Patent ID: 7238836

Claim:
In a process of producing unsaturated aldehydes and unsaturated acids from olefins by fixed-bed catalytic partial oxidation in a shell-and-tube heat exchanger-type reactor, the reactor comprising one or more catalytic tubes each including a first-step reaction zone of mainly producing the unsaturated aldehydes, a second-step reaction zone of mainly producing the unsaturated acids, or both the two zones, the improvement wherein: the first-step reaction zone is divided into two or more zones by a partition, each of the divided shell spaces being filled with a heat transfer medium, the heat transfer medium being maintained at isothermal temperature or a temperature difference of 0–5° C., in which the temperatures of the heat transfer medium in each of the divided shell spaces are set to increase in the moving direction of reactants, and when the shell spaces divided by the partition in the first-step reaction zone are named, such as zone 1, zone 2, zone 3, . . . , T h1 −T salt1 is ≦150° C. and T hN −T saltN is ≦120° C., wherein N is an integer of 2 or more, T h1 is the peak temperature of a reaction mixture in a catalyst layer corresponding to the first shell space (the peak temperature of the catalyst layer), T hN is the peak temperature of a reaction mixture in a catalyst layer corresponding to the Nth shell space (the peak temperature of the catalyst layer), T salt1 is the temperature of a heat transfer medium filled in the first shell space, and T saltN is the temperature of a heat transfer medium filled in the Nth shell space.