Bodul N. Oligomerization of tetrahydrofuran and Beckmann rearrangement of cyclohexanone oxime to e-caprolactam on solid acid catalysts

The dissertation is devoted to development of solid acid catalysts for liquid-phase oligomerization of tetrahydrofuran and Beckmann rearrangement of cyclohexanone oxime into caprolactam at moderate temperatures (T< 130 °С). It was found, that an activity of solid acids in the oligomerization reaction of tetrahydrofuran to polytetramethyleneglycol acetate (PTME) correlates with the strength of their acid sites in the such order: WO3/ZrO2-SiO2>WO3/ZrO2>ZrO2-SiO2>DOWEX DR-2030. Superacid WO3/ZrO2-SiO2 catalyst (Н0 > -13.2; 265 m2/g) of tetrahydrofuran oligomerization has been developed. The catalyst provides 0.3 g PTME/gcat/h space time yield in a flow reactor at 60 °C. It was found, that the degree of tetrahydrofuran oligomerization is inversely proportional to a content of acetic anhydride in a reaction mixture, that allows to control a molecular mass of obtained PTME in an interval of Mn = 400-1800. The scheme of THF oligomerization with participation of acetanhidrate, which explains obtained dependence, is presented. The high-acidic WO3/ZrO2-SiO2 and ZrO2-SiO2 oxides provide 100 % conversion of cyclohexanone oxime in polar solvents at 40-130 °С. However, these oxides quickly lost activity in the result of blocking active sites by protonated caprolactam molecules.