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Studies the use of layered lanthanum-barium-copper (La-Ba-Cu) mixed oxides with perovskite structure as catalyst for nitrogen oxygen (NO) reduction by cobalt (Co). Comparison of structures of three samples and simple ABO3; Valence of Cu ions ; Structure data of LaBa2Cu3O7; Importance of Cu.

CH4 and CO oxidation reaction on perovskite-like oxides La2-xSrxMO4 (0.0⩽x⩽1.0; M = Cu, Ni) was investigated from cyclic voltammetry method, finding that for suprafacial CO oxidation reaction, the catalyst activity has a close correlation to the area of redox peaks measured in the cyclic voltammetry, the larger the peak area is, the higher the activity will be, while for interfacial CH4 oxidation reaction, the activity depends mainly on the difference in redox potentials (ΔE), and the smaller the difference in redox potentials is, the higher the activity will be. [ABSTRACT FROM AUTHOR]

Ce-based selective catalytic reductions with an NH3 (NH3-SCR) catalyst have emerged as a focal point in denitrification catalyst research. However, the correlation between the structural characteristics of Ce-based catalysts and the influence of CeO2 nanoparticle size on SO2 resistance remains unclear. CeO2 nanospheres with different sizes of less than 10 nm were synthesized, and a series of supported CeO2/SBA-15 catalysts were prepared according to the 10 nm pore size of SBA-15. These catalysts were used to explore the influence of the size of the CeO2 nanospheres on these catalysts, specifically on their SO2 resistance in NH3-SCR reactions. With the increase in size, their SO2 resistance became stronger. The results of NH3-TPD, H2-TPR, and XPS indicated that the catalyst with the largest particle size had the lowest adsorption of SO2, which was attributed to more acid sites and a mutual effect between Si and Ce, resulting in the best SO2 resistance. It was also observed that there was less sulfate deposition on the catalyst by thermogravimetric analysis. In situ DRIFTs revealed that after SO2 poisoning, the NH3-SCR reaction on the catalyst predominantly follows the E-R mechanism. This study offers recommendations for the development of Ce-based SO2-resistant NH3-SCR catalysts, specifically focusing on the synthesis and interaction of nanomaterials. [ABSTRACT FROM AUTHOR]

A series of bimetallic CuNi/SSZ-13 catalysts with various Cu/Ni ratios were successfully synthesized via a one-pot hydrothermal route by using nickel-diethylenetriamine (Ni-DETA) and copper-tetraethylenepentamine (Cu-TEPA) as co-templates. Significantly, thanks to the introduction of Ni species which could inhibit the formation of copper oxides, bimetallic CuNi/SSZ-13 catalysts show enhanced performance for selective catalytic reduction of NO x with NH 3 compared with Cu/SSZ-13 counterpart. The addition of nickel into Cu/SSZ-13 contributes to enhanced NH 3 -SCR performance at high temperature due to inhibition of formation of copper oxides upon the introduction of nickel species in the catalysts. Unlabelled Image • A nickel-diethylenetriamine complex (Ni-DETA) acts as template to prepare Ni/SSZ-13 zeolites by in situ hydrothermal synthesis method. • Bimetallic CuNi/SSZ-13 catalysts exhibit enhanced NH 3 -SCR performance at high temperature due to the inhibition of formation of copper oxides upon the introduction of nickel species in the catalyst. • The introduction of a small amount of nickel could promote the high temperature catalytic performance under the premise of ensuring low temperature activity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The catalyst configuration Played a vital role in designing a highly efficient catalyst for exhaust purification. • The dual layer catalyst system can well combine the Selective catalytic reduction(SCR) with soot combustion. • NPt@CeO 2 /MCM-56 and CeO 2 -CuO (9:1)/MCM-56 could be combined to purify the exhaust emissions from diesel vehicles with configuration A. Abstract Pt@CeO 2 /MCM-56 (PCM) and CeO 2 -CuO (9:1)/MCM-56 (CCM) were combined to purify the exhaust emissions from diesel vehicles in three configuration statuses, defined as configuration A—where CCM stays above PCM, configuration B—where PCM stays above CCM, and configuration C—where CCM mixes with PCM homogeneously in loose contact. Among these combined catalysts, the configuration A is most favorable for the selective catalytic reduction (SCR) reaction, with >80% NO x conversion obtained at the temperature range of 150–550 °C and gas hourly space velocity (GHSV) of 240,000 ml g−1 h−1. NH 3 -TPD, H 2- TPR and NH 3 conversion measurements demonstrated that NH 3 can be selectively used to reduce NO x in the configuration A but is over-oxidized if the reaction is operated in configuration B or configuration C status, deteriorating the deNO x activity at temperature above 250 °C. Hence, configuration A not only takes advantage but also overcomes the shortcomings of PCM and CCM, leading to high NO x conversion and N 2 selectivity. A significant decrease in the onset temperature of soot combustion was also observed in this research. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of NO x with CO (CO-SCR) is a process that purifies both NO and CO pollutants through a catalytic reaction. Specifically, the cleavage of NO on the catalyst surface is crucial for promoting the reaction. During the reaction, the presence of oxygen vacancies can extract oxygen from NO, thereby facilitating the cleavage of NO on the catalyst surface. Thus, the formation of oxygen vacancies is key to accelerating the CO-SCR reaction, with different types of oxygen vacancies being more conducive to their generation. In this study, Rh/CeCuO x catalysts were synthesized using the co-crystallization and impregnation methods, and asymmetric oxygen vacancies were induced through hydrogen thermal treatment. This structural modification was aimed at regulating the behavior of NO on the catalyst surface. The Rh/Ce 0.95 Cu 0.05 O x -H 2 catalyst exhibited the best performance in CO-SCR, achieving above 90% NO conversion at 162 °C. Various characterization techniques showed that the H 2 treatment effectively reduced some of the CuO and Rh 2 O 3 , creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface, rather than forming difficult-to-decompose nitrates. This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

V 2 O 5 -WO 3 /TiO 2 (VWTi) catalyst has long been utilized in fixed source flue gases to purify harmful NO gas. However, VWTi is classified as a hazardous material because of its harm to human health and environment. To address this issue, a low-cost green Cu-based zeolite catalyst (Cu@13X) with a wide temperature range was synthesized using an in-situ hydrothermal method. This method is intended to control the adsorption capacity of toxic SO 2 by regulating the location of Cu species. UV-Vis DRS and EXAFS analyses revealed that a significant amount of Cu was encapsulated within the 12-membered ring pores of the 13X molecular sieve. SO 2 -TPD and DFT calculations further indicated that Cu@ 13X exhibits reduced SO 2 chemical adsorption capacity. Consequently, this green catalyst demonstrated superior catalytic performance, maintaining superior NO x conversion for over 70 h in the mixture gas containing 250 ppm SO 2 ; while the Cu/13X catalyst lacked NH 3 -SCR catalytic activity under the same conditions. Moreover, Cu@ 13X catalyst also has excellent NH 3 -SCR catalytic performance in low temperature flue gas below 250 °C, which is significantly better than the hazardous VWTi catalyst. Characterization techniques such as NH 3 -TPD, H 2 -TPR, and XPS confirmed that the Cu@ 13X catalyst possesses excellent acidity, robust redox capabilities, and abundant surface defects. In-situ DRIFT spectra further illustrated that the NH 3 -SCR reaction on the catalyst surface adheres to the Eley-Rideal mechanism both before and after the introduction of toxic SO 2. This study offers a fresh perspective on the development of framework-confined NH 3 -SCR catalysts and elucidates the mechanism behind the sulfur resistance of these catalysts. And the green Cu@ 13X catalyst is anticipated to serve as an effective alternative to the hazardous VWTi catalyst. [Display omitted] • Novel Cu@ 13X zeolite-based catalyst was synthesized by in-situ hydrothermal method. • Cu@ 13X can be used as an eco-friendly substitute for hazardous V-based SCR catalyst • Cu@ 13X catalyst has splendid catalytic activity in NH 3 -SCR atmosphere containing SO 2. • Cu species are confined by 13X framework, thereby weakening the chemisorption of SO 2. • Whether SO 2 is present or not, the SCR reaction on Cu@ 13X follows the E-R mechanism. [ABSTRACT FROM AUTHOR]

Oxygen atom migration within solid oxides exerts a profound affects material properties, yet a rigorous conceptual framework for quantifying dynamic migration has been absent. To bridge this gap, we have developed a dynamic oxygen migration-release model, employing the differential element method with comprehensive mathematical proof. This novel model elucidates the exponential decay in the oxygen release rate of metal oxides as a function of the liberated oxygen quantity. We refined the model to discern between the migration of interior (bulk) oxygen and the reactions of oxygen at the surface, providing experimental validation for the energy barriers associated with each migration process. Taking CeO 2 as a case study, our model predicted and corroborated the energy barrier for oxygen release under various temperatures and morphologies, aligning with Density Functional Theory (DFT) analysis. Furthermore, the model's versatility is evidenced by its applicability to a wide range of metal oxides, including ceria-zirconia solid solutions, manganese oxide, and iron oxide, suggesting a broad potential for universal application. The unveiled dynamics of oxygen migration and release provide a theoretical foundation for refining the design of functional metal oxides and lay the groundwork for a more precise assessment of their oxygen reactivity. [Display omitted] • A novel method has been designed to measure the Oxygen Storage/Release Capacity (OSC) of Ce-materials. • Based on the dynamic model, the oxygen behavior of Ce-materials has been explained. • The dynamic oxygen behavior of CeO 2 with different morphologies have been analyzed based on the method and model. [ABSTRACT FROM AUTHOR]

[Display omitted] Pt nanoclusters (Pt C) on the surface of ceria-zirconia solid solutions exhibit superior low-temperature CO oxidation activity compared to Pt single atoms (Pt 1). However, the redispersion behavior of the Pt C to Pt 1 lowers the efficiency of CO Oxidation. In this work, the stable surface hydroxyl groups were constructed by high-temperature hydrothermal aging treatment. Specifically, the Pt 1 catalyst (Pt/CZOe-SA) prepared by atom trapping was subjected to high-temperature hydrothermal treatment to obtain the stable Pt C catalyst (Pt/CZOe-HT) with in-situ formed Pt C. The experimental results showed that Pt C with 2–3 nm size could achieve excellent low-temperature activity and thermal stability. In addition, the ab initio molecular dynamics and density functional theory calculations revealed the specific evolution process of dynamic dispersion for Pt C with or without hydroxyl groups from the femtosecond scale, suggesting that the hydroxyl groups limited the dispersion of Pt C in the form of "energy fence". The hydrothermal treatment not only introduced high-temperature stable hydroxyl groups to improve the stability of the in-situ formed Pt C , but also optimized the ratio of Pt 1 and Pt C , and then enhanced the low-temperature activity by the synergistic effect between Pt 1 and Pt C. The present work can provide theoretical guidance for developing high-performance and high-stability Pt-based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic efficiency of Rh-Mn bimetallic catalysts was investigated for the CO-SCR reaction. • The synthesis method using citric acid and ethylene glycol promotes dispersion of Rh. • The synergistic interaction between Rh and Mn enhances the adsorption and dissociation of NO. • The catalytic mechanism was elucidated through kinetic experiments and in-situ DRIFTs. The selective catalytic reduction of NO by CO (CO-SCR) presents an economical and promising approach to mitigate emissions of NO x and CO from motor vehicles. A bimetallic Rh-Mn supported catalyst Rh-Mn/CoAlO was synthesized through the reduction of citric acid and ethylene glycol, and subsequently employed in the CO-SCR reaction. Tests assessing its catalytic performance revealed that the Rh-Mn/CoAlO catalyst displayed superior CO-SCR activity, maintaining high efficiency (≥90 % at 230 °C) and stability while simultaneously reducing the usage of noble metals. Various characterization techniques, including H 2 -TPR, NO-TPD, CO-pulse, and XPS, indicated that the Rh-Mn/CoAlO catalyst possessed enhanced dispersion of noble metals. This increased dispersion ensured optimal contact between Rh and Mn, as well as the support, fostering a synergistic interaction that facilitated electron transfer. Consequently, the catalyst's adsorption and activation capabilities for NO were significantly improved. In situ DRIFTs studies further elucidated that the catalyst primarily followed the E-R mechanism, wherein NO is adsorbed onto the catalyst surface, and subsequently, the N and O atoms generated from pyrolysis react with CO in the gas phase. The findings of this study are anticipated to offer an effective strategy for designing catalysts with exceptional low-temperature activity and high dispersibility for the reduction of NO using CO. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ignition effect caused by atomic-layer Pt clusters was systematically studied. • The synergistic effect between exposed Pt atoms is remarkable: Gathering is a fire! • The E a of atomic-layer Pt clusters on TiO 2 much lower than that of single atom Pt. • The Pt/a-TiO 2 -AL catalyst could achieve more than 90 % of propane at 230 °C. • DFT calculation show that Pt/a-TiO 2 -AL had lower oxygen vacancy formation energy. Developing highly active catalysts for hydrocarbon combustion at low temperatures is paramount but yet challenging. The crystal form of carrier and the dispersion degree of active species have great influence on propane combustion catalysts, but its internal mechanism is still unclear. In this study, the amorphous atomic-layer Pt clusters (AL) and Pt single atoms (SA) on TiO 2 with various crystal phases were prepared and used as propane combustion catalysts, where the as-synthesized Pt/a-TiO 2 catalyst with atomic-layer Pt clusters exhibited better catalytic performance. The Pt/a-TiO 2 -AL could achieve a 90 % propane conversion (T 90) at 230 °C, with the highest reaction rate (39.57 × 10−7 mol g−1 s−1) and TOF value (7.72 × 10−2 s−1) at 240 °C. Kinetic studies showed that oxygen had a lower inhibitory effect on Pt/a-TiO 2 -AL compared to that on the Pt/p-TiO 2 -AL and Pt/r-TiO 2 -AL catalysts; simultaneously, the Pt/a-TiO 2 -AL catalyst presented lower apparent activation energy compared with Pt/a-TiO 2 -SA. DFT results showed that atomic-layer Pt clusters on TiO 2 had the lower formation energy of oxygen vacancy than Pt single atoms due to the synergistic effect between adjacent exposed Pt atoms in the fully exposed atomic-layer Pt clusters, which had a higher activation capacity for oxygen and thus accelerated propane combustion through the ignition effect (rapid activation of oxygen and rapid combustion of propane). Our primary results provide a promising approach for the creation of high-efficiency Pt-based catalysts, specifically tailored for the catalytic combustion of volatile organic compounds (VOCs). [ABSTRACT FROM AUTHOR]

A new application of rare earth pyrophosphates in vapor phase Beckmann rearrangement of cyclohexanone oxime was investigated. The rare earth phosphates were characterized by means of XRD, FT-IR, NH3-TPD and water contact angle measurement. It was found that the weak surface acidity and appropriate surface hydrophobicity should be two key factors in the excellent performance of these catalysts. [ABSTRACT FROM AUTHOR]

Abstract: A series of silica-supported 12-silicotungstic acid catalysts (H4SiW12O40, abbreviated as HSiW), modified with various loadings of Teflon (HSiW/SiO2-Teflon), were prepared by an impregnation method. The surface properties of the catalysts were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), BET, infrared (IR) spectroscopy, NH3-TPD and the Drop Shape Analysis (DSA). SEM results combined with energy-dispersive X-ray (EDX) measurements of HSiW/SiO2-Teflon revealed that F-compound (Teflon) is effectively coated on the catalyst surface. The contact angles for water and oil of 50wt% HSiW/SiO2 and HSiW/SiO2-Teflon indicate that HSiW/SiO2-Teflon catalyst enhances not only the surface hydrophobicity but also the surface lipophobicity by means of the addition of Teflon. Silica-supported 12-silicotungstic acid modified with Teflon exhibits higher selectivity and longer lifetime than that of silica-supported 12-silicotungstic acid in isobutene oligomerization. Thus, surface-appropriate lipophobicity of catalysts may be effective for decreasing the interaction between coke precursors and the catalyst surface and for removing deposited coke more easily. [Copyright &y& Elsevier]

Abstract: Oxidation of alcohols (including C2–C6 alkyl alcohols, cyclohexanol, benzyl alcohol, 1-octanol and allyl alcohol) to corresponding aldehydes or ketones has been performed over silver catalyst; the silver catalyst is highly active and selective to the reaction. The mechanism of oxidations of alcohols is inclined to oxidative dehydrogenation at low temperature region (<550K). The facets of silver are ideal versatile facets to activate molecular oxygen and generate oxidative, strong basic oxygen species (O δ−), and weak acidic sites (Ag δ+) which can stabilize the organic intermediates, quickly. The facets of silver containing oxygen integrate several active catalytic sites existing in liquid-phase catalytic oxidation of alcohols and make catalytic reaction more effective. [Copyright &y& Elsevier]

[Display omitted] • Engineering of surface defects significantly enhances the photothermal catalyticpropane combustion activity. • The impact of oxygen vacancies on photothermal effect boosts the surface temperature. • Kinetic analysis, in-situ spectroscopy studies, and theoretical simulations elucidate the catalytic mechanism. Photothermal synergistic catalysis for volatile organic compounds has been widely exploited due to its low energy consumption and high-efficiency advantages. However, little is known about how the defect concentration affects the photothermal catalytic performance. Herein, the regulated surface oxygen defects of Pt/WO 3-x via calcined under various atmospheres were synthesized, showing an excellent photothermal catalytic propane combustion over the Pt/WO 3-x with high oxygen vacancies concentration under light without any external heat source. The experiments and theory simulation unveiled a new photothermal reaction mechanism in which surface defects are conducive to broadening the adsorption light and trapping the photogenerated electrons to boost the activation of O 2. This work bodes well for opto-surface defects engineering strategy in advancing and implementing a "solar remove VOCs" process. [ABSTRACT FROM AUTHOR]

Abstract: Polyaniline was used as a nonmetal catalyst in the oxidative dehydrogenation of ethylbenzene and yield of 22.9% at 573K and ∼40% at 673K were obtained, respectively. An indirect oxidative dehydrogenation mechanism was proposed based on the results of pulse reactions. [Copyright &y& Elsevier]

Pt–Ni nanoframes (Pt–Ni NFs) exhibit outstanding catalytic properties for several reactions owing to the large numbers of exposed surface active sites, but its stability and selectivity need to be improved. Herein, an in situ method for construction of a core–shell structured Pt‐Ni NF@Ni‐MOF‐74 is reported using Pt–Ni rhombic dodecahedral as self‐sacrificial template. The obtained sample exhibits not only 100 % conversion for the selective hydrogenation of p‐nitrostyrene to p‐aminostyrene conducted at room temperature, but also good selectivity (92 %) and high stability (no activity loss after fifteen runs) during the reaction. This is attributed to the Ni‐MOF‐74 shell in situ formed in the preparation process, which can stabilize the evolved Pt–Ni NF and donate electrons to the Pt metals that facilitate the preferential adsorption of electrophilic NO2 group. This study opens up new vistas for the design of highly active, selective, and stable noble‐metal‐containing materials for selective hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Three steps are needed to improve the steam-resistance and SO2-resistance of a catalyst for the selective catalytic reduction of NOx through NH3 at low temperature: the first is to introduce a protective layer to reduce the direct contact between SO3 and the catalyst. Then, there is delayed oxidation, which fundamentally reduces the oxidation of SO2 to SO3. If the catalyst is used at a relatively high temperature, it will inevitably produce SO3. The third step is to add a strong acid site in addition to reducing the acidity of the catalyst, which first absorbs NH3 and then absorbs SO3, to seize NH4HSO4, so that it does not cover the active site. GO was used to curl and wrap around the outside of MnO2 nanowires as a protective layer. TiO2 was selectively deposited on oxygen-containing functional groups on GO, which delayed the oxidation ability of the catalyst. ITQ2 molecular sieves acted as strong acid sites to absorb NH4HSO4. The curling behavior of GO outside MnO2 nanowires, the deposition location of TiO2 and the distribution of ITQ2 were explained by morphology and elemental analysis. In the range of 150 °C to 280 °C, the MnO2–GO-scroll–TiO2–ITQ2 catalyst conversion of NO to N2 was more than 85%. Combined with H2-TPR and activity testing, the source of the wide SO2-tolerance temperature range of the catalyst was described in detail. [ABSTRACT FROM AUTHOR]

• A Pt/ceria-zirconia catalyst was prepared by a novel ammonium carbonate etching method. • H 2 O molecules were adsorbed by the catalyst and dissociated into terminal Ce-OH bonds. • The 18O isotope labeling experiments indicated that H 2 O participated in the reaction. • The harmonic oscillator model proved the formation of C18O-Pt2+ during the reaction. CO oxidation reaction has important industrial significance in controlling automotive exhaust emissions, however, the effect of steam on the activity of ceria-zirconia solid solutions supported catalyst is still unclear. In this study, ceria-zirconia solid solutions were prepared by the traditional co-precipitation method (CZO) and the novel ammonium carbonate etching method (CZOe). After loading 1 wt% Pt, the synthesized Pt/CZOe and Pt/CZO catalysts were characterized comprehensively by XRD, HAADF-STEM, XPS, DRIFTS, and Raman spectroscopy, the results suggested that the Pt species were uniformly dispersed as Pt2+ single sites. Both Pt/CZOe and Pt/CZO catalysts could be activated under wet conditions and showed improved CO oxidation activity compared to dry conditions, especially the CO complete conversion temperature (T 100) of Pt/CZOe decreased by 100 °C. Furthermore, the enhancement mechanism of steam on the catalysts has been deeply studied using in-situ CO DRIFTS spectra analysis and 18O isotope labeling experiments, which indicated that H 2 O molecules were adsorbed and dissociated on the surface of the catalysts, forming terminal Ce-OH bonds that facilitated the reaction rate. The Pt/CZOe catalyst showed a remarkable enhancement of low-temperature CO oxidation activity under wet conditions compared to the Pt/CZO catalyst due to the outstanding porosity which facilitates the adsorption of H 2 O molecules. In the H 2 18O-involved experiments, the formation of C18O 2 and C18O16O and the appearance of the C18O-Pt2+ band demonstrated that H 2 O molecules participated in the reaction directly as reactants, the C O bond of CO molecules adsorbed on Pt could be broken and replaced by hydroxyl oxygen of adjacent Ce-OH. The present work revealed the enhancement effect and mechanism of steam on the CO oxidation performance of ceria-zirconia solid solutions supported catalyst, and the research methods and results in this work have important reference significance for the activation research of other catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The unique design strategy of completely sulfur-resistant catalyst was put forward. • β zeolite functioned as a sub-nano reactor to promote the oxidation of NO to NO 2. • Series catalytic reaction of NO oxidation and fast SCR occurred on the β zeolite. • The NO oxidation process under different conditions was analyzed and visualized. • Metal-free β zeolite without redox sites achieved complete immunity to SO 2 in SCR. Sulfur oxides present in flue gas can deactivate metal oxide catalysts or metal cation exchange zeolite catalysts used in NH 3 -SCR, as the deposition of (NH 4) 2 SO 4 /NH 4 HSO 4 and metal sulfate can obstruct and damage active sites, respectively. The physical poisoning of the (NH 4) 2 SO 4 /NH 4 HSO 4 deposition can be prevented by selecting an appropriate reaction temperature range (reversible), while chemical poisoning caused by the sulfation of active sites is challenging to avoid and can permanently deactivate the catalyst (irreversible). This research addresses the issue of irreversible catalyst deactivation resulting from sulfur poisoning by employing metal-free β zeolite without redox sites, which effectively prevents redox site sulfation at its source and shields the catalyst from physical poisoning by operating at moderate to high temperatures. This metal-free β zeolite with an appropriate pore structure exhibited exceptional deNO x activity, N 2 selectivity, stability, and sulfur resistance at 300 °C. The NO oxidation experiment and DFT analysis demonstrated that the specific pore structure of β zeolite functioned as a sub-nano reactor, facilitating the oxidation of NO to NO 2 , thereby triggering the subsequent series catalytic reaction of "fast" SCR. Even in an atmosphere with a high concentration of 300 ppm SO 2 , the β zeolite catalyst maintained over 80 % NO x conversion after 130 h. The slight reduction in activity was attributable to the inhibitory influence of SO 2 on the collision reaction between NO and O 2 ; however, SO 2 did not have any poisonous impact on the catalyst. The unique design strategy found in present work provides valuable insights for the sulfur resistance of metal-free zeolites used in NH 3 -SCR process, and provides a new idea for the design of completely sulfur-resistant catalysts. [ABSTRACT FROM AUTHOR]

• The proportion of Ostwald ripening migration of single atoms of Pt and Rh in the lean/rich oxygen alternating shift atmosphere containing CO (that is, automobile exhaust atmosphere) is close to 100 %. • Dual stable Ce-based oxides could capture and stabilize precious metals migrated due to Ostwald ripening. • The performance breakthrough was achieved and a new mechanism for improving the thermal stability of highly dispersed metal active centers under real reaction conditions was revealed. Precious metal catalysts have been widely used to catalyze various reactions, particularly three-way catalysts for automobile exhaust purification. Pt, Pd, and Rh, which are dispersed on Ce-based oxides that store and release oxygen, serve as the active center of a catalyst. However, methods to construct multifunctional three-way catalysts to maximize their efficiency and stabilize them are lacking. In this study, Ce-based oxides with a double-stable mode were synthesized to capture and stabilize the precious metals Pt and Rh migrated by Ostwald ripening (OR), and a multicomponent three-way catalyst was accurately synthesized, which showed good catalytic activity and thermal stability. The origin of Ce-based oxides with a dual-stable mode was studied by TEM, XRD, oxygen storage/release capacity and rate test, and XPS. AC-STEM, EXAFS, in situ diffuse reflectance Fourier transform infrared, and H 2 temperature-programmed reduction studied the OR migration of precious metals and the composition change after aging. Results showed that in the lean/rich oxygen alternating shift atmosphere containing CO, the proportion of OR migration of Pt and Rh precious metals whose initial state is single atoms can reach 100 %. This discovery provides a basic understanding of the sintering mechanism of precious metals, which is of great importance for the development and industrial application of three-way catalysts. Figure caption: In the lean/rich oxygen alternating shift atmosphere containing CO (automobile exhaust atmosphere), a new method for preparing super stable Pt-Rh alloy three-way catalyst from Pt and Rh single atoms was established with the help of Ostwald ripening migration mechanism. The performance breakthrough was achieved and a new mechanism for improving the thermal stability of highly dispersed metal active centers under real reaction conditions was revealed. [Display omitted] [ABSTRACT FROM AUTHOR]

Catalytic vapor-phase dehydration of glycerol is an energy-efficient and environmentally friendly route for producing acrolein, a valuable organic chemical intermediate. However, anti-coking is one of the key problems due to the excessively acid catalytic sites and sluggish mass transfer, restricting the industrial application of this reaction. Herein, potassium element modified BPO 4 monolithic foams with the hierarchically porous structure were synthesized by adding potassium element in the gel precursor of BPO 4. The catalyst introducing 3% K exhibited the best acrolein selectivity of 81.0% with nearly complete glycerol conversion. In a 10-hour run of the reaction at 320 °C, the selectivity of acrolein could remain at 75.9% with 94.5% glycerol conversion, indicating the superior stability. The excellent activity and stability for 3% K-BPO 4 is mainly attributed to the synergetic effect between hierarchical structure providing favorable mass transfer and appropriate acid catalytic sites inhibiting over dehydration reaction. They not only boost activity but also reduce coking, providing a unique approach for the design of solid acid catalyst. [Display omitted] • Hierarchical pore of K-modified BPO 4 catalyst is conducive to mass transfer. • The catalyst had adjustable acidity and encouraging resistance to carbon deposition. • The catalyst exhibited good conversion, selectivity, and stability in glycerol dehydration. [ABSTRACT FROM AUTHOR]

Sintering and sulfur poisoning are the causes of the deactivation of most catalysts. Herein, the Pd clusters were encapsulated into the all-silica zeolite by one-step synthesis to obtain a core-shell structure (denoted as Pd@S-1) for catalytic combustion of methane with good catalytic activity and high stability. Under the harsh conditions such as 800 °C aging for 10 h, 10% water vapor aging for 100 h and 100 ppm SO 2 poisoning for 15 h, the Pd particles are prevented from migration and growth due to the confinement of the S-1 shell layer. As comparison, Pd/S-1 and Pd 0.8 Ni 0.2 /S-1 sample have different degrees of sintering, resulting in partial deactivation. For Pd 0.8 Ni 0.2 @S-1 sample, the introduction of Ni not only enhances the catalytic activity, but also improves the thermal stability. However, the moisture and sulfur resistance of Pd 0.8 Ni 0.2 @S-1 catalyst is much lower than that of Pd@S-1 catalyst. A series of characterizations show that the S-1 shell has a shielding effect for SO 2. We proposed that the formation of large-sized PdSO 4 clusters is prevented due to the confinement effect of S-1 micropore, resulting in SO 2 easily desorbed on Pd@S-1 surface, which significantly lowers the temperature of Pd@S-1 catalyst regeneration. Unlabelled Image • The confinement effect of the S-1 shell prevents the growth of Pd nanoparticles. • The Pd 0.8 Ni 0.2 @S-1 catalyst does not undergo severe sintering at 900 °C for 5 h with the T 90 = 425 °C. • Even under 450 °C, 10% water vapor for 100 h, the Pd particle size on the Pd@S-1 remains unchanged. • The sulfur-poisoned Pd@S-1 catalyst can recover its catalytic activity under lean-burn conditions. [ABSTRACT FROM AUTHOR]

A series of nanosized Cu/SAPO‐34 catalysts with different silicon contents were successfully synthesized by in situ hydrothermal method by using tetraethylammonium hydroxide and copper‐tetraethylenepentamine as co‐templates. The in situ prepared nanosized Cu/SAPO‐34 catalysts possess strong Brønsted acidity and well‐dispersed Cu species, showing enhanced performance for selective catalytic reduction of NOx with NH3 compared with micronsized and nanosized counterparts prepared by post impregnation method. Significantly, Cu/SAPO‐34 nanocatalysts prepared by in situ method maintain the catalytic activity after the hydrothermal aging treatment, suggesting their excellent hydrothermal stability. This work will provide some guidance for the design of highly efficient catalysts for NH3−SCR reactions. [ABSTRACT FROM AUTHOR]

Catalytic combustion has become one of the most economical, feasible and effective tools for the abatement of VOCs. However, it is difficult to prepare supported Pt catalysts possessing both excellent catalytic activity and stability by traditional preparation methods, such as incipient‐wetness impregnation method and nanoparticle loading method. In this work, we prepared Pt/Co3O4 catalyst with high catalytic activity and stability for the catalytic combustion of toluene by galvanic displacement method. As comparing, additional reference samples were prepared using incipient‐wetness impregnation method and nanoparticle loading method, respectively. All of the samples were characterized by XRD, TEM, H2‐TPR, O2‐TPD and XPS techniques. The catalyst prepared by galvanic displacement method exhibited the best catalytic activity with the temperature of 90 % toluene conversion about 150 °C (T90 = 150 °C) and outstanding stability reflected in a continuous 100 h on‐stream toluene combustion lifetime experiment without catalytic activity decline at the GHSV = 60 000 mL g–1 h–1 compared to which prepared by traditional methods. These results are attributed to the excellent oxygen mobility, the high surface chemisorbed oxygen species concentration and the strong interaction between Pt and support Co3O4. Therefore, our work provided a universal strategy for designing high‐efficiency and stable catalyst for the abatement of VOCs at low temperature. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. • The MnO x /CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. • The process of NO oxidation to NO 2 over the catalyst plays a key role during the NH 3 -SCR process. • Monodentate nitrates were the major active species for the NO removal. • The reaction process of the MnO x /CePO 4 catalyst was majorly conducted via the Langmuir–Hinshelwood mechanism. Abstract The MO x (M = Cu, Mn, Co)/CePO 4 support was firstly prepared via the hydrothermal and impregnated method. Selective catalytic reduction of NO with NH 3 (NH 3 -SCR) results showed that the MnO x modifications greatly improved the SCR activities at low temperatures. The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. In-situ DRIFTS results suggest that the SCR reaction is majorly conducted between the absorbed monodentate nitrate and NH 3 species (i.e., the Langmuir–Hinshelwood mechanism). MOx (M = Cu, Mn, Co) exists in the formation of nano-size particles obtained by SEM and TEM directly. These nano-size particles can provide active surface adsorbed oxygen and thus improve the NO oxidation ability as indicated by the O 2 -TPD and NO oxidation tests. The process of NO oxidation to NO 2 plays a key role to produce the absorbed monodentate nitrate as indicated by the In-situ DRIFTS. The support CePO 4 acts as the acid sites to form highly active NH 4 + species. The synergic effect between the MnO x and CePO 4 contributed to the high SCR activity over the MnO x /CePO 4 catalyst. Additionally, the MOx/CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. Consequently, the MnO x /CePO 4 catalyst becomes the potential catalyst for the practical process. [ABSTRACT FROM AUTHOR]

It is essential to develop the catalyst for NH 3 -SCR with excellent performance at ultra-low temperature (≤150 °C), and resource recycling is another important part of environmental protection. Based on the principle of environmental friendliness, the LiMn 2 O 4 , one of the waste battery cathode materials, was successfully modified into a novel high-value catalyst for ultra-low temperature NH 3 -SCR through hydrogen ion exchange and two-dimensional vanadic oxide modification. The optimized LiMn 2 O 4 -0.5V-10H catalyst performed the best balance of NO x conversion and N 2 selectivity, with activity reaching 96 % at 150 °C and N 2 selectivity exceeding 70 % at ultra-low temperature. Due to the unique three-dimensional network structural characteristics of LiMn 2 O 4 spinel, hydrogen exchange could exchange Li+ from the lattice and increase surface acidity; and a small amount of two-dimensional vanadic oxide loading could appropriately regulate redox ability and increase acidic sites. The in-situ DRIFTS results still showed that the L-H and E-R mechanisms coexisted during the reaction. Moreover, combining first-principles calculations and in-situ DRIFTS, the dual modification of H and V could enhance the adsorption of NH 3 on the surface of LiMn 2 O 4 but weaken the adsorption of NO, and promote the decomposition of nitrites while inhibit the formation of surface nitrate species, which was the core reason for the improvement of N 2 selectivity. The modification mode in this work was simple and inexpensive, which provided a new idea for the high-value utilization of waste batteries and the design of NO x purification catalyst at ultra-low temperature. [Display omitted] • The waste battery was successfully transformed into a novel high-value SCR catalyst. • Replacing Li+ with H+ could significantly improve the acidity and redox ability. • Loaded two-dimensional V 2 O 5 cluster could appropriately regulate the redox capacity. • Dual modification of H and V could inhibit the formation of surface nitrate. • The optimized Li x Mn 2 O 4 had efficient NH 3 -SCR performance at ultra-low temperature. [ABSTRACT FROM AUTHOR]

We reported an updated sol‐gel method for the preparation of perovskite oxide using ethylene glycol and alcohol mixture as complexant. Relative to that prepared by sol‐gel method using citric acid as complexant, the sample prepared by this updated method showed porous structure, higher surface area, more oxygen vacancies and stronger reducibility, due to a two‐step combustion process. By comparing the phase transformation temperature of perovskite oxides using different transition metals, it was inferred that the electron distribution in the 3d orbit is a crucial factor influencing the formation of perovskite structure. The easier the electrons to be excited, the easier the perovskite structure to be formed. Catalytic results showed that the sample (e. g. LaCoO3‐EM) prepared by the updated method is more active for CO oxidation than that prepared by citric acid method, with full CO conversion obtained at 135 °C and no activity loss is observable either by long‐term (30 h) or by cycling (3 times) stability tests. Effect of the chain length of alcohols on the properties of LaCoO3 was also studied. Porous perovskite oxides were prepared by an updated sol‐gel method and showed good catalytic performances for CO oxidation reaction. [ABSTRACT FROM AUTHOR]

• The Pt/CeO 2 nanorods catalyst was modified with three different acids for propane catalytic combustion. • Mo-modified Pt/CeO 2 catalyst converted more than 90% of propane at 300 ℃. • Pt/CeO 2 -Mo catalyst had a stronger acidic and redox capacity. • The order of reaction of Pt/CeO 2 -Mo catalyst to oxygen is −0.4, which is benefit to the adsorption of propane. • MvK mechanism the reaction followed on Pt/CeO 2 -Mo catalyst was confirmed by in situ DRIFTs. Catalytic combustion is the most commonly used reaction to purify VOCs. The activation and dissociation of the C H bond over the catalyst becomes a key factor in controlling the rate of the reaction. To identify the factors promoting C H bond decomposition and the roles played by the acidity of the catalyst in propane catalytic combustion, molybdic acid, phosphoric acid, and sulfuric acid were used to acidify CeO 2 nanorods, and Pt was then loaded onto the nanorods. The Mo acid modified Pt/CeO 2 catalyst purified more than 90% of propane at a high space velocity of 150,000 mL/(g·h) and 300 °C, which is a significant improvement over the Pt/CeO 2 catalyst. XRD patterns and TEM images showed that the crystal structure and morphology of CeO 2 were not damaged by acid modification. XPS, in situ CO-DRIFTs, NH 3 -TPD, H 2 -TPR and other characterization methods were used on Mo acid modified catalysts to explore the reasons for the improved catalytic performance. The results showed that Pt2+ and Pt4+ coexist on 1% Pt/CeO 2 -18Mo catalyst, and there are more acidic sites, redox sites and adsorbed oxygen. The reaction order test showed the reaction order of molybdic acid modified catalyst to oxygen is -0.4, which is higher than other catalysts, meaning that oxygen is difficult to inhibit the reaction on the catalyst surface. Finally, in situ DRIFTs proved that 1% Pt/CeO 2 -18Mo catalyst had strong propane adsorption and activation capacity. This catalyst provides new insight into how VOCs can be eliminated more efficiently, green and economically. [Display omitted] [ABSTRACT FROM AUTHOR]

• Ruthenium nanoparticles supported on gallium-modified molecular sieve applied for generating hydrogen from its hydride ammonia via its photothermal decomposition. • The thermal effect of light enhanced the efficiency of the reaction much more than heating. • Natural light in the photothermal synergistic catalysis is sustainable and economical. Because the high electron cloud density around Ru is favorable for ammonia decomposition, gallium addition to it resulted in an alkaline molecular sieve carrier with a large specific surface area. It was revealed that GaOH not only elevated the electron cloud density near the active center of Ru but also encouraged N H bond breaking and hydrogen atoms' binding on the catalyst surface. Furthermore, the molecular sieve's regular pore structure strongly inhibited the growth of Ru particles within it, resulting in a high degree of mono-dispersion of Ru nanoparticles and a reduction in the average particle size of the Ru active center to < 3 nm. For TOF >1, the above two factors combined to decrease the ammonia decomposition temperature to < 450 °C. Furthermore, under photothermal synergistic catalysis, the hydrogen production rate via ammonia decomposition was further elevated, and the reaction temperature was further decreased to < 380 °C with TOF > 1. In situ UV photoelectron spectroscopy clarified that the hydrogen atom concentration on Ru increased during photothermal catalysis. According to the FT-IR analysis of the surface intermediate of NH/NH 2 formed by ammonia decomposition, photothermal synergistic catalysis can weaken the N H bond compared with pure heating, making it easier for H atoms to combine and form H 2. The test results of the correlation between activation energy, reaction rate, and ammonia partial pressure show that, when compared to pure thermal catalysis, photothermal catalysis does not substantially alter the reaction path. The primary reason behind the increased hydrogen production rate of ammonia decomposition by photothermal catalysis was the thermal effect of the light source. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Introduction of WO 3 promoted N 2 selectivity and broadened temperature window. • Novel assembly strategy " acidity u & redox d " balanced activity and N 2 selectivity. • Doping WO 3 changed the reaction mechanism that promoted NH 3 /inhibited NO adsorption. • Doping rare earth elements improved redox ability and low temperature activity. • The modified acid zeolite-like montmorillonite is an efficient SCR catalyst support. It is still a challenge for de-NO x catalysts to have high activity and N 2 selectivity in a wide low-temperature operating temperature window. In this work, we used layered zeolite-like montmorillonite as the support and then obtained a composite catalyst with satisfactory NO x conversion and excellent N 2 selectivity in the temperature range of 100–300 °C with the method of pillaring modification, active component doping, and catalyst assembly. It has been proved that doping rare earth elements can improve the redox ability of the catalyst, and WO 3 modification can enhance the acidity of the catalyst. The redox ability and the surface acidity of the catalyst system were balanced by assembling the WO 3 -modified catalyst and the WO 3 -unmodified catalyst. Besides, we found the composite Pr 1 Mn 9 /Fe 7 Ti 3 -W u -mmt catalyst had the best catalytic activity and N 2 selectivity only when the reaction gas first passed through the catalyst modified by WO 3 , in which the WO 3 -modified catalyst acted as the role of nitrous oxide filter. What's more, according to the results of in situ DRIFTS, it can be indicated that the montmorillonite-supported catalysts in this work followed the L-H mechanism and E-R mechanism; while the E-R mechanism was dominant when the catalyst was modified by WO 3. The results in present work indicate that the novel strategy of assembling catalysts is practicable to obtain an efficient de-NO x catalyst with a wide low-temperature operating temperature window, high NO x conversion, and high N 2 selectivity. Furthermore, the novel assembly strategy of tandem catalysis with stronger acidity sites and redox sites in turn " acidity u & redox d " can be extended to other SCR catalytic systems. [ABSTRACT FROM AUTHOR]

A series of Ag-modified Ni catalysts was prepared, and the role of bimetallic effects on the selective cleavage of C−O and C−C bonds was investigated in glycerol hydrogenolysis, a model reaction for the utilization of biomass-derived polyols. Compared to Raney Ni, the optimal Raney Ni6Ag catalyst was more active in glycerol conversion and efficient for C−O bond cleavage to afford a higher selectivity toward C3 products (1,2-propanediol and lactic acid; 88 %) at the same ∼70 % conversion of glycerol, especially 1,2-propanediol (73 %). On Ni catalysts, the hydrogenation of adsorbed species was the most likely rate-limiting step in glycerol hydrogenolysis under alkaline conditions. The Ag additive enhanced the hydrogenation ability of Ni catalysts, which should be related to the higher strength of the adsorption of hydrogen and the lower strength of the adsorption of substrates on Ni sites because of the formation of Ni-Ag alloys. A mechanistic interpretation was presented for the excellent catalytic behavior. [ABSTRACT FROM AUTHOR]

Pd@CeO2 core-shell nanostructures with a tunable Pd core size, shape, and nanostructure as well as a tunable CeO2 sheath thickness were obtained by a biomolecule-assisted method. The synthetic process is simple and green, as it involves only the heating of a mixture of Ce(NO3)3, l-arginine, and preformed Pd seeds in water without additives. Importantly, the synthesis is free of thiol groups and halide ions, thus providing a possible solution to the problem of secondary pollution by Pd nanoparticles in the sheath-coating process. The Pd/CeO2 nanostructures can be composited well with γ-Al2O3 to create a heterogeneous catalyst. In subsequent tests of catalytic NO reduction by CO, Pd@CeO2/Al2O3 samples based on Pd cubes (6, 10, and 18 nm), Pd octahedra (6 nm), and Pd cuboctahedra (9 nm) as well as a simply loaded Pd cube (6 nm)-CeO2/Al2O3 sample were used as catalysts to investigate the effects of the Pd core size and shape and the hybrid nanostructure on the catalytic performance. [ABSTRACT FROM AUTHOR]

Pd@CeO2 core-shell nanostructures with a tunable Pd core size, shape, and nanostructure as well as a tunable CeO2 sheath thickness were obtained by a biomolecule-assisted method. The synthetic process is simple and green, as it involves only the heating of a mixture of Ce(NO3)3, l-arginine, and preformed Pd seeds in water without additives. Importantly, the synthesis is free of thiol groups and halide ions, thus providing a possible solution to the problem of secondary pollution by Pd nanoparticles in the sheath-coating process. The Pd/CeO2 nanostructures can be composited well with γ-Al2O3 to create a heterogeneous catalyst. In subsequent tests of catalytic NO reduction by CO, Pd@CeO2/Al2O3 samples based on Pd cubes (6, 10, and 18 nm), Pd octahedra (6 nm), and Pd cuboctahedra (9 nm) as well as a simply loaded Pd cube (6 nm)-CeO2/Al2O3 sample were used as catalysts to investigate the effects of the Pd core size and shape and the hybrid nanostructure on the catalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of Co3O4 samples with micro/nano-structure as high capacity anode materials for Lithium-ion Batteries are synthesized by a facile method. The structure, composition and surface morphology are analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), respectively. The XRD data indicates that the two Co3O4 materials are crystalline, single-phase without any impurity phase; the size of spheres and cubes are estimated to be 2 μm and the nanoparticles are around 100 nm. The cyclic voltammetry and discharge/charge measurements are carried out to detect the electrochemical properties. The results demonstrate that the two Co3O4 electrodes with micro/nano-structure exhibit low initial irreversible capacity and superior cycling performance. The two Co3O4 materials with micro/nano-structure are confirmed to combine the advantages of the micro-materials and nano-materials for LIBs. Moreover, the Co3O4 spheres (s-Co3O4) exhibit more superior cycling performance than that of Co3O4 cubes (c-Co3O4) due to the larger void volume in spheres than that in cubes structure. [Copyright &y& Elsevier]

Abstract: An enzymeless glucose biosensor based on polypyrrole nanofibers-supporting Au nanoparticles (Au/PPyNFs) was investigated in this study. The Au/PPyNFs heterogeneous composite materials were synthesized in-situ via hydrogen bonding interactions for the assembly of polyethyleneimine (PEI) on the surface of polypyrrole nanofibers (PPyNFs). By changing the molar ratio of PPy to HAuCl4, Au/PPyNFs with different Au loadings were obtained. The morphology and composition of Au/PPyNFs were characterized using SEM, TEM, FTIR, XRD and XPS, respectively. The hybrids exhibited a high electrocatalytic activity toward glucose oxidation, which is prerequisite for the catalysts to be applied in amperometric glucose sensors. By using the nonenzymatic glucose sensor based on Au/PPyNFs, 0.2–13mM glucose can be detected with a sensitivity of 1.003μAcm−2 mM−1 and a good linearity (R 2=0.9993) between current density and glucose concentration. The proposed glucose sensor provides a promising strategy to construct fast, sensitive, and anti-interfering amperometric sensors for early diagnosis and prevention of diabetes. [Copyright &y& Elsevier]

Abstract: Au@Pd core–shell nanoparticles (NPs) were synthesized using seed-mediated method, and three samples with different shell structures were obtained by tuning the Au core size. The shape-dependent catalytic activities of Au@Pd core–shell NPs toward ethanol oxidation in alkaline electrolytes were systematically explored. The electrochemical experiments showed that the Au@Pd-2 core–shell NPs (with Au core size of 9.8nm and loose Pd shell) exhibited a distinctly higher activity and poison-resistance for the ethanol oxidation than other core–shell structures. Based on the Au@Pd-2 core–shell NPs and Pd NPs, two amperometric ethanol gas sensors were fabricated. During the sensor tests, the ethanol sensor based on Au@Pd-2 NPs showed good performance for ethanol in the range of 50–600ppm with sensitivity of 178.5nAppm−1 and less than 5% signal loss in 60 days. [Copyright &y& Elsevier]

Abstract: In this work hollow Pd nanospheres were successfully synthesized by using galvanic replacement of facile synthesized Cu2O nanospheres with palladium for the first time. The SEM showed the hollow structure of Pd nanospheres and the XRD analysis proved the successful preparation of Pd. This method is surfactant-free, and well-dispersed hollow Pd nanospheres can be obtained through this route. It was found that the hollow Pd nanospheres showed good electrochemical properties and could be used as catalysts in DEFCs. From cyclic voltammograms, the onset potential of hollow Pd nanospheres shifted negatively by 100mV and the peak current of hollow Pd nanospheres was about two times higher than that of solid Pd nanospheres. [Copyright &y& Elsevier]

Recently, rare earth ternary coordination catalyst represented as Y(CCl3OO)3-Glycerin-ZnEt2 has been used for producing poly(propylene carbonate) (PPC, an alternating copolymer of carbon dioxide and propylene oxide) in industry scale, but its catalytic activity needs further improvement. One reason for the relatively low catalytic activity lied in that only 11.7% of active center was efficient due to possible embedding of active center in the heterogeneous catalyst. In this report, supporting strategy was developed, where Y(CCl3OO)3-Glycerin-ZnEt2 was supported on various inorganic oxides. Two supporting methods were carried out. One way was to mix Y(CCl3OO)3-Glycerin with inorganic oxide first and then ZnEt2 was dropped to form the supported catalyst, and the other was to make Y(CCl3OO)3-Glycerin-ZnEt2 at first and then mixing with inorganic oxides. The former showed decreasing catalytic activity compared with corresponding unsupported rare earth ternary catalyst, while an improvement of 16-36% in catalytic activity was realized in the latter. PPC with an average number molecular weight ( Mn) of over 100 kg/mol and carbonate unit (CU) content of higher than 96% was prepared by both supported catalysts. The catalytic activity of the supported catalyst depended significantly on the supports, which increased in the following order: α-Al2O3 < MgO < ZnO ≈ SiO2 <γ-Al2O3. γ-Al2O3 was the best support for rare earth ternary catalyst, which showed a remarkable 36% increase in catalytic activity, corresponding to the utilization of 17% of active center. Although MgO supported catalyst gave only an 8% increase in catalytic activity, the Mn and CU content of PPC were raised to about 143 kg/mol and 99%, whereas the PPC from common rare earth ternary catalyst was about 108 kg/mol and 97%, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 [ABSTRACT FROM AUTHOR]

Catalytic NO decomposition on LaSrMn1− xNi xO4 +δ (0 ≤ x ≤ 1) is investigated. The activity of NO decomposition increases dramatically after the substitution of Ni for Mn, but decreases when Mn is completely replaced by Ni ( x = 1.0). The optimum value is at x = 0.8. These indicate that the catalytic performance of the samples is contributed by the synergistic effect of Mn and Ni. O2-TPD and H2-TPR experiments are carried out to explain the change of activity. The former indicates that only when oxygen vacancy is created, could the catalyst show enhanced activity for NO decomposition; the latter suggests that the best activity is obtained from catalyst with the most matched redox potentials (in this work, the biggest Δ T and Δ E values). The close relationships between activity and Δ T or Δ E indicate that Δ T and Δ E are important parameters of catalyst for NO decomposition. [ABSTRACT FROM AUTHOR]

Abstract: Liquid phase oxidation of cyclohexane was carried out under mild reaction condition over copper pyrophosphate catalyst in CH3CN using hydrogen peroxide as an oxidant at the temperature between 25 and 80°C. The copper pyrophosphate catalyst was characterized by means of XRD, FT-IR and water contact angle measurement. It was found that appropriate surface hydrophobicity is the key factor for the excellent performance of the catalyst. In addition, a significant improvement for the cyclohexane conversion in the presence of organic acid was observed. [Copyright &y& Elsevier]

Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 °C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd4(P2O7)3 precipitated at pH = 6 and calcined at 500 °C in the catalyst preparation. [ABSTRACT FROM AUTHOR]

Abstract: It is discovered that SBA-15 (santa barbara amorphous) can provide the favorable microenvironments and optimal direct electron-transfer tunnels (DETT) of immobilizing cytochrome c (Cyt c) by the preferred orientation on it. A high-redox potential (254mV vs. Ag/AgCl) was obtained on glassy carbon (GC) electrode modified by immobilizing Cyt c on rod-like SBA-15. With ultraviolet–visible (UV–vis), circular dichroism (CD), FTIR and cyclic voltammetry, it was demonstrated that immobilization made Cyt c exhibits stable and ideal electrochemical characteristics while the biological activity of immobilized Cyt c is retained as usual. The electrochemistry behavior at the modified GC electrode is surface-controlled quasi-reversible process with an enhanced electron-transfer rate constant of 2.20s−1 because of the optimal DETT between Cyt c and SBA-15. It was also found that the modified GC electrode exhibited a predominant electrocatalytic activity for the reduction of hydrogen peroxide, which may open up a possibility for designing and fabricating enzyme electrodes with application potentials in biosensor and biofuel cells. [Copyright &y& Elsevier]

Abstract: Arabinogalactan derivatives conjugated with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) by ethylenediamine (Gd-DTPA-CMAG-A2) or hexylamine (Gd-DTPA-CMAG-A6) have been synthesized and characterized by means of Fourier transform infrared spectra (FTIR), 13C nuclear magnetic resonance (13C NMR), size exclusion chromatography (SEC), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Relaxivity studies showed that arabinogalactan-bound complexes possessed higher relaxation effectiveness compared with the clinically used Gd-DTPA, and the influence of the spacer arm lengths on the T 1 relaxivities was studied. Their stability was investigated by competition study with Ca2+, EDTA, and DTPA. MR imaging of Wistar rats showed remarkable enhancement in rat liver and kidney after i.v. injection of Gd-DTPA-CMAG-A2 (0.079±0.002mmol/kg Gd3+): The mean percentage enhancement of the liver parenchyma and kidney was 38.7±6.4% and 69.4±4.4% at 10–30min. Our preliminary in vivo and in vitro study indicates that the arabinogalactan-bound complexes are potential liver-specific contrast agents for MRI. [Copyright &y& Elsevier]

Abstract: The reaction mechanism of the Beckmann rearrangement over B2O3/γ-Al2O3 and TS-1 in the gas phase has been investigated by isotope labeling approach. The isotopic labeled products were measured by mass spectrometry method. By exchanging oxygen with H2 18O in the rearrangement step, it was found that the exchange reaction between cyclohexanone oxime and H2 18O over B2O3/γ-Al2O3 and TS-1 could only be carried out in some extent. It suggested that the dissociation of nitrilium over solid acids be not completely free as the classical mechanism. A concept of the dissociation degree (α) that is defined as the ratio of the dissociated intermediate nitrilium to the total intermediate nitrilium has been proposed. By fitting the experimental values with the calculation equation of isotopic labeled products, it is obtained that α values for B2O3/γ-Al2O3 and TS-1 are 0.199 and 0.806 at the reaction conditions, respectively. [Copyright &y& Elsevier]

Abstract: Ce and MgO were added simultaneously to La–Sr–Ni–O catalyst and a substantial enhancement of activity for NO decomposition was observed, which may be attributed to the formation of a new highly active site caused by the addition of Ce and MgO. [Copyright &y& Elsevier]

Abstract: NO decomposition reaction was investigated over La2−x Th x CuO4, in which the valence of copper was controlled by Th substitution and was characterized by XPS measurement. A close correlation between the valence of copper and the activity was observed. The activity increased with the decrease of the average oxidation number of copper, and increased with the increase of Cu+ content, suggesting that the transition metal with low valence (Cu+) is active for the reaction in the present cases. [Copyright &y& Elsevier]

Abstract: Fe–Ni–O samples, with Fe/Ni ratio ranging from 2 to 1/3, were synthesized. Samples synthesized with and without citric acid in the precursor were compared and it was found that the addition of citric acid is the necessary condition for FeNi3 formation; it was found that FeNi3 alloys were formed in these samples even when calcined in an air atmosphere. X-ray diffraction and X-ray photoelectron spectroscopy measurements were used to characterize the samples. Because of the existence of FeNi3 alloys, Fe–Ni–O samples showed strong reactivity to NO and NO+O2 but were inert to O2 alone. [Copyright &y& Elsevier]

Abstract: Compound of La2−x Sr x CuO4 (x ≥0.5) with T* phase structure were prepared by conventional citric method. The split peak at 2θ =∼31° in XRD patterns and the broad absorption band at 680cm−1 with a shoulder peak at 620cm−1 in IR spectra suggested the formation of T* phase in La2−x Sr x CuO4 compounds at x ≥0.5. The amount of sample with T* phase structure increased with the increase of Sr content as certified by XRD patterns. Catalytic performance of La2−x Sr x CuO4 for NO decomposition was investigated, and it was found, by correlating the solid-state properties and the activity of NO decomposition, that the presence of T* phase structure enhanced the catalytic activity of La2−x Sr x CuO4 in NO decomposition. [Copyright &y& Elsevier]