4. CONCLUSIONS
We successfully demonstrated the feasibility of the novel cyclohexene esterification–hydrogenolysis process for the production of cyclohexanol, the intermediate for the production ofε -caprolactam. The bench-scale studies verified that cyclohexene esterification is thermodynamically and kinetically more favorable than cyclohexene hydration. And the Cu1Zn1Si2La0.1catalyst afforded high conversion and selectivity in the hydrogenation of cyclohexyl acetate to cyclohexanol. The cyclohexene esterification–hydrogenation process was operated smoothly in a long term on a pilot-scale demonstration unit. Moreover, this process not only shows high overall atom economy comparable to the cyclohexene hydration process, but also exhibits much higher catalytic efficiency than the phenol hydrogenation process. This work elegantly bridges the gap between the Asahi’s process of benzene partial hydrogenation to cyclohexene and Thomas and Raja’s process of one-step transformation of cyclohexanone to ε -caprolactam, thus completing the last technological puzzle for the development of a next-generation process for the manufacture of nylon-6 from benzene in a safe, efficient, and green manner.