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

A single phase Na- X zeolite was synthesized from pretreated oil shale ash by alkaline fusion and hydrothermal treatment. Effects of the NaOH concentration,crystallization time and 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 of pretreated oil shale ash at 600 ℃ for 1 h,and crystallization at 80- 100 ℃ for 8- 10 h with NaOH concentration of 3- 3. 5 mol · L- 1. Na- A zeolite appears when decreasing NaOH concentration, crystallization time or temperature,and an unnamed zeolite emerges when prolonging crystallization time or raising crystallization 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 2m2·g- 1,larger than that of multiple zeolite powders.