I've read articles online and they rarely mention about chlorination of benzaldehyde but more on bromination. Also, I would like to know the catalyst used for this is FeCl3 or AlCl3? Thanks for your help!:)
The experimental process of chlorination of benzaldehyde to form benzoyl chloride can be found here:
A round bottom flask is fitted with a reflux condenser and a gas inlet tube. 100 grams of cold and dry benzaldehyde are added to the flask and saturated with the current of dry chlorine. The chlorine gas is readily absorbed and the evolution hydrogen chloride takes place. When the reaction has moderated, the external heat is applied by keeping gentle boiling. The stream of chlorine is continued until no more hydrogen chloride is evolved. A stream of dry air or carbon dioxide is then passed through the apparatus in order to remove an excess of chlorine. Benzoyl chloride is obtained by distillation as a colorless fuming liquid with a very irritating smell. Yield almost quantitative.
Preparation of organic compounds, E. de. Barry Barnett, 52, 1912
There is also a German paper written by Freidrich Wohler and Justus von Leibig which mentions an early preparation of benzoyl chloride by the action of chlorine over benzaldehyde.