Article Abstract:
The reactivity and unique properties of the titanium silicalite TS-1 were investigated using calorimetric and adsorption methods. Experimental results showed the absence of the strong acid site found in HZSM-5 and the presence of only 0.07 mmol g(super -) of a -15.1 kcal mol(super -1) hydrogen-bonding site. Titrations with 2,6-lutidine revealed the same number of hydrogen-bonding sites with a lower enthalpy. The magnitude of these enthalpies suggests that the acceptor sites are hydrogen-bonding sites that are comparable in acidity to the strongest sites on silica gel. In addition, the porosity and small number of hydrogen-bonding sites allow TS-1 to adsorb hydrocarbons in the presence of water.
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Article Abstract:
The properties of the Ti-beta zeolite synthesized by the dry-gel conversion method (Ti-beta-DGC) were investigated in comparison with the Ti-beta synthesized by the hydrothermal method (T-beta-HTS). Results showed that Ti-beta-DGC samples adsorbed less water than T-beta-HTS, which suggests that the former is more hydrophobic than the latter. It is proposed that this leads to a higher activity for Ti-beta-DGC in the oxidation of cyclohexane, which is interpreted in terms of high hydrophobicity of Ti-beta-DGC compared to that of Ti-beta-HTS..
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Article Abstract:
Research was conducted to examine the intrinsic catalytic cracking activity of hexane over H-ZSM-5, H-beta and H-Y zeolites. Catalytic results were calculated at temperatures up to 623 K and the hydrogen form of the zeolites was utilized at low temperature to avoid cracking. The reaction of the hydrogen forms to adsorption were extrapolated to the reaction temperature using heats of adsorption. Results indicate that the intrinsic activity for mono- and bimolecular n-hexane cracking over the zeolites is largest for H-ZSM-5.
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