Patent ID: 7253309
Filing Date: 2007-08-07
Classification: B01J,C07C

Abstract:
1. A method for the production of methacrylic acid by the use of a shell-and-tube type reactor incorporating built-in reaction tubes packed with a heteropoly-acid catalyst and circulating a heat medium as a fluid outside the reaction tubes, said method comprises dehumidifying and heating air prior to introduction to said catalyst, introducing said preheated and dehumidified air into catalyst beds to maintain the relative humidity of the catalyst beds in the range of not more than 40% while elevating the temperature of said reactor thereby starting up the reactor, and preventing the catalyst from absorbing moisture and, introducing a gas containing at least one compound selected from the group consisting of methacrolein, isobutyl aldehyde, isobutyric acid, and isobutene to said catalyst beds to oxidize and/or oxidodehydrogenate at least one compound selected from said group consisting of methacrolein, isobutyl aldehyde, isobutyric acid, and isobutene in a gas phase with molecular oxygen or a molecular oxygen-containing gas thereby obtaining said methacrylic acid.