ENERGY & FUELS
·
2024
·
IF 5.2
Xin Huang,Guangchuan Tang,Lei Tang,Chuan Ma,Yunlin Shao,Jingyu Ran
Bio-based platform chemicals are of great significance to future green fine and commodity chemicals. This study reports the performances and mechanisms of solvothermal dehydration of levoglucosan (LGA), the main precursor from noncatalytic pyrolysis of cellulose with a yield up to 80 wt %, to levoglucosenone (LGO) using cesium heteropolyacid salts at the catalyst in DMSO solvent. Catalyst characterizations revealed that cesium was well doped in the cubic of heteropolyacids, and the cesium doping ratio substantially influenced the catalytic performances toward LGO. LGO yield first increased and then decreased with the increase of cesium doping ratios, which is consistent with the change trends of pore structures and Brønsted/Lewis acid site ratios of the cesium heteropolyacid salts. LGO was obtained with the maximum yield at 41.2% over Cs2H2SiW12O40 compared to 39.2% over Cs2.5H0.5PW12O40. The catalyst can be regenerated by calcination without losing its catalytic performances. In addition, density functional theory calculation was used to reveal the mechanism for LGO formation, and the rate-determining step was the first step of the dehydration reaction with the energy barrier of 166 kJ/mol.
研究领域:
化学工程
·
可再生资源与环境科学
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DOI
高影响因子
Catalysts
·
2019
·Vol. 9
·期 4
·320
·
IF 3.444
Yuehong Yu,Daoming Sun,Shuanjin Wang,Min Xiao,Luyi Sun,Yuezhong Meng
Phosphotungstic and silicotungstic acid salt catalysts (CuPW, CuSiW, FePW, FeSiW) were synthesized by substitution of protons with ferric and copper ions through a simple replacement reaction. The structure and thermal stability were characterized by IR, XRD and TG, and the salts showed a keggin structure and a thermal tolerance near 450 °C. Temperature programmed reactions indicated that the four catalysts showed similar trends in the change of methanol conversion, DME selectivity, and light olefins selectivity at 100–400 °C. Copper salt catalysts showed a 100% DME selectivity at temperatures ranging from 100–250 °C, while FeSiW and FePW catalysts had a 100% DME selectivity near 250 °C. Moreover, the heteropolyacid salt catalysts also produced a certain number of light olefins at the temperature ranging from 250–350 °C, and the CuSiW catalyst exhibited the highest ethylene and propylene selectivity of 44%. In the stability test evaluated at 200 °C, the catalysts showed different tendencies during the induction period and the same trends during the reduction period for the methanol conversion to DME, due to the differences in the strengths of the strong acid sites. Finally, the silicotungstic acid salt catalysts showed the longest lifetime of 120 h, much longer than the heteropolyacids. This approach provides an effective way to synthesize hydrocarbons through methanol, especially DME, at different temperatures using one catalyst.Keywords:methanol to hydrocarbons;heteropolyacid salts;dimethyl ether;temperature programmed reaction
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 45
·35453-35460
·
IF 3.84
Chunyan Sun,Feng Zhang,Shengfang Li,Fangqin Cheng
The ordered hexagonal mesoporous silica (SBA-15) encapsulated ammonium molybdophosphate (AMP) was successfully synthesized using low-grade natural clay from Qaidam Basin as silica and aluminum source, through a one-pot synthesis method. The final product was fully characterized, which indicated that the composite material had better AMP dispersion and immobilization in the mesoporous structure of SBA-15. The adsorption capacity of the final product for removing cesium ions in solution was also investigated. Results suggested that Qaidam natural clay is a promising low-cost precursor for the production of mesoporous silicate supports, and the final composite material is effective for the adsorption of cesium ions from solution containing other alkali metal ions.
研究领域:
材料科学
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环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
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2021
·Vol. 28
·期 12
·1-15
·
IF 3.097
Ma Guihua,Zheng Youxiong,Zhou Yuting,Gao Li,Liu Bingxin,Yu Xingchang,Zhang Lei
The ammonium molybdophosphate (AMP) with excellent ability of separation and extraction for radioisotope 137 Cs and Cs + in saline has a high solubility in water, which avoids its adsorbent role to extract Cs + from enhydrous solutions directly. In our paper, the copolymers as the carrier of AMP are prepared via RAFT (reversible addition-fragmentation chain transfer) polymerization, and the AMP is covalently located in shell or core of self-assembled copolymer micelles for efficient Cs + adsorption. The influence of the initial concentration of Cs + , the pH value and the dosage of adsorbents, and the adsorption performance of Cs + is evaluated. The initial concentration of Cs + has little effect on the adsorption effect, and the optimal pH of the solution is 7.0. The adsorption–desorption cycles indicate that the micelles have excellent stability and capability for regeneration. The adsorption process of Cs + follows the quasi-second-order kinetic model, and the adsorption equilibrium is reached within 3 h. And the equilibrium adsorption capacities are 8.49 mg/g (AMP in shell of micelle) and 9.34 mg/g (AMP in core of micelle), respectively. According to the Langmuir adsorption model, the maximum adsorption capacity of Cs + on micelles is 71.79 mg/g and 164.20 mg/g, respectively, and the adsorption process is single-layer adsorption. The principle of Cs + selective adsorption is the Cs + and NH 4 + exchange reaction in the gaps of the AMP. The results show that micelle with AMP loaded in shell is considered to be the more suitable adsorbent for separating and extracting Cs + .
研究领域:
材料科学
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环境科学
·
放射化学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2017
·Vol. 134
·期 44
·45491
·
IF 1.86
Chengle Wang,Zhijing Wang,Juan Li
The role of dual imidazolium polyoxometalates (POMs) in the flame retardancy of polypropylene/intumescent flame retardant (PP/IFR) composites was studied. The results showed that the structures of dual imidazolium POMs have a great effect on the flame retardancy of PP composites. The dual imidazolium POMs based on an ethyl group (EMIPMA) obtain the best flame retardant efficiency. With 15.5 wt % IFR and 0.5 wt % EMIPMA, the PP composites reach a limiting oxygen index of 25.7 and the UL-94 V-0 standard. However, the dual imidazolium POMs containing a butyl (BMIPMA) or hexyl (HMIPMA) group cannot achieve the UL-94 V-0 standard at the same formulation. Dual imidazolium POMs not only promote the formation of good char, but also induce the formation of intumescent char with a hierarchical and microporous structure that helps to prevent gas and heat from transferring from the flame to the resin. Therefore, the flame retardancy of PP/IFR composites is improved. However, excessive combustible components produced by BMIPMA or HMIPMA deteriorate the flame retardancy of PP/IFR composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45491.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2013
·Vol. 109
·期 1
·199-212
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IF 1.104
Li Guixian,Li Yazhen,Mu Ruina,Xu Yanduo,Dong Peng
The surface of acid-activated attapulgite (ATP) was modified by grafting 3-aminopropyltriethoxysilane (APTES) for the immobilization of heteropolyacid salt Co 4 HP 2 Mo 15 V 3 O 62 (CoHPAs). The samples were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, specific surface area measurements, thermal analysis and field emission scanning electron microscopy. The catalytic activity was tested for the oxidation of ethylbenzene in the presence of 50 % H 2 O 2 for the first time in this work. It was found that the activity of the ATP supported CoHPAs catalyst is obviously influenced by APTES grafting. The CoHPAs/ATP APTES catalyst exhibits high activity owing to the silylation of ATP, with the conversion of ethylbenzene and selectivity of acetophenone up to 72.7 and 95.4 %, respectively. The results also show that the CoHPAs/ATP APTES catalyst can be reused at least five times without significant decrease of activity.
研究领域:
催化化学
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绿色化学
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有机合成
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材料化学
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工业催化
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环境友好工艺
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DOI
高影响因子
CATALYSIS LETTERS
·
2022
·Vol. 153
·期 2
·1-11
·
IF 2.936
Jilei Liang,Mengmeng Wu,Nianqing Zhu,Xinxing Gao,Guanxing Zhu,Tingting Huang,Yunqi Liu,Chenguang Liu
With the help of hydrogen bonding and π⋯π stacking, the small molecular clusters in the impregnating solution was induced to self-assemble and form a new Ni–Mo polyoxometalate based on octamolybdate with a molecular formula of [Ni(pyz) 6 ] [Mo 8 O 26 (pyz) 2 ]⋅10H 2 O (pyz = pyrazole). The polyoxometalate was structurally characterized detailed by various technologies, and its sulfide was also characterized to make a preliminary study to explore the use of it as a potential NiMoS active phase precursor. Much more NiMoS active phase and higher catalytic activity of the Ni–Mo sulfided catalyst was found, and the structure-directing effects can account for the phenomenon. The results show the Ni–Mo polyoxometalate [Ni(pyz) 6 ] [Mo 8 O 26 (pyz) 2 ]⋅10H 2 O can make a superior precursor to prepare the hydrodesulfurization catalyst, and it provides a new preparation methodology to the rational design and controllable preparation of superior hydrodesulfurization catalysts. Graphical Abstract
研究领域:
无机化学
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材料科学
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催化
·
化工
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DOI
高影响因子
Advanced Science
·
2019
·Vol. 6
·期 17
·1900381
·
IF 15.804
Jian Lin,Lin Zhu,Zenghui Yue,Chuang Yang,Wei Liu,Thomas E. Albrecht-Schmitt,Jian-Qiang Wang,Shuao Wang
Various types of polyoxometalates (POMs) have been synthesized since the 19th century, but their assortment has been mostly limited to Groups 5 and 6 metals. Herein, a new family of POMs composed of a carbon group element as the addenda atoms with two distinct phases, LnPbOClO 4 -1 (Ln = Sm to Ho, Y) and LnPbOClO 4 -2 (Ln = Er and Tm) is reported. Both structures are built from [Ln 6 O 8 ] rare-earth metal hexamers being incorporated in [Pb 18 O 32 ]/[Pb 12 O 24 ] polyplumbites, and unbound perchlorates as charge-balancing anions. Impressively, YPbOClO 4 -1 and ErPbOClO 4 -2 exhibit exceptional uptake capacities (434.7 and 427.7 mg g −1 ) toward ReO 4 − , a chemical surrogate for the key radioactive fission product in the nuclear fuel cycle 99 TcO 4 − , which are the highest values among all inorganic anion-exchange materials reported until now. The sorption mechanism is clearly elucidated and visualized by single-crystal-to-single-crystal structural transformation from ErPbOClO 4 -2 to a perrhenate-containing complex ErPbOReO 4 , revealing a unique ReO 4 − uptake selectivity driven by specific interaction within Pb···O-ReO 3 − bonds.
研究领域:
无机化学
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放射化学
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环境化学
·
材料科学
·
核燃料循环
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2023
·
IF 5.2
Yan Gao,Shumin Zhao,Miao Yan,Yongxia Li,Jianshe Zhao
In this work, the encapsulating peroxo-polyoxometalate in the mesoporous of metal-organic framework (MIL-101(Fe)) to synthesize composite according to the principle of host-guest matching. The structure of the host-guest composite was analyzed by a variety of methods, and the catalytic activity for desulfurization was investigated under mild conditions. The composites combine the advantages of peroxo-polyoxometalate (high efficiency) and MIL-101(Fe) (good recyclability and high porosity), showing synergistic effect between host and guest. The sulfur-containing organic compounds in simulated liquid fuel can be almost completely removed under the catalysis of PW 4 @MIL-101(Fe). The catalyst PW 4 @MIL-101(Fe) can be reused for 10 times without prominent decrease in desulfurization activity, indicating that it has good reusability due to the confinement effect between the window size of MIL-101(Fe) and molecular size of PW 4 . In addition, several control experiments and electron spin resonance experiment were researched to explore the possible mechanism, and the results show that the active component in the catalyst can promote the decomposition of H 2 O 2 into ·OH and thus accelerate the desulfurization reaction. This work discloses a facile and environmentally friendly method to prepare the "host-guest matching" catalyst with high activity and stable reusability, which provides ways for further developments in heterogeneous catalyst based on POM and MOF.
研究领域:
化学工程
·
催化材料科学
✓ 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）