Six zeolite samples were studied simultaneously with the help of the ASAP 2420 equipped with the Micropore option. The Micropore option helps conducting micropore analysis on all six ports simultaneously, comparable to the High Throughput mode. These analyses were conducted using Argon, as the adsorptive substance, at 87 K. Standard micropore analysis using nitrogen may take as long as five to seven days. By using Argon, the analysis can be reduced down to two days.
The following samples were used in the analysis, they are listed in the table below:
Table 1. Samples used for analysis.
||SiO2 / Al2O3
The step-by-step sample preparation was as follows:
- Initially, the samples were prepared on the degas ports using the automated degas control.
- All samples were heated to a temperature of 400 °C at 10 °C per minute and held at that temperature for 2 hours.
- Next, the samples were placed on the analysis ports, where they were manually degassed at a temperature of 200 °C for 1 hour with the help of lace-up heating mantles.
- Between the two degas procedures, each tube was weighed and the sample mass was determined.
The step-by-step sample analysis was conducted as follows:
- The micropore analyses were conducted with the low pressure dosing option, and each sample tube was provided with an isothermal jacket and seal frit.
- The Dewars were initially filled to a satisfactory level as determined by the depth gauge.
- After the analyses were completed, the Dewars were refilled to a comparable level and a second series of single-point analyses was performed to determine the free space.
- A full isotherm was also obtained for each sample (see Figures 1 and 2).
Figure 1. The ASAP2420 with Micropore option.
The linear and logarithm isotherm plots are shown in Figures 2 and 3. Results from the analyses feature an interesting and partially expected trend. The H-Y samples align very closely, as seen on the isotherm log plot.
Figure 2. Isotherm with linear pressure axis.
Figure 3. The same data as shown in Figure 2 with the pressure in log scale.
Interestingly, the H-β samples behaved differently from each other. The ZSM-5 showed a distinct shape, which is expected considering it belongs to a different class of zeolites.
As highlighted in Figure 4, the Horvath-Kawazoe differential plots provide the Saito-Foley cylinder pore volume.
Figure 4. The Horvath-Kawazoe pore volume distribution.
This information has been sourced, reviewed and adapted from materials provided by Micromeritics Instrument Corporation.
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