Isobutyraldehyde is formed In excess in propane hydroformylation (oxo synthesis). Isobutyraldehyde, H2O 1.5%, was ketonized over of a 0.6-1.2-mm Zr-Mg-Y-O catalyst bed, 3 cm(3), load 1 h(-1), at 380-480degreesC to yield 48% (440degreesC) of diiso-Pr ketone and 21 % of other compounds. At 440degreesC, (1:1) Isobutyraldehyde -n-BuOH gave di-Pr 26, Pr-i-Pr 21 and diiso-Pr ketone 9% and 24% of other compounds. 35 refs.