| abstract |
1342977 Attrition resistant zeolites W R GRACE & CO 24 Sept 1971 [24 Sept 1970] 44725/71 Heading C1A Attrition resistant zeolites having particle size in the range 50-200 Á are prepared by, (a) subdividing and dehydrating, e.g. spraydrying, a slurry of SiO 2 and Al 2 O 3 to solids of size 50-200 Á, (b) mixing the particles with a solution of sodium hydroxide or silicate, with or subsequently, as nucleation centres, particles of a zeolite which are amorphous to X-rays and have an average size below 0À1 Á, e.g. down to 0À05 Á, and then (c) hydrothermally crystallizing the reaction mixture at a temperature of 80-120‹ C. A slurry of clay, SiO 2 - Al 2 O 3 gel, or a cracking catalyst containing 10-40% by wt. Al 2 O 3 may be used. The zeolite may be a faujasite having a SiO 2 /Al 2 O 3 mol. ratio > 3, and a surface area of 230-929 m<SP>2</SP>/g, a pore size of 5-15Š and an attrition index < 40. The nucleation centre may have a SiO 2 /Al 2 O 3 ratio of 2À3-2À7. The zeolite product may be R.E. exchanged to 3% Na. |