Explain Rosenmund reduction

Explanation

Aldehydes can be preapared by the hydrogenation of acid chloric in the presence of palladium supported by Barium sulphate. This reaction is called Rosenmund reduction
`CH_(3) - underset(O)underset(||)(C ) - CI + H_(2) overset(Pd//BaSO_(4))(to) CH_(3) - underset(O)underset(||)(C )- H + HCI`
In the above reaction `BaSO_(4)` act as catalytic poison to palladium catalyst so that aldeyde cannot be further reduced to alcohol.