Patent ID: 7176335

Claim:
A process for preparing methacrolein from isobutane comprising A) subjecting isobutane in a reaction zone A to a partial heterogeneously catalyzed dehydrogenation in the gas phase to form a product gas mixture A which comprises isobutene and unconverted isobutane, B) passing product gas mixture A into a reaction zone B and subjecting the isobutene in the reaction zone B to a heterogeneously catalyzed partial oxidation in the gas phase with molecular oxygen to form a product gas mixture B which comprises methacrolein, and C) optionally, further reacting the methacrolein in the product gas mixture B and optionally recycling isobutane in the product gas mixture B into reaction zone A, wherein the molecular oxygen is added to reaction zone B with molecular nitrogen in a molar ratio of molecular oxygen to molecular nitrogen of from 1:1 to 1:10.