A PROCESS FOR THE ENHANCEMENT OF THE CYCLELIFE OF A ZINC CHROMIUM BASED CATALYST IN THE SYNTHESIS OF 2-METHYLPYRAZINE

摘要

The invention relates to a process for the enhancement of the cycle life of a zinc-chromium based catalyst in the synthesis of 2-methylpyrazine. Pd promoted zinc-chromium catalyst is reported to give maximum conversions of ethylenediamine and propyleneglycol in the cyclization of reaction offering 70-80% yield of 2-methylpyrazine. The reaction is normally operated at isothermal conditions in the reaction temperature of about 400°C. However, the catalyst exhibits unacceptable conversion or selectivity to 2-methylpyrazine revealing a cycle-life of about 150 hours and a total catalyst life of less than 500 hours. In the present invention it has been claimed that by increasing the reaction temperature step-wise, starting from a low temperature, and by monitoring the levels of total conversion and selectivity towards pyrazine, it is possible to extend the cycle life by about 500 hours. Further, the catalyst after the first cycle of operation can be regenerated and by adopting the same step-wise temperature increase method, another cycle-life of 500 hours of cycle life. Thus a total life of 1500 hours has been demonstrated. Continuation of the same procedure could increase the life of the catalyst further.