INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
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IF 4.326
Yujia Jiang,Haochen Qi,Jiayuan Wang,Xu Sun,Changjiang Lyu,Peng Lu,Ruiqin Yang,Aqsa Noreen,Chuang Xing,Noritatsu Tsubaki
Zeolites’ great momentum in industrial applications will require an efficient route for their synthesis. The conventional methods for zeolite synthesis normally involve expensive reactor setups, where the crystallization occurs at high-pressure conditions. Herein, we proposed an ambient-pressure synthesis (APS) of the NaA zeolite at 120 °C. The reaction setup simply used a glass tube as a reactor and a low-density liquid as a sealant. The optimum synthesis conditions were obtained by using a methylcellulose template and the polyethylene glycol-400 sealant. Compared with that of the conventional hydrothermal process, the barrier of the sealant over the zeolite gel in the glass tube can significantly reduce the synthesis cost, and it also makes the process much safer than the conventional methods.
研究领域:
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
JOURNAL OF MEMBRANE SCIENCE
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2018
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IF 6.578
Xiao-Qing Li,Pei-Yao Zheng,Jia-Kai Wu,Nai-Xin Wang,Shu-Lan Ji,Zhi-hui Yu,Quan-Fu An
Zeolite NaA membranes have been widely used in dehydration of alcohols by pervaporation because of their excellent permeability and selectivity. However, the zeolite NaA membranes were criticized for the poor performance in acidic condition. Herein, we report a simple and effective method to enhance acid stability of zeolite NaA membranes. The key is a positively charged polyelectrolyte complex (PEC) was impregnated on the surface of zeolite NaA membranes. The PEC was synthesized from chitosan (CS) and sodium poly (vinyl sulfonate) (PVS). Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that the zeolite NaA membranes suffered from severe damage in both morphology and crystal structure after contact with acid, while the PEC/NaA composite membranes remained intact. Accordingly, the PEC/NaA composite membranes（1.5 wt% PEC in solution） exhibited excellent water permeability and selectivity in acid solution. For acidic 90 wt% ethanol/water (pH = 3) mixture separation, the permeate flux was 875 g/(m 2 h), the water content in permeate was as high as 99.8 wt% at 40 °C. Meanwhile, the composite membranes showed a good acid stability for more than 200 h and this was attributed to the barrier effect of PEC layer, as well as the protonation ability of -NH 2 groups in PEC. This method is expected to offer great opportunities for the dehydration of organics under acidic conditions.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2019
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IF 5.107
Xuechao Gao,Bing Gao,Hua Liu,Chun Zhang,Yuting Zhang,Ji Jiang,Xuehong Gu
Submicron NaA zeolite seeds were coated on the stainless steel (SS) hollow fiber support by self-assembly method, and then the hydrothermal crystallization and autoclave technique were used to synthesize NaA zeolite membranes. The effects of grafting temperature, grafting time and the size of induction seeds on the membrane performance were extensively investigated. The as-synthesized membranes and zeolite crystals were then characterized by X-ray diffraction, and the morphology and thickness of membranes were examined by scanning electron microscopy. The separation performance of the membrane was evaluated by pervaporation dehydration of 90 wt% ethanol/water mixtures at 75 °C. It was found that the seed-layer should be uniformly coated to induce good continuity for the NaA zeolite membrane layer, where the seeding effect was clearly affected by grafting time, grafting temperature and seed size. The optimal seeding condition was found for a grafting time of 6 h under a temperature of 110 °C, using a seed size of 150 nm. A continuous zeolite membrane layer could be obtained on the surface of the SS hollow fiber, with a separation factor above 10,000 and a permeation flux of 4.22 kg∙m −2 ∙h −1 . The proposed self-assembly method could be readily operated and extended to the seeding process during the preparation of other supported zeolite membranes, providing a good prospect in batch-scale production of SS hollow fiber supported NaA zeolite membranes.
研究领域:
材料科学
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分离技术
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Xiaoling Chen,Ying Wang,Chan Wang,Jingdong Xu,Tiesen Li,Yuanyuan Yue,Xiaotao Bi,Lilong Jiang,Xiaojun Bao
Deep understanding of the formation mechanism is crucial to the rational design and controllable synthesis of zeolites with desired pore architecture and acidity. Herein, we take the synthesis of NaA zeolite from a submolten salt depolymerized kaolin (SMS-K) as an example to elucidate the formation mechanism of NaA zeolite. By using SMS-K as sole Si and Al sources, a highly pure and crystalline NaA zeolite with superior ion exchange ability was synthesized. By using various ex-situ and in-situ characterizations and studying the crystallization kinetics, a plausible formation mechanism of NaA zeolite via the mesoscale reorganization of SMS-K was proposed. The results indicate that the reorganization of SMS-K into NaA zeolite follows the solid-phase transformation route. Upon being mixed with H 2 O, SMS-K that is mainly composed of silicate monomers and chain/ring microstructures is in-situ transformed rapidly into mesoscale intermediates containing double four-membered rings and β cages, sufficient stirring during aging generates more mesoscale intermediates. During the subsequent crystallization process, the mesoscale intermediates are further self-assembled into NaA nanoparticles when theirs amount reaches a maximum, and finally the nanoparticles grow into well-shaped cubic NaA zeolite particles with smooth surfaces through layer spreading. Our work provides the theoretical foundation for the design and green synthesis of zeolites directly from the natural minerals.
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
危险品化学品经营许可证（带存储）