The pore-opening size of NaY zeolite was finely controlled by chemical liquid deposition method. By reacting silicon alkoxide with the adsorbed water or surface hydroxyl group of the zeolite, a thin layer of silica was deposited on the external surface and narrowed the pore-opening size of the zeolite effectively. A series of NaY zeolite samples with different amount of silica deposition (SiNaY) were prepared and characterized by IR spectroscopy and adsorption measurements. It was found that after deposition and calcination the zeolite framework structurre, pore volume and internal surface properties were essentially unaltered. The shape-selective separation of p-xylene/1, 3, 5-trimethylbenzene, 2-methylnaphthalene/1-methyl- naphthalene, 1, 2, 4-trimethylbenzene/1, 3, 5-trimethylbenzene, p- xylene/m-xylene and p-cresol/m-cresol liquid mixtures with difference molecular dimensions on SiNaY was investigated. The separation of mixture isomers with molecular diameters close to the pore size of the zeolite can be achieved successfully.

Key words: CRESOL, INFRARED SPECTROPHOTOMETRY, ZEOLITE, DIMETHYLBENZENE, ADSORPTION, SILICON OXIDE, TRIMETHYLBENZENE, METHYLNAPHTHALENE