Inorganic Microporous Membranes for Gas Separation in Fossil Fuel ...

3 Experimental
o of as-made DOH crystals
o of as-made DOH crystals synthesised with traces of titanium (Si/Ti~100)
to assist the burnout by catalytic oxidation
o of DOH being ball milled to reduce the crystal size. The DOH crystals
were ball milled for 4 to 72 hours.
B. calcination in pressurised air: Hot Isostatic Pressure (HIP) calcination was
performed with a vacuum sinter oven of Engineered Pressure Systems
International N.V. Belgium. The samples were calcined between 700 and 900ºC
for 5 hours. During this time the air pressure changed between 1 and 200 MPa
with a frequency between 1 and 8 times.
3.2.3 Dodecasil-1H layer formation
The DOH Zeolite layers were prepared on commercially available alumina disks
(Inocermic GmbH Hermsdorf Germany). A 0.5 wt% suspension of DOH nuclei in H2O
was spincoated 1, 3 or 5 times on the substrates with a Delta+80 7 equipment of SÜSS
Microtec (Table 11). The seeded substrates were heated at 600ºC for 3 hours with a
heating and cooling rate of 1ºC/min. The seeded substrates were located horizontally at
the bottom of a Teflon lined steel autoclave. A clear solution with a molar ratio of
100SiO2:11ADA:267EN:7400H2O was added. Finally, the seeded substrates were
subjected to hydrothermal crystal growth at 200ºC for 24-48 hours.
The second attempt of DOH zeolite layer formation was carried out by depositing a
suspension of 0.25 wt% DOH nuclei in H2O on a substrate. The seeds were dried at
200ºC prior to the hydrothermal step. A clear sol solution with a molar ratio of
100SiO2:5.9ADA:69EN:3500H2O was added. The hydrothermal treatment was
performed at 200ºC for 24 hours. The zeolitic layers were washed with ethanol and H2O
and finally calcined at 700ºC for 5 hours with a heating and cooling rate of 1ºC/min.
Table 11 Seeding and coating properties of DOH membranes
Deposition Nuclei Gel composition Crystallisation
Technique # Deposition steps SiO2:ADA:EN:H2O Temperature Time
A 1 100:11:267:7400 200ºC 48h
Spin-coating, 600ºC B 3 100:11:267:7400 200ºC 48h
C 5 100:11:267:7400 200ºC 24h
D 1 100:5.9:69:3500 200ºC 24h
Depositing, 200ºC E 1 100:5.9:69:3500 200ºC 24h
F 1 100:5.9:69:3500 200ºC 24h
41