Catalytic hydrodenitrogenation of propionitrile over supported nickel phosphide catalysts as a model reaction for the transformation of pyrolysis oil obtained from animal by-products

The catalytic hydroconversion of propionitrile (PN) was studied over supported nickel and nickel phosphide catalysts. PN was used as a model compound of aliphatic nitriles in pyrolysis oil obtained from animal by-products. Silica gel and Laponite were used as supports. The structure and particle size of the supported active phase was characterized by X-ray diffractometry and transmission electron microscopy. Catalytic experiments were carried out using a flow-through tube reactor at temperatures between 200 and 400 °C, total pressure of 30 bar, and H2/PN molar ratio of 10. High-pressure operando diffuse reflectance infrared Fourier transform spectroscopy experiments were carried out to study the species on the catalyst surface during reaction. The results substantiated that propane-1-imine (PI) is a surface intermediate of propylamine, dipropylamine and tripropylamine formation. The conversion of PN to hydrocarbon and ammonia hardly proceeded below 300 °C but became dominating reaction between 350 and 400 °C. Brønsted acid sites were not required for the reactions. Supported Ni2P catalysts catalyzed hydrogenolysis of C–N bonds only, whereas also the C–C bonds suffered significant cleavage over supported Ni catalyst.