MICROPOROUS AND MESOPOROUS MATERIALS
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2020
·
IF 4.551
Tingting Qi,Jing Shi,Xishuo Wang,Kun Dong,Yong Luo,Jiawei Teng,Guang-Wen Chu,Hai-Kui Zou,Baochang Sun
Hierarchical (micro/mesopore) ZSM-5 zeolites were hydrothermally synthesized in a rotating packed bed (RPB) which substantially enhances micromixing for the high viscosity reaction system. Herein, the effects of four operating processes with different micromixing intensity on nucleation/crystal growth process as well as physicochemical properties of ZSM-5 zeolites were investigated. Results indicate that enhancing micromixing by RPB in the zeolite synthesis could facilitate the formation of Al sites and shorten the nucleation and crystallization period. ZSM-5 samples prepared by RPB exhibit hierarchical structure, smaller average particle size, more uniform particle size distributions , larger specific surface areas, higher catalytic stability as well as more acid sites than those obtained by (stirring tank reactor) STR. While adopting the ZSM-5 samples prepared by RPB for catalyzing C4-olefin cracking reaction, the conversion of C4-olefin and yield of propylene are higher than those obtained by STR.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Zhao Jiang,Xiang Gong,Shuyi Guo,Yanxin Bai,Tao Fang
The NECZ/12H-NECZ (N-ethylcarbazole/dodecahydro-N-ethylcarbazole) system is regarded as the most potential liquid organic hydrogen carrier. However, the low activity, selectivity of NECZ and high cost of catalysts for the dehydrogenation reaction restrict its efficiency and commercial applications. In this work, a series of bimetallic Pd-M(M = Cu, Ni)/SiO 2 catalysts were prepared and employed to enhance catalytic activity and selectivity of NECZ for the 12H-NECZ dehydrogenation reaction. Pd 3 Ni 1 /SiO 2 exhibited high catalytic performance with 100% conversion, 91.1% selectivity of NECZ and 5.63 wt% hydrogen release amount at 453 K, 101.325 kPa for 8 h. The TOF (turnover frequency) of Pd 3 Ni 1 /SiO 2 is enhanced by 42.4% compared with Pd/SiO 2 . Combined with the characterization analysis, it was found that adjusting the alloying degree or the alloy phase in the PdCu and PdNi bimetallic catalysts could significantly enhance the dehydrogenation activity and selectivity, which were dependent on the component of bimetallic catalysts . This work may provide theoretical guidance for designing the efficient and low-cost bimetallic catalysts for the dehydrogenation of 12H-NECZ, which could boost the commercial applications of liquid organic hydrogen carriers.
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Nature Communications
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2020
·Vol. 11
·期 1
·1-11
·
IF 12.121
Xie Junyao,You Xueqiu,Huang Yuqing,Ni Zurong,Wang Xinchang,Li Xingrui,Yang Chaoyong,Zhang Dechao,Chen Hong,Sun Huijun,Chen Zhong
Magnetic resonance (MR) technology has been widely employed in scientific research, clinical diagnosis and geological survey. However, the fabrication of MR radio frequency probeheads still face difficulties in integration, customization and miniaturization. Here, we utilized 3D printing and liquid metal filling techniques to fabricate integrative radio frequency probeheads for MR experiments. The 3D-printed probehead with micrometer precision generally consists of liquid metal coils, customized sample chambers and radio frequency circuit interfaces. We screened different 3D printing materials and optimized the liquid metals by incorporating metal microparticles. The 3D-printed probeheads are capable of performing both routine and nonconventional MR experiments, including in situ electrochemical analysis, in situ reaction monitoring with continues-flow paramagnetic particles and ions separation, and small-sample MR imaging. Due to the flexibility and accuracy of 3D printing techniques, we can accurately obtain complicated coil geometries at the micrometer scale, shortening the fabrication timescale and extending the application scenarios.
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PubMed
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Frontiers of Chemical Science and Engineering
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2020
·Vol. 14
·期 6
·1018-1028
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IF 3.552
Zeng Jiehui,Zeng Jianxian,Zhou Hu,Liu Guoqing,Yuan Zhengqiu,Jian Jian
An ion-imprinted sorbent (IIP) was prepared by using Ni 2+ as template, 3-[2-(2-aminoethylamino) ethylamino] propyl-trimethoxysilane as functional monomer, and silica gel as carrier. The adsorption performance of IIP towards Ni 2+ was investigated. IIP showed a higher adsorption capacity than that of non-imprinted sorbent, and it also exhibited high selectivity for Ni 2+ in the presence of Cu 2+ and Zn 2+ ions. Then, IIP was used to form a dynamic membrane onto the surface of ceramic membrane for treatment of electroplating wastewater containing Ni 2+ . Compared with ceramic membrane, IIP dynamic membrane had much higher steady membrane flux, and also rejected Ni 2+ to obtain a lower concentration of Ni 2+ in the permeate fluid. Perhaps it is suitable for future practice applications.
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MOLECULES
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2020
·Vol. 25
·期 4
·914
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IF 3.267
Ligeng Wang,Chun Feng,Yan Zhang,Jun Hu
The regioselective mono-bromination of phenols has been successfully developed with KBr and ZnAl–BrO3−–layered double hydroxides (abbreviated as ZnAl–BrO3−–LDHs) as brominating reagents. The para site is much favorable and the ortho site takes the priority if para site is occupied. This reaction featured with excellent regioselectivity, cheap brominating reagents, mild reaction condition, high atom economy, broad substrate scope, and provided an efficient method to synthesize bromophenols.Keywords:phenol;bromination;regioselecitvity
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Journal of Food Measurement and Characterization
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2020
·Vol. 14
·期 4
·2134-2144
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IF 1.648
Huang Xin,Wang Li,Chen Jingyu,Jiang Chengyu,Wu Shijia,Wang Hongxin
Tea polyphenols (TPPs), as the most important functional component in tea extract, are easily contaminated by many heavy metals during tea processing, transportation and storage. TPPs with heavy metals can cause serious health problems and economic losses. In this study, to efficiently remove heavy metals from TPPs without affecting their active compounds and antioxidant functions, we prepared the amino-functionalized modified silica gel (AFSG) to remove Pb, Cu and Cd from TPPs, and determined removal rate of heavy metals, total polyphenolic content (TPC) and antioxidant activity of TPPs before and after adsorption. The static adsorption experiments showed that the adsorption isotherms were consistent with Langmuir model, in which the maximum sorption capacities of Pb, Cu and Cd were 140.23, 100.75 and 48.03 mg/g (25 °C, pH 5.0), respectively. Compared with before adsorption, the contents of Pb, Cu and Cd in 3 TPPs samples decreased significantly after adsorption on AFSG column (p < 0.01). However, the TPC and antioxidant capacity of the 3 TPPs samples had no significant effect before and after adsorption (p > 0.05). Meanwhile, the desorption and regeneration experiment showed that after 6 times of cyclic adsorption, the removal ability of Pb, Cu and Cd in TPPs by AFSG column could still reach 98.1%, 99.59% and 99.78%, respectively. Therefore, these results suggested that AFSG column could effectively remove heavy metals from TPPs without affecting the TPC and its antioxidant activity, it has potential applications in the removal and detection of heavy metals in TPPs.
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Nano Research
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2021
·Vol. 14
·期 11
·4347-4355
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IF 8.897
Lu Xiaowen,Guo Chunmu,Zhang Mingyang,Leng Leipeng,Horton J. Hugh,Wu Wei,Li Zhijun
Chemoselective hydrodeoxygenation of vanillin is of great importance in converting biomass into high value-added chemicals. Herein, we describe a facile photochemical route to access palladium single atoms and clusters supported on silicoaluminophosphate-31 (SAPO-31) as a highly active, chemoselective, and reusable catalyst for hydrodeoxygenation of vanillin. Characterizations by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and CO-absorbed diffuse reflectance infrared Fourier transform spectroscopy reveal the atomically dispersed palladium single atoms and clusters are loosely bonded and randomly dispersed, without forming strong palladium-palladium metallic bonding, over the SAPO-31 support. This catalyst, with a full metal availability to the reactants, exhibits exceptional catalytic activity (TOF: 3,000 h −1 , Yield: > 99%) in the hydrodeoxygenation of vanillin toward 2-methoxy-4-methylphenol (MMP) under mild conditions (1 atm, 80 °C, 30 min), along with excellent stability, scalability (up to 100-fold), and wide substrate scope. The superior catalytic performance can be attributed to the synergistic effect of the positively charged palladium single atoms and fully exposed clusters, as well as the strong metal-support interactions. This work may offer a new avenue for the design and synthesis of fully exposed metal catalysts with targeted functionalities.
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JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
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2021
·Vol. 32
·期 8
·1598-1606
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IF 1.838
Zhang Yangyang,Shao Chuan,Qin Dongling,Yang Gang
Solid acid-catalyzed dehydration of fructose to produce 5-hydroxymethylfurfural (5-HMF) has been a hotspot in biomass conversion research in recent years. In this study, a novel SAPO-34-based catalyst was prepared by consecutive steps of titanium doping, sulfuric acid impregnation, and sulfonic acid functionalization. Characterization of the catalyst with X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), BrunauerEmmett-Teller (BET), inductively coupled plasma optical emission spectrometer (ICP-OES), and acid-base titration revealed different pore structures and more acid content compared to SAPO-34. The catalyst was applied to the preparation of 5-HMF by dehydration of fructose, and the maximum yield (74.0%) of 5-HMF was obtained by reacting in dimethyl sulfoxide (DMSO) at 170 °C for 50 min. In addition, the applicability of the catalytic system to other substrates and the stability of the catalyst after five cycles were investigated, which are valuable for further probing on the concerned aspects.
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CATALYSIS LETTERS
·
2021
·Vol. 152
·期 5
·1372-1385
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IF 3.186
Qiu Baocheng,Zhang Yakun,Zhang Yi
The rapid deactivation caused by coke deposits is the major obstacle to the ethane aromatization of Zn-based catalysts. We have successfully synthesized a Zn-embedded inside HZSM-5 crystal catalyst (Zn@HZSM-5) by hydrothermal synthesis using preformed Zn/SiO 2 as the only silicone source. Based on various characterization results, including in situ etching XPS, operando DRIFTS, as well as NMR, it is found that Zn(OH) + and [Zn–O–Zn] 2+ species are active sites for ethane aromatization for zinc-based catalysts, and their dynamic transformation significantly changes reaction performance of ethane dehydrogenation. For the Zn/HZSM-5 catalyst, the existence of a large number of [Zn–O–Zn] 2+ species causes higher initial ethane conversion and higher selectivity of aromatics, resulting in a large amount of coke deposits. Moreover, [Zn–O–Zn] 2+ species on the Zn/HZSM-5 catalyst fast transit to Zn(OH) + species and subsequently form the sintered ZnO species, leading to rapid deactivation. For the Zn@HZSM-5 catalyst, the embedded structure contributes to forming more Zn(OH) + species and delays the transformation of the Zn(OH) + species to [Zn–O–Zn] 2+ species, resulting in slowly increased selectivity of aromatics during the reaction. Therefore, the Zn@HZSM-5 catalyst realizes stable ethane conversion with dynamic selectivity. Graphic Abstract
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Crystals
·
2021
·Vol. 11
·期 10
·1247
·
IF 2.589
Changsheng Zhang,Kai Fan,Ge Ma,Chi Lei,Wei Xu,Jie Jiang,Bing Sun,Hongxing Zhang,Yunfeng Zhu,Song Wen
Hierarchical zeolites attract people’s attention due to their enhanced mass transfer properties in catalytic reactions. The research over obtaining these zeolites in green and efficient methods is of great significance for the current post-treatments and templating strategies tend to be costly for hierarchical zeolite synthesis. In this research, nanosized mesoporous ZSM-5 (SN-ZSM-5) zeolites have been synthesized without the addition of mesoscale templates under highly concentrated conditions. The physicochemical characteristics were systematically investigated by XRD, SEM, N2 sorption, TEM, and NMR. The SEM images showed ZSM-5 crystals with sizes between 50–110 nm were obtained. N2sorption and high-resolution TEM images gave direct evidence for the hierarchical structure of SN-ZSM-5. The forming mechanism for the hierarchical structure was proposed that the etching effect of the highly alkaline environment for the starting gels played a critical role in the formation of hierarchical structure. Catalytic tests in methanol-to-olefins (MTO) showed the SN-ZSM-5 performed a longer catalyst lifetime and higher propylene selectivity than the conventional ZSM-5 zeolites (C-ZSM-5) obtained from a traditional hydrothermal method. The features of hierarchical structure in the SN-ZSM-5 crystals and the sustainability for synthesis method could show a promising choice for wide applications of these SN-ZSM-5 zeolites in the future.Keywords:ZSM-5 zeolite;efficient synthesis;hierarchical;nano crystals
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JOURNAL OF ORGANIC CHEMISTRY
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2019
·
IF 4.745
Shou-Jie Shen,Xiao-Li Du,Xiao-Li Xu,Ming-Gang Zhao,Jin-Yan Liang
The regioselective N-addition/substitution reaction between α-alkylidene pyrazolinones and propargyl sulfonium salts has been developed to construct functionalized allylthio-containing pyrazolones with moderate to excellent yields. α-Alkylidene pyrazolinones act as N-nucleophilic agents which are distinguished from reported C-nucleophilic reactions. Excellent regioselectivity, readily available starting materials, the broad range of substrates, gram-scale synthesis, and simple operation illustrate the synthetic advantages of this new reaction pathway.
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RSC Advances
·
2019
·Vol. 9
·期 60
·34912-34925
·
IF 3.049
Shou-Jie Shen,Xiao-Li Du,Xiao-Li Xu,Yue-Hua Wu,Ming-gang Zhao,Jin-Yan Liang
The first sequentially combined inorganic base promoted N-addition/[2,3]-sigmatropic rearrangement reaction of α-alkylidene pyrazolinones and propargyl sulfonium salts has been reported to construct homoallyl sulfur-containing pyrazolones with moderate to excellent yields. α-Alkylidene pyrazolinones function as N-nucleophilic agents distinguished from the reported C-addition reactions. Propargyl sulfonium salts were first involved in the [2,3]-sigmatropic rearrangement protocol differentiated from the well-established annulation reactions. The excellent regioselectivity, the broad scope of substrates, gram-scale synthesis and convenient transformation embody the synthetic superiority of this cascade process.
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