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Al-modified yolk-shell silica particle-supported NiMo catalysts for ultradeep hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene:Efficient accessibility of active sites and suitable acidity

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Petroleum Science 2024年第1期21卷 654-666页

作者： Ke Yu Wei-Min Kong Zhen Zhao Ai-Jun Duan Lian Kong Xi-Long Wang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Institute of Catalysis for Energy and Environment College of Chemistry and Chemical EngineeringShenyang Normal UniversityShenyang 110034LiaoningChina

Yolk-shell SiO2 particles(YP)with center-radial meso-channels were fabricated through a simple and effective method.Al-containing YP-supported NiMo catalysts with different Al amounts(NiMo/AYP-x,x=Si/Al molar proportion)were prepared and dibenzothiophene(DBT)and 4,6-dimethyl-dibenzothiophene(4,6-DMDBT)were employed as the probes to evaluate the hydrodesulfurization(HDS)catalytic performance.The as-prepared AYP-x carriers and corresponding catalysts were characterized by some advanced characterizations to obtain deeper correlations between physicochemical properties and the HDS performance.The average pore sizes of series AYP-x supports are above 6.0 nm,which favors the mass transfer of organic sulfides.The cavity between the yolk and the shell is beneficial for the enrichment of S-containing compounds and the accessibility between reactants and active metals.Aluminum embedded into the silica framework could facilitate the formation of Lewis(L)and Brønsted(B)acid sites and adjust the metal-support interaction(MSI).Among all the as-synthesized catalysts,NiMo/AYP-20 catalyst shows the highest HDS activities.The improved HDS activity of NiMo/AYP-20 catalyst is attributed to the perfect combination of excellent structural properties of the yolk-shell mesoporous silica,enhanced acidity,moderate MSI,and good accessibility/dispersion of active components.

关键词： Al-containing yolk-shell silica particles Accessibility acidity Metal-support interaction Hydrodesulfurization

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Catalytic degradation of chlorinated volatile organic compounds(CVOCs)over Ce-Mn-Ti composite oxide catalysts

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Journal of Environmental Sciences 2024年第4期138卷 326-338页

作者： Zhiwei Zhou Qianqian Li Guijin Su Jiaxin Pang Bohua Sun Jing Meng Bin Shi Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450052China Key Laboratory of Environmental Nanotechnology and Health Effects State Key Laboratory of Environmental Chemistry and EcotoxicologyResearch Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds(CVOCs)in actual exhaust gasses.Here,commercial TiO_(2),typically used for molding catalysts,was chosen as the carrier to fabricate a series of Ce_(0.02)Mn_(0-0.24)TiO_(x) materials with different Mn doping ratios and employed for chlorobenzene(CB)destruction.The introduction of Mn remarkedly facilitated the synergistic effect of each element via the electron transfer processes:Ce^(3+)+Mn^(4+/3+)■Ce^(4+)+Mn^(3+/2+)and Mn^(4+/3+)+Ti^(4+)■Mn^(3+/2+)+Ti^(3+).These synergistic interactions in Ce_(0.02)Mn_(0.04-0.24)TiO_(x),especially Ce_(0.02)Mn_(0.16)TiO_(x),significantly elevated the active oxygen species,oxygen vacancies and redox properties,endowing the superior catalytic oxidation of CB.When the Mn doping amount increased to 0.24,a separate Mn_(3)O_(4) phase appeared,which in turn might weaken the synergistic effect.Furthermore,the acidity of Ce_(0.02)Mn_(0.04-0.24)TiO_(x) was decreased with the Mn doping,regulating the balance of redox property and acidity.Notably,Ce_(0.02)Mn_(0.16)TiO_(x) featured relatively abundant B-acid sites.Its coordinating redox ability and moderate acidity promoted the deep oxidation of CB and RCOOH-intermediates,as well as the rapid desorption of Cl species,thus obtaining sustainable reactivity.In comparison,CeTiO_(x) owned the strongest acidity,however,its poor redox property was not sufficient for the timely oxidative decomposition of the easier adsorbed CB,resulting in its rapid deactivation.This finding provides a promising strategy for the construction of efficient commercial molding catalysts to decompose the industrial-scale CVOCs.

关键词： Chlorobenzene Ce_(0.02)Mn_(0-0.2)4tiox materials Redox ability acidity Synergistic interaction

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Conversion of polyethylene to gasoline:Influence of porosity and acidity of zeolites

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Frontiers in Energy 2023年第6期17卷 763-774页

作者： Chunyu LI Haihong WU Ziyu CEN Wanying HAN Xinrui ZHENG Jianxin ZHAI Jiao XU Longfei LIN Mingyuan HE Buxing HAN Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200062China Beijing National Laboratory for Molecular Sciences CAS Laboratory of Colloid and Interface and ThermodynamicsCAS Research/Education Center for Excellence in Molecular SciencesCenter for Carbon Neutral ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China Institute of Eco-Chongming Shanghai 202162China

Plastic waste is causing serious environmental problems. Developing efficient, cheap and stable catalytic routes to convert plastic waste into valuable products is of great importance for sustainable development, but remains to be a challenging task. Zeolites are cheap and stable, but they are usually not efficient for plastic conversion at a low temperature. Herein a series of microporous and mesoporous zeolites were used to study the influence of porosity and acidity of zeolite on catalytic activity for plastics conversion. It was observed that H-Beta zeolite was an efficient catalyst for cracking high-density polyethylene to gasoline at 240℃, and the products were almost C_(4)–C_(12) alkanes. The effect of porosity and acidity on catalytic performance of zeolites was evaluated, which clearly visualized the good performance of H-Beta due to high surface area, large channel system, large amount accessible acidic sites. This study provides very useful information for designing zeolites for efficient conversion of plastics.

关键词： plastics conversion polyethylene zeolites acidity porosity

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Cyclic(Amino)(Aryl)Nitrenium Cations with Lewis acidity Controlled by Remote Substituents

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Chinese Journal of Chemistry 2022年第3期40卷 311-316页

作者： Wenqing Wang Xin Zheng Leran Zhang Shunjie Li Yue Zhao Xinping Wang College of Chemistry and Material Science Key Laboratory of Functional Molecular SolidsMinistry of EducationAnhui Laboratory of Molecule-Based MaterialsAnhui Normal UniversityWuhuAnhui 241002China State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjingJiangsu 210023China College of Science Henan Agricultural UniversityZhengzhouHenan 450002China

N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry.Stable cyclic(amino)(aryl)nitrenium cations,cyc-1^(+)-cyc-3^(+),were synthesized by chemical oxidation of aryl azo compounds with different substituents,H and I,at the para positions of the phenyl group.The excited triplet states of cyc-1^(+)-cyc-3^(+) abstract H-atoms step by step to generate radical intermediates cyc-1H^(*+-)cyc-3H^(*+)traced by EPR spectroscopy and products cyc-1H^(2+)-cyc-3H^(2+) characterized by single crystal X-ray diffraction.The Lewis acidity of species cyc-1^(+)-cyc-3^(+) are remote substituent-dependent.Cyc-2^(+)-cyc-3^(+) have much higher acidity than those previously reported congeners based on energies of LUMOs.The electrophilicity enables them to form Lewis adducts with neutral Lewis base Me_(3)P,and to gain one-electron to produce neutral radicals cyc-1^(*)-cyc-3^(*).

关键词： Nitrenium cation acidity Radicals Excited triplet state Electrophilicity

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Droplet microreactor for high-throughput fluorescence-based measurements of single catalyst particle acidity

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Microsystems & Nanoengineering 2023年第2期9卷 101-111页

作者： Jeroen C.Vollenbroek Anne-Eva Nieuwelink Johan G.Bomer Roald M.Tiggelar Albert van den Berg Bert M.Weckhuysen Mathieu Odijko BIOS Lab on a Chip Group MESA+InstituteUniversity of TwenteHallenweg 157522 NH EnschedeThe Netherlands inorganic Chemistry and Catalysis Debye Institute for Nanomaterials ScienceUtrecht UniversityUniversiteitsweg 993584 CG UtrechtThe Netherlands NanoLab Cleanroom MESA+InstituteUniversity of TwenteHallenweg 157522 NH EnschedeThe Netherlands

The particles of heterogeneous catalysts differ greatly in size,morphology,and most importantly,in activity.Studying these catalyst particles in batch typically results in ensemble averages,without any information at the level of individual catalyst particles.To date,the study of individual catalyst particles has been rewarding but is stll rather slow and often cumbersomel.Furthermore,these valuable in-depth studies at the single particle level lack statistical relevance.Here,we report the development of a droplet microreactor for high-throughput fluorescence-based measurements of the acidities of individual particles in fluid catalytic cracking(FCC)equilibrium catalysts(ECAT).This method combines systematic screening of single catalyst particles with statistical relevance.An oligomerization reaction of 4-methoxystyrene,catalyzed by the Bronsted acid sites inside the zeolite domains of the ECAT particles,Was performed on-chip at 95 ℃.The fluorescence signal generated by the reaction products inside the ECAT particles was detected near the outlet of the microreactor.The high-throughput acidity screening platform was capable of detecting~1000 catalyst particles at a rate of 1 catalyst particle every 2.4 s.The number of detected catalyst particles was representative of the overall catalyst particle population with a confidence level of 95%.The measured fluorescence intensities showed a clear acidity distribution among the catalyst particles,with the majority(96.1%)showing acidity levels belonging to old,deactivated catalyst particles and a minority(3.9%)exhibiting high acidity levels.The latter are potentially of high interest,as they reveal interesting new physicochemical properties indicating why the particles were still highly acidic and reactive.

关键词： catalyst acidity particle

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acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China

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Journal of Environmental Sciences 2006年第5期18卷 916-920页

作者： KUANG Yuan-wen ZHOU Guo-yi WEN Da-zhi LIU Shi-zhong Institute of Ecology South China Botanical Garden＇ Chinese Academy of Sciences Guangzhou 510650 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China

Barks of Pinus massoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution. The conductivities of the inner barks differed significantly among the three sites, with higher values at the clean site. However, the significant differences were not observed among these sites. Furthermore, the pH values for the inner and outer barks were not correlated with the conductivity, which did not coincide with some other studies.

关键词： acidity conductivity inner bark outer bark Pinus massoniana

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The balance of acidity and redox capability over modified CeO_2 catalyst for the selective catalytic reduction of NO with NH_3

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Journal of Environmental Sciences 2019年第5期31卷 273-279页

作者： Zhihua Lian Wenpo Shan Meng Wang Hong He Qingcai Feng Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion Institute of Urban Environment Chinese Academy of Sciences Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences

The effect of acidity and redox capability over sulfuric acid-modified CeO_2 catalysts were studied for the selective catalytic reduction of NO_x with NH_3(NH_3-SCR). The deposition of sulfate significantly enhanced the catalytic performance over CeO_2. NO_x conversion over4H_2SO_4/CeO_2 at 230–440 °C was higher than 90%. The strong redox capability of CeO_2 could result in unselective NH_3 oxidation and decrease high temperatures catalytic activity and N_2 selectivity. The deposition of sulfate increased the acidity and weakened the redox capability, and then increased the high temperature NO_x conversion and N_2 selectivity. An appropriate level of acidity also promoted the activity at 190–250 °C over ceria-based catalysts, and with further increase in the acidity, the SCR activity decreased slightly. Weak redox capability lowered the low-temperature catalytic activity. Excellent SCR activity requires a balance of acidity and redox capability on the catalysts.

关键词： NH3-SCR CeO2 acidity Redox capability H2SO4

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Reinvestigation of the Henry's law constant for hydrogen peroxide with temperature and acidity variation

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Journal of Environmental Sciences 2010年第4期22卷 570-574页

作者： Daoming Huang,Zhongming Chen The State Key Laboratory of Environmental Simulation and Pollution Control,College of Environmental Sciences and Engineering,Peking University,Beijing 100871,China. The State Key Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing 100871 China

Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx （OH and HO2） radicals and O3 in the atmosphere. Its partitioning between gas and aqueous phases in the atmosphere, usually described by its Henry＇s law constant （KH）, significantly influences its role in atmospheric processes. Large discrepancies between the KH values reported in previous work, however, have created uncertainty for atmospheric modelers. Based on our newly developed online instrumentation, we have re-determined the temperature and acidity dependence of KH for hydrogen peroxide at an air pressure of （0.960 ± 0.013） atm （1 atm = 1.01325 × 10^5 Pa）. The results indicated that the temperature dependence of KH for hydrogen peroxide fits to the Van＇t Hoff equation form, expressed as lnKH = a/T - b, and a = -△H/R, where KH is in M/atm （M is mol/L）, T is in degrees Kelvin, R is the ideal gas constant, and AH is the standard heat of solution. For acidity dependence, results demonstrated that the KH value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level （from pH 7 to pH 1）. Combining the dependence of both temperature and acidity, the obtained a and b were 7024 ± 138 and 11.97 ± 0.48, respectively, AH was （58.40 ± 1.15） kJ/（K.mol）, and the uncertainties represent σ. Our determined KH values for hydrogen peroxide will therefore be of great use in atmospheric models.

关键词： hydrogen peroxide Henry＇s law constant atmosphere acidity

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Gastric juice acidity in upper gastrointestinal diseases

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World Journal of Gastroenterology 2010年第43期16卷 5496-5501页

作者： Pei-Jung Lu Ping-I Hsu Chung-Hsuan Chen Michael Hsiao Hui-Hwa Tseng Kung-Hung Lin Seng-Kee Chuah Institute of Clinical Medicine National Cheng Kung University Division of Gastroenterology Department of Internal Medicine Kaohsiung Veterans General Hospital National Yang-Ming University Genomics Research Center Academic Sinica Department of Pathology Kaohsiung Veterans General Hospital and National Yang-Ming University Division of Gastroenterology Chang Gung Memorial Hospital Kaohsiung Medical Center College of Medicine Chang Gung University

AIM: To search the independent factors determining gastric juice acidity and to investigate the acidity of gastric juices in various benign and malignant upper gastrointestinal diseases. METHODS: Fasting gastric juice acidity of 165 healthysubjects and 346 patients with esophageal ulcer (n = 21), gastric ulcer (n = 136), duodenal ulcer (n = 100) or gastric cancer (n = 89) were measured and compared. Additionally, gastric specimens were taken from the antrum and body for rapid urease test and histological examination. RESULTS: Multivariate analysis revealed that bile stain of gastric juice, high acute inflammatory score of the corpus, and atrophy of the corpus were independent risk factors for the development of gastric hypoacidity with odds ratios of 3.1 (95% CI: 1.3-7.3), 3.1 (95% CI: 1.2-7.9) and 3.5 (95% CI: 1.3-9.2). Esophageal ulcer and duodenal ulcer patients had a lower pH level (1.9 and 2.1 vs 2.9, both P acidity existed in 22%, 5%, 29%, 5% and 88% of healthy subjects, esophageal ulcer, gastric ulcer, duodenal ulcer and gastric cancer patients, respectively. CONCLUSION: Bile reflux, atrophy and dense neutrophil infiltrate of the corpus are three independent factors determining the acidity of gastric juice.

关键词： acidity Gastric juice Gastric cancer Peptic ulcer Esophageal ulcer

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acidity effects of Hβ zeolite on olefin alkylation of thiophenic sulfur in gasoline

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Journal of Natural Gas Chemistry 2008年第1期17卷 45-50页

作者： Zekai Zhang Dong Liu Xiangxue Zhu Haiwei Yu Shenglin Liu Longya Xu State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 Liaoning China Dalian Petrochemical Corporations CNPC Dalian 116032 Liaoning China The Graduate University of Chinese Academy of Science Beijing 100049 China

Olefin alkylation of thiophenic sulfur process was carried out in model gasoline, using Hβ zeolites with different Si/Al2 ratios as catalysts. In particular, the influence of acid properties of Hβ zeolites on its catalytic ability for the thiophene alkylation, xylene alkylation and hexene oligomerization was investigated. The results showed that the acidity of the Hβ zeolite was increased with the decrease of Si/Al2 ratio, but its catalytic ability was not always increased. In fact, it reached the maximal catalytic ability at Si/Al2 ratio of 66, and under the reaction conditions of 60 ℃, 1.5 MPa, WHSV 3.0 h^-1 and time on stream 2 h. At the ratio, the conversion of thiophene, xylene, and oligomerized hexene were 96.6%, 2.7% and 2.8%, respectively. An optimal Si/Al2 ratio exists for the catalytic performance of Hβ zeolite. By investigating the coke deposition of the used Hβ zeolite catalysts, it has been found that the optimal Si/Al2 ratio is attributed to the combined effect of the carbocation activation capability and the hydrogen transformation capability of the Hβ zeolite catalyst.

关键词： desulfurization alkylation acidity Hβ gasoline

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