Effect of modified alumina support on the active surface of aluminum-nickel-molybdenum catalysts for conversion of ethylene to propylene

Ni, Mo-containing oxide catalysts synthesized using cation- and anion-modified aluminum oxide (Na 2 O-Al 2 O 3 , MgO-Al 2 O 3 , Al 2 O 3 -Al 2 O 3 , ZrO 2 -Al 2 O 3 , B 2 O 3 -Al 2 O 3 , SO 4 2- -Al 2 O 3 ) as a support have been studied. The modification effect of the support surface on the physicochemical properties and catalysts activity in the process of conversion ethylene to propylene has been established. Anionic modification (B 2 O 3 -Al 2 O 3 , SO 4 2- -Al 2 O 3 ) promotes an increase in the activity of catalysts, which is due to the formation of octahedrally coordinated Ni 2+ ions bound to the acidic sites of the support surface. In contrast, cationic modification (Na 2 O-Al 2 O 3 , MgO-Al 2 O 3 , Al 2 O 3 -Al 2 O 3 , ZrO 2 -Al 2 O 3 ) suppresses the development of ethylene conversion reactions. The maximum propylene yield of 51-52 wt.% is provided by catalysts based on a borate-containing support and unmodified alumina. They are distinguished by the presence of surface highly dispersed polymolybdate species and medium-strength Brønsted acid sites.