JOURNAL OF POROUS MATERIALS
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2015
·Vol. 22
·期 3
·577-584
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IF 1.108
Zhao Xinhong,Wen Juanjuan,Zhao Jiangbo,Li An,Li Guixian,Wang Xiaolai
Hierarchically structured SAPO-5 molecular sieve was synthesized by microwave-assisted ionothermal method in eutectic mixture solvent. Their porous texture and acid properties were characterized by nitrogen physisorption, SEM, TEM and NH 3 -TPD. The results show that the mesoporous volume of SAPO-5 can be tuned via simply varying the degree of supersaturation, the type of mineralizer or replacing partly succinic acid with sebacic acid. A lower degree of supersaturation and using ammonium fluoride as a mineralizer favor the synthesis of SAPO-5 with large mesoporous volume. Notably, the introduction of sebacic acid can lead to three-level micro-meso-macroporous structure (sample C1). Five typical samples were selected as catalysts and tested in the alkylation of benzene with benzyl alcohol. Among all catalysts, the sample C1, whose aspect ratio is the lowest, exhibited the best catalytic activity, giving a 91 % benzyl alcohol conversion. The diffraction peak intensity ratio of I 002 /I 100 was proposed to be a good indicator in fabricating a highly active SAPO-5 catalyst for this reaction.
研究领域:
化学工程
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材料科学
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DOI
高影响因子
CATALYSIS TODAY
·
2016
·
IF 4.312
Xuesong Liu,Xiaodong Wu,Duan Weng,Zhichun Si,Rui Ran
Cu-modified SAPO-34 molecular sieves with different Cu loading amounts were prepared by ion-exchange and impregnation methods. Both series of catalysts were hydrothermally treated at 750 °C in 10 vol% H 2 O/air for 24 h. The catalysts were characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR), NH 3 temperature-programmed desorption (NH 3 -TPD) and diffused reflectance infrared flourier transform spectroscopy (DRIFTS). All the fresh catalysts show high activity toward the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) at low temperatures regardless of preparation method. Generally, the hydrothermal aging shifts the operation window of the catalysts towards high temperatures. The improvement in high-temperatures activity is attributed to the migration of surface CuO clusters into the ion-exchanged sites as isolated Cu 2+ during ageing, which suppresses the competitive oxidation of NH 3 . The loss of low-temperatures activity is also related to the decrease in the amount of active surface CuO clusters, inhibiting the oxidation of NO to NO 2 and fast SCR reaction. Interestingly, the amount of Lewis acid sites increase linearly with the increasing isolated Cu 2+ , while the Brønsted acidity is weakened.
研究领域:
催化化学
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环境科学
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DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Chao Sun,Aijuan Zhao,Yaquan Wang,Ziyang Wang,Jingjing Zhao,Taotao Zhao,Wenrong Liu,Mingxue Shi,Jiaxin Lu,Shuhui Wu,Lingzhen Bu
Hierarchical SAPO-34 aggregates were hydrothermally synthesized with the assistance of organosilane N-[3-(Trimethoxysilyl)propyl]ethylenediamine (TPED), during which the morpholine was used as the template. The resultant products were characterized by XRD , SEM, ICP-OES, NH 3 -TPD, N 2 adsorption-desorption and TGA , and a possible formation mechanism was proposed. As the amount of added TPED varies, the morphologies, compositions and acid properties of the resultant hierarchical SAPO-34 aggregates differ. The hierarchical SAPO-34 aggregates possessed higher external surface areas, lower Si content, weaker strength and lower concentration in the strong acid sites than the conventional SAPO-34. The investigation of formation process showed that the addition of the TPED had a pivotal role for the formation of hierarchical SAPO-34 aggregates. Compared to conventional SAPO-34, the hierarchical SAPO-34 aggregates exhibited a significant improvement in methanol to olefin reaction (MTO) reactions due to their hierarchical structure and mild acid properties.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
ACS Applied Nano Materials
·
2020
·
IF 0
Jun Wang,Qing Kuang,Xiaofang Su,Xiaowen Lu,Leipeng Leng,Mingyang Zhang,Chunmu Guo,Tong Li,Qian Xu,Shuhui Sun,J. Hugh Horton,Wei Wu,Zhijun Li
Supported single-atom catalysts have become one of the most exciting frontiers in heterogeneous catalysis. The physicochemical properties of these materials are highly interesting; however, the generation of stable single atoms on solid supports is still challenging. Herein, we report an efficient and operationally simple postsynthesis method, consisting of spatial confining, freeze-drying, and reducing steps, for the construction of singly dispersed palladium atoms on SAPO-31 (Pd1/SAPO-31) with promising application prospects in the semihydrogenation of alkynes. A typical Pd–N–C single-atom catalyst derived from the ZIF-8-supported palladium complex was prepared and compared to Pd1/SAPO-31. The Pd1/SAPO-31 catalyst showed outstanding performance in the semihydrogenation of both phenylacetylene (85% selectivity at 99% conversion, 40 min) and 1-chloro-4-ethynylbenzene (95% selectivity at 99% conversion, 60 min). In addition, this single-atom palladium catalyst was highly active in triethoxysilane oxidation. Most importantly, this catalyst retained its atomic dispersion and catalytic activity after high-temperature thermal treatment in Ar at 700 °C. This study demonstrates how zeolites can be used to confine atomically dispersed metal species and tune the activity and stability of these materials to meet the needs of practical applications.
研究领域:
催化化学
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材料科学
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DOI
ENERGY & FUELS
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2021
·
IF 3.605
Meiqiu Hu,Xiaolong Liu,Hong Yuan,Jingye Ma
An in situ encapsulation process was used to prepare ordered worm-like mesoporous Pt@SAPO-11 catalysts with different Pt loadings. Transmission electron microscopy images showed that Pt nanoparticles encapsulated within the SAPO-11 support mesopores were uniformly distributed and highly dispersed and had a narrow particle size distribution of 2–7 nm. Scanning electron microscopy indicated that increasing the Pt loading from 0.6 to 1.6 wt % did not significantly change the crystalline morphology of the catalyst, although the crystallinity decreased slightly. The specific surface area and average pore diameter of the Pt@SAPO-11 were in the ranges of 72–116 m2/g and 8.1–9.5 nm, respectively, which are determined by the Brunauer–Emmett–Teller method and Barrett–Joyner–Halenda method, respectively. The NH3 thermal-programmed desorption established that increasing the Pt loading gradually decreased the total NH3 desorption and that a loading of 1.2 wt % produced the highest concentration of medium-strong acid sites (6.2 cm3/g STP). X-ray photoelectron spectroscopy and H2 temperature-programmed reduction showed that a Pt loading of 1.2 wt % gave the strongest interaction between Pt nanoparticles and the SAPO-11 support. The Pt@SAPO-11 catalysts were used for the preparation of C8–C17 alkanes by decarboxylation of oleic acid. Employing a reaction temperature of 340 °C, a CO2 atmosphere, a Pt loading on the catalyst of 1.2 wt %, and a reaction time of 4 h, 100% oleic acid conversion was obtained together with an 80% yield of C8–C17 alkanes.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2023
·Vol. 10
·期 13
·3874-3883
·
IF 7
Xiaosi Zhang,Miao Yang,Ye Wang,Caiyi Lou,Shutao Xu,Peng Tian,Zhongmin Liu
Seed-assisted synthesis shows great potential to modify the properties of inorganic microporous materials and enhance synthetic efficiency. However, the understanding of the related mechanism is insufficient, especially in silicoaluminophosphate (SAPO) molecular sieve systems. In this work, the seed-assisted synthesis of SAPO-34, an important industrial methanol-to-olefins (MTO) catalyst with CHA topology, was investigated by using various seeds with different structures, compositions and morphologies. It reveals that both double 6-ring (d6r) units and complex Si environments are key features for a highly effective SAPO seed, which may provide small fragments containing complete or broken d6r units with Si–O–Al domains after the dissolution of seeds and thus derive the nucleation and crystallization of SAPO-34. Moreover, small crystal size and high Si content are positive factors for a qualified SAPO seed. Heteronuclear seeds, such as SAPO-18, SAPO-35 and SAPO-56, have been found to be effective for the synthesis of SAPO-34 with improved MTO catalytic performance. For SAPO materials without d6r units, their effect strongly depends on the growth solution and there is no preferential phase selectivity for SAPO-34. These findings could prompt the efficient synthesis and property control of SAPO molecular sieves.
研究领域:
材料科学
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催化化学
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DOI
高影响因子
Catalysts
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2018
·Vol. 9
·期 1
·16
·
IF 3.465
Yuehong Yu,Jiaxiang Qin,Min Xiao,Shuanjin Wang,Dongmei Han,Yuezhong Meng
Introducing mesopores into the channels and cages of conventional micropores CHA (Chabazite) topological structure SAPO-34 molecular sieves can effectively improve mass transport, retard coke deposition rate and enhance the catalytic performance for methanol to olefins (MTO) reaction, especially lifetime and olefins selectivity. In order to overcome the intrinsic diffusion limitation, a novel CO2-based polyurea copolymer with affluent amine group, ether segment and carbonyl group has been firstly applied to the synthesis of SAPO-34 zeolite under hydrothermal conditions. The as-synthesized micro-mesoporosity SAPO-34 molecular sieve catalysts show heterogeneous size distribution mesopores and exhibit slightly decrease of BET surface area due to the formation of defects and voids. Meanwhile, the catalysts exhibit superior catalytic performance in the MTO reaction with more than twice prolonged catalytic lifespan and improvement of selectivity for light olefins compared with conventional microporous SAPO-34. The methodology provides a new way to synthesize and control the structure of SAPO-34 catalysts.Keywords:molecular sieves;SAPO-34;MTO;CO2-based polyuria;mesoporogen
研究领域:
化学工程
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材料科学
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DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xiaohe Wang,Hongwei Chen,Maosheng Zhang,Chaoran Wang,Yufei Wang,Pu Bai,Libo Li,Wenfu Yan
Silicoaluminophosphate (SAPO) zeolites as one of the most important members of zeolitic materials, providing equally high adsorption capacity of CO 2 as aluminosilicate zeolites, can be used as promising candidate materials for selective adsorption and separation of CO 2 . In this work, desirable from both economic and environmental viewpoints, a green and cost-effective one step synthesis strategy of K-SAPO-34 zeolite was developed in a wholly inorganic system under hydrothermal conditions. The pure K-SAPO-34 crystals can be obtained in a wide range of initial gel compositions. The as-synthesized K-SAPO-34 has high proportion of framework Si (Si / (Si + Al + P) = 0.37) and framework charge density ((Al – P) / (Si + Al + P) = 0.36). Because the presence of silica islands in K-SAPO-34 framework leads to a decrease in the number of extra framework cations per unit cell, the K-SAPO-34 in this work has a high CO 2 adsorption capacity (64.1 cm 3 /g) than the conventional K-SAPO-34 prepared by ion-exchange (1.9 cm 3 /g). Moreover, the K-SAPO-34 in this work has a superior separation performance for CO 2 /N 2 and CO 2 /CH 4 .
研究领域:
材料科学
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环境科学
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Ying Wang,Fei Liu,Mengqin Yao,Jun Ma,Shuo Geng,Jianxin Cao,Xiaodan Wang
Promoting the efficient formation of methanol intermediates during CO 2 hydrogenation to lower olefins plays a decisive role in improving the catalytic performance of a tandem catalyst. In this study, a series of chromium (Cr)-modified gallium–zirconium oxides with the formula GaCrZrO x (y%) were prepared via the sol–gel method. The characterization and experimental results show that the addition of moderate amounts of Cr not only facilitates the formation of more oxygen vacancies on the surface of GaZrO x but also strengthens the adsorption and activation ability of CO 2 and H 2 , thereby promoting the generation of formate and methoxy intermediates. After coupling with SAPO-34 zeolite, the methanol intermediate produced on GaCrZrO x (y%) is rapidly converted into lower olefins. This integration manner oxide and zeolite catalysts is particularly important for catalytic performance because an appropriate affinity between components can induce the formation of methanol intermediates via the kinetic effect, which limits the reverse water–gas shift reaction at high temperature. The GaCrZrO x (3.0 %)/SAPO-34 tandem catalyst synthesized via grinding and mixing at 390 °C and 3 MPa exhibits remarkable stability and catalytic performance, achieving a CO 2 conversion close to 30 %, a lower olefin selectivity of 85.8 %, and a lower olefin yield of 11.7 %.
研究领域:
催化化学
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材料科学
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环境科学
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产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Weijiong Dai,Zongqiang Liu,Jing Zhao,Yan Wang,Jiajun Zheng,Ruifeng Li
SAPO-34 zeolites with excellent selectivity towards to light olefins and highly catalytic stability are highly desirable. In this work, SAPO-34 zeolite (SAPO-34-S-F) featuring both significantly reduced crystal dimension and a hierarchical structure was synthesized for the first time through a seed-assisted strategy employing cost-effective triethylamine (TEA) as the only organic structure-directing agent (OSDA) in the NH 4 F-containing medium. The resulting SAPO-34 zeolite demonstrated exceptional catalytic performance in methanol-to-olefin (MTO) reaction, exhibiting a substantially increased catalytic lifetime of 525 min as well as an impressive light olefin selectivity of up to 83.7 %. These results significantly outperform those of conventional SAPO-34 zeolite with larger crystal dimension synthesized using TEA as OSDA, and SAPO-34 zeolite with similar crystal dimension synthesized without fluoride addition. Thermogravimetric analysis (TGA) of the spent catalysts revealed that SAPO-34-S-F possesses enhanced coke tolerance. Furthermore, in situ UV/Vis studies of the organic intermediates generated on zeolites during MTO reaction provided additional evidence for the excellent catalytic activity and stability of the SAPO-34-S-F sample. These findings offer important insights for the rational development of stable and high-efficiency SAPO-34 zeolite for MTO reaction.
研究领域:
材料科学
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催化化学
·
能源化工
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
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2018
·
IF 3.956
Ping Zhang,Haiyan Liu,Yuanyuan Yue,Haibo Zhu,Xiaojun Bao
Hydroisomerization of light straight-chain paraffins to their branched isomers especially di-branched ones is considered as a promising technology to produce clean gasoline blending component with high octane number . In this article, we report a superior hydroisomerization catalyst that is based on a SAPO-11 molecular sieve (SAPO-11-H) simultaneously with smaller crystal size, hierarchical pore structure and enhanced acidity. This novel SAPO-11-H was successfully synthesized via a two-stage hydrothermal crystallization route by simultaneously using a cationic surfactant cetyltrimethylammonium bromide (CTAB) as template and a nonionic copolymer poly(ethylene oxide)‑ block ‑poly(propylene oxide)‑ block ‑poly(ethylene oxide) (F127) as crystal growth inhibitor . During the crystallization, CTAB plays roles in enhancing the acidity and creating the mesoporous structure, and F127 serves as a crystal growth inhibitor to control the crystals size. Compared to two Pt catalysts supported on a conventional SAPO-11 and a commercial SAPO-11, the SAPO-11-H supported Pt/SAPO-11-H catalyst with the same Pt loading (0.5 wt%) exhibited superior selectivity to di-branched C 8 isomers and dramatically lower cracking selectivity in n ‑octane hydroisomerization. The outstanding performance of Pt/SAPO-11-H is mainly attributed to two factors: one is the highly exposed pore mouths and hierarchical pore structure of SAPO-11-H that benefit the formation of di-branched isomers and avoid the cracking of the resultant di-branched isomers, and the other is the enhanced acidity that boosts the hydroisomerization activity.
研究领域:
化学工程
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催化材料科学
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产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2024
·
IF 2.3
Li Shengpeng,Cheng Shimin,Yuan Long,Tan Guangyu,Cheng Ying,Li Li,Li Yichen,Wang Chuang
In this study, nano-sheet SAPO-34 molecular sieves were synthesized using an aminothermal method. Triethylamine (TEA) was used as the major solvent and template, along with varying amounts of tetraethylammonium hydroxide (TEAOH). Physicochemical properties of the synthesized catalysts were characterized by techniques of XRD, SEM, BET, XRF, and NH 3 -TPD. As the amount of TEAOH increases, the composition of the product changes from a mixture of SAPO-5 and SAPO-34 to pure nano-sheet SAPO-34 molecular sieves. A TEAOH increment causes a reduction in crystallinity and particle size, as well as an increase in acid sites. Additionally, there is a non-linear relationship between the silicon content in molecular sieves and the amount of TEAOH added in the system. In the conversion of methanol to olefins using various SAPO-34 catalysts, the nano-sheet samples with the highest crystallinity and moderate acidity exhibited the longest lifetime and higher selectivity to C 2 = + C 3 = olefins. Graphical Abstract
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
危险品化学品经营许可证（带存储）