Patent ID: 7731919

Claim:
A fixed bed reactor for gas-phase catalytic oxidation, the fixed bed reactor comprising a reaction tube filled with a gas-phase oxidation catalyst for producing acrolein by gas-phase catalytic oxidation of propylene with molecular oxygen, wherein a solid acid is placed in an end portion(s) of the reaction tube or between catalyst layers of the catalyst, or mixed in the catalyst, the solid acid is an oxide or a complex oxide containing at least one kind of element selected from the group consisting of aluminum (Al), silicon (Si), titanium (Ti) and zirconium (Zr), and has a shape of sphere, cylindrical column, cylindrical tube, star, ring, tablet or pellet, the catalyst is a complex oxide containing molybdenum (Mo) and bismuth (Bi), and acid strength (H 0 ) of the solid acid meets an inequality: −5.6≦H 0 ≦1.5.