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首页> 外文期刊>Science and Technology of Advanced Materials >Preparation of zeolite-coated cordierite honeycombs prepared by an in situ crystallization method
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Preparation of zeolite-coated cordierite honeycombs prepared by an in situ crystallization method

机译：原位结晶法制备沸石包覆堇青石蜂窝

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摘要

Zeolite thin films were prepared on cordierite (Mg_2Al_4Si_5O_(18)) honeycomb substrates by in situ crystallization using soft hydrothermal conditions. The synthesized zeolite films (zeolite A and ZSM-5) were characterized by XRD, FTIR, SEM, NH_3-TPD, and Ns_2 and propane gas adsorption. Zeolite-A films were prepared by dip-coating on a cordierite substrate in a precursor of molar composition of Na_2O:Al_2O_3. SiO_2 H_2O = 4:1:2:100 and heating in an autoclave at 80℃ for 6-10 h. The resultant zeolite-A films consisted of cubic crystals about 2-3 μm in size, achieving a thickness of 20μm after re-coating. ZSM-5 films were similarly formed using a microporous silica precursor obtained by selective leaching of metakaolinite with tetrapropylammonium hydroxide (TPAOH) as the templating agent. The molar composition of the precursor was NaOH:microporous silica:TPAOH:H_2O = 1:10:1:200. The dipped substrate covered with the wet precursor gel was heated in an autoclave at 150℃ for 24 h. The resultant films were composed of short prismatic < 1 μm crystals achieving thickness of several to 10 μm after re-coating. The microstructure and porous properties of the ZSM-5 films were found to change according to the chemical composition and surface treatment of the cordierite substrates. The presence of a SiO_2-rich interfacial layer between the substrate and zeolite film increased the amount of zeolite formed and the physical adsorption but decreased the solid acidity and amount of chemisorption.
机译：通过在软水热条件下原位结晶，在堇青石（Mg_2Al_4Si_5O_（18））蜂窝基材上制备了沸石薄膜。用XRD，FTIR，SEM，NH_3-TPD，Ns_2和丙烷气体吸附对合成的沸石膜（A型和ZSM-5型）进行了表征。通过在Na 2 O：Al 2 O 3的摩尔组成的前体中浸涂在堇青石基材上来制备沸石A膜。 SiO_2H_2O = 4：1：2：100，并在80℃的高压釜中加热6-10 h。所得的沸石-A膜由尺寸约2-3μm的立方晶体组成，重新涂覆后达到20μm的厚度。使用微孔二氧化硅前体类似地形成ZSM-5膜，该微孔二氧化硅前体是通过用氢氧化四丙基铵（TPAOH）作为模板剂选择性浸出偏高岭土而获得的。前体的摩尔组成为NaOH：微孔二氧化硅：TPAOH：H_2O ＝ 1：10：1：200。将浸有湿前体凝胶的浸渍基材在高压釜中于150℃加热24小时。所得的薄膜由小于1μm的短棱柱晶体组成，重涂后厚度达到几到10μm。发现ZSM-5膜的微观结构和多孔性质根据堇青石基材的化学组成和表面处理而变化。在基底和沸石膜之间存在富含SiO 2的界面层，增加了形成的沸石的量和物理吸附，但是降低了固体酸度和化学吸附的量。

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