, have a relatively good performance [50,51]. The selectivity to MAA plus methacroleine reaches more than 70%. But, when isobutane conversion is increased, the selectivity falls fairly linear. This is because the consecutive oxidation rate of the produced MAA is much larger than the rate of isobutane conversion. Though the conversion is around 10%, a comparatively high productivity can be attained. Table 1 shows the productivity enhancement by increasing pressure and space velocity [52]. For industrialization, a short catalyst life would be a big problem, and a development of high performance catalyst would be a key factor.