Titanium incorporated ATS and AFI type aluminophosphate molecular sieves

Abstract

Titanium aluminophosphate molecular sieves of ATS and AFI (with two different titanium levels in the framework) have been synthesized. These materials were characterized using XRD, SEM, BET, Al-27 and P-31 MAS NMR, XPS and EXAFS techniques. The results of XRD, SEM, BET and Al-27 and P-31 MAS NMR indicated the highly crystalline nature and phase purity of the samples. All these materials show a significant pre-edge peak at 4968 eV for Ti, characteristic of tetrahedral Ti. The average Ti-O coordination number for the ATS and AFI titanium aluminophosphates is 4.4 +/- 0.3. XAFS obtained at the Ti K edge indicated the Ti incorporation in the ATS and AFI AlPO frameworks. In the ATS aluminophosphate, Mg and Ti are present in the framework. The catalytic performance of the ATS and AFI titanium aluminophosphate catalysts were investigated in the conversion of cyclohexanol to cyclohexanone with hydrogen peroxide in the presence of acetone at 353 K. The catalytic activity of these molecular sieves are compared with that of the titanium silicalite-1 zeolite.