Regio-selective catalytic vapor phase alkylation of aniline: preparation of 2,6-diethylaniline Original Research Article

Catalytic vapor phase alkylation of aniline using ethyl alcohol to manufacture 2,6-diethylaniline (2,6-DEA) has been achieved in the presence of attapulgite clay impregnated with iron oxide as catalyst and tin oxide as promoter at atmospheric pressure and at a temperature in the range of 330–440 °C. Investigations were carried out for selective alkylation using attapulgite impregnated with various compositions of iron oxide and promoters. Conversions of 75–80% with 74% selectivity towards 2,6-diethylaniline have been achieved with a combination of 60% iron oxide and 2% tin oxide impregnated on attapulgite while 15% iron oxide and 1% germanium dioxide gave N-ethylaniline (MEA) with 80% selectivity. At lower W/F ratios (weight of catalyst charged/feed rate, g/(h mol)), selectivity of the catalyst towards N- or C-alkylation was not significantly affected by temperature, but at higher W/F ratios increase in temperature caused a decrease in selectivity. At higher temperatures, rearrangement of alkyl groups and extensive disproportionation were observed. Increasing the mole ratio of ethanol to aniline increased the conversion as well as the selectivity, but the conversions decreased with temperatures above 390 °C due to ethanol degradation.