Mars Van Krevelen Mechanism Research Articles

A simultaneous operando FTIR & Raman study of propane ODH mechanism over V-Zr-O catalysts

Simultaneous operando Raman and transmission FTIR spectroscopic measurements have been combined for the study of the structure-activity relationships of V-Zr-O catalysts during propane oxidative dehydrogenation (ODH). The combination of both spectroscopies during reaction allows the identification of reaction intermediates and yields structural information about the catalyst. The experimental results are compared with available data in the literature to propose a reaction mechanism for propane ODH on V-Zr-O catalytic systems, and to identify the role of different oxygen species bound to vanadium sites. The results are consistent with a Mars-van Krevelen mechanism. Besides, they clearly show higher activity of bridging oxygen sites (V-O-V, V-O-Zr) than terminal VO bonds.

Support and gas environment effects on the preferential oxidation of carbon monoxide over Co3O4 catalysts studied in situ

We have studied the effect of different supports (CeO2, ZrO2, SiC, SiO2 and Al2O3) on the catalytic performance and phase stability of Co3O4 nanoparticles during the preferential oxidation of CO (CO-PrOx) under different H2-rich gas environments and temperatures. Our results show that Co3O4/ZrO2 has superior CO oxidation activity, but transforms to Co0 and consequently forms CH4 at relatively low temperatures. The least reduced and least methanation active catalyst (Co3O4/Al2O3) also exhibits the lowest CO oxidation activity. Co-feeding H2O and CO2 suppresses CO oxidation over Co3O4/ZrO2 and Co3O4/SiC, but also suppresses Co0 and CH4 formation. In conclusion, weak nanoparticle-support interactions (as in Co3O4/ZrO2) favour high CO oxidation activity possibly via the Mars-van Krevelen mechanism. However, stronger interactions (as in Co3O4/Al2O3) help minimise Co0 and CH4 formation. Therefore, this work reveals the bi-functional role required of supports used in CO-PrOx, i.e., to enhance catalytic performance and improve the phase stability of Co3O4.

Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

The catalytic oxidation of biomass-derived 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising route to produce bioplastic monomers. Developing budget non-noble-metal catalysts for the efficient air-oxidation of HMF to FDCA is highly demanded but challenging. In this contribution, we present a facile and green vitamin C (VC)-assisted solid-state grinding method for synthesizing mesoporous Mn–Co spinel oxides with improved oxygen vacancy (Ov) concentration, which could offer a satisfactory FDCA yield of 96% using air as the oxygen source (130 °C, 1.5 MPa air, 3 h). Remarkably, Mn3Co2Ox–0.3VC offered an outstanding FDCA formation rate of 2611 μmolFDCA·gcat–1·h–1, which is the highest value achieved so far among ever-described Mn-based catalysts. Based on experimental studies, the catalytic performance of Mn–Co oxides for the oxidation of HMF corresponds well with their Mn–O bond intensities. The catalyst with a higher Ov concentration exhibits a weaker Mn–O bond intensity, which brings about a higher lattice oxygen (OL) reactivity. More importantly, density functional theory (DFT) calculations also demonstrate that increasing the Ov amount not only boosts the OL reactivity of the catalyst by reducing the formation energy of Ov but also contributes to the adsorption and activation of O2 over the catalyst by significantly cutting down the O2 adsorption energy, thus leading to an enhanced catalytic activity for the oxidation of HMF. Besides, the catalyst with a higher Ov concentration provides a stronger substrate adsorption ability, which may also promote the HMF oxidation reactions. This work provides insights into the role of Ov over Mn-based oxides in oxidation catalysis by a Mars–van Krevelen mechanism.

In Search of Factors Determining Activity of Co3O4 Nanoparticles Dispersed in Partially Exfoliated Montmorillonite Structure.

The paper discusses a formation of Mt–PAA composite containing a natural montmorillonite structure partially exfoliated by poly(acrylic acid) introduced through intercalation polymerization of acrylic acid. Mt–PAA was subsequently modified by controlled adsorption of Co2+ ions. The presence of aluminosilicate packets (clay) and carboxyl groups (hydrogel) led to the deposition of significant amounts of Co2+ ions, which after calcination formed the Co3O4 spinel particles. The conditions of the Co2+ ions’ deposition (pH, volume and concentration of Co(NO3)2 solution, as well as a type of pH-controlling agent) were widely varied. Physicochemical characterization of the prepared materials (including X-ray fluorescence (XRF), X-ray powder diffraction (XRD), low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (H2-TPR)) revealed that the modification conditions strongly influenced the content as well as the distribution of the Co3O4 active phase, tuning its reducibility. The latter parameter was, in turn, very important from the point of view of catalytic activity in the combustion of aromatic volatile organic compounds (VOCs) following the Mars–van Krevelen mechanism.

Origin of Water-Induced Deactivation of MnO2-Based Catalyst for Room-Temperature NO Oxidation: A First-Principles Microkinetic Study

MnO2-based catalysts exhibit remarkable activities in a room-temperature NO oxidation reaction (RT-NOR) but are challenged by water-induced deactivation. To improve the water-resistance driven by molecular-level mechanistic understanding, we herein report a systematic first-principles study and microkinetic simulation on elucidating the water-modulated RT-NOR mechanism on the notable β-MnO2 catalyst. Results show that RT-NOR preferentially follows the Mars-van Krevelen mechanism on β-MnO2(110) and that the coupling of lattice O (Olat) with NO sitting on the surface Mncus site is the rate-limiting step. The presence of H2O results in a competitive effect against NO adsorbing on Mncus and inhibits NO2 formation. More crucially, the H2O-dissociated H species eventually accumulate on Olat and are difficult to remove, which seriously poison the catalyst, although the Mncus-anchored OH intermediate can oxidize NO to NO2 via the nitrite/nitrate route. Weakening the H adsorption on Olat, as well as the H2O adsorption on Mncus, is thus proposed as conductive to alleviating MnO2 deactivation. More essentially, we find that the vacancy formation energy of Olat, Ef(Ovac), can serve as a unified descriptor for balancing H2O-resistance and catalytic activity; the excessively low Ef(Ovac) is the intrinsic origin of MnO2 susceptible to deactivation by H2O. By doping engineering guided by such a descriptor, we identify that the Cr-, Nb-, Ru-, or Rh-substituted doping can properly increase the Ef(Ovac) of MnO2 and weaken the H2O-induced deactivation in RT-NOR. These results may provide a theoretical basis on optimizing MnO2-based catalysts with improved H2O-resistance.

Co–CeO2 Interaction Induces the Mars–van Krevelen Mechanism in Dehydrogenation of Ethane

Introducing a catalyst for dehydrogenation of ethane (EDH) for steam cracking represents a promising solution with high feasibility to realize efficient ethylene production. We investigated EDH over transition-metal-doped CeO2 catalysts at 873 K in the presence of steam. Ce0.8Co0.2O2 exhibited high EDH activity and selectivity to ethylene (ca. 95%). In the absence of H2O, the catalytic activity dropped rapidly, indicating the promotive effect of H2O on ethylene formation. Catalytic experiments with water isotopes (D2O and H218O) demonstrated that EDH over Ce0.8Co0.2O2 proceeds through the Mars–van Krevelen (MvK) mechanism in which the reactive lattice oxygen in Ce0.8Co0.2O2 contributes to EDH. The consumed lattice oxygen was subsequently regenerated with H2O. X-ray diffraction and in situ X-ray absorption fine structure spectroscopy revealed that cobalt species were mainly present as CoO under EDH conditions and that redox between Co2+ and Co0 proceeded concomitantly with EDH. In contrast with Ce0.8Co0.2O2, no contribution of the lattice oxygen of CoO to EDH was verified in the case of CoO supported on α-Al2O3, which exhibited lower activity than Ce0.8Co0.2O2. Therefore, Co–CeO2 interactions are expected to play a crucially important role in controlling the characteristics of the reactive lattice oxygen suitable for EDH via the MvK mechanism.

An efficient strategy for selective oxidation of ammonia nitrogen into N2 over BiOCl photocatalyst

Selective oxidation of ammonia nitrogen (NH4+-N) into N2 is critical to remove the superfluous nitrogen in the hydrosphere and control the fixed nitrogen inventory for the global nitrogen cycle. Herein, on the basis of chlorine radical chemistry, we report the photocatalytic denitrogenation over BiOCl with high N2 selectivity (>97 %). Efficient Cl– conversion into reactive chlorine species (RCS) is achieved, serving as the predominant reactive species for NH4+-N oxidation. According to the zero-order kinetics of Cl– for RCS generation, as well as the Cl– extraction/insertion over BiOCl, a Cl–-mediated Mars-van Krevelen mechanism is revealed, by which the catalytic performance shifts from the undesired deactivation (because of photocorrosion) towards the remarkably enhanced reactivity. This system exhibits great potential for the denitrogenation of saline wastewater, also provides an interesting strategy to activate inert chemical bond via the chlorine cycle.

Insight into the Crystal Structures and Surface Property of Manganese Oxide on CO Catalytic Oxidation Performance.

α-MnO2 nanorods and flower-like γ-MnO2 microspheres were synthesized by facile and mild methods to illustrate the effect of crystal structures and surface features on catalytic performance with the help of carbon monoxide (CO) oxidation. It is revealed that the flower-like γ-MnO2 microspheres possess better catalytic oxidation performance (CO complete conversion temperature at 120 °C and long-time stability for 50 h) than α-MnO2 nanorods, which can be attributed to the obvious differences in the chemical bonds and linking modes of [MnO6] octahedra due to the different crystal structures. γ-MnO2 possesses lower Mn-O bond strength that enables γ-MnO2 to present a large amount of surface lattice oxygen and superior oxygen mobility. The disordered random intergrowth tunnel structure can adsorb effectively CO molecules, resulting in excellent catalytic performance for CO catalytic oxidation. In addition, the MnO2 catalyst probably occurred via a Mars-van Krevelen mechanism for CO oxidation. This work provides an insight into the effect of crystal structures and surface property of manganese oxide on catalytic oxidation performance, which presents help for the future design of promising catalysts with excellent catalytic performance.

Insight into the effect of manganese substitution on mesoporous hollow spinel cobalt oxides for catalytic oxidation of toluene

The cobalt oxides and manganese oxides have high-activity potential for catalytic oxidation of volatile organic compounds (VOCs), while the mesoporous hollow morphology is crucial to the mass transfer of reactant and product. Therefore, it is worth investigating the effect of manganese substitution in mesoporous hollow cobalt oxides on catalytic oxidation. Herein, a partially disordered spinel structure is formed by the Mn substitution in Co3O4 and the mesoporous hollow microsphere is improved in morphology homogeneity with the decrease of Co/Mn ratio in the range of 1.8–28.8. The 5Co1Mn (Mn-substituted Co3O4 with Co/Mn at 5.4) exhibits outstanding catalytic activity for toluene oxidation with 50% CO2 generation at 237 °C, which is 21 °C lower than Co3O4. Moreover, the 5Co1Mn displays satisfactory stability in reusability, lifetime, and water resistance. The small defective crystallite, mesoporous hollow morphology, and high specific surface area endow Mn-substituted Co3O4 with more surface chemical adsorbed oxygen, enhancing the catalytic oxidation of toluene. Theoretical calculation on (311) plane of Co3O4 reveals that Mn2+ or Mn3+ substitution increases the formation energy of oxygen vacancy and makes it difficult to adsorb gaseous oxygen on the defective surface. The interaction between Co and Mn impedes the improvement of toluene oxidation because the mobility of lattice oxygen, the surface distribution of Co3+, and the ratio of surface adsorbed oxygen to surface lattice oxygen are hindered by Mn substitution. The chemical adsorbed oxygen is more active than lattice oxygen in the oxidation of adsorbed intermediates (phenolate, benzoate species, etc.). The Langmuir-Hinshelwood mechanism dominates in the catalytic oxidation at 200–250 °C, while the catalytic oxidation follows both the Langmuir-Hinshelwood mechanism and Mars-van Krevelen mechanism above 250 °C. This work provides some enlightenment for exploring the role of surface oxygen species in VOCs oxidation and uncovering the interaction in binary spinel oxides.

X-ray photoelectron and Raman spectroscopy of nanostructured ceria in soot oxidation under operando conditions

Ceria nanoshapes exhibiting different amounts of {100}, {110} and {111} facets (cubes, rods, octahedra and polyhedra) were prepared, characterized, tested in the carbon soot oxidation reaction, and studied by operando near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and operando Raman spectroscopy up to 550 °C. The specific soot oxidation reaction rate (mgC·m−2·min−1) clearly indicated that the {110} and {100} crystallographic planes of ceria were more active than the {111} ones for the oxidation of carbon soot. As deduced from the Ce 3d and O 1s signals recorded using different photon energies, all ceria nanoshapes experienced progressive reduction upon increasing the temperature under Ar, which was accompanied by the formation of oxygen vacancies. Raman studies revealed that, at this stage, isolated graphene layers in carbon soot reacted with ceria lattice oxygen atoms following a Mars-Van Krevelen mechanism. After exposure to O2 at 550 °C, a broad signal in the O 1s region at 531.2–532.5 eV was ascribed to surface active oxygen species, such as peroxide (O22−) and superoxide (O2−) species, generated from the interaction of molecular O2 with oxygen vacancies, which proved to be highly reactive to oxidize the graphitic structures of carbon soot.

Integrated Reactor‐Combustor Recycling System for Safe Operation by Catalytic Removal of Excess O2

AbstractA reactor‐combustor recycling system is proposed for safe operation of a hydrocarbon‐ and O2‐rich reactor by catalytically combusting excess O2 and recycling generated CO2 for dilution. The Pt/Al2O3 catalysts are determined as active and stable, and the Mars van Krevelen mechanism is applied for the combustion kinetics. Modeling and simulation of the system involving reactor, heater, combustor, valve, and cooler are performed, where multitubular, monolith, and microstructured reactors are compared for addressing the strong exothermic combustion. The system is highly promising because 99.9 % O2 can be consumed and explosion risk be eliminated via CO2 dilution. The microstructured combustor exhibits the highest potential by considering heat management, pressure drop, and compactness.

Unravelling the role of Ag[sbnd]Cr interfacial synergistic effect in Ag/Cr2O3 nanostructured catalyst for the ammoxidation of toluene via low temperature activation of Csp3-H bond

An environmentally benign and cost-effective synthesis of benzonitrile is reported by direct oxidative cyanation of aromatic Csp3-H bonds of toluene over Ag(I)/Cr2O3 nanostructured catalyst. The catalyst was prepared by a hydrothermal route using cationic surfactant cetyltrimethylammonium bromide and was characterized by powder XRD, XPS, SEM, TEM, TGA, TPD, TPR, UV-visible, FTIR, XANES, and ICP-AES methods. Conjugal effect of Lewis plus Brønsted acidity coupled with AgCr interfacial synergistic interaction appears as detrimental for its high catalytic activity and selectivity (98.4%) for benzonitrile. In situ DRIFTS analysis suggested that the catalytic system proceeded via a reaction pathway explained by Mars-van Krevelen mechanism.

Utilizing the Oxygen Carrier Property of Cerium Iron Oxide for the Low-Temperature Synthesis of 1,3-butadiene from 1-butene

Low-temperature oxidative dehydrogenation (ODH) of 1-butene to 1,3-butadiene is one of the challenging reactions in the polymer industry. Towards this a highly dispersed cerium iron oxide was synthesized by citrate gel combustion method and employed for the synthesis of 1,3-butadiene (BD) from 1-butene. The reaction was carried out at low temperature under an oxygen-free atmosphere in a continuous flow mode fixed bed reactor. A decrease in the lattice parameters observed from PXRD and high-resolution TEM analysis proved that iron occupies cerium sites in the crystal lattice. XPS, TPR, and oxygen uptake studies quantified the nature and abundance of different oxygen species. ODH was observed through consuming lattice oxygens. The vacancies generated could be filled by re-oxidation with an external supply of oxygen which will restore the catalytic activity demonstrating the Mars van Krevelen mechanism.

Oxidation and Storage Mechanisms for Nitrogen Oxides on Variously Terminated (001) Surfaces of SrFeO3-δ and Sr3Fe2O7-δ Perovskites.

The Ruddlesden-Popper (RP)-type layered perovskite is a candidate material for a new nitrogen oxide (NOx) storage catalyst. Here, we investigate the adsorption and oxidation of NOx on the (001) surfaces of RP-type oxide Sr3Fe2O7-δ for all of the terminations by comparing to those of simple perovskite SrFeO3-δ by the density functional theory (DFT) calculations. The possible (001) cleavages of Sr3Fe2O7 generate two FeO2- and three SrO-terminated surfaces, and the calculated surface energies indicated that the SrO-terminated surface generated by the cleavage at the rock salt layer is the most stable one. The oxygen of the FeO2-terminated surfaces could be removed with significantly low energy because the process involves the favorable reduction of the Fe4+ site. Consequently, the surface oxygen at the FeO2 site could easily oxidize adsorbed NO to NO2 by the Mars-van Krevelen mechanism. The resulting oxygen vacancy in the surface would be filled easily with lattice oxygen in bulk. The oxidation of NO with adsorbed molecular O2 was unfavorable by both the Langmuir-Hinshelwood and Eley-Rideal mechanisms because this process does not involve the reduction of the Fe4+ site. The oxygen of the SrO-terminated surfaces was tightly bound and acted as the adsorption site of NO and NO2. An electron transfer strengthened the NOx binding to the surface by forming nitrite (NO2-) or nitrate (NO3-) species. The DFT calculations revealed that the RP-type structure promoted NOx oxidation and storage properties by forming active oxygen due to the Jahn-Teller distortion and by exposing SrO-terminated surfaces due to the cleavage at the rock salt layer.

Ternary multifunctional catalysts of polymeric carbon nitride coupled with Pt-embedded transition metal oxide to enhance light-driven photothermal catalytic degradation of VOCs

Light driven photothermal catalysis has been carried out by converting the light energy into heat to reach the light-off temperature of the reaction. Herein we have synthesized the ternary multifunctional catalysts of polymeric carbon nitride coupled with Pt-embedded transition metal oxide (Pt-Cox/CN), for the catalytic degradation of toluene. Under the condition of space velocity of 30,000 mL/(gh) and concentration of 210 ppm, toluene conversion and CO2 mineralization can reach 90% and 83% over Pt-Co20/CN, respectively. The introduction of an appropriate proportion of CoO enhances the light absorption of nanocomposites and improves the adsorption for toluene. Meanwhile, CoO promotes the proportion and mobility of adsorbed oxygen on the surface, which are conducive to the catalytic oxidation reaction according to the Mars-van Krevelen mechanism. The results also suggest that light irradiation serves as a source of heat to initiate photo-induced chemical reactions and promote photothermal catalytic oxidation by promoting the activation of lattice oxygen.

Impact of Mn addition on catalytic performance of Cu/SiBEA materials in total oxidation of aromatic volatile organic compounds

Dealuminated BEA zeolite (SiBEA) was chosen as a support of metal oxide(s) phase for catalytic combustion of volatile organic compounds (VOCs). Copper and/or manganese oxide(s) were deposited at various Cu/Mn molar ratios. Factors influencing the catalytic activity were found by chosen physicochemical methods, including XRD, XRF, low-temperature N2 adsorption, FT-IR, UV–Vis-DRS, STEM-EDX, XPS and H2-TPR. Depending on the chemical composition, CuO, (CuxMn3-x)1-δO4, Cu-doped Mn3O4 or Mn2O3 was formed as the dominant phase. The active phase particles were located mainly in the interparticle voids of the zeolite support. SiBEA gained Lewis acid sites after the introduction of the metal oxide phase, especially in the case of CuO deposition. The presence of copper in the catalytic system resulted in enhanced reducibility of the active phase, and in a consequence in high catalytic activity in the total oxidation of aromatic VOCs, which proceeds according to the Mars-van Krevelen mechanism. After the introduction of Mn, the co-existence of different valence forms was found due to the redox equilibrium: Cu2+ + Mn3+ = Cu+ + Mn4+. Definitely, the addition of Mn to Cu/SiBEA increased the number of available surface vacancies and had a beneficial effect on the catalytic performance.

Remove elemental mercury from simulated flue gas by flower-like MoS2 modified with nanoparticles MnO2

In this work, MoS2/MnO2 synthesized by hydrothermal methods was employed to remove Hg0 in flue gas. Benefited from the growth of MnO2 on the surface of MoS2, the specific surface area of the Mm adsorbent has increased. Compared with pure MoS2, specific surface area of Mm-30 has increased by 26.0287 m2/g. The MoS2 modified with 30 w.t. % MnO2 revealed higher mercury removal performance at 120 °C, which reached 93%. The oxidation of mercury over Mm-30 is proposed to follow Mars-van Krevelen mechanism, whereby the lattice oxygen in the adsorbent is consumed. In presence of NO, HCl, O2 and SO2, the effect of different concentrations on mercury oxidation is observed. Mm-30 adsorbent reveals stable mercury removal performance in the presence of NO and HCl, while it also exhibited good sulfur resistance under the condition of 400 ppm SO2 + N2. This phenomenon indicates that the adsorbent can be applied in power plants with medium concentrations of SO2, which facilitated the application of Mm-30 as a potential mercury removal adsorbent for power plants.

Synergetic effect dependence on activated oxygen in the interface of NiOx-modified Pt nanoparticles for the CO oxidation from first-principles.

CO oxidation on NiOx-modified Pt nanoparticles (NPs) was investigated by first-principles calculations and microkinetic methods. The binding energies of O2 and CO on NiOx/Pt suggest that CO adsorption is dominant and the CO oxidation mainly follows the Mars-van Krevelen (M-vK) mechanism. It was found that the interfacial O of NiOx/Pt played a key role in the combination of adsorbed CO to O, as well as the O2 dissociation. With a lower O vacancy formation energy, NiOx/Ptedge shows about four orders higher reaction rates than NiOx/Pt(100). Microkinetic analysis suggests that the rate-determining step also depends on the active O at the interface. The calculations highlight the synergetic effect difference of NiOx selectively deposited on the different sites of Pt NPs on the CO oxidation from the atomic reaction mechanism, and throws light on the high activity of CO oxidation on partially covered NiOx/Ptedge nanoparticles.

Factors determining surface oxygen vacancy formation energy in ternary spinel structure oxides with zinc.

Spinel oxides are an important class of materials for heterogeneous catalysis including photocatalysis and electrocatalysis. The surface O vacancy formation energy (EOvac) is a critical quantity for catalyst performance because the surface of metal oxide catalysts often acts as a reaction site, for example, in the Mars-van Krevelen mechanism. However, experimental evaluation of EOvac is very challenging. We obtained the EOvac for (100), (110), and (111) surfaces of normal zinc-based spinel oxides ZnAl2O4, ZnGa2O4, ZnIn2O4, ZnV2O4, ZnCr2O4, ZnMn2O4, ZnFe2O4, and ZnCo2O4. The most stable surface is (100) for all compounds. The smallest EOvac for a surface is the largest in the (100) surface except for ZnCo2O4. For (100) and (110) surfaces, there is a good correlation, over all spinels, between the smallest EOvac for the surface and bulk formation energy, while the ionization potential correlates well in (111) surfaces. Machine learning over EOvac of all surface sites in all orientations and for all compounds to find the important factors, or descriptors, that decide the EOvac revealed that bulk and surface-dependent descriptors are the most important, namely the bulk formation energy, a Boolean descriptor of whether the surface is (111) or not, and the ionization potential, followed by geometrical descriptors that are different in each O site.

Facial controlled synthesis of Pt/MnO2 catalysts with high efficiency for VOCs combustion.

Two sets of experiments were initially implemented to explore the best impregnation method and the best morphology substrate. In the first case, Pt/MnO2-r-WI catalyst showed a better performance than that of Pt/MnO2-r-IW. The test results illustrated that Wetness Impregnation (WI) could enhance the dispersion of Pt, ratios of Mn4+/Mn3+, Oads/Olatt and Pt4+/Pt0 as compared to those of Incipient Wetness Impregnation (IW). In the other method, MnO2-s catalyst displayed a higher catalytic efficiency than that of MnO2-r because the nanosphere morphology had larger BET surface area and pore volume to attract Pt atoms and toluene molecules. Therefore, the Pt/MnO2-s-WI catalyst was obtained and showed the best activity with low-temperature redox capability and oxygen mobility. It could eliminate toluene (T90) at a low temperature of 205 °C and remain stable over 150 h. effects of calcination temperature, toluene concentration and gas hourly space velocity (GHSV) were also investigated herein. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was also implemented to explore the reaction mechanism. It demonstrated that toluene was firstly adsorbed over Ptδ+ on the surface before being oxidized to CO2 and H2O. The whole procedure follows the Mars-van Krevelen mechanism. This work gives a comprehensive understanding of the heterogeneous catalysis mechanism.