The influence of organic and inorganic plasticizing agents on the properties of alumina supports and CoMo/Al2O3 catalysts for hydrotreating 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 investigated. Alumina supports have been studied by CHNS-analysis, XRD, nitrogen adsorption-desorption, TPD-NH3, IR spectroscopy of adsorbed pyridine methods. The mechanical strength value of the samples was also determined. The results show that the change of the plasticizing agent leads to drastic changes in textural characteristics of the obtained supports. The use of aqueous ammonia solution as a plasticizing agent resulted in an increase in the volume of pores in the support and an increase in the content of larger pores with the size of 13 – 50 nm by 4 – 16 times in comparison with other samples. In the case of the alumina support plasticized with diethylene glycol, in contrast, there is a decrease in the pore volume in the sample by almost 2 times in comparison with the sample plasticized with ammonia. It is explained by a 9 – 35 % increase in the portion of pores of < 7 nm in size compared to other samples. No significant effect of plasticizing agent on the concentration of acid sites was found. The alumina sample prepared with the addition of nitric acid stood out among the investigated series. According to the TPD-NH3 and IRS of adsorbed pyridine data, there is a decrease in the concentration of Lewis acid sites in comparison with the other samples.