University of Twente Student Theses


A study to the effect of cobalt-doping on hybrid silica membranes

Eijkelenkamp, Rik (2013) A study to the effect of cobalt-doping on hybrid silica membranes.

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Abstract:The focus of this research was to study the effect of cobalt-doping on the structure and performance of hybrid silica membranes made with 1,2-bis(triethoxysilyl)ethane (BTESE) as precursor. Sols were made with cobalt concentrations between 7 and 28 mol% and varying amounts of nitric acid and measured for particle size and particle size distribution in a dynamic light scattering apparatus. Cobalt concentrations above 16% gave a bimodal particle size distribution, cobalt concentration of 16% and below gave a mono modal size distribution with particles between 7 and 14 nm. Sols with different dilutions were measured for particle size and showed a decrease in measured particle size when de sol was diluted from 0 times to 15 times. When the sols were diluted more than 15 times the distribution became bimodal. XRD experiments were done on 16% and 22% samples calcined at 400°C in a nitrogen environment. No peaks were found, indicating an amorphous structure which suggest that the cobalt was incorporated in the silica matrix or existed in particles with a non crystalline structure. Single gas permeation experiments were done on 16 mol% cobalt concentration membranes of sols that were diluted 6 and 10 times. The gas permeation data of these membrane were compared to a membrane without cobalt doping and turned out to be higher suggesting a more open structure than standard BTESE membranes. Permselectivity turned out to be lower for H2/N2 and H2/CH4 and higher for H2/CO2 for both the six and ten times diluted sols if compared with standard BTESE. From the cobalt-doped membranes only the H2/CH4 permselectivity was close to two times higher for the ten times diluted sol compared to the six times diluted sol indicating that the membrane made of the more diluted sol had less defects.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:50 technical science in general
Programme:Advanced Technology BSc (50002)
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