Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Abstract

A novel method for the synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn_30.1Cr_4.3/γ-Al₂O₃ was established. A yield as high as 87.9% was received when the reaction was conducted on a fixed-bed reactor dosed with 30 ml (21 g) catalyst at 693 K under ammonia at atmospheric pressure by keeping the liquid velocity of styrene epoxide diluted with toluene (styrene oxide : toluene = 20 : 80 (m : m)) at 0.2 ml min⁻¹ and the gas velocity of ammonia at 300 ml min⁻¹. The lifetime of the catalyst was evaluated and the activity of the catalyst could be recovered by continuously blowing air into the fixed-bed at 723 K for 3.5 h online. The catalyst was characterized by XRD, XPS, TEM and IR of adsorbed pyridine. The characterization results indicated that the dehydration reaction in the tandem reaction mainly took place on the Lewis acid sites and revealed that ZnAl₂O₄ is the active species for the dehydrogenation of imine to nitrile. The doping of chromium on to the γ-Al₂O₃ supported zinc catalyst Zn_29.9/γ-Al₂O₃ could diminish the size of ZnAl₂O₄ crystallites, which is in favor of the dehydrogenation reaction. The deactivation of the catalyst is due to the carbonaceous deposits generated from the chemical adsorption of some alkaline substances in the catalytic run.