Synthesis and catalytic behaviour of heterogenized rhodium catalysts on modified clays Original Research Article

Rhodium catalysts were synthesised by hydrogen reduction at atmospheric pressure of a cationic organometallic rhodium complex (using [Rh(Me2CO)x(NBD)]ClO4 as the metal precursor species, in which (NBD) is 2,5-norbornadiene and (Me2CO)x is acetone) and anchored onto modified clays: laminar and zeolitic products. The zeolitic products were synthesised under different treatment conditions and in different media, distilled water and seawater; the laminar products consisted of one pillared clay sample and homogenised montmorillonite. The rhodium catalysts were applied in the transformation of acetone. The reaction was carried out at atmospheric pressure and low temperature, after activation at different temperatures. Activity, selectivity and durability depend on the nature of the support used in the preparation of the catalyst. The acidic centres of the pillared montmorillonite favored the formation of methyl isobutyl ketone (MIBK), whereas the other heterogeneous catalysts favored greater selectivity towards isopropanol (IPA). Except the homogenised montmorillonite, the products used as supports in the heterogeneous catalysts showed catalytic activity, although much lower than those prepared by anchoring rhodium on them.