Recovery of the polymers formed during thermal cracking of N-substituted dicarbamates over Fe–Ni/Al2O3

The thermal cracking behavior of diethyl hexamethylenedicarbamate (EHDC) was investigated in this work. The polymers formed under different conditions were analyzed by IR and TG, indicating that the polymers were mixtures of EHDC, polyureas, imines and others. The polymers could be converted to EHDC by a simple alcoholysis reaction for the first time over Fe–Ni/Al2O3 catalysts. Under the optimized reaction conditions, the yield of EHDC could reach up to 52% with 99% selectivity over 8% Fe–3% Ni/Al2O3 catalysts. The catalysts were extensively characterized by BET, XPS, XRD, SEM, TEM, H2-TPR and NH3-TPD, showing that the interaction effect between Fe species and Ni species may be attributed to high catalytic performance of the catalyst. Meanwhile, the loss of active components resulted in decreased catalytic activity.