CATALYTIC PARTIAL OXIDATION OF PROPANE TO ACROLEIN

Results are discussed on the direct oxidation of propane to acrolein o n Me(x)O(y)-supported Ag0.01Bi0.85V0.54Mo0.45Ox (Me(x)O(y) = gamma-Al2 O3, TiO2, SiO2) and on Me(7)Bi(5)Mo(12)O(x) (Me = Mg, Ca, Zn) catalyst s. Almost no formation of acrolein was observed over Me(x)O(y)-support ed catalysts although active phases for oxidative dehydrogenation of p ropane (dispersed y VOx species) and oxygen insertion in propene (sche elite structure) were present. For Me-Bi-Mo-O, selectivities to acrole in and CO, depended on the nature of the third cation and reaction mix ture used. The acrolein selectivities amounted to 34 and 20% (yields o f 3.2 and 2.7%) when using Ca(7)Bi(5)Wo(12)O(x) and Mg7Bi5Mo12Ox, resp ectively. Redox properties were found to be an important factor determ ining the reaction pathways. Tentatively it can be concluded that diff erent types of lattice oxygen are involved in propane dehydrogenation to propene and consecutive reactions towards acrolein and COx. Under c onditions of effective propane dehydrogenation to propene a competitiv e reaction between an allylic intermediate and propane forming propene and propyl radical can be assumed as the reason for low acrolein form ation in favour to propene. Applying a two layer fixed bed reactor an acrolein yield of 7.4% (S = 20%) was obtained.