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Development of CVD Zeolites with Fine Molecular Sieving Function

具有精细分子筛分功能的CVD沸石的研制

基本信息

批准号：
04555198
负责人：
NIWA Miki
金额：
$ 2.18万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

1. Continuous-flow CVD Method to control the Pore-opening Size of ZeolitesA continuous-flow CVD (chemical vapor deposition) method by which a large amount of zeolite could be modified uniformly to control the pore-opening size was studied. Uniformly deposition of silica was possible on the Na-mordenite at 593 K, but on the H-mordenite only at low temperature where no secondary reaction of produced methanol was observed. Subsequent elevation of temperature after the deposition on the H-mordenite deteriorated the structure to obtain the non-homogeneous pore-opening size. The structure of deposited silica was however modified to finely control the pore-opening size by the treatment by water vapor at 673 K due to the loss of coke as well as the subtle change of the deposit silica.2. Molecular Sieving Property of CVD Zeolites(1) The pore-opening size of NaCaA was controlled finely so that the separation of lower olefins such as ethylene, propylene, and butene was possible due to the length of molecules.(2) ZSM-5 was modified to obtain the shape-selectivity of cracking of octane. The selectivity was observed only at high temperature (773 K) because of the mechanism of cracking.(3) Alkylation of methylnaphthalene was carried out, and the beta-selectivity was enhanced on the CVD zeolites. However, the enhancement was caused by the inactivation of external surface rather than by the pore-size control.

1.连续流动化学气相沉积法控制沸石的孔径研究了一种连续流动化学气相沉积法，通过该方法可以对大量沸石进行均匀改性以控制沸石的孔径。均匀沉积的二氧化硅是可能的Na-丝光沸石在593 K，但在H-丝光沸石上，只有在低温下，没有观察到二次反应产生的甲醇。在H-丝光沸石上沉积后随后的温度升高使结构劣化，从而获得不均匀的孔开口尺寸。然而，在673 K下用水蒸气处理，由于焦炭的损失以及存款二氧化硅的细微变化，沉积二氧化硅的结构被改性以精细地控制孔开口尺寸. CVD沸石的分子筛性质（1）NaCaA的孔开口尺寸被精细地控制，使得由于分子的长度，低级烯烃如乙烯、丙烯和丁烯的分离是可能的。(2)对ZSM-5分子筛进行了改性，以获得辛烷裂解的择形性。由于裂解机理的原因，仅在高温（773 K）下观察到选择性。(3)在CVD分子筛上进行了甲基萘的烷基化反应，提高了甲基萘的β-选择性。然而，这种增强是由外表面的失活而不是由孔径控制引起的。