Clean Energy
·
2025
·
IF 3.7
Jiang Zhenhua,Xia Wei,Zhang Yanli,Wang Xinrui,Dong Mingyuan,Chen Kun,Liu Dong,Lu Baowang
This study aims to compare the catalytic performance of ZSM-5 and SAPO-34 zeolite catalysts in the conversion of ethanol. Through experiments conducted at different temperatures (773 K and 673 K), it was found that SAPO-34 initially exhibits superior propylene selectivity compared to ZSM-5. However, the propylene yield on SAPO-34 gradually decreases, while the ethylene yield increases with time on stream. density functional theory calculations were employed for the investigation of reaction mechanism. The results indicate that the SAPO-34 catalyst surface favors propylene desorption, which beneficial for its initial high propylene selectivity. Nevertheless, the smaller pore structure of SAPO-34 limits the effective diffusion of products, leading to product accumulation within the pores and potentially causing catalyst coking and deactivation. By combining the experimental results with theoretical calculation, this study not only explored the selectivity difference between SAPO-34 and H-ZSM-5 in ethanol conversion reaction, but also revealed the influence of different molecular sieve catalyst structures on product distribution and catalyst stability.
研究领域:
催化化学
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材料科学
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计算化学
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产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2018
·Vol. 15
·期 6
·1490-1501
·
IF 1.165
Xiangli Kong,Minghui Qiu,Anran Wang,Lu Yang,Rongfei Zhou,Yiqun Fan,Deshuang Kong,Changjun Gu
The adhesion and cohesion between the coating layers and the ceramic honeycombs are usually one of the key issues in the preparation of high-performance zeolite-based/Monolith catalysts. In this work, we investigate the deposition of high-efficiency Cu-SAPO-34 catalyst on a cordierite monolith with special focus on the impact of alumina binders on the structure, mechanical adhesion and cohesion, and catalytic performance of the monolithic catalyst. Two kinds of alumina nanoparticles, α-alumina and γ-alumina, have no significant impacts on the Cu-SAPO-34 crystal structure, micropore morphology and catalytic activity. But washcoating experiments showed that the mass loss rate of the coating was less and the loading of the catalyst was higher when α-alumina was used as the binder. The reason of improving the adhesion and cohesion strength is the suitable thermal shrinkage, the uniform distribution and densification structure of α-alumina. Furthermore, optimization of the coating formulation with α-alumina as the binder has been performed. Finally, the catalyst prepared under the optimal conditions was tested by SCR and a maximum conversion rate of 97.4% was obtained. It was concluded that the use of the washcoating method with α-alumina does not affect catalytic performance while it increases bonding strength between substrate and catalysts.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
ACS Catalysis
·
2021
·
IF 13.084
Yuebing Xu,Wenda Yu,Hao Zhang,Jian Xin,Xiaohui He,Bing Liu,Feng Jiang,Xiaohao Liu
Various Co-based SAPO-34 catalysts were prepared using different methods, including ion exchange (IE), incipient-wetness impregnation (IWI), and solid-phase grinding (SPG), to correlate the chemical states of Co species with the C–H and C–C bond scissions in ethane dehydrogenation. The IE-prepared Co/SAPO-34 led to stable, unreducible, and isolated exchanged Co sites anchored on the zeolite framework with a structure of −AlF–O–Co–O– and showed the highest selectivity to ethylene of close to 98% at 600 °C, which suggests that these Co sites favors suppressing the C–C bond scission in ethane. In comparison, the IWI- and SPG-prepared Co/SAPO-34 catalysts, especially for those with a high Co loading, inevitably give Co oxide clusters that are easily reduced into metallic Co. Together with catalytic results, characterizations, and DFT calculations, it is confirmed that the reduced Co clusters, especially for those outside SAPO-34 channels without the confinement effect, favor both C–H and C–C bond scission, boosting the conversion of ethane into CH4 or/and coke; however, the ionic-state −Co–O– species can smoothly terminate the ethane dehydrogenation for the ethylene product due to relatively high energy barriers for both C–H and C–C bond scission, avoiding a deep dehydrogenation and C–C cracking. As expected, the unreducible −Co–O– sites are very stable in the title reaction without deanchoring from the zeolite framework in a 100 h cyclic test. This study not only demonstrates the stable −Mδ+–Oδ− structure favorable for suppressing C–C bond scission but also highlights a catalyst-constructing strategy for Co-based and similar metal-based catalysts for dehydrogenation of other light alkanes.
研究领域:
催化化学
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材料科学
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计算化学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Xiaoli Ding,Yongfu Tang,Hongyong Zhao,Qingping Xin,Yuzhong Zhang
Hollow SAPO-34 with an average particle size of ca .370 nm was synthesized by selective etching its precursor under the controlled alkaline condition. Subsequently, freestanding mixed matrix membranes were synthesized by UV-induced in-situ polymerization of the mixture of hollow SAPO-34, the fluorinated monomer , and the trifunctional cross-linker. The structure and the physical characteristic of hollow SAPO-34 and membranes were characterized by scan electron microscope, wide-angle X-ray diffraction, etc. The effect of the hollow SAPO-34 loading amount on the gas permeation-separation performance of mixed matrix membranes was investigated. The results showed that hollowing out SAPO-34 improved the N 2 /CH 4 sorption selectivity and converted the crystals from preferential adsorption of N 2 to preferential adsorption of CH 4 , the incorporation of hollow SAPO-34 into membranes increased the N 2 /CH 4 solubility selectivity and the permeability. The optimal membrane exhibited a 39-fold increase in N 2 permeability from 6.9 × 10 −13 to 2.7 × 10 −11 cm 3 (STP)cm·cm −2 ·s −1 ·Pa −1 at 0.2 MPa and 35 °C without the loss of N 2 /CH 4 permselectivity, which exceeded the 2008 Robeson upper bound.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Senliang Xi,Xiaojun Wang,Kudzaishe Caren Tome,Tonghuan Zhang,Zongying Han,Meng Gao,Shixue Zhou,Hao Yu
The hydrogen storage performances of MgH 2 improved by the addition of Ni and SAPO-34 were studied in detail. The mixture of MgH 2 with Ni and SAPO-34 was a physical reaction as shown by the X-ray diffraction (XRD) results. The SAPO-34 and Ni were uniformly distributed on the surface of MgH 2 . The thermodynamic and kinetic properties of 90MgH 2 /5Ni/5SAPO-34 were investigated by differential scanning calorimetry (DSC) and pressure-composition-isothermal (PCI) methods. The results showed that the dehydrogenation activation energy of 90MgH 2 /5Ni/5SAPO-34 decreased by 64.3 kJ/mol compared with that of MgH 2 . In addition, the relationship between the value of dehydrogenation heat and hydrogen content was also investigated by in-situ calorimetry. The enthalpy value of each sample in the dehydrogenation processes were calculated by in-situ calorimetry measurement. The dehydrogenation enthalpies of as-milled MgH 2 and 90MgH 2 /5Ni/5SAPO-34 were 63.2 kJ/mol H 2 and 53.6 kJ/mol H 2 , respectively. Thus, the co-doping of Ni and SAPO-34 contributed significantly to decrease the thermodynamic stability and improve the hydrogen sorption kinetic properties of MgH 2 .
研究领域:
材料科学
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氢储能技术
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物理化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 51
·32146-32154
·
IF 3.108
Chengkai Pang,Yuqun Zhuo,Qiyu Weng
A series of Mn-exchanged SAPO-34 catalysts were synthesized and developed as catalysts for the low temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. 4Mn/SAPO-34 showed the highest SCR activity in the temperature range of 120–210 °C. The microstructure of zeolite supports, acidity, manganese species and reaction mechanism were investigated in detail by BET, NH3-TPD, UV-Vis, H2-TPR, XPS and in situ DRIFTS. Mn3+ and Mn4+ related species were proved to be the active sites for the SCR reaction. The Eley–Rideal mechanism was proved to be effective on 4Mn/SAPO-34 for the low temperature SCR reaction in which coordinated NH4+ species react with gas-phase NO to form an activated transition state and subsequently decomposed to N2 and H2O.
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2020
·
IF 6.146
Qianqian Guo,Fan Yang,Xiaohui Liu,Mengqing Sun,Yong Guo,Yanqin Wang
Silicoaluminophosphate-34 (SAPO-34) molecular sieves have important applications in the petrochemical industry as a result of their shape selectivity and suitable acidity. In this work, nanoaggregate SAPO-34 with a large external surface area was obtained by dissolving pseudoboehmite and tetraethylorthosilicate in an aqueous solution of tetraethylammonium hydroxide and subsequently adding phosphoric acid . After hydrolysis in an alkaline solution, the aluminum and silicon precursors exist as Al(OH) 4 − and SiO 2 (OH) − , respectively; this is beneficial for rapid nucleation and the formation of nanoaggregates in the following crystallization process. Additionally, to study the effect of the external surface area and pore size on the catalytic performance of different SAPO-34 structures, the alcoholysis of furfuryl alcohol to ethyl levulinate (EL) was chosen as a model reaction. In a comparison with the traditional cube-like SAPO-34, nanoaggregate SAPO-34 generated a higher yield of 74.1% of EL, whereas that with cube-like SAPO-34 was only 19.9%. Moreover, the stability was remarkably enhanced for nanoaggregate SAPO-34. The greater external surface area and larger number of external surface acid sites are helpful in improving the catalytic performance and avoiding coke deposition.
研究领域:
石油化工
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材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2019
·Vol. 128
·期 2
·1065-1077
·
IF 1.428
Yu Qifan,Liu Xuesong,Chen Hongfeng,Liu Shuang,Jiang Peng
The regeneration mechanism of sulfated Cu/SAPO-34 catalysts in reducing atmospheres (5% H 2 /Ar and NH 3 /Ar at 600 °C) was investigated by using a series of characterization methods. Hydrogen regeneration improved the catalysts’ NH 3 -SCR activity from 150 to 550 °C remarkably, while ammonia regeneration exhibited relatively less obvious promotion effect. The TPR of hydrogen and EPR spectra data show that the regeneration process affects the amount and the coordination of the active isolated Cu 2+ species significantly. The desulfation increases the amount of isolated copper ions and improves the catalytic activity of SCR.
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 53
·47864-47872
·
IF 3.289
Chan Wang,Miao Yang,Wenna Zhang,Xiong Su,Shutao Xu,Peng Tian,Zhongmin Liu
With the aid of self-designed organophosphorous surfactant [2-(diethoxylphosphono)propyl]hexadecyldimethylammonium bromide (DPHAB), SAPO-34s with various special morphologies have been hydrothermally synthesized by using tetraethylammonium hydroxide (TEAOH), diethylamine (DEA) and triethylamine (TEA) as templates, respectively. The synthesized SAPO-34s were well characterized by XRD, XRF, SEM, N2 adsorption–desorption, solid state NMR and NH3-TPD measurements. The status of DPHAB was also investigated by using FT-IR, 13C NMR, TG–DTA and 31P NMR measurements as well as density functional theory calculations. It is found that the addition of DPHAB changes the crystal morphology dramatically and the aggregation degree of the crystals increases with the rising DPHAB/H3PO4 ratio. Moreover, microporous templates play an important role in the synthesis of mesoporous SAPO-34. TEAOH, which has the strongest interaction energy with the CHA framework among the investigated templates, shows the best cooperating ability with an organophosphorous surfactant to direct the formation of nanosized and mesoporous SAPO-34. The prepared SAPO-34s showed improved catalytic properties in the methanol-to-olefins (MTO) reaction.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
2024
·
IF 2.5
Liang Ni,Wang Haiyan,Wang Yujia,Kang Lei,Bai Yingzhi,Sun Na
A strategy was devised for the synthesis of SAPO-34, which involved a concentrated gel system-assisted two-step crystallization method. This strategy effectively controlled the size and morphology of SAPO-34. The successful synthesis of SAPO-34 crystals with micron-scale cubic morphology and nano-scale sheets were achieved using triethylamine as a low-cost template. The paper thoroughly examined the growth evolution that occurs during the crystallization process, and it delved into the factors such as gel concentration and crystallization conditions in the synthesis. Furthermore, potential theories regarding nucleation and growth mechanisms were suggested. A systematic study was conducted to examine how the morphology and acidity of SAPO-34 zeolites impact their catalytic performance. The results confirmed that the SAPO-34 with low silicon content and lamellar structure was successfully synthesized through a two-step crystallization within a gel system of H 2 O/Al 2 O 3 = 30, with a thickness of approximately 50–300 nm. SAPO-34 nanosheets demonstrated a substantial enhancement in catalytic performance, with a catalytic life of 370 min and an 84.1% selectivity towards light olefins.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Gang Li,Shuanshi Fan,Zijian Zhang,Yanhong Wang,Xuemei Lang,Jing Li
SAPO-34 zeolite membranes were activated by ultraviolet (UV) radiation at low temperatures to reduce grain boundary defects. The successful detemplation of SAPO-34 zeolite powders using UV radiation was confirmed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and nitrogen adsorption-desorption. The irradiance exerted a significant impact on the quality of UV-detemplated SAPO-34 membranes. Under optimal UV detemplation conditions, SAPO-34 membranes showed a moderate H 2 permeance of ∼10 −7 mol Pa −1 m −2 s −1 , with a H 2 /i-C 4 H 10 permselectivity over 75 under room temperature. The membranes showed an exceptionally low CO 2 permeance in comparison with N 2 and CH 4 despite the smaller molecular size of CO 2 , resulting in an unprecedentedly high H 2 /CO 2 permselectivity over 50, which was ascribed mainly to the intense interaction between the CO 2 molecules and confined organic structure directing agent (OSDA) residue in membrane channels. The temperature dependence of singe-gas permeance through SAPO-34 zeolite membranes showed that gases, including He, H 2 , CO 2 , CH 4 , C 2 H 6 , C 3 H 8 , and i-C 4 H 10 , markedly increased as the temperature increased, indicating an activated diffusion mechanism. The activation energies for H 2 permeation through the SAPO-34 membranes were 17–23 kJ mol −1 , which were reasonable based on the correlation between the activation energy for H 2 permeation and the average pore size for reported membranes by assuming minimal grain boundary defects in the UV-detemplated SAPO-34 membranes.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2014
·Vol. 90
·期 3
·415-422
·
IF 2.494
Yanping Chen,Yiming Xu,Dang-guo Cheng,Yingcai Chen,Fengqiu Chen,Xiaoyong Lu,Yiping Huang,Songbo Ni
BACKGROUND The synthesis of C 2 –C 4 hydrocarbons from coal or biomass-derived syngas has received increasing attention because of the resource constraints of petroleum. The present study explores direct production of hydrocarbons from syngas over bifunctional catalyst containing methanol synthesis catalyst CuO–ZnO–Al 2 O 3 (CZA) and SAPO-34 zeolite. RESULTS The synthesis of C 2 –C 4 hydrocarbons from syngas was investigated over CZA/SAPO-34 bifunctional catalyst at temperatures ranging from 240 to 440°C. The results indicate that higher temperatures aggregate Cu metal and lead to the deactivation of CZA. The predominant products are dimethyl ether (DME) and methanol at temperatures from 280 to 360°C and a small amount of hydrocarbons are found due to the deactivation of SAPO-34 caused by a type of coke named ‘inert coke’. While 96.5% selectivity of C 2 –C 4 hydrocarbons in products of all hydrocarbons can be obtained at 400°C with less coke named ‘active coke’. CONCLUSION Reaction temperatures have significant effect on the selectivity of C 2 –C 4 hydrocarbons and coke species of SAPO-34. The ‘active coke’ of poly methyl-substituted benzene/naphthalene (MB/MN) acts both as an intermediate and as coke deposition. The ‘inert coke’ of poly methyl-substituted adamantine (MA) and other groups-substituted benzene/naphthalene acts only as coke depositions. Comprehensive consideration of the characteristics of this bifunctional catalyst, shows that a moderate temperature for C 2 –C 4 hydrocarbons synthesis from syngas might be approximately 400°C. © 2014 Society of Chemical Industry
研究领域:
化学工程
·
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）