Pub Date : 2024-10-28DOI: 10.1016/j.cattod.2024.115113
Wei Lv , Yao Wang , Hong Chen , Yongqi Tang , Yongdan Li
Nitrogen atom-doped biomass carbon prepared from corn stover is a newly discovered metal-free catalyst that shows good activity on the selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF). Here, the presence of graphitic nitrogen on the catalyst surface activated the oxygen adsorbed on the carbon sites next to the graphitic nitrogen in the carbon material and promoted the formation of oxygen radicals on the surface-active sites, improving the HMF oxidation process. The results show that the catalyst NC-800 reacted with acetonitrile as the reaction solvent at 110 °C and 1.0 MPa O2 for 8 h to obtain 93.0 % HMF conversion and 94.4 % DFF selectivity, and the 5-HMF conversion and DFF selectivity were maintained at more than 85 % after five cyclic tests, with excellent cyclic stability. One of the main factors influencing the material flaws is the variation in pyrolysis temperature. Using maize stover, a readily available and renewable biomass, in the catalytic oxidation of biomass platform compounds may improve biomass utilization more extensively.
{"title":"The application of graphitic nitrogen from corn stover for the selective catalytic oxidation of 5-hydroxymethyl furfural","authors":"Wei Lv , Yao Wang , Hong Chen , Yongqi Tang , Yongdan Li","doi":"10.1016/j.cattod.2024.115113","DOIUrl":"10.1016/j.cattod.2024.115113","url":null,"abstract":"<div><div>Nitrogen atom-doped biomass carbon prepared from corn stover is a newly discovered metal-free catalyst that shows good activity on the selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF). Here, the presence of graphitic nitrogen on the catalyst surface activated the oxygen adsorbed on the carbon sites next to the graphitic nitrogen in the carbon material and promoted the formation of oxygen radicals on the surface-active sites, improving the HMF oxidation process. The results show that the catalyst NC-800 reacted with acetonitrile as the reaction solvent at 110 °C and 1.0 MPa O<sub>2</sub> for 8 h to obtain 93.0 % HMF conversion and 94.4 % DFF selectivity, and the 5-HMF conversion and DFF selectivity were maintained at more than 85 % after five cyclic tests, with excellent cyclic stability. One of the main factors influencing the material flaws is the variation in pyrolysis temperature. Using maize stover, a readily available and renewable biomass, in the catalytic oxidation of biomass platform compounds may improve biomass utilization more extensively.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115113"},"PeriodicalIF":5.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.cattod.2024.115112
Lianghuan Wei , Ning Lin , Jixiang Cai , Fang Huang , Zejun Liu , Hengli Qian , Chao Xie , Weizun Li , Meiting Ju , Qidong Hou
The production of methane-enriched gas via thermo-chemical process is an important approach for biomass valorization. However, current pyrolysis processes generally give low yield of value-added gas product. Herein, a series of Ni-based materials with hydroxyapatite (HAP) and titanium silicate (TS) as supports were prepared and investigated as catalysts to boost CH4 production from pyrolysis-steam reforming of corn stalk. The surface element composition, chemical state and crystal structure of materials were characterized by transmission electron microscope (TEM), N2 adsorption-desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The expected loading of Ni, La and Ce were successfully loaded onto HAP via simple impregnation method, while the loading of active metals on TS is finite. Ni-5La2O3/HAP exhibited the best catalytic activity for pyrolysis-steam reforming of corn stalk, attaining CH4 yield (19.41 mmol/g) that is 89.9 % and 46.2 % higher than control experiment and Ni-5CeO2/MCM-41, indicating that loading high-density Ni and La species onto HAP supports can greatly boost the CH4 formation. However, the catalysts lost activity obviously during recycling experiment probably due to carbon accumulation.
通过热化学工艺生产富含甲烷的气体是生物质增值的重要方法。然而,目前的热解工艺一般产生的高附加值气体产品产量较低。本文制备了一系列以羟基磷灰石(HAP)和硅酸钛(TS)为载体的镍基材料,并将其作为催化剂进行了研究,以提高玉米秸秆热解-蒸汽转化过程中的甲烷产量。通过透射电子显微镜(TEM)、N2 吸附-解吸、X 射线衍射(XRD)和 X 射线光电子能谱(XPS)分析对材料的表面元素组成、化学状态和晶体结构进行了表征。通过简单的浸渍法,镍、镧和铈的预期负载成功地负载到了 HAP 上,而活性金属在 TS 上的负载是有限的。Ni-5La2O3/HAP 在玉米秸秆热解-蒸汽转化过程中表现出最好的催化活性,CH4 产率(19.41 mmol/g)比对照实验和 Ni-5CeO2/MCM-41 分别高出 89.9% 和 46.2%,这表明在 HAP 载体上负载高密度的 Ni 和 La 物种能极大地促进 CH4 的生成。然而,可能由于积碳的原因,催化剂在循环实验过程中活性明显下降。
{"title":"Hydroxyapatite supported Ni and La2O3 boost methane-enriched gas production from pyrolysis-steam reforming of corn stalk","authors":"Lianghuan Wei , Ning Lin , Jixiang Cai , Fang Huang , Zejun Liu , Hengli Qian , Chao Xie , Weizun Li , Meiting Ju , Qidong Hou","doi":"10.1016/j.cattod.2024.115112","DOIUrl":"10.1016/j.cattod.2024.115112","url":null,"abstract":"<div><div>The production of methane-enriched gas via thermo-chemical process is an important approach for biomass valorization. However, current pyrolysis processes generally give low yield of value-added gas product. Herein, a series of Ni-based materials with hydroxyapatite (HAP) and titanium silicate (TS) as supports were prepared and investigated as catalysts to boost CH<sub>4</sub> production from pyrolysis-steam reforming of corn stalk. The surface element composition, chemical state and crystal structure of materials were characterized by transmission electron microscope (TEM), N<sub>2</sub> adsorption-desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The expected loading of Ni, La and Ce were successfully loaded onto HAP via simple impregnation method, while the loading of active metals on TS is finite. Ni-5La<sub>2</sub>O<sub>3</sub>/HAP exhibited the best catalytic activity for pyrolysis-steam reforming of corn stalk, attaining CH<sub>4</sub> yield (19.41 mmol/g) that is 89.9 % and 46.2 % higher than control experiment and Ni-5CeO<sub>2</sub>/MCM-41, indicating that loading high-density Ni and La species onto HAP supports can greatly boost the CH<sub>4</sub> formation. However, the catalysts lost activity obviously during recycling experiment probably due to carbon accumulation.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115112"},"PeriodicalIF":5.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-28DOI: 10.1016/j.cattod.2024.115109
Kelvin A. Sanoja-López, Dayanara D. Salinas-Echeverría, Rafael Luque
This study focuses on the tandem multi-step valorization of 5-hydroxymethylfurfural (HMF) to valuable furanic derivatives using a catalytic process with 10 % Pd/C in continuous flow under mild operating conditions. The results demonstrate the selective conversion of 5-HMF to furfuryl alcohol with yields exceeding 99 % under mild conditions and short times of reaction, subsequently followed by the conversion of furfuryl alcohol to valuable products (imines) via oxidative coupling. This continuous flow approach offers several advantages over batch methods, including the ability to achieve high yields with precise control of parameters such as temperature, pressure, and flow rate, thereby facilitating process optimization and scalability.
{"title":"Continuous Flow valorization of furanics: From decarbonylation of 5-Hydroxymethyl-furfural to furfuryl alcohol conversion into valuable oxidative coupling products","authors":"Kelvin A. Sanoja-López, Dayanara D. Salinas-Echeverría, Rafael Luque","doi":"10.1016/j.cattod.2024.115109","DOIUrl":"10.1016/j.cattod.2024.115109","url":null,"abstract":"<div><div>This study focuses on the tandem multi-step valorization of 5-hydroxymethylfurfural (HMF) to valuable furanic derivatives using a catalytic process with 10 % Pd/C in continuous flow under mild operating conditions. The results demonstrate the selective conversion of 5-HMF to furfuryl alcohol with yields exceeding 99 % under mild conditions and short times of reaction, subsequently followed by the conversion of furfuryl alcohol to valuable products (imines) via oxidative coupling. This continuous flow approach offers several advantages over batch methods, including the ability to achieve high yields with precise control of parameters such as temperature, pressure, and flow rate, thereby facilitating process optimization and scalability.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115109"},"PeriodicalIF":5.2,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.cattod.2024.115105
Sneha R. Shetty , Ganapati D. Yadav
Hydrogenation of xylose to xylitol is commercially attractive. The use of water as well as aqueous isopropanol as solvent using a novel robust catalyst was targeted in this work. This work showed that a nickel-alumina catalyst supported on hexagonal mesoporous silica (HMS) can effectively transform lignocellulose-derived xylose fraction to the value-added product, xylitol. HMS support was modified by simultaneous impregnating nickel (6 wt%) and alumina (4 wt%) which was subsequently oxidized. The catalyst was evaluated for its hydrogenation ability of xylose to xylitol. Identical reactions were carried out with HMS, alumina, Al/HMS and Ni/HMS to ascertain the activity of each moiety in the reaction. Before the reaction, the catalyst was reduced in a tubular reactor in the presence of hydrogen. Reaction parameters such as speed of agitation, type of precursor, metal loading, catalyst loading, solvent, concentration and temperature were studied and optimized. At 130℃ and 20 bar H2, initial xylose concentration of 0.2 mmol/mL with water: isopropanol (1:1 v/v) mixture as solvent, conversion of xylose was found to be 98 % with a selectivity of 97 % towards xylitol. Comparison was also made with water alone as a solvent. A kinetic study of the reaction was performed. The transformation of xylose to xylitol using this novel catalyst is a green process since it entails substantially lower metal loading when compared to the conventional Raney nickel catalysts, it does not involve the use of noble metals such as Pt, Pd, Rh or Ru, and also does not suffer from the problem of metal leaching, making it superior to those catalysts reported yet.
将木糖加氢转化为木糖醇具有商业吸引力。本研究以水和异丙醇水溶液为溶剂,并使用新型强效催化剂为目标。这项研究表明,六方介孔二氧化硅(HMS)支撑的镍-氧化铝催化剂可以有效地将木质纤维素衍生的木糖部分转化为高附加值产品木糖醇。通过同时浸渍镍(6 wt%)和氧化铝(4 wt%)对 HMS 载体进行改性,然后对其进行氧化。对该催化剂将木糖氢化为木糖醇的能力进行了评估。用 HMS、氧化铝、Al/HMS 和 Ni/HMS 进行了相同的反应,以确定每个分子在反应中的活性。反应前,催化剂在有氢气存在的管式反应器中进行还原。对搅拌速度、前驱体类型、金属负载、催化剂负载、溶剂、浓度和温度等反应参数进行了研究和优化。在 130℃ 和 20 bar H2 条件下,以水:异丙醇(1:1 v/v)混合物为溶剂,木糖初始浓度为 0.2 mmol/mL,木糖转化率为 98%,对木糖醇的选择性为 97%。此外,还与单独用水作为溶剂进行了比较。对反应进行了动力学研究。使用这种新型催化剂将木糖转化为木糖醇是一种绿色工艺,因为与传统的雷尼镍催化剂相比,这种催化剂的金属负载量要低得多,而且不需要使用铂、钯、铑或钌等贵金属,也没有金属浸出的问题,因此比目前报道的催化剂更为优越。
{"title":"Sustainable hydrogenation of xylose to xylitol using nickel-alumina catalysts supported on hexagonal mesoporous silica in water vis-à-vis aqueous isopropanol as solvent","authors":"Sneha R. Shetty , Ganapati D. Yadav","doi":"10.1016/j.cattod.2024.115105","DOIUrl":"10.1016/j.cattod.2024.115105","url":null,"abstract":"<div><div>Hydrogenation of xylose to xylitol is commercially attractive. The use of water as well as aqueous isopropanol as solvent using a novel robust catalyst was targeted in this work. This work showed that a nickel-alumina catalyst supported on hexagonal mesoporous silica (HMS) can effectively transform lignocellulose-derived xylose fraction to the value-added product, xylitol. HMS support was modified by simultaneous impregnating nickel (6 wt%) and alumina (4 wt%) which was subsequently oxidized. The catalyst was evaluated for its hydrogenation ability of xylose to xylitol. Identical reactions were carried out with HMS, alumina, Al/HMS and Ni/HMS to ascertain the activity of each moiety in the reaction. Before the reaction, the catalyst was reduced in a tubular reactor in the presence of hydrogen. Reaction parameters such as speed of agitation, type of precursor, metal loading, catalyst loading, solvent, concentration and temperature were studied and optimized. At 130℃ and 20 bar H<sub>2</sub>, initial xylose concentration of 0.2 mmol/mL with water: isopropanol (1:1 v/v) mixture as solvent, conversion of xylose was found to be 98 % with a selectivity of 97 % towards xylitol. Comparison was also made with water alone as a solvent. A kinetic study of the reaction was performed. The transformation of xylose to xylitol using this novel catalyst is a green process since it entails substantially lower metal loading when compared to the conventional Raney nickel catalysts, it does not involve the use of noble metals such as Pt, Pd, Rh or Ru, and also does not suffer from the problem of metal leaching, making it superior to those catalysts reported yet.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"446 ","pages":"Article 115105"},"PeriodicalIF":5.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.cattod.2024.115104
Xuerui Zheng , Hisahiro Einaga
Manganese oxide catalysts with different structures and loading levels were supported on zeolite Y catalysts using a dry impregnation method for the oxidation of low concentrations of benzene with ozone. X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) studies revealed that manganese oxide was highly dispersed on the zeolite in a low oxidation state for those prepared with the acetate precursor, and highly oxidized and aggregated manganese oxide for those prepared with the nitrate precursor. In the reaction at 70 ℃, the benzene oxidation rate, CO2 selectivity, and ozone/benzene decomposition ratio were independent of the manganese loading, manganese precursor, and zeolite Y porosity. These catalytic properties were found to be less dependent on the manganese oxide structure. A slight increase in the reaction temperature enhanced both the catalytic activity and the catalyst performance, while the presence of water vapor had no significant impact. The XAFS analysis of the spent catalysts indicated that during the benzene decomposition reaction, the structure of the manganese oxide loaded on the catalyst was altered, and its oxidation state was uniformly reduced.
采用干法浸渍法在沸石 Y 催化剂上支撑了不同结构和负载水平的氧化锰催化剂,用于用臭氧氧化低浓度苯。X 射线衍射(XRD)和 X 射线吸收精细结构(XAFS)研究表明,用醋酸盐前驱体制备的氧化锰以低氧化态高度分散在沸石上,而用硝酸盐前驱体制备的氧化锰则高度氧化和聚集。在 70 ℃ 的反应中,苯氧化率、二氧化碳选择性和臭氧/苯分解率与锰负载量、锰前体和沸石 Y 的孔隙率无关。这些催化特性对氧化锰结构的依赖性较小。反应温度略微升高可提高催化活性和催化剂性能,而水蒸气的存在则无明显影响。对废催化剂的 XAFS 分析表明,在苯分解反应过程中,催化剂上负载的氧化锰结构发生了改变,其氧化态均匀降低。
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Pub Date : 2024-10-24DOI: 10.1016/j.cattod.2024.115107
Victória Gonçalves F Pereira , Ana Serrano-Lotina , Raquel Portela , Miguel A. Bañares , Clarissa Perdomo Rodrigues , Fabio Souza Toniolo
Promotion of Ni-based catalysts supported on cordierite monoliths was investigated for methane steam reforming. First, cordierite was coated by ɣ-Al2O3, and then the catalyst components were deposited by successive wet impregnation, obtaining: NiAl/cordierite; NiCeAl/cordierite; NiCeLaAl/cordierite and NiCeZrAl/cordierite. The monolithic catalysts were characterized by adherence test, Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), N2 physisorption, Temperature-Programmed Reduction (TPR), CO chemisorption, as well as by in situ and operando Raman spectroscopy. The catalyst layer showed very good adherence and distribution of the components over the cordierite surface. The catalysts presented high activity between 600 and 800 °C at a H2O/CH4 molar ratio=1.5, except for NiCeAl/cordierite, which obtained lower methane conversion, associated with its lower nickel dispersion. The catalysts showed high stability under extreme conditions for carbon deposition (600 °C and H2O/CH4=1), over 90 h on stream. Raman spectroscopy revealed the presence of oxygen vacancies, which may be increased during ceria reduction, highlighting the potential of these catalysts to enhance the resistance to deactivation by carbon deposition in long-term tests.
研究了堇青石整体支撑的镍基催化剂对甲烷蒸汽转化的促进作用。首先用ɣ-Al2O3 对堇青石进行包覆,然后通过连续湿法浸渍沉积催化剂组分,得到了NiAl/堇青石、NiCeAl/堇青石、NiCeLaAl/堇青石和 NiCeZrAl/堇青石。通过附着力测试、扫描电子显微镜与能量色散 X 射线光谱(SEM-EDX)、N2 物理吸附、温度编程还原(TPR)、CO 化学吸附以及原位和操作拉曼光谱,对整体催化剂进行了表征。催化剂层在堇青石表面显示出非常好的附着性和组分分布。在 H2O/CH4 摩尔比=1.5 的条件下,催化剂在 600 至 800 °C 之间表现出较高的活性,但 NiCeAl/cordierite 除外,其甲烷转化率较低,这与其镍分散度较低有关。在碳沉积的极端条件下(600 °C,H2O/CH4=1),催化剂在90小时内显示出很高的稳定性。拉曼光谱显示存在氧空位,这可能在铈还原过程中增加,突出了这些催化剂在长期测试中提高抗碳沉积失活能力的潜力。
{"title":"Ni/Al2O3 promoted by CeO2, CeO2-La2O3, and CeO2-ZrO2 supported on cordierite monoliths for methane steam reforming","authors":"Victória Gonçalves F Pereira , Ana Serrano-Lotina , Raquel Portela , Miguel A. Bañares , Clarissa Perdomo Rodrigues , Fabio Souza Toniolo","doi":"10.1016/j.cattod.2024.115107","DOIUrl":"10.1016/j.cattod.2024.115107","url":null,"abstract":"<div><div>Promotion of Ni-based catalysts supported on cordierite monoliths was investigated for methane steam reforming. First, cordierite was coated by ɣ-Al<sub>2</sub>O<sub>3,</sub> and then the catalyst components were deposited by successive wet impregnation, obtaining: NiAl/cordierite; NiCeAl/cordierite; NiCeLaAl/cordierite and NiCeZrAl/cordierite. The monolithic catalysts were characterized by adherence test, Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), N<sub>2</sub> physisorption, Temperature-Programmed Reduction (TPR), CO chemisorption, as well as by <em>in situ</em> and <em>operando</em> Raman spectroscopy. The catalyst layer showed very good adherence and distribution of the components over the cordierite surface. The catalysts presented high activity between 600 and 800 °C at a H<sub>2</sub>O/CH<sub>4</sub> molar ratio=1.5, except for NiCeAl/cordierite, which obtained lower methane conversion, associated with its lower nickel dispersion. The catalysts showed high stability under extreme conditions for carbon deposition (600 °C and H<sub>2</sub>O/CH<sub>4</sub>=1), over 90 h on stream. Raman spectroscopy revealed the presence of oxygen vacancies, which may be increased during ceria reduction, highlighting the potential of these catalysts to enhance the resistance to deactivation by carbon deposition in long-term tests.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115107"},"PeriodicalIF":5.2,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.cattod.2024.115110
T.A. Zepeda
Here reports the modulation of selectivity in Fischer-Tropsch synthesis through the control of cobalt reducibility within a hexagonal mesoporous silica (HMS) framework. Cobalt loading, varied from 3 % to 12.5 wt%, generated different surface and bulk cobalt species that interact variably with the support, significantly influencing their reducibility and the resultant catalytic behavior. This variation significantly affected the reducibility of the cobalt species, influencing on the catalytic behavior. The control of reducibility and stability of Co species is contingent on the cobalt loading. Higher cobalt content enhances the reducibility of Co species, shifting product selectivity from long-chain hydrocarbons to lighter olefins and oxygenates. At a TOS of 4 h, the active phase predominantly involves metallic Co species, while CO2 and oxygenates formation is closely linked to the pair Co0-Co2+ active phase. After a TOS of 120 h, samples with higher cobalt content (6.1–15.8 % wt.) exhibited notable deactivation and changes in selectivity and hydrocarbon distribution. These changes were associated with the formation of a Co2C phase, which inhibits methane formation and chain growth while enhancing the production of lower olefins and oxygenates through a synergistic interaction at the Co0 and Co2C interface, also improves the WGS reaction, thereby increasing CO2 selectivity.
本文报告了通过控制六方介孔二氧化硅(HMS)框架内的钴还原性来调节费托合成中的选择性。钴的负载量从 3% 到 12.5 wt% 不等,产生了不同的表面和块体钴物种,这些钴物种与支持物的相互作用各不相同,极大地影响了它们的还原性和由此产生的催化行为。这种变化极大地影响了钴物种的还原性,从而影响了催化行为。钴物种的还原性和稳定性取决于钴的负载量。钴含量越高,钴物种的还原性越强,产品选择性从长链烃类转向较轻的烯烃和含氧化合物。在 4 小时的总反应时间内,活性相主要涉及金属 Co 物种,而 CO2 和含氧化合物的形成则与一对 Co0-Co2+ 活性相密切相关。在 120 小时的 TOS 之后,钴含量较高的样品(6.1-15.8% wt.)表现出明显的失活以及选择性和碳氢化合物分布的变化。这些变化与 Co2C 相的形成有关,Co2C 相通过 Co0 和 Co2C 界面的协同作用,抑制了甲烷的形成和链增长,同时提高了低级烯烃和含氧化合物的产量,还改善了 WGS 反应,从而提高了二氧化碳的选择性。
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The progress in civilization can be related to the development of newer technological development and associated energy demand to run those systems. The personalized healthcare systems, the depletion of conventional fossil fuel reserve led us to think about alternative energy storage devices. Thus, it is important to develop energy storage materials with the property of good mechanical strength and stability for longer hours. Zn-air batteries (ZAB) show the promises to be an alternative of Li-air batteries for this purpose. ZABs can fulfill our need of stringent requirements such as high energy density, cost-effectiveness and it is safer as compared to Li-ion batteries. The stability of zinc in aqueous and air environments makes ZAB technology more reliable and effective for small to large-scale flexible electronics. To further enhance its efficiency, different scientific materials and methods have been developed over decades, of which this review provides detailed insight into the parameters and mechanisms related to the key components of the ZAB for enhancing the performance of ZAB. We summarized the working mechanism of overall reversible-ZABs and then independently we explained the mechanism and problems associated with cathode, anode, and electrolyte, followed by the current breakthrough related to each. Aspects such as role of optimal eg occupancy in bifunctional activity, inhibition of zinc dendrite, and gel polymer electrolytes with enhanced conductivity and strength are specifically highlighted. To facilitate a broad discussion among different research communities, important scientific hurdles and their potential solution related to R-ZABs are also summarized.
{"title":"Chemistry in rechargeable zinc-air battery: A mechanistic overview","authors":"Arkaj Singh, Ravinder Sharma, Akriti Gautam, Bhavnish Kumar, Sneha Mittal, Aditi Halder","doi":"10.1016/j.cattod.2024.115108","DOIUrl":"10.1016/j.cattod.2024.115108","url":null,"abstract":"<div><div>The progress in civilization can be related to the development of newer technological development and associated energy demand to run those systems. The personalized healthcare systems, the depletion of conventional fossil fuel reserve led us to think about alternative energy storage devices. Thus, it is important to develop energy storage materials with the property of good mechanical strength and stability for longer hours. Zn-air batteries (ZAB) show the promises to be an alternative of Li-air batteries for this purpose. ZABs can fulfill our need of stringent requirements such as high energy density, cost-effectiveness and it is safer as compared to Li-ion batteries. The stability of zinc in aqueous and air environments makes ZAB technology more reliable and effective for small to large-scale flexible electronics. To further enhance its efficiency, different scientific materials and methods have been developed over decades, of which this review provides detailed insight into the parameters and mechanisms related to the key components of the ZAB for enhancing the performance of ZAB. We summarized the working mechanism of overall reversible-ZABs and then independently we explained the mechanism and problems associated with cathode, anode, and electrolyte, followed by the current breakthrough related to each. Aspects such as role of optimal e<sub>g</sub> occupancy in bifunctional activity, inhibition of zinc dendrite, and gel polymer electrolytes with enhanced conductivity and strength are specifically highlighted. To facilitate a broad discussion among different research communities, important scientific hurdles and their potential solution related to R-ZABs are also summarized.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115108"},"PeriodicalIF":5.2,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.cattod.2024.115102
Sandeep Nigam , Chiranjib Majumder
Bimetallic clusters, as the name suggests, are known to act as bifunctional catalyst. Therefore, it is possible to tune the composition of the catalyst to achieve the best performance for a specific reaction. In the first part of this work, we explore the geometric and electronic structures of various Ag-Pt bimetallic clusters and find the right composition for ORR, one of the most sought-after reactions in the field of energy materials. We have considered Ag-Pt bimetallic clusters in both free and on Al2O3(0001) support. The results reveal that the equilibrium structures of the bimetallic AgnPtm (n+m ≤ 12 atoms) clusters are governed by a balance of competing interactions (Pt-Pt vs Ag-Pt vs cluster-support interactions). Whilst the isolated decamer cluster with 5:5 or 6:4 composition (Ag6Pt4 and Ag5Pt5) shows atomically segregated structures, Ag rich clusters (Ag9Pt1–3) prefer to form core-shell pattern where Pt forms the core surrounded by Ag atoms. In general, these clusters adopt pseudo-planar structure on alumina support following the surface template. Analysis of the electronic structure shows that Al2O3 surface induces significant broadening in the energy states of the bimetallic cluster, which in turn facilitates higher mixing between d-states of the Ag and Pt in the complex. Finally, the d-band centre descriptor model has been utilized to underscore the chemical reactivity of these bimetallic clusters. Remarkably, the Ag6Pt4@Al2O3 cluster with d-band centre at −2.68 eV is found to be in “just right” zone for ORR. This is further corroborated by the reduction (∼ 25 %) in oxidation reaction enthalpy of the Ag6Pt4@Al2O3 than standard Pt(111) catalytic surface.
双金属团簇,顾名思义,具有双功能催化剂的作用。因此,可以通过调节催化剂的组成来实现特定反应的最佳性能。在这项工作的第一部分,我们探索了各种银铂双金属团簇的几何和电子结构,并找到了用于 ORR(能源材料领域最热门的反应之一)的合适成分。我们研究了游离和Al2O3(0001)支撑下的银铂双金属团簇。研究结果表明,双金属 AgnPtm(n+m ≤ 12 个原子)团簇的平衡结构受相互竞争的相互作用(Pt-Pt 与 Ag-Pt 之间的相互作用以及团簇与支撑物之间的相互作用)的影响。组成比例为 5:5 或 6:4 的孤立十聚体团簇(Ag6Pt4 和 Ag5Pt5)显示出原子隔离结构,而富含 Ag 的团簇(Ag9Pt1-3)则倾向于形成核壳模式,其中铂形成核心,周围环绕着 Ag 原子。一般来说,这些团簇在氧化铝载体上按照表面模板采用伪平面结构。对电子结构的分析表明,Al2O3 表面使双金属团簇的能态显著拓宽,这反过来又促进了复合物中银和铂的 d 态之间的混合。最后,利用 d 带中心描述模型强调了这些双金属簇的化学反应活性。值得注意的是,发现 d 波段中心在 -2.68 eV 的 Ag6Pt4@Al2O3 簇处于 ORR 的 "恰到好处 "区域。与标准铂(111)催化表面相比,Ag6Pt4@Al2O3 的氧化反应焓降低了 25%,进一步证实了这一点。
{"title":"Tailoring reactivity of small Ag/Pt bimetallic cluster for ORR: A comprehensive study using density functional theory approach","authors":"Sandeep Nigam , Chiranjib Majumder","doi":"10.1016/j.cattod.2024.115102","DOIUrl":"10.1016/j.cattod.2024.115102","url":null,"abstract":"<div><div>Bimetallic clusters, as the name suggests, are known to act as bifunctional catalyst. Therefore, it is possible to tune the composition of the catalyst to achieve the best performance for a specific reaction. In the first part of this work, we explore the geometric and electronic structures of various Ag-Pt bimetallic clusters and find the right composition for ORR, one of the most sought-after reactions in the field of energy materials. We have considered Ag-Pt bimetallic clusters in both free and on Al<sub>2</sub>O<sub>3</sub>(0001) support. The results reveal that the equilibrium structures of the bimetallic Ag<sub>n</sub>Pt<sub>m</sub> (n+m ≤ 12 atoms) clusters are governed by a balance of competing interactions (<em>Pt-Pt vs Ag-Pt vs cluster-support interactions</em>). Whilst the isolated decamer cluster with 5:5 or 6:4 composition (Ag<sub>6</sub>Pt<sub>4</sub> and Ag<sub>5</sub>Pt<sub>5</sub>) shows atomically segregated structures, Ag rich clusters (Ag<sub>9</sub>Pt<sub>1–3</sub>) prefer to form core-shell pattern where Pt forms the core surrounded by Ag atoms. In general, these clusters adopt pseudo-planar structure on alumina support following the surface template. Analysis of the electronic structure shows that Al<sub>2</sub>O<sub>3</sub> surface induces significant broadening in the energy states of the bimetallic cluster, which in turn facilitates higher mixing between <em>d</em>-states of the Ag and Pt in the complex. Finally, the <em>d</em>-band centre descriptor model has been utilized to underscore the chemical reactivity of these bimetallic clusters. Remarkably, the Ag<sub>6</sub>Pt<sub>4</sub>@Al<sub>2</sub>O<sub>3</sub> cluster with <em>d</em>-band centre at −2.68 eV is found to be in “just right” zone for ORR. This is further corroborated by the reduction (∼ 25 %) in oxidation reaction enthalpy of the Ag<sub>6</sub>Pt<sub>4</sub>@Al<sub>2</sub>O<sub>3</sub> than standard Pt(111) catalytic surface.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115102"},"PeriodicalIF":5.2,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-21DOI: 10.1016/j.cattod.2024.115106
Luís Fernando Wentz Brum , Maurício Dalla Costa Rodrigues da Silva , Cristiane dos Santos , Giovani Pavoski , Denise Crocce Romano Espinosa , William Leonardo da Silva
Niobium is a metal that has been attracting great interest in producing high-technology materials, in which niobium oxide nanoparticles (Nb2O5-NPs) are inserted. In this context, the present study aims to develop and characterize structurally and morphologically niobium (V) oxide nanoparticles (Nb2O5-NPs) by the green synthesis method from pecan nutshell (C. illinoinensis) extract. Nb2O5-NPs were characterized by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and N2 porosimetry (BET/BJH method). The antioxidant potential of the pecan nutshell extract was determined for the quantification of phenolic compounds and flavonoids. The XRD diffractogram showed that the Nb2O5-NPs presented a semicrystalline structure with the presence of the pseudohexagonal phase of Nb2O5. The ATR-FTIR spectrum confirmed the presence of a band vibration of the Nb-O at 600 cm−1. The Nb2O5-NPs presented spherical morphology according to the SEM micrography with a specific surface area of 1.72 m2 g−1 and 36.31 nm pore diameter (isotherm type III) by the N2 porosimetry. The pecan nutshell extract showed the presence of polyphenols (336.8 mgAG mL−1) and flavonoids (200.1 mgCt mL−1), demonstrating the high potential to act as a bioreducing and stabilizing agent for the green synthesis of Nb2O5-NPs. Therefore, the green synthesis of Nb2O5-NPs is feasible with potential application in different fields.
{"title":"Green synthesis of niobium (V) oxide nanoparticles using pecan nutshell (Carya illinoinensis) and evaluation of its antioxidant activity","authors":"Luís Fernando Wentz Brum , Maurício Dalla Costa Rodrigues da Silva , Cristiane dos Santos , Giovani Pavoski , Denise Crocce Romano Espinosa , William Leonardo da Silva","doi":"10.1016/j.cattod.2024.115106","DOIUrl":"10.1016/j.cattod.2024.115106","url":null,"abstract":"<div><div>Niobium is a metal that has been attracting great interest in producing high-technology materials, in which niobium oxide nanoparticles (Nb<sub>2</sub>O<sub>5</sub>-NPs) are inserted. In this context, the present study aims to develop and characterize structurally and morphologically niobium (V) oxide nanoparticles (Nb<sub>2</sub>O<sub>5</sub>-NPs) by the green synthesis method from pecan nutshell (<em>C. illinoinensis</em>) extract. Nb<sub>2</sub>O<sub>5</sub>-NPs were characterized by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and N<sub>2</sub> porosimetry (BET/BJH method). The antioxidant potential of the pecan nutshell extract was determined for the quantification of phenolic compounds and flavonoids. The XRD diffractogram showed that the Nb<sub>2</sub>O<sub>5</sub>-NPs presented a semicrystalline structure with the presence of the pseudohexagonal phase of Nb<sub>2</sub>O<sub>5</sub>. The ATR-FTIR spectrum confirmed the presence of a band vibration of the Nb-O at 600 cm<sup>−1</sup>. The Nb<sub>2</sub>O<sub>5</sub>-NPs presented spherical morphology according to the SEM micrography with a specific surface area of 1.72 m<sup>2</sup> g<sup>−1</sup> and 36.31 nm pore diameter (isotherm type III) by the N<sub>2</sub> porosimetry. The pecan nutshell extract showed the presence of polyphenols (336.8 mgAG mL<sup>−1</sup>) and flavonoids (200.1 mgCt mL<sup>−1</sup>), demonstrating the high potential to act as a bioreducing and stabilizing agent for the green synthesis of Nb<sub>2</sub>O<sub>5</sub>-NPs. Therefore, the green synthesis of Nb<sub>2</sub>O<sub>5</sub>-NPs is feasible with potential application in different fields.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115106"},"PeriodicalIF":5.2,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}