Multitube reactor, vapor phase catalytic oxidation method using the multitube reactor, and start up method applied to the multitube reactor

A vapor phase catalytic oxidation method comprising:

• providing a multitube reactor comprising a plurality of reaction tubes having a catalyst packed therein, and a shell equipped with the reaction tubes inside and into which a heat medium flowing outside the reaction tubes is introduced, wherein the reaction tubes are selected from tubes having same nominal outside diameter and same nominal wall-thickness, an outside diameter tolerance of ±0.56%, and a wall-thickness tolerance of +17% to −0%, which further comprises baffles connected to the reaction tubes through connecting sites for changing a flow path of a heat medium introduced into the shell;
• circulating the heat medium through the outside of the reaction tubes;
• and feeding a reaction raw material gas inside the reaction tubes packed with a catalyst to obtain reaction product gas;
• wherein the method comprises setting catalyst packing specifications in the reaction tubes so that catalyst layer peak temperature sites of the reaction tubes are not located at the connecting sites between the baffles and the reaction tubes.

A vapor phase catalytic oxidation method comprises:

• using a multitube reactor which comprises:
• a cylindrical shell having a raw material feed port and a product discharging port;
• a plurality of ring-shaped tubes arranged on an outer periphery of the cylindrical shell for introducing or discharging a heat medium into or from the cylindrical shell;
• a circulating device connecting the plurality of the ring-shaped tubes one another;
• a plurality of reaction tubes restrained by a plurality of tube plates of the reactor and comprising a catalyst;
• and a plurality of baffles provided in a longitudinal direction of the reactor and for changing a direction of the heat medium introduced into the cylindrical shell;
• oxidizing propylene, propane, or isobutylene, and/or (meth)acrolein through vapor phase catalytic oxidation with a molecular oxygen-containing gas to obtain (meth)acrolein and/or (meth)acrylic acid,;
• wherein the method comprises,
• packing a Mo—Bi catalyst and/or Sb—MO catalyst in the reaction tubes so that anactivity increases from a process gas inlet to a process gas outlet of the reaction tubes;
• and
• allowing the heat medium and the process gas to flow in a countercurrent.