MOLECULES
·
2020
·Vol. 25
·期 4
·771
·
IF 3.267
Hao Xu,YuXia Yu,LongFeng Zhu,ChaoQun Bian,HangLing Zhai,JianYing Tong,HuiZhen Wu,Chao Shen
Preparation of aluminosilicate ferrierite (FER) zeolite nanosheets with controllable thickness in the presence of a sole organic ammonium is attractive, but still challenging. In this report, with the employment ofN,N-diethyl-cis-2,6-dimethylpiperidinium (DMP) as both a structure directing agent and crystal growth inhibitor, aluminosilicate FER zeolite nanosheets, with a variety of crystal thicknesses, ranging from 6 to 200 nm, are successfully synthesized under hydrothermal conditions. Very interestingly, the amount of DMP in the starting gel is the key factor for crystal thickness control of aluminosilicate FER zeolite nanosheets. The obtained FER products, with different thicknesses, are well characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), N2sorption, thermogravimetric analysis (TG), inductively coupled plasma (ICP), and magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. This simple strategy might provide a novel avenue for the synthesis of other zeolite nanosheets with controllable thickness.Keywords:aluminosilicate FER zeolite;morphology control;nanosheet;organic ammonium
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 22
·14183-14189
·
IF 4.036
Yuekun Li,Duozheng Ma,Wenhua Fu,Chuang Liu,Yu Wang,Zhendong Wang,Weimin Yang
The synthesis of zeolites with nanosheet morphology has been attracting extensive attention. Despite the steady progress, the direct synthesis of ultrathin nanosheets of FER zeolite with thickness of less than 10 nm is still a great challenge. Herein we report a facile synthesis of FER zeolite nanosheets (named SCM-37) by using octyltrimethylammonium chloride (OTMAC) and 4-dimethylaminopyridine (4-DMAP) as dual organic templates. The effects of synthesis parameters, including initial molar ratio of SiO2/Al2O3, crystallization temperature and time were investigated. It turned out that the crystallization field of SCM-37 was narrow. A two-step crystallization method was utilized to obtain pure and completely crystallized SCM-37 zeolite. SCM-37 was characterized by multiple techniques, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen physisorption, Fourier transform infrared (FTIR), ammonia-temperature programmed desorption (NH3-TPD) and nuclear magnetic resonance (NMR), and compared with the conventional FER zeolite (C-FER). The two most significant features of SCM-37 are the ultrathin crystal nanosheet and extremely high external surface area. The thickness of SCM-37 along the a-axis is 4∼7 nm, while that of C-FER is over 20 nm. The external surface area reaches 198 m2 g−1, which is over ten times larger than that of C-FER. The catalytic performances of the FER zeolites were evaluated by the cracking of 1,3,5-triisopropylbenzene (TiPB). Although possessing a lower amount of total acid sites, SCM-37 showed higher conversion of TiPB, as well as selectivity to the deep cracking products. The superior performance of SCM-37 was attributed to the higher external surface area arising from the ultrathin nanosheets.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 18
·5435-5448
·
IF 5
Xinyue Hu,Jialing Chen,Shaokang He,Tingyu Liang,Shenke Zheng,Lijun Lu,Chenxi Hao,Kaixin Chen,Tingting Li,Lan Yi,Li Guo,Xiaoqin Wu
Three OP-Fe-FER-x zeolites (with an FER structure) synthesized by a one-pot method with different Si/Al ratios (x = Si/Al =10–30) and similar iron contents (5.4–5.6 wt%) were compared with commercial IM-Fe/SSZ-20 zeolite (with a CHA structure) prepared by an incipient wetness impregnation method to investigate their catalytic activity and hydrothermal stability for the selective catalytic reduction reaction of NOx with NH3 (NH3-SCR). For both fresh (without hydrothermal aging treatments) and aged (with hydrothermal aging treatments) zeolites, the NOx conversions of OP-Fe-FER-x zeolites are much higher than that of IM-Fe/SSZ-20 zeolite, suggesting that the OP-Fe-FER-x zeolites are better catalysts for NH3-SCR than the commercial IM-Fe/SSZ-20 zeolite. Compared with the fresh zeolites, the NOx conversions of all four aged zeolites decrease in the low-temperature range (100–300 °C), while they increase at high temperatures (450–550 °C) to different extents. Based on XRD, N2 physisorption, NH3-TPD, UV-vis, XPS and H2-TPR experiments, the hydrothermal aging process of the OP-Fe-FER-x zeolites is depicted, which consists of partial collapse of the zeolite framework, removal of framework aluminum and iron atoms, and transformation and aggregation of iron species. Detailed characterization reveals that the OP-Fe-FER-x zeolites are more stable than the IM-Fe/SSZ-20 zeolite during the hydrothermal aging treatments. The obvious decline of NH3-SCR catalytic activity for the aged zeolites in the low-temperature range is mainly attributed to the transformation and aggregation behaviors of active isolated Fe3+ species. As for the increase of NH3-SCR activity for the aged zeolites at the high temperatures (450–550 °C), it is mainly attributed to the suppression of the NH3 oxidation side reaction due to the deteriorated NH3 storage capacity because of the loss of massive acid sites during the hydrothermal aging treatments.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2021
·Vol. 8
·期 24
·5277-5285
·
IF 6.569
Shiqing Li,Lu Han,Zhonglin Zhao,Hao Xu,Jingang Jiang,Peng Wu
The lamellar precursor of the FER type zeolite (PREFER) was applied to develop the interlayer expanded zeolite IEZ (interlayer-expanded zeolite)-FER (D4h) with extra-large pores through hydrothermal acid treatment-assisted molecular alkoxysilylation, using 1,3,5,7-tetramethyl cyclotetrasiloxane (D4h) as a silylating agent to interconnect neighboring zeolitic layers. The interlayer expanded structure was well preserved after calcination at 823 K, yielding a hydrophilic material denoted as IEZ-FER(D4h-B). The as-made IEZ-FER(D4h) exhibits expanded interlayer spacing along the a-axis. The 4-membered rings (4MR) exist in IEZ-FER(D4h) as the secondary structure building units, while the methyl groups therein attached result in the hydrophobic properties. The newly formed channel systems are composed of intersecting 14MR and 12MR pores along the [001] and [010] directions, respectively, which are larger than those of the conventional 3D FER. The powder XRD patterns determine that IEZ-FER(D4h) has a crystalline structure with the IMM2 space group and unit cell parameters of a = 28.0285(39) Å, b = 14.0921(6) Å, c = 7.4395(3) Å.
研究领域:
化学
·
材料科学
·
催化
✓ 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）