Studying the Characteristics of a Waste Industrial Co-\Mo/Al(2)O(3)Catalyst for the Deep Hydrotreatment of Diesel Fuel

The physicochemical properties of a waste industrial Co-\Mo/Al(2)O(3)catalyst for the deep hydrotreating of diesel fuel are studied. IR spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), and scanning electron microscopy (SEM) are used to establish that the catalyst surface is uniformly coated with a coke film. This soft coke is mostly a mixture of saturated hydrocarbons with a low degree of branching in their structure. The coke is oxidized at temperatures of 190-375 degrees C (soft coke) and 375-525 degrees C (hard coke); its quantitative removal is achieved by means of oxidative calcination in air for 3 h at 550 degrees C. X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption, and chemical analysis are used to show that the waste catalyst undergoes considerable structural transformation with a 7.7% drop in the Mo content and the accumulation of Fe, Ha, and V impurities. As a result of sintering, its specific surface area and total pore volume are reduced by 31.5 and 28.4%, respectively. The obtained data are needed to develop a scheme for its recycling.