Effect of Support Treatment with Modifiers, (NH4)2SiF6 and H3BO3, on the Catalytic Properties of Mo/Al2O3 in Propylene Metathesis

Supported catalysts Mo/Al 2 O 3 in which the support was modified with additions of (NH 4 ) 2 SiF 6 and H 3 BO 3 were synthesized and tested in metathesis of propylene to ethylene and butylenes. The samples obtained were studied by low-temperature nitrogen adsorption–desorption, X-ray fluorescence analysis, energy-dispersive X-ray analysis, temperature-programmed NH 3 desorption, and in situ Raman spectroscopy. The support modification with (NH 4 ) 2 SiF 6 does not alter the acid properties of the final catalyst, whereas the interaction of γ-Al 2 O 3 with boric acid leads to an increase in the total acidity of the final catalyst. Modification of the support both with (NH 4 ) 2 SiF 6 and with H 3 BO 3 appreciably enhances the catalyst activity but favors its faster deactivation.