Supported and unsupported sol-gel alumina membranes

Thesis/Dissertation · Tue Dec 31 23:00:00 EST 1991

OSTI ID:6914909

Yu, C

Synthetic permselective membranes are useful for many chemical separations. Inorganic membranes have been considered due to their thermal and chemical stability. Sol-gel processing is an attractive method for membrane preparation, because it produces microporous ceramic preforms. In this study, an in-situ sol-gel process was investigated for supported alumina membranes, and a two-step sol-gel process was investigated for unsupported alumina membranes. Aluminum sec-butoxide (ASB) was used as the precursor. XRD, thermal analysis, FTIR, SEM, TEM, nitrogen adsorption/desorption analysis, and gas permeation measurements were the basic techniques used for membrane characterization. Supported alumina membranes were synthesized by attaching an alumina gel layer to the outside of a porous alumina tube. An in-situ sol-gel coating technique, involving the permeation of water through the tube wall to control the rate of hydrolysis, was developed. Three different approaches, referred to as flowing water approach, complete wetting approach, and partial wetting approach, were studied for delivering the water. Isopropanol was the best solvent compared with ethanol and butanol. By diluting ASB with isopropanol in a 1:25 volume ratio, an optimum reactivity was found that allowed a gel layer to grow which could remain intact throughout drying. A multistep drying procedure was established. The gel coating was adherent and insoluble in water. It followed the contour of the supporting surface, and withstood light abrasion. The coating remained effective after 800[degrees]C firing. Unsupported alumina membranes were synthesized by casting an alumina sol, generated in a two-step process, onto polystyrene petri dishes. Drying conditions for the gel sheets were optimized. The gel sheets were dried and heated without warping or cracking. The membranes of 80 microns thickness could support a pressure differential of 1 atm.

• Research Organization: Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Facultad de Quimica
• OSTI ID: 6914909
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
INORGANIC POLYMERS
MEMBRANES
OPTIMIZATION
OXIDES
OXYGEN COMPOUNDS
PERMEABILITY
POLYMERS
SOL-GEL PROCESS
SUPPORTED LIQUID MEMBRANES