RSC Advances
·
2017
·Vol. 7
·期 60
·37787-37796
·
IF 3.108
Xuesong Liu,Xiaodong Wu,Duan Weng,Zhichun Si,Rui Ran
Cu/SAPO-34 catalysts were prepared by wet impregnation and ion-exchange methods, and both the catalysts were hydrothermally treated at 750 °C in 10 vol% H2O/air for 24 h. Subsequently, the as-received and hydrothermally treated catalysts were exposed to a sulfur poisoning treatment at 350 °C in 100 ppm SO2/10 vol% H2O/air for 24 h and examined for NOx conversion. Sulfur poisoning considerably decreased the NOx conversion efficiency of the catalysts at low temperatures. In contrast, it improved the high-temperature selective catalytic reduction (SCR) activities of the as-received catalysts. The ion-exchange-prepared catalysts displayed higher sulfur tolerance than the impregnation-prepared catalysts at 150–350 °C. The electron paramagnetic resonance, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and H2-temperature-programmed reduction results showed that sulfur poisoning significantly influenced the migration of the copper species and thereby the amount of active isolated Cu2+. More dispersed CuSO4 was produced on the ion-exchange-prepared catalysts than on the impregnation-prepared catalysts after sulfur poisoning. The dispersed CuSO4 showed considerably higher SCR activity than the crystalline CuSO4. Both the dispersed CuSO4 and remaining isolated Cu2+ determined the low-temperature SCR behavior of the sulfur-poisoned catalysts.
研究领域:
催化化学
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环境科学
✓ 已验证
DOI
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2019
·Vol. 2020
·期 3
·318-326
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IF 2.578
Mingjian Luo,Mingxu Liu,Yadong Fu,Wenxin Chen,Baohui Wang,Guoliang Mao
Graphical Three-stage SAPO-34s have higher purity, smaller crystal size, more acidic sites, longer catalytic lifetime and better olefin selectivity. The crystallization mechanism and the relationship between properties and performance are discussed. Acidity and 2–4 nm mesopores have little effect on MTO performance, which mainly depends on the size and dispersity of the crystallites and the purity of SAPO-34. SAPO-34 zeolites were synthesized by one-, two-, and three-stage crystallization processes with fumed silica (FS), acidic silica sol (AS), basic silica sol (BS) and tetraethoxysilane (TEOS) as silicon sources. Properties of samples were characterized by XRD, SEM, EDX, N 2 -adsorption/desorption, NH 3 -TPD and 29 Si NMR. In contrast with one- and two-stage processes, the three-stage one favors the formation of SAPO-34s with higher purity, higher Si/Al ratio, smaller crystallite/crystal size, better dispersion and more acidic sites. Crystallization mechanism was proposed. It is supposed that three-stage process favors the formation of high supersaturated SBUs (secondary building units) and CBUs (composite building units) before nucleation. Thus massive nuclei are formed during nucleation and well-dispersed small size SAPO-34 crystals are formed in three-stage process. Three-stage SAPO-34s are longer catalytic lifetime and better olefin selectivity in MTO process. TEOS-3 has the best MTO performance. It was found that acidity of sample and mesopores in 2–4 nm range have little effect on the MTO performance of SAPO-34. Catalytic lifetime and olefin selectivity are mainly depending on the size of crystallites, the dispersity of crystallites, and the purity of SAPO-34.
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
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
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2020
·Vol. 2020
·期 22
·2170-2176
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IF 2.529
Xueshuai Chen,Rongli Jiang,Zihan Zhou,Xingwen Wang
Graphical SAPO-34 zeolite was successfully synthesized from laponite as the single Si source. Laponite itself contains Li and Mg atoms, which were subsequently introduced into the structure of SAPO-34 via depolymerization-reorganization of laponite. Metal incorporation can reduce the amount of stronger acid sites and enhance the catalytic performance in the MTO reaction. In this work, SAPO-34 zeolite with high catalytic activity was successfully synthesized by hydrothermal method from laponite as the single Si source. Compared with the traditional method of synthesizing zeolites from clay, the laponite after swelling can be directly used in the synthesis process of zeolite. The crystallization behavior of SAPO-34 synthesized from laponite was investigated by XRD, FTIR, N 2 adsorption–desorption, SEM-EDX, ICP-MS, and DR-UV/Vis. The process can be summarized as follows: the Si and Mg elements were produced by the depolymerization of laponite, then the primary building units of SAPO-34 zeolite were formed under hydrothermal conditions; finally, the crystal nucleus began to form, and crystallization was triggered. Compared with the conventional SAPO-34 synthesized from TEOS, the SAPO-34 synthesized from laponite exhibited higher selectivity to light olefins and longer lifetime, which can be attributed to the suitable strength of acidity. This work points to a straightforward route to the synthesis of SAPO-34 from laponite.
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Taotao Zhao,Chenyang Shen,Gui Liu,Jun Yao,Xianghao Wang,Huajie Tao,Yu He,Yuchi Liu,Zhewei Zhang,Feifei Mei,Xiangke Guo,Luming Peng,Yan Zhu,Xuefeng Guo,Nianhua Xue,Weiping Ding
We report here a high-performance catalyst ReMoS x @HSSZ-39 compounded with SAPO-34 for conversion of CO 2 to C 2-4 hydrocarbons, in which the ReMoS x clusters are responsible for highly efficient hydrogenation of CO 2 to methanol as the intermediate and then the surrounding zeolitic acid sites for further conversion of methanol to hydrocarbons. The investigation finds that uniform ReMoS x clusters can be reliably fabricated in zeolitic cages by co-introduction of rhenium and molybdenum species into the HSSZ-39 zeolite and followed by sulfidation, which constitutes an intimate bifunction catalyst through better cooperation of ReMoS x clusters and the zeolitic acid sites. Compared with MoS x @HSSZ-39, the introduction of rhenium significantly suppresses CO generation. By mixing some SAPO-34 zeolite, with increased density of protonic acid, more than 86 % C 2-4 hydrocarbons in organic products and only 21 % CO at 32.5 % of CO 2 conversion are obtained and the composite catalyst shows excellent stability with more than 95 % C 2-4 hydrocarbons in organic products, less than 30 % CO and above 26.6 % of CO 2 conversion after 1000 h on stream.
研究领域:
催化化学
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Reaction Chemistry & Engineering
·
2024
·
IF 3.4
Haobin Hu,Ke Ma,Zhenyu Cheng,Xinyu Qi,Haiyan Song,Zhijun Li,Yufeng Wang,Penghui Zhang,Chengyi Dai,Xiaoxun Ma
The methanol-to-olefins reaction is a viable and promising technological route to replace increasingly scarce petroleum resources. SAPO-34 zeolite is an ideal catalyst for the methanol-to-olefins reaction due to its suitable acidity and pore structure. However, a single zeolite catalyst has limited performance, and in this work, metal species were introduced on SAPO-34 molecular sieves to achieve higher low-carbon olefin selectivity through the modulation of acidity. However, since the introduction of metals promotes aromatic cycling, it allows the creation of carbonaceous precursors and reduces the catalyst lifetime. Therefore, the introduction of CO2 into the carrier gas inhibited the generation of carbonaceous precursors and thus prolonged the catalyst life. The presence of the metal species and their effects on SAPO-34's pores and structure were characterized by XPS, the change in acid amount was determined by NH3-TPD, and the adsorption strength of the catalyst for CO2 was determined by CO2-TPD, revealing the active sites of the catalyst. High low-carbon olefin selectivity and long catalyst life were also achieved, with low-carbon olefin selectivity of 88.0%.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2021
·Vol. 11
·期 5
·616
·
IF 4.146
Li Han,Xinxin Yan,Lulu Guo,Yanan Duan,Zheng Wang,Tianliang Lu,Jun Xu,Yuzhong Zhan,Jianfeng Wang
A triclinic SAPO-34 molecular sieve was synthesized ionothermally. The as-synthesized products were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), nuclear magnetic resonance (NMR), fourier infrared spectrometer (FT-IR) and thermogravimetric (TG) analyses. The formation mechanism of the hierarchical porous triclinic SAPO-34 zeolites and the factors affecting the morphology of the SAPO-34 molecular sieve were investigated. The results show that the formation mechanism of the hierarchical pores is in accordance with Ostwald ripening theory, and the accumulation of grains constitutes the existence of mesopores and macropores. The crystallization temperature, ionic liquid type, and organic amines can effectively change the morphology and crystallinity of the SAPO-34 molecular sieve. The crystallization temperature, ionic liquid and template have great influence on the (111) crystal plane, thus affecting the morphology of the molecular sieve. Moreover, it can be proven through NMR and TG analyses that ionic liquids and organic amines can be used as structure directing agents together.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2022
·
IF 5.477
Tao Zheng,Peng He,Rui Zhang,Xianghai Meng,Yuanyuan Yue,Hongtao Liu,Zhichang Liu,Chunming Xu,Haiyan Liu
Background In the past decades, seed-assisted synthesis of zeolites has become one of the research focuses. Understanding the effect of the seeds on their derived products, and thus tuning the physicochemical properties of those products by selecting suitable seeds is pivotal for synthesizing zeolites via seed-assisted method. Methods In this work, four kinds of SAPO-34 with different physicochemical properties were synthesized and used as seeds to prepare their corresponding products via the seed-assisted method. The physicochemical properties of the seeds and the corresponding products were characterized by XRD, SEM, N 2 adsorption-desorption, NH 3 -TPD, and 29 Si MAS NMR techniques. Significant Findings The results showed that the particle size, textural and acidity properties, and the silicon coordination of the seed-derived products are strongly correlated to their corresponding seeds, exhibiting genetic effects. By investigating the crystallization kinetics, we speculated that the genetic effects should be attributed to the incomplete dissolution of the seeds. During the crystallization process, the incompletely dissolved seed fragments are directly incorporated into the product and serve as models. These models then require the final zeolites to grow according to their patterns, retaining and inheriting their original characteristics.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Xiaoming Zhou,Zhuoyuan Chen,Zhiyong Guo,Haiping Yang,Jingai Shao,Xiong Zhang,Shihong Zhang
A series of dual metal incorporated CuCex-SAPO-34(x = 0–0.04) samples were synthesized using one-pot hydrothermal method with diethylamine as organic structure-directing agent for selective catalytic reduction of NO x by NH 3 . The catalytic properties were elucidated in detail with physicochemical properties being analyzed using various instruments. All the catalysts exhibited typical SAPO-34 crystal structures with high specific surface areas. With the dual-metal incorporation, the surface acidity and amount of isolated Cu 2+ , which may be active sites for NH 3 -SCR, were significantly enhanced. However, excessive Ce restrained the formation of isolated Cu 2+ due to its occupation of cationic sites. Therefore, the 0.05CuCe0.02-SAPO-34 exhibited high NO conversion (≥80%) at 168°C-500°C. Furthermore, the NH 3 -SCR mechanism over different catalysts was investigated in-situ DRIFTS experiments. For the 0.05Cu-SAPO-34, the adsorbed NH 3 species react with gaseous NO and following the E-R mechanism throughout the reaction temperature range. Meanwhile, adsorbed NO 2 was detected and reacted with the adsorbed NH 3 species according to the L-H mechanism in low-temperature region. In contrast, the NH 3 -SCR reaction over the 0.05CuCe0.02-SAPO-34 primarily followed the E-R mechanism throughout the temperature range. The L-H mechanism was cut off due to the loss of the adsorption ability of nitrous species at high temperatures., resulting in NO conversion decreasing.
研究领域:
环境科学
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材料科学
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产品关联
DOI
PubMed
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
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
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2021
·
IF 3.498
Shichao Zhang,Wenbin Chen,Ling Yang,Tong Xie,Weike Li,Daoke Yu,Yiwen Fang
SAPO-34 molecular sieve is one of the main catalysts for DMTO reaction and shows excellent catalytic performance. In this work, a series of Ni-SAPO-34 molecular sieve with different crystal morphologies , such as cubic, melting angle cube , spherical, polygon cube, were synthesized using Ni-DETA as a structure-directing agent. We explored the influence of Ni-DETA structure-directing agent on the formation of crystal morphology, and found that the different morphology is related to the amount of Ni-DETA introduced, and also had an impact on the acidity of the Ni-SAPO-34 molecular sieve. The properties of these samples were characterized by SEM, XRD , EDS, UV–Vis, FT-IR, NH 3 -TPD and N 2 physicalsorption. The synthesized polygonal cubic Ni-SAPO-34 molecular sieve has lower strong acidity due to the introduction of a small amount of nickel, which is beneficial to reduce the production of carbon deposits and improve the catalytic reaction activity. Moreover, the multi-edge morphology and hierarchical porous structure are also advantageous to the catalytic reaction. The polygon cube Ni-SAPO-34 catalysts display the highest DTO catalytic performance, and the total selectivity of ethylene and propylene can reach 83.76%.
研究领域:
化学工程
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材料科学
✓ 已验证
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
✓ 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
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材料科学
✓ 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）