CRYSTENGCOMM
·
2020
·Vol. 22
·期 37
·6182-6188
·
IF 3.117
Xueshuai Chen,Rongli Jiang,Huilin Hou,Zihan Zhou,Xingwen Wang
ZSM-5/SAPO-34 zeolite composites were successfully synthesized by adding ZSM-5 into SAPO-34 synthetic gel under hydrothermal synthesis conditions, and SAPO-34 as a part of the composite zeolite was synthesized from LAPONITE® as the Si source. The presence of ZSM-5 in the synthetic gel affects the nucleation and crystal growth rate, and core–shell structured zeolite composites can be formed by adding an appropriate amount of ZSM-5. LAPONITE® itself contains Li and Mg atoms which were subsequently introduced into the framework of the SAPO-34 part in the composites via depolymerization–reorganization during the process of crystallization. Furthermore, the depolymerized LAPONITE® can be converted in situ into zeolitic precursors and act as crystalline seeds under hydrothermal conditions. Compared with the ZSM-5/SAPO-34 zeolite composites synthesized from tetraethylorthosilicate (TEOS) instead of LAPONITE® as the Si source, the ZSM-5/SAPO-34 composites synthesized from LAPONITE® exhibited higher selectivity to light olefins and longer lifetime in the MTO reaction. This work provides a convenient route to the synthesis of ZSM-5/SAPO-34 zeolite composites with excellent MTO performance.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2017
·
IF 2.594
Zhichao Yang,Jilong Li,Yunqi Liu,Chenguang Liu
SAPO-11 molecular sieves were synthesized using silica sol, hydrophilic fumed silica , and tetraethyl orthosilicate (TEOS) as silicon precursors. Their physicochemical properties were characterized using XRD , SEM, nitrogen adsorption-desorption, Py-IR, NH 3 -TPD, EDS, and 27 Al, 31 P, 29 Si MAS NMR techniques. The catalytic performance was assessed in the hydroisomerization of n -octane. The results showed that the silicon precursors influenced the physicochemical properties and catalytic performance of SAPO-11. SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor showed higher silicon distribution and had more medium acid sites. SAPO-11 synthesized using TEOS as silicon precursor had more silicon content , but more silicon islands formed in its framework. The depolymerization of silicon precursors might affect the silicon content and distribution in SAPO-11. In the hydroisomerization of n -octane, the catalytic activity strongly depended on the number of medium acid sites instead of the number of total acid sites. SAPO-11 synthesized using hydrophilic fumed silica as silicon precursor exhibited higher catalytic activity than the other samples because it has more medium acid sites.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Guanhua Xing,Siyang Liu,Qingxin Guan,Wei Li
This paper focused on the isomerization and cracking of n -alkanes to synthesize bio-jet fuel. A series of SAPO-11 supports with different Si/Al molar ratio (0.2, 0.4, 0.6) were prepared, characterized, and evaluated by the hydroisomerization on hydrodeoxygenation product of castor oil. As a result, a Ni-Mo/SAPO-11(0.4) catalyst with hollow tubular structure and moderate acidic strength exhibited optimum conversion (97.2%) and jet fuel selectivity (81.6%) in the reaction. Subsequently, Ni-Mo/SAPO-11(0.4) was selected to carry out further experiments on studying the hydroisomerization and hydrocracking of long chain n -alkanes. The results show that increasing temperature may promote hydroisomerization and hydrocracking. Temperature is more favorable for the reaction with the length of the carbon chain decreasing, no matter conversion, hydrocracking degree or isomerization tendency. The product selectivity of different n -alkanes is associated with the carbon number. In reaction to n -C 18 , Ni-Mo/SAPO(0.4) surpassed the other two catalysts in the conversion and i/n ratio at 623 K which is the optimum temperature.
研究领域:
催化化学
·
能源科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Tao Pu,Yanping Li,Xiujuan Yang,Ran Ao,Quxiu Dai,Jie Yang,Zhiying Guo,Liping Ma,Zhanghong Wang
Silicoaluminophosphate-20 (SAPO-20) molecular sieve was synthesized from solid waste coal gangue (CG) and aluminum ash (Al-ash), and its adsorption capacity for CO 2 was evaluated. The content of Si and Al in raw materials was increased by hydrochloric acid pretreatment, and the synthesis conditions (NaOH/CG ratio, calcination temperature, hydrothermal reaction temperature and time, liquid–solid ratio) were optimized by single factor analysis. The synthesized products were characterized by XRD, SEM, BET, FTIR and TEM. The results showed that the SAPO-20 crystal form prepared under the optimal conditions had high purity, BET surface area of 175 m 2 /g, and pore structure with multistage pore distribution, which was conducive to gas diffusion and adsorption. Thermogravimetric analysis revealed that under the conditions of 25 °C and 1 bar, compared with the CO 2 adsorption capacity of 5.63 mg/g for CG, the CO 2 adsorption capacity of SAPO-20 was 27.92 mg/g. The adsorption process was in line with the Langmuir monolayer model and had exothermic characteristics (ΔH = –152 kJ/mol). The adsorption kinetics was fitted by Pseudo-First-Order Kinetic Model (R 2 = 0.740–0.995), and the adsorption rate increased with the increase of temperature. In addition, compared with the traditional synthesis method, the synthesis cost of this study was reduced by more than 70 %, and the carbon emission was reduced by about 75 %, realizing economic and environmental viability.
研究领域:
环境科学
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材料科学
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化学工程
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吸附技术
·
废弃物资源化利用
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2025
·Vol. 155
·期 5
·1-14
·
IF 2.4
Yao Wenjie,Chen Lei,Wang Yinzhong,Yang Gang
The composite molecular sieve catalysts with long reaction times were successfully synthesized by introducing Cu 2+ /Mn 2+ and ZSM-5 into the initial gel. The catalysts were characterized with XRD, SEM and NH 3 -TPD, and further investigated through the methanol-to-olefin reactions. The results showed that the addition of Cu 2+ caused the crystallinity of ZSM-5/SAPO-34 (Z-S) to increase significantly, but with addition of Mn 2+ , the crystallinity gradually decreased. With the increase of the Mn 2+ /Cu 2+ ratio, the desorption summits of the weak and strong acid sites gradually increased, but the weak acid centres gradually dominated, which is herein thought helped reducing formation of the coke. The designed Cu 0.05 -Mn 0.05 /Z-S samples showed beneficial catalytic performances with a lifetime of 1500 min, a 1.5-fold increase compared with the Cu 0.05 /Z-S, while their selectivities remained exceeding 89%. Graphical
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
Small Methods
·
2019
·Vol. 3
·期 5
·1800510
·
IF 0
Dongxu Wang,Jiancong Liu,Xusheng Cheng,Xin Kang,Aiping Wu,Chungui Tian,Honggang Fu
The significant increase of catalytic efficiency while remaining low Pt usage is constantly pursued, but remains a challenge. Here, a “vacuum-assisted” (VA) process toward Pt clusters dispersed on SAPO-11 (S-11) is shown for a high-effective hydroisomerization of n -C 16 . The VA can make effective trapping of the Pt precursor on S-11 due to intensive capillary action, being conductive to stabilize and disperse Pt cluster (≈1 nm) on S-11 (V-Pt/S-11) for promoting synergy of Pt sites and acid sites on S-11. The test indicates excellent catalytic activity and stability of trace Pt clusters (0.15 wt%, even lower, 0.035 wt%) on S-11 (≈94.4% isomer selectivity at 94.3% conversion), much superior to I-0.15 wt% Pt/S-11 from traditional impregnation routes (≈88% selectivity at 90% conversion) and ever reported catalysts. The V-Pt/S-11 is also superior for the hydroisomerization of catalytic diesel oil with a decrease of freezing point up to 40 °C after hydroisomerization. The superior performance is attributed to the exposure of high acid density due to little coverage of Pt cluster on S-11, high dispersion of Pt leading to form more metal–acid bifunctional sites, and enhanced (de)hydrogenation ability of Pt clusters. All of them can promote the effective synergy of metal sites (Pt) and acid sites.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
APPLIED CATALYSIS A-GENERAL
·
2023
·
IF 5.5
Jinbo Zhu,Xu Chen,Xiangge Sang,Gang Yang
SAPO-34 catalysts with high selectivity for light olefins were first synthesized via the introduction of phosphomolybdic acid (HPMo) and AlPO 4 -5 zeolite into the initial gel. The physical and chemical characteristics of the synthesized catalysts were determined by a series of techniques and the catalytic performance of the modified composite zeolites for the methanol-to-olefin (MTO) reaction was investigated. The results indicated that HPMo-modified SAPO-34 was featured with more Brønsted acid sites, more mesopores, and a smaller crystal size, thereby demonstrating superior catalytic performance. The further combination with AlPO 4 -5 (16.7 wt%) prolonged the lifetime of the HPMo-modified SAPO-34, which is thought in this paper related to its 12-ring straight channel (0.7–0.8 nm) and the absence of any Brønsted acid sites. The MTO tests showed that the light olefins selectivity for the modified composite zeolites reached 95.1 %, while the catalyst lifetime remained at 445 min
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2019
·
IF 4.888
Yuhan Ma,Huawang Zhao,Cuijuan Zhang,Yingnan Zhao,Hong Chen,Yongdan Li
Cu-SSZ-13 is a highly active catalyst to remove NO x in the emission of diesel-powered engine. However, the enhancement of its stability in high-temperature (HT) hydrothermal conditions is a well-known challenge in application. This work presents a simple strategy to significantly improve its hydrothermal stability under HT hydrothermal condition by mechanically mixing another CHA type zeolite, Cu-SAPO-34. Both the two zeolites are synthesized via one-pot method, mixed in different ratios, and treated in 10% H 2 O/air at 750 °C for 16 h. The mixed samples are characterized before and after the hydrothermal treatment, and tested in NH 3 -SCR from 150 to 550 °C. The results show the activity of the hydrothermally treated catalysts increases with the increase of the amount of Cu-SAPO-34 up to 50 wt% in the mixed sample. The hydrothermal stability of Cu-SSZ-13 is obviously enhanced by mixing with Cu-SAPO-34. The dealumination is suppressed during the hydrothermal treatment; the framework and the isolated Cu 2+ sites are largely maintained in Cu-SSZ-13. This is attributed to the interaction between the two CHA zeolites during the hydrothermal treatment. We propose the delivery of extra-framework P species from Cu-SAPO-34 to Cu-SSZ-13 is critical to enhance the HT hydrothermal stability.
研究领域:
环境科学
·
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
·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
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2012
·
IF 6.002
Lin Guo,Xiaojun Bao,Yu Fan,Gang Shi,Haiyan Liu,Danjiang Bai
The structure, acidity, and n -octane di-branched isomerization of SAPO-11 synthesized with surfactants of different chain lengths in water–propanol system were investigated. The results showed that with the increasing chain length of surfactants, the crystallite size of SAPO-11 firstly decreased and then increased, but the external surface area and the active B acid sites of SAPO-11 firstly increased and then decreased. The smallest crystallite, the highest external surface area, and the most B acid sites were obtained simultaneously with the surfactant of 12 carbon atoms. The isomerization results of n -octane indicated that among the series Pt/SAPO-11 catalysts, the catalyst with DoTAB-directed SAPO-11 as support had the highest selectivity to di-branched isomers and the lowest cracking selectivity due to the largest external surface area that created more active sites to promote the formation of di-branched isomers by the key-lock mechanism and improve the diffusion of intermediates and products for reducing cracking reactions.
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
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Qibo Liu,Yi Wang,Xiaoguang Sang,Jingce Bi,Ningning Liu,Xia Zhang,Zhuopeng Wang,Yide Han
The agglomeration and leaching of metal species are critical issues for iron-based catalysts to remove tetracycline (TC) through peroxydisulfate (PDS) activation. In this work, iron-oxide species confined in cha cage of silicon aluminum phosphate zeolite (Fe-SAPO-34) was successfully synthesized by in-situ encapsulation method to address the above challenges. In Fe-SAPO-34/PDS system, approximately 92.6% TC was removed within 150 min at experimental conditions: [pH] = 3, [TC] = 20 mg/L, [Catalyst] = 0.10 g/L, [PDS] = 1 mM. Meanwhile, the biggest degradation rate constant is 0.03689 min −1 , which surpasses the counterpart systems. This result originates from the well dispersion of Fe-oxide species in Fe-SAPO-34, providing more active sites for TC degradation. As expected, the Fe-oxide species leaching concentration is ultra-low (0.018 mg/L) in Fe-SAPO-34/PDS system, which is attributed that SAPO-34 has a confinement effect of cha cage and eight-ring pore openings to limit its leaching. The radical quenching tests and electron paramagnetic resonance (EPR) technology verify singlet oxygen ( 1 O 2 ) is the primary reactive oxygen species (ROS) in Fe-SAPO-34/PDS system. Furthermore, two possible pathways for TC degradation are proposed in line with the intermediate identified by liquid chromatography-mass spectrometry (LC-MS).
研究领域:
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
2018
·Vol. 26
·期 3
·793-802
·
IF 1.858
Wu Hong,Wang Xianshu,Liu Fei,Cao Jianxin
The SAPO-34/ZSM-5 composite catalyst (SZ-TS) was successfully fabricated using a two-step in situ crystallization method. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, N 2 adsorption–desorption, and ammonia temperature-programmed desorption measurements were used to characterize the synthesized catalysts and evaluate their catalytic performances on methanol-to-olefin (MTO) reaction. The synthesis mechanism of two-step in situ crystallization was further investigated. Results showed that the SZ-TS synthesized by two-step in situ crystallization featured an intimately bonded composite structure owing to the synergistic effects of the interface. However, the physical mixture of SAPO-34 and ZSM-5 (SZ-PM) presented two discrete phase structures. By using the composite catalyst in MTO reaction, the SZ-TS exhibited the longest life of 1400 min, which was much higher than that of SZ-PM (720 min). Methanol conversion reached 97.3%, and the selectivity for light olefins totalled 93.0%. The excellent catalytic performance of SZ-TS was attributed to the hierarchical pore structure and suitably weak acid site distribution. Via pre-crystallization, alkalinity can be adjusted in the adjacent ranges of SAPO-34 and ZSM-5. By adding the pre-crystallized alkaline SAPO-34 slurry into the strong alkaline system of the parent ZSM-5 slurry, phase dissolution of SAPO-34 in the secondary crystallization solution was avoided. The external surface of SAPO-34 was etched in the alkaline environment of the secondary crystallization solution, resulting in hierarchical pore distribution, which benefited the MTO reaction. This in situ synthesis method features the advantages of simplicity, low time consumption, and low cost. Therefore, this approach possesses the potential to satisfy the demands of the MTO market.
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
危险品化学品经营许可证（带存储）