AICHE JOURNAL
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2024
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IF 3.5
Liming Xia,Bofeng Zhang,Gang Hou,Shuo Zhang,Li Wang,Guozhu Liu
Structured catalysts exhibit the advantages of high diffusion efficiency and low heat transfer resistance, which have attracted increasing attention to non-adiabatic gas–solid process. However, the metal-supported coating catalysts face the problems of weaker bond strength and severe sintering, especially under the conditions of large flow rate and high temperature. Herein, metal@Silicalite-1 structured catalysts with high adhesion and thermal stability were successfully prepared by hydroxylating the substrate with anatase. Rich surface Ti-OH significantly strengthened the adhesion stability of the zeolite coating. In propane dehydrogenation reaction, the optimized PtZn@S-1-15Ti showed a high specific activity of 49.6 mol C3H6 ·mol Pt −1 ·s −1 with propylene selectivity above 99% at 600°C. The introduction of anatase accelerated the aggregation of silicon sources and induced nucleation with growth content of zeolite increased by 3.6 times. It breaks the inherent contradiction between high loading amount and strong binding ability of coated catalysts, which broadens the avenues for industrial applications.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
AICHE JOURNAL
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2024
·
IF 3.5
Liming Xia,Bofeng Zhang,Gang Hou,Li Wang,Sibao Liu,Guozhu Liu
Structured catalysts coatings exhibit excellent performance on non-adiabatic gas–solid process, deriving from their enhanced heat and mass transfer properties. However, the coating catalysts prepared by traditional hydrothermal method of zeolite encapsulating noble metal are prone to spalling, especially under conditions of large flow rate and high temperature. Herein, we prepared PtZn clusters encapsulated in silicalite-1 zeolite coating on stainless steel with high bonding strength by an improved in situ growth method. The optimized catalyst exhibited ultra-thin, uniform, continuous, and high degree of crosslinking, thereby enhancing mass transfer and thermal stability. In propane dehydrogenation reaction, the optimized PtZn@S-1-R showed a high specific activity of 14.7 mol C 3 H 6 $$ {\mathrm{mol}}_{{\mathrm{C}}_3{\mathrm{H}}_6} $$ mol Pt −1 s −1 and a propylene selectivity above 99% at 600°C with a high weight hourly space velocity of 120 h −1 . The metal-encapsulated zeolite coating catalysts broaden the application avenue for heterogeneous catalysis with great application prospects.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
Catalysts
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2020
·Vol. 10
·期 2
·211
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IF 3.52
Yongxin Zhang,Long Lin,Xiaoming Zheng,Chunyan Liu,Quanren Zhu,Hongchen Guo
In this study, a series of SnO2modified zeolite catalysts (Snx-S-1; x is the weight percentage of Sn) were prepared with SnCl2and a defective Silicalite-1 (S-1) zeolite via facile deposition–precipitation method. It was found that the stannic species modified all-silica zeolite catalysts were active for the intermolecular condensation of ethylenediamine (EDA) to 1, 2-Diazabicyclo [2, 2, 2] octane (TEDA) and piperazine (PIP). The best catalyst Sn6-S-1 (6 wt.% Sn loading) showed 86% EDA conversion and 93% total selectivity to TEDA and PIP. By contrast, the defective S-1 zeolite parent showed only approximately 9% EDA conversion under the same conditions. With the help of catalyst characterization techniques including hydroxyl vibration and pyridine adsorption FT-IR spectroscopy (transmission mode), the enhancement of the catalytic activity of the SnO2modified zeolite catalysts (Snx-S-1) was mainly attributed to the formation of mild Lewis acid sites in the siliceous zeolite. Both the hydroxyl nests of the defective S-1 zeolite and the dispersed SnO2clusters should be the important factors for the formation of mild Lewis acid sites on the modified zeolite. Based on the catalytic performance of the modified zeolite in the conversion of EDA to PIP and TEDA, it is inferred that the mildly acidified defective S-1 zeolite by the SnO2deposition modification might become a very active and durable catalyst for reactions involving strongly alkaline reactants and products.Keywords:defective Silicalite-1;SnO2modification;acidity;condensation of ethylenediamine
研究领域:
催化化学
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材料科学
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DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Fuyong Zhang,Wei Zhou,Xuewei Xiong,Yuhao Wang,Kang Cheng,Jincan Kang,Qinghong Zhang,Ye Wang
Catalytic transformation of CO2 into chemicals in large demand such as ethanol has attracted much research attention under the background of establishing carbon-neutral societies. Supported Rh catalysts are promising candidates for the hydrogenation of CO2 to ethanol but suffer from low ethanol productivity and poor catalyst stability. Here, we report that zeolite silicalite-1 embedded Na-promoted Rh nanoparticles (Na-Rh@S-1) demonstrate high productivity and stability for CO2 hydrogenation to ethanol. The ethanol selectivity of 24% was attained at a CO2 conversion of 10%, and the space-time yield of ethanol reached 72 mmol gRh–1 h–1, which outperformed most of the Rh-based catalysts reported to date. While a reference catalyst prepared by impregnation underwent deactivation, the Na-Rh@S-1 catalyst was stable for at least for 100 h owing to the confinement effect. The Na+ modifier played crucial roles in enhancing the CO2 conversion and ethanol selectivity by suppressing methane formation. The characterizations suggest that the presence of Na+ enables the coexistence of Rh0 and Rh+ and enhances CO2 adsorption, thus boosting ethanol formation. A comparative study between CO and CO2 hydrogenation reveals that the Na-Rh@S-1 catalyst is significantly more active and selective toward CO2 hydrogenation to ethanol.
研究领域:
催化化学
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环境科学
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材料科学
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DOI
高影响因子
CATALYSIS TODAY
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2024
·
IF 5.2
Ruiqi Wu,Ning Liu,Chengna Dai,Gangqiang Yu,Ruinian Xu,Biaohua Chen
The propane oxidation dehydrogenation assisted by CO 2 (CO 2 -ODHP) is currently a hot research topic, not only to meet growing demand of propylene but also to favor the CO 2 neutralization. In present work, a series of CrO x @S1-n-1.0 with different Cr contents (n= 2.2, 3.6 and 4.5 wt%) is synthesized based on a small gas molecule directing synthesis strategy, wherein the gaseous CO of 1.0 MPa was in situ introduced in the synthesis system to regulate the interaction and dispersion of CrO x over silicalite-1 (S1) support. The characterization results of XRD , XPS , H 2 -TPR, and Raman indicate that the CO can affect the oxidation state and dispersion of Cr species. As observed, the Cr species were highly dispersed over CrO x @S1–3.6 %-1.0 (in the form of Cr 6+ valance state), which however would aggregate to generate Cr 2 O 3 nanoparticles over the CrO x @S1–3.6 %-0 a prepared by impregnation method in absence of CO. The activity measurement indicates that the CrO x @S1–3.6 %-1.0 possesses the highest activity by displaying an average propane conversion of 50.4 % and CO 2 conversion of 23.6 % at 600 °C, which surpasses most of the literature reports. The CO 2 -ODHP reaction mechanism was further investigated by in situ DRIFTS , which indicates that dissociated H of propane can react with CO 2 to form formate (-COOH), in turn further reacts with H to produce byproducts CO and H 2 O, and the formate species can also react with the CrO 3 active site to form bicarbonate species (HCO - 3 ). Generally, present work has proposed a small gas molecule directing strategy to adjust the dispersions and chemical states of the loaded guest meals over catalytic support. The study of present work would contribute to other highly efficient catalyst design .
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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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Xingxing Cui,Hongyang Lyu,Yongming Chai,Bin Liu,Dongfeng Zhao,Chenguang Liu
The strong acidity on the external surface of ZSM-5 is a primary factor resulting in the low BTX selectivity and catalyst deactivation during the olefin aromatization. In this study, a membrane-restricted Silicalite-1@ZSM-5 core–shell structured catalytic catalyst was designed and constructed for 1-hexene aromatization using a hydrothermal coating method. TEM and NMR results confirmed the complete coverage of Silicalite-1 on the surface of ZSM-5, with a shell thickness of 50 nm. The further reaction of the TIPB (1,3,5-triisopropylbenzene) molecular probe reactions demonstrated the passivation of the acid sites on ZSM-5 external surface. The inert shell layer passivated the acid sites on the external surface, thereby suppressing the isomerization of PX and the side-chain alkylation reaction of light aromatics. Compared to ZSM-5, the Silicalite-1@ZSM-5 catalyst exhibited a 37.15 % increase in BTX selectivity, a 58.65 % increase in PX selectivity, significantly reduced coke deposition, and demonstrated better stability. This strategy of in-situ epitaxial growth of inert shell layers holds significant promise for enhancing the selectivity of shape-selective catalysts and extending catalyst lifetime.
研究领域:
催化化学
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材料科学
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石油化工
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DOI
高影响因子
AICHE JOURNAL
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2020
·Vol. 66
·期 5
·e16917
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IF 3.519
Bofeng Zhang,Yajie Tian,Dali Chen,Ling Li,Guozhu Li,Li Wang,Xiangwen Zhang,Guozhu Liu
Multimetallic nanocatalysts have attracted increasing attention for steam reforming owing to highly exposed active sites, but often suffering from severe sintering. Herein, we design subnanometric Ni-Pt bimetal clusters (ca. 1.7 nm) encapsulated in Silicalite-1 zeolite (2Ni0.5Pt@S-1) through ligand-stabilized method to prevent sintering by fixing the metal into microporous channels. In the steam reforming of n -dodecane test, 2Ni0.5Pt@S-1 gave an excellent activity and stability with a decrease of conversion only 4% at 600°C for 4 hr, which was about a quarter that of 2Ni0.5Pt/S-1 synthesized by co-impregnation method, ascribing to superior sinter-resistance of encapsulation structure. Moreover, 2Ni0.5Pt@S-1 exhibited a higher H 2 selectivity up to 69.9% than that of 2Ni0.5Pt/S-1 (64.4%), owing to suppressed methanation reaction based on subnanometric clusters. Shape-selective steam reforming of n -dodecane and ofm -xylene was also observed, because of m -xylene could hardly diffuse into the zeolite channels due to its bulky molecular size, further preventing potential deactivation by tars in reforming process.
研究领域:
催化化学
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材料科学
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能源化学
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DOI
高影响因子
CRYSTENGCOMM
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2019
·Vol. 22
·期 5
·945-954
·
IF 3.382
Lanjian Xu,Yangyang Yuan,Jie Zhang,Yanfei Zhang,Xiaomin Zhang,Lei Chen,Lei Xu
A green, cost-effective and facile steam-assisted crystallization (SAC) strategy was developed to synthesize core–shell-structured zeolite composites with different frameworks between the core and shell. Chemical incompatibility from different structures has been circumvented by dip-coating Silicalite-1 seeds and an in situ transformation process. Beta@Silicalite-1 zeolites with a nanoscale polycrystal Silicalite-1 shell wrapped around the monocrystal Beta core was synthesized. The crystallization process and synthetic parameters, such as the composition of the core, crystallization temperature and gel composition of the seed solution, were investigated. The results revealed the importance of stability of the core and the crystallization rate of the Silicalite-1 shell. Interestingly, a trace amount of aluminum in the core zeolite could help resist corrosion during crystallization. Further investigation on alkylation and etherification reactions over Beta@Silicalite-1 demonstrated the advantage in selectivity control toward self-etherification versus alkylation.
研究领域:
化学工程
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催化材料科学
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DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2018
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IF 3.468
Changsong Hu,Huiyan Zhang,Rui Xiao
In order to inhibit the coke formation on the external surface of HZSM-5 during catalytic fast pyrolysis (CFP) of biomass, core-shell structured HZSM-5@silicalite-1 zeolite catalysts were hydrothermally synthesized through the growth of silicalite-1 along the surface of a commercial HZSM-5. The catalyst characterization results indicate that silicalite-1 outer shell layer was successfully formed on the HZSM-5 core particles. Silicalite-1 coating was proved to be effective to reduce the external acidity as well as keep the internal acidity and channel patency of core HZSM-5 by catalytic probe reactions. The catalytic performances of HZSM-5@silicalite-1 samples in CFP of biomass were investigated using a bench-scale continuous feeding two-stage fluidized-bed/fixed-bed combination reactor. The results show that the productions of olefins and BTX were promoted (especially BTX), while the formations of catalyst coke and PAHs were significantly inhibited after silicalite-1 coating.
研究领域:
化学工程
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能源科学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
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IF 15.1
He Huang,Huahua Fan,Yuzhen Ge,Wanyue Ye,Yingcen Liu,Caicheng Song,Hua Lin,Xiaotong Zhang,Bing Li,Xiaowa Nie,Shufen Zhang,Rongwen Lu
The selective oxidation of the primary C H bonds in hydrocarbons to corresponding high-valued oxygenates is highly desired but challenging to realize. The difficulty arises from the high homolytic bond dissociation enthalpy of the C H bond, the relatively high reactivity of oxygenated intermediates, and the diversity of resultant products. Herein, we reported the in situ confinement of Au clusters in Silicalite-1 for the selective solvent-free oxidation of toluene to benzaldehyde. The doping of an alkali metal (K or Na) resulted in the formation of electron-rich Au species, which readily facilitate the activation of oxygen, In turn, toluene is activated by the produced reactive oxygen species in a single step, as confirmed through density functional theory (DFT) calculations. At optimal alkali metal doping, the selectivity to benzaldehyde could reach > 90 %, with the toluene conversion being 19.8 %. Remarkably, the total turnover number (TTN) of Au@Silicalite-1–0.2 K was found to be 29,658, which is one or two orders of magnitudes higher than the previously reported values. These findings are expected to inspire the design of highly efficient catalysts for the activation of fundamental feedstock with C H bonds.
研究领域:
催化
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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
SEPARATION AND PURIFICATION TECHNOLOGY
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2025
·
IF 9
Wei Chen,Pengfei Wang,Weike Jia,Huidan Zeng
Silicalite-1 zeolites/polymer composite membranes are among the most reliable materials for the pervaporation separation of m-X from xylene isomers. However, the separation factors of the present silicalite-1 zeolites/polymer composite membrane are low. This work has succeeded in fabricating dense and defect-free silicalite-1/PVA composite membrane for first improving the pervaporation separation performance of m-X/p-X isomers. The silicalite-1/PVA composite membrane was prepared by combining solution scraping and vacuum thermal crosslinking methods with fumaric acid as a crosslinker (denoted as silicalite-1/PVA-V). The silicalite-1/PVA-V composite membrane with a thickness of 15.3 μm, prepared with a fumaric acid/monomeric unit of PVA molar ratio of 0.05 after vacuum thermal crosslinking at 160 ℃ for 2 h, exhibited dense and defect-free structure with extremely low xylene swelling degree, good structural stability and mechanical properties as well as excellent pervaporation separation performance. Compared to the pure PVA membrane, the silicalite-1/PVA-V composite membrane exhibited better selective separation performance of m-X isomer. The temperature, amount of fumaric acid, crosslinking degree and membrane thickness significantly influenced the pervaporation separation performance. The optimum selective separation factor of m-X/p-X isomers and the corresponding total permeate flux were about 9.85 and 59.15 g·m −2 ·h −1 (60 ℃), respectively. The pervaporation experiments of long-time and repetitively prepared membrane demonstrated that the silicalite-1/PVA-V composite membrane had long-term structural stability and reproducibility. To demonstrate scalability, we showed that our strategy could produce large-size silicalite-1/PVA-V composite membrane with an area of 1000 cm 2 , which exhibited m-X separation performance similar to that of small membrane coupons. The present work provided a potentially scalable method for producing high-quality silicalite-1/PVA composite membrane for enhancing the pervaporation separation performance of m-X from xylene isomers.
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
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2024
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IF 8.1
Wenhua Feng,Ze Xiao,Binyi Chen,Yunhong Pi,Changsong Hu,Wenli Zhang,Qingwei Meng,Tiejun Wang
As non-noble metal catalyst, Cu-based catalyst shows promising applying potential in the aqueous-phase reforming of methanol (APRM) due to its high dehydrogenation activity and low CO selectivity, but the poor thermal and hydrothermal stability. Herein, a Cu@S-1 catalyst with ultrasmall-2nm Cu nanoparticles size was synthesized for the first time using one-step in-situ encapsulation strategy. By the confinement effect of the zeolite Silicalite-1 (S-1) micropores, the 1 wt%Cu@S-1 catalyst exhibited absolutely superior thermal stability without using any other promoter, as well as relatively good hydrothermal stability. After 600–700 °C high-temperature treatment, no obvious aggregation of the Cu nanoparticles was found, and superior performance in the steam reforming of methanol (SRM) was maintained after running for 36 h at 300 °C. In the APRM at 210 °C, the 1 wt%Cu@S-1 catalyst showed six-fold higher hydrogen releasing rate (4.26 × 10 5 μ mo l H 2 · g Cu − 1 · h − 1 ) than the impregnated 1 wt%Cu/S-1-im catalyst, meanwhile it exhibited even better performance than the commercial 5%Pd/C catalyst. Compared with the impregnated 1 wt%Cu/S-1-im catalyst, the confinement effect of the internal pores of the S-1 for the Cu nanoparticles in the 1 wt%Cu@S-1 catalyst effectively inhibited aggregation of the Cu particles and Cu leaching in APRM, thus greatly improved the activity and hydrothermal stability.
研究领域:
催化
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化学工程
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材料科学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）