Reaction Kinetics Mechanisms and Catalysis
·
2021
·Vol. 134
·期 2
·837-849
·
IF 2.081
Zhao Xinhong,Niu Li,Hao Zongyi,Long Xuefeng,Wang Dongliang,Li Guixian
SSZ-13 has been widely used in catalysis and adsorption due to its excellent hydrothermal stability and large specific surface area. It was reported that the long crystallization time was one of the primary challenges limiting its industrial progress. In this paper, we reported a novel solid-state grinding route of synthesizing SSZ-13 zeolite, which was based on interzeolite transformation strategy and promoted by sodium persulfate (Na 2 S 2 O 8 ). The effects of the amount of Na 2 S 2 O 8 and crystallization time on the purity and crystallinity of SSZ-13 zeolite were studied by XRD measurements in detail. The results indicated that the crystallization time could be significantly shortened from 72 to 24 h when the molar ratio of Na 2 S 2 O 8 /SiO 2 was changed from 0 to 0.01, proving that Na 2 S 2 O 8 has the ability of accelerating the crystallization of SSZ-13 as a hydroxyl radical reagent. Three typical SSZ-13 materials and a reference sample were used as the catalysts for methanol-to-olefins reaction (MTO) and their physicochemical properties were analyzed by SEM, N 2 physisorption and NH 3 –TPD techniques. The SEM characterization results showed that the crystal size of SSZ-13 synthesized in the presence of Na 2 S 2 O 8 was larger than that of the one in the absence of it. The NH 3 –TPD results showed that the introduction of Na 2 S 2 O 8 could modulate the acid properties of SSZ-13 zeolites. The MTO tests revealed that the catalytic lifetime of one sample with Na 2 S 2 O 8 promoter (SSZ-13-0.01M-24h) was much longer than that of the other three samples. The observed difference in catalytic stability was mainly attributed to their various concentrations of medium strong acid sites.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Nan Shi,Hengxi Zhu,Jiamin Qi,Bin Li,Jin Zhang
Carbonyl sulfur (COS) was difficult to be removed by conventional desulfurization technologies because of its stable chemical properties. Mesoporous γ-Al 2 O 3 (MA) showed excellent potential for hydrolysis of COS, but the catalyst life was greatly shortened with the progress of the reaction. Therefore, improving the catalyst life is the key to MA which can apply to hydrolysis of COS. In this study, P123 modified mesoporous γ-Al 2 O 3 (P-MA) catalyst was prepared by sol–gel method, and it was regulated by template agent and acidity regulator. These preparation conditions of P-MA were optimized to improve the hydrolysis efficiency of COS. The effects of temperature, space velocity, relative humidity and oxygen concentration for the hydrolysis efficiency of COS were studied. The results show that the optimized P-MA catalyst is suitable for COS low-temperature hydrolysis reaction, and it can maintain 99 % for 10 h under the tough reaction conditions. The only crystal of P-MA was γ-Al 2 O 3 with large specific surface area and uniform distribution pore, which are beneficial to the COS hydrolysis. In addition, the hydrolysis efficiency of COS can also remain 97 % for 10 h in the O 2 and CO 2 atmosphere, indicating that the P-MA catalyst has a specific anti-poisoning ability. The kinetics and reaction mechanism of COS catalytic hydrolysis were studied, which showed that the adsorption of H 2 S was the key to hindering the continuous reaction. The P-MA can effectively inhibit the adsorption of H 2 S, which greatly improved COS hydrolysis life of P-MA. This study provided a theoretical basis for the application of Al 2 O 3 catalyst in the COS hydrolysis.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2019
·Vol. 128
·期 2
·1029-1042
·
IF 1.428
Lu Huihui,Duan Weiting,Zhao Xinhong
A cost-effective route has been developed for the synthesis of nano-sized triclinic SAPO-34 zeolite via seed-assisted grinding method using lower dosage of morpholine as the sole template. The synthesis conditions including silica source, silica concentration, crystallization temperature and time were refined to obtain SAPO-34 zeolite with high phase purity and crystallinity. Particularly, seed crystals preactivated by different methods were utilized to induce the synthesis of nano-sized SAPO-34 zeolites in the subsequent study. The resultant SAPO-34 samples were characterized by XRD, SEM, N 2 physisorption and NH 3 -TPD techniques. It was found that the introduction of seed crystals activated by mechanical milling for 20 min and chemical etching with 0.0001 M and 0.01 M H 3 PO 4 can not only effectively reduce the crystal size of SAPO-34 zeolites from 3–4 μm to 500–800 nm level, but also can modify their texture and acid properties. This nano-sized SAPO-34 catalyst exhibits a remarkably prolonged catalytic lifetime in methanol to olefins (MTO) reaction in comparison to the conventional micron-sized counterpart. Analogous to solvent-free synthesis of zeolites, this seed-assisted grinding synthesis method is simpler, more efficient than conventional hydrothermal synthesis. More importantly, this method provides a new avenue for preparing superior MTO catalyst.
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
RSC Advances
·
2014
·Vol. 4
·期 52
·27259-27266
·
IF 3.708
Libin Yang,Feng Xin,Junzhong Lin,Zhuang Zhuang,Rui Sun
In this study, a hydrothermal synthesis was developed to prepare a thin titanium silicalite-1 catalyst layer in the internal channels of the honeycomb cordierite support, which was used in a continuous heterogeneous reaction. The as-prepared thin TS-1 catalyst layer was characterized by SEM, XRD, UV-vis and ATR-FTIR methods. Multiple hydrothermal syntheses were used for controlling the crystalline growth to optimize catalytic activity and lifetime. Moreover, a monolithic TS-1/cordierite reactor with external looping was utilized to investigate the characteristics of the continuous heterogeneous ammoximation reaction without the organic solvent tert-butanol (TBA). The reaction results showed that the conversion of cyclohexanone and selectivity of oxime approached more than 0.96 and 0.98, respectively. When compared with the reaction using TBA as the reaction solvent, the activity of the monolithic TS-1/cordierite showed no differences except for a longer lifetime.
研究领域:
化学工程
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催化化学
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材料科学
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工业化学
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绿色化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Huiyong Chen,Wenjin Shang,Chenbiao Yang,Baoyu Liu,Chengyi Dai,Jianbo Zhang,Qingqing Hao,Ming Sun,Xiaoxun Ma
The hierarchical layered-bulky ZSM-5 (LBZ5) hybrid composites with a core–shell structure were synthesized by epitaxial growth of layered ZSM-5 nanosheets over bulky ZSM-5 crystals. The systematic balance of zeolitic microporosity and interlayered mesoporosity was achieved by elaborate regulation of the ratio between layered phase and bulky phase, resulting in a series of layered-bulky ZSM-5 hybrid composites with the controllable thickness of the layered shell ranging from 98 to 307 nm. The evaluation of catalytic performance in the methanol-to-propylene (MTP) reaction indicated the LBZ5 materials to be candidated catalysts for the MTP process with prolonged catalytic lifetime, superior coke toleration, and enhanced propylene selectivity compared with the parent bulky ZSM-5 (BZ5) and layered ZSM-5 (LZ5) due to their well-retained zeolitic framework, hierarchical meso-/microporosity by the layered-bulky composite structure, and appropriate strong acidity.
研究领域:
催化
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化学工程
·
材料科学
✓ 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
危险品化学品经营许可证（带存储）