Patent ID: 6966973

Claim:
An apparatus for producing (meth) acrylic acid by catalytic gas phase oxidation, with said apparatus being selected from the group consisting of a reactor, an absorber, a stripping column, an extraction column, a distillation column, their fittings including heat exchangers, and reboilers off distillation columns, wherein said apparatus comprises a part that comes into contact with (meth)acrylic acid, and wherein said part comprises: (A) an alloy (A) comprising nickel, chromium and iron, with said alloy (A) having a molybdenum content of more than 3 mass % and not more than 20 mass %, with said alloy (A) minimizing polymerization of (meth)acrylic acid during production of (meth)acrylic acid; or (B) an alloy (B) comprising nickel, chromium and iron, with said alloy (B) having a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %, with said alloy (B) minimizing polymerization of (meth)acrylic acid during production of (meth)acrylic acid.