Kinetic Study Of Cyclohexane Oxidation Reaction Using Heterogeneous Catalysts

Abstract

Selective oxidation of cyclohexane is continued to be a most difficult and most challenging reaction for researchers. Industrial processes suffer from very low conversions (about 4 to 6%) and poor selectivity for K-A oil (about 70-80%). This shows tremendous scope for improvement in conversion or selectivity for KA-oil production. To develop new catalytic process for direct oxidation of cyclohexane in presence of oxygen or air with higher conversion and good selectivity is the main objective of the current researcher. Literature survey suggests that the air oxidation of cyclohexane produces only limited conversion, about 10-19% with 80-95% selectivity with gold metal and different supports like ZSM-5, MCM- 41, SBA-15. Further efforts and understanding is required to reduce activation energy and replace the traditional process of cyclohexane oxidation to K-A oil. Even thermodynamically 100% conversion of cyclohexane is feasible; practically cyclohexane conversion is kept about only 4-6 % in industrial operation and about 10-19% conversion of cyclohexane at laboratory scale is achieved due to severe selectivity problem. In current work,silver loaded alumina, MCM-41,SBA-15 were synthesized using wet-impregnation as well as in-situ method of catalyst preparation. Among various synthesized catalyst Ag/Al2O3 have a good conversion as well as selectivity. In the current work, 3 w/w% silver dopped with alumina (Ag/Al2O3) was showed the highest conversion and selectivity for K-A oil mixture. Effects of various parameters such as effect of temperature, air pressure, and speed of agitator have been studied using design of experiment concept. Based on that developed model it might be help in reduce number of experiments. In this work included designed and fabricated new reactor which can be operated at lower pressure and can provide enormous amount of surface area for mass transfer. It is expected that it can improve the rate of reaction as well as improve the conversion and selectivity for the desired products. The main objective of this work was to develop kinetic rate model of Langmuir– Hinshelwood–Hougen–Watson (LWHW) mechanism, Eieley-Ridedel and Mars–van Krevelen for cyclohexane oxidation reaction.Different reaction mechanism was proposed and power law model was well suitable .The activation energy for cyclohexane oxidation was determined as 15.19 kJ/mol.