Methylation of aniline over a mildly acidic siliconaluminium phosphate catalyst (SAPO-11) with medium pores is reported. The selectivity of N-methylates products is about 90%. By comparison with results obtained from SAPO-5 with large pores and with amorphous aluminium phosphate, molecular sieves with medium pores prevent the formation of bulky isomers and better resist formation of coke. The ortho isomer is most abundant among toluidine isomers. Some ortho isomers may result from the rearrangement of N-methylaniline.
