JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Li Peng,Zhengqi Wu,Boxuan Wang,Hua Liu,Chun Zhang,Xuehong Gu
Pure silica MFI (Si-MFI) zeolite membranes with desirable hydrophobicity have the potential to separate ethanol/water mixture. However, its separation performance would significantly decrease in the long-term operation due to the presence of silanol groups formed in alkaline media. In this work, silanol-free MFI zeolite membranes were prepared by the incorporation of tungsten in MFI framework. The occurrence of silanol group can be prevented by formation of W–O–Si bridges. The synthesis parameters affected the W-MFI zeolite membranes’ microstructure and separation performance. For 5 wt% ethanol solution, the W-MFI zeolite membranes prepared at optimum condition showed stable separation performance of permeation flux as 2.81 kg m −2 h −1 with separation factor as 32 over 80 h at 60 °C. The membrane was characterized by XRD , DR UV–vis, XPS and 29 Si NMR, and the results confirmed the incorporation of W and the absence of silanol groups. This research showed that W-MFI zeolite membranes are promising candidates for ethanol extraction with high stability.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Chao Lin,Ting Lü,Dongming Qi,Zhihai Cao,Yangyi Sun,Yiting Wang
In situ free-radical polymerization in the presence of inorganic nanoparticles (NPs) continues to attract intense research interest for the preparation of nanocomposites. In this study, in situ solution polymerization of methyl methacrylate (MMA) in the presence of pristine or surface-modified SiO2 NPs has been successfully carried out. The effects of SiO2 NPs on the initiator decomposition and polymerization rates, as well as the final polymerization conversions, have been systematically investigated. Specifically, the influences of silicon hydroxyl (SiOH), double bonds, and an in situ generated graft layer on the particle surface on initiator decomposition and the in situ polymerization process have been studied in detail. On this basis, a mechanistic rationale for the influence of surface groups on SiO2 NPs on the in situ solution polymerization is proposed. During the in situ polymerization process, the SiOH on the surface of the SiO2 NPs not only accelerates the decomposition of benzoyl peroxide and increases its ineffective consumption, but also enhances the wastage of radicals through chain-transfer reaction. However, when the SiO2 surface bears reactive double bonds, the in situ generated grafted polymer layer is effective in preventing the initiator and free radicals from contacting the SiOH to any considerable extent, thereby enhancing the polymerization rate and the final monomer conversion. The results of this study may also lay down scientific and theoretical foundations for developing more organic–inorganic hybrid nanocomposites through in situ free radical polymerization.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2025
·
IF 17.7
Liwen Guo,Dao Shi,Tianjun Zhang,Yanhang Ma,Guodong Qi,Jun Xu,Qiming Sun
Propane dehydrogenation (PDH) has emerged as a key on-purpose technology for the production of propylene, but it often depends on toxic chromium and expensive platinum catalysts, highlighting the need for environmentally friendly and cost-effective alternatives. In this study, we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co 1 O 3 H x structure by regulating silanol nests in purely siliceous Beta zeolites. Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity. Additionally, the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles. Notably, the optimized Co 0.3% /deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol C3H6 g cat –1 h –1 , with an exceptional propylene selectivity of 99.1% at 550 °C. Moreover, the Co 0.3% /deAl-meso-Beta catalyst demonstrated excellent stability, with negligible deactivation after 5 consecutive regeneration cycles. This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites, providing valuable insights for the design of high-activity, high-stability, and low-cost PDH catalysts.
研究领域:
催化化学
·
材料科学
·
能源化工
✓ 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
Nature Communications
·
2024
·Vol. 15
·期 1
·1-11
·
IF 14.7
Fan Yaqi,Tang Xiaomin,Hu Junyi,Ma Ye,Yang Jiabao,Liu Fengqing,Yi Xianfeng,Liu Zhiqiang,Song Lijuan,Zheng Anmin,Ma Yanhang
The efficient purification of cyclohexane is critical, serving as an essential feedstock to produce resins, nylon fibers and pharmaceutical intermediates. However, efficient purification remains a challenging task due to the similarity of cyclohexane and benzene molecules in terms of size and boiling point. In this work, we reported on the synergy of pore size and silanols inside an -SVR-type zeolite for the efficient production of ultrapure cyclohexane (benzene <1 ppm) from benzene/cyclohexane mixture. Under ambient conditions, the SSZ-74 zeolite demonstrated the highest mass-based productivity of 14.5 L/kg for ultrapure cyclohexane among several common zeolites with a considerable dynamic selectivity of ~9.5. The separation ability was evaluated through density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. The unique ordered silanols inside the zeolite frameworks demonstrated strong but reversible interactions with benzene through SiOH…π interactions, as revealed by in situ Fourier Transform infrared (FTIR) spectra.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NANOTECHNOLOGY
·
2024
·Vol. 35
·期 12
·125601
·
IF 2.9
Xia Pu,Wanling Cai,Huayao Chen,Fujie Yang,Xiaomei Mu
The key step in preparing mesoporous silica is to remove the organic template agent, and the most common method used to achieve this goal is high-temperature calcination. However, this method has many disadvantages, one of which is that it reduces the silanol density on the surface of mesoporous silica, which affects its subsequent modification. Ionic liquids (ILs) are often used as extractants. In this work, the 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) IL is considered, and the effects of its concentration, reaction temperature, and reaction time as well as HCl concentration on the extraction rate and silanol density were investigated using an IL extraction template agent (cetyl trimethyl ammonium bromide (CTAB)). The results show that an IL concentration of 10%, a reaction temperature of 120 °C, a reaction time of 12 h, and an HCl concentration of 1% are the best reaction parameters; with these parameters, the extraction rate and the silanol density were found to be 93.19% and 2.23%, respectively. The silanol density of mesoporous silica treated by calcination is only 0.81%. A higher silanol density provides more reaction sites, so that the modified mesoporous silica treated with the IL can be loaded with more Zn ions.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Yan Chen,Guojun Lv,Xuyang Zou,Shihao Su,Jiangzhang Wang,Chaoyi Zhou,Jialing Shen,Yangbin Shen,Zhongmin Liu
Dealuminated Beta zeolite has a large amount of silanol defects on its interface, which provides an ideal place for embedding metal species and creating metal active sites in a confined microenvironment. The confined metal sites as well as their surroundings are closely related to the reactant activation and transient state achievement. Hence, unraveling the confined metal sites is of great significance for the catalytic reaction process. Herein, niobium species were incorporated into the silanol defects over dealuminated Beta zeolite with a facile dry impregnation method, co-grinding the niobium precursor with dealuminated Beta zeolite support. The successful incorporation of niobium into the silanol defects for 30Nb-Beta zeolite was verified by DRIFT, 1 H MAS NMR, UV–Vis and UV-Raman characterizations. XAS characterization and DFT calculations further disclosed that the confined Nb species existed as (SiO) 2 Nb(OH)(=O), containing two Si−O−Nb bonds, one Nb=O bond as well as one Nb−OH bond. The synthesized 30Nb-Beta zeolite catalyst displayed a superior cyclohexene conversion of 51.1%, cyclohexene oxide selectivity of 83.1% as well as TOF value of 188.2 h −1 ascribed to the inherent electrophilicity of Nb(V) for confined (SiO) 2 Nb(OH)(=O) species as well as the low oxygen transfer energy barrier for Nb V −OOH species. Furthermore, the prepared 30Nb-Beta zeolite can be effectively employed to other cyclic alkene epoxidation reactions.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Tingjun Fu,Lihan Jia,Guoqiang Hou,Zhong Li
Dealuminization over aluminium-containing ZSM-5 could create silanol nests and improve catalytic activity for alkylation of toluene with methanol. However, obviously damaged microporous structure seriously accelerated catalyst deactivation. Here, we demonstrate highly stable alkylation on ZSM-5 by deboronation treatment over boron-containing ZSM-5. 11 B MAS NMR, 1 H MAS NMR and OH-IR suggested that silanol nests with hydrogen bonds were created at the expenses of the removal of skeleton-B atoms. The formed silanol nests promote the adsorption of toluene, inhibit the methanol self-reaction and corresponding the deep alkylation process. Therefore, alkylation efficiency and toluene conversion could reach 70.8% and 33.5%, respectively. Importantly, the microporous structure of deboronized ZSM-5 was well maintained during deboronation, which determined a greatly improved catalytic stability compared with that of traditional dealuminized ZSM-5. Moreover, the deboronized ZSM-5 still presented relatively good catalytic stability under a higher methanol feedstock although the coke deposition was accelerated.
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
CATALYSIS LETTERS
·
2019
·Vol. 150
·期 5
·1445-1453
·
IF 2.372
Ye Yuling,Yao Mengqin,Chen Honglin,Zhang Xiaoming
Abstract The silanol defects in ZSM-5 zeolite have been recognized as an important factor in catalytic activity. Here, ZSM-5 zeolites with different amounts of silanol defect sites were synthesized from synthetic gels containing fluoride medium and were applied as catalysts for trioxane synthesis. The results of XRD, SEM, NH 3 -TPD, Py-IR, OH-IR, 27 Al MAS NMR, 1 H MAS NMR, and TG indicated that all ZSM-5 zeolites showed similar crystal size, relative crystallinity, porosity, and the number of Brønsted acid sites. However, the silanol defects reduced obviously and the number of Lewis acid sites reduced correspondingly when a little NH 4 F was added in the synthesis gels and both of them decreased slightly with increase of F/Si ratio. Compared with ZSM-5 zeolite prepared in hydroxide medium, ZSM-5 zeolite prepared in fluoride medium displayed higher selectivity to trioxane and increased gradually with increase of F/Si ratio. Moreover, the lifetime of ZSM-5 zeolite prepared in fluoride medium was longer than that of prepared in hydroxide medium. Thus, ZSM-5 zeolite prepared in fluoride medium which contained the few silanol defects and low Lewis acid sites is an efficient catalyst for trioxane synthesis. Graphic Abstract
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Yan Cui,Bin Chen,Leilei Xu,Mindong Chen,Cai-e Wu,Jian Qiu,Ge Cheng,Ning Wang,Jingxin Xu,Xun Hu
Hollow ZSM-5 zeolites prepared using different alkaline solutions were employed as Ni based catalyst supports for the methanation of CO 2 . The catalysts were thoroughly characterized, and in-situ DRIFTS were used to study the CO 2 methanation intermediates. Using the hollow Ni-based catalysts led to enhanced CO 2 conversion as well as CH 4 selectivity compared with the traditional Ni/ZSM-5, which was mainly due to the strong basicity of the hollow supports as well as the presence of silicon hydroxyls. Meanwhile, the 15Ni/H-ZSM-5-T catalyst prepared with TPAOH solution had higher catalytic performance than 15Ni/H-ZSM-5-NT and 15Ni/H-ZSM-5-N. The introduction of the hollow zeolite morphology led to enhanced diffusion behavior in the catalyst, which inhibited catalyst deactivation. Therefore, the hollow structure of the support with alkaline treatment was an important consideration for the design and preparation of high-performance Ni-based catalysts for CO 2 methanation.
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 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
·
无机化学
·
多孔材料
·
矿物加工
·
表面改性
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Yong-Xin Wang,Jia-Hao Zhang,Zong-Gong Yin,Hao Su,Qiu-Han Fan,Zhi-Guo Jiang,Ming Yao,Jun Zhang,Gang Xie,Jin Qu
Aqueous zinc batteries (AZBs) are considered ideal candidates for large-scale energy storage systems due to their high capacity, safety, and environmental friendliness, but issues such as dendrite growth, corrosion, and hydrogen evolution on the zinc anode severely restrict their cycling lifespan and reaction reversibility. In this study, a silica nanotube (SNT) material with a three-dimensional hierarchical mesoporous structure was constructed as an interfacial protection layer for the zinc anode to address these limitations. The SNT interfacial layer features a hierarchical mesoporous nanoconfinement structure, continuous ion-conducting pathways, and densely distributed nucleation sites. These structural features, together with the intrinsic hydrophilicity and electrical insulation of SNT, synergistically contribute at the interface to effectively promote the rapid desolvation of Zn2+, enhance its interfacial diffusion rate, and induce progressive and uniform nucleation and deposition on the anode surface, thereby significantly suppressing dendrites accumulation and side reactions. As a result, the SNT@Zn||SNT@Zn symmetric cell stably cycles for over 4500 h at 3 mA cm–2/1 mAh cm–2, with a cumulative capacity of up to 9.6 Ah cm–2. The SNT@Zn||Cu half-cell also exhibits a Coulombic efficiency exceeding 99%. The SNT@Zn||MnO2 full cell can operate continuously for over 4200 cycles at 1 A g–1, while maintaining a high specific capacity and an excellent rate performance, demonstrating promising practical application potential.
✓ 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）