We used ab initio molecular dynamics simulations to compare the activation of 2-propanol on the low index Co3O4 (111), (110) and (001) surfaces in dry conditions. The thermal and surface assisted decomposition of a film of 2-propanol to 2-propoxide on the B-termination of each surface was monitored and analyzed. The investigations suggest an activity order of Co3O4 (111) > (110) > (001). On all surfaces, the Co3+ serves as an adsorption sites. On the B-terminated (111) surface, full dissociation of all 2-propanol molecules at the interface is observed, accompanied by a Mars-van Krevelen-type mechanism upon pre-hydroxylation of the surface. The active regions show Co3+–O2-propoxide–Co2+ bridges where the coordinatively unsaturated Co2+ ions also participate in the adsorption and decomposition of 2-propanol. On the (110) surface, 2-propanol dissociation is driven by temperature, which activates the two-fold coordinatively unsaturated surface oxygens. The (001) surface on which almost no dissociation occurs is the least active. No formation of acetone is observed in the simulations conditions on all surfaces.
我们利用 ab initio 分子动力学模拟比较了在干燥条件下 2-丙醇在低指数 Co3O4 (111)、(110) 和 (001) 表面上的活化情况。对每种表面的 B 端上将 2-丙醇分解为 2-丙氧基的薄膜的热分解和表面辅助分解进行了监测和分析。研究表明，Co3O4 的活性顺序为 (111) > (110) > (001)。在所有表面上，Co3+ 都是吸附位点。在 B 端（111）表面，观察到所有 2-丙醇分子在界面上完全解离，并伴随着表面预羟基化后的 Mars-van Krevelen 型机制。活性区域显示出 Co3+-O2-propoxide-Co2+ 桥，其中配位不饱和的 Co2+ 离子也参与了 2-丙醇的吸附和分解。在（110）表面，2-丙醇的解离是由温度驱动的，温度激活了表面的两倍配位不饱和氧原子。几乎不发生解离的 (001) 表面活性最低。在所有表面的模拟条件下都没有观察到丙酮的形成。
{"title":"2-Propanol Activation on the Low Index Co3O4 Surfaces: A Comparative Study Using Molecular Dynamics Simulations","authors":"A. H. Omranpoor, S. Kenmoe","doi":"10.3390/catal14010025","DOIUrl":"https://doi.org/10.3390/catal14010025","url":null,"abstract":"We used ab initio molecular dynamics simulations to compare the activation of 2-propanol on the low index Co3O4 (111), (110) and (001) surfaces in dry conditions. The thermal and surface assisted decomposition of a film of 2-propanol to 2-propoxide on the B-termination of each surface was monitored and analyzed. The investigations suggest an activity order of Co3O4 (111) > (110) > (001). On all surfaces, the Co3+ serves as an adsorption sites. On the B-terminated (111) surface, full dissociation of all 2-propanol molecules at the interface is observed, accompanied by a Mars-van Krevelen-type mechanism upon pre-hydroxylation of the surface. The active regions show Co3+–O2-propoxide–Co2+ bridges where the coordinatively unsaturated Co2+ ions also participate in the adsorption and decomposition of 2-propanol. On the (110) surface, 2-propanol dissociation is driven by temperature, which activates the two-fold coordinatively unsaturated surface oxygens. The (001) surface on which almost no dissociation occurs is the least active. No formation of acetone is observed in the simulations conditions on all surfaces.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"244 8","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139152737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chunlian Luo, Luwei Chen, Abdullah N. Alodhayb, Jianhua Wu, Mingwu Tan, Yanling Yang
The development of catalysts for low-temperature methane combustion is crucial in addressing the greenhouse effect. An effective industrial catalyst strategy involves optimizing noble metal utilization and boosting metal–metal interaction. Here, the PdNi-H catalyst was synthesized using the self-assembly method, achieving the high dispersion and close proximity of Pd and Ni atoms compared to the counterparts prepared by the impregnation method, as confirmed by EDS mapping. The XRD and TEM results revealed Pd2+ and Ni2+ doping within the CeO2 lattice, causing distortions and forming Pd-O-Ce or Ni-O-Ce structures. These structures promoted oxygen vacancy formation in CeO2, and this was further confirmed by the Raman and XPS results. Consequently, the PdNi-H catalyst demonstrated an excellent redox ability and catalytic activity, achieving lower ignition and complete methane burning temperatures at 282 and 387 °C, respectively. The highly dispersed PdNi species played a pivotal role in activating methane for enhanced redox ability. Additionally, the narrow size distribution range contributed to more vacancies on the surface of CeO2, as confirmed by the XPS results, thereby facilitating the activation of gas phase oxygen to form oxygen species (O2−). This collaborative catalytic approach presents a promising strategy for developing efficient and stable methane combustion catalysts at low temperatures.
{"title":"Uniformly Dispersed Nano Pd-Ni Oxide Supported on Polyporous CeO2 and Its Application in Methane Conversion of Tail Gas from Dual-Fuel Engine","authors":"Chunlian Luo, Luwei Chen, Abdullah N. Alodhayb, Jianhua Wu, Mingwu Tan, Yanling Yang","doi":"10.3390/catal14010024","DOIUrl":"https://doi.org/10.3390/catal14010024","url":null,"abstract":"The development of catalysts for low-temperature methane combustion is crucial in addressing the greenhouse effect. An effective industrial catalyst strategy involves optimizing noble metal utilization and boosting metal–metal interaction. Here, the PdNi-H catalyst was synthesized using the self-assembly method, achieving the high dispersion and close proximity of Pd and Ni atoms compared to the counterparts prepared by the impregnation method, as confirmed by EDS mapping. The XRD and TEM results revealed Pd2+ and Ni2+ doping within the CeO2 lattice, causing distortions and forming Pd-O-Ce or Ni-O-Ce structures. These structures promoted oxygen vacancy formation in CeO2, and this was further confirmed by the Raman and XPS results. Consequently, the PdNi-H catalyst demonstrated an excellent redox ability and catalytic activity, achieving lower ignition and complete methane burning temperatures at 282 and 387 °C, respectively. The highly dispersed PdNi species played a pivotal role in activating methane for enhanced redox ability. Additionally, the narrow size distribution range contributed to more vacancies on the surface of CeO2, as confirmed by the XPS results, thereby facilitating the activation of gas phase oxygen to form oxygen species (O2−). This collaborative catalytic approach presents a promising strategy for developing efficient and stable methane combustion catalysts at low temperatures.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"8 20","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139148877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Layered double hydroxides (LDHs) have emerged as promising catalysts for various acid–base catalytic reactions. Due to their unique structure and regulatable dual acid–base properties, they offer more environmentally friendly and sustainable alternatives to traditional liquid acid and base catalysts. This study introduces the structural composition, preparation methods, and acid–base catalytic properties of LDH-based catalysts. Recent application progress in LDHs and rehydrated LDHs, LDH-based metal nanocatalysts, and LDH-based mixed metal oxide catalysts used as solid acid–base catalysts in acid–base green catalytic conversion is reviewed. The challenges and prospects of LDH-based catalysts as green and sustainable catalysts are summarized and proposed.
{"title":"Solid Acid–Base Catalysts Based on Layered Double Hydroxides Applied for Green Catalytic Transformations","authors":"Xiaolu You, Lishi Chen, Shan He, Guiju Zhang","doi":"10.3390/catal14010028","DOIUrl":"https://doi.org/10.3390/catal14010028","url":null,"abstract":"Layered double hydroxides (LDHs) have emerged as promising catalysts for various acid–base catalytic reactions. Due to their unique structure and regulatable dual acid–base properties, they offer more environmentally friendly and sustainable alternatives to traditional liquid acid and base catalysts. This study introduces the structural composition, preparation methods, and acid–base catalytic properties of LDH-based catalysts. Recent application progress in LDHs and rehydrated LDHs, LDH-based metal nanocatalysts, and LDH-based mixed metal oxide catalysts used as solid acid–base catalysts in acid–base green catalytic conversion is reviewed. The challenges and prospects of LDH-based catalysts as green and sustainable catalysts are summarized and proposed.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"21 43","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139148495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The synthesis of benzaldehyde, a compound widely utilized in food, medicine, and cosmetics, was achieved through a one-step catalytic hydrogenation using the cost-effective raw material, methyl benzoate. This process aligns with the principles of atom economy and green production. Despite the development of numerous high-performance catalysts by scholars, the challenge remains in achieving lower reaction temperatures, ideally below 400 °C. In this study, a series of MnOx/γ-Al2O3 catalysts were meticulously prepared using the precipitation-impregnation method. These catalysts featured supports calcined at various temperatures and distinct manganese active components. Characterization techniques such as X-ray diffraction (XRD), N2 physical adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), and NH3 temperature-programmed desorption (NH3-TPD) were employed to analyze the structure and surface properties of the catalysts. Notably, the optimized reaction temperature was found to be 360 °C. The catalyst exhibited the most favorable performance when the calcination temperature of the support was 500 °C and the Mn/Al molar ratio reached 0.18. Under these conditions, the catalyst demonstrated the most suitable oxygen vacancy concentration, yielding impressive results: a conversion rate of 87.90% and a benzaldehyde selectivity of 86.1%. These achievements were attained at 360 °C, atmospheric pressure, a hydrogen to methyl benzoate molar ratio of 40:1, and a Gas Hourly Space Velocity (GHSV) of 800 h−1. This research underscores the potential for optimizing catalysts to enhance the efficiency and sustainability of benzaldehyde synthesis.
{"title":"Catalytic Hydrogenation Property of Methyl Benzoate to Benzyl Aldehyde over Manganese-Based Catalysts with Appropriate Oxygen Vacancies","authors":"Pengxiang Gao, Xiaoran Liu, Xindong Mu, Yan Zhang","doi":"10.3390/catal14010027","DOIUrl":"https://doi.org/10.3390/catal14010027","url":null,"abstract":"The synthesis of benzaldehyde, a compound widely utilized in food, medicine, and cosmetics, was achieved through a one-step catalytic hydrogenation using the cost-effective raw material, methyl benzoate. This process aligns with the principles of atom economy and green production. Despite the development of numerous high-performance catalysts by scholars, the challenge remains in achieving lower reaction temperatures, ideally below 400 °C. In this study, a series of MnOx/γ-Al2O3 catalysts were meticulously prepared using the precipitation-impregnation method. These catalysts featured supports calcined at various temperatures and distinct manganese active components. Characterization techniques such as X-ray diffraction (XRD), N2 physical adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), and NH3 temperature-programmed desorption (NH3-TPD) were employed to analyze the structure and surface properties of the catalysts. Notably, the optimized reaction temperature was found to be 360 °C. The catalyst exhibited the most favorable performance when the calcination temperature of the support was 500 °C and the Mn/Al molar ratio reached 0.18. Under these conditions, the catalyst demonstrated the most suitable oxygen vacancy concentration, yielding impressive results: a conversion rate of 87.90% and a benzaldehyde selectivity of 86.1%. These achievements were attained at 360 °C, atmospheric pressure, a hydrogen to methyl benzoate molar ratio of 40:1, and a Gas Hourly Space Velocity (GHSV) of 800 h−1. This research underscores the potential for optimizing catalysts to enhance the efficiency and sustainability of benzaldehyde synthesis.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"3 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139151772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Photoredox catalysis constitutes a flourishing and fascinating field of organic chemistry, enabling the efficient construction of a variety of non-traditional bonds [...]
{"title":"Recent Advances in Photoredox Catalysts","authors":"F. Dumur, J. Lalevée","doi":"10.3390/catal14010026","DOIUrl":"https://doi.org/10.3390/catal14010026","url":null,"abstract":"Photoredox catalysis constitutes a flourishing and fascinating field of organic chemistry, enabling the efficient construction of a variety of non-traditional bonds [...]","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"16 8","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139151619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Siwen Yuan, Xiao Zhu, Mingxin Zhu, Hua Zhou, Shunlong Pan
Heterogeneous catalysis ozonation technology can achieve efficient treatment of refractory organics in industrial wastewater due to its advantages including fast reaction speed, high ozone utilization rate, low catalyst loss and low cost and has a broad application prospect. The development of efficient and stable heterogeneous ozone catalytic materials is the key to promoting the application of this technology in industrial wastewater treatment. Based on this, an Mn/Al2O3 catalyst was successfully prepared by impregnation method using 3~5 mm γ-Al2O3 pellets as the carrier, and the surface morphology characteristics, elemental state and phase composition of the catalyst were investigated by SEM-EDX, XRD and XPS. The results showed that Mn was successfully loaded onto the surface of a γ-Al2O3 carrier. On this basis, intermittent single factor experiments were conducted to systematically investigate the effects of catalyst dosage, pH, and ozone concentration on the catalytic performance of phenol. It was found that under the optimal conditions of a catalyst dosage of 100 g (filling height of 14.2 cm), pH of 7, and ozone concentration of 4 mg/L (gas volume of 1 L/min), the removal efficiencies of 800 mL 100 mg/L of simulated phenol wastewater reached 100% after 60 min of reaction. The removal efficiencies of the catalyst still reached 95.8% within 60 min even after the fifth cycle reaction, indicating excellent reusability of the catalyst. This work provides a facile strategy for the treatment of refractory organics in industrial wastewater.
{"title":"Enhanced Catalytic Ozonation of Phenol Degradation by Mn-Loaded γ-Al2O3 Catalyst: A Facile Strategy for Treating Organic Wastewater","authors":"Siwen Yuan, Xiao Zhu, Mingxin Zhu, Hua Zhou, Shunlong Pan","doi":"10.3390/catal14010029","DOIUrl":"https://doi.org/10.3390/catal14010029","url":null,"abstract":"Heterogeneous catalysis ozonation technology can achieve efficient treatment of refractory organics in industrial wastewater due to its advantages including fast reaction speed, high ozone utilization rate, low catalyst loss and low cost and has a broad application prospect. The development of efficient and stable heterogeneous ozone catalytic materials is the key to promoting the application of this technology in industrial wastewater treatment. Based on this, an Mn/Al2O3 catalyst was successfully prepared by impregnation method using 3~5 mm γ-Al2O3 pellets as the carrier, and the surface morphology characteristics, elemental state and phase composition of the catalyst were investigated by SEM-EDX, XRD and XPS. The results showed that Mn was successfully loaded onto the surface of a γ-Al2O3 carrier. On this basis, intermittent single factor experiments were conducted to systematically investigate the effects of catalyst dosage, pH, and ozone concentration on the catalytic performance of phenol. It was found that under the optimal conditions of a catalyst dosage of 100 g (filling height of 14.2 cm), pH of 7, and ozone concentration of 4 mg/L (gas volume of 1 L/min), the removal efficiencies of 800 mL 100 mg/L of simulated phenol wastewater reached 100% after 60 min of reaction. The removal efficiencies of the catalyst still reached 95.8% within 60 min even after the fifth cycle reaction, indicating excellent reusability of the catalyst. This work provides a facile strategy for the treatment of refractory organics in industrial wastewater.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"58 23","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139151041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aromatic volatile organic compounds (VOCs) are toxic to public health and contribute to global air pollution; thus, it is urgent to control VOC emissions. Catalytic oxidation technology has been widely investigated to eliminate aromatic VOCs; this technology exhibits high catalytic efficiency even at low temperatures. However, the reaction mechanism of aromatic VOCs’ total oxidation over metal-oxide-based catalysts, which is of great significance in the design of catalysts, is not yet clear. In this study, we systemically calculated the catalytic oxidation mechanism of toluene over the Ce0.875Zr0.125O2 catalyst using density functional theory (DFT). The results show that toluene first loses hydrogen from the methyl group via oxy-dehydrogenation and is gradually oxidized by lattice or adsorbed oxygen to benzyl alcohol, benzaldehyde, and benzoic acid following the Mars-van Krevelen (MVK) mechanism. Afterwards, there is a decarboxylation step to produce phenyl, which is further oxidized to benzoquinone. The rate-determining step then proceeds via the ring-opening reaction, leading to the formation of small molecule intermediates, which are finally oxidized to CO2 and H2O. This work may provide atomic-scale insight into the role of lattice and adsorbed oxygen in catalytic oxidation reactions.
{"title":"Catalytic Oxidation Mechanism of Toluene on the Ce0.875Zr0.125O2 (110) Surface","authors":"Yuning Leng, X. Cao, Xiaomin Sun, Chenxi Zhang","doi":"10.3390/catal14010022","DOIUrl":"https://doi.org/10.3390/catal14010022","url":null,"abstract":"Aromatic volatile organic compounds (VOCs) are toxic to public health and contribute to global air pollution; thus, it is urgent to control VOC emissions. Catalytic oxidation technology has been widely investigated to eliminate aromatic VOCs; this technology exhibits high catalytic efficiency even at low temperatures. However, the reaction mechanism of aromatic VOCs’ total oxidation over metal-oxide-based catalysts, which is of great significance in the design of catalysts, is not yet clear. In this study, we systemically calculated the catalytic oxidation mechanism of toluene over the Ce0.875Zr0.125O2 catalyst using density functional theory (DFT). The results show that toluene first loses hydrogen from the methyl group via oxy-dehydrogenation and is gradually oxidized by lattice or adsorbed oxygen to benzyl alcohol, benzaldehyde, and benzoic acid following the Mars-van Krevelen (MVK) mechanism. Afterwards, there is a decarboxylation step to produce phenyl, which is further oxidized to benzoquinone. The rate-determining step then proceeds via the ring-opening reaction, leading to the formation of small molecule intermediates, which are finally oxidized to CO2 and H2O. This work may provide atomic-scale insight into the role of lattice and adsorbed oxygen in catalytic oxidation reactions.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"39 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139153255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xi Liu, Yuankai Shao, Xiaoning Ren, Anqi Dong, Kaixiang Li, Bingjie Zhou, Chunqing Yang, Yatao Liu, Zhenguo Li
Three-way catalyst (TWC) is the mainstream technology for stoichiometric natural gas vehicle gas emission purification to meet the China VI emission standard for heavy-duty vehicles. Due to the high price of Pd-Rh TWC widely used at present, it is of great significance to develop cheaper Pt-only catalysts as substitutes. However, there are few studies on Pt-only TWC, especially for natural gas vehicles. It remains a formidable challenge to develop Pt-only TWC with excellent activity and stability. In this study, we significantly improved the catalytic performance of Pt/CeO2 TWC through thermal treatment, especially steam treatment at 800 °C, and used XRD, TEM, H2-TPR, and XPS techniques to investigate how Pt/CeO2 can be activated via these treatments. Our results suggested that after these treatments, CeO2 crystallites sintered slightly, while platinum particles remained highly dispersed. Moreover, these treatments also weakened the Pt-CeO2 interaction, promoted the formation of oxygen vacancies in CeO2 support, and generated a new type of active surface oxygen in the vicinity of Ptδ+, thus improving the activity of the catalyst. After 800 °C steam treatment, the T50 of CH4 and NO decreased by 31 and 36 °C, respectively. The results obtained in this study provide implications for the synthesis of efficient Pt-based catalysts.
{"title":"Steam Treatment Promotion on the Performance of Pt/CeO2 Three-Way Catalysts for Emission Control of Natural Gas-Fueled Vehicles","authors":"Xi Liu, Yuankai Shao, Xiaoning Ren, Anqi Dong, Kaixiang Li, Bingjie Zhou, Chunqing Yang, Yatao Liu, Zhenguo Li","doi":"10.3390/catal14010017","DOIUrl":"https://doi.org/10.3390/catal14010017","url":null,"abstract":"Three-way catalyst (TWC) is the mainstream technology for stoichiometric natural gas vehicle gas emission purification to meet the China VI emission standard for heavy-duty vehicles. Due to the high price of Pd-Rh TWC widely used at present, it is of great significance to develop cheaper Pt-only catalysts as substitutes. However, there are few studies on Pt-only TWC, especially for natural gas vehicles. It remains a formidable challenge to develop Pt-only TWC with excellent activity and stability. In this study, we significantly improved the catalytic performance of Pt/CeO2 TWC through thermal treatment, especially steam treatment at 800 °C, and used XRD, TEM, H2-TPR, and XPS techniques to investigate how Pt/CeO2 can be activated via these treatments. Our results suggested that after these treatments, CeO2 crystallites sintered slightly, while platinum particles remained highly dispersed. Moreover, these treatments also weakened the Pt-CeO2 interaction, promoted the formation of oxygen vacancies in CeO2 support, and generated a new type of active surface oxygen in the vicinity of Ptδ+, thus improving the activity of the catalyst. After 800 °C steam treatment, the T50 of CH4 and NO decreased by 31 and 36 °C, respectively. The results obtained in this study provide implications for the synthesis of efficient Pt-based catalysts.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"8 2","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper studies the composition and properties of shells of bivalve mollusks (Crenomytilus grayanus, Callista brevisiphonata, and Mizuhopecten yessoensis) from coastal discharges with a view to the possibility of their use in photocatalytic water treatment systems. The clam shells are considered in terms of application in the form of a powder material as a precursor for creating photocatalysts, and also as a carrier of photocatalytic coatings. It was shown that the main phase composing the shell material was calcium carbonate in two crystallographic modifications—calcite and aragonite. The presence of inorganic impurities in all studied clam shells did not exceed one mass percent. The main share was made up of elements included in the composition of calcium carbonate, which confirmed the high bio-indifference of the materials under study. Depending on the physiological and environmental features of the structure of clam shells, different contents of the organic component in their composition were observed. The granulometric characteristics of crushed clam shells (average diameter, specific surface area, and distribution modality) were studied. It was shown that the maximum values of bending strength of 5 MPa and compressive strength of 2 MPa are characterized by Mizuhopecten yessoensis shells with the lowest porosity of 2.91%. The features of sorption and photosorption processes of both whole and crushed shells in relation to four organic dyes at different temperatures and degrees of illumination were studied. Based on crushed shells of Mizuhopecten Yessoensis and titanium dioxide, functional materials (CaxTiyOz) were obtained, and their morphology and photocatalytic properties were studied. An example of the practical use of clam shells as a carrier of a photocatalytic coating is given.
{"title":"Study of the Composition and Properties of Bivalve Mollusk Shells as Promising Bio-Indifferent Materials for Photocatalytic Applications (Example of Practical Use)","authors":"Aleksey V. Zaitsev, Ivan A. Astapov","doi":"10.3390/catal14010016","DOIUrl":"https://doi.org/10.3390/catal14010016","url":null,"abstract":"This paper studies the composition and properties of shells of bivalve mollusks (Crenomytilus grayanus, Callista brevisiphonata, and Mizuhopecten yessoensis) from coastal discharges with a view to the possibility of their use in photocatalytic water treatment systems. The clam shells are considered in terms of application in the form of a powder material as a precursor for creating photocatalysts, and also as a carrier of photocatalytic coatings. It was shown that the main phase composing the shell material was calcium carbonate in two crystallographic modifications—calcite and aragonite. The presence of inorganic impurities in all studied clam shells did not exceed one mass percent. The main share was made up of elements included in the composition of calcium carbonate, which confirmed the high bio-indifference of the materials under study. Depending on the physiological and environmental features of the structure of clam shells, different contents of the organic component in their composition were observed. The granulometric characteristics of crushed clam shells (average diameter, specific surface area, and distribution modality) were studied. It was shown that the maximum values of bending strength of 5 MPa and compressive strength of 2 MPa are characterized by Mizuhopecten yessoensis shells with the lowest porosity of 2.91%. The features of sorption and photosorption processes of both whole and crushed shells in relation to four organic dyes at different temperatures and degrees of illumination were studied. Based on crushed shells of Mizuhopecten Yessoensis and titanium dioxide, functional materials (CaxTiyOz) were obtained, and their morphology and photocatalytic properties were studied. An example of the practical use of clam shells as a carrier of a photocatalytic coating is given.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"273 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139161022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microbial xylanase has wide application in bioenergy, animal feed, environmental protection, the pulp and paper industry, and agricultural development. In this study, three xylanases from the microbiota of T. fuciformis with its companion strains were identified by metagenomics sequencing. The three enzymes were subjected to cloning and expression in E. coli or P. pastoris, purification, and characterization for their properties. The results showed that AsXyn1, from Annulohypoxylon stygium, among the three enzymes possessed high thermostability at 40 °C and broad pH tolerance in the range of 2.0–10.0, exhibiting its application potential. Furthermore, it was found that post-translational modification (such as glycosylation) of AsXyn1 enzyme modulated its activity, kinetic parameters, and thermostability. These results and findings provided a hint for enzyme modification and design in future.
{"title":"Mining, Identification, and Characterization of Three Xylanases from the Microbiota of T. fuciformis with Its Companion Strains","authors":"Yanhuan Lin, Changle Li, Chenxin Wei, Hui Lin, Liaoyuan Zhang","doi":"10.3390/catal14010015","DOIUrl":"https://doi.org/10.3390/catal14010015","url":null,"abstract":"Microbial xylanase has wide application in bioenergy, animal feed, environmental protection, the pulp and paper industry, and agricultural development. In this study, three xylanases from the microbiota of T. fuciformis with its companion strains were identified by metagenomics sequencing. The three enzymes were subjected to cloning and expression in E. coli or P. pastoris, purification, and characterization for their properties. The results showed that AsXyn1, from Annulohypoxylon stygium, among the three enzymes possessed high thermostability at 40 °C and broad pH tolerance in the range of 2.0–10.0, exhibiting its application potential. Furthermore, it was found that post-translational modification (such as glycosylation) of AsXyn1 enzyme modulated its activity, kinetic parameters, and thermostability. These results and findings provided a hint for enzyme modification and design in future.","PeriodicalId":9794,"journal":{"name":"Catalysts","volume":"15 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139159831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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