Greenhouse Gases-Science and Technology
·
2022
·Vol. 12
·期 2
·305-320
·
IF 2.518
Zichen Liu,Shuman Xu,Jing Hao,Lina Song,Mingben Chong,Dang-Guo Cheng,Fengqiu Chen
The conversion of CO 2 into high-value chemicals has drawn a great deal of consideration, of which the most ideal product is lower olefins. However, the modified Fischer–Tropsch (F-T) synthesis with CO as an intermediate shows poor selectivity for lower olefins. Here, a list of bifunctional catalysts consisting of SAPO-34 zeolites with adjustable silicon contents and In 2 O 3 /ZrO 2 were synthesized. In the reaction process, CO 2 is first hydrogenated to methanol over an In 2 O 3 /ZrO 2 catalyst, and then the generated methanol rapidly diffuses to the adjacent zeolite catalyst to react to lower olefins. The selectivity of lower olefins (88.3%) and conversion rate of CO 2 (23.3%) was achieved over In 2 O 3 /ZrO 2 and SAPO-34-0.05 at 633 K, a gas hourly space velocity (GHSV) of 4500 ml·gcat –1 ·h –1 , and H 2 /CO 2 /Ar = 3:1:1. The catalytic performance remained stable after 50 h of reaction. Characterization analysis showed that Si content affected the content of Brønsted acid sites (BAS) and morphology of SAPO-34, resulting in different distribution of reaction intermediates. Tetramethyl-benzenes, as important intermediate species, had a slower conversion rate on the SAPO-34 with low Si content and nanosheet morphology, which led to high lower olefins selectivity. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.
研究领域:
催化
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化学工程
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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
FUEL
·
2024
·
IF 6.7
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao
The application of non-noble metal supported catalysts in the hydroisomerization of long-chain n-alkanes is a novel field, and there is currently not any research available on the deactivation process of these catalysts. We investigated into the deactivation mechanism of NiWS/SAPO-11 catalyst in the hydroisomerization of n-hexadecane in this work for the first time. Specifically, coke deposition behavior and active phase migration were investigated. The reduction of catalytic efficiency of the catalyst was partially aided by the decrease in specific surface area, pore volume, and acid density. From the perspective of the active phase, the clusters of NiWS active phase migrated as the reaction time increased, mostly resulting in an increase in both the stacking number and the length of active phase slabs. The migration of active phase increased the distance between active phase clusters and metal sites, and decreased the utilization ratio of active metal atoms. From the perspective of coke deposition, the coke formed on the catalyst includes soft coke and hard coke. The formation and evolution of coke on the catalyst were investigated. The soft coke (aliphatic compounds) progressively transformed into hard coke (polycyclic aromatic hydrocarbons and graphite-like), and the coke gradually migrated from the external surface of the catalyst to the pore channels as the reaction time increased. It is expected to provide theoretical basis and reference value for the deactivation research and design of non-noble metal supported hydroisomerization catalyst.
研究领域:
催化
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化学工程
·
石油化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Qibo Liu,Jingce Bi,Zhouxiao Zhai,Wen Tian,Ningning Liu,Xia Zhang,Zhuopeng Wang,Huanying Zhou,Yide Han
Rate-limiting mass transfer is a critical issue for using iron-based catalysts supported by zeolites to activate peroxydisulfate (PDS) in the field of advanced oxidation processes (AOPs). In this study, hierarchically porous Fe-SAPO-34-DGC was synthesized via combing in-situ encapsulation method with dry gel conversion (DGC) technology. Tetracycline (TC) was applied as a model pollutant, about 91.5% TC in Fe-SAPO-34-DGC/PDS system can be degraded within 90 min, while it can be achieved for about 150 min in Fe-SAPO-34-HT/PDS system. Meanwhile, the degradation rate constant of Fe-SAPO-34-DGC/PDS system is 0.02391 min -1 , which is approximately 1.6 times higher than that of Fe-SAPO-34-HT/PDS system. The excellent catalytic performance of Fe-SAPO-34-DGC is caused by well dispersed iron-oxide species (the size about 1.47 nm) in cha cage and nanoplate-like morphology as well as mesoporous structure, resulting in the generation of more active sites for PDS activation and faster mass transfer and easier access to active sites. Moreover, the characterized results indicate that the absence of Si(3Al) species is favorable of the formation of nanoplate-like morphology, further leading to the formation of the mesoporous structure because of stacking. Besides, iron-oxide species in Fe-SAPO-34-DGC are confined in cha cage that can effectively keep back its leaching. Furthermore, the possibility of membrane reactor established by Fe-SAPO-34-DGC for practical environmental water treatment was evaluated. Therefore, this method combing in-situ encapsulation method with dry gel conversion technology provides an alternative pathway for construction of iron-based catalysts supported by zeolites to remove organic pollutants through PDS activation.
研究领域:
环境科学
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催化
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材料科学
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化学工程
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高级氧化工艺
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2023
·
IF 5.3
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao,Qiang Wei,Yasong Zhou
SAPO-11 molecular sieves with different crystal sizes and particle sizes, especially nanosized small-crystal SAPO-11 molecular sieves, were successfully synthesized, and the corresponding NiWS-supported catalysts were prepared for the hydroisomerization of n-hexadecane. XRD, SEM, N2 adsorption–desorption, Py-IR, and HRTEM were used to analyze the effects of crystal size and particle size of the supports on their physicochemical properties, active phase properties, and catalytic performance of the catalysts. Through reaction evaluation and analysis of isomeric products, the effects of the size change of the support on the hydroisomerization performance of the catalyst and the hydroisomerization depth of n-hexadecane were determined. Through comprehensive analysis of the cracking products, it was determined that secondary cracking occurred when the conversion of n-hexadecane on the NiW/SAPO-11-S catalyst reached about 42.7%, and the secondary isomerization occurred when the conversion of n-hexadecane reached about 80%. The hydroisomerization reaction network of n-hexadecane over the NiWS/SAPO-11 catalyst was studied emphatically, and it was found for the first time that the secondary cracking of n-hexadecane during hydroisomerization followed the C3-β-scission mechanism.
研究领域:
化学工程
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催化
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材料科学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Qitong Cheng,Benxian Shen,Jichang Liu,Hui Sun,Di Wu,Lei Jiang,Peikun Yan,Xin Pu,Suhui Ou,Jigang Zhao
An alternative and promising route for the production of light olefins which realizes the objective of effective resource usage is the coupling conversion of n -hexane-methanol. The SAPO-34@ZSM-5 core-shell composite has been designed and fabricated by the steam-assisted crystallization (SAC) method for boosting the n -hexane-methanol synergies. SAC avoids the undesired phase transformation/dissolution of SAPO-34 caused by exposure to harsh basic conditions of the ZSM-5 precursor solution. In comparison with the nanosized ZSM-5 or physical mixture, the SAPO-34@ZSM-5 core-shell zeolite demonstrates a 32–38 wt% increase in the light olefin selectivity, a 28–67 wt% increase in the n -hexane conversion, and an 89–143% improvement in the catalyst lifetime under identical reaction conditions. With the aid of GC-MS analysis of carbonaceous deposits in spent catalysts, higher polymethylbenzenes concentration and lower polycyclic aromatic hydrocarbon (PHA) concentration are obtained from the extracted species of spent SAPO-34@ZSM-5 in comparison with that of other samples, which suggests the aromatic-based route to light olefins is enhanced and the carbonaceous deposition is slowed down. The core-shell configuration of the SAPO-34@ZSM-5 composite diminishes the diffusion rate of methanol towards the SAPO-34 core layer and increases the coupling of n -hexane derivatives with methanol in the hydrocarbon pool (HCP) route. The decreased number of acidic sites on the external surface of the SAPO-34 core layer may also be accounted for the inhibited carbon deposition.
研究领域:
化学工程
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催化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 59
·34457-34464
·
IF 3.049
Lingmei Yang,Huiwen Li,Jun ying Fu,Ming Li,Changlin Miao,Zhongming Wang,Pengmei Lv,Zhenhong Yuan
In this article, a novel nano-rod-shaped SAPO-11 molecular sieve (SAPO-11-A-F) with a thickness of ca. 100 nm was successfully fabricated by the in situ seed-induced steam-assisted method using the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a mesoporous template and a nonionic copolymer poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), F127, as the crystal growth inhibitor. The fabricated nano-rod-shaped SAPO-11-A-F possessed nanocrystalline size, a hierarchical porous structure, and enhanced acidic sites. The added CTAB was mainly used to enhance the mesoporous structure and acid, and F127 acted as a grain growth inhibitor. According to the orientation growth mechanism of the molecular sieves, the crystallization mechanism of the nano-rod-shaped hierarchical porous molecular sieves with different crystallization times was investigated. It was found that the nano-rod-shaped molecular sieves were formed by the accumulation of nano-sheets. Compared to three nickel catalysts with different silicoaluminophosphate SAPO-11 molecular sieves in the hydroisomerization of oleic acid to iso-alkanes, the bifunctional catalyst of 7% Ni/SAPO-11-A-F had higher isomeric selectivity (79.8%); in particular, the isomeric octadecane showed stronger selectivity, indicating that the nano-rod-shaped SAPO-11 molecular sieve is more beneficial for the hydrodehydration reaction.
研究领域:
材料科学
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化学工程
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催化
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纳米技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2025
·Vol. 13
·期 36
·30599-30617
·
IF 9.5
Xiaojun Dai,Tingting Liu,Lingjuan Mao,Zixuan Lv
In this work, a SAPO-11 molecular sieve was successfully synthesized via an alcohol–water solvent vapor-induced self-assembly conversion method for the first time. Compared with the conventional hydrothermal crystallization method, the alcohol–water solvent vapor-induced self-assembly conversion method used the induction of alcohol–water solvent steam to drive the solid nucleation and crystallization of the SAPO-11 molecular sieve xerogel precursor. SAPO-11 molecular sieves synthesized by the two methods were used as supports and loaded with NiWS active phase to prepare n-hexadecane hydroisomerization catalysts. The effects of the alcohol–water solvent vapor-induced self-assembly conversion method on the physicochemical properties of SAPO-11 were studied. Compared with the conventional hydrothermal crystallization method, the alcohol–water solvent vapor-induced crystallization method improved the pore structure and acidity of SAPO-11, promoted the dispersion of silicon species in SAPO-11, and inhibited Ostwald ripening during the formation of SAPO-11. The crystallization process of SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method was thoroughly investigated, and the mechanism of the crystallization was discussed. When SAPO-11 synthesized via alcohol–water solvent vapor-induced self-assembly conversion method was used as the support, the MSI of the catalyst weakened and the dispersion and stacking number of the sulfided active phase and the sulfidation degree of the active metals improved. The catalytic results of n-hexadecane hydroisomerization showed that SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method-based catalyst had higher catalytic activity and target product selectivity than the conventional SAPO-11-based catalyst. The catalytic kinetics of the catalysts were investigated in depth. The results showed that the metal site-acid site synergistic catalytic mechanism of SAPO-11 synthesized using the alcohol–water solvent vapor-induced self-assembly conversion method-based catalyst was better than that of the conventional SAPO-11-based catalyst. When SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method was used as the support, the hydroisomerization reaction path priority and hydroisomerization depth of the n-hexadecane hydroconversion over the catalyst improved and deactivation resistance was optimized. The approach is expected to provide a new route and reference for the synthesis of high-performance SAPO-11 molecular sieves and the design of high-efficiency hydroisomerization catalysts.
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 10
·5608-5616
·
IF 7.443
Chan Wang,Miao Yang,Peng Tian,Shutao Xu,Yue Yang,Dehua Wang,Yangyang Yuan,Zhongmin Liu
A spherical self-assembly of SAPO-34 nanosheets was hydrothermally synthesized by using a quaternary ammonium-type organosilane surfactant [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) as the mesoporogen and a part of the silica source, and diethylamine (DEA) as the microporous template. The prepared materials were well characterized by XRD, XRF, SEM, TEM, N2 adsorption–desorption, NH3-TPD, NH3-adsorbed IR and pyridine-adsorbed IR measurements. It revealed that the morphologies, compositions and acidity of the SAPO-34 products changed significantly with the increased TPOAC/TEOS ratio, showing that the TPOAC/TEOS ratio had a significant impact on the crystallization process of SAPO-34. Solid state 13C, 29Si NMR and TG-DTA analyses were further conducted to investigate the status of TPOAC in the final products. A possible crystallization process involving TPOAC was proposed. The catalytic performances of the synthesized SAPO-34s were evaluated using the MTO reaction. The optimal SAPO-34 nanosheet assemblies with a hierarchical porous structure displayed a remarkably enhanced catalytic lifetime and high yields of light olefins.
研究领域:
材料科学
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化学工程
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催化
·
无机化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Xiaohan Wang,Yasong Zhou,Zhiqing Yu,Qiang Wei,Haoran Liu,Jinxiao Sun,Wenbin Huang,Jinquan Tao,Meng Huang
A novel SAPO-11 molecular sieve with a lamellar structure and flower-like morphology was synthesized using cationic surfactant cetyltrimethylammonium bromide (CTAB) as the surfactant and KF as the mineralizer. Meanwhile, the effect of various CTAB additions on the structure and properties of SAPO-11 molecular sieves was also investigated. A number of characterization analyses’ findings reveal that, compared with conventional spherical SAPO-11 molecular sieves, flower-like SAPO-11 molecular sieves have the following advantages: (1) Flower-like SAPO-11 molecular sieves have open pores and larger mesopores, with suitable distribution of mesopores. (2) The prepared flower-like SAPO-11 molecular sieves have a lower total acid value but have a higher proportion of Brønsted acid sites, with suitable acidity. (3) The flower-like NiW/SAPO-11 catalysts have better dispersion of WS2 slabs and higher balance and proximity between metal sites and acid sites. The synthesized flower-like NiW/SAPO-11 showed significant isomerization performance and low cracking selectivity during the isomerization of n-hexadecane. When the conversion rate of n-hexadecane reached 77.0%, the yield of i-hexadecane was 59.4%.
研究领域:
化学工程
·
材料科学
·
催化
·
石油化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Siyuan Zhao,Ke Ma,Kailong He,Xiaoxun Ma,Chengyi Dai
Due to cost and energy consumption constraints, converting benzene into ethylbenzene using low-cost syngas instead of ethylene as an alkylation reagent is significant. However, when using syngas as the reaction raw material, generating ethylated side chains on the benzene ring is challenging. Instead, toluene/xylene becomes the primary product. We used a three-bed series connection method in a reactor, achieving one-step high selectivity of syngas and benzene to produce ethylbenzene. In the first bed layer (ZnAl2O4/SAPO-34), the syngas was first converted into methanol/dimethyl ether (DME) on ZnAl2O4. Then, it was further converted into low-carbon olefins on SAPO-34, with the microporous shape-selective effect of SAPO-34, inhibiting the generation of toluene/xylene in the alkylation of benzene with methanol/DME. At the same time, we proved that the absence of microporous shape-selective effect acid sites on the outer surface of S34 can lead to the occurrence of side reactions of benzene and methanol/DME methylation. In the second bed layer, SAPO-34 could continue to convert unconverted methanol/DME in the first bed layer into low-carbon olefins. In the third layer (ZSM-5), ethylene and benzene underwent highly selective alkylation on ZSM-5 to convert it into ethylbenzene. We found a “volcanic” curve relationship between the selectivity of ethylbenzene and the Brønsted acid site density of ZSM-5. On the one hand, Brønsted acid could catalyze the formation of ethylbenzene from benzene and ethylene; On the other hand, excessive Brønsted acid could lead to the isomerization of ethylbenzene to toluene/xylene. When the Brønsted acid showed a site density of 0.7 mmol/g, the selectivity of ethylbenzene was as high as 87%, with a byproduct of xylene showing only 0.3%, which is usually difficult to separate from ethylbenzene. Finally, the three-bed catalytic system showed no deactivation after 100 h.
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
JOURNAL OF CATALYSIS
·
2024
·
IF 6.5
Peng Zhang,Fangfang Li,Xuefang Yao,Pengze Zhang,Yukai Wu,Mengmeng Xi,Fanhui Meng,Lihua Kang,Mingyuan Zhu
The GaZrO x solid solution has been recently employed in OX-ZEO bifunctional catalysts for efficient conversion of syngas to light olefins, but it remains challenging to identify the specific contributions of Zr and Ga and to understand the detailed reaction mechanisms due to the structural complexity. To address this complexity and elucidate the active sites over the Zr-Ga oxide system, this study presents a catalyst designed by physical mixing ZrO 2 with different crystalline phases ( m -ZrO 2 & t -ZrO 2 ) and α -Ga 2 O 3 . The physical mixture of m -ZrO 2 and α -Ga 2 O 3 achieves a high CO conversion of 39.1 %, with light olefins selectivity of 87.3% among hydrocarbons after combined with SAPO-34, surpassing the performance of physical mixture of t -ZrO 2 and/or α -Ga 2 O 3 with SAPO-34. Combining the various characterizations and DFT calculations, we have confirmed that m -ZrO 2 site, enriched with oxygen vacancies and surface hydroxyl groups, is essential for CO adsorption and HCOO* intermediate formation, while the α -Ga 2 O 3 site plays a key role in the dissociation of H 2 . Furthermore, the electron transfer from m -ZrO 2 to α -Ga 2 O 3 in their mixture is more efficient than in a physically mixed t -ZrO 2 and α -Ga 2 O 3 . This accelerates the H 2 dissociation and boosts the spillover of hydrogen from α -Ga 2 O 3 to m -ZrO 2 , leading to the formation of more CH 3 O* intermediates and higher light olefins yield when combined with SAPO-34.
研究领域:
催化化学
·
材料科学
·
计算化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of CO2 Utilization
·
2018
·
IF 5.503
Jianyang Wang,Anfeng Zhang,Xiao Jiang,Chunshan Song,Xinwen Guo
Although many researchers have reported CO 2 hydrogenation to various C1 chemicals, it is still challenging to directly and selectively convert CO 2 to C 2 -C 4 hydrocarbons in terms of overcoming the extreme inertness of CO 2 and a high C C coupling barrier. In the present work, we report an efficient integration of methanol-synthesis and the methanol-to-hydrocarbons with the bifunctional catalyst component of In 2 O 3 -ZrO 2 and SAPO-5. These tandem reactions exhibit an excellent relative selectivity of C 2 -C 4 (83%) with a suppressed CH 4 relative selectivity less than 3% at T = 300 °C. A detailed analysis indicates that the partially reduced indium oxide surface (In 2 O 3 -ZrO 2 ) can better activate CO 2 and promote the synthesis of methanol than In 2 O 3 alone, and C C coupling is subsequently manipulated within the confined acidic pores of SAPO-5 according to XRD, H 2 -TPR, CO 2 -TPD, SEM and TEM. Furthermore, the proximity of two components and the content of Si also play an important role in such outstanding selectivity to C 2 -C 4 . Our study paves a new path for the direct synthesis of lower hydrocarbons.
研究领域:
化学工程
·
催化化学
·
能源化学
✓ 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）