Promoting C-Cl Bond Activation via a Preoccupied Anchoring Strategy on Vanadia-Based Catalysts for Multi-Pollutant Control of NOx and Chlorinated Aromatics.

Regulating vanadia-based oxides has been widely utilized for fabricating effective difunctional catalysts for the simultaneous elimination of NOx and chlorobenzene (CB). However, the notorious accumulation of polychlorinated species and excessively strong NH3 adsorption on the catalysts lead to the deterioration of multipollutant control (MPC) activity. Herein, protonated sulfate (-HSO4) supported on vanadium-titanium catalysts via a preoccupied anchoring strategy are designed to prevent polychlorinated species and alleviate NH3 adsorption for the multipollutant control. The obtained catalysts with -HSO4 modification achieve an excellent NOx and CB conversion with turnover frequency values of ∼ 3.63 and 17.7 times higher than those of the pristine, respectively. The protonated sulfate promotes the formation of polymeric vanadyl with a higher chemical state and d-band center of V. The modulated catalysts not only substantially alleviate the competitive adsorption of multipollutant via the "V 3d-O 2p-S 3p" network, but also distinctly strengthen the Brønsted acid sites. Besides, the introduced proton donor of the -HSO4 connecting polymeric structure could markedly reduce the reaction barrier of breaking the C-Cl bond. This work paves an advanced way for low-loading vanadium SCR catalysts to achieve highly efficient NOx and CB oxidation at a low temperature.

Promoting effect of Cu as electron transfer medium on NH3-SCO reaction in asymmetric Ag-Ov-Ti-Sm-Cu ring active site.

Selective catalytic oxidation of ammonia (NH3-SCO) has become an effective method to reduce ammonia (NH3) emissions, and is a key part to solve the problem of NH3 pollution. Nevertheless, the optimization of this technology's performance relies heavily on innovation and the development of catalyst design. In this study, a SmCuAgTiOx catalyst with an asymmetric Ag-Ov-Ti-Sm-Cu ring active site was prepared and applied to the NH3-SCO reaction. The low conversion of Cu-based catalysts in NH3 at low temperature and the inherent low N2 selectivity of Ag-based catalysts were solved. The successful creation of the asymmetric ring active site improved the catalyst's reduction performance. Additionally, Cu, acting as an electron transfer medium, plays a crucial role in enhancing electron transfer within the asymmetric ring active site, thus increasing the redox cycle of the catalyst during the reaction. In addition, some lattice oxygen is lost in the catalyst, resulting in the formation of a large number of oxygen vacancies. This process stimulates the adsorption and activation of surface-adsorbed oxygen, facilitating the conversion of NH3 to an amide (NH2) intermediate during the reaction and reducing non-selective oxidation. The N2 selectivity was improved without significantly affecting the performance of Ag-based catalyst. In-situ diffuse reflectance fourier transform infrared spectroscopy (In-situ DRIFTS) analysis reveals that the SmCuAgTiOx catalyst primarily follows an "internal" selective catalytic reduction (iSCR) mechanism in the NH3-SCO reaction, complemented by the imide mechanism. The asymmetric Ag-Ov-Ti-Sm-Cu ring active site developed in this study provides a new perspective for efficiently solving NH3 pollution in the future.

Nonstoichiometry Induced Amorphous Grain Boundary of Na5SmSi4O12 Solid-State Electrolyte for Long-Life Dendrite-Free Sodium Metal Battery.

Oxide ceramics are considered promising candidates as solid electrolytes (SEs) for sodium metal batteries. However, the high sintering temperature induced boundaries and pores between angular grains lead to high grain boundary resistance and pathways for dendrite growth. Herein, we report a grain boundary modification strategy, which in situ generates an amorphous matrix among Na5SmSi4O12 oxide grains via tuning the chemical composition. The mechanical properties as well as electron mitigating capability of modified SE have been significantly enhanced. As a result, the SE achieves a room-temperature total ionic conductivity of 5.61 mS cm-1, the highest value for sodium-based oxide SEs. The Na|SE|Na symmetric cell achieves a high critical current density of 2.5 mA cm-2 and excellent cycle life over more than 2800 h at 0.15 mA cm-2 without dendrite formation. The full cell with Na3V2(PO4)3 as the cathode demonstrates impressive cycling performance, maintaining stability over 3000 cycles at 5C without observable loss of capacity.

Insights into in situ surface reconstruction in cobalt perovskite oxides for enhanced catalytic activity.

An depth understanding of the fundamental interactions between surface termination and catalytic activity is crucial to prompt the properties of functional perovskite materials. The elastic energy due to size mismatch and electrostatic attraction of the charged Sr dopant by positively charged oxygen vacancies induced inert A-site surface enrichment rearrangement for perovskites. Lower temperatures could reduce A-site enrichment, but it is difficult to form perovskite crystals. La0.8Sr0.2CoO3-δ (LSCO) as a model perovskite oxide was modified with additive urea to reduce the crystallization temperature, and suppress Sr segregation. The LSCO catalysts with 600 °C annealing temperature (LSCO-600) exhibited a 19.4-fold reaction reactivity of toluene oxidation than that with 800 °C annealing temperature (LSCO-800). Combined surface-sensitive and depth-resolved techniques for surface and sub-surface analysis, surface Sr enrichment was effectively suppressed due to decreased oxygen vacancy concentration and smaller electrostatic driving force. DFT calculations and in-situ DRIFTs spectra well revealed that tuning the surface composition/termination affected the intrinsic reactivity. The catalyst surface with lower Sr enrichment could easily adsorb toluene, cleave, and decompose benzene rings, thus contributing to toluene degradation to CO2. This work demonstrates a green and efficient way to control surface composition and termination at the atomic scale for higher catalytic activity.

Phosphorus-Water Interaction Drives Active Center Evolution into the Water-Adaptive Structure in the High-Humidity NH3-SCR Reaction.

The impact of water on catalyst activity remains inconclusive due to its dependence on the specific reaction environment. To maximize the exploitation of water's promoting effect, we employed ammonia selective catalytic reduction (NH3-SCR) as a probe reaction and proposed a phosphorus modification strategy for Cu-ZSM-5 catalysts. The objective of this approach was to construct water-adaptive microstructures through directional arrangement. To investigate the effect of phosphorus on the transformation of framework copper sites in humid environments, we conducted comprehensive characterizations and density functional theory calculation. Results reveal that water molecules cleave the oxygen bridges between phosphorus oxide and copper, leading to the formation of active isolated [Cu(OH)]+ groups and phosphate. The phosphate species weaken the interaction between exchanged Cu2+ groups and the zeolite framework, leading to the generation of highly migratory hydrated Cu2+ species. This work will potentially guide the rational design of water-adaptive catalysts for gas pollution abatement in a humid environment.

Positive feedback regulation between glycolysis and histone lactylation drives oncogenesis in pancreatic ductal adenocarcinoma.

BACKGROUND: Metabolic reprogramming and epigenetic alterations contribute to the aggressiveness of pancreatic ductal adenocarcinoma (PDAC). Lactate-dependent histone modification is a new type of histone mark, which links glycolysis metabolite to the epigenetic process of lactylation. However, the role of histone lactylation in PDAC remains unclear. METHODS: The level of histone lactylation in PDAC was identified by western blot and immunohistochemistry, and its relationship with the overall survival was evaluated using a Kaplan-Meier survival plot. The participation of histone lactylation in the growth and progression of PDAC was confirmed through inhibition of histone lactylation by glycolysis inhibitors or lactate dehydrogenase A (LDHA) knockdown both in vitro and in vivo. The potential writers and erasers of histone lactylation in PDAC were identified by western blot and functional experiments. The potential target genes of H3K18 lactylation (H3K18la) were screened by CUT&Tag and RNA-seq analyses. The candidate target genes TTK protein kinase (TTK) and BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) were validated through ChIP-qPCR, RT-qPCR and western blot analyses. Next, the effects of these two genes in PDAC were confirmed by knockdown or overexpression. The interaction between TTK and LDHA was identified by Co-IP assay. RESULTS: Histone lactylation, especially H3K18la level was elevated in PDAC, and the high level of H3K18la was associated with poor prognosis. The suppression of glycolytic activity by different kinds of inhibitors or LDHA knockdown contributed to the anti-tumor effects of PDAC in vitro and in vivo. E1A binding protein p300 (P300) and histone deacetylase 2 were the potential writer and eraser of histone lactylation in PDAC cells, respectively. H3K18la was enriched at the promoters and activated the transcription of mitotic checkpoint regulators TTK and BUB1B. Interestingly, TTK and BUB1B could elevate the expression of P300 which in turn increased glycolysis. Moreover, TTK phosphorylated LDHA at tyrosine 239 (Y239) and activated LDHA, and subsequently upregulated lactate and H3K18la levels. CONCLUSIONS: The glycolysis-H3K18la-TTK/BUB1B positive feedback loop exacerbates dysfunction in PDAC. These findings delivered a new exploration and significant inter-relationship between lactate metabolic reprogramming and epigenetic regulation, which might pave the way toward novel lactylation treatment strategies in PDAC therapy.

Tuning Pd species via electronic metal-support interaction for methane combustion.

Utilizing catalytic combustion to convert methane (CH4) into CO2 and H2O stands as one of the most effective approaches for mitigating unburnt CH4 emissions from natural gas engines. Supported Pd catalysts have been extensively researched for their role in low-temperature CH4 combustion, with their catalytic activity greatly influenced by metal-support interactions. Surface interaction Pd phases, as a special type of Pd species originating from metal-support interactions on supported Pd catalysts, show controversial catalytic performance in CH4 combustion. Moreover, the impact of electronic metal-support interactions (EMSI, which refers to metal-support interactions associated with electron transfer) remains unclear. Hence, we opted for Ce-Zr solid solutions with different Ce:Zr molar ratios as supports and synthesized a range of supported Pd catalysts with varying EMSI intensities. Characterization revealed that as the oxygen vacancy concentration on the support increased, electron transfer weakened, leading to a higher Pd-O-Ce content, resulting in a lower CH4 activation barrier and better catalytic performance. This study offers a promising approach for regulating EMSI and active Pd species on supported catalysts in practical applications.

Essential role of lattice oxygen in hydrogen sensing reaction.

Understanding the sensing mechanism of metal oxide semiconductors is imperative to the development of high-performance sensors. The traditional sensing mechanism only recognizes the effect of surface chemisorbed oxygen from the air but ignores surface lattice oxygen. Herein, using in-situ characterizations, we provide direct experimental evidence that the surface chemisorbed oxygen participated in the sensing process can come from lattice oxygen of the oxides. Further density functional theory (DFT) calculations prove that the p-band center of O serves as a state of art for regulating the participation of lattice oxygen in gas-sensing reactions. Based on our experimental data and theoretical calculations, we discuss mechanisms that are fundamentally different from the conventional mechanism and show that the easily participation of lattice oxygen is helpful for the high response value of the materials.

Enhancing CO catalytic oxidation performance over Cu-doping manganese oxide octahedral molecular sieves catalyst.

The CO oxidation catalytic activity of catalysts is strongly influenced by the oxygen vacancy defects (OVDs) concentration and the valence state of active metal. Herein, a defect engineering approach was implemented to enhance the oxygen vacancy defects and to modify the valence of metal ions in manganese oxide octahedral molecular sieves (OMS-2) by the introduction of copper (Cu). The characterization and theoretical calculation results reveal that the incorporation of Cu2+ ion into the OMS-2 structure led to a rise in specific surface area and pore volume, weakening of Mn-O bonds, higher proportion of the low-coordinated oxygen species adsorbed in oxygen vacancies (Oads) and an increase in the average oxidation state of manganese. These structural modifications were discovered to considerably reduce the apparent activation energy (Ea), thus ultimately significantly enhancing the CO oxidation activity (T99 at 148 ℃at GHSV = 13,200 h-1) than the original OMS-2 (T99 = 215 ℃ at GHSV = 13,200 h-1). Furthermore, In-situ diffuse reflectance infrared Fourier transform (DRIFT) and In-situ near-ambient pressure X-ray photoelectron spectroscopy (in situ NAP-XPS) results indicate that the bimetallic synergy enhanced by doping strategy accelerates the conversion of oxygen to chemisorbed oxygen species and the reaction rate of CO oxidation through Mn3++Cu2+↔Mn4++Cu+ redox cycle. The findings of this study offer novel perspectives on the design of catalysts with exceptional performance in CO oxidation.

Influence of Oxygen Vacancy-Induced Coordination Change on Pd/CeO2 for NO Reduction.

The byproduct formation in environmental catalysis is strongly influenced by the chemical state and coordination of catalysts. Herein, two Pd/CeO2 catalysts (PdCe-350 and PdCe-800) with varying oxygen vacancies (Ov) and coordination numbers (CN) of Pd were prepared to investigate the mechanism of N2O and NH3 formation during NO reduction by CO. PdCe-350 exhibits a higher density of Ov and Pd sites with higher CN, leading to an enhanced metal-support interaction by electron transformation from the support to Pd. Consequently, PdCe-350 displayed increased levels of byproduct formation. In situ spectroscopies under dry and wet conditions revealed that at low temperatures, the N2O formation strongly correlated with the Ov density through the decomposition of chelating nitro species on PdCe-350. Conversely, at high temperatures, it was linked to the reactivity of Pd species, primarily facilitated by monodentate nitrates on PdCe-800. In terms of NH3 formation, its occurrence was closely associated with the activation of H2O and C3H6, since a water-gas shift or hydrocarbon reforming could provide hydrogen. Both bridging and monodentate nitrates showed activity in NH3 formation, while hyponitrites were identified as key intermediates for both catalysts. The insights provide a fundamental understanding of the intricate relationship among the local coordination of Pd, surface Ov, and byproduct distribution.

Anti-Poisoning Mechanisms of Sb on Vanadia-Based Catalysts for NOx and Chlorobenzene Multi-Pollutant Control.

Modulating vanadia-based metal oxides is one of the effective methods for designing difunctional catalysts for simultaneous control of NOx and chlorobenzene (CB) from the emissions of industrial sources. Excessive NH3 adsorption and polychlorinated species accumulation on the surface are the primary issues poisoning catalysts and reducing their lifetime. Herein, Sb is selected as an NH3 adsorption alleviator and polychlorinated species preventor dopant on V2O5-WO3/TiO2. The catalyst exhibits an excellent performance for total NOx and 90% CB conversions at 300-400 °C under a gas hourly space velocity (GHSV) of 60,000 mL g-1 h-1. The HCl and N2 selectivities are maintained at 90 and 98%, respectively. The anti-poisoning ability could be attributed to the generated V-O-Sb chains on the surface: the band gap of vanadium is narrowed and the electron capability is strengthened. The above variation weakens the Lewis acid sites and blocks the electrophilic chlorination reactions of the catalyst surface (formation of polychlorinated species). In addition, oxygen vacancies on Sb-O-Ti also increase: the ring opening of benzoates is accelerated and NH3 adsorption energy is weakened. The above variation lowers the energy barriers of C-Cl cleavage even under NH3 pre-adsorption models and enhances NOx reduction thermodynamically and kinetically.

Novel Insights on the Metal-Support Interactions of Pd/ZrO2 Catalysts on CH4 Oxidation.

With the environmental harm of unburnt CH4 in natural gas vehicle exhaust, oxidizing CH4 to CO2 over catalysts at low temperatures becomes an exigent issue. Supported Pd catalysts possess higher CH4 activity than other noble metal catalysts. A series of Pd/ZrO2 catalysts were synthesized to research the potential relationship among Pd particle morphology, electron transfer, CH4 oxidation mechanism, and catalytic activity. Characterizations show that the ratio of PdOx facets to edge/corner sites on four catalysts increases in the order of PZ85 ≈ PZ40 < PZ55 < PZ70 because of the difference in content of surface -OH groups, and this order turns out to be the same as that of electron transfer intensity, revealing the degree of metal-support interactions. This kind of metal-support interaction in PZ70 can be helpful to accelerate CH4 combustion via promoting the break of the C-H bond and dissociation of CO3* according to density functional theory studies. T90 of the PZ70 catalyst with optimum catalytic activity reaches 331 °C.

Boosting CO Catalytic Oxidation Performance via Highly Dispersed Copper Atomic Clusters: Regulated Electron Interaction and Reaction Pathways.

Copper-loaded ceria (Cu/CeO2) catalysts have become promising for the catalytic oxidation of industrial CO emissions. Since their superior redox property mainly arises from the synergistic effect between Cu and the CeO2 support, the dispersion state of Cu species may dominate the catalytic performance of Cu/CeO2 catalysts: the extremely high or low dispersity is disadvantageous for the catalytic performance. The nanoparticle catalysts usually present few contact sites, while the single-atom catalysts tend to be passivated due to their relatively single valence state. To achieve a suitable dispersion state, we synthesized a superior Cu/CeO2 catalyst with Cu atomic clusters, realizing high atomic exposure and unit atomic activity simultaneously via favorable electron interaction and an anchoring effect. The catalyst reaches a 90% CO conversion at 130 °C, comparable to noble-metal catalysts. According to combined in situ spectroscopy and density functional theory calculations, the superior CO oxidation performance of the Cu atomic cluster catalyst results from the joint efforts of effective adsorption of CO at the electrophilic sites, the CO spillover phenomenon, and the efficient bicarbonate pathway triggered by hydroxyl. By providing a superior atomic cluster catalyst and uncovering the catalytic oxidation mechanism of Cu-Ce dual-active sites, our work may enlighten future research on industrial gaseous pollutant removal.

Advances in the treatment of multi-pollutant flue gas in China's building materials industry.

In most of the world's building material industries, the control of flue gas pollutants mainly focuses on a single pollutant. However, given the large capacity and high contribution of China's building materials industry to global air pollution, the need to develop multi-pollutant emission reduction technology is urgent. Recently, China has focused on reducing the emissions of flue gas pollutants in the building materials industry, established many key research and development projects, and gradually implemented more stringent pollutant emission limits. This project focuses on the most recent advances in flue gas emission control technology in China's building materials industry, including denitration, dust removal, desulfurization, synergistic multi-pollutant emission reduction, and the construction of pilot research and demonstration projects for pollutant removal in several building material industries. On this basis, revised pollutant limits in flue gas emitted in China's building material industry are proposed.

Defect Engineering on CuMn2O4 Spinel Surface: A New Path to High-Performance Oxidation Catalysts.

Catalytic combustion is an efficient method to eliminate CO and volatile organic compound (VOC) pollutants. CuMn2O4 spinel is a high-performance non-noble metal oxide catalyst for catalytic combustion and has the potential to replace noble metal catalysts. In order to further improve the catalytic activity of CuMn2O4 spinel, we propose a simple and low-cost approach to introduce numerous oxygen and metal vacancies simultaneously in situ on the CuMn2O4 spinel surface for the catalytic combustion of CO and VOCs. Alkali treatment was used to generate oxygen vacancies (VO), copper vacancies (VCu), and novel active sites (VO combines with Mn2O3 at the interface between Mn2O3(222) and CuMn2O4(311)) on the CuMn2O4 spinel surface. In the catalytic combustion of CO and VOCs, the vacancies and new active sites showed high activity and stability. The oxidation rate of CO increased by 4.13 times at 160 °C, and that of toluene increased by 11.63 times at 250 °C. Oxygen is easier to adsorb and dissociate on VO and novel sites, and the dissociated oxygen also more easily participates in the oxidation reaction. Furthermore, the lattice oxygen at VCu more readily participates in the oxidation reaction. This strategy is beneficial for the development of defect engineering on spinel surfaces and provides a new idea for improving the catalytic combustion activity of CuMn2O4 spinel.

Pulmonary mucoepidermoid carcinoma in the Chinese population: A clinical characteristic and prognostic analysis.

Background: Mucoepidermoid carcinoma is dominant in salivary glands and rarely occurs in the lung. Primary pulmonary mucoepidermoid carcinoma is a type of non-small-cell lung cancer, but the prognostic factors in Chinese patients remain controversial. This investigation aimed to review cases of pulmonary mucoepidermoid carcinoma, analyse the prognosis of this disease. Methods: Patients with pathologically proven pulmonary mucoepidermoid carcinoma were screened at the Department of Respiratory and Critical Care Medicine at the Peking University Third Hospital, Beijing Friendship Hospital Affiliated to Capital Medical University, and Peking University Cancer Hospital for inclusion in this retrospective study. Demographic data, including age, sex, clinical symptoms, smoking, alcohol consumption, allergies, family history, imaging findings, fibrobronchoscopy findings, surgical procedures, tumour location and pathologic stage, were collected. Telephone follow-up was conducted for all patients not lost to follow-up. The associations of sex, age, smoking, tumour differentiation, tumour size, lymph node metastasis, pathologic stage, and patient survival were retrospectively analysed. Kaplan-Meier, univariate and multivariate analysis curves were used to analyse patient prognosis and prognostic factors. Results: Thirty-one patients, comprising 23 males and 8 females, were enrolled in the analysis. The mean age was 60.77 ± 11.44 years. The first symptom was nonspecific, with cough being the most common (21/31, 67.77%); smokers accounted for 16 of the 31 patients, and ten patients had a history of alcohol consumption. Overall, the tumours could occur in either lobe of the lungs; tumours occurred in the right lung in 19/31 patients, and tumours occurred in the left lung in 12/31 patients. Regarding TNM stage, 10 patients had stage I (5 with stage 1a, 5 with stage 1b), 5 had stage II (1 with stage 2a, 4 with stage 2b), 3 had stage III (1 with stage 3a, 2 with stage 3b), and 13 had stage IV (10 with stage 4a, 3 with stage 4b). In our Cox univariate survival analysis of patients with pulmonary mucoepidermoid carcinoma, we found that TNM stage IV, degree of differentiation and lymph node metastasis were risk factors for pulmonary mucoepidermoid carcinoma and that degree of differentiation was an independent risk factor. Conclusion: The clinical, radiographical and pathological features of pulmonary mucoepidermoid carcinoma were systemically analysed and summarized, and the degree of differentiation and lymph node metastasis, as well as prognostic factors in addition to clinical stage, were confirmed.

[Genetic analysis of a child with glycogen storage disease type IXa due to a novel variant in PHKA2 gene].

OBJECTIVE: To explore the genetic etiology of a patient with glycogen storage diseases. METHODS: Clinical data of child and his parents were collected. The genes associated with glycogen storage diseases were subjected to high-throughput sequencing to screen the variants. Candidate variant was validated by Sanger sequencing. Pathogenicity of the variant was predicted by bioinformatic analysis. RESULTS: High-throughput sequencing results showed that the boy has carried a hemizygous c.749C>T (p.S250L) variant of the PHKA2 gene. Sanger sequencing verified the results and confirmed that it was inherited from his mother. This variant was unreported previously and predicted to be pathogenic by bioinformatic analysis. CONCLUSION: The patient was diagnosed with glycogen storage disease type IXa due to a novel c.749C>T (p.S250L) hemizygous variant of the PHKA2 gene. High-throughput sequencing can facilitate timely and accurate differential diagnosis of glycogen storage disease type IXa.

Interaction Mechanism for Simultaneous Elimination of Nitrogen Oxides and Toluene over the Bifunctional CeO2-TiO2 Mixed Oxide Catalyst.

Simultaneous catalytic elimination of nitrogen oxides (NOx, x = 1 and 2) and volatile organic compounds (VOCs) is of great importance for environmental preservation in China. In this work, the interactions of simultaneous removal of NOx and methylbenzene (PhCH3) were investigated on a CeO2-TiO2 mixed oxide catalyst, which demonstrated excellent bifunctional removal efficiencies for the two pollutants. The results indicated that NOx positively promotes PhCH3 oxidation, while NH3 negatively inhibits through competitive adsorption with PhCH3. The underlying mechanism is that a pseudo PhCH3-SCR reaction happened in this process is parallel to NH3-SCR. Combined with in situ diffuse reflectance infrared Fourier transform spectroscopy and quasi in situ X-ray photoelectron spectroscopy, the interaction mechanism between NOx and PhCH3 is proposed. Specifically, NOx is adsorbed on the catalyst surface to produce nitrate species, which reacts with the carboxylate generated during PhCH3 oxidation to form organic nitrogen intermediates that create N2 and CO2 in the following reactions. In the reaction process, the superoxide (O2-) generated by O2 activation on the catalyst surface is an important species for the propelling of oxidation reaction. This work could provide guidelines for the design of state-of-the-art catalysts for simultaneous catalytic removal of NOx and VOCs.

Like Cures like: Detoxification Effect between Alkali Metals and Sulfur over the V2O5/TiO2 deNOx Catalyst.

The V2O5/TiO2 (VTi) catalyst has been widely employed for the NH3 selective catalytic reduction (NH3-SCR) reaction, and sulfur (S) and alkali metals (K) were usually considered as poisons during this reaction. In this work, the synergistic effect of S and K over the VTi catalyst for the NH3-SCR reaction was analyzed and discussed. It is surprisingly observed that the synergistic effects of S and K exhibited a detoxification effect on the NH3-SCR reaction. That is, although the VTi catalyst exhibited moderate resistance to S poisoning and unsatisfactory resistance to K deactivation, the SCR activity was restored to close to fresh VTi when K and S coexisted. This detoxification effect also could occur between other alkali metals (e.g., Ca and Na) and sulfur. X-ray photoelectron spectroscopy and charge density difference studies both indicate that the introduction of K could significantly affect the electronic structure of V, but this toxic effect was recovered by the further addition of S because of the strong interaction between S and K. Therefore, this detoxification effect can occur in the practical reaction atmosphere, which alleviates the alkali metal poisoning of commercial catalysts.

Synergistic Effects of a CeO2/SmMn2O5-H Diesel Oxidation Catalyst Induced by Acid-Selective Dissolution Drive the Catalytic Oxidation Reaction.

A diesel oxidation catalyst (DOC) is installed upstream of an exhaust after-treatment line to remove CO and hydrocarbons and generate NO2. The catalyst should possess both good oxidation ability and thermal stability because it sits after the engine. We present a novel high-performance DOC with high steam resistance and thermal stability. A selective dissolution method is adopted to modify the surface physicochemical environment of CeO2-SmMn2O5. The X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, Raman, electron paramagnetic resonance, hydrogen temperature-programmed reduction, and temperature-programmed desorption results reveal that surface Sm cations are partially removed with the exposure of more Mn4+ and Ce3+ cations and the presence of active surface oxygen species. This mechanism benefits the oxygen transformation from Ce to Mn and promotes the Ce3+ + Mn4+ ↔ Ce4+ + Mn3+ redox cycle according to the in situ near-ambient pressure X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transformation spectroscopy results. Under laboratory-simulated diesel combustion conditions, the catalyst demonstrates excellent low-temperature oxidation catalytic activity (CO and C3H6 conversion: T100 = 250 °C) compared to a Pt-based catalyst (CO and C3H6 conversion: T100 = 310 °C) with a WHSV of 120,000 mL g-1 h-1. Specifically, NO conversion reaches 68% when the temperature is approximately 300 °C.