| Methacrylic Acid (MAA) is one of the most important organic materials, and there is large demand indomestic and international market. The traditional preparation method of MAA has lots of limitation suchas high cost, huge pollution, and virulent raw materials. So it's necessary to search a new green route toreplace the ACH route. And later the oxidation of isobutene to MAA via methylacrolein (MAL), andmethylation of propylene (or ethylene) are developed. However, these processes exist many disadvantagessuch as high cost of raw materials and multistep reactions et al. Due to the process for selective oxidationof n-butane to maleic anhydride has been industrialized. People move their line of sight to the morepreponderant one-step oxidation of light alkanes, hope receiving MAA from isobutane directly.Several catalytic systems have been reported for the direct oxidation of isobutane. Among them, P-Moheteropoly compounds (HPC) with Keggin-type structure exhibited relative high catalytic performance.In this research, various types of P-Mo-Fe-K-(NH4)+ heteropolyacid catalyst supported on SiO2 wereprepared. The influence of factors such as chemical composition, preparation methods and reactionconditions on the activity of catalyst was investigated in detail to find a better performance catalyst and thesuitable reaction condition. And the catalysts structure is characterized by IR, XRD, BET.The results show that the primary structure of the catalyst is Keggin-type structure and there isdifference in the second structure of the catalyst with the different chemical composition. The catalystK1Fe0.3(NH4)2PMo12O40 supported on SiO2 has a high activity for oxidation of isobutanc to MAA with aconversion of 11.2％for isobutane, a selectivity of 46.7％for MAA, a yield of 5.23％for MAA. While thereaction condition is controlled at 360℃with reactants proportion as i-C40:O2:H2O:N2=26:13:12:49, spacevelocity(SV)=1000h-1 and time on stream(tos)=70hs.
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