High severity process for xylene production employing a transalkylation zone for xylene isomerization

Patent · Tue Feb 10 04:00:00 EST 1987

OSTI ID:6730680

Schmidt, R J

A process is described for the production of a desired xylene isomer which comprises the steps of: (a) passing a hereinafter characterized first process stream, which comprises at least two xylene isomers, into an adsorptive xylene separation zone, withdrawing a product stream comprising the desired xylene isomer form the xylene separation zone and also withdrawing a raffinate steam comprising an undesired xylene isomer from the xylene separation zone; (b) passing a first feed stream comprising toluene, a hereinafter characterized recycle stream and at least a portion of the undesired xylene isomer content of the raffinate stream into a catalytic transalkylation zone. The zone contains a nonmetal transalkylation catalyst and operates at high severity conditions including a hydrogen to hydrocarbon mole ratio above 2:1 and a temperature over 426 degrees Centigrade, and forms a transalkylation zone effluent stream which comprises benzene, toluene, xylenes and C/sub 9/ aromatics; (c) separating the transalkylation zone effluent stream by fractional distillation to yield a benzene-rich process stream which is withdrawn from the process as a product stream, a toluene-rich process stream, a xylene-rich process stream comprising two xylene isomers, and a second process stream comprising C/sub 9/ aromatics; (d) recycling at least a portion of the toluene-rich process stream into the transalkylation zone as the recycle stream; and (e) passing at least a portion of the xylene-rich process stream into the xylene separation zone as the first process stream.

• Assignee: UOP, Inc., Des Plaines, IL
• Patent Number(s): US 4642406
• OSTI ID: 6730680
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALKYLATED AROMATICS
ALKYLATION
AROMATICS
BENZENE
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTIONS
DISTILLATION
ELEMENTS
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN
ISOMERIZATION
ISOMERS
NONMETALS
ORGANIC COMPOUNDS
QUANTITY RATIO
RECYCLING
SEPARATION PROCESSES
SORPTION
TOLUENE
XYLENES