Regeneration of fluidised bed cracking catalysts - under conditions giving low coke content and high activity

摘要

Catalytic cracking of hydrocarbons in fluidised beds, with regeneration of the catalyst in a bed fluidised with an oxygen-contg. gas, in which the catalyst dwell time in the dense phase is 3-10 mins., to give a coke burn-off rate of 0.12-1.0 kg./kg. catalyst/h., at a temp. of 732-788 degrees C., using a stoichiometric excess of oxygen. A concn. of 1-5 vol. % oxygen and 0-500 ppm. CO is maintained in the waste gas, coke content in the regenerated catalyst reduced to 0.12 wt. % max. and substantially all the CO burnt to CO2 while in the dense phase. After-burning of CO to CO2 in the dilute phase, causing high temps. which damage the cyclones and deactivate the catalyst, is prevented. The catalyst is completely regenerated by removal of coke, and compsn. of the waste gas is held within strict anti-pollution levels.