PORE-SIZE CONTROL OF NAY ZEOLITE BY CHEMICAL LIQUID DEPOSITION AND SHAPE-SELECTIVE SEPARATION

The pore-opening size of NaY zeolite was finely controlled by chemical liquid deposition method. By reacting silicon alkoxide with the adsor bed water or surface hydroxyl group of the zeolite, a thin layer of si lica was deposited on the external surface and narrowed the pore openi ng size of the zeolite effectively. A series of NaY zeolite samples wi th different amount of silica deposition (SiNaY) were prepared and cha racterized by IR spectroscopy and adsorption measurements. it was foun d that after deposition and calcination the zeolite framework structur e, pore volume and internal surface properties were essentially unalte red. The shape-selective separation of p-xylene/1,3,5-trimethylbenzene , 2-methylnaphthalene/1-methylnaphthalene, 1,2,4-trimethylbenzene/1,3, 5-trimethylbenzene, p-xylene/m-xylene and p-cresol/m-cresol liquid mix tures with difference molecular dimensions on SiNaY was investigated. The separation of mixture isomers with molecular diameters close to th e pore size of the zeolite can be achieved successfully.