Pyrolysis of animal by-products provides pyro-oil that contains about 10wt% nitrogen mainly in aliphatic compounds and virtually no sulfur. The nitrogen should be removed from the oil preferably by hydrodenitrogenation (HDN) to obtain liquid fuel and ammonia. In order to understand the catalytic HDN processes of such bio-oils the HDN of propylamine (PA) was studied as model reaction over silica-supported Ni2P and Ni catalysts. Catalysts were prepared by H2-reduction of catalyst precursor NiO/phosphated silica gel and NiO/phosphated SBA-15 silica material and NiO/silica gel. The catalyst surface was characterized by Diffuse Reflectance Infrared Fourier Transform Spectroscopic (DRIFTS) examination of adsorbed CO. It was shown that the Ni2P particles had a highly defected structure in the initial reduced state of the catalyst but were rapidly converted to ordered crystals in contact with PA under reaction conditions. The HDN reaction of PA was studied using a flow-through tube reactor and also by in situ DRIFTS experiments in the 16-60bar pressure and 200-400°C temperature range. Below about 300°C the Ni2P catalysts were active in the direct hydrogenolysis of the CN bond of PA, however, the main reaction was the PA disproportionation to dipropylamine (DPA) and ammonia. Above about 300°C the hydrogenolysis of the DPA CN bond became the main reaction. Near to full HDN of PA could be attained without hydrogenolysis of CC bond. In contrast, Ni/silica gel catalyst was hardly active in the direct C-N hydrogenolysis of PA but was active in the PA disproportionation to DPA. Above about 300°C reaction temperature ammonia, less propane, and significant amount of methane and ethane were formed.
- Delplot analysis
ASJC Scopus subject areas
- Environmental Science(all)
- Process Chemistry and Technology