个人信息Personal Information
教授
博士生导师
硕士生导师
性别:男
毕业院校:中科院大连化学物理研究所
学位:博士
所在单位:化工学院
学科:工业催化. 能源化工
办公地点:西部校区化工实验楼B-323
联系方式:0411-84986326
电子邮箱:wpzhang@dlut.edu.cn
Insights into the Topotactic Conversion Process from Layered Silicate RUB-36 to FER-type Zeolite by Layer Reassembly
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论文类型:期刊论文
发表时间:2013-03-26
发表刊物:CHEMISTRY OF MATERIALS
收录刊物:SCIE、EI、Scopus
卷号:25
期号:6
页面范围:840-847
ISSN号:0897-4756
关键字:topotactic conversion mechanism; layered zeolite precursor; RUB-36; FER-type zeolite; layer reassembly
摘要:Layered RUB-36 and PREFER (lamellar precursor of ferrierite) are the precursors of CDO and FER-type zeolites, respectively. Both are composed of the same ferrierite (FER) layer building blocks. Topotactic conversion from RUB-36 to pure silica zeolite ZSM-35 has been demonstrated in the presence of a surfactant cetyltrimethylammonium hydroxide (CTAOH). The transformation mechanism of this process was revealed, for the first time, by the detailed investigations of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal analysis, and one- and two-dimensional (2-D) solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) as well as theoretical simulations. During swelling at room temperature, cetyltrimethylammonium cations (CTA(+)) replacing the original template were intercalated into FER layers to expand the interlayer distance remarkably and consequently to destroy the strong hydrogen-bonding interactions between the layers. 2-D H-1-Si-29 heteronuclear correlation (HETCOR) NMR indicates that the surfactant polar heads approximate the FER layers in swollen RUB-36. After deswelling, only a small amount of CTA(+) cations with long tails lay in the void space between the FER layers. The Monte Carlo simulations on the deswollen RUB-36 further elucidate the occlusion of CTA(+) cations in the pre-10 member ring of the layered ferrierite precursor, which may act as the structure-directing agent for the formation of FER-structured zeolite. The FER layer reassembly from the alteration of CTA(+) conformation at the interlayers is of key importance to the topotactic transformation of RUB-36 to FER-type zeolite by the dehydration-condensation reaction. This may open up more applications in the lamellar zeolite system by the layer restacking approach.