Title : Oxidative dehydrogenation of 4-vinylcyclohexene in the presence of modified forms of Zr, Fe-pentasyls
In this paper, the results of studying the catalytic conversion of 4-VCH in the presence of a pentasil-type zeolite modified with zirconium, iron, and gadolinium (or neodymium) oxides, as well as the effect of adding reaction by-products on the selectivity of the process are discussed.
The initial hydrocarbon – 4-VCH was obtained by dimerization of 1,3-butadiene and clear rectification (distillation) of the dimer fraction. Ethylbenzene, styrene, ethylcyclohexane, vinylcyclohexane, and ethylcyclohexene isomers, the purity of which was determined by the GLC method, were also used. The physicochemical constants of the above hydrocarbons corresponded to the literary data.
Zeolite Na-TsVM (Na-TsVM) at a temperature of 300-500?? practically does not show activity in the dehydrogenation of 4-VCH. The products of disproportionation and dehydrogenation of 4-VCH on this contact are observed only at a higher temperature (400-450??). The use of oxygen as an oxidizing agent (4-VCH:O2=1:0.2) has practically no effect on the isomerizing and dehydrogenating activity of HNa-TsVM. The introduction of iron and Zr and Gd cations into the composition of HNa-TsVM leads to a sharp increase in the activity of the catalyst in the direction of dehydrogenation. The results of our studies have shown that ternary systems –Fe,Zr,Gd/HNa-TsVM, with different contents of active components, demonstrate especially high activity in the oxidative regime (tab.). The latter are characterized by the most optimal combination of redox and acid-base properties.