CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2016
·Vol. 95
·期 6
·1109-1116
·
IF 1.066
Jianqiang Zhang,Jian Luo,Jun Gao,Dianhua Liu
Catalytic hydrogenation of acetic acid to ethanol was investigated in a fixed-bed micro-reactor with calcium silicate-modified platinum-tin catalyst at mild reaction condition. The modified catalyst exhibited excellent performance for the ethanol synthesis process at relatively low pressure. According to the results of H 2 -pulse chemisorption experiments, the introduction of calcium silicate promoted the dispersion of platinum particles. The NH 3 -TPD and H 2 -TPR results showed the decrease of acid content on catalyst surface and the enhancement of reducibility after the CaSiO 3 modification. Additionally, the results of XPS indicated that Sn (0) was emergent and Pt (2+) was sharply decreased after reduction. Both the H 2 -TPR and XPS results supported the formation of Pt-Sn alloy during the reduction process at 623 K. The Pt-Sn alloy changed the electron density and benefited the free hydrogen dissociation and hydrogenation. The enhancement of reaction temperature and pressure both promoted acetic acid conversion. The kinetic model of power-function type was established to describe the process of hydrogenation. The results of residual analysis confirmed that the raised kinetic model for acetic acid to ethanol reaction was suitable.
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
POLYMER DEGRADATION AND STABILITY
·
2018
·
IF 3.193
Lidong Feng,Songyang Feng,Xinchao Bian,Gao Li,Xuesi Chen
In order to obtain the mechanisms of the pyrolysis reaction that poly (lactic acid) (PLA) gives lactide in the presence of Sn, the four types of low molecular weight PLAs (L-PLA) with different end-groups were prepared, including HO-L-PLA-COOH, R-L-PLA-OH, R-L-PLA-COOH, and R-L-PLA-R, and depolymerized by thermogravimetry at different heating rates. As for the pyrolysis reactions of the L-PLAs, their activation energy ( E a ) were estimated by the several isoconversional model-free methods and their kinetic models were also explored by the Malek method. The random degradation behavior of L-PLAs was determined by the plots of ln { − ln [ 1 − ( 1 − w ) 0.5 ] } vs. 1/T for experimental data from TG for L-PLAs and model reactions. The experimental results showed that the E a values and the possible kinetic models for the pyrolysis reactions of the L-PLAs were different due to the different end-groups and thereof the mechanisms for the pyrolysis reactions of PLA that give lactide were proposed under the catalysis of Sn. The pyrolysis reactions of R-L-PLA-OH and R-L-PLA-R trend to be controlled by a single kinetic model. The pyrolysis reactions of HO-L-PLA-COOH and R-L-PLA-COOH are more complex and controlled by not less than two kinetic processes. The pyrolysis reaction of PLA selectively produces lactide through the unzipping and intramolecular transesterification reactions, including the backbiting reaction caused by the Sn-carboxylate and Sn-alkoxide chain ends, which are directly formed from the hydroxyl and carboxyl end-groups of PLA, and the lactide selective elimination at the random position of the polymeric backbone.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
AICHE JOURNAL
·
2025
·
IF 4
Ziqi Bian,Minhao Chen,Xiaohu Ge,Ningchao Zhu,Yueqiang Cao,Hao Jiang,Jing Zhang,Gang Qian,Xinggui Zhou,Xuezhi Duan
Designing and fabricating uniformly dispersed non-precious metal active sites with tuned geometric configurations and local coordination environments for the selective conversion of functional groups to desired products is of great importance but remains challenging in industrial catalytic processes. In this work, we propose a straightforward method for synthesizing the Co 3 Sn 2 intermetallic catalyst through the structural conversion of layered double hydroxide precursors, thereby constructing suitable Sn-modified Co active sites and an optimized catalytic environment for propyne semihydrogenation. Characterizations using x-ray diffraction, high-resolution transmission electron microscopy, and x-ray absorption spectroscopy characterizations are combined to identify the formation of P6 3 /mmc Co 3 Sn 2 intermetallic phase. Catalytic performance tests show that the Co 3 Sn 2 catalyst achieves 95.0% propylene selectivity with nearly complete propyne conversion. Temperature-programmed surface reaction and desorption measurements combined with theoretical calculations demonstrate that the good selectivity is driven by the facile desorption of propylene from Sn-modified Co sites rather than its further hydrogenation.
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
ACS Catalysis
·
2015
·
IF 9.312
Ruiyan Sun,Mingyuan Zheng,Jifeng Pang,Xin Liu,Junhu Wang,Xiaoli Pan,Aiqin Wang,Xiaodong Wang,Tao Zhang
The direct hydrogenolysis of cellulose represents an attractive and promising route for green polyol production. Designing a catalyst system that could control the selectivity of polyols of this process is highly desirable. In this work, we realized the selectivity-switchable production of ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG) by using Sn species with different valences in combination with Ni catalysts. The combination of Ni/AC and metallic Sn powders exhibited a superior activity toward EG (57.6%) with up to 86.6% total polyol yield, while the combination of Ni/AC and SnO favored the formation of 1,2-PG (32.2%) with a 22.9% yield of EG. The Sn species in NiSn alloy in situ formed from metallic Ni and Sn powders was found to be the active sites for the high selectivity of EG as evidenced by control experiments and characterizations including X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, energy dispersive X-ray mapping, and 119Sn Mössbauer spectroscopy. The effects of Sn loading, reaction temperature, reaction time, and the concentration of cellulose were investigated for Ni/AC + Sn powders. Because of the formation of NiSn alloy, the Ni–Sn catalyst showed good stability during repeated use. Experimental results disclosed that the Sn species with different valence possessed distinct catalytic functions. Both SnO and the alloyed Sn species could catalyze the retro-aldol condensation of glucose to glycolaldehyde, and meanwhile, SnO was also active for the isomerization of glucose to fructose. Therefore, controlling the glycol products distribution could be realized using SnO or the alloyed Sn species as catalysts.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Shuai Fan,Huiyuan Cheng,Manman Feng,Xuemei Wu,Zihao Fan,Dongwei Pan,Gaohong He
The conversion of CO 2 electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle. Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn catalyst to overcome the limit of electron transfer and CO 2 adsorption capacity of Sn. Hierarchically porous structure of Sn doped carbonized ZIF-8 is controlled by hydrothermal and carbonization conditions, which induces much higher specific surface area than that of the commercial Sn nanoparticle (1003.174 vs. 7.410 m 2 ·g −1 ). The shift of nitrogen peaks in X-ray Photoelectron Spectroscopy spectra indicates interaction between ZIF-8 and Sn, which induces the shift of electron cloud from Sn to the chemical nitrogen to enhance conductivity and regulate electron transfer from catalyst to CO 2 . Lower mass transfer resistance and Warburg resistance are investigated through EIS, which significantly improves the catalytic activity for CO 2 reduction reaction (CO 2 RR). Onset potential of the reaction is reduced from −0.74 V to less than −0.54 V vs. RHE. The total Faraday efficiency of HCOOH and CO reaches 68.9% at −1.14 V vs. RHE, which is much higher than that of the commercial Sn (45.0%) and some other Sn-based catalyst reported in the literature.
研究领域:
材料科学
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环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2020
·
IF 0
Yang Gao,Haijun Dong,Licheng Liu,Yingfeng Yu,Zhengming Tang,Chenyan Bai,Thorsten Schmidt,Yanli Feng,Hongyu Chen
For many applications, polyurethanes (PUs) need to have a fast curing speed and long pot life. Latent catalysts are seen to be one of the approaches that can fulfill this need. In this article, we have synthesized a series of copolymers with n-alkyl acrylates and a reactive tin catalyst, dibutyltin maleate, by conventional free radical polymerization using azodiisobutyronitrile (AIBN) as an initiator and dodecanethiol as a chain transfer agent. The copolymers with crystalline side chains were characterized by gel permeation chromatography (GPC), 1H NMR, 13C NMR, differential scanning calorimetry (DSC), and ion chromatography. The tin-containing copolymers showed high crystallinity. The melting temperature of the copolymers decreases slightly with the decrease of molecular weight (Mw), while the crystallinity remains almost unchanged. The catalytic performance and latency of the crystalline copolymers with different particle sizes were characterized by rheological measurement and Fourier transform infrared spectroscopy (FTIR). The crystalline copolymers showed quite good latency at 30 °C and high reactivity above the melting point. Both the particle size and the Mw of the copolymers had effects on the latency of crystalline catalysts. The PU adhesive with copolymers showed a higher peel strength at the initial stage than the noncatalyzed one and comparable final properties as compared with the samples with dibutyltin dilaurate and dibutyltin maleate.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
Precision Chemistry
·
2024
·
IF 0
Hui Ye,Lina Cao,Minghui Gu,Han Nie,Qingqing Gu,Bing Yang,Yunxing Bai,Qinxue Nie,Weixin Huang,Junling Lu
Propane dehydrogenation (PDH), an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency, has recently attracted extensive attention. The severe deactivation of Pt-based catalysts through sintering and coking remains a major challenge in this high-temperature reaction. The introduction of Sn as a promoter has been widely applied to improve the stability and selectivity of the catalysts. However, the selectivity and stability of PtSn catalysts have been found to vary considerably with synthesis methods, and the role of Sn is still far from fully understanding. To gain in-depth insights into this issue, we synthesized a series of PtSn/SiO2 and SnPt/SiO2 catalysts by varying the deposition sequence and Pt:Sn ratios using atomic layer deposition with precise control. We found that PtSn/SiO2 catalysts fabricated by the deposition of SnOx first and then Pt, exhibited much better propylene selectivity and stability than the SnPt/SiO2 catalysts synthesized the other way around. We demonstrate that the presence of Sn species at the Pt-SiO2 interface is of essential importance for not only the stabilization of PtSn clusters against sintering under reaction conditions but also the promotion of charge transfers to Pt for high selectivity. Besides the above, the precise regulation of the Sn content is also pivotal for high performance, and the excess amount of Sn might generate additional acidic sites, which could decrease the propylene selectivity and lead to heavy coke formation. These findings provide deep insight into the design of highly selective and stable PDH catalysts.
研究领域:
化学工程
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催化化学
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材料科学
✓ 已验证
DOI
JOURNAL OF MATERIALS SCIENCE
·
2014
·Vol. 49
·期 16
·5772-5781
·
IF 2.305
Shi Junjun,Zhou Yuming,Zhang Yiwei,Zhou Shijian,Zhang Zewu,Kong Jie,Guo Mingpeng
Magnesium (Mg)-modified mesoporous alumina with different type and content of Mg was prepared and then used as the support for platinum-tin catalyst in propane dehydrogenation. It was found that the property of Mg in Al 2 O 3 varied with the way of the addition of Mg precursors. For the grafted Mg species, the connection between Al 2 O 3 and Mg was increased by the forming of Mg–O–Al bonds in the inner surface of Al 2 O 3 pore. While for the traditional impregnation, Mg was attached loosely to the outer Al 2 O 3 surface by the aggregation of MgO. Moreover, modifying the internal framework of Al 2 O 3 by suitable content of Mg can enhance the interaction between Sn and support, leading to more amounts of tin in their oxidized states, which was beneficial to enhance the interaction of Pt with SnO x species. As a result, agglomerations of metallic particles were suppressed and the catalyst exhibited the best catalytic performance in terms of activity and stability.
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
CATALYSIS COMMUNICATIONS
·
2023
·
IF 3.7
Zhao Yang,Yan Xiong,Ting Li,Zhiqing Yang,Bing Hui Chen
Carbon supported Ru-Sn bimetallic catalyst shows excellent performance in room-temperature hydrogenation of acetone, 100% acetone conversion with 100% product selectivity to isopropyl alcohol can be achieved within a short reaction time. Catalyst structure-function relationship reveals a synergetic behavior between Ru and Sn sites, demonstrating the essential correlation between Sn/Ru atomic ratio and the resultant variation in catalytic performance. Room temperature hydrogenation of 4-heptanone was also studied, verifying the consistency of the established structure-function relationship in ketones hydrogenation reactions.
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
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
·
2014
·
IF 3.679
Lipeng Zhou,Lin Wu,Hongji Li,Xiaomei Yang,Yunlai Su,Tiangliang Lu,Jie Xu
A facile and efficient method to improve the selectivity of methyl lactate (MLA) in the chemical conversion of glucose in methanol catalyzed by homogeneous Lewis acid was established. The yield of MLA was efficiently improved through controlling the acidity of the reaction solution by neutralization of protons generated from the hydrolysis/methanolysis of SnCl 4 . The mechanism of glucose conversion to MLA catalyzed by SnCl 4 -NaOH was explored. The effects of the concentration of catalyst and substrate and the reaction temperature and time were systematically studied. The catalyst system of SnCl 4 -NaOH can efficiently convert glucose, fructose, and sucrose to MLA with yields of 47%, 57%, and 51% at 160 °C for 2.5 h, respectively. The catalyst can be regenerated and reused at least three times in the conversion of glucose to MLA without significant loss of activity and selectivity.
研究领域:
化学工程
·
催化化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Qingqing Li,Yanxing Zhang,Xurui Zhang,Hongqiang Wang,Qingyu Li,Jiawei Sheng,Jin Yi,Yuyu Liu,Jiujun Zhang
Electrochemical reduction of CO2 to useful low-carbon fuels can not only mitigate global warming problems but also be used for energy storage. For efficient CO2 electrochemical reduction in mild conditions, high-performance catalysts are required. In this work, the electrodeposition of bismuth, tin, or both on copper sheets to fabricate Sn/Cu, BiSn/Cu, Bi2Sn/Cu, Bi3Sn/Cu, Bi4Sn/Cu, and Bi/Cu electrodes was conducted, and the electrodes were used as catalysts in CO2 reduction. Experimental results show these electrodes have high activity, stability and selectivity toward CO2 reduction to formic acid. A maximum Faraday efficiency of 90.4% for formic acid production can be achieved when using a Bi/Cu electrode. The mechanism catalyzed by such electrodes is also proposed for fundamental understanding and is clearly explained on the basis of DFT calculations. The results in this paper demonstrate that electrodeposition can be a faster and easier to operate industrial technology for the fabrication of catalyst electrodes, compared with other technologies.
研究领域:
化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2014
·Vol. 132
·期 13
·
IF 1.64
Shiquan Lai,Yan Gao,Li Yue
An attapulgite-supported Sn catalyst (Sn-palgorskite) was successfully prepared by ion-exchange co-impregnation method. The catalytic effect of Sn-attapulgite on the melt polycondensation reaction of poly(butylene succinate) (PBS) was examined by comparing with that of anhydrous SnCl 2 and a blank experiment. The structures and properties of the PBS products synthesized with the three catalytic systems were characterized by means of Fourier transform-infrared spectra (FT-IR), viscosity measurements, wide angle X-ray diffraction (WARD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Meanwhile, the acidolysis degradation behaviors of the PBS samples were also studied. It was found that the intrinsic viscosities and the number-average molecular weights of the PBS were remarkably increased under the catalysis of Sn-attapulgite, further leading to an increase in the decomposition temperature, the crystallization temperature, and the viscous flow activation energy, while a decrease in the melting temperature, the relative degree of crystallinity, and the rate of degradation. Additionally, no significant differences were observed in the crystal structures of all the samples, regardless of the reaction system with or without catalyst. The experiment results confirmed that Sn-attapulgite was an effective heterogeneous catalyst for the synthesis of PBS, and the recycled Sn-attapulgite still exhibited higher activity than anhydrous SnCl 2 under identical reaction conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41729.
研究领域:
材料科学
·
催化化学
✓ 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）