APPLIED CATALYSIS A-GENERAL
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2013
·
IF 3.41
Cheng Liu,Jiale Huang,Daohua Sun,Yao Zhou,Xiaolian Jing,Mingming Du,Haitao Wang,Qingbiao Li
Anatase type extra-framework titanium in titanium silicate-1 (TS-1) molecular sieves has been observed to cause adverse catalytic impediments such as carbon–carbon bond cleavage and low H 2 O 2 efficiency during the epoxidation of terminal alkenes. In this study, a series of TS-1 sieves were synthesized, and used as catalysts for styrene epoxidation. Among the catalysts, the TS-1 with a Si/Ti molar ratio of 35 and 0.21 mol% of anatase type extra-framework titanium exhibited the best styrene conversion and styrene oxide (SO) selectivity. The results suggests that, framework Ti species have no effect on the stabilization of SO selectivity, whereas the synergetic interaction between the framework Ti species and the anatase type extra-framework titanium is essential for the outstanding catalytic performance of TS-1 in styrene epoxidation. In addition, our results demonstrate that the usage of tetraethyl orthosilicate (TEOS), tetrabutyl titanate (TBOT), and isopropyl alcohol in the synthesis of TS-1 does not guarantee the absence of extra-framework Ti species. Instead, the asynchronous degrees of hydrolysis between TEOS and TBOT might account for the formation of the anatase type extra-framework titanium. The influence of H 2 O 2 amount, reaction temperature and time, as well as the types of solvent, oxidant, and catalyst amount, on the catalytic performance of TS-1 with anatase type extra-framework titanium was likewise investigated.
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
·
2014
·
IF 4.058
C. Shen,Y.J. Wang,J.H. Xu,G.S. Luo
Porous glass supported with titanium silicalite (TS-1) particles were successfully prepared and used for oxidative desulfurization (ODS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Uniform-sized TS-1 particles were homogeneously dispersed on the surface of the porous glass beads. Effects of reaction duration, catalyst content, initial concentration, oxidant amount, and temperature on conversions were investigated. The prepared catalysts showed excellent catalytic performance. The optimal mole ratio of oxidant-to-DBT was 10 or 15. Complete conversion was obtained within 3 min at 343 K using catalyst with Ti content of 0.507 wt.%. Compared with other studies, the space–time yield was increased by one order of magnitude without any addition of solvent or metal nanoparticles. Experimental results and computer simulations revealed that the coordinated state of Ti species has a key role in the catalytic activity. Spent catalyst would be regenerated by heating at high temperature, no decrease was observed in catalytic activity after three cycles.
研究领域:
化学工程
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催化材料
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2023
·
IF 7.3
Yu Cao,Gan Tao,Wei Li,Chuanding Dong,Jingdai Wang,Yongrong Yang
Manipulating the interplay between electron donor and catalytic species is a major approach of optimizing Ziegler-Natta catalysts. To this end, it is essential to reveal the correlation between the involved dynamic processes. In this work, a greatly enhanced mobility of the internal donor tetrahydrofuran (THF) is realized even at room temperature in the MgCl 2 substrate modified with MgCl functionalized polyhedral oligomeric silsesquioxane (POSS-MgCl). A series of spectroscopic characterizations evidence that, thanks to the high mobility of THF, the immobilization of catalytic Ti species and the migration of THF occurs synchronously and leads to a nearly homogenous distribution of Ti sites. In addition, the incorporation of POSS-MgCl promotes the formation of 4-coordinated Mg sites in the substrate. The modified Ziegler-Natta catalyst shows the remarkable performance toward ethylene polymerization, featured by the high catalytic activity (21.6 × 10 6 g PE(mol Ti·h) −1 ) as well as a narrow polydiversity index (3.1) of the synthesized polyethylene. Based on these results, we propose that the Ti immobilization process is directly modulated by the THF migration in this system, which reduces the aggregation of TiCl 4 and enhances the formation of active species.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Beining Luo,Yan Wang,Yingqi Zhang,Caifeng Qiu,Guoqiang Yu,Liang Li,Xianzai Yan,Guoqiang Wu
Catalytic epoxidation limitations of conventional ellipsoid titanosilicate-1 (TS-1) remains owing to the narrow microporous channels and low efficiency of the Ti species. Herein, two-dimensional planer TS-1 zeolite (TS-1-P) was synthesized by adding crystal growth regulator in the hydrothermal synthesis process, and then TS-1-P supported molybdenum (Mo/TS-1-P) and mesoporous Mo/TS-1-P (Mo/MTS-1-P) were prepared and applied in epoxidation of olefins. The TS-1-P and the modified TS-1-P catalysts show a similar MFI framework and grain morphology but the different pore structure and coordination environment of Ti or Mo species. Especially, the Mo/MTS-1-P possesses many mesoporous pore and highly dispersed Mo species, which can improve the coordination environment of Ti species and weaken the Ti-O bond, the results are beneficial for the framework Ti species to combine more easily with H 2 O 2 to C=C band of the olefin molecules. Therefore, compared with TS-1-P, Mo/MTS-1-P exhibits the highest conversion of ACH (91.78 %) and 1-hexene (47.44 %) in the epoxidation of ACH and 1-hexene, respectively, the selectivity of epoxidized products simultaneous is above 96.42 % and 94.04 %, respectively. Moreover, the deactivation behavior of carbon deposit on the catalyst surface and regeneration method were also proposed. The successful preparation of Mo/MTS-1-P not only results in an efficient catalyst for epoxidation process but also provides a possible approach for surface and pore structure modification of TS-1 zeolite.
研究领域:
催化化学
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材料科学
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绿色化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ORGANOMETALLIC CHEMISTRY
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2014
·
IF 2.302
An-Lin Zhang,Li-Wen Yang,Nian-Fa Yang,Jing Zhang
Several C 3 -symmetric trialkanolamines can be efficiently obtained via molecular sieve-assisted epoxide ring opening with ammonia in high yields (up to 90%) and regioselectivity up to 100%. These trialkanolamines were effective for the asymmetric alkynylation of aldehydes and the propargyl alcohols were obtained in high yields (up to 92%) and high enantiomeric excesses (up to 95%). The 1 H NMR spectra support that there could be a complex mixture of polynuclear Ti(IV)-based species form from the interaction of Ti(IV) with ligand.
研究领域:
有机化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2023
·
IF 3.8
Zhenyuan Yang,Yanan Guan,Lei Xu,Yangtao Zhou,Xiaolei Fan,Yilai Jiao
This work presents the development and systematic study of a method to prepare hierarchical titanium silicalite-1 (TS-1) zeolites with high tetra-coordinated framework Ti species content. The new method involves (i) the synthesis of the aged dry gel by treating the zeolite precursor at 90 °C for 24 h; and (ii) the synthesis of hierarchical TS-1 by treating the aged dry gel using tetrapropylammonium hydroxide (TPAOH) solution under hydrothermal conditions. Systematic studies were conducted to understand the effect of the synthesis conditions (including the TPAOH concentration, liquid-to-solid ratio, and treatment time) on the physiochemical properties of the resulting TS-1 zeolites, and the results showed that the condition of a TPAOH concentration of 0.1 M, liquid-to-solid ratio of 1.0, and treatment time of 9 h was ideal to enable the synthesis of hierarchical TS-1 with a Si/Ti ratio of 44. Importantly, the aged dry gel was beneficial to the quick crystallization of zeolite and assembly of nanosized TS-1 crystals with a hierarchical structure (Sext = 315 m2 g–1 and Vmeso = 0.70 cm3 g–1, respectively) and high framework Ti Species content, making the accessible active sites ready for promoting oxidation catalysis.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
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IF 3.375
Yunpeng Hu,Kai Wang,Chunli Han,Tao Wang,Guangsheng Luo
A novel liquid–liquid microdispersion method for the synthesis of TS-1 has been developed by continuous preparation of the precursor. In the novel process, the solution of TBOT in n-hexane could be very uniformly dispersed into the oligomeric silicate prehydrolysis mixture to form microdroplets by a microsieve pore reactor. Due to the fast mixing and very high mass transfer performance of the microdispersion process, the Ti species could be uniformly distributed into the mixture and were more likely to condense into the oligomeric silicate precursor species rather than appear with self-condensation. The prepared samples had a minimum molar ratio of Si/Ti at 51 without extra-framework Ti species. Furthermore, the solvent of n-hexane can be recycled by simple phase separation rather than evaporation under the conditions of using isopropanol, which reduced energy consumption. This continuous microdispersion technology could be controllable and a reliable scaling-up for the preparation of TS-1.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2022
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IF 5.876
Saisai Ran,Hanfang Liu,Xiaolong Li,Huijie Xie,Wei Xu,Bin Li,Yu Yang,Yongming Chai,Lei Wang
Utilizing silica-rich wastes for synthesis of zeolite can realize a green production protocol and make best use of solid waste. However, industrial solid wastes usually require a complicated pretreatment process and their surface properties are underestimated for the final products. In this study, silica wastes with different acid or basic surface properties are directly used for the solvent-free synthesis of TS-1 zeolites. The states of Ti species, Si/Ti molar ratios, and morphology of final TS-1 zeolites can be controlled by the pristine surface properties and additional ammonium carbonate. TS-1 zeolite synthesized from acid silica waste exhibits lower crystallinity, abundant highly coordinating titanium species, and an elongated c-axis compared to that from basic silica waste. More importantly, TS-1 zeolite ( n S i / n T i = 30 ) synthesized from silica with acid property possesses excellent performance in the epoxidation of chloropropene with 66.2% conversion and 98.5% selectivity to epichlorohydrin, which is attributed to the presence of abundant high-coordination Ti species of mononuclear TiO 6 . Our strategy provides a novel idea for totally green synthesis of zeolite by utilizing solid wastes.
研究领域:
材料科学
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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
CRYSTAL GROWTH & DESIGN
·
2025
·
IF 3.4
Hongyu Wang,Fumin Wang,Kaiwei Wang,Xubin Zhang,Changhao Bing,Xiaolu Fan,Tongxue Zhang,Syed Mujtaba ul Hassan
Developing an approach for the efficient synthesis of TS-1 zeolites with desirable morphologies and tunable coordination environments for Ti active sites is a pivotal challenge in the design of high-performance catalysts and zeolite crystal engineering. Herein, we report a cost-effective and efficient additive, guanidinoacetic acid (GAA), and conduct a systematic study on the synthesis of plate-like TS-1 zeolites using GAA as an additive. Introducing GAA during hydrothermal synthesis not only modulates the morphology of TS-1 crystals but also permits GAA to adequately chemically interact with titanium precursors to form hexa-coordinated Ti species. TS-1 zeolites with a controllable b-axis thickness in the range of 80–110 nm, and abundant framework Ti and hexa-coordinated Ti species are successfully achieved by optimizing the synthetic parameters. Through SEM, FT-IR, XPS, TEM, and XRD analysis, the mechanism of GAA altering crystal growth is mainly to inhibit the growth of the (010) plane. A b-axis-oriented TS-1 zeolite enriched with hexa-coordinated Ti species displays better catalytic performance in the 1-hexene epoxidation reaction than the conventional TS-1 zeolite containing only framework Ti species (35 vs 24%). This can be ascribed to the more active hexa-coordinated Ti species and shorter diffusion distance. This synthetic strategy provides a way to change the zeolite morphology and tune the number and distribution of Ti species in TS-1 zeolites.
研究领域:
催化材料
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晶体工程
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化学合成
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产品关联
DOI
高影响因子
Aggregate
·
2023
·Vol. 4
·期 4
·e318
·
IF 18.8
Chang'an Wang,Guoqing An,Jing Lin,Xiaowei Zhang,Zhiyuan Liu,Yibin Luo,Siqi Liu,Zhixiang Cheng,Tingting Guo,Hongyi Gao,Ge Wang,Xingtian Shu
Simultaneous achievement of constructing mesopores and eliminating anatase is a long-term pursuit for enhancing the catalytic performance of TS-1. Here, we developed an aromatic compounds-mediated synthesis method to prepare anatase-free and hierarchical TS-1 for olefin epoxidation. A series of hierarchical TS-1 zeolites were prepared by introducing aromatic compounds containing different functional groups via the crystallization process. The formation of intercrystalline mesopores and insertion of titanium into framework were facilitated at different extent. The synergistic coordination of carboxyl and hydroxyl in aromatic compounds with Ti(OH) 4 realizes the uniform distribution of titanium species and eliminates the generation of anatase. Noteworthily, eight machine learning models were trained to reveal the mechanism of additive functional groups and preparation conditions on anatase formation and microstructure optimization. The prediction accuracy of most models can reach more than 80%. Benefiting from the larger mesopore volumes (0.37 cm 3 ·g −1 ) and higher content of framework Ti species, TS-DHBDC-48h samples exhibit a higher catalytic performance than other zeolites, giving 1-hexene conversion of 49.3% and 1,2-epoxyhenane selectivity of 99.9%. The paper provides a facile aromatic compounds-mediated synthesis strategy and promotes the application of machine learning toward the design and optimization of new zeolites.
研究领域:
催化
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化学工程
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材料科学
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机器学习
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产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 10
·6205-6213
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IF 12.732
Jiacheng Xing,Danhua Yuan,Hanbang Liu,Yansi Tong,Yunpeng Xu,Zhongmin Liu
The synthesis of TS-1 zeolites is regarded as a milestone in zeolite history, and it has led to the revolution of the green oxidation system of using H2O2 as an oxidant, leaving only water as the byproduct. However, because of the highly hydrolyzable titanium source, the preparation of TS-1 requires complex synthesis conditions. Moreover, the difference in the hydrolysis rate between the silicon source and titanium source tends to increase the difficulty of titanium insertion into the framework, and it is easy to generate extra-framework Ti species during the synthesis. Here, a high-quality TS-1 zeolite with a large external surface area and free of extra-framework Ti species has been successfully synthesized by using a kind of novel polymer containing titanium and silicon. Due to the high hydrolysis resistance of the polymer reagent, a good matching of the hydrolysis rate between the silicon source and the titanium source is realized during crystallization, which facilitates the incorporation of titanium into the framework. Furthermore, the TS-1 zeolite exhibited excellent catalytic performance in n-hexane oxidation with hydrogen peroxide as the oxidant. This method of synthesizing zeolites from polymers is expected to be widely applied for the synthesis of other titanium-containing zeotype materials.
研究领域:
化学
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材料科学
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催化
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
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2022
·
IF 6.562
Xinchao Liu,Huan Liu,Lihua Chen,Baolian Su,Xinhuan Lu,Qinghua Xia,Dan Zhou
Herein, highly efficient Ti-containing zeolite catalyst (Ti/Al-HSZ) has been prepared by an active catalysis species surface implanting strategy (ACS-SIS) through the combination of precedent acid treatment and subsequent recrystallization. Compared with commercial titanosilicate zeolite catalysts and Ti-HSZ catalyst synthesized by one-step method, Ti/Al-HSZ- c - 3.5d-AT catalyst presents highly enhanced catalytic activity and turnover number values in the epoxidation of linear and cycloalkenes by using 30% H 2 O 2 as oxygen agent under mild reaction conditions. Particularly for the conversion of bulky linear alkene and cycloalkene (1-dodecene and cycloheptene), the catalytic activity of Ti/Al-HSZ- 4M‐3.5d‐AT can attained more than three times than that over Ti-HSZ- 3.5d-AT . Based on systematical comparison and analysis, on one hand, the excellent catalytic performance of Ti/Al-HSZ is ascribed to its unique hollownest morphology that acts as ideal reaction space by providing with plenty of hierarchical porous structure and high external surface, which is beneficial for the diffusion and mass transfer of bulky substrate. On the other hand, the high content of active open Ti species locating on the surface of catalyst is particularly beneficial for the formation of transition state to accelerate the epoxidation reaction. Not only the Ti source utilization rate but also the Ti open incorporated rate of Ti/Al-HSZ- 4M‐3.5d‐AT prepared by ACS-SIS is much higher than that of Ti-HSZ prepared by one-step hydrothermal synthesis route. The effects of acid treatment and recrystallization on the zeolite framework, morphology, chemical composition, and Ti coordination states have been thoroughly discussed. The ACS-SIS is believed to be an effective route to construct excellent solid heterogeneous catalyst to meet the urgent need of green chemistry for sustainable development.
研究领域:
催化
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材料科学
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化学工程
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绿色化学
✓ 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）