The Influence of Organic and Inorganic Plasticizing Agents on the Properties of Alumina Supports and CoMo/Al2O3 Hydrotreating Catalysts of Diesel Fractions. Part 1. Alumina Supports

The influence of organic (acetic acid, citric acid, and diethylene glycol) and inorganic (nitric acid and ammonia) plasticizing agents on the properties of alumina supports has been studied. Alumina supports were investigated using methods of elemental CHNS analysis, X-ray diffraction (XRD), low-temperature nitrogen adsorption–desorption, temperature-programmed desorption of NH3 (TPD-NH3), and FT-IR spectroscopy of adsorbed pyridine. The mechanical strength of the samples has been determined. The variation of the plasticizing agent had a significant impact on the textural characteristics of the obtained supports. The use of an aqueous ammonia solution as a plasticizing agent led to an increase in the pore volume in the support and an increase in the pore portion of 13–50 nm by 4–16 times compared to other samples. In the case of the alumina support plasticized with diethylene glycol there is a decrease in pore volume in the sample by almost 2 times compared to the sample plasticized with ammonia, which is explained by an increase in the proportion of pores smaller than 7 nm by 9–35%. No significant influence of the plasticizing agent on the concentration of acid sites of alumina was observed. Among the studied series, a sample of alumina prepared with the addition of nitric acid stood out. The results of TPD-NH3 and IR spectroscopy of adsorbed pyridine show a decrease in the concentration of Lewis acid sites (LAS) for this sample compared to the other samples.