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Influence of surface acidity and chemical valence on low temperature activity over Pt-HSiW/CeO_(2) for catalytic combustion of chlorobenzene

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Journal of Rare Earths 2024年第9期42卷 1693-1703,I0002页

作者： Zhongxian Song Zepeng Liu Xuejun Zhang Yanli Mao Wei Liu Chunxiang Gao Haiyang Li Xia Zhang Changrui Han Zhenzhen Huang Key Laboratory of Carbon Emission Reduction and Combined Air Pollution Control Technology Faculty of Environmental and Municipal EngineeringHenan University of Urban ConstructionPingdingshan467036China College of Environmental and Safety Engineering Shenyang University of Chemical TechnologyShenyang110142China

Pt-HSiW/CeO_(2) catalysts were prepared for chlorobenzene(CB) catalytic combustion by hydrothermal method at different calcination temperatures,and the effects of the surface acidity and chemical valence on the catalytic activity were *** results show that the catalyst calcined at 450℃(Cat-B)exhibits the outstanding catalytic performance,and the Cat-B catalyst possesses 90% conversion of CB at148℃.The excellent catalytic activity of Cat-B is attributed to more Ce^(3+)/(Ce^(3+)+Ce^(4+)),Pt~0/(Pt^(0)+Pt^(2+)),O_(ads)/(O_(latt)+O_(ads)) and Lewis acid *** degradation mechanism is proposed based on the analysis of the intermediates with the following reaction pathway:chlorobenzene→phenates/benzoquinone→acetate→maleate→CO_(2)+H_(2)O.

关键词： Pt-HSiW/CeO_(2) Catalytic combustion Chlorobenzene acid sites Rare earths

Control of aluminum distribution in ZSM-5 zeolite for enhancement of its catalytic performance for propane aromatization

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FRONTIERS OF CHEMICAL SCIENCE AND ENGINEERING 2024年第8期18卷 86-0页

作者： Ma, Zhao Shi, Dezhi Wang, Sen Dong, Mei Fan, Weibin Chinese Acad Sci State Key Lab Coal Convers Inst Coal Chem Taiyuan 030001 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Regulation of aluminum distribution in zeolite framework is an effective method for improving its catalytic performance for propane aromatization. Herein, we found that recrystallization and post-realuminization of ZSM-5 cannot only create hollow structures to enhance the diffusion ability, but also adjust the content and position of paired aluminum species in its framework. Various characterizations results confirmed that increase of paired aluminum content and inducement of more aluminum atoms sited in the intersection cavity are beneficial to the formation of aromatic products in propane aromatization. As a result, the hollow-structured ZSM-5 zeolite with more paired aluminum (H-200-hollow) showed higher propane conversion and aromatics selectivity than other samples at the same conditions. The catalytic performance of H-200-hollow can be further improved by ion-exchanging with a small amount of Ga(III) species. The propane conversion and aromatics selectivity of Ga-200-hollow reached as high as 95% and 70%, respectively, at 540 degrees C and 1 atm.

关键词： propane aromatization zeolite aluminum distribution recrystallization and post-realuminization AL DISTRIBUTION REACTION PATHWAY acid sites FRAMEWORK METHANOL CONVERSION OLEFINS TEMPERATURE CRACKING STATE

Evolution mechanism of active sites for selective catalytic reduction of NO_(x) with NH_(3) over Fe-ZSM-5 catalysts doped by Ce/Cu

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Journal of Central South University 2022年第7期29卷 2239-2252页

作者： ZHANG Yu-bo WANG Pan YU Dan ZHAO Hong-yu LYU Xing-lei LEI Li-li School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang 212013China

Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_(x) with NH_(3).A variety of characterization techniques(NH_(3)-SCO,BET,XRD,XPS,UV-Vis,NH_(3)-TPD,H_(2)-TPR)were used to explore the changes of the active sites,acid sites and pore structure of the *** was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic *** Cu doping into the Fe-ZSM-5 catalyst produced new active species,isolated Cu ions and CuO particles,resulting in the improved low-temperature catalytic ***,the NH_(3) oxidation was enhanced,and part of the Fe^(3+)active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species,which causes the decrease of the high-temperature *** recovery of hightemperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species *** results provide theoretical support for adjusting the active window of Febased SCR catalyst by multi-metal doping.

关键词： Fe-based zeolite nitric oxide removal Cu/Ce modification active sites acid sites

Effect of silicon precursor on silicon incorporation in SAPO-11 and their catalytic performance for hydroisomerization of n-octane on Pt-based catalysts

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Journal of Energy Chemistry 2017年第4期26卷 688-694页

作者： Zhichao Yang Jilong Li Yunqi Liu Chenguang Liu State Key Laboratory of Heavy Oil Processing Key Laboratory of CatalysisChina National Petroleum Corp.(CNPC)China University of Petroleum(East China)Qingdao 266580ShandongChina

SAPO-11 molecular sieves were synthesized using silica sol, hydrophilic fumed silica, and tetraethyl orthosilicate（TEOS） as silicon precursors. Their physicochemical properties were characterized using XRD,SEM, nitrogen adsorption-desorption, Py-IR, NH;-TPD, EDS, and;Al,;P,;Si MAS NMR techniques. The catalytic performance was assessed in the hydroisomerization of n-octane. The results showed that the silicon precursors influenced the physicochemical properties and catalytic performance of SAPO-11. SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor showed higher silicon distribution and had more medium acid sites. SAPO-11 synthesized using TEOS as silicon precursor had more silicon content, but more silicon islands formed in its framework. The depolymerization of silicon precursors might affect the silicon content and distribution in SAPO-11. In the hydroisomerization of n-octane, the catalytic activity strongly depended on the number of medium acid sites instead of the number of total acid ***-11 synthesized using hydrophilic fumed silica as silicon precursor exhibited higher catalytic activity than the other samples because it has more medium acid sites.

关键词： SAPO-11 Silicon precursor Silicon incorporation acid sites Hydroisomerization n-Octane

Synergistic effects of Cu species and acidity of Cu-ZSM-5 on catalytic performance for selective catalytic oxidation of n-butylamine

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Journal of Environmental Sciences 2020年第10期32卷 55-63页

作者： Xin Xing Na Li Jie Cheng Yonggang Sun Zhongshen Zhang Xin Zhang Zhengping Hao Key Laboratory of Environmental Nanotechnology and Health Effects Research Center for Eco-Enuironmental SciencesChinese Academy of SciencesBeijing 100085China National Engineering Laboratory/or VOCs Pollution Control Material&Technology Research Center/or Environmental Material and Pollution Control TechnologyUniversity of Chinese Academy of SciencesBeijing 101408China

In this work, a series of Cu-ZSM-5 catalysts with different SiO2/Al2O3 ratios(25, 50, 100 and200) were synthesized and investigated in n-butylamine catalytic degradation. The n-butylamine can be completely catalytic degradation at 350 ℃ over all Cu-ZSM-5 catalysts. Moreover, Cu-ZSM-5(25) exhibited the highest selectivity to N2, exceeding 90% at 350 ℃. These samples were investigated in detail by several characterizations to illuminate the dependence of the catalytic performance on redox properties, Cu species, and acidity. The characterization results proved that the redox properties and chemisorption oxygen primarily affect n-butylamine conversion. N2 selectivity was impacted by the Bronsted acidity and the isolated Cu^2+ species. Meanwhile, the surface acid sites over Cu-ZSM-5 catalysts could influence the formation of Cu species. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra was adopted to explore the reaction mechanism. The Cu-ZSM-5 catalysts are the most prospective catalysts for nitrogen-containing volatile organic compounds removal, and the results in this study could provide new insights into catalysts design for VOC catalytic oxidation.

关键词： CH3CH2CH2CH2NH2 Selective oxidation Cu-ZSM-5 Cu species acid sites

Chemical deactivation of V2Os-WO3/Ti02 SCR catalyst by combined effect of potassium and chloride

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Frontiers of Environmental Science & Engineering 2013年第3期7卷 420-427页

作者： Xiaodong WU Wenchao YU Zhichun SI Duan WENG State Key Laboratory of New Ceramics & Fine Process Department of Materials Science and Engineering Tsinghua University Beijing 100084 China Advanced Materials Institute Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China Yangtze Delta Region Institute of Tsinghua University Jiaxing 314000 China

V2O5-WO3/WiO2 catalyst was poisoned by impregnation with NHaC1, KOH and KC1 solution, respectively. The catalysts were characterized by X-ray diffraction （XRD）, inductively coupled plasma （ICP）, N2 physisorption, Raman, UV-vis, NH3 adsorption, temperature-programmed reduction of hydrogen （H2- TPR）, temperature-programmed oxidation of ammonia （NH3-TPO） and selective catalytic reduction of NOx with ammonia （NH3-SCR）. The deactivation effects of poison- ing agents follow the sequence of KC1 〉 KOH 〉〉 NH4CI. The addition of ammonia chloride enlarges the pore size of the titania support, and promotes the formation of highly dispersed V = O vanadyl which improves the oxidation of ammonia and the high-temperature SCR activity. K~ ions are suggested to interact with vanadium and tungsten species chemically, resulting in a poor redox property of catalyst. More importantly, potassium can reduce the Bronsted acidity of catalysts and decrease the stability of Bronsted acid sites significantly. The more severe deactivation of the KCl-treated catalyst can be mainly ascribed to the higher amount of potassium resided on catalyst.

关键词： V2Os-WO3/TiO2 potassium chloride poison-ing reducibility acid sites

Effects of cerium and vanadium on the activity and selectivity of MnO_x-TiO_2 catalyst for low-temperature NH_3-SCR

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Journal of Rare Earths 2011年第1期29卷 64-68页

作者：吴晓东司知蠢栗国翁端马子然 State Key Laboratory of New Ceramics & Fine Process Department of Materials Science and EngineeringTsinghua University

MnOx-TiO2, CeO2-MnOx-TiO2 and V2O5-MnOx-TiO2 catalysts for low-temperature NH3-SCR were prepared by sol-gel method. The results showed that both cerium and vanadium prevented the transformation ofanatase TiO2 to the mille phase. The addition of vanadium oxide induced the segregation of crystalline Mn2O3, which contributed little to low-temperature SCR and ammonia oxidation, from the MnOx-TiO2 solid solutions. However, the selectivity of the V-containing catalyst was almost 100% due to the decreased ammonia consumption and enhanced adsorption capacity of ammonia on Bronsted acid sites at relatively high temperatures. The electron-donating effect of cerium reduced the Mn^4＋/Mn^3- ratio to some extent, resulting in a decreased activity for ammonia oxidation. This, in combination with the enhanced ammonia adsorption capacity by Ce^n＋ as additional Lewis acid sites, endowed the Ce-doped catalyst a higher N2 selectivity than MnOx-TiO2 despite the slightly elevated light-offtemperamre for NO conversion.

关键词： MnOx-TiO2 modification selective reduction of NO acid sites rare earths

Praseodymium Oxide Modified CeO2/Al2O3 Catalyst for Selective Catalytic Reduction of NO by NH3

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Chinese Journal of Chemistry 2016年第12期34卷 1283-1290页

作者： Qijie Jin Yuesong Shen Shemin Zhu College of Materials Science and Engineering Nanjing Tech University Nanjing Jiangsu 210009 China Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites Nanjing Tech University Nanjing Jiangsu 210009 China Jiangsu National Synergetic Innovation Center for Advanced Materials Nanjing Tech University Nanjing Jiangsu 210009 China

A series of CeO2/Al2O3 catalysts was modified with praseodymium oxide using an extrusion method. The cata- lytic activities of the obtained catalysts were measured for the selective catalytic reduction of NO with NH3 to screen suitable addition of praseodymium oxide. These samples were characterized by XRD, N2-BET, NH3-TPD, NO-TPD, Py-IR, H2-TPR, Raman spectra and XPS, respectively. Results showed the optimal catalyst with the Pr/Ce molar ratio of 0.10 exhibited more than 90% NO conversion in a wide temperature range of 290-425℃ under GHSV of 5000 h i. The number of Lewis acid sites and the chemisorbed oxygen concentration of the catalysts would increase with the Pr incorporation, which was favorable for the excellent catalytic performance. In addition, the Pr incorporation inhibited growth of the Al2O3 crystal particles and led to the lattice expansion of CeO2, which increased catalytic activity. The results implied that the higher chemisorbed oxygen concentrations and the more Lewis acid sites were conductive to obtain the excellent SCR activity.

关键词： CeO2/A1203 catalytic performance acid sites selective catalytic reduction

Influence of morphology of hollow silica-alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane

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Journal of Advanced Ceramics 2017年第4期6卷 368-375页

作者： Naoki TOYAMA Ryota OGAWA Haruki INOUE Shinobu OHKI Masataka TANSHO Tadashi SHIMIZU Tetsuo UMEGAKI Yoshiyuki KOJIMA Department of Materials&Applied Chemistry College of Science&EngineeringNihon University1-8-14Kanda-SurugadaiChiyoda-KuTokyo 101-8308Japan National Institute for Materials Science 3-13SakuraTsukubaIbaraki 305-0003Japan

Hollow silica-alumina composite spheres were prepared by a polystyrene(PS)template method using various amounts of PS *** hollow spheres prepared using 40 g were found to be with a diameter of about 300 nm in scanning electron microscopy,and transmission electron microscopy demonstrated their hollow sphere *** the nitrogen adsorption isotherm results,the homogeneous hollow spheres prepared using 40 g of the PS suspension were found to be an ordered pore *** activities of the hollow spheres prepared using various amounts of the PS suspension for hydrolytic dehydrogenation of ammonia borane were *** results showed that 10,7,and 6 mL of hydrogen were evolved from the aqueous ammonia borane solution in about 40 min in the presence of the hollow spheres prepared using 40,80,and 120 g of PS suspension,*** homogeneous hollow spheres with an ordered pore structure showed the highest activity among all the hollow *** amount of acid sites and the coordination number of aluminum active species were characterized using neutralization titration and solid-state ^(27)Al magic angle spinning nuclear magnetic resonance *** homogeneous hollow spheres with an ordered pore structure had high amount of acid sites and 4-coordinated aluminum *** relative proportion of 4-coordinated aluminum species was related to the dispersion of aluminum *** results indicate that the homogeneous hollow spheres with an ordered pore structure showed the high activity because of high amount of acid sites induced by the highly dispersed aluminum species.

关键词： ammonia borane morphology hollow silica-alumina composite spheres dispersion acid sites