Process Optimization Of Cyclohexanone Synthesis By Benzene Through Cyclohexene

Cyclohexanone is the key intermediate for caprolactam and adipic acid,the presursors to nylons.The process of cyclohexanone systhesis by benzene selective hydrogenation to cyclohexene-cyclohexene hydration is superior to the conventional cyclohexane oxidation process in pollution,energy consumption and resource utilization aspects.But there still has drawbacks,such as low-value by-product cyclohexane in the selective hydrogenation of benzene,which reduces the utilization of material,and the process refining system of cyclohexanol dehydrogenation usually means lager energy consumption when separating the close-boiling cyclohexanone-cyclohexanol mixture.As a solution,the non-oxidation partially and completely dehydrogenation of cyclohexane are proposed and combined with the hydrogenation and distillation process,the reaction heat is recovered through utilization in other rectification units,and heat-integrated distillation are involved to reduce the energy consumption of cyclohexanone distillation process to optimize the benzene-cyclohexene-cyclpohexanone process.In the research of partial dehydrogenation,the catalytic performance of Ru nano on three different supports（Al₂O₃、Mg Al O、Ni-Cu/Si O₂）was individually studied and compared.Then,the Ni-Cu content and Ru load on Ni-Cu/Si O₂ support was investigated respectively.The experiment results indicate that the properties of support can significantly influence the catalytic performance of Ru,0.4%Ru loaded on the Ni_0.85-Cu_0.15/Si O₂ catalyst touches the maximum 87%and 4.25%cyclohexene selectivity and yield at 300℃and 500℃,resepectively.The partially dehydrogenation product is directly separated by the existing benzene-cyclohexane-cyclohexene separation system to realize high value-added utilization of cyclohexane.In the research of completed dehydrogenation,the different Ru/Zn ratio of Ru-Zn/AC catalyst,Pt-Zn and Ru-Zn loaded on Al₂O₃ catalyst,the different Pt/Sn ratio of Pt-Sn/Al₂O₃ catalyst was individually studied.Besides,the effect was also investigated of Mn modified Ni-Cu/Si O₂ catalyst and the different Ni/Mn ratio of Ni-Mn/Si O₂on the dehydrogenation activity and benzene selectivity.The results show that the dehydrogenation activity of Pt is higher than Ru and non-precious Ni,Pt-Zn/Al₂O₃catalyst realizes complete conversion of cyclohexane at 300℃and the benzene selectivity is beyond 99%.Therefore,the complete dehydrogenation product can directly used as raw material for the selectivity hydrogenation of benzene to achieve100%utilization of carbon atoms.In the cyclohexanone distillation process,using the on-site four column cyclohexanone distillation as prototype scheme（two light ends column in distillation with recycle process,cyclohexanone column,cyclohexanol column）.Two configurations of distillation with recycle process（LSDRP,HSDRP）are compared for energy optimization upon the light ends columns,the optimized LSDRP turns out to be superior in energy-saving.The LSDRP thus used for lights removal system of prototype,four heat-integrated schemes including double-effect distillation,heat pump assisted distillation,double-effect plus heat pump distillation and double heat pump distillation are sequentially designed and evaluated based on total annualized coat（TAC）.The results show TAC reductions from prototype of 32.2%,23.6%,29.2%and 10.8%for corresponding heat-integrated distillation scheme.The double-effect distillation scheme contributs to the lowest TAC due to the 48.4%operating cost and8%capital cost saving.The process optimization can effectively reduce the energy consumption and cost investiment of cyclohexanone distillation process.