Page 346 - Adsorbents fundamentals and applications

OLEFIN/PARAFFIN SEPARATIONS 331

2.0

1.5

Q (m mol/g) 1.0 C 3 H 6 : 343 K

H : 393 K
C 3 6
H : 343 K
C 3 8
C H : 393 K
0.5 3 8

0.0
0 1 2 3 4 5 6
P (atm)
Figure 10.36. Adsorption isotherms of C 3 H 6 and C 3 H 8 on AlPO 4 -14 sorbent at 343 K and
393 K (Rege and Yang, 2002, with permission).

Table 10.9. Operating parameters and performance results for separation of a mixture
composed of 85% C 3 H 6 and 15% C 3 H 8 by PSA using AgNO 3 /SiO 2 and AlPO 4 -14 sorbents
Run No. P L U F U P C 3 H 6 C 3 H 6 C 3 H 6 Product
(atm) (m/s) (m/s) Product Product Throughput (kg
Purity (%) Recovery (%) Product/h/kg
of Sorbent) × 10 3
AgNO /SiO 2
3
1 1.0 0.40 0.30 99.33 42.99 3.56
2 1.0 0.10 0.30 99.14 59.60 3.45
3 0.2 0.40 0.30 99.17 54.51 7.95
4 0.2 0.01 0.35 99.24 75.11 6.54
AlPO 4 -14
5 1.0 0.50 0.25 99.34 37.69 3.77
6 1.0 0.05 0.30 99.27 65.16 2.00
7 0.2 0.25 0.20 99.29 56.88 6.14
8 0.2 0.10 0.20 99.18 72.33 6.07
◦
Feed pressure P H = 7.0 atm., step time = 60 s, feed T = 120 C, P L = des. press., U F = feed velo.,
U P = purge velo. (Rege and Yang, 2002, with permission).

2
◦
constants (D/R )for C 3 H 6 and C 3 H 8 at 120 C for both sorbents were >10 −3
1/s, and the diffusion rates did not play an important role in the separation.
The results of the PSA simulations for the four-step cycle described above for
the AlPO 4 -14 and AgNO /SiO 2 sorbents with a feed composed of 85% C 3 H 6
3
◦
and 15% C 3 H 8 at a temperature of 120 C are summarized in Table 10.9. The