BEHAVIOR OF SILVER-THORIUM PHOSPHATE AGTH2(PO4)(3) IN BUTAN-2-OL CONVERSION

Catalytic conversion of butan-2-ol was studied over silver-thorium pho sphate AgTh2(PO4)(3). Its selectivity was found to be mainly oriented towards the oxide hydrogenation reaction when oxygen was added to the reaction mixture. This activity was interpreted as reflecting the Agions mobility in the conduction tunnels of the phosphate framework. Un der reaction conditions, butan-2-ol reduces the silver cations. The en suing crystallites, in presence of O-2 form Ag-x-O-y species which are active in the production of methyl ethyl ketone. Concurrently, the Ag + ions are replaced by protons released by the alcohol, without any de tectable modification of the structure. The influence of their acidity on the dehydration reaction was very Limited. Similar results were ac hieved by using hydrogen as agent for Ag+ reduction. Physical techniqu es were used to characterize the phosphate before and after the cataly tic tests and to support this results: (i) XRD, XPS, TEM and EDX-STEM showed the formation of silver crystallites with an average size of 10 nm, well dispersed on the sample; (ii) UV-visible spectroscopy confir med the nucleation of the silver particles; (iii) H-1 MMR MAS establis hed that new protons bonded to [PO4] groups appear in the sample.