Preparation of Single Phase Na-X Zeolite from Oil Shale Ash by Melting Hydrothermal Method

A single phrase Na - X zeolite was synthesized from pretreated oil shale ash by alkaline fusion and hydrotherreal treatment. Eff3cts of the NaOH concentration, crystallization time ant temperature on the formation of Na-X zeolite were studied in detail. The single phase Na- X zeolite powders can. be prepared by alkaline fusion o.f pretreated oil shale ash at 600 ℃ .for 1 h, and crystalli-zation at 80 - 100 ℃ .for 8 - 10 h with NaOH concentration of 3 -3. 5 tool · L-1. Na - A zeolite appears when decreasing NaOH concentration, crystallization time or temperature, ant an unnamed zeolite emerges when prolonging crystallization time or raising crystalli-zation, temperature. SEM micrographs suggest that the aggregates of Na-X zeolite particles have perfect dispersity and uniform granular with about 1.5 μm in size, and most of the Na-X zeolite crystals display a regular octahedral structure with the size of about 500 nm. The specific surface area of the powders with single Na-X zeolite phase reaches the maximum value of 488. 163 2 m2· g -1, larger than that of multiple zeolite powders.

水热体系合成NaA/X复合沸石

在无模板剂条件下,采用水热反应体系合成NaA/X复合沸石,研究了原料配比及凝胶化条件对NaA/X复合沸石合成的影响。结果表明,该反应体系钠的优化配比为n(SiO2):n(Al2O3)=2.8,反应的适宜碱度条件为:n(H2O):n(Na2O)=25～30、n(Na2O):n(SiO2)=1.6～3.0,碱度过高或过低均会导致X型沸石的消失。产物为复合沸石,粒径为150nm,分散度较好。产物的钙离子交换能力达到300mg/g,镁离子交换能力优于纯4A、X及高铝P型沸石。