FUEL
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2022
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IF 8.035
Yueqing Wang,Hongxing Wang,Junbo Zhang,Hongyan Zheng,Long Huang,Yulei Zhu
Selectively converting fructose into furfural by H-beta catalyst is a very interesting catalytic process. However, it is a challenging task to clearly elucidate the roles of framework Al for selective scission of C C and C O bond. Herein, selective elimination of framework Al atoms is realized. Several detailed investigations showed that the framework Al species located in different sites play important role in furfural formation. The framework Al atoms of pristine H-beta mainly occupied at T1, T2, T5, T6 and T7 sites. These Al species at pore mouth can be removed by citric acid, while the treatment of nitric acid mainly eliminated the framework Al atoms from T2 and T7 sites. As for oxalic acid, the Al atoms occupied at T2, T5, T6 and T7 was primarily leached. Upon citric acid and nitric acid treatment afforded the similar yield of furfural, indicating that the formation of furfural could not be governed by these Al species at pore mouth, T2 and T7 sites. However, in the case of oxalic acid treatment, complete removal of the Al species on T2, T5, T6 and T7 sites decreased the yield of furfural. Thus, it is reasonably inferred that these Al atoms populated at T1 sites and intersecting channels is more encouraging for the splitting of C C bond, while the Al species occupied at T5, T6 sites and the larger straight channels is probably more favorable to scission of C O bond.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
Journal of Materials Chemistry A
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2024
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IF 10.7
Yuhui Huang,Yehan Tao,Qingqing Wang,Jian Du,Jinwen Hu,Jie Lu,Yanna Lv,Haisong Wang
To develop an industrial zeolite-based catalyst for efficient furfural production, the acidity, pore structure, and electronic properties of H-β zeolite were modulated by synergistic deatomization and atomic implantation treatments. The dealumination effectively decreased the intrinsic aluminum-related Lewis and Brosted acid sites, thus decreasing the occurrence of unwanted side reactions. Meanwhile, the removed skeleton aluminum can create voids for the following atomic implantation of introducing higher valent-state niobium species, which would provide new kinds of catalytic active sites, increase the average pore size by distorting the zeolite skeleton, and enhance the interaction with reactant molecules by acting as more electron deficient centers. In a single-phase water/γ-valerolactone reaction system, the optimum catalyst can efficiently convert both xylan and xylose with a conversion of 100 % at a medium temperature of 130 ℃ within 3 hours. Compared with the furfural yield over untreated H-β (12.7%), the yield over deAlβ/Nb(20%) catalyst was greatly enhanced by 54% with xylose as raw material. The catalyst can be recovered by simple cleaning and thermal regeneration and then reused. The proposed post-treatment strategy could maintain the integrity of the zeolite structure, ensure uniform and stable metal dispersion under harsh conditions, manage the complexity and cost of the preparation process, and most importantly, optimize the catalytic performance. Addressing these issues is essential for improving the efficiency and practical application of industrial zeolite catalysts by this general approach and benefiting industrial furfural production.
研究领域:
化学工程
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催化材料
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DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
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2023
·Vol. 98
·期 7
·1620-1630
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IF 3.4
Minhua Zhang,Yan Zhang,Yuxin Tan,Guochao Yang,Haoxi Jiang,Lingtao Wang
BACKGROUND With the improvements in bioethanol production, the process of converting ethanol to 1,3-butadiene (ETB) has received substantial scholarly attention, whose industrialization has been constrained by the stability of the catalysts. RESULTS In this work, the deactivation behavior of Zr- β zeolite in the process of ethanol/acetaldehyde conversion to 1,3-butadiene was investigated. In addition, the deactivation kinetics of ETB was studied using an isothermal differential microreactor. A kinetic model was developed and parametrized with the Langmuir–Hinshelwood mechanism, and the intrinsic kinetic equation was derived. The deactivation kinetic model of the ETB reaction was established from the active site content of the catalyst as a function of time on stream. The validity of the kinetic model was tested, and the results were found to be accurate. CONCLUSIONS Catalyst deactivation was mainly caused by coke species, which are mainly long-chain unsaturated oxygenated organic compounds and aromatic compounds, covering Lewis acid sites in the microporous channels of the catalyst; nevertheless the zeotype topology and morphology were not destroyed. The kinetic data suggested that the reaction was of first order and the activation energy of the deactivation process was 75.59 kJ mol −1 . © 2023 Society of Chemical Industry (SCI).
研究领域:
化学工程
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催化科学
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DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2018
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IF 6.14
Xiaomei Yang,Ying Liu,Xiaoxin Li,Jinxiu Ren,Lipeng Zhou,Tianliang Lu,Yunlai Su
Rapid synthesis of Sn-containing nanosized all-silica Beta zeolite was developed in this work. The method employed all-silica Beta (Si-Beta) as parent, which was crystallized in several hours by the hydrothermal method, and incorporated Sn to Si-Beta through grinding with SnCl4·5H2O and subsequent calcination procedure. The prepared Sn-Beta zeolites were analyzed by several methods including XRD, SEM, N2 physisorption, FT-IR spectroscopy of deuterated acetonitrile and pyridine adsorption, UV–vis DR, and XPS. The mechanism of incorporation of Sn sites into the framework of zeolite was revealed. The results show that the successful incorporation of Sn sites strongly depends on the crystallinity of the parent Si-Beta. Si-Beta with lower crystallinity (<90%) had a considerable amount of silanols which provided sites for Sn incorporation into the framework sites. For Si-Beta with higher crystallinity and less silanols, desilication was used to generate more silanols for the incorporation of Sn sites. The prepared Sn-Beta zeolites were effective for the transformation of glucose to methyl lactate (MLA). Its catalytic activity is better than those of Sn-Beta-P prepared by dealumination–stannation of Al-Beta and Sn-Beta-F synthesized through the traditional hydrothermal method. Turnover frequency (TOF) was calculated on the amount of framework Sn sites to measure the intrinsic and initial activity of active Sn sites. TOF values varied in the sequence of nano Sn-Beta ≫ Sn-Beta-F ≫ Sn-Beta-P. The high MLA yield for nano Sn-Beta is due to its higher mesoporosity. The prepared Sn-Beta zeolite was recycled eight times in the transformation of glucose to MLA without any decrease of catalytic activity. Additionally, the effect of potassium salt on the formation of MLA from glucose over Sn-Beta catalyst was studied.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
CATALYSIS COMMUNICATIONS
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2023
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IF 3.7
Haoxi Jiang,Xinyi Ni,Angjiong Jiang,Guochao Yang,Lingtao Wang
Zr-β zeolites were modified with second metals to catalyze the conversion of ethanol/acetaldehyde to 1,3-butadiene. The incorporation of Ta increases the Lewis acidity of Zr-β zeolite, resulting in higher catalytic activity than that of In, Y and Ce. Furthermore, the Zr-β zeolite that was first incorporated with Zr and then Ta with a Ta/Zr molar ratio of 1.5 exhibited greater catalytic activity of 57% conversion and 75% selectivity. Activity descriptors were proposed to calculate the reactivity of key reaction steps, which served as evidence that Ta incorporation enhances the aldol condensation and MPV reduction reaction activity, thus improving catalytic performance.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
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IF 8.025
Xinyi Xing,Xian Shi,Rui Hu,Ying Guan,Hui Gao,Siquan Xu
In this work, a series of (x)Hf-β zeolite catalysts were prepared by a simple wet impregnation method and used as bifunctional catalysts with Lewis and Brønsted acid sites for synthesizing 5-hydroxymethylfurfural (5-HMF) from cellulose in H 2 O (NaCl) -THF biphasic system. Characterization analysis of (x)Hf-β zeolite catalysts with ICP-OES, N 2 adsorption-desorption isotherm, XRD, FTIR , SEM, NH 3 -TPD and Py-FTIR indicated that the catalysts possessed favorable pore structure, appropriate acid strength and acidity. A superior 86.3 % cellulose conversion and 53.4 % 5-HMF yield could be obtained at 200 °C for 4 h by using (5 %)Hf-β zeolite as the catalyst. In addition, the catalytic system provided a favorable 5-HMF yield from other carbohydrates, including glucose (85.1 %), sucrose (80.6 %), starch (65.1 %), maltose (65.0 %), dextran (59.9 %), and Moso bamboo (21.9 %). Nevertheless, the recyclability of (5 %)Hf-β zeolite catalyst was unsatisfactory and the 5-HMF yield showed a downtrend from 53.4 % to 24.4 % after 5 cycles. The catalyst has promising potential for converting biomass materials into high-value platform compounds.
研究领域:
化学工程
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催化科学
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生物质转化
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DOI
PubMed
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2015
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IF 1.964
Wenchao Ren,Zile Hua,Tongguang Ge,Xiaoxia Zhou,Lisong Chen,Yan Zhu,Jianlin Shi
Hierarchically structured Ti-β zeolites were prepared using a two-step post-synthesis approach. The physicochemical properties of the resultant Ti- m β-S x materials were determined using various techniques, including X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, and ultraviolet-visible and ultraviolet-Raman spectroscopies. The porous structures of the synthesized hierarchical Ti-β zeolites were well preserved. Their catalytic performance was compared with that of pure microporous Ti-β materials using alkene epoxidation as a model reaction. It was found that although comparable catalytic activities were obtained for both types of catalyst in the epoxidation of small molecules, e.g., cyclohexene, the synthesized hierarchical Ti-β gave an enhanced catalytic performance in the epoxidation of bulky 1-dodecene.
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
RSC Advances
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2015
·Vol. 5
·期 125
·103695-103702
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IF 3.84
Yuannan Xiong,Wenqi Chen,Jianjun Ma,Zhihua Chen,Aiwu Zeng
The continuous liquid-phase Friedel–Crafts acylation of furan with acetic anhydride was first carried out in a fixed-bed reactor over an H-beta zeolite. A three-level, four-variable Box-Behnken design combined with response surface methodology was employed to determine the optimal acylation conditions, and the accuracy of the model was verified by validation experiments. In this study, it was found that lower liquid velocity and stronger polarity of the solvent were conducive to enhancing the catalytic activity and stability of the H-beta zeolite. The reaction was limited by the acid sites being poisoned due to the adsorption of the by-product and pore blockage. Moreover, the carbon deposit was proved to be the main reason for the deactivation of the H-beta zeolite by using GC-MS, 13C NMR MAS, 27Al NMR MAS, TG/DTG and NH3-TPD.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
CATALYSIS TODAY
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2022
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IF 6.562
Xinyi Xing,Ying Guan,Liping Zhang,Xian Shi,Han Wu,Hui Gao,Siquan Xu
A catalytic system that is both efficient and recyclable is desirable for production 5-hydroxymethylfurfural (HMF) from glucose. In this study, the catalytic system composed of H 2 O (NaCl) -tetrahydrofuran (THF) biphasic system and H-β zeolite was found to have excellent performance for the glucose conversion into HMF. The physicochemical properties of the H-β zeolite catalyst, the dosage of the system components, and the reaction parameters were investigated in detail to optimize the production efficiency of HMF. Under optimal reaction conditions, an advanced level of 84% HMF yield was obtained from glucose. After the reaction was completed, all components of the catalytic system can be recovered, realizing no waste of reagents. Moreover, the recycled H-β(30) zeolite catalyst maintained considerable catalytic stability after five consecutive cycles. Therefore, it is reasonable to believe that the efficient, inexpensive, and recyclable H 2 O (NaCl) -THF catalytic system containing H-β(30) zeolite is capable of showing promising application potential in the future.
研究领域:
催化化学
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可再生资源转化
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产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
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IF 4.326
Yunlong Xu,Linlin Yang,Chunying Si,Shuoqi Zhang,Quanxing Zhang,Guixiang Zeng,Wei Jiang
Sn-beta zeolite is a promising catalyst for the direct synthesis of lactide from lactic acid; here, we clarify the relationship between its local structure and activity through the interplay of experiments and DFT calculations. The open sites (HO-Sn-(OSi)3 with adjacent Si–OH) play a key role in the high activity of Sn-beta zeolite, where the reaction rate significantly decreases from 0.2258 mmol min–1 gcat–1 to 0.0724 mmol min–1 gcat–1 if the open sites were masked with Na+. Density functional theory (DFT) calculations show that the decrease in reaction rate comes from the weaker interaction between substrate and the open Sn site by Na+ exchange, which leads to the significant increase in the Gibbs energy barrier from 34.0 kcal/mol to 57.2 kcal/mol (rate-determining step). Other activities of heteroatom M-beta zeolites (where M = Ti, Zr, Hf) were also investigated, where the open sites were found to be crucial for the high activity in the direct synthesis of lactide as well. The information provided by this work is valuable for precise design of efficient catalysts for the one-step synthesis of lactide.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
Molecular Catalysis
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2023
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IF 4.6
Xiaomei Yang,Jie Hu,Tianliang Lu,Lipeng Zhou
Sucrose is an abundant, cheap and sustainable substrate for producing high value-added chemicals. In this work, the role of weak Brønsted (B) acid site of Sn-β zeolite was revealed in sucrose conversion to methyl lactate (MLA). Sn-β zeolites were prepared by post-synthesis and hydrothermal synthesis in F ‒ media and modified by Mg 2+ to tune the B acidity. The acidity of the zeolites was characterized by FT-IR spectroscopy of pyridine/CD 3 CN adsorption and hydroxyl region. Their catalytic performance for sucrose conversion to MLA in methanol indicates that weak B acid sites of silanols are indispensible for breaking the glycosidic bond of sucrose, so the highest MLA yield was obtained over the postsynthesized Mg-Sn-β-P with moderate amount of weak B acid sites of silanols, strong L acid sites and no strong B acid sites, which juggled the alcoholysis/hydrolysis of sucrose and the retro-aldol of C 6 monosaccharide to MLA, and at the same time inhibited the dehydration side-reaction.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2024
·Vol. 14
·期 12
·924
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IF 3.8
Yu Yue,Guozhi Zhu,Min Liu,Yue Zhu,Weilong Ji,Xiaoqin Si,Tianliang Lu
As an important biomass resource, γ-valerolactone (GVL) shows considerable potential for applications in biofuel production, organic synthesis, polymer, and food industries. Herein, an effective method was presented for synthesizing GVL through the catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) under mild conditions. Using isopropanol as a hydrogen donor, a 100% conversion of ethyl levulinate and an 88.7% yield of GVL were achieved over 2%Zr-Beta-7d catalyst at 110 °C for 8 h. The acidic sites of synthesized Zr-Beta via hydrothermal methods easily adjusted and offered high catalytic activity and selectivity. The Lewis (L) acid sites on the zeolite serve as the active centers for the conversion of EL. Characterization results indicate that the amounts of L acid sites on Zr-Beta increased with the Zr content and crystallization time rose, thus enhancing the selectivity for GVL. Additionally, the influences of catalyst dosage, reaction temperature, and time on catalytic performance are studied, as well as calculations of kinetic parameters such as reaction rate constants and activation energies. The 2%Zr-Beta-7d catalyst retains its high performance after five cycles. The current research may present an efficient approach for the conversion of EL to GVL under mild conditions.
研究领域:
生物质化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）