Temperature control of exothermic reactions

In a selective hydrogenation process wherein at least two catalyst beds in series are utilized, the temperature of the feed stream to the first catalyst bed and the temperature of the feed stream from the first catalyst bed to the second catalyst bed are manipulated so as to maintain a desired reaction temperature in both catalyst beds. The desired reaction temperature of the first catalyst bed is manipulated so as to insure that a desired percent of a specific feed component is selectively hydrogenated in the first catalyst bed. The reaction temperature of the second catalyst bed is manipulated so as to maintain a desired concentration of the specific feed component in the product stream from the second catalyst bed.