CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Qiuxia Zou,Hongshen He,Jie Xie,Shibo Han,Weijie Lin,Ajoy Kanti Mondal,Fang Huang
In this study, Sn modified molecular sieves with Lewis (L) acid center and Al modified molecular sieves with Brönsted (B) acid center were prepared by post-synthesis method. They were applied to the catalytic pyrolysis of Kraft lignin for the preparation of bio-oil. The acid properties of acid modified zeolites were systematically investigated by XRD, SEM, EDS and Py-FT-IR, and the bio-oil is analyzed by heteronuclear single quantum coherent nuclear magnetic resonance (HSQC-NMR). By separating L acid and B acid from zeolite molecular sieves, the conformational relationships between these two acids on the oxygen-containing functional groups in Kraft lignin bio-oil are investigated separately. The results show that acid modified molecular sieves’ L acid and B acid can effectively improve the cleavage of aromatic C-O bonds including methoxy and ether bonds. The L acid of Sn modified molecular sieve tends to break the O-C 4 bond and the natural methoxy bond, while the B acid of Al modified molecular sieve generates aliphatic hydrocarbon intermediates and phenolic compounds by breaking the C β -O bond and rearranging the methoxy bond. By chemical characterization of the acid modified molecular sieves and the bio-oil, the conformational relationship between the L acid and B acid of zeolite molecular sieves on the deoxygenation efficiency of Kraft lignin pyrolysis bio-oil is established.
研究领域:
化学工程
·
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 105
·86620-86624
·
IF 3.84
Tao Wang,Huiping Zhang,Ying Yan
A novel porous zeolite beta coating/PSSF composite was prepared by secondary growth method in fluoride media. The morphology of zeolite beta coating/PSSF composite was characterized by SEM and the structural and textual properties of composite were characterized by XRD and N2 adsorption/desorption isotherms on ASAP 2020, respectively. The thermal stability of composite was analyzed by thermogravimetry (TG) and differential scanning calorimetry (DSC). The results indicated that well-intergrown and continuous zeolite beta coating with highly crystallinity were successfully synthesized on the surface of paper-like stainless steel fibers support. The structures of zeolite beta coating/PSSF composite were three-dimensional network with large void volume and majority of microporous structure. The thickness of zeolite beta coating on stainless steel fibers is approximate 2 μm. The specific surface area (SBET) and the total pore volume of composite were 118 m2 g−1 and 0.067 cm3 g−1, respectively. The composite was stable at temperature up to 650 °C.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Baoyu Wang,Ximing Yan,Xingyuan Zhang,Haiyan Zhang,Faping Li
Beta zeolite exhibits satisfactory catalytic activity in the synthesis of polyoxymethylene dimethyl ethers. However, the microporous channels of beta zeolite have adverse effects on mass transfer of macromolecules. In this work, it was found that the textural and acidic properties of catalysts could be improved by citric acid treatment. Extensive characterization confirmed that citric acid induced significant pore-expanding on catalysts, and its dealumination and realumination effect could lead to reduced amount of total acid sites and increased amount of Brønsted acid sites (BAS). Meanwhile, a good positive correlation was found between amount of external weak BAS and initial reaction rate. It was speculated that BAS with relatively weak acid strength might be the primary active sites in this reaction. Compared with the blank sample, the initial reaction rate of optimal catalyst was increased by 100 %, and the conversion of trioxane was increased by 86.5 %, indicating a significantly improved catalytic activity.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 56
·34187-34196
·
IF 3.119
Yuan Yuan,Jianwen Wei,Linlin Geng,Dejun Mei,Lei Liao
An amine-bifunctionalized composite strategy was used to fabricate grafted-impregnated micro-/mesoporous composites for carbon dioxide capture. The micro-/mesoporous Beta/KIT-6 (BK) composite containing a high-silica zeolite with a three-dimensional twelve-membered ring crossing channel system and cubic structural silica was used as a support, and 3-aminopropyltrimethoxysilane (APTS) and tetraethylenepentamine (TEPA) were used as the grafted and impregnated components, respectively. The amine efficiency, adsorption kinetics, thermal stability, regeneration performance, and the effects of impregnated amine loadings (30–60%) and temperatures (40–90 °C) on the CO2 adsorption performance were investigated using a thermal gravimetric analyzer (TGA) in the mixed gases (15 vol% CO2 and 85 vol% N2). At 60 °C, the bifunctionalized Beta/KIT-6 (1 mL APTS g−1 BK) displayed the highest CO2 adsorption capacity of 5.12 mmol g−1 at a TEPA loading of 50%. The kinetic model fitting results showed that the CO2 adsorption process was a combination of physical and chemical adsorption, wherein the chemical adsorption is dominant. After five adsorption/desorption cycle regenerations, the saturated adsorption capacity of the composite material was 4.86 mmol g−1, which was only 5.1% lower than the original adsorption capacity. The composites demonstrated excellent CO2 adsorption performance, indicating the promising future of these adsorbents for CO2 capture from actual flue gas after desulfurization.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2024
·Vol. 14
·期 4
·248
·
IF 3.8
Xinyi Xing,Wanni Liu,Siquan Xu,Jianxiu Hao
H-Beta zeolite is a solid acid catalyst commonly utilized in the catalytic conversion of biomass resources. In this study, H-Beta zeolite was calcined at different temperatures (350, 550, 750, and 1000 °C) to explore the effects of high temperature-induced dealumination on its physicochemical properties and its catalytic ability to convert glucose into 5-hydroxymethylfurfural (HMF). It was shown that as the calcination temperature increased, the Si-O-Al bond of H-Beta zeolite was broken and its dealumination effect was enhanced. Dealumination led to the collapse of the framework of H-Beta zeolite and a reduction in the number of acid sites, which in turn reduced its catalytic performance and the efficiency of HMF formation from glucose. Furthermore, H-Beta zeolite exhibited an extraordinary catalytic ability for the production of HMF from carbohydrates. Using glucose and cellulose as substrates, superior HMF yields of 91% and 46%, respectively, were achieved under optimal reaction conditions. Further, calcination removes carbon deposits in the recovered H-Beta zeolite, but it affects the cycling stability of the catalyst. Meanwhile, the by-products formed during the synthesis of HMF from glucose catalyzed by H-Beta zeolite catalyst were also clearly detected.
研究领域:
催化化学
·
生物质转化
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE
·
2023
·Vol. 34
·期 7
·1-13
·
IF 3.7
Feng Jianlang,Liu Junjie,Wang Yingqu,Diao Jingjing,Kuang Yudi,Zhao Naru
The design of hierarchical porous structure in scaffolds is crucial for bone defect regenerative repair. However, bioceramic materials present a challenge in precisely constructing designed micropores owing to the limitation of forming process. To investigate micropore shape influences bone regeneration in bioceramic scaffolds with macropores, hierarchical porous scaffolds with interconnective macropores (~400 μm) and two types of micropores (spherical and fibrous) were prepared using a combination of direct ink writing (DIW) and template sacrifice methods. Compared to the scaffold with spherical micropores, the scaffold with highly interconnected fibrous micropores significantly improved cell adhesion and upregulated osteogenic and angiogenetic-related gene expression in mBMSCs and HUVECs, respectively. Furthermore, in vivo implantation experiments showed that hierarchical scaffolds with fibrous micropores accelerated the bone repair process significantly. This result can be attributed to the high interconnectivity of fibrous micropores, which promotes the transportation of nutrients and waste during bone regeneration. Our work demonstrates that hierarchical porous scaffold design, especially one with a fibrous micropore structure, is a promising strategy for improving the bone regeneration performance of bioceramic scaffolds. Graphical Abstract
研究领域:
生物材料学
·
组织工程
·
骨科医学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 12
·期 2
·652-663
·
IF 6.119
Chuanyu Yang,Zhongwen Dong,Weifeng Chu,Yanan Wang,Dongpu Zhao,Fucun Chen,Wenjie Xin,Xiangxue Zhu,Shenglin Liu,Longya Xu
A series of beta zeolite catalysts with controllable particle sizes and similar Si/Al ratios were prepared by introducing imidazole (IMD) into the synthesis system and used for liquid-phase transalkylation of diethylbenzene (DEB) with benzene (Bz). The beta zeolite catalyst prepared with an IMD/SiO2 molar ratio of 0.5 possessed the smallest particle size (mean particle size of 119 nm) and the highest DEB conversion of 79.16% under the reaction conditions: 260 °C, 4.0 MPa, WHSV (diethylbenzene) of 2.0 h−1, W(benzene)/W(diethylbenzene) of 3/1, time on stream of 5 h. Then, to elucidate the catalytic roles of acid sites with different strengths, types and positions in beta zeolite in the transalkylation reaction, we carried out Na+ loading on the prepared beta zeolite to eliminate strong acid sites and poisoned the Brønsted acid sites and external acid sites by using 2,4-dimethylquinoline (2,4-DMQ) and triphenylphosphorus (TPP) as toxic reagents, respectively. The results suggested that the moderate and strong Brønsted acid sites of beta-IMD0.5 were the active sites for the liquid-phase transalkylation of DEB with Bz and their utilization rate showed a trend of increasing first and then decreasing. Significantly, 31% of the external Brønsted acid sites of beta-IMD0.5 contributed 81% of DEB conversion. The external acid sites had more contribution to the reaction due to the short diffusion path and fine accessibility.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2024
·
IF 6.5
Bowen Xu,Mengshan Deng,Kehang Lin,Yuexia Wang,Xinqing Lu,Rui Ma,Yanghe Fu,Weidong Zhu
Ti-Beta zeotypes, possessing three-dimensional 12-membered ring pore-opening channels, have shown some superior catalytic performance in the epoxidation of bulky cycloalkenes with hydrogen peroxide (H 2 O 2 ) in comparison with other titanosilicate zeotypes. However, some further improvement on the catalytic activity and selectivity of Ti-Beta zeotypes is still demanded for the industrialization of cycloalkenes epoxidation. In the present work, the catalytic performance of Ti-Beta in cyclohexene epoxidation was significantly improved via the transformation of their closed Ti(OSi) 4 sites into the open Ti(OSi) 3 OH ones by a simple NH 4 F treatment. Based on the extensive characterization results, it is found that the NH 4 F-treated Ti-Beta zeotypes with open Ti(OSi) 3 OH sites, named OH-Ti-Beta, possess a stronger Lewis acidity that is favorable to the production of cyclohexene oxide (CHO) from the epoxidation of cyclohexene with H 2 O 2 , compared to the parent Ti-Beta with closed Ti(OSi) 4 sites. Moreover, OH-Ti-Beta catalysts are reusable after the calcination of the deactivated zeotypes. Hence, it is expected that the current developed NH 4 F treatment can obtain efficient OH-Ti-Beta catalysts industrially applied in cyclohexene epoxidation.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Haoyi Lin,Jiaqi Wang,Boxin Gao,Kaixuan Yang,Guojun Lv,Shixue Qi,Zhiguo Zhu,Hongying Lü
Solvent-free and low-template synthesis of zeolite materials is the future direction of zeolite production, which meets the requirements of green chemistry. Ti-Beta zeolite with opened channel systems of the 3-dimensional 12-membered ring is a promising industrial catalyst in the field of selective oxidations . Herein, nanosized Ti-Beta zeolites were successfully synthesized via interzeolite transformation of siliceous MOR zeolite using sample and commercially available tetraethylammonium hydroxide (TEAOH) as organic structure-directing agents under solvent-free and low-template-content (TEAOH/SiO 2 = 0.2) conditions within a short crystallization time. The crystallization mechanism and Ti coordinated state were thoroughly investigated by numerous characterization techniques. It was found that the hydrothermal synthesis of Ti-Beta-M zeolites obeyed a liquid crystallization mechanism, during which pre-dissolution of the silicon source MOR zeolite was a critical step in achieving successful crystallization. Ti 4+ ions mainly existed in the form of tetrahedrally coordinated states in zeolite framework. Thus Ti-Beta zeolites showed remarkable activity and reusability during the oxidative desulfurization of fuel oil. Moreover, the deactivated mechanism and regenerated method were also studied in detail. This work provides new guidance for solvent-free and low template content synthesis of metallosilicate zeolites.
研究领域:
材料科学
·
绿色化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Tianliang Lu,Xianfeng You,Yanlong Zong,Yongming Xu,Xiaomei Yang,Lipeng Zhou
Production of γ-valerolactone (GVL) from ethyl levulinate (EL) was studied by catalytic transfer hydrogenation (CTH) strategy under mild conditions. Hydrothermally synthesized Sn-Beta zeolites with high crystallinity show high catalytic activity and selectivity. With isopropanol as hydrogen source, 97.1 % GVL yield with 100 % selectivity was given under 110 °C. Crystallization time for synthesis of Sn-Beta showed great effect on the catalytic performance. Sn-Beta- x d catalysts with longer crystallization time (≥7 days) have high crystallinity and better catalytic performance. Firstly, longer crystallization time is necessary for the formation of large amount of Lewis acid sites which catalyze the conversion of EL to GVL. Secondly, high level of silanol groups in Sn-Beta has negative effect on the catalytic performance. High crystallinity means the amount of silanol groups in Sn-Beta- x d at a low level which is favorable for this CTH reaction. Meanwhile, this is why hydrothermally synthesized Sn-Beta shows higher catalytic activity than post-synthesized Sn-Beta in the conversion of EL to GVL. Furthermore, the catalyst was reusable.
研究领域:
化学工程
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 36
·12118-12123
·
IF 7.393
Bohan Li,Yuchi Zhang,Yan Xu,Zhiguo Xia
CsPbBr3 nanocrystals (NCs) with highly efficient narrow-band green emission are promising candidates in display applications. However, the poor stability of CsPbBr3 NCs is always a challenge for future development. Herein, we designed and prepared CsPbBr3 NCs encapsulated into zeolite Beta (denoted as CsPbBr3-Beta) composite via an optimized high temperature solid-state method, and the as-obtained power materials exhibited green emission peaking at 520 nm with a narrow full-width at half-maximum (FWHM) of 25 nm and a high photoluminescence quantum yield (∼61%). We further demonstrated the ultra-high luminescent stability of CsPbBr3-Beta composite by treating under a 150 °C treatment, soaking in water over 30 days, as well as applying in 450 nm light-emitting devices (LED) for 20 days. Ultimately, white-light-emitting devices (WLEDs) constructed by the green-emitting CsPbBr3-Beta composite and commercial blue chip and red K2SiF6:Mn4+ phosphor achieved a color gamut of 123.5% National Television System Committee standard (NTSC) and high luminous efficiency (LE = 95 lm W−1). This work highlights the encapsulation process and feasible solid-state reaction methodology to fabricate CsPbBr3 NCs confined in a microporous molecular sieve with high luminescent stability and performance, significantly expanding its great potential to be used in optoelectronic fields.
研究领域:
材料科学
·
显示技术
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2024
·
IF 5.3
Jiwen Si,Ruifeng Guo,Fagui Qiu,Weikun Ning,Yanbin Sun,Wenqing Li,Qinglong Tao,Shiding Miao
The nanosize Beta-zeolites with hierarchical structures were time efficiently synthesized from natural diatomite and ball clays under 150 °C via a vapor-assisted method with the absence of solvents and F– anions. The Sn(IV) species were incorporated within frameworks of the presynthesized Beta-zeolite using a modified treatment of acid and tetraethylammonium hydroxide (TEAOH). The dealumination and reconstruction of zeolite frameworks were essential. A high atomic ratio of Si/Sn = 63.95 was obtained and the Sn(IV) species were in a tetrahedral coordination in the zeolite framework, as confirmed by various characterizations. The Sn-Beta zeolites show excellent performance in the Baeyer–Villiger oxidation reaction for the conversion of cyclohexanone to ε-caprolactone, with 63.3% conversion of cyclohexanone and superior selectivity for ε-caprolactone. The durability and stability of the catalyst was acceptable, as evidenced by a slight decrease in conversion of only 2.5% after 5 catalytic runs. These demonstrated a prototype practice in synthesizing Sn-Beta zeolites from natural ores and applicable catalysis in green chemistry.
研究领域:
材料科学
·
催化化学
·
绿色化学
✓ 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）