Systems and processes integrating fluidized catalytic cracking with metathesis for producing olefins

A process for producing olefins, the process comprising:

• introducing a hydrocarbon feed to a high-severity fluidized catalytic cracking system;
• contacting the hydrocarbon feed with a cracking catalyst under high-severity conditions in the high-severity fluidized catalytic cracking system to produce a cracking reaction effluent comprising butenes, wherein the butenes comprise normal butenes and isobutene, where the high-severity conditions comprise a temperature of greater than or equal to 500° C., a residence time of less than or equal to 3 seconds, and a weight ratio of the cracking catalyst to hydrocarbon of 5:1;
• contacting a portion of the cracking reaction effluent with methanol in an MTBE reactor of an isobutene removal unit under reaction conditions sufficient to convert at least a portion of the isobutene in the portion of the cracking reaction effluent to methyl tert-butyl ether to produce an MTBE reactor effluent;
• separating the MTBE reactor effluent into at least an MTBE-containing effluent and a metathesis feed;
• passing the metathesis feed to a metathesis system, the at least a portion of the cracking reaction effluent comprising a cracking C4 effluent that includes at least butene;
• contacting the metathesis feed with a metathesis catalyst in the metathesis system, where the contacting causes at least a portion of the butenes in the metathesis feed to undergo a metathesis reaction to produce a metathesis reaction effluent comprising at least one of ethylene, propene, or both;
• and
• passing at least a portion of the MTBE-containing effluent back to the high-severity fluidized catalytic cracking system.

A process for producing olefins, the process comprising:

• contacting a hydrocarbon feed with a cracking catalyst under high-severity conditions to produce a cracking reaction effluent comprising at least butenes, where the high-severity conditions comprise a temperature of greater than or equal to 500° C., a residence time of less than 3 seconds, and a cracking catalyst to hydrocarbon weight ratio of greater than 5:1;
• contacting at least a portion of the cracking reaction effluent with a metathesis catalyst, where the contacting causes metathesis of at least a portion of the butenes in the portion of the cracking reaction effluent to produce a metathesis reaction product;
• separating the metathesis reaction product into a metathesis C5+ effluent and at least one olefin-containing effluent, the olefin-containing effluent comprising at least one of ethylene, propene, butenes, or combinations thereof;
• contacting the metathesis C5+ effluent with the cracking catalyst and the hydrocarbon feed under high-severity conditions to produce the cracking reaction effluent,
• in which the cracking reaction effluent further comprises isobutene and the process further comprises removing isobutene from at least a portion of the cracking reaction effluent to produce a metathesis feed,
• in which removing isobutene comprises:
• contacting the at least a portion of the cracking reaction effluent with methanol under reaction conditions sufficient to convert at least a portion of the isobutene in the portion of the cracking reaction effluent to methyl tert-butyl ether to produce an MTBE reactor effluent comprising the methyl tert-butyl ether;
• and
• separating the MTBE reactor effluent into at least an MTBE-containing effluent comprising the methyl tert-butyl ether and a metathesis feed comprising butene, where the metathesis feed is the at least a portion of the cracking reaction effluent contacted with the metathesis catalyst, and
• in which, the process further comprises contacting the MTBE-containing effluent with the cracking catalyst under high-severity conditions, where the contacting causes at least a portion of the methyl tert-butyl ether in the MTBE-containing effluent to undergo catalytic cracking reactions to produce at least a portion of the cracking reaction effluent.