INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Jingying Xu,Xuan He,Jiale Zhu,Xianqing Shao,Xuedong Zhu
The investigation of the synthesis of pure-phase ZSM-22 zeolites and their catalytic performance in the n-hexane cracking reaction is of critical significance for industrial production. To enhance the crystallinity of ZSM-22, ethylene glycol was integrated into the synthesis gel, effectively suppressing the formation of quartz and ZSM-5 impurities. Due to the structure-directing effect of ethylene glycol, the ZSM-22 prepared demonstrates much more mesopores compared to the counterparts without ethylene glycol addition. Furthermore, the acid strength and density of the zeolite increased significantly. These pure-phase ZSM-22 samples exhibited enhanced performance in terms of both conversion efficiency and ethylene selectivity during n-hexane cracking, which is associated with the increased abundance of acid sites and a higher ratio of strong to weak acids. These findings highlight the beneficial effects of ethylene glycol modification on the regulation of crystal growth and the enhancement of catalytic performance in ZSM-22 catalysts.
研究领域:
化学工程
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催化
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2021
·
IF 5.706
Xiaochao Xian,Mengjun He,Yakai Gao,Yi Bi,Yirong Chu,Jun Chen,Lichun Dong,Jin Wang,Shuo Zhao
Reducing the acid density and strength of HZSM-5 zeolite are typical strategies to inhibit coke deposition during catalytic cracking reactions. Herein, direct titration of HZSM-5/H 2 O suspension using dilute NaOH aqueous solution at room temperature was introduced to neutralize excessive Brønsted acid sites of HZSM-5 zeolite (Si/Al = 25). SEM, XRD, N 2 adsorption and n -propylamine temperature-programmed decomposition confirmed that simultaneous acid strength weakening and acid density reducing were achieved without obvious influence on crystalline or textural property. The evolution of the surface charge during the titration process tracked by Zeta-potential measurement reveals that the mechanism of such neutralization is: liquid phase neutralization between H + and OH − & solid phase ion exchange between Na + and H + . Supercritical catalytic cracking of n -dodecane over a series of partial neutralized HZSM-5 catalysts showed that moderate neutralization can enhance the conversion of n -dodecane by alleviating both the coke amount and harmfulness per unit mass of coke.
研究领域:
化学工程
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
Jove-Journal of Visualized Experiments
·
2019
·
IF 1.108
Weixiang Guan,Chuang Li,Xiao Chen,Xiao-Ying Lu,Chi-Wing Tsang,Haoquan Hu,Hongxu Qi,Changhai Liang
We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid nanosheets, a series of Pt/xHMNO6/CNTs with different solid acid compositions (x = 5, 20 wt%; M = Nb, Ta; N = Mo, W) have been prepared by carbon nanotube pretreatment, protonic exchange, solid acid exfoliation, aggregation and finally Pt particles impregnation. The Pt/xHMNO6/CNTs are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and NH3-temperature programmed desorption. The study revealed that HNbWO6 nanosheets were attached on CNTs, with some edges of the nanosheets being bent in shape. The acid strength of the supported Pt catalysts increases in the following order: Pt/CNTs < Pt/5HNbWO6/CNTs < Pt/20HNbMoO6/CNTs < Pt/20HNbWO6/CNTs < Pt/20HTaWO6/CNTs. In addition, the catalytic hydroconversion of lignin-derived model compound: diphenyl ether using the synthesized Pt/20HNbWO6 catalyst has been investigated.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Yumeng Xia,Zehua Li,Ying Li,Kai Cai,Yunduo Liu,Jing Lv,Shouying Huang,Xinbin Ma
Dimethyl ether (DME) carbonylation is an important reaction for methyl acetate (MA) and ethanol production from syngas. Mordenite (MOR) has been used as an industrial catalyst due to the competitive catalytic properties, especially with extremely high selectivity of MA (>99%). Given the Brønsted acid sites (BAS) in 8-MR are proved the active centers, the properties of BAS are crucial factors that influence the reaction. Until now, most of the researches focus on increasing the number of BAS rather than tuning the acid strength. Here we modified H-MOR by Ga introduction using incipient wetness impregnation. Catalyst evaluation results suggest that Ga species can enhance DME conversion with a maintained MA selectivity. Combining with characterizations and DFT calculation, the textural and acidic properties along with the existing form of Ga species are determined. Further in-situ IR, theoretical and kinetics investigations demonstrated that the enhanced acid strength accelerates the reaction on Ga-modified MOR catalysts. This work inspires us that improving the acid strength is an efficient strategy for Brønsted acid-catalyzed reaction, such as DME carbonylation .
研究领域:
催化化学
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理论计算化学
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2019
·Vol. 48
·期 36
·13711-13718
·
IF 4.052
Wei Zhong,Li Wu,Weidong Jiang,Yulong Li,Natarajan Mookan,Xiaoming Liu
Three benzenedithiolate-bridged diiron hexacarbonyl complexes (2, 3 and 4) with different functional groups were designed and synthesized. In addition, a well-defined benzenedithiolate-bridged complex without any functional groups, 5, was employed for comparison. Electrochemical investigations using five different acids showed that the first reduction potential of the complexes shifted positively in acidic media. This potential shift is attributed to a PCET (Proton-Coupled Electron Transfer) reaction and depends on the acid strength. When an acid is too weak (pKa ≥ 24 in this case), no potential shift is observed. Moreover, increasing the acid strength does not lead always to a linear trend in the potential shift for all of the complexes due to kinetic resistance during proton transfer for some of the complexes. The presence of a pendant basic group (2) can ease such kinetic resistance, and the linear trend holds valid up to pKa 1.8, whereas for the rest of the complexes (3–5), which do not bear an internal basic group, the correlation between the potential shift and the acid strength levels off after a certain pKa value (12). Alternatively, when the acid is strong enough to provide sufficient proton, further increases in the acid strength do not improve the potential shift and the kinetic resistance for a proton to cross the solvated layer becomes dominant.
研究领域:
无机化学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of CO2 Utilization
·
2017
·
IF 4.292
Chen Zhang,Haiyan Yang,Peng Gao,He Zhu,Liangshu Zhong,Hui Wang,Wei Wei,Yuhan Sun
A series of Cu/ZnO/Al 2 O 3 catalysts with the total weight percentage of Cu and ZnO from 9.94 wt.% to 44.5 wt.% have been prepared by ammonia deposition −precipitation method and tested for methanol synthesis from CO 2 hydrogenation. A Cu/Zn/Al layered double hydroxides (LDHs) precursor can be formed in situ on the surface of microspherical Al 2 O 3 which acts as both support and sole source of Al 3+ cations. With increase of total Cu and ZnO loading, the dispersion of copper and reducibility of CuO decline continuously, while the exposed copper surface area increases gradually. In addition, the formation of LDHs results in a stronger both basicity and acid strength on the catalyst surface. It is found that the CO 2 conversion increases linearly with increase of the Cu and ZnO loading. The methanol selectivity for the catalyst with low total metal loading (9.94 wt.%) is much lower than those for other catalysts, though it increases with increasing loading, which can be mainly assigned to the much smaller Cu particle size (<5 nm) and the higher ratio of isolated CuO phase. Moreover, the Cu/ZnO/Al 2 O 3 catalyst with relatively high total metal loading (44.50 wt.%) still exhibits a considerable stable catalytic performance due to the formation of LDH structure.
研究领域:
催化
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化学工程
·
材料科学
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环境化学
✓ 已验证
产品关联
DOI
高影响因子
Green Energy & Environment
·
2018
·
IF 0
Wei Hui,Yan Zhou,Yan Dong,Zhi-Jun Cao,Fei-Qiang He,Min-Zhong Cai,Duan-Jian Tao
Novel superacid SO 4 H-functionalized ionic liquids (SFILs) were designed and prepared in this work. The catalytic activities of SFILs were evaluated in xylan hydrolysis and xylose dehydration to produce furfural. Combined with the results of acid strength of SFILs characterized by solid-state 31 P MAS NMR, it was found that the catalytic performance of SFILs was positively correlated to their acid strength. The superacid SFIL [Ch-SO 4 H][CF 3 SO 3 ] displayed the best catalytic performance with more than 80% yield of furfural, and it was also obviously superior to usual SO 3 H-functionalized acidic ILs, mineral liquid acids, and acidic resin Amberlyst-15 catalysts in catalytic activity under optimized conditions. In addition, the superacid SFIL [Ch-SO 4 H][CF 3 SO 3 ] could be easily separated from reaction system and reused at least five times without obvious decrease.
研究领域:
化学工程
·
催化
·
绿色化学
·
可再生能源
✓ 已验证
产品关联
DOI
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Tianhao Zhang,Yuhang Bian,Luming Wang,Hui Zhao,Gang Wang,Chunshan Li
Herein, a novel continuous fixed-bed process for methacrolein (MAL) production via aldol condensation of formaldehyde with propionaldehyde over a sulfonic acid resin was developed, which exhibited high efficiency and remarkable catalytic stability. The influence of Brønsted acid strength and solvent permittivity on aldol reaction was revealed, and the optimal sulfonic acid resin (NKC-9) with suitable acid strength (H0 = 0.46) was identified. Meanwhile, the occupancy of water molecules on acid sites, which would lead to side reactions and catalyst deactivation, could be effectively inhibited through the construction of a liquid–solid catalytic system in non-polar media. The propionaldehyde conversion and MAL yield could reach up to 97.3 and 90.1% after optimization using the response surface method, respectively. Kinetic studies revealed that the surface reaction was the rate-limiting step with an activation energy of 57.1 kJ/mol. No deactivation behavior was observed for this kind of catalyst after 300 h on stream.
研究领域:
化学工程
·
催化
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2025
·
IF 4.8
Ruxing Zhao,Qingrun Meng,Guanchao Wang,Lin Xu,Weifeng Chu,Junjie Li
Intermolecular dehydration of 2-propanol (IPA) to di-isopropyl ether (DIPE) serves as an important process to produce the valuable chemical, however, developing advanced solid acid catalysts with high DIPE selectivity faces the great challenge of inhibiting the intramolecular dehydration reaction. In this context, we developed a highly selective intermolecular dehydration MFI nanosheet catalyst by synergistically modifying its diffusion and acid properties. We found that the DIPE selectivity over nanosheet ZSM-5 catalysts were obviously higher than that over the conventional ZSM-5 catalyst, benefited from the enhanced diffusion property over nanosheet catalysts that inhibited the further conversion of DIPE. However, the DIPE selectivity were still lower than 70 % over those catalysts attributed to their high acid strength that facilitated the intramolecular dehydration reaction. Thus, various heteroatoms (Fe, Ga, and B) substituted MFI zeolite nanosheet catalysts were prepared and employed in the dehydration reaction, Fe-MFI with a moderate acid strength exhibited the highest DIPE selectivity among those catalysts. Besides, the effects of acid amounts (Si/Fe ratio) and diffusion properties (thickness of b-axis) on the intermolecular dehydration selectivity and activities over nanosheet Fe-MFI catalysts were systematically investigated. An optimal Fe-MFI nanosheet catalyst with the b-axis thickness of ∼20 nm and Si/Fe ratio of ∼40 presented the stable high DIPE selectivity of ∼91 % in 360 h of time on stream, meanwhile the IPA conversions kept almost unchanged.
研究领域:
催化
·
材料科学
·
化学反应工程
·
纳米技术
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Fanglin Huo,Qing Liu,Zhendong Liu,Yangcheng Lu
Metal-incorporated zeolites as heterogeneous Lewis acid were applied in the ring-opening acidolysis of ethylene oxide with acrylic acid to prepare 2-hydroxyethyl acrylate (HEA). The catalysis characteristics, including Lewis acid strength and internal mass transfer resistance, were systematically investigated to facilitate the rational design of zeolite catalysts. Through modifying the Lewis acid strength of zeolites via different metals (Sn, Zr and Ti) incorporation and the internal mass transfer resistance of zeolites from the particle size, pore diameter or pore structure, it was found that the increased Lewis acidity can accelerate both the main and side reactions, resulting in the high activity but low selectivity of zeolite catalysts; the enhanced internal diffusion was the key to limiting subsequent cascade alcoholysis side reactions as well as the decline of catalytic performance. Based on these findings, Zr-containing zeolites featured with moderate Lewis acidity and uniform intracrystalline mesoporosity were designed and prepared, presenting excellent catalysis and recycling performance. These results demonstrated the great potential of the developed zeolite catalysts for the green synthesis of HEA as well as the similar ring-opening acidolysis of epoxides.
研究领域:
催化
·
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
BIOMASS & BIOENERGY
·
2022
·
IF 5.774
Wenlu Zhang,Chunrong Wang,Beining Luo,Peihang He,Lei Zhang,Guoqiang Wu
With the aim of developing efficient heterogeneous catalysts for production of clean biodiesel through the transesterification process, a novel Mo catalyst supported on the outer surface of ZSM-22 ( x Mo/ZSM-22) was developed and synthesized successfully with the wet impregnation method. The characterization results showed that the Mo(VI) oxide species were highly dispersed on the surface of catalysts under the Mo-loading not higher than 5%, and the aggregation of the MoO 3 nanoparticles were detected above the Mo-loading of 5%. Meanwhile, the maximum acid intensity was also exhibited in the 5Mo/ZSM-22 catalyst. As a result, the catalytic performance of Mo/ZSM-22 catalysts in the transesterification of waste cooking soybean oil (WCSO) was significantly improved compared with the untreated ZSM-22 catalyst. Especially, the 5Mo/ZSM-22 showed the good activity (X WCSO of 59.29%, S Biodiesel of 99.86%), which was mainly due to the well dispersed Mo species and the larger acidity. Additionally, the 5Mo/ZSM-22 catalyst exhibits good stability and the high biodiesel selectivity , and the fuel properties of the as-synthesized biodiesel meet ASTM D6751 standards. This work provides a useful synthesis strategy of transesterification catalysts for the preparation of biodiesel.
研究领域:
化学工程
·
催化
·
可再生能源
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ChemSusChem
·
2019
·Vol. 12
·期 22
·4986-4995
·
IF 7.804
Danping Yuan,Lei Li,Feng Li,Yanxia Wang,Feng Wang,Ning Zhao,Fukui Xiao
Graphical Hard graft : A series of polymeric solid acid catalysts (PDSF- x ) is prepared by grafting strong electron-withdrawing groups (−SO 2 CF 3 ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor. The effect of acid strength on sorbitol dehydration is investigated. A series of polymeric solid acid catalysts (PDSF- x ) is prepared by grafting strong electron-withdrawing groups (−SO 2 CF 3 ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor synthesized hydrothermally. The effect of acid strength on sorbitol dehydration is investigated. The textural properties, acidity, and hydrophobicity are characterized by using Brunauer–Emmett–Teller analysis, elemental analysis, and contact angle tests. The results of FTIR spectroscopy and X-ray photoelectron spectroscopy show that both −SO 3 H and −SO 2 CF 3 are grafted onto the polymer network. We used solid-state 31 P NMR spectroscopy to show that the acid strength of PDSF- x is enhanced significantly compared with that of PDS, especially for PDSF-0.05. As a result, PDSF-0.05 exhibits the highest isosorbide yield up to 80 %, a good turnover frequency of 231.5 h −1 (compared to other catalysts), and excellent cyclic stability, which is attributed to its large specific surface area, appropriate acid strength, hydrophobicity, and stable framework structure. In addition, a plausible reaction pathway and kinetic analysis are proposed.
研究领域:
化学
·
催化
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）