DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 21
·7258-7266
·
IF 4.174
Guanqun Zhang,Yaqi Fan,Ju Huang,Lijin Wang,Chengguang Yang,Meng Lyu,Haiming Liu,Yanhang Ma
The increasing demands for catalysts with improved accessibility to reactants call for a rational synthesis of nanosized zeolites. Herein we developed a facile approach for highly crystalline MFI-type (Silicalite-1 and ZSM-5) and beta zeolites with variable Si/Al ratios and high yield. This was achieved by kinetically decoupling the nucleation from the growth process of the zeolites in a highly concentrated gel system via a temperature-staged treatment. The carefully controlled low-water environment ensures only nucleation in stage I (aging), and hence the generation of abundant nuclei for the subsequent rapid crystallization within a self-confined space at stage II (growth). The method, without using expensive templates or additives, allows the syntheses of nanosized, well-isolated ZSM-5 (Si/Al = 100–∞, 36–88 nm, yield >85%) and Beta (Si/Al = 25–100, 21–66 nm, yield >95%). The ultra-small crystal size endows ZSM-5 zeolites with good catalytic activity, product selectivity and remarkably longer lifetime in methanol conversion reactions.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Jinhao Du,Ruting Yuan,Feng Lin,Lijun Liao,Ge Yang,Furong Tao,Yuezhi Cui,Christine E.A. Kirschhock
Azonia-spiro compounds have been reported as organic templates for synthesizing many extra-large pore high silica zeolites , often isomorphically substituted by germanium . However, these templates are usually obtained in the presence of sodium hydroxide, leading to persisting sodium ions in the final products. Sodium cations may compete with azonia-spiro organics as templates during zeolite synthesis. Therefore, effect of any residual sodium cations on the synthesis results needs to be investigated. This work documents the effect of sodium ions on zeolite formation using four structurally similar azonia-spiro compounds as templates. Different silicogermanate zeolites (UTL, an unknown zeolitic phase, etc.) were formed in the absence of sodium cations. Notably, the syntheses of silicogermanate UTL and siliceous MTW zeolites using azonia-spiro[4,6] and [6,6] are reported for the first time. Controlled amounts of sodium chloride were added to zeolite crystallization mixtures without residual sodium hydroxide. In the presence of 0.005–0.1 mol/L Na + , silicogermanate zeolites were the dominant phases. Further increasing the Na + concentration to 0.152 and 0.317 mol/L, formation of UTL and an unknown silicogermanate phase were inhibited in favor of a dense sodiumgermanate (Na 4 Ge 9 O 20 ). Moreover, sodium ions next to azonia-spiro organic templates also influence the morphologies of the MTW zeolites. The observed high sensitivity of zeolite formation in the presence of even traces of sodium therefore has impact on synthesis protocols of large pore silicogermanate zeolites. This work highlights how small, often overlooked, factors in inorganic material synthesis can drastically change the outcome.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2018
·Vol. 8
·期 17
·4338-4348
·
IF 5.365
Xiaoli Yang,Xiong Su,Binglian Liang,Yaru Zhang,Hongmin Duan,Junguo Ma,Yanqiang Huang,Tao Zhang
The oxide–zeolite process has been attracting widespread attention due to its promising performance in syngas conversion to hydrocarbons with high selectivity and stability. Here, a composite catalyst containing Zn–Cr oxide and ZSM-5 zeolite provides a competitive option in the one-step conversion of syngas into C5+ hydrocarbons. In order to figure out the influence of the pore structure and acidity of zeolite on the oxide–zeolite process, alkali treatments on ZSM-5 are carried out. The treated ZSM-5 shows increased selectivity for gasoline fractions. With a set of structural and morphological characterization techniques, the formation of a hierarchical porous structure is demonstrated, which is favorable for the diffusion of heavy products. Furthermore, an increase in the number of Lewis acid sites, acting as the main active sites for the polymerization, cyclization and aromatization reactions, also contributes to the promotion of C5+ hydrocarbon production. It must be noted, however, that a certain amount of Brønsted acid sites is necessary for the tandem transformation of CH3OCH3 intermediates, which may further affect the CO conversion.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Wenjin Xu,Guangxu Zhang,Hanwei Chen,Guomeng Zhang,Yang Han,Yichuan Chang,Peng Gong
Two series of Mn/beta and Mn/ZSM-5 catalysts were prepared to study the influence of how different Mn precursors, introduced to the respective parent zeolites by wet impregnation, affected the selective catalytic reduction (SCR) of NO by NH 3 across a low reaction temperature window of 50–350 °C. In this study, the catalysts were characterized using N 2 adsorption/desorption, X-ray diffraction, X-ray fluorescence, H 2 temperature-programmed reduction, NH 3 temperature-programmed desorption and X-ray photoelectron spectroscopy. As the manganese chloride precursor only partially decomposed this primarily resulted in the formation of MnCl 2 in addition to the presence of low levels of crystalline Mn 3 O 4 , which resulted in poor catalytic performance. However, the manganese nitrate precursor formed crystalline MnO 2 as the major phase in addition to a minor presence of unconverted Mn-nitrate. Furthermore, manganese acetate resulted principally in a mixture of amorphous Mn 2 O 3 and MnO 2 , and crystalline Mn 3 O 4 . From all the catalysts screened, the test performance data showed Mn/beta-Ac to exhibit the highest NO conversion (97.5%) at 240 °C, which remained >90% across a temperature window of 220–350 °C. The excellent catalytic performance was ascribed to the enrichment of highly dispersed MnO x (Mn 2 O 3 and MnO 2 ) species that act as the active phase in the NH 3 -SCR process. Furthermore, together with a suitable amount of weakly acidic centers, higher concentration of surface manganese and a greater presence of surface labile oxygen groups, SCR performance was collectively enhanced at low temperature.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 7
·3653-3660
·
IF 3.049
Guang Xiong,Miaomiao Feng,Jiaxu Liu,Qingrun Meng,Liping Liu,Hongchen Guo
An aerosol-assisted hydrothermal method has been applied to synthesizing hierarchical beta zeolites with SiO2/Al2O3 ratios ranging from 44 to 392 in NaF media. Two different morphologies, including nano-aggregates with interparticle mesopores and plate-like zeolites with intracrystalline mesopores, can be formed depending on the SiO2/Al2O3 ratios of the synthesis gels. A possible mechanism for the formation of the beta zeolites has been proposed. The obtained beta zeolites show hierarchical pores, good Al species distribution and less internal defect sites. Evaluation, by the cracking of 1,3,5-triisopropylbenzene (1,3,5-TIPB), is consistent with the acidic properties and the pore structure of beta zeolites with different ratios of SiO2/Al2O3.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Jun Liang,Yingying Wang,Xiangcheng Li,Ming Xu,Shaochun Shen,Chuang Liu,Wenhua Fu,Weichuan Tao,Zhiqing Yuan,Zhendong Wang,Weimin Yang
A novel quaternary ammonium hydroxide , p-Xylylene-bis(N-methylpiperidinium hydroxide) (XBMPOH), was prepared and used as an organic structure-directing agent (OSDA) for the syntheses of BEC zeolites . Both Si,Ge- BEC and Al incorporated BEC (Al- BEC ) zeolites were successfully synthesized. In comparison with commonly used OSDA (tetraethylammonium hydroxide (TEAOH)), XBMPOH was more suitable for the crystallization of BEC structure, especially in the Al containing system. Al- BEC zeolites were directly synthesized at lower germanium and OSDA content, in a wider (Si + Ge)/Al ratio range (20 to ∞ vs. 50 to ∞) and shorter time (6 h vs. 12 h). For the first time, Al- BEC zeolites were used as a solid acid to catalyze the alkylation of benzene with 1-dodecene, and showed significant catalytic performance. After an acidic treatment procedure, the catalytic performance was further improved due to the removal of non-framework Al with accompanied exposure of framework Al.
研究领域:
化学工程
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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
LUMINESCENCE
·
2025
·Vol. 40
·期 5
·e70177
·
IF 3
Ruihao Huang,Song Ye,Meiyan Wang,Ling Pan,Tianning Zheng,Deping Wang
The manipulation of silver nanoclusters' luminescence performance in heteroatom zeolite was rarely reported. In this research, the heteroatom Ga-FAU zeolites were synthesized together with the Al FAU zeolite, based on which a series of Ag nanoclusters loaded Al FAUAg and mGa FAUAg zeolites were prepared. The spectroscopy characterization indicated that emission intensity of silver nanoclusters is greatly enhanced in Ga-containing zeolites compared to that in Al FAUAg, and meanwhile, the excitation and emission peak showed redshift and blueshift, respectively, with the introduction and increasing proportion of Ga atoms in mGa FAUAg. The TD-DFT method was carried out on the [Ag 3 Ga x D6r] + (x = 0, 1, 2, 3, 4, 5) clusters to study the effect of framework Ga on the luminescence properties of Ag 3 + in the D6r cavity of FAU zeolite, which suggested that the S 1 → S 0 transition of Ag 3 + is responsible for the radiative visible emission. Moreover, the low-energy shift for S 3 → S 0 transition and high-energy shift for S 1 → S 0 transition were observed with increasing x value in [Ag 3 Ga x D6r] + clusters, which is in accordance with the experimental observation. This research provided an alternative method for the manipulation of silver nanoclusters' luminescence performance by using heteroatom zeolite, which contributed to the design of solid phosphors with desirable emission.
研究领域:
材料科学
·
光化学
·
计算化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 19
·9076-9080
·
IF 8.867
Xin Xiong,Dingzhong Yuan,Qinming Wu,Fang Chen,Xiangju Meng,Ruihua Lv,Daniel Dai,Stefan Maurer,Robert McGuire,Mathias Feyen,Ulrich Müller,Weiping Zhang,Toshiyuki Yokoi,Xinhe Bao,Hermann Gies,Bernd Marler,Dirk E. De Vos,Ute Kolb,Ahmad Moini,Feng-Shou Xiao
High silica CHA zeolite plays an important role in selective catalytic reduction of NOx with NH3 (NH3-SCR), but its synthesis is not highly efficient due to the use of a relatively high-cost structural directing agent (SDA) N,N,N-trimethyl-adamantammonium hydroxide (TMAdaOH) and relatively long crystallization time under hydrothermal conditions. Herein, we report an efficient and rapid synthesis of a high silica CHA zeolite possessing good crystallinity and uniform crystals (CHA-ST). The method includes interzeolite transformation of high silica FAU zeolite in the absence of water but the presence of zeolite seeds and a bromide form of the SDA. The absence of water in the synthesis significantly improves the zeolite yield by avoiding dissolution of aluminosilicate species in aqueous media, while the addition of zeolite seeds remarkably enhances the crystallization rate under solvent-free conditions. In addition, this route allows the use of a low-cost bromide form of the SDA. Catalytic tests in the NH3-SCR show that copper-exchanged CHA-ST (Cu-CHA-ST) exhibits comparable catalytic properties to those of Cu-SSZ-13 obtained from the conventional hydrothermal route.
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 Environmental Chemical Engineering
·
2025
·
IF 7.2
Yunhe Li,Xiubo Min,Yilin Wei,Peiyuan Liang,Yixuan Yu,Tianjun Sun
Zeolite-based catalysts are extensively investigated for industrial applications due to their unique pore structure, remarkable thermal/hydrothermal stability, and abundant acid sites. However, the inherent lack of active sites for oxygen activation in non-reducible supports leads to suboptimal low-temperature oxidation activity. This study synthesized SSZ-39 (AEI-type) zeolite via interzeolite transformation from Y (FAU-type) zeolite, exploring the effects of gel composition on its structural properties and the influence of different cerium precursor salts on the CO oxidation performance of platinum-loaded zeolite catalysts. The results show that introducing seed crystals can replace 40 % of the organic structure-directing agent, leading to the synthesis of pure SSZ-39 zeolite with a specific surface area of 588 m 2 /g, where aluminum species are solely present as framework aluminum. The Pt-8Ce(ca)/SSZ-39 catalyst, prepared using cerium acetate as the precursor, demonstrates excellent low-temperature activity and stability, achieving 100 % CO conversion at 150 °C and maintaining it for over 100 h. After hydrothermal aging at 750 °C, the conversion temperature increased by only 20 °C, with the outstanding hydrothermal stability attributed to the stable framework structure of SSZ-39 zeolite. The highly dispersed Pt-CeO 2 interface increases surface-active oxygen species, which induce the transition from the L-H to the MvK reaction mechanism. This reduces competitive adsorption between O 2 and CO, and the oxygen vacancies formed during the reaction serve as additional O 2 activation sites, addressing the low-temperature CO oxidation issue in non-reducible support zeolite-based catalysts.
研究领域:
催化
·
材料科学
·
化学工程
·
环境科学
·
无机化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Shuo Li,Jiahe Sun,Songcheng Bo,Fangfang Yang,Kaixuan Yang,Ting Su,Hongying Lü,Zhiguo Zhu
Oxidative desulfurization (ODS) is regarded as a viable carbon–neutral way to produce sulfur-free fuels. Mo framework substituted zeolite is considered to be a potential heterogeneous catalyst to achieve this goal. Nonetheless, the hydrothermal synthesis of Mo-containing zeolite remains a challenging task in terms of theses aspects including the difficulty in isomorphous substitution of Si with Mo due to the large ionic radius of Mo (59 pm), the tendency of Mo species to precipitate in the alkaline medium, and the prolonged crystallization time. Herein, Mo-Beta zeolites were synthesized via interzeolite transformation within a short time of 24 h. The crystallization process followed the dissolution–recrystallization mechanism. Various techniques were used to confirm that Mo species was isomorphously substituted into zeolite framework. Mesopore was also created over Mo-Beta zeolite with different Mo contents. This Mo-Beta zeolites were employed as heterogeneous catalysts in oxidative desulfurization, where framework Mo species was found to be the catalytic active sites. The process parameters (catalyst dosage, reaction temperature, and H 2 O 2 amounts), reaction kinetics, and reusability were also investigated. Mo-Beta exhibited remarkably high catalyst-weight-based space–time-yield and active-site-based turnover frequency, surpassing the zeolite catalysts in the literatures. This work paves an avenue to the hydrothermal synthesis of metallosilicate zeolites for catalytic oxidations.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2025
·
IF 4.7
Xingyang Li,Dandan Zhang,Quanwei Zheng,Jiakui Chang,Xuan Liu,Renchun Yang,Meng Pan
In industry, it is highly desired to prepare Al-rich hierarchical zeolites by conventional alkali treatment without the use of costly chemical and special process. Here we provide an alternative strategy in which crystal defects are employed as mesopore directing agents. The effective elimination of the intracrystalline defects induces the generation of mesoporous structure in the alkali treatment process. Thus, the limitation originating from the framework Si/Al ratio of parent zeolite is circumvented. This strategy holds all merits of the conventional alkali treatment approach, which is industrially unfavorable. As an example, the Al-rich hierarchical ZSM-5 zeolites with very low Si/Al ratios were successfully prepared. The obtained Al-rich hierarchical zeolites were characterized by XRD, XRF, SEM, TEM, N 2 adsorption-desorption, in-situ IR, MAS NMR and NH 3 -TPD. The results showed that Si/Al ratios of the prepared hierarchical ZSM-5 zeolites were around 10 and the increases of external surface area and mesoporous volume were up to 2.6 and 3.7 times respectively in comparison with parent zeolite. Moreover, the constructed mesopores were interconnected open channels. In the catalytic cracking of 1,3,5-triisopropylbenzene, the Al-rich hierarchical ZSM-5 zeolites exhibited an excellent performance because of the improved diffusion of reactant and product.
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 COMMUNICATIONS
·
2023
·
IF 3.7
Li Guo,Jialing Chen,Shaokang He,Tingyu Liang,Lijun Lu,Shenke Zheng,Xinyue Hu,Lan Yi,Xiaoqin Wu
The [Fe, Al]-FER zeolites, which are prepared from the interzeolite conversion method (from MWW to FER topology) with high Al and Fe content (Si/Al of 8–18 and Si/Fe of 11–13), exhibit excellent catalytic performances and hydrothermal tolerance for NH 3 -SCR reaction. The interzeolite conversion process can be tuned by optimizing the zeolite synthesis conditions such as synthesis gel composition, crystallization time, crystallization temperature, and adding MWW seeds. The work can provide a new strategy to synthesize high Al and Fe content zeolite with high hydrothermal stability for NO x removal.
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
危险品化学品经营许可证（带存储）