Process for producing (meth)acrolein or (meth)acrylic acid

A process for producing (meth)acrolein or (meth)acrylic acid, comprising:

• feeding a raw material of the (meth)acrolein or (meth)acrylic acid, and a molecular oxygen-containing gas mixed with a diluting gas and compressed by a compressor, to an oxidation reactor to conduct a catalytic gas-phase oxidation reaction therebetween;
• feeding the obtained reaction gas to an absorption column to contact with water;
• recovering an aqueous solution of the (meth)acrolein or (meth)acrylic acid from a bottom of the absorption column, and an exhaust gas from a top of the absorption column;
• and
• recycling a part or whole of the thus recovered exhaust gas to use the gas as the diluting gas,
• wherein the diluting gas and the molecular oxygen-containing gas are mixed with each other using a mixer, a residence time of the mixed gas from mixing of the diluting gas with the molecular oxygen-containing gas to introduction into the compressor is not less than 0.3 second, and a temperature of a mixed gas containing the molecular oxygen-containing gas and the diluting gas at a suction inlet of the compressor is in the range of 35 to 70° C.