For a strongly endothermic catalytic dehydrocyclisation a new design o
f an annular slit reactor was evaluated. The major advantage of the de
sign is an optimised temperature profile. Consequently, both a higher
selectivity and a higher conversion were achieved. Furthermore, the fo
rmation of a problematic side product was significantly reduced, leadi
ng to a simplification of the subsequent purification step and an incr
eased productivity. From an economic point of view, yearly savings of
up to CHF 1 Mio. are anticipated compared to the present manufacturing
costs.