초록 ▼

This process discloses a reduction in the content of ammonia in a regeneration zone off gas of a fluid catalytic cracking unit by the select recycle of certain sized ammonia decomposition catalyst particles. The ammonia decomposition may be aided by injection of NOx into the off gas. The particles a

This process discloses a reduction in the content of ammonia in a regeneration zone off gas of a fluid catalytic cracking unit by the select recycle of certain sized ammonia decomposition catalyst particles. The ammonia decomposition may be aided by injection of NOx into the off gas. The particles are acquired from a separation means through which is passed the regeneration zone off gas. A solid-free regeneration zone off gas and a stream of solid particles, including a noble metal dispersed on an inorganic support, having a size of from 10 to 40 microns, are acquired. The latter segregated particles are then injected into the regeneration zone at a predetermined make-up rate to insure a very short residence time in the dense phase of the regeneration zone and to provide a relatively constant concentration of the NH3 decomposition catalyst in the dilute phase of the regeneration zone to convert NH3 to N2 and water vapor. The regeneration zone is operated in a partial combustion mode defined by a CO content of from 1 to 6 percent by volume.

대표청구항 ▼

In a process for the fluidized catalytic cracking of a higher molecular weight hydrocarbon to a lower molecular weight hydrocarbon which process comprises: (a) contacting, in a cracking zone, said higher molecular weight hydrocarbon with a cracking catalyst, wherein said cracking catalyst becomes de

In a process for the fluidized catalytic cracking of a higher molecular weight hydrocarbon to a lower molecular weight hydrocarbon which process comprises: (a) contacting, in a cracking zone, said higher molecular weight hydrocarbon with a cracking catalyst, wherein said cracking catalyst becomes deactivated with coke deposits while being employed in said cracking; (b) withdrawing deactivated cracking catalyst particles from said cracking zone having said coke deposited thereon and passing said coked catalyst to a regeneration zone containing an ammonia decomposition catalyst and an inlet means for admission to said regeneration zone of a sufficient quantity of an oxygen-containing gas to operate said regeneration zone in a mode of partial combustion as defined by the presence of from 1 to 6 volume percent of CO in the regeneration zone: (c) contacting the coke-deposited cracking catalyst with said oxygen-containing gas in the presence of said ammonia decomposition catalyst comprising a noble metal dispersed on an alumina support to form a regeneration zone effluent stream comprising spent regeneration gas, regenerated catalyst, and ammonia decomposition catalyst; (d) withdrawing said regeneration zone effluent stream from said regeneration zone and passing said regeneration zone effluent stream to a separation means wherein said spent regeneration gas, regenerated catalyst and ammonia decomposition catalyst are separated and wherein said spent regeneration gas is passed to a CO combustion zone; (e) combusting said spent regeneration gas in said CO combustion zone in the presence of an oxygen-containing gas to form CO2, hydrogen and water vapor; and (f) passing said CO2, hydrogen and water vapor to ambient air as emissions from said process, with a reduced amount of NOx as a result of the improvement of said process which consists of separating said ammonia decomposition catalyst in step (d) from said regenerated catalyst and spent regeneration gas in said separation means to attain a stream containing said ammonia decomposition catalyst in a select size of from 10 to 40 microns and recycling said select sized ammonia decomposition catalyst either to (1) said regeneration zone or (2) said regeneration effluent stream intermediate to said regeneration zone and said CO combustion zone.