CHIRALITY
·
2021
·Vol. 33
·期 10
·710-721
·
IF 2.437
Hui Bai,Lei Chen
Simultaneous separation of the enantiomer and impurities is a huge challenge for the quality control of the chiral drug. In this work, mixed-mode chiral ligand exchange stationary phases (CSPs) modified by octyl and sulfhydryl ligands were prepared by vapor deposition and click chemistry methods. Qualitative and quantitative determination of the prepared CSPs were achieved by Fourier transform infrared spectroscopy, solid-state 13 C CP/MAS NMR, and elemental analysis. The chiral resolution of CSPs was investigated through a comprehensively chromatographic evaluation of various racemates. Besides, the thermodynamic experiment was carried out to elucidate the contribution of hydrophobic ligand to the improvement of chiral recognition and selectivity. Atenolol and its degradation products were analyzed on the synthesized CSPs and compared with the commercial chiral column. A good separation of atenolol enantiomers from its acid and alkaline degradation impurities was simultaneously achieved on the C 8 /L-Hypro CSP. This new CSP is expected to have more applications in the quality control of other chiral drugs.
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Chemistry-An Asian Journal
·
2021
·Vol. 16
·期 19
·2952-2957
·
IF 4.568
Fengwei Zhang,Mengmeng Liu,Qiang Liu,Jingjing Li,Boyang Li,Zhengping Dong
Graphical A facile and in-situ methanol-mediated strategy was proposed to fabricate Pd@ZIF-8 catalyst for efficient and size-selectivity alkenes hydrogenation. In-situ encapsulation of tiny and well-dispersed Pd nanoparticles (Pd NPs) in zeolitic imidazolate frameworks (ZIFs) was firstly achieved using a one-pot and facile methanol-mediated growth approach, in which methanol served as both solvent and a mild reductant. The microstructure, morphology, crystallinity, porosity as well as evolution process of the catalysts were determined by TEM, XRD, N 2 adsorption and UV-vis spectra. Due to the complete encapsulation of such Pd NPs combined with ultrahigh surface area and uniform microporous structure of ZIF-8, the resulting Pd@ZIF-8-60 min nanocomposite exhibited more superior catalytic activity for olefins hydrogenation with TOF of 7436 h −1 and excellent size selectivity than previously reported catalysts. Furthermore, the catalyst displays excellent recyclability for 1-octene hydrogenation and without any loss of the Pd active species.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Xinchao Liu,Jing Wang,Yongde Xia,Xinhuan Lu,Qinghua Xia,Dan Zhou
From the considering of simple synthesis step, low cost, and energy saving, one-step synthesis of hierarchical zeolite without involving additional template has obvious advantages compared with post-synthetic modification or one-step templating methods, by which Ti-containing hollownest structure zeolite (Ti-HSZ) has been successfully synthesized. Herein, the origin of Ti-HSZʼs hollownest structure has been investigated by systematical comparison study between the rotating hydrothermal (RH) and static hydrothermal (SH) synthesis routes. It is found that different synthesis routes not only influence the crystallization but also determine the chemical and physical properties of zeolites. Compared with the catalyst prepared by flower-like precursor with larger size obtained by SH route in 12 days, Ti-HSZ catalyst with smaller size formed by RH route in 3.5 days shows higher catalytic activity for the epoxidation of bulky alkenes with H 2 O 2 . On one hand, the rapid and efficient transports of various reaction species in RH environment has accelerated the crystallization rate greatly; on the other hand, the one-step self-assembly of lamellar MWW crystals has happened to facilitate the formation of hollownest structure with hierarchical pores through intergrowth driven by centrifugal force. The different evolution processes of the Si chemical environments during the early stages of crystallization reflected by the percentage of intrinsic defects origin from the different hydrothermal environments. Highly mixed and dispersed reaction species under RH condition accelerate the uniform of gel concentration, and the condensation of smaller clusters with different orientation direction through frequent contacting under dynamic condition is easy to happen to form bigger clusters, which is the basis for the further crystal intergrowth. In contrast, the relatively inhomogeneous gel environments under SH condition has led to the increase of intrinsic defects in the solid phases, and bigger clusters tend to be formed by the condensation of smaller ones with the same orientation direction. This work will be instructive not only for the understanding of zeolites’ crystallization mechanism, but also for the design and synthesis of zeolite materials with unique morphology characteristics.
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EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Yejun Luo,Suqin Deng,Zheng Li,Lijiu Cao,Yuan He,Yufang Chen,Tao Jin
Hydrophobic modified cotton filter fabric is a key material in the chemical industry, as it is used in common industrial filtration and precision separation processes. Most studies have focused on improving the hydrophobicity of cotton filter fabric. However, the hydrophobic durability, which is the most critical factor that determines the application scope of the material, remains unaddressed. Herein, we report that CS 2 activation and subsequent 1-octadecene graft copolymerization via ARGET-ATRP of the cotton filter fabric leads to a modified material that is largely superior to the traditional cotton filter fabric. The modified cotton filter fabric exhibits high hydrophobicity, with an initial water contact angle of 141.0° and excellent hydrophobic durability, as demonstrated by the residual water contact angle of 126.7° after a 150 min droplet holding time. Moreover, the modified hydrophobic sample fabric was resistant to a variety of physical stresses and chemicals, maintaining its hydrophobic properties following multiple resistance tests, such as immersion in oily water for 10 days, immersion in organic solvents for 72 h, or when subjected to UV radiation for 24 h.
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APPLIED ORGANOMETALLIC CHEMISTRY
·
2020
·Vol. 35
·期 1
·e6027
·
IF 3.14
Zinan Dai,Zehao Yu,Ying Bai,Jiayun Li,Jiajian Peng
A simple method for the hydrosilylation of olefins by using air-stable cobalt catalysts is developed. The catalyst system is composed of simple, cheap, and readily available cobalt(II) salts and well-defined terpyridine derivatives as cocatalysts or ligands, and the hydrosilylation processes can be processed smoothly under mild conditions without either Grignard reagents or NaHBEt 3 as activator.
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CATALYSIS LETTERS
·
2021
·Vol. 151
·期 9
·2638-2646
·
IF 3.186
Li Xiao,Qin Tingting,Li Liusha,Wu Bo,Lin Tiejun,Zhong Liangshu
Abstract A green route for one−pot synthesis of acetals by tandem hydroformylation−acetalization of olefins using supported Rh−based catalysts was developed. Experimental results demonstrated that suitable Rh loading (1 wt%) with appropriate reaction temperature (120 °C) and reaction time (8 h) were favorable for the formation of acetals, and a high acetals selectivity of 94.6% was achieved. More importantly, the selectivity to valuable linear products was enhanced in this tandem catalysis. Based on the catalytic mechanism study, highly dispersed RhO x nanoparticles and abundant acid sites on the supports were responsible for the hydroformylation and acetalization, respectively. Graphical abstract One-pot synthesis of acetals directly from olefins with high selectivity was achieved over heterogeneous bifunctional catalysts via tandem hydroformylation-acetalization.
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LANGMUIR
·
2020
·
IF 3.557
Liang Zhao,Changzhen Yin,Ting Long,Peng Hu,Zhenyu Yang
Colloidal perovskite nanocrystals (NCs) have shown promise in visible and near-infrared light emission compared with conventional quantum dots because of their sharp and highly efficient emission. Light-driven halide exchange offers high degrees of tunability of perovskite NC composition and photoluminescence properties. A remaining challenge is the incomplete change between bromide and chloride due to the presence of radical quenchers. Herein, an optimized in situ halide exchange method of perovskite NCs is reported. Chloroform is used as the solvent and the precursor to effectively generate halide radicals and ions under ultraviolet light irradiation in an inert atmosphere. This strategy achieves complete crystal transformation in colloidal perovskite NCs such as CsPbBr3-to-CsPbCl3 and Cs4PbBr6-to-CsPbCl3. The exchange reaction rate can be further tuned by the presence of B-site dopants such as Zn2+ and Ce3+. The dopant cations are partially remained in the exchanged perovskite NCs, indicating the predominance of thermodynamic control in the crystal transformation.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Zhijun Li,Honghong Li,Dundong Yuan,Leipeng Leng,Mingyang Zhang,Minghui Di,J. Hugh Horton,Jun Wang,Litao Sun,Weiwei Sun
Exploring the interaction between metal and support is of great importance in enhancing the catalytic performance and deepening the mechanistic understanding of single atom catalysis. Here we describe a photoinduction method to construct atomically dispersed palladium atoms supported over defect-containing boehmite (γ-AlOOH) nanoleaf with a palladium loading of 0.32 wt%. The existence of singly dispersed palladium atoms is confirmed by spherical aberration correction electron microscopy, extended X-ray absorption fine structure measurement, and CO-absorbed diffuse reflectance infrared Fourier transform spectroscopy. This catalyst shows excellent catalytic efficiency in trans -stilbene epoxidation to yield trans -stilbene oxide (TOF: 416 h −1 ; conversion: 84 %; selectivity: 99 %), along with excellent recyclability and scalability. In addition, various aromatic olefins were successfully transformed into the corresponding epoxides with high selectivity and excellent yield. DFT study further reveals that the high catalytic activity originates from under-coordinated single palladium atoms in the defect-containing γ-AlOOH in a unique coordination environment. This lays the foundation for the facile creation of single atom catalysts and sheds light on the possibility for scale-up production.
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NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 27
·11968-11976
·
IF 3.591
Xingyu Yang,Xu Li,Jinxiang Dong
The epoxidation of linear-chain α-olefins over heterogeneous catalysts is still challenging, while epoxides as versatile raw intermediates are highly desirable. Here, we describe the facile preparation of farringtonite, obtained via the calcination of commercial anhydrous trimagnesium phosphate, and its novel application in the epoxidation of olefins. Farringtonite was characterized via XRD, FT-IR, SEM-EDS, and CO2-TPD studies. The CO2-TPD data exhibited that farringtonite mainly possesses medium-base sites. The catalytic activity of farringtonite was optimized via adjusting different parameters, including the solvent, temperature, amount of H2O2, farringtonite loading, stirring rate, and so on, using 1-octene epoxidation as the model reaction and 30% H2O2 as the oxidant. The results from 1-octene epoxidation indicated that the farringtonite catalyst exhibited efficient catalytic activity, with high conversion of up to 85.2% and epoxide selectivity of 87.6% under the optimal conditions. In addition to 1-octene, 1-decene and 1-heptene were also used, achieving good-to-excellent conversions with high selectivities. In addition, farringtonite could be recycled four times with the preservation of its high catalytic activity. From a mechanistic standpoint, the in situ generation and consumption of Payne's reagent is responsible for the epoxidation reaction. Therefore, farringtonite serves as an excellent catalyst for the epoxidation of α-olefins.
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FUEL
·
2021
·
IF 6.609
Xiaoyu Yao,Tianyi Luo,Tao Yin,Shifeng Lou,Xuan Meng,Naiwang Liu,Li Shi
To date, the scalable exfoliation of the resource-rich montmorillonite (MMT) into high-quality few-layered nanosheets still remains a grand challenge. Herein, a simple, nontoxic, and efficient strategy is proposed to exfoliate layered MMT into mono-layered MMT nanosheets (MMTNS) via thermal expansion gas-assisted exfoliation method. The essence of this method is that the high temperature expands the interlayer distance while weakens the van der Waals force between interlayer of bulk MMT and then the liquid nitrogen (L-N 2 ) penetrated the interlayers can be quickly vaporized to exfoliate the MMT. With a high mass yield of 18–20%, the prepared MMTNS has a thickness around 1.9 nm and a reasonable aspect ratio (lateral dimension of 0.5 µm-3 µm). Meanwhile, no impurities were introduced during the whole procedure. Additionally, the exfoliated MMTNS with high specific surface area (402 m 2 g −1 ) and more exposed acid sites is further applied for the removal of trace olefins from aromatics, the result shows higher olefin conversion (76.97%) than its parent bulk phase (50.66%). The possible reaction mechanism of removing olefins from aromatics was further proposed and investigated by gas chromatography-mass spectrometry (GC–MS).
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 24
·7034-7044
·
IF 5.726
Liwei Zhang,Huaike Zhang,Zhiqiang Chen,Qiang Ning,Suyao Liu,Jie Ren,Xiaodong Wen,Yong-Wang Li
To correlate the relationship between the Al distribution and the catalytic performance of long-chain olefin aromatization, several ZSM-5 zeolites with different Al locations and proximities were prepared via adjusting the hydrothermal synthesis conditions. Characterization by XRD, SEM and N2-adsorption indicated that all the as-prepared ZSM-5 zeolites exhibited high crystallinities, uniform morphologies and open channels. However, a great difference in the framework Al (AlF) positions was observed by 27Al MAS NMR and UV-vis-DRS of Co(II) ions, thus leading to the distinct acidity of various zeolites as determined by NH3-TPD and Py-IR. In 1-octene aromatization reaction, ZSM-5 catalysts exhibited significantly different catalytic performances and reaction pathways, which were closely related to the types and locations of the AlF atoms. The ZSM-5 zeolite catalyst with the most abundant single Al sites exhibited the lowest aromatics selectivity, while Al pairs in the framework were more favorable to the formation of aromatics. Moreover, the product distribution revealed that the Al pairs in the channel intersections of the ZSM-5 zeolite were responsible for the improved selectivity to heavy aromatics due to the fewer space restrictions; however, the Al pairs in the sinusoidal and straight channels with severe size restrictions suppressed the generation of bigger aromatics on the Al sites. This result provided a new potential method for precisely tailoring the catalytic selectivity in olefin conversion and upgrading the Fischer–Tropsch oil.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 10
·7628-7636
·
IF 3.442
Lu Xuegang,Chen Changhao,Wen Xiaoxiang,Han Ping,Jiang Wenfeng,Liang Gongying
Highly charged monodisperse magnetite/polystyrene colloidal particles are successfully synthesized by using a miniemulsion polymerization method. The particles, with high saturation magnetization (M s ≈ 38.6 emu g −1 ), display high sensitivity to the magnetic field and can self-assemble into periodically ordered colloidal structure in aqueous solution, thus diffract light strongly, under magnetic induction. By changing the strength of magnetic field, the position of reflection peaks can be reversibly tuned in the range of 420–720 nm, covering almost the entire visible light range. After adding 1.5 wt.% of acid black 210 into the colloidal suspension, the color saturation and brightness of the colloids are significantly improved. As-prepared magnetically responsive colloidal particles have great potential to be used in color display, biosensors, anti-counterfeiting, camouflage, pigments and dyes.
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