The thermal frequency response technique was used to study the diffusion of benzene in NaX zeolite. The corrected diffusion coefficient was found to be independent of loading of between 1.5 and 3.6mol/cage at 406K (table 50). It was in reasonable agreement with pulsed-field gradient NMR or quasi-elastic neutron scattering methods, but a large discrepancy was observed with regard to tracer zero length column technique results. The activation energy (27kJ/mol) for diffusion, determined using thermal frequency response methods, was in accord with the tracer zero length column value, but was substantially higher than the values obtained using other techniques.

Diffusion of Benzene in NaX Zeolite, Studied by Thermal Frequency Response. A.Malka-Edery, P.Grenier: Journal of Physical Chemistry B, 2001, 105[29], 6853–7

 

Table 50

Diffusivity of Benzene in NaX Zeolite

 

Pressure(Pa)

T(C)

Loading(mol/cage)

D(m2/s)

5.8

373

2.9

4.0 x 10-10

4.9

406

1.6

2.5 x 10-10

13.2

406

2.3

2.8 x 10-10

48.2

406

3.0

8.5 x 10-10

55.2

353

4.0

2.6 x 10-10

5.78

337.3

3.8

3.5 x 10-10

15.17

337.2

4.0

2.1 x 10-10

67.45

353.0

4.0

1.7 x 10-10

135.1

373.5

3.9

5.3 x 10-10

238.5

392.2

3.8

8.0 x 10-10

334.0

413.3

3.6

1.1 x 10-9

201.0

403.7

3.6

1.3 x 10-9

118.3

392.8

3.6

6.5 x 10-10

389.8

412.7

3.6

1.1 x 10-9