Catalytic Activity of Rhodium Complexes Supported on Al2O3–ZrO2in Isomerization and Hydroformylation of 1-Hexene

Abstract

Two new nanostructured Al2O3–ZrO2 mixed oxides supports, A and B, have been prepared by sol–gel process and characterized by TEM, XRD and XPS methods. The freeze-dried gel gave support A whereas the support B was obtained by drying of gel at ambient temperature. Both supports reacted with Rh(acac)(CO)2 complex, producing Rh(CO)2 + tethered species, characterized by ν(CO) at 2011 and 2083 cm−1. The Rh(CO)2 +/A applied as catalyst for reaction of 1-hexene at 80 °C with H2/CO = 1, at 10 atm was found as active for isomerization (ca. 90% of 2-hexene after 6 h) and relatively poor catalyst of hydroformylation (<10% of aldehydes). At the presence of stoichiometric amount of PPh3 the yield of aldehydes increased up to 65%. The selectivity of the reaction was strongly dependent on the catalyst pre-treatment with CO or CO/H2 mixture.