APPLIED CATALYSIS B-ENVIRONMENTAL
·
2013
·
IF 5.825
Chunyu Chen,Jie Zhu,Fang Chen,Xiangju Meng,Xiaoming Zheng,Xionghou Gao,Feng-Shou Xiao
Removal of volatile organic compounds (VOCs) has recently been attracted much attention, and catalytic combustion is one of good methods for solving this problem. In this research, we show a successful preparation of mesoporous Beta zeolite-supported Pt catalyst (Pt–R/Beta-H) and its superior performance in the catalytic combustion of toluene. N 2 sorption isotherms show that the mesopore volume of Pt–R/Beta-H reaches 0.18 cm 3 /g, and TEM images exhibit that the Pt particles exist in both micropores and mesopores of the sample. Interestingly, the Pt particles on Pt–R/Beta-H have higher dispersion than the Pt particles on conventional Beta zeolite (Pt–R/Beta). XPS spectra also reveal that Pt–R/Beta-H has higher Pt 0 /Pt 2+ ratio than Pt–R/Beta. Very importantly, Pt–R/Beta-H exhibits much higher catalytic activities and longer catalyst life as well as lower apparent activation energy in the catalytic combustion of toluene than Pt–R/Beta. The extraordinary performance in the catalytic combustion of toluene over Pt–R/Beta-H catalyst is of great importance for obtaining clean environment and enhancing human health.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
2021
·Vol. 29
·期 2
·371-380
·
IF 2.496
Zhang Wei,Xue Haonan,Wang Min,Wu Zeying,Ding Linlin,Deng Yaoyao,Wang Wei,Wei Xuejiao,Zhang Zhenwei,Xiang Mei
Cu-containing Beta zeolites (Cu-Beta) are straightforwardly synthesized in a one-pot method without template, where the crucial step is the co-hydrolysis/condensation of silica source and copper salt at the moderate acidic condition. In the solvent-free oxidation of cyclohexane with molecular oxygen (O 2 ), the best cyclohexane conversion result (9.7%) with a KA-oil (cyclohexanone and cyclohexanol) selectivity of 94.1% is obtained over Cu-Beta(100). Structure—activity relationship analysis indicates that the isolated tetrahedral framework Cu 2+ species and chemisorption oxygen species in high concentration on the catalyst surface enhannce the catalic performance. In addition, the catalyst can be easily separated and still remain stable after recycling five times, providing new insights into catalysts design for the catalytic oxidation of cyclohexane to KA-oil.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yu Wang,Hang Zhang,Dingmei Han,Meiyu Liu,Binbin He,Yun Zu
Cobalt (Co)-based zeolite catalysts are promising alternatives to replace expensive Pt- and toxic Cr-based catalysts for direct propane dehydrogenation (PDH). However, identifying the interaction between Co species and surface Si-hydroxyls of siliceous zeolites has been an inevitable challenge to realize the controllable construction of the Co species as dehydrogenation sites. Herein, we have fabricated a series of Co/Si-Beta(m-n) catalysts by using the dealuminated Si-Beta zeolites with “on-purpose” quantifying different type of Si-hydroxyls, involving geminal silanols ( g -SiOH), vicinal silanols ( v -SiOH) and silanol nests ( n -SiOH). In comparison to ultra-small CoO x nanoparticles (< 1.0 nm) directly trapped by the n -SiOH structure, a moderate interaction was built between tetrahedrally-coordinated divalent CoO x nanoparticles (∼4.5 nm) and external n -SiOH structure, resulting from partial migration and aggregation of initial CoO x species preferentially captured with g -/ v -SiOH structures during H 2 reduction. Given this, a representative Co/Si-Beta(500–12) catalyst exhibited a high catalyst productivity of 29.22 mol/g-catalyst (the product of initial reaction rate and the inverse of deactivation coefficient) with about 96 % propylene selectivity. In-situ FTIR spectra further revealed that such superior PDH performance was attributable to the moderately interaction of defined Si-O-Co structure that could be conducive to form the 2-propyl intermediate product, supporting the production of propylene and H 2 . These findings provide a novel inspiration for the development and optimization of low-cost, ecofriendly and advanced PDH catalysts.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2019
·
IF 0
Limei Cao,Qian Wang,Ji Yang
A novel ultrafine Pt/Beta catalyst supported on carbon paper was prepared and applied to selective catalytic reduction of NO x by H 2 at a low temperature below 90 °C. Here, 0.8 wt.% Pt/Beta reached approximately 100 % NO conversion at 90 °C under oxygen-rich conditions (1000 ppm NO, 1 % H 2 , and 4 % O 2 ). The influence of the dispersion and particle size of Pt on the catalytic performance was investigated using Polyvinylpyrrolidone (PVP) as a structure directing agent to regulate the Pt particles. The feeding amount of PVP significantly influenced the catalytic activity of the catalysts. When the feeding amount was less than 50 mg, the Pt particle size was smaller, and the dispersion was higher, providing a higher NO conversion. However, when the feeding amount exceeded 50 mg, the dispersion no longer increased, and the activity slightly decreased. N 2 physisorption (BET) confirmed that excessive PVP decreased the specific surface area, which suppressed the catalytic activity of Pt/Beta. Moreover, the NO conversion efficiency was dependent on the dispersion and particle size of Pt and was minimally affected by the surface area of the catalysts. The Pt/Beta catalyst system was deactivated, and an irreversible poisoning phenomenon for SO 2 was observed. Zr, Ce, and V were introduced into the catalyst system as metal auxiliaries . The Ce-modified Pt-Ce/Beta catalyst prepared in this study showed resistance to SO 2 .
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
JOURNAL OF CATALYSIS
·
2023
·
IF 7.3
Zijun Yang,Qiang Yu,Hua Wang,Qingfeng Ge,Xinli Zhu
Ketonization of propionic acid has been investigated on Lewis acidic TS-1 and Ti-Beta zeolites to understand the reaction mechanism and effects of pore topology and hydrophobicity. Characterizations showed that TS-1 and Ti-Beta (Si/Ti = 40) exhibited a similar acidity whereas TS-1 was more hydrophobic than the silanol-rich Ti-Beta. TS-1 showed higher activity, selectivity, stability and was more resistance to H 2 O than Ti-Beta. A combination of infrared spectroscopic, isotopic and kinetic studies showed that the molecularly adsorbed monodentate propionic acid is the most abundant reactive intermediate, and C-C coupling is the rate-determining step. The mechanism of ketonization of propionic acid at isolated tetrahedral Ti centers can be described by a Langmuir-Hinshelwood model. The turnover rate on TS-1-40 is ∼ 1.3 times higher than that on Ti-Beta-40, which is consistent with the lower fitted free activation energy, i.e., the energy difference between C-C coupling transition state and two co-adsorbed propionic acids at a Ti center. The slightly lower activation enthalpy on Ti-Beta-40 than TS-1-40 is over-compensated by much larger entropy penalty, due to more silanol groups and hydrogen bonded propionic acids in close proximity to the Ti center for Ti-Beta-40, which impose additional steric hindrance to bulkier C-C coupling complex at transition state and outweigh the difference of steric hindrance of pore confinement between MFI and BEA frameworks. This work provides insight into the ketonization mechanism on Lewis acidic zeolites, and indicates that moderate pore size with hydrophobic property promotes ketonization of carboxylic acid at isolated tetrahedral Ti centers confined in zeolites.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
RENEWABLE ENERGY
·
2024
·
IF 9
Yanchao Liu,Weijiong Dai,Lichen Zhang,Jiajun Zheng,Yanze Du,Xiwen Zhang,Tong Zhang,Bo Qin,Ruifeng Li
The conversion of waste cooking oil into biodiesel can bring about dual benefits: alleviating environmental pollution and realizing waste recycle. Embryonic zeolite has highly accessible acid sites because of the partially formed or more open zeolitic structure, which can solve problems such as diffusion limitation and inaccessible acid sites that the traditional zeolite catalysts face in the process of macromolecular reactants. In this work, a series of embryonic Beta zeolites were prepared by using mesoporous SBA-15 as a self-sacrificial silica source via a solid-state transformation strategy. NH 3 -TPD and FT-IR pyridine adsorption confirm that Brønsted acid sites have been created in these amorphous form embryonic catalysts. The diffusion property of toluene obtained by a zero-length column method proved that the higher the zeolization degree, the greater the diffusion activation energy. The synergistic effects resulted from the combination of the ordered mesoporous structures (ranging from 2 to 10 nm) stemming from the SBA-15 substrate and the moderate acid sites (∼88 μmol g −1 ) offered the embryonic SBEA-3 catalyst with remarkable catalytic performance for ≥95 % conversion during 20 times cycling tests and more than 90 % methyloleate yield.
研究领域:
化学工程
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环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Zhibo Xu,Fumin Wang,Xubin Zhang,Yi Zhai,Linfang Jiang,Kaiwei Wang,Yongwang Li,Qing Zhang
To enhance the doping of vanadium in zeolites and achieve high stability, the selection of vanadium precursors containing specific vanadium species can effectively overcome this crucial problem. Two series of V x Si-Beta(A) and V x Si-Beta(N) zeolites have been prepared by a two-step post-synthesis method at pH = 1 and pH = 7. The properties and environments of vanadium in samples are investigated by UV–vis, XPS, EPR, H 2 -TPR and 51 V MAS NMR. The bonding between vanadium and framework in VSi-Beta(A) is stronger than that of VSi-Beta(N). After the two are calcined or hydrated, the vanadium species in the former are relatively stable, while the pseudo-tetrahedral V(V) species and pseudo-octahedral V(V) species in the latter are interconverted. The changes of vanadium species in the supernatant during the preparation have been investigated by 51 V static NMR. At low concentration and pH = 1, there is a unique mononuclear cation (VO 2 + ) in the aqueous NH 4 VO 3 solution, which is favorable for the interaction with the negatively charged hydroxyl nests generated after the nitric acid dealumination , and enables the V atoms to be tightly inserted into the framework. In styrene epoxidation, the type of V(V) species in the catalyst could significantly affect its catalytic performance, and the catalytic activity and stability of V x Si-Beta(A) are superior than that of V x Si-Beta(N).
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2025
·
IF 3.9
Yunqi Hu,Chenyang Zhao,Zhaojun Liu,Honghai Liu,Hongjuan Zhao,Xinye Fan,Gen Li,Hong Meng,Hongtao Liu
Beta zeolite with micromesoporosity showed great application potential due to its hierarchical structure. However, this type of hierarchical zeolite was usually prepared in the presence of both an organic microtemplate and a meso-template, which limited its widespread application. In this investigation, a simple and entirely inorganic procedure to manipulate the micromesopore structure was reported. Herein, microporosity was induced by the presence of crystal seeds (CS), and mesoporosity was obtained via the introduction of potassium carbonate. The comprehensive characterization results exhibited that the obtained materials featured a high degree of crystallization and a much-enhanced mesoporosity structure (surface area of mesopores: 121.3 m2·g–1 and mesoporosity volume: 0.15 cm3·g–1). Moreover, this novel material showed greatly improved catalytic cracking properties toward heavy oil.
研究领域:
材料科学
·
化学工程
·
催化
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Zhen Liu,Hu Li,Yi Wang,Yu Wang,Peng Peng,Xinmei Liu
Due to higher thermal and hydrothermal stability, suitable acidity properties, Beta zeolite is considered as promising catalyst for naphtha catalytic cracking process. However, high cost and environmental pollution issue limit its industrial application by using high content of N-containing organic structural directing agent (SDA). In this paper, different SiO 2 /Al 2 O 3 ratios of Beta zeolites were prepared assisting by seeds induced method with low SDA and cheap industrial silica sol as the silicon source. Physical and chemical properties of as-prepared Beta zeolites were characterized by XRD, N 2 adsorption-desorption, NH 3 -TPD, Py-FTIR and SEM. N-Heptane was used as model compound for catalytic cracking performance evaluation. The results showed that Beta zeolite with high SAR was successfully synthesized, which had well defined crystallinity, proper specific surface area and pore structure, high B/L ratio and strong acid site. n-Heptane catalytic cracking performance showed high yield of low-carbon olefins with relative low activity on hydrogen transfer reaction and coke formation.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2022
·Vol. 2022
·期 16
·e202200130
·
IF 2.551
Shengqiang Zhou,Lipeng Zhou,Yunlai Su,Xiaomei Yang,Hao He
Graphical Sn-Beta was synthesized by a quasi-solid-phase method without adding additional solvent. Low amount of template and mineralizer was used as compared with traditional route. Sn-Beta zeolites were successfully synthesized through a quasi-solid-phase method by grinding the raw materials and then crystallizing in solid state. The method employed small amount of tetraethyl ammonium hydroxide (TEAOH) and no additional solvent, except for the water contained in template solution. The synthesis conditions including amount of TEAOH and water, and crystallization time were explored. Under optimized conditions, the obtained sample showed high crystallinity and capped square bipyramidal crystals. The diffuse reflectance ultraviolet-visible spectra and Fourier transform infrared spectra of CD 3 CN and pyridine adsorption were used to characterize the state of Sn and acidity in Sn-Beta sample. Sn 4+ ions were introduced into the framework which generated strong Lewis acid sites. The sample synthesized by quasi-solid-phase method gave 38.5 % methyl lactate (MLA) yield for the conversion of glucose to MLA, which is comparable to that of Sn-Beta prepared with conventional hydrothermal method (39.4 %).
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Guang Xiong,Xiyan Liu,Ruixue Zhao,Jiaxu Liu,Jinpeng Yin,Qingrun Meng,Zhendong Guo,Liping Liu
Nano-sized zeolite Beta aggregates with interparticle mesopores were synthesized by the aerosol-assisted method. The amorphous powders in the Na 2 O–Al 2 O 3 −SiO 2 system, which was obtained from an aerosol drying process, were used as the precursor. The zeolite was crystallized in a high concentration system with high alkalinity. This can not only improve the autoclave utilization and the crystallization rate, but also reduce the amount of both template and waste water. The obtained zeolite Beta is spherical nano-aggregates with interparticle mesopores. It shows high BET surface area and good Al species distribution. The study on crystallization process indicated that the precursor gradually dissolved under the strong alkaline condition and the nano-sized zeolite crystals were formed in the liquid phase as time prolonged. Therefore, the transformation mechanism mainly followed the liquid-phase mechanism. More importantly, the zeolite beta synthesized by aerosol-assisted method exhibited good catalytic activity and stability in the cracking reaction of 1,3,5-TIPB.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2021
·
IF 7.963
Meng Xia,Zheng Shen,Minyan Gu,Wenbo Chen,Wenjie Dong,Yalei Zhang
Microalgae residue was efficiently converted into lactic acid with a high yield (33.9%) under mild reaction conditions (210 °C, 2 h) over a Fe-Sn-Beta catalyst. Under the action of homogeneous H 3 O + and distinct Lewis acid sites on the catalyst, the production of lactic acid from microalgae residue underwent three main reaction steps: hydrolysis, isomerization , and retro-aldol condensation. Results demonstrated that the lipid component had a strong inhibitory effect on the production of lactic acid due to the formation of aromatics, esters, and complex nitrogenous heterocyclic compounds , which covered or poisoned the Lewis acid sites of the catalyst. The protein component acted as a chemical buffer that enhanced the production of lactic acid by controlling the release of monosaccharides from the carbohydrate fraction of microalgae and maintaining the catalytic activity of the catalyst. Thus, microalgae residue demonstrated great promise for the production of value-added chemicals.
研究领域:
生物化学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）