To address the issues of insufficient activity and stability in transition metal catalysts for the catalytic oxidation of volatile organic compounds (VOCs), this study adopted a high-entropy strategy, successfully constructing a Mn-based high-entropy spinel oxide catalyst (Mn-HEO) through the doping of multiple metal atoms (Co, Mg, Zn, Cu) at the A site. Experimental results indicate that Mn-HEO exhibits significantly enhanced catalytic performance with a significant T90 reduction of 122 degrees C compared with Mn3O4. Stability test (450 degrees C) proves that Mn-HEO maintains 100% complete benzene conversion while Mn3O4 decreases to 80%. Combining characterization with density functional theory (DFT) calculations, high-entropy metal doping induces lattice distortion and electronic structure modulation in Mn-HEO, causing the d band center (-4.76 eV) to shift upward, significantly enhancing the adsorption capacity for gaseous oxygen (-2.83 eV) and benzene (-1.46 eV). Importantly, the surface chemical adsorption oxygen ratio of Mn-HEO is 1.15 times that of Mn3O4, and the O-O bond (1.48 & Aring;) is more prone to be weakened, promoting the activation and migration of oxygen species, thereby enhancing the catalytic activity of Mn-HEO.

Chemical Looping Combustion (CLC) is a combustion technology that enables efficient and low-energy CO2 capture. However, the cyclic regeneration capability of oxygen carriers represents a critical bottleneck restricting the development of this technology. This study investigates the CO chemical looping combustion (CO-CLC) behavior of inverse CeO2/Cu2O and pure Cu2O as oxygen carriers, focusing on lattice oxygen regeneration. DFT calculations and Redhead kinetics analyses pinpoint the Cu-Ce interface as the key promoter for oxygen activation. Electron transfer across this interface weakens Cu-O bonds, lowering both the oxygen vacancy formation energy to 2.54 eV at surface and the lattice oxygen migration barrier by 16 kJ/mol relative to pure Cu2O, which consequently improves the oxygen mobility markedly. The modified electronic structure, evidenced by a d-band center shift closer to the Fermi level, also weakens the adsorption of CO and O2 by 1.7 eV and 0.17 eV, thereby enhancing the overall reactivity. The Cu-Ce synergy enhances CO oxidation, oxygen activation/migration, and lattice oxygen replenishment, significantly boosting the cyclic regeneration capability of oxygen carriers.

Chemical looping combustion (CLC) is a promising technology for efficient CO2 capture. However, the intrinsic relationship between lattice oxygen migration and the cycling stability of oxygen carriers (OCs) remains insufficiently understood. In this study, we systematically investigated the structural evolution of Cu2O model OCs with well-defined morphologies, emphasizing the critical role of lattice oxygen migration in governing their cycling stability. Carbon monoxide (CO) was used as a probe molecule to induce the reduction of Cu2O, while oxygen (O2) facilitated its oxidation, thereby completing the CLC cycles. Cu2O in cubic and dodecahedral forms, which have closed surfaces, exhibit incongruent inward and outward lattice oxygen migration, triggering irreversible structural changes that ultimately result in ineffective cycles. In contrast, octahedral Cu2O, possessing an open surface and one-coordinate unsaturated Cu atoms, facilitates both CO oxidation and O2 activation. This open-surface configuration enables congruent lattice oxygen migration during redox cycling, thereby maintaining structural integrity and catalytic activity over ten consecutive cycles at 200 °C. These findings reveal a positive feedback mechanism between lattice oxygen migration and structural stabilization, providing fundamental insights into the origin of the superior cycling stability of well-defined Cu2O model OCs in CLC.

To meet the demand for simultaneous purification of multi-component volatile organic compounds (VOCs) from industrial emission sources, this study systematically investigated the catalytic oxidation behaviors of benzene, toluene and cyclohexane over regular Cu2O model catalysts, aiming to explore the mixing reaction mechanism.The results demonstrates that octahedral Cu2O possesses the best activity and competitive adsorption on the catalyst surface is the primary factor influencing the multi-component VOCs interactions. Specifically, toluene, due to its higher polarity, inhibits the benzene oxidation through competitive adsorption. Toluene and cyclohexane exhibit mutual promotion in catalytic oxidation attributing to the distinct adsorption configurations and weak competition. The cyclohexane oxidation generates benzene as a by-product, which increases benzene concentration and consequently suppresses its oxidation. DFT calculations reveals that toluene possesses the highest adsorption energy (-0.93 eV), followed by benzene (-0.86 eV) and cyclohexane (-0.52 eV), corresponding to the competitive adsorption ability. It should be noted that toluene shows the strongest hybridization between its molecular orbitals and Cu 3d and O 2p orbitals, leading to a reconfiguration of the electronic structure of the catalyst, which enhance the electron transfer efficiency and competitive advantage during the multi-component VOCs oxidation.

Tuning the oxygen vacancy concentration of non-noble metal catalysts is crucial for harnessing environmental catalytic oxidation reactions. Oxygen vacancy-induced reactive oxygen species (ROS) cycling capacity is modulated by catalyst modification using non-thermal plasma (NTP) for toluene oxidation. In this work, NTP treatment of spherical CuO/CeO2 catalysts accelerates electron transfer between Cu-O-Ce, resulting in the formation of more oxygen vacancies while maintaining the structural stability of the catalyst. This strategy facilitates the adsorption and activation of gaseous O2, generating highly mobile ROS that participate in the catalytic oxidation of toluene to form CO2. Compared with the untreated 7 %CuO/CeO2 catalyst (T90 = 272 degrees C), the NTPtreated 7 %CuO/CeO2-P exhibits a 41.5 % increase in oxygen vacancy concentration, along with improvements of 55.8 % and 54.7 % in oxygen storage and release performance, respectively, which ultimately unveil the remarkable toluene oxidation activity (T90 = 260 degrees C). Oxygen vacancy significantly enhances ROS mobility and reactivity, thereby accelerating the O2-OV-ROS cycling. Abundant oxygen vacancies allow an acceleration of the catalytic oxidation of toluene. This work provides a credible understanding of the catalyst performance enhancement achieved through NTP treatment of modified catalysts, which is effective in developing a pathway to enhance the catalytic oxidation activity of volatile organic compounds (VOCs).

The catalytic combustion of NH3 under fuel-rich conditions offers a promising route to carbon-neutral energy, but precise NOx suppression remains challenging due to competing redox pathways under extreme thermal gradients. Unlike steady-state NH3-SCR, this process involves dynamic Cu-site evolution in Cu/SSZ-13 catalysts. We elucidate the temperature-dependent mechanism of Cu species and develop a quantitative kinetic model linking Cu+ /Cu2+ valence transitions to NOx formation. Integrating quasi-in-situ XPS/AES, in-situ FTIR, synchrotron XAFS, and DFT calculations, we identify a critical "dynamic redox equilibrium window" (400-600 degrees C), where ammonia solvation mobilizes Cu species, enabling balanced Cu+/ Cu2+ coexistence. Isolated Cu+ sites drive rapid NO reduction via an E-R mechanism, while Cu2+ sites promote NH3 oxidation, achieving high N2 selectivity. Exceeding 600 degrees C induces catastrophic "selectivity collapse," triggered by lattice oxygen activation in Cu-oxo clusters (distinct from zeolite framework), which re-oxidizes Cu+ to static Cu2+ and causes a three-orderof-magnitude NO surge. Oxygen vacancy formation energy and O2 adsorption energy serve as key descriptors for this thermodynamic drive. Kinetic modeling shows rapid heating rates bypass this collapse, providing a practical startup strategy for low-NOx reactors.

Despite the excellent CO catalytic performance of Pt-0, it tends to suffer oxidation in real high-temperature environments, leading to decrease in activity. Therefore, it is necessary to study the catalytic performance of Pt-based catalysts in their unreduced state. In this study, the structure-activity relationship of high concentration CO oxidation over unreduced platinum supported catalysts (Pt/CeO2, Pt/TiO2, Pt/SnO2, Pt/ZrO2, Pt/La2O3) were investigated. The results indicate that due to the strong interaction between Pt and Ce, the valence changes of support element Ce facilitate the formation of redox pairs of Pt2+/Pt4+ and Ce3+/Ce4+ at the Pt-Ce interface, culminating in a catalytic activity superior to that of other catalysts. Furthermore, the O-18(2) isotope experiment achieved quantification of different lattice oxygens. Surface cycle lattice oxygen in the Pt/CeO2, possessing the highest Turnover Frequency (4.75 x10(-3) s(-1)), accounts for optimum catalytic activity. Both Mars-van Krevelen (M-K) mechanism and Langmuir-Hinshelwood (L-H) mechanism coexist in the CO catalytic oxidation, but the former predominates the reaction. The contribution proportion of the M-K mechanism decreases in the order of Pt/CeO2 (83 %) > Pt/TiO2 (79 %) > Pt/SnO2 (76 %) > Pt/ZrO2 (73 %) > Pt/La2O3 (70 %), which corresponds to the activity results.

The utilization of carbon-free NH3 gas can be extended from low-concentration environmental applications to high-concentration energy applications. To achieve this, minimizing NO formation while maximizing energy release is essential. In this study, we investigated the catalytic performance of catalysts with different acid site characteristics, including a non-acidic catalyst, CuO-CeO2 supported on TiO2 providing only Lewis acid (LA) sites, and a catalyst with both Brønsted acid (BA) and LA sites at the same active sites. These catalysts were used to examine the synergistic effects of BA and LA sites in NH3 catalytic combustion. Results show that proton transfer at BA sites, where H+ protonates NH3 to form NH+4, stabilizes NH3, reducing reactive NHx intermediates and enhancing NO reduction efficiency by interacting with N2O.In-situ impedance spectroscopy and diffuse reflectance infrared spectroscopy reveal that NH+4 formed on BA sites migrates, interacting with reductive NO species to prevent nitrate decomposition and limit NHx formation. The 18O2 isotope tracing of O species in NO reveals that NH+4 promotes NO conversion to N2 via an internal selective catalytic reduction (i-SCR) mechanism, maintaining NO concentrations below 50 ppm at temperatures below 550°C. Based on this specially designed catalyst, the combination of advanced in-situ analytical techniques and isotopic tracing highlights a crucial pathway for NH+4-mediated NOx reduction at acidic sites. The utilization of carbon-free NH3 gas can be extended from low-concentration environmental applications to high-concentration energy applications, requiring minimized NO formation alongside maximized energy release.

In recent years, the adsorption and separation of ammonia (NH3) from airflow have attracted growing attention. However, there is a need to further enhance the adsorption capacity of adsorbents. In this study, the aminofunctionalization of UiO-66 was investigated to evaluate its dynamic NH3 adsorption performance by varying the type and proportion of organic ligands. It was observed that the introduction of amino groups significantly enhanced the ammonia adsorption capacity by 78.5 %, despite a minor reduction in specific surface area and pore size. Combined with the results of density functional theory and in-situ infrared, the enhanced adsorption ability can be ascribed to the functionalization increasing the polarity within the pore, thereby strengthening interactions with ammonia molecules through weak hydrogen bonding.

VOCs oxidation over transition metal catalyst is commonly understood via the Mars-van Krevelen mechanism involving the crucial role of lattice oxygen (OL) activity, however, how it is influenced by atomic coordination is still unclear. Herein, we use model catalysts of Cu2O-cub, Cu2O-oct and Cu2O-dod with crystal planes of (100), (111) and (110), respectively, to investigate the OL activity and catalytic oxidation of toluene. The activity of Cu2O-oct is found to be the highest, followed by Cu2O-cub and Cu2O-dod. Experiments results combined with density functional theory show that, although low di-coordinated O atoms leads to the lowest surface oxygen vacancy formation energy (2.47eV) and the highest surface OL activity of Cu2O-cub, it cannot determine the activity. The lowest bulk oxygen vacancy formation energy (3.16eV) in Cu2O-oct terminated with tri-coordinated O atoms and open surface can accelerate the migration and replenishment of OL, thereby promoting the catalytic activity.

Cobalt-nickel-based catalysts are among the most promising non-noble metal catalysts for hydrogen production via ammonia decomposition. However, attaining the optimal bonding ratio at the CoNi alloy-support interface remains a significant challenge for ensuring sufficient catalytic activity in ammonia decomposition. To address this issue, this study investigates the enhancement of catalytic activity through the interface effects between CoNi alloy nanoparticles and different supports (ZSM-5, Al2O3, and TiO2), as well as the role of Lewis acid sites within the supports. It is found that the CoNi alloy particles supported on the carriers form CoNi-O bonds with oxygen atoms, creating an oxide-metal interface that facilitates charge transfer from the carrier to the alloy, promoting catalytic activity. In the CoNi/ZSM-5 catalyst, the abundant formation of CoNi-O bonds enhances the interfacial effects and promotes charge transfer, thereby improving catalytic performance. Besides, the plentiful Lewis acid sites in ZSM-5 improve the ammonia adsorption and the increasing local ammonia concentration ensures more effective contact and enhances catalytic efficiency.

The selective catalytic oxidation (SCO) has proved to be one of the most effective strategies for NH3 removal, and the corresponding reaction mechanism remains a key and challenging issue. This study provides the NH3-SCO reaction pathways at different reaction stages on Cu-Ce/SSZ-13 catalysts mainly based on kinetic experiments and quantitative analysis of active sites. Mars-van Krevelen (M-K) mechanism is determined to dominate the whole SCO reaction by the kinetic model. At low-temperature, the dehydrogenated NH3 (NHx) reacts with lattice oxygen first to generate the key imide -HNO (-NH pathway), whereas, NHx species tend to be coupled on the catalyst surface to form N2H4 (hydrazine pathway) with temperature rising. i-SCR reaction at high temperature reduces NOx production and improves nitrogen selectivity. Ce ions can promote the migration of Cu2+ in SSZ-13 skeleton from [Cu2+(OH)]+-Z in eight-membered rings to Cu2+-2Z in six-membered rings which facilitates the N2 selectivity at high temperature.

Studying the mechanisms of bagasse conversion into syngas is essential to sustain the growing use of biomass in energy economy production. In this work, the precise kinetics of bagasse gasification with various gasification agents was firstly investigated employing in-situ infrared spectra with Coats-Redfern integration, combining qualitative infrared spectroscopy allowed for kinetic analysis, so as to explore how the intermediate species vary in each basic reaction. The results demonstrate that the CO2 agent reduces the activation energy of nitryl after amino oxidation, making the lignin involved in gasification more easily as well as causing higher gasification efficiency. On the one hand, steam serving as a gasification agent enhances the concentration of hydroxyl groups and produces H2-rich syngas. On the other hand, the strong oxidizing hydroxyl group reduces the energy barrier of carbonyl and carboxyl groups in cellulose, which facilitates the gasification process. Furthermore, this study compared the effects of gasification agent (H2O or CO2) on syngas composition, reactor temperature distribution, carbon conversion rate, gasification efficiency, as well as low calorific value, providing essential information for understanding the micro-reaction pathways and pathway regulation during bagasse gasification.

Catalytic oxidation technology is a promising strategy to eliminate carbon monoxide (CO), volatile organic compounds (VOC) and other emissions from industrial boilers and to address ammonia (NH3) escape. Herein, we demonstrate the potential of copper-cerium-zirconium mixed oxides or those supported on TiO(2 )or ZSM-5 substrates for the simultaneous catalytic removal of CO, toluene and NH3. Among them, CuCeZr/ZSM-5 exhibits the best co-processing ability for mixed gases. In situ infrared spectroscopy analyses suggest that there is a competitive adsorption among CO, toluene and NH3, and the inhibition is in descending order of toluene>CO> NH3. Based on the physical-chemical characterizations, the Cu-Ce interfacial structure plays an important role in CO ignition at low temperatures. More importantly, the abundant acidic sites on the ZSM-5 support can improve the stability of adsorbed NH3 at high temperatures, resulting in the best NH3 catalytic oxidation performance of CuCeZr/ZSM-5 with no secondary pollutants of NOx. This study provides a strategy for the catalyst design to eliminate multiple pollutants targeting the properties of pollutants.

Adsorption is a promising strategy to remove harmful substances from Fischer-Tropsch synthesis (FTS) wastewater, and clarifying the adsorption mechanism is an important issue. In this paper, carbon nanotubes (CNTs) with different pore size were used for the adsorption of low-carbon alcohols (methanol, ethanol, propanol, butanol, pentanol) and acids (acetic acid, propanoic acid, butyric acid). After the micropores being occupied by chloroform, the percentage of micropores decrease is found to exhibit a positive correlation with adsorption capacity, indicating that the micropores dominanate the adsorption properties of alcohols and acids. Based on density functional theory (DFT) calculation results, the adsorption energy of pentanol is the largest and that of methanol is the smallest, in consistent with the experimental results. The similar polarity of pentanol with CNTs improves the adsorption property. Furthermore, with similar polarity, the kinetic diameter of adsorbate being close to the pore size is beneficial for improving adsorption behavior of CNTs.

Catalytic oxidation is a promising purification technique for ammonia (NH3) emission. However, high ignition temperatures and NOx peroxide generation limit its effectiveness due to a lack of active sites. Herein, the effects of Si/Al ratio (SAR) modulation on the speciation of copper active sites and the reaction mechanism at different acidic sites were investigated by loading CuO-CeO2 onto SSZ-13 with different SARs (Cu-Ce/SAR15, 20, and 30). Among them, Cu-Ce/SAR20 exhibits the lowest induction temperature (T-20 = 180 degrees C) and the highest nitrogen selectivity (above 95%), attributing to a higher number of Cu2+ exchange sites. In situ IR spectroscopy and isotopic (O-18(2)) transient response experiments indicate that more active Cu2+ in Cu-Ce/SAR20 provides sufficient Lewis acidic sites for NH3 adsorption and favors the stability of Si-OH-Al structures (Br & oslash;nsted acid sites). NH3 adsorbed at Lewis acidic sites tends to form peroxide byproducts (NOx), while the NH4+ adsorbed at Br & oslash;nsted acidic sites generates the key intermediate NH4NO2, which decomposes to N-2 at high temperatures, thus enhancing nitrogen selectivity. The whole process mainly follows the Mars-van Krevelen (M-K) mechanism, with the Langmuir-Hinshelwood (L-H) mechanism playing a supporting role. Z(2)Cu(2+) coordinates with adjacent Al atoms within the six-membered ring (6MR) and undergoes a slight deformation at high temperatures, facilitating the migration of the lattice oxygen. SAR plays a crucial role in local environmental speciation of reactive Cu2+, where the sufficient isolated Al provided in SAR20 pulls Cu2+ into the eight-membered ring (8MR), allowing it to come into contact with NH3 more readily.

Utilizing environmentally-friendly bacterial cellulose as a scaffold, a highly porous, layered OA-BC catalyst was synthesized through an enhanced sol-gel process. This catalyst demonstrated exceptional performance in the oxidation of toluene, outperforming conventional alternatives that utilize chemical porogens. The OA-BC catalyst efficiently degrades toluene at 220℃ with high stability and hydrophobicity, indicating resistance to deactivation. Its superior activity is due to increased oxygen vacancies, enhanced metal oxide cooperation, and a layered porous structure, which together enhance active oxygen species and oxygen diffusion. Calcination of the OA-BC catalyst results in molecular cleavage and formation of small aggregates, increasing hydroxyl groups that stabilize Cu and Ce centers, enhancing toluene-oxygen reactions. In-situ infrared and X-ray photoelectron spectroscopy confirm stable monodentate Cu+ ligands, contributing to its high catalytic activity. This study introduces a novel approach by employing bacterial cellulose as a template for synthesizing a porous stratified OA-BC catalyst, demonstrating superior performance in toluene oxidation. The efficacy of catalyst results from a tripartite synergy involving the stratified porous architecture, the stabilizing effect of Cu+-coordinating ligands and hydroxyl groups, and the interplay of hydroxyl electron donors and acceptors, shedding light on environmentally benign catalyst development.

CuO/CeO2 catalysts were widely studied as an alternative to precious metal catalysts, and the Cu–Ce synergy was essential to improve the catalytic performance.

Plasma catalysis is recognized as a promising technology for the elimination of diluted volatile organic compounds (VOCs).