CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Zhiyang Zhang,Mi Hu,Qingfeng Gui,Jing Gu,Wenlong Xu,Qingbo Xiao,Wei Huang
Adipic acid is a valuable chemical used to product Nylon-66, and one of the greenest ways to synthesize it is catalyzing the oxidation of cyclohexane by molecular oxygen in the absence of any other chemicals. However, it is challenging to convert cyclohexane effectively with high selectivity to adipic acid using the available catalysts. In response to the dilemma of achieving satisfactory conversion and selectivity at the same time, a remarkable Au@NaX catalyst is proposed using an improved in-situ crystallization method that exhibits Au clusters surrounded by X-zeolite channels. A 29.5% conversion of cyclohexane and an 85.6% selectivity to adipic acid can be obtained in a one-pot oxidation of cyclohexane at 140 °C, 20 bar O 2 , far exceeding most published results. Since determined by detailed characterizations and DFT calculations, the effective dynamic collaboration between Au clusters and zeolite inner micro-environment is the decisive role for superior catalytic performance. Specifically, the surrounding zeolite channel encourages the adsorption and activation of cyclohexane over the confined Au clusters, resulting in an unprecedented activity. The continuous oxidation of cyclohexanol and cyclohexanone to adipic acid is also vulnerable on the enclosed Au clusters, and the subsequent adipic acid can be further stabilized as a result of the strong interaction of –COOH with Na ± in zeolite channels surrounding enclosed Au clusters. It prevents AA from poisoning active sites and generates a higher selectivity for the desired adipic acid. Our study highlighted the critical significance of the dynamic interaction between metal clusters and the zeolite channel microenvironment. It would shed light on the further high-performance catalysts designs for selective oxidation.
研究领域:
催化化学
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绿色化学
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产品关联
DOI
高影响因子
CHEMICAL PHYSICS LETTERS
·
2020
·
IF 2.029
Hanyang Liao,Ye Li,Haorui Li,Bolin Li,Yuzhi Zhou,Dongbin Liu,Xiaoli Wang
The amidoxime -modified X-type zeolite (AO-XZ) was successfully prepared by using X-type zeolite (XZ) as a carrier, iminodiacetonitrile (IDAN) as a nitrile-based precursor, and loading the amidoxime group onto the XZ. Mesoporous structure of XZ was unchanged after modification and the mechanism of adsorption is ion exchange. The adsorption behavior followed the pseudo-secondary kinetics, indicating that chemical adsorption is dominant. The Langmuir model had a good fitting effect (R 2 ≈ 0.9931), indicating that the adsorption process is dominated by single-layer uniform adsorption, and the maximum adsorption capacity of AO-XZ towards Cs + by Langmuir fitting was 222.2 mg/g. The process of Cs + adsorption by AO-XZ has high adsorption rate (greater than90%) under neutral conditions and common ion competition. Besides, in the dynamic experiment, the adsorption reached the point of failure after 14 h. The above results indicate that AO-XZ has good potential for removing Cs + from radioactive wastewater in future practical applications.
研究领域:
环境科学
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材料科学
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DOI
高影响因子
ADVANCED POWDER TECHNOLOGY
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2018
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IF 2.943
Ting Yang,Caiyun Han,Hang Liu,Liu Yang,Dekun Liu,Jie Tang,Yongming Luo
Na-X zeolite was successfully prepared from low aluminum coal fly ash (LACFA) via fusion-hydrothermal treatment. The influence of various synthesis parameters was investigated, including aluminum additives (AlCl 3 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O, AlF 3 ·3H 2 O and NaAlO 2 ), dosages of NaAlO 2 , weight ratio of LACFA/NaOH, crystallization temperature and time. The results indicated that the addition of Al species played a key role in the synthesis process of purity Na-X zeolite, and the corresponding relative crystallinity of the obtained samples was in the order of Na-X zeolite (Al) ≫ Na-X zeolite (Cl) > Na-X zeolite (N) > Na-X zeolite (F) (Here, “Al”, “Cl”, “N” and “F” represent NaAlO 2 , AlCl 3 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O and AlF 3 ·3H 2 O, respectively). And the optimal operating conditions were: the weight ratio of LACFA/NaOH = 0.83, short crystallization time 360 min, low crystallization temperature 90 °C and 0.038 mol NaAlO 2 . Additionally, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), Fourier Transforms Infrared (FT-IR) and Scanning Electron Microscopy (SEM) were employed to determine the resultant samples. Based on the results of As(V) adsorption experiment, the experimental data was suitable fitted by Freundlich adsorption isotherm model, and the theoretical maximum adsorption capacity was 27.79 mg/g at pH = 2.14. The kinetics studies suggested that “surface reaction” was the rate-determining step of adsorption process, and the thermodynamics studies indicated that the adsorption process was spontaneous and endothermic. These results deemed that the LACFA was suitable for preparing Na-X zeolite (Al) , and the obtained Na-X zeolite (Al) was served as a promising adsorbent to remove As(V) from acid wastewater.
研究领域:
环境科学
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材料科学
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产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
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IF 3.764
He Han,Min Liu,Hong Yang,Chuan Shi,Shutao Xu,Yingxu Wei,Zhongmin Liu,Chunshan Song,Xinwen Guo
One of the potential processes for making styrene monomers is side-chain alkylation of toluene with methanol, and X zeolites (a common type of faujasite) have been identified as one of the most suitable catalysts for this reaction. In this work, a series of X zeolites with different micro- and meso-porosities and acid–base properties are prepared by post-treatments of NaX zeolite and their catalytic performances for the side-chain alkylation of toluene with methanol are evaluated. This study shows that intracrystalline mesopores could be introduced into the NaX zeolite while retaining adequate microporosity through controlling the intensity and sequence of ammonium-exchange (AE) and/or dealumination (DA) post-treatments. The loss in basicity of the resulting mesoporous X zeolites due to AE and/or DA treatments could be compensated and even enhanced by the subsequent cesium modifications. As catalysts for the side-chain alkylation reaction, the study shows that while introducing appropriate mesopores into X zeolites enhances molecular diffusion, the restriction effect of micropores is proven to be critical for their catalytic activity. Moreover, it is the acid–base property rather than the pore structure of the post-treated X zeolites determining their catalytic activity and selectivity for the side-chain alkylation reaction.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
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2022
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IF 7.968
Wen-Jing Wang,Wen-Yan Pan,Xue-Ling Wei,Bo Song,Yu-Ling Luo
Zeolite membranes possess great application prospects in purifying chemical substances, however, the current synthetic conditions are insufficient to eliminate defects, restricting the industrial applications of zeolite membranes. In this study, compact X-type zeolite membranes were synthesized in hetero-alkali-metal cation synthesis solutions via in-situ heating method. The obtained X-type zeolite membrane possessed a methanol/methyl tert-butyl ether (MTBE) separation factor greater than 10,000 at a permeation flux of 1.3 kg m −2 h −1 . A possible mechanism for the influence of hetero alkali meatal cations on the formation of zeolite membranes was proposed, which involved structural induction and regulation of the rates of crystal nucleation and growth. The hetero-alkali-metal cations entering the zeolite crystal caused distortion of the crystal structure, which promoted transformation of the zeolite crystal structure and accelerated crystal growth. Meanwhile, the rates of crystal nucleation and growth on the surface of the support were regulated by the cooperative action of the hetero-alkali-metal cations and Na + in the synthesis solution through their solubility for the aluminosilicate gel, leading to the formation of compact zeolite membranes. This method controlled the zeolite crystal structure and compactness of the zeolite membrane by simply adding hetero-alkali-metal cations to the synthesis solution, providing a new idea for designing defect-free membranes with high permselectivity.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
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IF 15.1
Zhe Hong,Chuanfang Xiong,Xin Wang,Fangtao Huang,Lei Li,Zhirong Zhu
Side-chain alkylation of toluene with methanol is a potential route for producing styrene. However, there are several challenges that prevent its industrialization, comprising the decomposition of methanol to CO and H 2 , and unavoidable by-products of ethylbenzene. Herein, we disclose that X zeolite after ion exchange of ammonium have an interesting and unexpected feature. It can modulate the Lewis acid-base pairs, via in situ ammonia production from ammonia pools, meanwhile, lead to more Cs + species left in the zeolite, thereby constructing a superior catalyst for toluene side-chain alkylation. Especially for CsX-ex-AP catalyst, the ammonia pools effect (APE) in CsX-ex can achieve both higher toluene conversion and styrene selectivity. Furthermore, the methanol utilization efficiency increases significantly after APE reduction, indicating the selective catalysis for non-oxidative methanol dehydrogenation by in situ NH 3 production from ammonia pools. In addition, the APE reduction contributes to the formation of the active intermediates of m -HCOO* species, which is another reason responsible for the superior performance.
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
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
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2024
·Vol. 40
·期 6
·1192-1200
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IF 3.1
Huang Yitong,Wang Yaquan,Liu Wenrong,Bu Lingzhen,Qu Liping,Chu Kailiang,Guo Niandong,Zhang Xian,Su Xuemei,Li Yaoning,Sang Juncai
A series of low silica X zeolites (LSX) was synthesized through a seed-iteration approach, based on the seed addition strategy, and then loaded with lithium ions by an ion exchanging method to obtain high N 2 adsorption capacity. These zeolites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA) and N 2 adsorption-desorption, and the adsorption capacity of N 2 and O 2 was evaluated by the vacuum pressure swing adsorption (VPSA) operation. The results showed that the nucleation period of the synthetic process could be effectively shortened by adding seed; as the seed iterations increased, the specific surface area and pore volume of the zeolites increased; the higher specific surface area and the pore volume, the higher the extent of the N 2 adsorption capacity, with the maximum reaching 28.05 cm 3 /g. However, there were no significant differences in the adsorbed capacity of O 2 by each sample. Therefore, the N 2 /O 2 separation factor also increased gradually with iterations, with the maximum up to 6.61.
研究领域:
材料科学
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化学工程
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吸附技术
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2025
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IF 5.4
Ruijia Dai,Yongqi Zhao,Qingchun Zhai,Shaoyu Wang,Hua Li,Xingxing Chen,Jianglong Yu,Jinxiao Dou
Coal-fired power plants generate substantial quantities of hazardous fly ash and gas pollutants, presenting significant environmental challenges. This study introduces an innovative approach to simultaneously address both waste streams by converting coal fly ash (CFA) into high-performance X zeolite adsorbents. The synthesized X zeolite showed exceptional surface area and well-defined crystalline structure, as confirmed by comprehensive characterization using SEM, XRD, FT-IR, BET, Raman, and TPD analyses. The adsorption performance of the synthesized X zeolite was systematically evaluated using low-concentration (1000 ppm) flue gas components including NH 3 , NO, SO 2 , CO 2 , and C 7 H 8 across operating temperatures of 20–100 ℃. Maximum adsorption capacities at 20 ℃ reached 1.58, 0.38, 1.16, 0.71, and 0.65 mmol/g for NH 3 , NO, SO 2 , CO 2 , and C 7 H 8 respectively, with NH 3 and SO 2 showing notably higher affinities. The selective adsorption behavior stems from strong interactions between polar gas molecules and the zeolite framework under combined dispersion and electrostatic forces. In-situ DRIFTs analysis coupled with DFT calculations revealed that bridging oxygen atoms (T-O-T) within the zeolite structure serve as primary adsorption sites, facilitating electron transfer with gas molecules. These findings demonstrate the potential of CFA-derived X zeolite for efficient multi-pollutant removal from flue gases while simultaneously addressing solid waste management in coal-fired power plants.
研究领域:
环境科学
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化学工程
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材料科学
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物理化学
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污染控制技术
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DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
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IF 3.375
Honghua Zhang,Jiakuo Xu,Hongguo Tang,Zhiqiang Yang,Ruixia Liu,Suojiang Zhang
Different metal compositions based on metal-ion-modified X-type zeolite in the isobutane/2-butene alkylation reaction were investigated. Bimetallic (rare earth (RE) and Cu) supported zeolites catalysts owned better lifetime and selectivity than those modified by the single metal (La, Ce, or Cu). CuLaX performed best with a 15 h catalytic lifetime obtained after hydrogen activation when the content of copper was 0.197 mmol/g. The possible reason is that the RE X-type catalyst modified with copper ion increases the concentration of strong Brønsted acid sites, which is more favorable for the hydride transfer in the alkylation. Herein, the valence of copper ions is of importance to the alkylation performance. A mechanism was proposed wherein the existence of Cu+ inhibited the progress of the oligomerization reaction and then prolonged the lifetime of the catalyst through decreasing the desorption concentration of 2-butene in the active site.
研究领域:
化学工程
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催化
·
石油化学
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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）