Process and system for the production of isoprene

A process comprising:

• reacting a mixed C4 metathesis feed stream comprising isobutylene and 1-butene in the presence of a first metathesis catalyst under conditions sufficient to produce an intermediate product stream comprising 2-methyl-2-pentene and at least one of ethylene and propylene,
• fractionating the intermediate product stream to form a 2-methyl-2-pentene stream and at least one of an ethylene stream and a propylene stream,
• subjecting the separated 2-methyl-2-pentene stream to pyrolysis to produce a reaction product stream comprising isoprene, and
• separating the isoprene to form an isoprene product stream using fractionation.

A process comprising:

• reacting a mixed C4 metathesis feed stream comprising isobutylene and 2-pentene in the presence of a first metathesis catalyst under conditions sufficient to produce an intermediate product stream comprising propylene, 2-methyl-2-pentene, ethylene, 2,3-dimethyl-2-butene and 2-butene,
• separating the intermediate product stream in a multi-stage fractionation process to form a 2-methyl-2-pentene stream, a distillate stream containing ethylene and propylene, and a 2,3-dimethyl-2-butene stream,
• subjecting the separated 2-methyl-2-pentene stream to pyrolysis to produce a reaction product stream comprising isoprene, and
• separating the isoprene into an isoprene product stream using fractionation.

A system comprising:

• a first metathesis reactor configured to react isobutylene with at least one of 1-butene and 2-pentene to produce 2-methyl-2-pentene,
• a second reactor comprising at least one of an isomerization reactor configured to isomerize 2-butene to form 1-butene, and a metathesis reactor configured to react 2-butene with at least one of ethylene and 1-butene to produce propylene,
• a first multistage fractionation system configured to produce a 2-methyl-2-pentene stream and a 2,3-dimethyl-2-butene stream,
• a pyrolysis heater configured to crack the 2-methyl-2-pentene to produce isoprene and other hydrocarbons, and
• a second multistage fractionation system configured to separate isoprene from the other hydrocarbons.