MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Aihu Feng,Yang Yu,Le Mi,Yunzhen Cao,Yun Yu,Lixin Song
The non-framework aluminum is inevitably formed in the process of preparing the ultra-stable Y zeolite (USY), which severely blocks the mesopores of USY zeolite. It is necessary to treat the USY with the appropriate acid and/or alkali. In this paper, the USY zeolite is firstly dealuminated with NH 4 HF 2 solution and then desiliconized with NaOH or NH 4 OH solution. The effect and mechanism of NH 4 HF 2 and different alkali treatments on the structural and textural property of USY zeolite are elaborately demonstrated. It is found that the non-framework Al remaining in the mesopores of USY is significantly removed by the NH 4 HF 2 solution. The desiliconization reaction is more likely to start near the mesoporous wall because the Al concentration in here is low and the repulsive force against OH − is weak. The OH − ions from NaOH solution not only etch the framework Si near the inner wall of the mesopores, but also remove the Si on the surface of NH 4 HF 2 -etched USY zeolite. However, the concentration of OH − ions is too low when NH 4 OH is used as the desiliconization agent, the OH − ions just react with silicon around the mesopores. Therefore, the NaOH/NH 4 HF 2 -etched USY contains both some micropores and macropores, and the NH 4 OH/NH 4 HF 2 -etched USY only possesses more mesopores with pore sizes of ～10 nm. In addition, NaOH/NH 4 HF 2 -etched USY exhibits excellent toluene adsorption performance at low pressure stage, while NH 4 OH/NH 4 HF 2 -etched USY has the highest adsorption capacity on toluene at high pressure stage.
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
CARBOHYDRATE POLYMERS
·
2013
·
IF 3.479
Lipeng Zhou,Zhen Liu,Meiting Shi,Shanshan Du,Yunlai Su,Xiaomei Yang,Jie Xu
Sulfonated hierarchical H-USY zeolite was prepared and characterized by X-ray diffraction, N 2 physisorption, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, temperature-programmed desorption of ammonia, and acid–base titration. It was proved that sulfonic group was successfully anchored onto the hierarchical H-USY zeolite. The acidity of the hierarchical H-USY was remarkably improved. Sulfonated hierarchical H-USY zeolite was efficient for the hydrolysis of hemicellulose and cellulose. The yield of TRS for hydrolysis of hemicellulose reached 78.0% at 140 °C for 9 h. For hydrolysis of α-cellulose, 60.8% conversion with 22.4% yield of glucose was obtained. Even for microcrystalline cellulose, 43.7% conversion with 15.1% yield of glucose can be obtained. These results are much higher than those obtained over hierarchical H-USY zeolite, indicating that both the acidity and the pore structure determine the activity of zeolite as catalyst in the hydrolysis of biomass.
研究领域:
化学工程
·
生物质能
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chem Catalysis
·
2024
·
IF 11.5
Xue Yang,Boxu Gao,Wanyi Li,Kaige Hou,Kexin Yan,Tianlan Yan,Sinong Wang,Yahong Zhang,Lei Wang,Yi Tang
Precisely tailoring the location and strength of Brønsted acid is crucial for the catalytic cracking of polyolefins. Here, by simple sodium cation exchange ( x Na-USY, where x is the Na/Al ratio), it was unexpectedly discovered that x Na-USY ( x < 0.5) displayed a lower cracking temperature of polypropylene (PP) with optimum performance and excellent reproducibility at x = 0.38, rather than pure H-USY, as generally believed. Combining spectroscopic and microstructural characterizations, a putative mechanism was proposed from the perspective of proton location and acid strength. When lacking strong Brønsted acid near site II, PP tended to cleave into longer alkane fractions at low temperatures and volatilized directly, exhibiting significant apparent cracking capacity. Meanwhile, the lower distribution of olefins and aromatics remarkably reduced coke generation at high temperatures. These findings not only shed light on the optimization of plastic degradation catalysts but also expand our knowledge of the zeolitic acid-catalyzed cracking process.
研究领域:
催化化学
·
材料科学
·
能源化工
✓ 已验证
DOI
高影响因子
ChemCatChem
·
2022
·Vol. 14
·期 12
·e202200274
·
IF 5.497
Na Ji,Shuai Cheng,Zhichao Jia,Hanyang Li,Poknam Ri,Shurong Wang,Xinyong Diao
Graphical Working together : The establishment of Co 0 -Al 2 O 3 @USY interface via in-situ growth of CoAl-LDH on USY surface rendered the high activity in HDO of lignin to naphthenes which were attributed to the synergetic effect between Co 0 sites and USY, in which Co 0 sites were responsible for hydrogenation and acid sites on USY were responsible for deoxygenation. To enhance the catalytic activity and stability of metal catalysts in the hydrodeoxygenation of lignin derivatives into naphthenes, a bifunctional Co−Al 2 O 3 @USY catalyst was fabricated by the reduction of CoAl layered double hydroxide in-situ grown on the USY zeolite. In the hydrodeoxygenation of guaiacol, a 100.0 % conversion with cyclohexane yield up to 93.6 % was achieved at 180 °C, 3 MPa for 4 h, which should be the hitherto lowest reaction temperature that has been reported over Co-based metal catalysts. This catalyst was also relatively stable with 5 runs and exhibited excellent catalytic performance in the hydrodeoxygenation of other lignin model compounds and even real lignin feedstock into naphthenes. The high-efficiency of Co−Al 2 O 3 @USY was attributed to the synergistic effect between well-dispersed small Co nanoparticles and abundant acidic sites on the USY surface, while the outstanding stability was attributed to the anchoring effect of Al 2 O 3 matrix to Co nanoparticles which avoided the leaching of Co species and particle agglomeration. This work provides a potential strategy for the design of an efficient and stable catalyst for lignin utilization.
研究领域:
催化化学
·
能源化学
·
材料科学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY COMMUNICATIONS
·
2022
·
IF 3.428
Bo Meng,Shenyong Ren,Zhi Li,Weiyu Song,Qiaoxia Guo,Baojian Shen
Decreasing steam treating temperature of zeolite Y to prepare USY has great attraction for industrial production of FCC catalysts, which is often operated at high temperature thus leading to huge energy consumption. Heteroatoms in the framework of zeolite Y are easier to be removed under steam condition, but the introduction of heteroatoms often leads to the decrease of relative crystallinity of zeolite. When Ga 3+ is introduced into the framework of zeolite Y, high crystallinity is well maintained in this work. Interestingly [Al, Ga]-NaY can be treated at low steam temperature to form [Al, Ga]-USY with very good mesoporosity and high framework SiO 2 /Al 2 O 3 ratio. The sample [Al, Ga]-NaY-8 has a distinctive micropore size distribution at 0.92 nm which is much bigger than conventional microporous NaY. DFT study disclosed the reason of low temperature steam treatment. The catalytic cracking of 1,3,5-TIPB and n -octane showed that the catalyst [Al, Ga]-USY obtained at lower steam treating temperature presented good performance.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
·
2017
·
IF 4.636
Wenwu Zhou,Qing Zhang,Yasong Zhou,Qiang Wei,Lin Du,Sijia Ding,Shujiao Jiang,Yanan Zhang
USY zeolites have been modified by incorporation of gallium, phosphorus and a combination of gallium and phosphorus by wetness impregnation method using gallium nitrate and ammounium phosphate diabasic, and the corresponding NiMo supported hydrodesulfurization (HDS) catalysts have been prepared for HDS of an inferior FCC diesel. The individual physical-chemical properties of the modified USY zeolites and the series NiMo supported catalysts were characterized using XRD, N 2 -adsorption-desorption(BET), NH 3 -TPD, Py-FTIR, H 2 -TPR, HRTEM and XPS methods, and their catalytic performances for an inferior FCC diesel HDS were assessed. The results show that both gallium and phosphorus modification can modulate the acid property of USY zeolite and weaken the interaction between the active metal and the supports, thus enhancing the degree of sulfidation and the dispersion of Mo species that are beneficial for the HDS of highly refractory organosulfur compounds. The highest HDS and HDN efficiencies of 99.7% and 99.6%, respectively, were observed over the catalyst containing the PGaUSY zeolite. More importantly, gallium modification of the USY zeolite promotes the hydrodesulfurization of all organosulfur compounds, and especially 4,6-DMDBT, in the FCC diesel and phosphorus modification of the USY zeolite promotes the hydrodesulfurization of most organosulfur compounds except for 4,6-DMDBT in the FCC diesel.
研究领域:
催化化学
·
石油加工工程
✓ 已验证
DOI
高影响因子
CATALYSIS LETTERS
·
2022
·Vol. 153
·期 7
·2107-2114
·
IF 2.936
Zhao Wenli,Niu Xiaopo,Liu Guangni,Zhang Xiurong,Wang Qingfa
Three kinds of Pt nanocrystals with different morphologies (5 nm cubes, 10 nm cubes and 5 nm truncated octahedrons) were synthesized and employed to fabricate Pt/CNT-USY catalysts for selective ring opening of decalin. The 5 nm truncated octahedral Pt/CNT-USY with exposed (100) and (111) facets exhibited higher yield of ring-opening products (53.9 wt%) than the CNT-USY-supported 5 nm cubic Pt catalyst enclosed by the (100) facets (39.6 wt%). Moreover, the 5 nm cubic Pt showed better catalytic activities compared to the 10 nm cubic Pt/CNT-UST catalyst, which ascribed to the smaller size of Pt NCs enriched more revealable metal active sites. DFT calculations demonstrated that the adsorption of decalin on Pt (111) was stronger than that on Pt (100) facets, which was profitable for the selective ring-opening reaction. Graphical Abstract
研究领域:
催化化学
·
材料科学
·
理论计算化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2018
·
IF 3.849
Binglin Chen,Guizhuan Xu,Zhangbin Zheng,Dongxiang Wang,Caihong Zou,Chun Chang
An efficient and green conversion process of producing 5-ethoxymethylfurfural (EMF) from corn stover was developed. The solid zeolite USY provided the good catalytic performance in ethanol medium with tetrahydrofuran (THF) as co-solvent, which can promote the formation of EMF, reducing the formation of ethyl levulinate and 5-hydroxymethylfurfural. The reaction conditions were optimized via response surface methodology leading to a maximum EMF yield of 21.8% in ethanol/THF (volume ratio 1:1) under the conditions of 168 °C, 1 wt% USY loading and 2.9 h. Meanwhile, USY can be reused in five consecutive reaction runs with high activity, upholding the same initial activity and structural integrity. A plausible reaction pathway for the conversion of corn stover to EMF in ethanol/THF medium was further proposed. This study showed that the improved catalytic system presents an efficient method for direct production of EMF from lignocellulosic biomass.
研究领域:
生物质化学
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Luming Wang,Guoliang Zhang,Hui Zhao,Gang Wang,Zengxi Li,Chunshan Li
With the development of green chemistry, researchers are eager to develop separable and recyclable catalyst for methyl propionate production through ethylene hydroesterification. Herein, a novel zeolite-encapsulated Pd complex was developed for ethylene hydroesterification with CO and methanol to methyl propionate. The introduced Pd component is coordinated with 1, 2-bis (di- tert -butyl phosphinomethyl) benzene ligand to form Pd complex, which is encapsulated in USY zeolite. This scheme solves the challenge of coupling phosphine-palladium complexes with acid promoters as heterogeneous catalysts. It was found that the increasing density of Brønsted acid sites on USY zeolite favors the ethylene hydroesterification. Furthermore, the influences of catalyst preparation and reaction conditions on the catalytic performance were assessed. As a result, the ethylene conversion could reach 99 % with MP selectivity of 100 % under the optimal condition. In addition, the catalytic heterogeneity and stability of zeolite-encapsulated Pd complex were investigated.
研究领域:
催化化学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2025
·Vol. 155
·期 8
·1-12
·
IF 2.4
Ma Xueqin,Shen Liuwei,Shi Gaolei,Zhang Xingguang
The selective oxidation of 5-hydroxymethylfurfural (HMF) to value-added products plays an important role in biomass catalytic transformation, which essentially depends upon design of highly efficient and selective catalysts. This study aims to identify contributions of silanols (Si-OH groups) on Ag/USY catalysts to regulating catalytic performances in selective oxidation of HMF to HMFCA (5-hydroxymethyl-2-furancarboxylic acid), by means of aluminium tri-sec-butoxide (AlBO) modification to suppress Si-OH groups of USY and 2,6-di-tert-butylpyridine (2,6-DTBPy) selective poison to shield Brønsted acid sites in the reaction system. The catalysts are characterized by XRD, BET, TEM, XPS and FT-IR to examine the crystal structures, surface areas, porosity, morphology, Ag distribution, chemical states, and surface adsorptive properties. The HMF conversion (44-49.2%) slightly changes with increasing AlBO content, whereas the HMFCA selectivity gradually goes down from 56.2 to around 22.1% and the levulinic acid (LA) selectivity minorly raises from 5.6 to 12.8%. The production of LA originates from enhanced Brönsted acid sites after AlBO modification, and the decline of HMFCA selectivity is principally attributed to the suppression of Si-OH groups that weakens the interaction between HMF reactants and catalysts. This work provides new insights into the role of surface modification in tailoring metal and zeolite-based catalysts for organic conversions. Graphical
研究领域:
催化化学
·
生物质转化
·
化学反应工程
·
材料科学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2023
·
IF 6.1
Dingkai Wang,Mingyu Cui,Yanjun Li,Wei Zhao,Shangshang Ma,Zhijie Jiang,Xutang Liu,Chong Liang,Rujuan Li,Long Ma,Yanmin Song,Xian-Yong Wei
The facile, green, and efficient strategy for the separation of lignin from straw and subsequent production of value-added chemicals is crucial to the current utilization of straw. Herein, up to 23.72% of lignin was isolated from wheat stalk over cheap and green 1-(3-sulfobutyl) triethylammonium hydrogen sulfate ([BSTEA]HSO4) in aqueous ethanol (Vethanol: Vwater = 4:1). The acquired lignin was verified as a p-hydroxyphenyl-guaiacyl-syringyl type, which had a narrower molecular weight distribution, better thermal stability, and higher purity compared with those of the lignin obtained using 1-methyl-3-(4-sulfobutyl)-imidazolium hydrogen sulfate and 1-(3-sulfobutyl) pyridinium hydrogen sulfate. Moreover, a carbohydrate-rich liquid containing [BSTEA]HSO4 was obtained by water removal from the waste liquid after lignin separation and further converted to ethyl levulinate (EL) by a one-pot process in the presence of inexpensive and stable USY zeolite. The yield of EL reached 30.23% at 200 °C for 60 min over the presence of 40% [BSTEA]HSO4 and 60% USY zeolite. Under optimal conditions, the yields of lignin and EL can respectively reach 83.89 and 72.28% of those catalyzed by a fresh catalyst after five cycles. In short, the above-mentioned methods present a green, economic, and efficient route for the extraction of lignin and further treatment of the liquid waste generated during the extraction process.
研究领域:
生物质能
·
绿色化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Wei Zhou,Wenwei Zhang,Xueqin Ma,Haichen Lai,Xingguang Zhang
Metal-zeolites catalysts are of great importance in selective organic conversions. Zeolites possess features of highly-ordered porous network, adjustable acidic properties (Brønsted/Lewis), spatial nanoconfinement effects, unique shape selectivity and the strong (hydrothermal-) stability. The role of zeolite hydroxyl (z-OH) groups, such as bridging ones in Si-O(H)-Al (B acids) and terminal ones in Al-OH and Si-OH (silanols), in catalysis is an interesting topic, particularly when they are not catalytic active sites, while they affect the catalytic performances. This study comprehensively investigated series of Au/USY catalysts in the selective oxidation of benzyl alcohol to benzaldehyde and clarified the dominating contributions of Al-associated z-OH groups to affecting catalytic conversions and selectivity via altering the Si/Al ratio and reducing z-OH groups by amorphous silica species derived from diethoxydimethylsilane under high-temperature calcination. The catalysts were characterized by XRD, BET, TEM, XPS, UV/Vis, FT-IR and in-situ DRIFT to investigate crystal structures, textural properties, morphologies, size distribution, chemical state of gold, acidity, and adsorptive properties. The experimental results proved that zeolites with a higher amount of z-OH groups tuned by Si/Al ratios or by diethoxydimethylsilane silylation exhibited higher catalytic activity because of the adsorption effect. Finally, a possible mechanism was discussed based on the experimental results and literature.
研究领域:
催化
·
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）