RSC Advances
·
2017
·Vol. 7
·期 54
·33714-33725
·
IF 3.108
Jianhua Li,Haiyan Liu,Tingting An,Yuanyuan Yue,Xiaojun Bao
This article describes a novel method to dealuminate and realuminate H-beta zeolites as catalysts for removing organic acids from bio-oils via their esterification reactions with alcohols. Modified H-beta zeolites were prepared by leaching with solutions of oxalic acid, DL-malic acid, and DL-tartaric acid that have different numbers of hydroxyl groups. The results showed that, while all three organic acids can dealuminate the parent H-beta zeolite, with Al(VI)a atoms and Al(IV)c ones being preferentially removed, they show quite different realumination abilities, with tartaric acid with two hydroxyl groups having the highest realumination ability. The concomitance of dealumination and realumination and their dependence on the hydroxyl group numbers of the organic acids provide the possibility of finely tuning the Al and acidity distributions of the resulting zeolites. Among the three acid treated H-beta zeolites, the one obtained from malic acid leaching exhibited the best performance in catalyzing the esterification reaction between acetic acid and sec-butyl alcohol, attributed to its suitable quantity and density of medium and strong Brönsted acid sites and enhanced aluminum gradient. The catalytic results obtained in a fixed-bed microreactor revealed that the malic acid leached H-beta exhibited dramatically enhanced catalytic performance compared to the commercial ion-exchange resin Amberlyst® 15, demonstrating great potential for industrial application.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Aihu Feng,Yang Yu,Le Mi,Yunzhen Cao,Yun Yu,Lixin Song
In this work, the hierarchical Y zeolites are firstly obtained by etching NaY zeolites with different NH 4 HF 2 solutions. The morphology and microstructure, toluene adsorption property of as-prepared hierarchical Y zeolites are characterized. The results demonstrate that the mesoporous number and size, the n(SiO 2 )/n(Al 2 O 3 ) value of hierarchical Y are increased with NH 4 HF 2 concentration. The 0.3M NH 4 HF 2 -etched NaY exhibits satisfactory crystallinity, suitable mesoporous content and better toluene adsorption performance. The NH 4 HF 2 -etched NaY is an excellent material for pressure swing adsorption. Furthermore, the synthesis mechanism of hierarchical Y has been elaborately demonstrated. The synergistic effect of H + and F − is beneficial to dealumination as well as the introduction of mesoporous. The NH 4 HF 2 ionizes into positive H + and negative F − at a very slow rate, which avoids the concentration of H + and F − going up suddenly. Under the circumstances, the dealumination reaction between NH 4 HF 2 and NaY zeolites is more sustained and mild, and the crystallinity of hierarchical Y zeolites is higher than that of the HCl/NH 4 F-etched or HF/NH 4 F-etched NaY. This work presents an effective method to synthesize the hierarchical Y zeolites.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 101
·期 3
·1591-1601
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IF 2.5
Renjie Deng,Yao Tian,Huajie Liu,Weiwei Yan
This work presents a novel heterogeneous catalytic system for the preparation of para -nitrotoluene ( p -NT) with nitrogen dioxide (NO 2 ) as a nitrating agent in the presence of oxygen (O 2 ). By applying dealuminated Hβ zeolite treated with oxalic acid (Hβ-Ox) as a catalyst, p -NT can be obtained with high conversion (90.5%) and selectivity (72.6%). In addition, it can be recycled at least five times without a significant decrease in catalytic activity. This result demonstrates that the catalyst has high efficiency, good stability, and regenerability. Meanwhile, the characteristics of pristine Hβ and different dealuminated Hβ zeolites modified with organic and inorganic acids were systematic contrastive studied using X-ray diffraction (XRD), nitrogen (N 2 ) adsorption-desorption, Fourier-transform infrared (FT-IR), scanning electron microscope (SEM), temperature-programed desorption of ammonia (NH 3 -TPD), pyridine adsorption infrared (Py-FT-IR), and solid state 27 Al nuclear magnetic resonance ( 27 Al MAS-NMR). Finally, the higher conversion and para -selectivity over Hβ-Ox also give a reasonable explanation in this paper.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
Catalysis Science & Technology
·
2024
·
IF 4.4
Renjie Deng,Huajie Liu,Haishuai Cui,Yao Tian,Hai Yang
In this work, we have developed a green method for the preparation of para-nitrotoluene through the catalytic nitration of toluene with nitrogen dioxide (NO2) under the promotion of dioxygen (O2). The experimental results reveal that the dealumination of Hβ zeolite has a significant effect on the catalysis of the developed NO2–O2–acetic anhydride (Ac2O) system, in which the conversion of toluene is 78.1% and the selectivity to para-nitrotoluene is 71.8%. Furthermore, the nature of different dealuminated catalysts was investigated by nitrogen adsorption–desorption analysis, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), thermal gravimetric analysis (TGA), inductively coupled plasma (ICP), ammonia temperature-programmed desorption (NH3-TPD), pyridine adsorbed Fourier-transform infrared (Py-FT-IR), scanning electron microscopy (SEM) and 27Al magic-angle spinning nuclear magnetic resonance (27Al MAS NMR) techniques. The results of characterization indicate that the structure of the Hβ zeolite still remains and that of Al species in the extra-framework is preferentially removed after acid treatment. Based on the combined results of catalytic characterization and DFT calculation, a feasible reaction mechanism of improved para-selectivity in toluene nitration was suggested for the NO2–O2–Ac2O system.
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
Journal of Materials Chemistry A
·
2024
·
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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产品关联
DOI
高影响因子
ACS Catalysis
·
2020
·
IF 12.35
Peng Liu,Zhi Li,Xingyu Liu,Weiyu Song,Bowen Peng,Xinyue Zhang,Suofu Nie,Penghui Zeng,Zhongdong Zhang,Xionghou Gao,Baojian Shen
In fluid catalytic cracking (FCC), Brønsted acid plays a very important role. Herein, a zinc-modified ultrastable Y (USY) zeolite containing higher Brønsted acidity was prepared by synergistic treatment with zinc chloride and steaming. The results of characterization showed that selective dealumination and silicon healing due to introduction of zinc ions ([ZnCl]+ and [ZnOH]+) into zeolite could promote the formation of extra-framework silicon (EFS) and different silicon healing of the Al vacancies, which led to the formation of half-sodalite cages connecting with supercages and thus increased the availability of acidic sites in the sodalite cage. Meanwhile, DFT calculations demonstrated that the acidic strength of protons in the sodalite cage was enhanced by [ZnCl]+ and [ZnOH]+, and the synergy of Brønsted/[ZnCl]+ became stronger. As a result, the strong Brønsted acid was increased by 19%. This translated to higher n-octane and heavy oil (VGO) catalytic cracking activity and gasoline yield.
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
FUEL
·
2025
·
IF 7.5
Wenqian Song,Yuxin Wen,Guojun Kang,Wenqing Lv,Dekang Li,Haoquan Hu,Lijun Jin,Shijian Lu,Zhong Yan,Pengfei Liu
Amine-based solution absorption as the most promising and commercialized CO 2 capture method, attracted the increasing attention. However, its key lies in improving the CO 2 desorption performance while reducing the energy consumption in desorption. In this paper, HZSM-5 was dealuminated by sulfuric acid, further loaded by Fe 2 O 3 , Co 3 O 4 , NiO and ZnO via impregnation method and used in catalytic desorption of the blended amine solution of N-methyl-diethanolamine and piperazine. Results indicated that sulfuric acid leaching increased the number of acid sites and mesoporous surface area. When sulfuric acid reached 0.8 mol/L, the resultant catalyst (0.8H 2 SO 4 -HZ) improved the amount of the desorbed CO 2 by 10.26% and decreased the heat duty to 2128 kJ/mol CO 2 , with a reduction of 17.01% compared to non-catalytic system. The loading of metal oxides on 0.8H 2 SO 4 -HZ decreased surface area and changed acidity of catalysts. CO 2 desorption amount under catalysis of metal oxide modified M /0.8H 2 SO 4 -HZ followed the order of Fe/0.8H 2 SO 4 -HZ > Zn/0.8H 2 SO 4 -HZ > Ni/0.8H 2 SO 4 -HZ > Co/0.8H 2 SO 4 -HZ, whereas the relative heat duty was in order of Zn/0.8H 2 SO 4 -HZ > Co/0.8H 2 SO 4 -HZ > Ni/0.8H 2 SO 4 -HZ > Fe/0.8H 2 SO 4 -HZ. Fe/0.8H 2 SO 4 -HZ exhibited excellent catalytic performance, along with 12.82% increase in amount of CO 2 desorbed and reduction in heat duty to 2039 kJ/mol CO 2 , with a 20.49% decrease. Meanwhile, Fe/0.8H 2 SO 4 -HZ showed good stability after ten cycles and the addition of Fe/0.8H 2 SO 4 -HZ promoted CO 2 absorption. Suitable pore structure and abundant acid sites of the modified catalyst contributed to proton transfer and decomposition of carbamate. A possible mechanism for catalytic desorption over modified HZSM-5 was proposed. The work indicates that catalytic desorption by modified HZSM-5 catalyst is a promising way to decrease the energy consumption of amine solution regeneration.
研究领域:
化学工程
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环境科学
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能源化学
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催化化学
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气体分离
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材料科学
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工业催化
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Cheng Wang,Shaozheng Leng,Huidong Guo,Jiale Yu,Wenjie Li,Liyun Cao,Jianfeng Huang
Acid treatment is an effective way to arrange SiO 2 /Al 2 O 3 ratio of natural zeolite . However, limited researches have been done on quantitative regulation of SiO 2 /Al 2 O 3 ratio of natural zeolite . In this paper, an orthogonal test was designed to optimize the acid treated conditions. Acid concentration, treated time and temperature were then employed to quantitatively arrange the SiO 2 /Al 2 O 3 ratio of natural zeolite, respectively. The results showed that the primary and secondary factors of acid treatment were acid treated time, acid concentration and acid treated temperature, respectively. The extent of dealumination of zeolite and its corresponding SiO 2 /Al 2 O 3 ratio of natural zeolite could rise up to 98.4% and 372.7 under the optimized condition for 48 h, 8 M and 70 °C, respectively. Acid concentration, treated time and temperature could effective quantitatively arrange the extent of dealumination of zeolite and SiO 2 /Al 2 O 3 ratio of natural zeolite. The as-prepared acid treated zeolites with different SiO 2 /Al 2 O 3 ratio regulated by acid concentration had higher specific surface area , micropore volume, silanol group content and hydrophobicity than those for the natural zeolite.
研究领域:
材料科学
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无机化学
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多孔材料
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矿物加工
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表面改性
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Xun Zhou,Shaojie Wu,Yongming Luo,Linhua Zhu,Dedong He
Propane dehydrogenation (PDH) is a very important and efficient propylene production process. Currently, it is a challenge to design a catalyst that can replace precious Pt and toxic Cr. Ni species are widely used in reactions for the activation of C–C and C–H bonds, but making Ni species active sites for alkane dehydrogenation is a challenge. In this paper, a series of catalysts with different Ni loadings were impregnated onto dealuminated β zeolite, and it was observed that low loadings of the metal could improve Ni dispersion and produce a high amount of Lewis acid sites, thus inhibiting the side reactions during the PDH process. The characterization results demonstrated that Ni species at low loadings were successfully introduced into vacancy defects over the dealuminated β zeolite. Moreover, good dispersion of Ni sites and excellent reactivity were obtained, with 42% initial propane conversion and a high propylene generation rate of 0.8 g–1·h–1, which was higher than those of many other metal catalysts. This study provides new ideas for the development of economical and environmentally friendly PDH catalysts.
研究领域:
催化化学
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材料化学
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工业催化
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能源化学
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多相催化
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表面科学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Xu Yue,Sheng Wang,Shudong Wang
ZSM-5 zeolite adsorbents exhibit limited adsorption capacity for volatile organic compounds (VOCs) under high-humidity conditions, constraining their industrial applicability. In this study, a series of hierarchical ZSM-5 zeolites with high silica-to-alumina ratios (SARs) were successfully prepared via a facile acid pretreatment followed by surface methyl grafting. Using toluene as a representative VOC, the adsorption and desorption properties of these samples were assessed through dynamic adsorption breakthrough curves and temperature-programmed desorption (TPD) experiments. It was found that the two-step modification significantly enhanced both the breakthrough time and saturation adsorption capacity of high-SAR ZSM-5 for toluene in the presence of water vapor. AHFS-TZ5 and HCl-TZ5 exhibited superior performance, showing 53.9 % and 59.5 % enhancements in breakthrough time over ZSM-5, respectively. Specifically, the toluene adsorption capacity of AHFS-TZ5 under humid conditions (4 vol% H 2 O) reached 67.38 mg·g −1 , approximately 1.47 times higher than that of the unmodified ZSM-5. However, the hydrophobic -CH 3 groups grafted onto the ZSM-5 surface moderately hindered toluene diffusion due to increased steric hindrance. Additionally, AHFS-TZ5 exhibited excellent regeneration ability after desorption at 180 ºC, retaining 95 % of its initial adsorption capacity. This study provided a promising approach for preparing hydrophobic zeolites, offering a potential solution for efficient VOC adsorption in high-humidity flue gas environments.
研究领域:
环境科学
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材料化学
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吸附分离
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大气污染控制
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多孔材料
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Qiang Yu,Wenna Zhang,Junjie Li,Wen Liu,Yanan Wang,Weifeng Chu,Xinbao Zhang,Longya Xu,Xiangxue Zhu,Xiujie Li
Although FAU zeolites have been widely used as absorbents for volatile organic compounds (VOCs) removal, preparation of high-silica FAU zeolite to expand its application under high humidity is still a big challenge. Here, two high-silica FAU zeolites were successfully prepared through the controllable framework modulation strategy. By carefully matching the degrees of dealumination and Si-insertion, the zeolite (FAU-H) with an ultra-high SiO 2 /Al 2 O 3 ratio of 957 was obtained. FAU-H exhibited similar high adsorption capacities of VOCs (e.g. m-xylene and toluene) under dry and humid conditions, more importantly, its adsorption capacity of m-xylene was 25% higher than the industrial high-silica FAU zeolite (HSZ-390HUA) from Tosoh Corporation. When the dealumination degree was mismatched with that of Si-insertion, imperfect FAU-M (SiO 2 /Al 2 O 3 = 108) with the existence of some defect sites was obtained that becomes a good candidate for the adsorption removal of small VOCs molecules (e.g. isopropanol). The moderate interaction between VOCs and zeolite framework is proved a key factor for small molecules adsorption on basis of the DFT calculations. Moreover, the fitted kinetic models, desorption tests, and adsorption−desorption cycling tests proved the good regenerability of FAU-H and FAU-M. Therefore, the proposed high-silica FAU zeolites are promising adsorbents for VOCs removal.
研究领域:
材料科学
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环境工程
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化学工程
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产品关联
DOI
高影响因子
Toxics
·
2025
·Vol. 13
·期 9
·737
·
IF 4.1
Wenqi He,Zhipeng Qie,Huaizhong Xiang,Hassan Alhassawi
Zeolites are promising materials for volatile organic compound (VOC) adsorption and catalytic oxidation, where tuning their structure via defect engineering can enhance adsorption capacity and active metal dispersion. In this study, a concentration-sensitive chelation strategy using diethylenetriaminepentaacetic acid (DTPA) was developed to achieve moderate dealumination for Beta and Y zeolites. For Y zeolite, 0.1 M DTPA treatment increased the toluene adsorption capacity from 59 to 110 mg/g. After platinum (Pt) loading, both DTPA-modified Beta- and Y-based catalysts showed improved toluene oxidation efficiency compared to their unmodified counterparts. Remarkably, the Y-DTPA-0.01-Pt catalyst achieved 90% toluene conversion at 150 °C with CO2selectivity above 90%. DRIFTS and H2-TPR results confirmed that moderate dealumination by DTPA generated silanol defects in zeolite Y that strongly anchored Pt2+in a highly dispersed form and suppressed PtO formation. Severe dealumination using 0.1 M DTPA created larger defects that favored the aggregation of Pt0clusters whilst causing significant loss in the micropores, thus reducing the Pt loading content and catalytic activity. This work demonstrates a simple and effective approach to optimize zeolite-based catalysts by controlling defect formation through controllable chelation, offering new insights into VOC abatement via tailored support design.
研究领域:
环境科学
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催化
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）