the production of thymoquinone from thymol and carvacrol
the production of thymoquinone from thymol and carvacrol
the production of thymoquinone from thymol and carvacrol
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Two stages <strong>of</strong> weight losses were observed for Cr (salpn)-NaY catalyst up to<br />
510 ºC. The weight losses <strong>of</strong> %14.8 in <strong>the</strong> temperature range 30-258 ºC corresponds to<br />
<strong>the</strong> physically adsorbed <strong>and</strong> chemisorbed (in <strong>the</strong> form <strong>of</strong> OH groups) intra-zeolite water<br />
in <strong>the</strong> zeolite channels <strong>and</strong> cavities as well as <strong>the</strong> water coordinated to Cr (salpn)<br />
complex. O<strong>the</strong>r stage <strong>of</strong> smaller weight losses (% 9.7) in <strong>the</strong> temperature range 260-470<br />
ºC was observed. This loss occurs in <strong>the</strong> wide temperature range <strong>and</strong> it was due to <strong>the</strong><br />
slow decomposition <strong>of</strong> lig<strong>and</strong>. A smaller weight percentage loss indicates <strong>the</strong> insertion<br />
<strong>of</strong> only small amount <strong>of</strong> metal complexes in <strong>the</strong> zeolite NaY cavities (Maurya et al.<br />
2002a). This was an agreement with low percentage <strong>of</strong> metal content estimated by<br />
inductively coupled plasma (ICP) technique.<br />
Both TGA <strong>and</strong> pore volume <strong>and</strong> surface area measurements techniques<br />
supported encapsulation <strong>of</strong> Cr (salpn) complex.<br />
Figure 7.7. TGA (a) <strong>and</strong> DT/TGA (b) curves <strong>of</strong> <strong>the</strong> NaY, CrNaY <strong>and</strong> Cr (salpn)-NaY<br />
catalyst<br />
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