Based on the answer and the topic 'Acid Derivatives', the reaction corresponds to the Rosenmund Reduction. In this reaction, an acid chloride ($RCOCl$) is hydrogenated over a catalyst of palladium supported on barium sulphate ($Pd/BaSO_4$). This specific catalyst system (poisoned with sulphur or quinoline) allows the reduction to stop at the aldehyde ($RCHO$) stage, preventing further reduction to a primary alcohol ($RCH_2OH$).

$RCOCl + H_2 \xrightarrow{Pd/BaSO_4} RCHO + HCl$