CHEMICAL LIQUID DEPOSITION ZEOLITES WITH CONTROLLED PORE-OPENING SIZEAND SHAPE-SELECTIVE SEPARATION OF ISOMERS

The pore-opening size of ZSM-5 zeolite was finely controlled by the ch emical liquid deposition (CLD) method using SiCl4, TiCl4, and SbCl5 as a new type of deposition agents. After deposition the CLD zeolites we re characterized by IR spectroscopy, XPS, NH3-TPD, and adsorption meas urement. Their shape selectivity was compared in the sorption separati on of meta- and para-isomers with different molecular diameters, such as m-xylene/p-xylene, m-dichlorobenzene/p-dichlorobenzene, and m-creso l/p-cresol. The ability of pore size controlling of different depositi on agents depends on their reactivity with the zeolite surface hydroxy l groups and the readiness of migration of their oxides during calcina tion. SiCl4 is more efficient in pore size controlling than Si(OCH3)(4 ) and the other halides. The SiCl4-modified ZSM-5 zeolite samples exhi bit excellent shape-selective separation properties for isomers of dis ubstituted benzene.