Thermo regulated phase-separable Ir nano catalyst was applied to the selective hydrogenation of α

β-unsaturated aldehydes and ketones and its catalytic hydrogenation performance was systematically investigated. Under the optimized reaction conditions

the Ir nano catalyst exhibited high selectivity of C═O bond for α

β-unsaturated aldehydes (>99%)

while high selectivity of C═C bond for α

β-unsaturatedketones (>99%). The catalyst can be simply separated and directly reused for 5 times with the selectivity remaining >99%. Furthermore

the results of TEM showed that the particle size of Ir nano catalyst after four cycles was (1.9 ± 0.2) nm

which increased a little compared with the Ir nano catalyst newly prepared. The results of ICP-AES showed that the leaching of Ir in the upper organic phase was below the detection limit (the detection limit is 5 μg/L).