CATALYSIS TODAY
·
2022
·
IF 6.562
Wen Liu,Pengfei Wei,Junjie Li,Yanan Wang,Shirui Xu,Zhiqiang Yang,Xuebin Liu,Longya Xu,Xiujie Li,Xiangxue Zhu
The morphology control of zeolite has attracted extensive attention because of its close relationship with catalytic performance. How to control the crystal morphology of EUO zeolite on premise of low silica to alumina ratio is a challenging task. This study provides a novel route for controlling the morphology of Al-rich EUO zeolite via inter-zeolite transformation from Si-rich *MRE zeolite within 24 h. The morphology change from nanocrystals to coffin-like single crystal exhibits the merits of inter-zeolite transformation strategy in morphology control. Characterization tracking reveals that the deposition of aluminum species on parent *MRE zeolite is not uniform and migration between different precursors happens during the crystallization. No obvious mass transfer is observed between the liquid and solids after 2 h indicating it may follow a solid phase crystallization mechanism. Compared with conventional EUO samples, the EUO zeolite obtained by inter-zeolite transformation exhibits higher p-xylene selectivity. This approach not only provides a novel morphology control strategy for Al-rich EUO zeolite, but also promotes the understanding of the zeolite crystallization through inter-zeolite transformation route.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Particuology
·
2017
·
IF 2.621
Rongjie Ling,Wu Chen,Jin Hou
Modified nanosized MFI (ZSM-5 and silicalite-1) zeolites were successfully synthesized by a hydrothermal method using aluminum isopropoxide and tetraethylorthosilicate as the raw materials. The synthetic zeolites were characterized by X-ray diffraction, energy dispersion spectroscopy, and scanning electron microscopy. The ZSM-5 and silicalite-1 zeolites exhibited ellipse-like and cubic columns, respectively. The K + ion-exchange equilibrium and ion-exchange capacity of the synthetic zeolites in seawater were investigated. The K + ion-exchange of synthetic zeolites was rapid and reached an ion-exchange balance in approximately 20 min. The K + ion-exchange capacity of ZSM-5 and silicalite-1 in seawater was 56.7 and 48.7 mg/g, respectively. The synthetic zeolites have high selectivity toward K + , and therefore, they can be used to selectively extract potassium from seawater.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
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
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Yichuan Li,Guofu Zhu,Yu Wang,Yongming Chai,Chenguang Liu,Shengbao He
Oriented molecular sieve membranes prepared on the surface of a specifically shaped substrate have been applied in the separation and catalysis process, but there is no report on the directional growth of molecular sieve membranes on the surface of spherical substrates. Here, a simple in situ crystallization method was employed to successfully prepare a single layer of b-oriented continuous titanium silicalite-1 (TS-1) molecular sieve membrane on the surface of 2-mm alumina beads. First, a titania intermediate layer was loaded on the surface of beads by the dipping method, and the surface was then modified with the TBOT modification solution. The ratio of the precursor solution was n(TEOS):n(TBOT):n(TPAOH):n(H 2 O) = 1:0.010:0.15:40 and was crystallized at 180 °C for 72 h to prepare the membrane. The content of the templating agent and water affected the size of TS-1 crystal grains and membrane crosslinking—both in turn influenced the continuity and orientation of the molecular sieve membrane. Spherical membrane catalyst was applied to catalyze the epoxidation of chloropropene in a fixed bed reactor, and the conversion of hydrogen peroxide and selectivity of epichlorohydrin attained 87.4% and 93.2%, respectively. This work provides a foundation for the design of novel TS-1 immobilized catalyst.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Han Li,Qile Zhao,Huan Zhang,Jinfang Wu,Zexu Zhang,Yue Yin,Wenbo Wang,Fang Guo
Adsorption techniques are crucial for removing high and trace levels of heavy metal pollutants from water, enabling effective pollution control without causing secondary contamination. Achieving “all-rounder” adsorbents with high capacity, efficiency, speed, and cost-effectiveness is challenging. Materials with structural defects, firm surface charges, and porous structures are ideal for rapid and efficient mass transfer. Herein, using a “homologous transformation” strategy, we converted abundant kaolin into 4A and Na-P1 zeolites-based porous silicate adsorbents with enhanced surface active sites and optimized adsorption pathways. Site energy analysis confirmed that these upgraded structures have high-density, high-energy adsorption sites, facilitating rapid Pb(II) removal from water. These zeolite-based adsorbents exhibit exceptional Pb(II) adsorption capacities (416.60 mg/g for 4A and 400.21 mg/g for Na-P1) and ultra-fast initial rate constants (409.84 and 617.28, which are 174.62 and 263.01 times greater than those of kaolinite; and 56.56 and 85.19 times greater than those of commercial activated carbon, respectively). DFT calculations verified strong adsorption forces for Pb(II) (adsorption energy: −0.52 eV). Removal efficiencies reached 99.75 % for 4A and 99.96 % for Na-P1 zeolite-based adsorbents, ensuring treated water is safe and supports seed germination and plant root growth. These adsorbents also perform well in the presence of interfering ions like Zn(II), Cu(II), Cd(II), and Ni(II). After 10 regeneration cycles, they retain over 73 % of their original capacity, demonstrating an optimal balance among capacity, speed, efficiency, and interference resistance, aligning with sustainable development principles of “from nature, for nature”.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2025
·
IF 3.2
Zhu Mengxuan,Liu Yifan,Ma Jiaxin,Wang Longyang,Wang Rui,Jiang Heng,Jin Changzi
Developing the novel green routes for synthesis of important aluminosilicate zeolites is of significant for theoretical research and practical application. In this work, MCM-22 zeolite with MWW-topology was synthesized through seed-assisted interzeolite transformation from FAU zeolite without using additional organic template. The key influence factor to the synthesis process was investigated and the zeolite products were characterized by a series of modern techniques. It has been shown that not only the presence of MCM-22 seed, but also the appropriate SiO 2 /Al 2 O 3 and Na 2 O/SiO 2 molar ratio of starting synthesis gel with were crucial to synthesize pure MWW zeolite. The hexamethyleneimine template occluded in seed also played a key role in successful interzeolite transformation, but did not participate structure-directing of MWW product. Although the zeolite synthesized by interzeolite transformation showed lower surface area and pore volume compared with MCM-22 zeolite prepared by conventional route, the Pt modified sample exhibited promising catalytic performance in hydroisomerization of n -heptane. Graphical
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
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Meng Pan,Jiajun Zheng,Yujian Liu,Weiwei Ning,Huiping Tian,Ruifeng Li
The conversion of the heavy fractions of crude oil into transportation fuels and chemical feedstocks is still a severe challenge for fluid catalytic cracking (FCC) technology, in which geometrical parameters of the catalyst are of key importance to the accessibility for reactant and product molecules to travel through the pore space. Here a new core-shell zeolite catalyst with hierarchical pore network from macro- via meso- to micropores is developed by controlling overgrowth of another zeolite shell on the surface of a commercial Y-zeolite. The zeolite shell is a distinctive nano ZSM-5 crystals. The core-shell zeolite catalyst has a high thermal and hydrothermal stability because of high crystallinity, which can meet the industrial requirements. More importantly, the heavy oil can be cracked by the designed zeolite catalyst step-by-step into the required products. The meso- and macroporous shell facilitates pre-cracking the large molecules in heavy oil into moderate ones which can directly diffuse into the micropores of the Y-zeolite to be cracked selectively into the desired products. Both the pore structure network and acid sites distribution of the core-shell zeolite catalyst in the FCC processing are completely harmonious. As a practical example, the catalytic cracking of VGO heavy oil is actualized over the new catalyst. The results showed that the conversion of heavy oil and the yield of gasoline increased by 1.8 wt% and 8.9 wt% respectively, LPG decreased by 6.9 wt%, iso -paraffins and olefins in gasoline fraction increased by 5.21 wt% and 6.31 wt% respectively, aromatics decreased by 11.55 wt%, because of the graduated cracking in core-shell zeolite and returned isomerization in nano ZSM-5, compared with commercially industrial FCC catalyst.
研究领域:
化学工程
·
催化材料
·
石油加工
✓ 已验证
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Zongyang Zhang,Yuping Li,Ze Chen,Fuchao Ji,Xiaohong Liang,Haicheng Xuan,Lina Han,Peide Han
Developing an economical and high-efficiency synthesis pathway of SSZ-13 zeolite is of great significance for the ammonia selective catalytic reduction of nitrogen oxides (NH 3 -SCR of NO x ) reactions. Herein, SSZ-13 zeolite were synthesized using L zeolite as the aluminum source in the presence of a mixed structure directing agent (SDA) composed of N,N,N, trimethtyl-1-adamantammonium hydroxide (TMAdaOH) and tetraethylammonium hydroxide (TEAOH). This synthesis strategy aims to accelerate the crystallization rate through interzeolite transformation, while less expensive TEAOH can play a cooperative structure-directing role, thus reducing the consumption of expensive TMAdaOH template. The results showed that pure SSZ-13 zeolites with high crystallinity can be obtained from L zeolite within 12 h at 160 ℃ under low TMAdaOH/SiO 2 ratio of 0.05 (too low to carry out the synthesis on its own in the current synthesis system) in the presence of TEAOH. Moreover, the crystallization mechanism was also investigated by XRD, FT-IR, SEM and TG-DTG techniques. It was proposed that the crystallization of SSZ-13 occurs through the formation of SSZ-13 nuclei under the direction of TMAdaOH and promotion of TEAOH, subsequently TMAdaOH was incorporated in the framework to further induce the crystal growth of SSZ-13. Especially, the zeolite crystal size can be modulated by the amount of TEAOH added. In addition, After Cu 2+ exchange, the obtained Cu-SSZ-13 sample exhibits superior catalysis performance in the NH 3 -SCR of NO x reaction, and the NO x conversion rate remained over 90 % across a broad range from 200 to 600 °C, demonstrating its significant application potentials in NO x removal from diesel vehicle exhausts.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Lingling Zou,Meihua Zhu,Xinpeng Li,Yin Yang,Qi Zhou,Wenjun Yuan,Na Hu,Xiangshu Chen,Hidetoshi Kita
Construction of hierarchical pore structure in supported titanium silicalites was an effective strategy to enhance catalytic performance and avoid the separation process in industrial applications. Herein, the hierarchical TS-2 zeolites were successfully prepared on the TiO2-modified α-Al2O3 pellets by “bottom-up” method, which had good and stable catalytic performance for the allyl chloride epoxidation. TritonX-100 could construct a mesopore structure, restrain nucleation, and affect titanium coordination of the zeolites, which was beneficial for preparing large size, much hexa-coordination titanium content, and hierarchically supported TS-2 zeolites in this work. Besides, the TiO2-modified layer greatly increased the density and surface reactivity of hydroxyl groups on the α-Al2O3 pellet, which were well-situated to prepare homogeneous and anatase-free hierarchical TS-2 zeolite layers. The hierarchically supported TS-2 zeolites were applied to the epoxidation of allyl chloride with hydrogen peroxide, and allyl chloride conversion and epichlorohydrin selectivity were up to 99.13% and 96.53%, respectively.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Xu Zhang,Yaquan Wang,Xiao Wang,Hengbao Chen,Hongyao Li,Chao Sun,Liying Sun,Chunyang Fan,Cui Wang
In this study, an efficient route was developed to prepare high quality erionite (ERI) zeolite by hydrothermal conversion of faujasite (FAU) zeolite as an aluminosilicate source in the presence of N,N -dimethylpiperidinium hydroxide (DMPOH). Pure ERI zeolite was successfully synthesized within only 8 h by carefully controlling the alkalinity (OH − /SiO 2 ) of the initial gel and the proportion of DMP + and K + . Compared with the conventional ERI zeolite synthesized via a Charge Density Mismatch method, the FAU-derived ERI zeolites show superior properties such as higher crystallinity , smaller crystal size, larger micropore volume and better hydrothermal stability. In addition, catalytic test in the ethanol dehydration reaction shows that the ERI zeolites obtained from FAU exhibit extraordinary performances to those of the conventional one. Finally, crystallization process from FAU to ERI was investigated in detail by UV Raman and XRD . The results show that the framework of ERI zeolite is formed by rearrangement of 4-rings generated from the initial FAU zeolite.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Mingwei Cai,Jiongcai Chen,Heng Liu,Luxin Sun,Jiahao Wu,Tingting Cui,Shiyang Zhang,Xiaohua Ma,Yonggang Min
One of the main issues with membrane-based gas separation lies in the unexplored relationship between the precursors and their derived carbon molecular sieve membranes (CMSMs). Herein, we designed a series of TR polymers with gradient PBO content as precursors to investigate the carbonization mechanisms of PBO structure. The process of transforming the polymer precursor into carbon structure throughout pyrolysis involves utilizing an array of characterization techniques along with pyrolysis simulation. Results indicated that a higher PBO content leads to stronger molecular sieving effect of the resulting CMSM. The TR-CMS-50 membrane demonstrated exceptional gas separation performance with high permeability (P H2 = 3154 and P CO2 = 1495 Barrer) as well as ultra-high H 2 /CH 4 (384) and CO 2 /CH 4 (166) selectivity, which far exceeded the newest Upper bound line, showing significant potential for practical applications. This may can be attributed to “delayed effect” of the PBO structure which requires pyrolysis at higher temperatures, leading to more intense pyrolysis and the release of nitrogen-containing substances. Meanwhile, PBO has a cyclic system with a strong aromatic structure that closely resembles a carbon strand, which probably facilitates aromatization and enables it to more easily integrate into CMS structure, resulting in a more orderly arrangement in the Langmuir phase and generating higher concentration of pyrrolic-N (58.7 % vs. 44.1 %) as well as graphitic-N (31.6 % vs. 17.2 %). Thus, increasing the PBO content makes the derived CMS denser and significantly enhances its molecular sieving capacity. This study offers new insights into the development of precursor structures that creates high-performance CMSMs.
研究领域:
材料科学
·
化学工程
·
膜技术
✓ 已验证
产品关联
DOI
高影响因子
Processes
·
2023
·Vol. 11
·期 4
·1075
·
IF 3.5
Zhaochen Huang,Guoqiang Huang
Usually, the ion implantation gases used in semiconductor production are required to be extremely high in purity. Due to the presence of trace CO2in electronic special gas BF3, the quality of the material is significantly affected, which makes it crucial to impose control on CO2content. Unlike a series of blank adsorbents reported in other studies, the zinc-loaded adsorbents prepared in this study are intended for the adsorption of CO2from CO2/BF3. Firstly, the materials were characterized by XRD, BET, SEM-EDS and TG-DSC analysis, etc., and the breakthrough curves of the adsorbents as obtained under different preparation conditions were investigated at 20 °C and 200 kPa. The results show that the adsorption performance reached the optimal level when the activation temperature was 450 °C and a 13X molecular sieve was impregnated by 0.15 mol/L Zn(NO3)2. Moreover, compared with the Zn-13X, the breakthrough time was reduced to 69% and 44% in two adsorption cycles, respectively. Finally, FTIR was used to reveal the adsorption mechanism of the carbonates produced by CO2adsorption. It was found that the adsorption performance was affected by the irreversible reduction in the number of active sites due to the continuous formation of polydentate carbonate during adsorption and regeneration.Keywords:CO2adsorption;13X molecular sieve;carbonate species
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
危险品化学品经营许可证（带存储）