the production of thymoquinone from thymol and carvacrol

7.1.5. Pore Volume and Surface Area Measurement
The specific surface areas of the adsorbents can be determined by applying the
Langmuir model equation for Type I isotherm. Nitrogen physisorption isotherms of
NaY zeolite, Cr NaY and Cr (salpn)-NaY were obtained. They were Type I isotherms
according to IUPAC classification. The micropore volume and size reduced apparently
after modification also indicated that the metal complex was successfully introduced
into the inner channels of Cr based catalyst. The results were summarized in detail in
Table 7.3.
Table 7.3. Surface area and micropore volume analysis
Materials Langmuir surface
area
(m 2 /g)
Micropore volume
(cm 3 /g)
(from Horvath-Kawazoe)
NaY zeolite 807 0.34
Cr NaY 801 0.27
Cr(salpn)-NaY 536 0.22
Surface areas were found to be between 536 and 807 m 2 /g as seen in Table 7.3.
The Horvath-Kawazoe method can be applied for a quantitative determination of the
micropore volume. In the literature, it was frequently reported that the lowering the pore
volume and surface area was the indication the metal complexes were present within the
zeolite cages (Varkey et al. 1998, Joseph et al. 2002).
7.1.6. Thermal Analyses
7.1.6.1. Differential Scanning Calorimetric Analysis of Ligand
The melting point of ligand (H2 salpn) was found by differential scanning
calorimetric analysis (DSC). Melting point of ligand was found as 53 ºC
( H = − 73.54 kJ/kg ) by differential scanning calorimetric (DSC) analysis as seen in
47