Catalyst Regeneration in Light Naphtha Aromatization(LNA) Process.

Abstract

There are several light naphtha aromatization processes which are being attempted for commercial development ; however, none have so far been successful. We have been engaging in the development of Light Naphtha Aromatization (LNA) Process which employs zinc aluminosilicate catalyst. In this paper catalyst regeneration in fixed bed LNA process has been studied. The long-cycle-time stability of the LNA catalyst is well suited for service in semi-regenerative operation using conventional fixed bed reactors. Attention, however, is required in regenerative operation to avoid catalyst degradation due to coke-burning because zeolite structure may collapse due to severe hydrothermal atmosphere at higher temperatures. The temperature profile, which is critical in maintaining catalyst structure and activity, in the catalyst bed at the time of regeneration was estimated theoretically. Furthermore, a semi-commercial plant was designed to maintain the above temperature profile. In doing so, an insulator of 25 cm thickness, which has conductivity of 0.06 kcal/(mh°C), was installed for the 1.79 m-diameter reactors so that the maximum temperature difference through the radial direction might be lower than 45°C. During the operation of a semi-commercial scale reactor, the result of test run coincided with the estimated temperature difference. Furthermore, it showed no catalyst deactivation by regeneration.