: A Combined Temperature-Programmed Surface Reaction and Microkinetic Modeling Study

Mechanistic Insights into the Induction Period of Methanol-to-Olefin Conversion over ZSM-5 Catalysts: A Combined Temperature-Programmed Surface Reaction and Microkinetic Modeling Study

Advanced in situ IR spectroscopy study of anisole hydrodeoxygenation over Ni/SiO2 catalysts

Hydrodeoxygenation (HDO) of anisole was investigated over Ni/SiO2 catalysts prepared by incipient wetness impregnation (IWI) and deposition–precipitation (DP). The in situ FTIR, temperature-programmed surface reaction (TPSR-MS), as well as high pressure flow reactions were carried out to relate catalyst properties and reaction mechanism. The small-size Ni0-Ni+ species (2.0 nm) in Ni/SiO2-DP catalyst exhibits a strong hydrogenolysis activity for anisole, favouring the formation of phenol and benzene. The demethylation of anisole to phenol is a rapid step compared to the deoxygenation of phenol to benzene as indicated by in situ FTIR studies. The intensity of C–C stretching vibration in the two rings was enhanced with increasing temperature, suggesting the formation of condensed-ring products was promoted by high reaction temperature. The Ni/SiO2-IWI catalyst, which exhibits a larger Ni0 particle size (14.1 nm) and higher amount of desorbed H2 per surface Ni compared to Ni/SiO2-DP, shows a high hydrogenation but low hydrogenolysis activity, towards the formation of methoxycyclohexane under 40 bar H2 pressure flow reaction.

Ni-CeO2 nanocomposite with enhanced metal-support interaction for effective ammonia decomposition to hydrogen

Ammonia is a promising hydrogen storage material due to its ease of storage and decomposition to COx-free hydrogen. Herein, we report colloidal solution combustion synthesis (CSCS) to construct Ni-CeO2 nanocomposite catalysts for efficient ammonia decomposition to generate hydrogen. Unlike conventional supported Ni/CeO2 catalyst, the prepared Ni-CeO2 nanocomposite catalyst exhibited nickel embedded in CeO2 matrix with enhanced metal-support interaction. The physicochemical properties and metal-support interaction of the catalysts can be tuned by adjusting the amount of silica sol template. The resulted Ni-CeO2 nanocomposite catalysts exhibited outstanding catalytic performance in terms of activity and stability. The hydrogen production rate reached 32.9 mmol gcat−1 min−1 at 500 °C, which is superior to other state-of-the-art Ni-based catalysts and even comparable or better than some reported Ru-based catalysts. The systematic characterizations demonstrated that the unique Ni-CeO2 nanocomposite structure with enhanced metal-support interaction, not only provided a rich Ni-CeO2 interface to stabilize small-sized Ni nanoparticles, but also had a high concentration of oxygen vacancy to strengthen electronic metal-support interaction, making nickel surface electron-rich. The integrated studies of kinetics, temperature-programmed surface reaction, and DFT calculations corroborated that this enhanced metal-support interaction including geometric and electronic effects, favored the enrichment of NH3 on the catalyst surface and facilitated rate-determining N≡N bond formation step, thereby boosting the reaction rate. This study highlights the importance of designing new structural catalysts with enhanced metal-support interaction for boosting hydrogen production from ammonia decomposition.

Co3O4 decoration on iron-contained biochar composite fabricated by co-pyrolysis of red mud and spent coffee ground: A synergistic hybrid for Rhodamine B degradation via peroxymonosulfate activation

In this study, a composite was prepared by co-pyrolysis of red mud (RM) and spent coffee grounds (SCG). Then, cobalt was incorporated in the as-prepared RM/biochar composite (RMBC) and employed as the heterogeneous activator of peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. A temperature-programmed reaction and X-ray diffraction (XRD) measurements disclosed that the hematite (Fe2O3) phase in RM experienced a step-wise reduction to magnetite (Fe3O4) and Fe0 with increasing temperature during the co-pyrolysis of RM and SCG. The RMBC exhibited low performance for PMS activation to degrade RhB. However, incorporating 1.5 wt% Co can drastically improve the catalytic performance. The influence of initial pH, catalyst dosage, initial RhB concentrations, and temperature on the degradation efficiency was investigated. The quenching experiments combined with electron paramagnetic resonance analysis proved that the ·OH and SO•−4radicals, and 1O2 no-radical were the main reactive species for RhB degradation in the Co3O4/RMBC/PMS system.

Preparation of Mo2C by the temperature-programmed reaction between h-MoO3 and CO

In the work, the temperature-programmed reaction (TPR) between hexagonal-shaped h-MoO3 and high-purity CO under different heating rates was investigated in order to prepare Mo2C. Various technologies such as TG-DTA-DTG, XRD, FESEM, FT-IR and Raman spectrum as well as the thermodynamic calculation were adopted to analyze the experimental data. The results showed that the physically adsorbed water on the sample surface, the residual ammonium and coordinated water in the internal structure of h-MoO3 were successively released as the temperature increased, and then α-MoO3 and Mo4O11 were formed when the temperature arrived at around 791 K. Upon further increasing the temperature, the reduction process occurred and MoO2 will be generated. Thereafter, the carburization reaction was taken place and the subsequent reaction pathways were significantly different at lower and higher heating rates: at lower heating rates (8 and 12 K/min), the carburization process of MoO2 to Mo2C followed MoO2→MoO2+Mo2C→Mo2C + Mo→Mo2C; while at higher heating rates (16 and 20 K/min), the reaction pathways followed MoO2→MoO2+Mo2C→MoO2+Mo2C + Mo + MoOxCy→Mo→Mo2C, single-phase metallic Mo can be generated. The work also discovered that the as-prepared Mo2C always kept the same platelet-shaped morphology as that of the newly-formed MoO2; while due to the removal of oxygen and the decrease of molar volume during the transformation process, the as-prepared Mo2C exhibited a rougher and more porous morphological structure.

The Role of Fe in Ni-Fe/TiO2 Catalysts for the Dry Reforming of Methane

A series of nickel- and iron-modified titanium dioxide (Ni-Fe/TiO2) are studied for the dry reforming of methane (DRM) at 550 °C. Temperature-programmed surface reactions using CH4 and CO2 as probe molecules, as well as activity results, confirmed that both CO2 and CH4 conversion decreased with the addition of Fe. The XPS results obtained from reduced and used catalysts suggested changes in the surface nickel and iron species. Characterizations, particularly thermogravimetric analysis (TGA) and Raman spectroscopy over used catalysts, revealed that the addition of Fe can greatly inhibit the coke formation. In situ DRIFTS further identified that the addition of Fe favored the formation of carbonate species, which can facilitate the removal of coke deposited on the surface.

CO2/CO methanation over Ru and Ni supported γ-Al2O3: A study on the effect of the stoichiometry of reactant gases

CO2 and CO conversion to methane serves as a dual process as it helps in the depletion of CO and CO2 released in the atmosphere due to anthropogenic reasons and gives us by-products of high calorific value. Herein, we have studied the CO2 and CO methanation reaction at different stoichiometry using two supported catalysts: Ru/γ-Al2O3 and Ni/γ-Al2O3. The catalysts are prepared using hydrazine reduction, and the methanation reaction is tested using temperature-programmed reactions by varying the stoichiometric moles of hydrogen to study the effect on conversion and methane selectivity. Stoichiometry effect is important to study in cases where hydrogen is present in lesser quantities than the stoichiometry. In addition, the long-term stability is also studied for both catalysts for 40 hours and spent catalysts were characterized by the Thermogravimetric analysis (TGA), O2-Temperature programmed oxidation (O2-TPO) and X-ray photoelectron spectroscopy (XPS).

Crystal Plane Effect of Co3O4 on Styrene Catalytic Oxidation: Insights into the Role of Co3+ and Oxygen Mobility at Diverse Temperatures.

In the oxidation reaction of volatile organic compounds catalyzed by metal oxides, distinguishing the role of active metal sites and oxygen mobility at specific preferentially exposed crystal planes and diverse temperatures is challenging. Herein, Co3O4 catalysts with four different preferentially exposed crystal planes [(220), (222), (311), and (422)] and oxygen vacancy formation energies were synthesized and evaluated in styrene complete oxidation. It is demonstrated that the Co3O4 sheet (Co3O4-I) presents the highest C8H8 catalytic oxidation activity (R250°C = 8.26 μmol g-1 s-1 and WHSV = 120,000 mL h-1 g-1). Density functional theory studies reveal that it is difficult for the (311) and (222) crystal planes to form oxygen vacancies, but the (222) crystal plane is the most favorable for C8H8 adsorption regardless of the presence of oxygen vacancies. The combined analysis of temperature-programmed desorption and temperature-programmed surface reaction of C8H8 proves that Co3O4-I possesses the best C8H8 oxidation ability. It is proposed that specific surface area is vital at low temperature (below 250 °C) because it is related to the amount of surface-adsorbed oxygen species and low-temperature reducibility, while the ratio of surface Co3+/Co2+ plays a decisive role at higher temperature because of facile lattice oxygen mobility. In situ diffuse reflectance infrared Fourier spectroscopy and the 18O2 isotope experiment demonstrate that C8H8 oxidation over Co3O4-I, Co3O4-S, Co3O4-C, and Co3O4-F is mainly dominated by the Mars-van Krevelen mechanism. Furthermore, Co3O4-I shows superior thermal stability (57 h) and water resistance (1, 3, and 5 vol % H2O), which has the potential to be conducted in the actual industrial application.