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

4 Results and discussion
900 [ºC]
700 [ºC]
Calcination temp.
Time
5 hours
65
200 MPa
Pressure
50 MPa
10 MPa
Figure 36 The HIP calcination program. Solid lines present the temperature profile and the dashed lines the
applied pressure of technical air
Table 19 Crystallinity loss and cage occupancy of Hot Isostatic Pressure calcined D1H samples. All the
HIP calcinations were performed for 5 hours with heating and cooling ramps of 10ºC/min.
Temperature Pressure Crystallinity loss Cage occupancy
As made - 75 - 78%
700ºC/5h - Ca. 14% 67%
700ºC/5h 10x10 MPa Ca. 1% 15%
900ºC-21 Days - Ca. 13% 11%
900ºC/5h - Ca. 9% 64%
900ºC/5h 2x50 MPa Ca. 13% 1%
900ºC/5h 200 MPa Ca. 23% -
Increasing the temperature and pressure to 900ºC and 200 MPa for 5 hours resulted in
significant crystallinity loss (Table 19). The air pressure of 200 MPa might have been
sufficient to destroy the D1H crystals partly.
Decreasing the pressure to 50 MPa and applying this pressure twice at 900ºC for 5 hours
resulted in very low carbon content and maintaining the high crystallinity (Figure 37).
HIP calcination using a pressure cycle of 50 MPa on templated D1H crystals results in
quasi-SDA free D1H. Again, a peak intensity increase is observed in the low angle scale
indicating free (or nearly free) zeolitic pores (Table 19). All the samples used in this HIP
calcination are in the range of 5-40 µm.
The results suggest that the gas transport of penetrating oxygen and combusted gasses is
enhanced by the pressure swing process at elevated temperatures. This quasi SDA-free
D1H is a potential membrane material with a well defined pore size of 2.8 Å and might