Synthesis of methylamines from CO2, H2 and NH3. Catalytic behaviour of various metal-alumina catalysts Original Research Article

The synthesis of methylamines from CO2, H2 and NH3 has been investigated over various metal-alumina catalysts (Cu, Ag, Ni, Pt, Co and Fe) prepared by coprecipitation. Catalytic tests were carried out using a fixed-bed reactor in the temperature range 473–573 K and at 0.6 MPa total pressure. Among all metal catalysts highest methylamine production rates were obtained with the copper-alumina catalysts, affording a distribution of monomethylamine (MMA): dimethylamine (DMA): trimethylamine (TMA) of 72 : 15 : 13 at 513 K. Increasing the ammonia concentration in the feed resulted in improved selectivity to MMA. By-products observed over copper-alumina were carbon monoxide, originating from the reverse water gas shift reaction, and water. Ni, Co, Fe and Pt showed little methylamine production, but significant methane formation, whereas Ag produced only CO, H2O and HCN.