Selective Oxidation Of Alcohols To Aldehydes And Ketones Over Simple Ion-exchanged Molecular Sieves

The oxidation of alcohols into aldehydes and ketones is a fundamental and important transformation in organic synthesis because the products are important precursors for various chemicals. The traditional alcohol oxidation using catalyst preparation difficult and containing precious metals,unstable and can not be reuse well,in the use of antioxidants are excessive inorganic oxidants,the reaction process produces a large number of by-products, and serious pollution to the environment. So how to efficient oxidation alcohol into the corresponding aldehydes ketones is a great research significance topic.With respect to the consideration of environment and economy, simple, inexpensive, and reusable solid catalysts have been attracting much attention. In this work, a series of non-noble transition-metal ion-exchanged zeolite catalysts have been prepared and applied in the catalytic oxidation of cyclohexanol and other alcohols with tert-butyl hydroperoxide (TBHP) to aldehydes or ketones in the absence of any solvent and additive. Among various catalysts tested, Cr3+-exchanged13X has exhibited the best activity with the highest efficiency of TBHP utilization, and been proven to be a recyclable heterogeneous catalyst for the oxidation of cyclohexanol with TBHP. The effects of the Cr loading, the reaction temperature, the reaction time, and the cyclohexanol/TBHP molar ratio have been investigated systematically. Furthermore, a feasible oxidation route is proposed.Based on the above work, some transition metal exchanged zeolites, such as M-ZSM-5, M-Beta, M-13X, M-SAPO-5, and M-SAPO-34, have been employed to catalyze the oxidation of benzyl alcohol with air.The experimental results show that Co ion-exchange to SAPO-5catalyst has a very good activity to the oxidation of benzyl alcohol with air.Meanwhile, some factors inclusive of cobalt content, reaction time, reaction temperature, solvents are investigated in detail. Obtained that with3%Co loading, rection temperature363K,dimetbylformamide as solvent, rection time7h,the benzyl alcohol conversion can be achieved82.5%, however, the selectivity of benzaldehyde was only62.5%, so this subject still need further research and discussion.