ENERGY & FUELS
·
2022
·
IF 4.654
Nini Zhang,Sheng-Li Chen,Ruyue Zhu,Wei Sun
In this work, we found that besides formaldehyde, an important intermediate in methanol-to-olefins (MTO) conversion, acetaldehyde and acetone were also formed in the MTO reaction and accurately quantified their contents in the reaction system with time on stream. The formation of formaldehyde, acetaldehyde, and acetone follows a sequential reaction. Acetaldehyde could induce the formation of aromatic species, promoting the conversion of lighter aromatic species across cages to polycyclic aromatics and further promoting the formation of insoluble coke, resulting in rapid catalyst deactivation. In addition, acetaldehyde enhances the propagation of the aromatic-based cycle, which leads to the formation of ethylene, thus resulting in the high ethylene selectivity. In contrast, acetone has little effect on the working lifetime of the catalyst and the product distribution of the MTO reaction, although it can be converted to light hydrocarbons similar to that of MTO under the circumstance of the MTO reaction.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Lei Zhao,Ge Yang,Haocheng Hu,Yuhao Sun,Zhuang Ma,Peng Peng,Eng-Poh Ng,Peng Tian,Hailing Guo,Mintova Svetlana
The nanosheet SAPO-34 zeolite crystals with a diameter of 300 nm and a thickness of 50 nm using a new phosphorus source (pyrophosphoric acid, H 4 P 2 O 7 ) were synthesized. The roles of the pyrophosphate (P 2 O 7 4− ) species in the crystallization of SAPO-34 were elucidated. The results suggested that one P atom from the P 2 O 7 4− species participated in the formation of the CHA framework structure while the other P atom served as a crystallization control agent, facilitating preferential crystal growth in [100] crystal plane. The SAPO-34 nanosheets have silica-rich shell and phosphorus-rich core leading to superior catalytic performance in methanol-to-olefin reaction (MTO). The catalytic lifetime of the SAPO-34 nanosheets was significantly improved due to the larger amount of medium-strong surface acidity and short diffusion pathway in comparison to the conventional SAPO-34 catalyst synthesized in the presence of the classical phosphorus source (H 3 PO 4 ).
研究领域:
材料科学
·
催化化学
✓ 已验证
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
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Wei Huang,Huifang Wu,Xin Yan,Jiaxing Zhang,Zhaochi Feng,Miao Yang,Peng Tian,Xinwen Guo,Limin Ren
Nine-membered-ring (9-MR) STT zeolites hold immense potential in studying the impact of pore structure on catalytic performance. However, synthesizing pure-phase STT zeolites with tunable acid sites has been challenging. This study presents a rational approach for the rapid synthesis of STT zeolites from lamella Si-MWW zeolite via a chain rearrangement process, leveraging their structural similarities and the flexibility in manipulating MWW’s layer structure. Both zeolites share a common chain comprising ordered arrangements of 4-, 5-, and 6-membered rings, facilitating robust and rapid (10 h) STT growth, with a broad Si/Al ratio range. The resulting Al-STT zeolites exhibited an olefin product distinct from the 8-MR CHA and 10-MR MFI zeolites in the methanol-to-olefin reaction, underscoring the pivotal role of 9-MR pore structure. The findings not only advance the understanding of zeolite synthesis but also demonstrate the potential of tailoring pore structures to enhance the catalytic efficiency in industrially relevant processes.
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
Inorganic Chemistry Frontiers
·
2024
·Vol. 11
·期 5
·1596-1606
·
IF 6.1
Dehua Wang,Minghui Mo,Man Xu,Zhijun Xia,Xuebin Zhao,Beibei Gao
Seed-assisted synthesis of nano-SAPOs usually requires a costly nano-sized seed, and the micron-sized seed used should be ball-milled or treated under reflux to broke them into nano-particles. In this study, nano-sized SAPO-34 was prepared using a micron-meter SAPO-34-M seed that was treated facilely with morpholine (MOR) within a Teflon-lined stainless steel autoclave to obtain a seed solution. As MOR was also the template for SAPO-34 synthesis, no extra template was added to the precursor gel. The effects of MOR treatment time on seed properties and the subsequent SAPO-34 fabrication were characterized via XRD, SEM, N2 adsorption–desorption, 29Si NMR and NH3-TPD techniques. The effect of the seed amount on the products was also investigated. There existed optimum seed treatment time and seed addition amount for synthesizing uniform nano-sized SAPO-34 with the characteristics of larger mesopore volume, lower Si contents and acid density and weaker acid strength than conventional SAPO-34. Moreover, heterologous seed-assisted syntheses of SAPO-34 were carried out, and it is found that micron-sized heterologous seeds (AFI, RHO, LEV and AFX) treated with MOR can also deliver nano-sized SAPO-34, although AFI and RHO share no common composite building units (CBUs) with CHA, suggesting that seed selection in this synthesis strategy is not confined to a specific topology. The obtained nano-sized SAPO-34 catalysts exhibited about a 2.7-fold prolonged lifetime and nearly 5% increased selectivity for ethylene and propylene compared to their conventional micron-sized counterparts in methanol-to-olefin (MTO) reactions.
研究领域:
材料科学
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催化化学
·
能源化学
✓ 已验证
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
✓ 已验证
DOI
高影响因子
CATALYSIS LETTERS
·
2021
·Vol. 152
·期 6
·1651-1659
·
IF 3.186
Tao Lei,Zhang Xueliang,Song Lizhu,Hu Huilin,Liu Lequan,Ye Jinhua,Wang Defa
As one of the most promising routes for production of low-carbon olefins (e.g., ethene and propene etc.), methanol-to-olefins (MTO) reaction is influenced largely by the temperature. Noble metal (e.g., Au, Ag, etc.) nanoparticles are known to exhibit the localized surface plasmon resonance (LSPR) effect, which has been applied in photothermal reactions. Owing to the increased light absorption ability in near-infrared region, titanium nitride (TiN) nanoparticles exhibit a superior LSPR effect over noble metals. Herein, we report on the MTO reaction via photothermal effect over a series of TiN(x)/SAPO-34 (x = 0.5, 0.75, 1, 2, 5, 10, 13 wt%) catalysts prepared by a simple mechanical grinding method. The MTO reaction over TiN(x)/SAPO-34 was carried out under a 300 W xenon lamp irradiation. The MTO reactivity of TiN(x)/SAPO-34 was influenced by both the photothermal temperature from the LSPR effect of TiN nanoparticles and the Brønsted acid sites on SAPO-34, both of which were dependent on the loading amount of TiN nanopartiles. The synergistic effect of high photothermal temperature, sufficient Brønsted acid sites and moderate BET surface area gave rise to the optimal catalytic performance of MTO reaction over TiN(10)/SAPO-34, which exhibited a methanol conversion of 73.1% and an ethene selectivity of 62.5%. Graphic Abstract
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2025
·
IF 9.5
Jianfei Xiao,Jifei Ma,Zhenliang Zhu,Yao-Qi Huang,Shaojun Yuan
The separation of methanol-to-olefins (MTO) products to obtain high-purity ethylene (C₂H₄) and propylene (C₃H₆) is a critical yet challenging task. However, developing adsorbents with high C₃H₆/C₂H₄ selectivity and productivity for one-step C₂H₄ purification and C₃H₆ recovery remains an industrially significant but demanding objective. In this study, a site-engineering strategy was employed to tailor cage size and polarity within a confined pore space. Using post-synthetic modification, the robust Zr-based metal-organic framework (MOF-808) was functionalized with oxygen- and benzene ring-containing ligands, including benzoic acid (Ben), 2-formylbenzoate (For), and 2-acetylbenzoic acid (Ace). Among these, MOF-808-For exhibited a twofold increase in both C₃H₆ adsorption capacity (5.7 mmol·g⁻¹) and C₃H₆/C₂H₄ separation efficiency compared to unmodified MOF-808 under identical conditions. Additionally, MOF-808-For enabled the simultaneous recovery of C₃H₆ and C₂H₄ through a one-step adsorption-desorption process. Adsorption thermodynamics and theoretical calculations revealed that C₃H₆ interacted more strongly with the framework than C₂H₄. The optimal cage size and oxygen-binding sites of MOF-808-For facilitated the selective trapping of C₃H₆ via multiple strong C-H···C and C-H···O hydrogen bonds, resulting in exceptional C₃H₆/C₂H₄ selectivity (11.1) and high C₂H₄ productivity (99.1 L·kg⁻¹ at 2 mL·min⁻¹ for 1:1 C₃H₆/C₂H₄ mixture) among reported MOFs. Furthermore, multi-cycle experiments demonstrated no significant loss in separation performance, confirming the excellent reusability of MOF-808-For for MTO product separation.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY COMMUNICATIONS
·
2024
·
IF 4.4
Kewei Wang,Yuhao Bai,Jie Tao,Weijie Hu,Long-Sheng Wang,Meng Zhang,Li-Ming Wu
The crystal size and uniformity of zeolites are crucial for their excellent performance in various industrial applications. Here, by utilizing commercial micrometer-sized zeolites as seeds and adjusting the weight percentage of seeds from 0 % to 5 %, the crystal sizes of silicoaluminophosphate SAPO-34 samples first decrease from 12.47 μm (S0) to 3.04 μm (S4), then increase to 5.34 μm (S5). Correspondingly, their relative crystal size deviations first decrease from 183.32 % to 60.53 %, then increase to 115.17 %, and the crystal size uniformity factors first increase from 0.33 to 1, then decrease to 0.53. The crystal size uniformity factor of sample S4 equals 1, indicating that it exhibits the best crystal size uniformity. This method is also applicable to aluminosilicate zeolites. By adjusting the weight percentage of seeds from 0 % to 3 %, the crystal sizes of ZSM-5 samples first decrease from 13.61 μm (Z0) to 2.49 μm (Z2), then increase to 4.46 μm (Z3); correspondingly, their crystal size uniformity factors first increase from 0.42 to 1, then decrease to 0.71. In addition, this route significantly enhances the yields and relative crystallinities of both SAPO-34 and ZSM-5 zeolites. Specifically, the yield and relative crystallinity of SAPO-34 zeolite increase by 40.71 % and 8.45 % respectively, while the yield and relative crystallinity of ZSM-5 zeolite improve by 24.05 % and 12.55 % individually. Notably, in the methanol to olefins (MTO) reaction, the propylene selectivity to butene selectivity ratio is inversely related to the crystal size; this suggests that crystal size may play a primary role in the formation of propylene and butene, with smaller crystal sizes being more favorable for the formation of propylene compared to butene. Furthermore, sample S4, which has a crystal size uniformity factor of 1 and a crystal size of 3.04 μm, exhibits excellent MTO performance; its catalytic lifetime increases by 69 %, and selectivity for ethylene plus propylene increases by 6.3 % in comparison to conventional sample S0.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
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
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Shipei He,Sheng Fan,Kai Yuan,Shujia Guo,Sen Wang,Zhangfeng Qin,Mei Dong,Weibin Fan,Jianguo Wang
Herein, K + was added in the synthesis gel to regulate the distribution of acid sites in the ITQ-13 zeolite and enhance its catalytic performance in the conversion of methanol to olefins (MTO). The results indicate that a proper content of K + ions in the synthesis gel can not only expedite the crystallization of ITQ-13 zeolite, but also significantly decrease the proportion of paired Al and distribute more Al atoms in the 10-ring sinusoidal channel out from the intersection cavity. Accordingly, over the H-ITQ-13(0.3 K) zeolite prepared using the synthesis gel with a KCl/Al 2 O 3 molar ratio of 0.3, the alkene cycle of MTO keeping to the dual cycle hydrocarbon pool (HCP) mechanism is preferably enhanced, whereas the hydride transfer and aromatization reactions are substantially suppressed. As a result, H-ITQ-13(0.3 K) exhibits much longer catalytic lifetime and higher selectivity to propene and butene , in comparison with the H-ITQ-13 counterpart obtained without adding K + .
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2024
·
IF 15.7
Kai Fan,Qinming Wu,Shuo Liu,Haiyu Kong,Sen Wang,Eduard Kunkes,Trees De Baerdemaeker,Andrei-Nicolae Parvulescu,Nils Bottke,Toshiyuki Yokoi,Dirk E. De Vos,Xiangju Meng,Weiping Zhang,Feng-Shou Xiao
Adjusting location and distribution of Al sites in the zeolite framework is critical for catalysis, and typical strategies include using zeolites as starting Al source. However, this approach is still challenging for aluminosilicate ITH zeolite. Herein, the distribution of Al species in the framework of ITH was efficiently regulated by implementing LTA zeolite as the aluminum source added in the starting gels (LTA-ITH). The obtained LTA-ITH zeolites have similar nanosheet morphology, textual parameters, and acidic properties to those of conventional ITH synthesized from boehmite (C-ITH), while the results of 27 Al MAS NMR spectra and 1-hexene cracking indicate that they have a different Al distribution. The use of LTA zeolite in starting gel is favorable for the formation of more Al species in sinusoidal and straight channels, compared with the C-ITH. Catalytic tests in the conversion of methanol to light olefin showed that LTA-ITH exhibited enhanced catalyst lifetime and propene selectivity compared with the C-ITH, which is reasonably attributed to the different locations of Al species in their respective ITH frameworks.
研究领域:
化学
·
催化科学
✓ 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）