APPLIED CATALYSIS A-GENERAL
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2021
·
IF 5.706
Juan Ye,Chenyu Chen,Ying Zheng,Dan Zhou,Yunzhen Liu,Denglong Chen,Liufang Ni,Gang Xu,Fanan Wang
The selective one-pot synthesis of lactic acid (LA) from cellulose, and further the raw biomass, on heterogeneous catalysts is the key point for the development of biorefinery technology. Herein, we reported an yttrium (Y) modified siliceous Beta zeolites catalyst via two-step post-synthesis for highly efficient conversion of cellulose to LA. Under condition of 220 °C and 2 MPa N 2 , the cellulose could be transformed to LA with a yield of 49.2 % within 30 min, and the substrate can be extended to various raw biomass. It was demonstrated that the dealumination and modification of Y can efficiently modulate the acidity on the surface of zeolite. The dehydration products HMF and other derivatives were suppressed, and the yield of LA was correlated in line with the acid amount, which were attributed to the increased Lewis acidity originated by Y incorporation. These results contribute to the development of the green and efficient synthesis of bio-chemicals.
研究领域:
生物化学
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催化化学
·
可再生资源
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2022
·
IF 4.778
Xiaomei Yang,Xu Chen,Bin Lv,Yunlai Su,Lipeng Zhou
Sn-Beta zeolite is an excellent catalyst for the transformation of biomass derived carbohydrates. However, the long synthesis time restricted its application. Here, alkaline (earth) salt was used as promoter to accelerate the crystallization of Sn-Beta. Different alkaline (earth) salts and the amount of MgCl 2 were investigated. The properties of the synthesized samples were characterized by various techniques and compared with Sn-Beta, and the catalytic performance was investigated for the conversion of glucose to methyl lactate (MLA). The results indicate that a small amount of alkaline (earth) salt, especially MgCl 2 , promoted dramatically the crystallization of Sn-Beta. The full crystallization time was shortened from 15 d to 5 d with the aid of MgCl 2 ( n Mg / n Sn of 1.0) for Sn-Beta with n Si / n Sn of 100. Sn 4+ cations were incorporated into the framework sites, while Mg 2+ cations replaced the protons of silanol defects. Mg–Sn-Beta with strong Lewis acid sites and less silanols showed high activity and selectivity for glucose conversion to MLA. The yield of MLA is 20% over the fully crystallized Sn-Beta at 120 °C for 15 h and glucose concentration of 3.1 wt%, which increased significantly to 44% over the fully crystallized 1 Mg–Sn-Beta. Furthermore, Mg–Sn-Beta is stable and recyclable.
研究领域:
催化化学
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生物质转化
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 12
·期 2
·652-663
·
IF 6.119
Chuanyu Yang,Zhongwen Dong,Weifeng Chu,Yanan Wang,Dongpu Zhao,Fucun Chen,Wenjie Xin,Xiangxue Zhu,Shenglin Liu,Longya Xu
A series of beta zeolite catalysts with controllable particle sizes and similar Si/Al ratios were prepared by introducing imidazole (IMD) into the synthesis system and used for liquid-phase transalkylation of diethylbenzene (DEB) with benzene (Bz). The beta zeolite catalyst prepared with an IMD/SiO2 molar ratio of 0.5 possessed the smallest particle size (mean particle size of 119 nm) and the highest DEB conversion of 79.16% under the reaction conditions: 260 °C, 4.0 MPa, WHSV (diethylbenzene) of 2.0 h−1, W(benzene)/W(diethylbenzene) of 3/1, time on stream of 5 h. Then, to elucidate the catalytic roles of acid sites with different strengths, types and positions in beta zeolite in the transalkylation reaction, we carried out Na+ loading on the prepared beta zeolite to eliminate strong acid sites and poisoned the Brønsted acid sites and external acid sites by using 2,4-dimethylquinoline (2,4-DMQ) and triphenylphosphorus (TPP) as toxic reagents, respectively. The results suggested that the moderate and strong Brønsted acid sites of beta-IMD0.5 were the active sites for the liquid-phase transalkylation of DEB with Bz and their utilization rate showed a trend of increasing first and then decreasing. Significantly, 31% of the external Brønsted acid sites of beta-IMD0.5 contributed 81% of DEB conversion. The external acid sites had more contribution to the reaction due to the short diffusion path and fine accessibility.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
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IF 4.9
Weimin Zhang,Wenming Hao,Yanni Guo,Jinghong Ma,Ruifeng Li
Even though cetyltrimethylammonium bromide (CTAB) has been successfully used in the surfactant-templating system to create the mesostructured zeolites , the formation mechanism of the pore structure still remains elusive. Here, we investigated the sol-gel and structure evolution in the hierarchical zeolite Beta synthesis focusing on the role of CTAB in a dual templating system. It is found that the induction period was prolonged and the Ostwald ripening was retarded by the presence of CTAB in crystallization . CTAB was involved in the synthesis and incorporated within the solid phase at the first stage when mesopores were formed. However, the incorporated CTAB was released later into the solution when the crystallized microporous structure was developed. The thermogravimetric analysis revealed that CTA + cation worked both as structure directing agent (SDA) for micropores and mesoporogen for the secondary lager pores in the matrix of hierarchical zeolite Beta. Moreover, CTA + competed with tetraethylammonium cation (TEA + ) to work as the SDA for micropores, with a decrease of the total amount of CTA + and TEA + when the concentration of CTAB in the synthesis solution was increased. It is anticipated that the understanding of the role of CTAB in the sol-gel and structure evolution in the hierarchical zeolite Beta synthesis process can provide a basis for designing the synthesis of hierarchical zeolites.
研究领域:
化学工程
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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
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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
Xiaolong Liu,Jiaxing Zhang,Xue Liu,Kaixuan Yang,Ting Su,Hongying Lü,Peng Wu,Zhiguo Zhu
Catalytic conversions of cyclic ketones into lactones by the Baeyer–Villiger oxidation are particularly attractive for practical applications because catalytic transformations minimize reactant use as well as waste production while simplify processing conditions. Understanding the unique behaviors of highly mesoporous Sn-Beta zeolite catalyst during Baeyer–Villiger oxidation is a challenging research topic. Herein, highly mesopore single-crystalline Sn-Beta zeolite (Sn-Beta-2s) is hydrothermally synthesized via our developed two-step interzeolite transformation strategy. The synthesis mechanism obeys dissolution–recrystallization process, where the degradation step is essential to prepare Sn-Beta-2s zeolite with abundant mesoporous and relatively high hydrophobicity. This single-crystalline Sn-Beta zeolite is adopted to the Baeyer-Villiger oxidation of cyclic ketones as heterogeneous Lewis acid catalyst. Structure-performance relationship reveals that the diffusion performance dominates the product selectivity over three Sn-Beta zeolites. Through the investigation of catalytic mechanism by in-situ FT-IR spectra and DFT calculations, it is found that carbonyl group is activated by zeolitic framework Sn. As for the bulky tert -butyl hydroperoxide oxidant, the reaction can be only triggered on the zeolite surface due to the severe steric constraints within zeolite channels, accounting for the excellent catalytic activity of Sn-Beta-2s zeolite with nanocrystalline nature.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 10
·869
·
IF 3.444
Xinyu Liu,Meihuan Lu,Xuan Wang,Juyou Lu,Jianxin Yang
For decades the steric effect was still ambiguously understood in catalytic benzylation reactions of arenes with benzyl alcohol, which limited the green synthesis of phenylmethane derivates in industrial scale. This research applies a series of silica–alumina beta zeolites to systematically evaluate factors like catalyst porosity, reactants molecule size, and reaction temperature on catalytic benzylation. First, a suitable hierarchical beta zeolite catalyst was screened out by X-ray powder diffraction, N2adsorption−desorption, and probe benzylation withp-xylene. In the following substrates expanding study, for a typical benzylation of benzene, it showed extraordinary performance among literature reported ones that the conversion was 98% while selectivity was 90% at 353 K only after 10 min. The steric effect of aromatics with different molecular sizes on benzylation was observed. The reaction activities of four different aromatics followed the order: benzene > toluene >p-xylene > mesitylene. Combined with macroscopic kinetic analysis, this comprehensive study points out for the first time that the nature of this steric effect was dominated by the relative adsorption efficiency of different guest aromatic molecules on the host zeolite surface.Keywords:benzylation;benzyl alcohol;hierarchical zeolite;steric effect;green catalysis
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
ACS Applied Nano Materials
·
2024
·
IF 5.3
Jiwen Si,Ruifeng Guo,Fagui Qiu,Weikun Ning,Yanbin Sun,Wenqing Li,Qinglong Tao,Shiding Miao
The nanosize Beta-zeolites with hierarchical structures were time efficiently synthesized from natural diatomite and ball clays under 150 °C via a vapor-assisted method with the absence of solvents and F– anions. The Sn(IV) species were incorporated within frameworks of the presynthesized Beta-zeolite using a modified treatment of acid and tetraethylammonium hydroxide (TEAOH). The dealumination and reconstruction of zeolite frameworks were essential. A high atomic ratio of Si/Sn = 63.95 was obtained and the Sn(IV) species were in a tetrahedral coordination in the zeolite framework, as confirmed by various characterizations. The Sn-Beta zeolites show excellent performance in the Baeyer–Villiger oxidation reaction for the conversion of cyclohexanone to ε-caprolactone, with 63.3% conversion of cyclohexanone and superior selectivity for ε-caprolactone. The durability and stability of the catalyst was acceptable, as evidenced by a slight decrease in conversion of only 2.5% after 5 catalytic runs. These demonstrated a prototype practice in synthesizing Sn-Beta zeolites from natural ores and applicable catalysis in green chemistry.
研究领域:
材料科学
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催化化学
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绿色化学
✓ 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
·
2024
·
IF 4.8
Wenfeng Hao,Peng Lu,Xiaosheng Wang,Yuxiang Liu
A simple and facile co-calcination strategy of Beta molecular sieves and cerous nitrate is proposed. Based on the results of XRD , UV–Vis, in-situ FTIR, and 29 Si MAS NMR techniques, open-site configurations of Ce(III)O 4 and Ce(IV)O 4 tetrahedrons are observed due to a large ionic radius of Ce 3+ and Ce 4+ ions. Open-site configurations result in a low ratio of BrØnsted and Lewis acid sites in HBeta-Ce-6. In the isomerization of α- pinene, a higher amount of Lewis acid sites increases the yield for camphene . BrØnsted acids are accessible for α- pinene to form limonene due to a high surface area and low coke deposition. Isomorphous incorporation of Ce 3+ occurs and a decreasing selectivity for limonene are observed using regenerated catalysts. These results indicate that co-calcination strategy protects Beta molecular sieves from thermal destruction, endows Beta molecular sieves with a higher relative crystallinity and porosity during calcination .
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
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
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Sustainable Energy & Fuels
·
2020
·Vol. 4
·期 10
·5327-5338
·
IF 5.503
Meng Xia,Wenjie Dong,Zheng Shen,Shaoze Xiao,Wenbo Chen,Minyan Gu,Yalei Zhang
In the catalytic transformation of biomass into valuable chemicals, it is extremely important to inhibit undesirable reactions to increase the yield of target products. In this study, the introduction of indium and tin into Beta zeolites promoted the transformation of glucose into lactic acid with a high yield of 53%. Selective experiments and a developed kinetic model confirmed the sensitivity of the main reaction rate to the action of tin, including those of the isomerization and retro-aldol condensation reactions, and shielding of the side reactions by indium. An in-depth analysis of the catalyst acidity showed that weak Lewis acidity in the indium and tin species promoted the main reaction steps, whereas the decreased amount of strong Lewis acidity by introduction of indium into the Sn-Beta catalyst suppressed the side reactions. The coupling of multifunctional active sites provides a new strategy for addressing challenges in commercial lactic acid production.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）