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
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
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
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
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
GREEN CHEMISTRY
·
2020
·Vol. 23
·期 2
·912-919
·
IF 9.48
Lulin Wang,Fengan Han,Guangyi Li,Min Zheng,Aiqin Wang,Xiaodong Wang,Tao Zhang,Yu Cong,Ning Li
High-density cyclic hydrocarbons were first synthesized with high carbon yields by a one-pot transfer hydrodeoxygenation of a polycarbonate (PC) using isopropanol as the solvent and hydrogen donor at the same time. RANEY® nickel was found to be an effective catalyst for the conversion of the PC in isopropanol. Over it, the pure PC pellet was completely converted to a mixture of C6–C15 oxygenates, aromatics and cycloalkanes after the reaction was carried out at 463 K for 1 h. The catalytic performance of RANEY® Ni was further improved after the introduction of solid acids as co-catalysts. Among the investigated solid acids, ultrastable Y (USY), a commercial acidic zeolite, demonstrated the best promotion effect, which can be explained by its larger pore size and suitable acidity. Under the optimized conditions, an ∼75% carbon yield of C6–C15 cyclic hydrocarbons was achieved from the one-pot transfer hydrodeoxygenation of a chopped DVD disk under the co-catalysis of RANEY® Ni and USY. According to our measurement, the C6–C15 cyclic hydrocarbon mixture as obtained has a high density (0.94 g mL−1), good volumetric net heat of combustion (NHOC) (41.5 MJ L−1) and low freezing point (202 K–188 K). In real applications, it can be used as a potential substitute for currently used high-density aviation fuels.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
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
JOURNAL OF CATALYSIS
·
2020
·
IF 7.888
Junnan Wei,Ting Wang,Huai Liu,Yiqiang Liu,Xing Tang,Yong Sun,Xianhai Zeng,Tingzhou Lei,Shijie Liu,Lu Lin
It is highly desirable but challenging to develop a one-pot process for the transformation of fructose into 2,5-bis(isopropoxymethyl)furan (BPMF), a promising biofuel component, because a cascade sequence involving dehydration, reduction, and etherification requires multifunctional acid catalysts. Herein, we propose a facile and firm assembly of Zr/2-methylimidazole (2-MeIM) coordination polymer over USY zeolite (USY@ZrCP) through N-Al bonds formed by the condensation of 2-MeIM and the hydroxyls on USY surface at room temperature. USY@ZrCP possesses an abundance of strong Lewis acid sites with suitable amount of Bronsted acid sites, which are mainly attributed to the highly dispersed Zr(IV) species and the hydroxyls over USY@ZrCP, respectively. Unexpectedly, USY@ZrCP could offer BPMF yield up to 82.6% from fructose in isopropanol by the integration of dehydration, Meerwein–Ponndorf–Verley reduction and etherification in a one-pot strategy. This work proposes a novel approach to prepare highly efficient and robust solid acid catalyst for the catalytic valorization of biomass-derived carbohydrates and their derivatives.
研究领域:
化学工程
·
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
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
危险品化学品经营许可证（带存储）