US3904484A — Ethylbenzene-styrene separation

Claim 1

Independent Claim 143 words

IN A PROCESS INVOLVING DEHYDROGENATION OF ETHYLBENZENE IN ADMIXTURE WITH SUPERHEATED STEAM IN A DEHYDROGENATION REACTOR TO PRODUCE STYRENE MONOMER AND BY-PRODUCT STYRENE TAR RESIDUE, AND FRACTIONALLY DISTILLLING THE DEHYDROGENATION REACTION EFFLUENT UNDER SUBATMOSPHERIC PRESSURE IN A MULTISTAGE DISTILLATION UNIT COMPRISING A PLURALITY OF DISTILLATION STAGES TO SEPARATELY RECOVER STYRENE MONOMER, LOWER BOILING AROMATICS, PRIMARILY UNREACTED ETHYLBENZENE AND BY-PRODUCT STYRENE TAR RESIDUE COMPRISING STYRENE POLYMERS, C9+ ARMOMATIC HYDROCARBONS AND POLYMERIZATION INHIBITORS, THE IMPROVEMENT COMPRISING RECYCLING PREVIOUSLY RECOVERED STYRENE TAR RESIDUE TO SAID DEHYDROGENATION REACTION EFFLUENT AT A POINT UPSTREAM OF THE SEPARATION OF SAID STYRENE MONOMER AND ETHYLBENZENE SO AS TO MAINTAIN A LIQUID VOLUME RATIO IN THE RANGE FROM ABOUT 1 TO 20 VOLUMES OF STYRENE TAR RESIDUE TO 20 TO 1 VOLUMES OF THE REACTION EFFLUENT, AND DISTILLING THE DEHYDROGENATION REACTION EFFLUENT IN THE PRESENCE OF SAID RECYCLED STYRENE TAR RESIDUE.

Claim 2

Dependent Claim 143 words

IN A PROCESS INVOLVING DEHYDROGENATION OF ETHYLBENZENE IN ADMIXTURE WITH SUPERHEATED STEAM IN A DEHYDROGENATION REACTOR TO PRODUCE STYRENE MONOMER AND BY-PRODUCT STYRENE TAR RESIDUE, AND FRACTIONALLY DISTILLLING THE DEHYDROGENATION REACTION EFFLUENT UNDER SUBATMOSPHERIC PRESSURE IN A MULTISTAGE DISTILLATION UNIT COMPRISING A PLURALITY OF DISTILLATION STAGES TO SEPARATELY RECOVER STYRENE MONOMER, LOWER BOILING AROMATICS, PRIMARILY UNREACTED ETHYLBENZENE AND BY-PRODUCT STYRENE TAR RESIDUE COMPRISING STYRENE POLYMERS, C9+ ARMOMATIC HYDROCARBONS AND POLYMERIZATION INHIBITORS, THE IMPROVEMENT COMPRISING RECYCLING PREVIOUSLY RECOVERED STYRENE TAR RESIDUE TO SAID DEHYDROGENATION REACTION EFFLUENT AT A POINT UPSTREAM OF THE SEPARATION OF SAID STYRENE MONOMER AND ETHYLBENZENE SO AS TO MAINTAIN A LIQUID VOLUME RATIO IN THE RANGE FROM ABOUT 1 TO 20 VOLUMES OF STYRENE TAR RESIDUE TO 20 TO 1 VOLUMES OF THE REACTION EFFLUENT, AND DISTILLING THE DEHYDROGENATION REACTION EFFLUENT IN THE PRESENCE OF SAID RECYCLED STYRENE TAR RESIDUE.

Claim 3

Dependent Claim 106 words

A process of increasing the relative volatility between ethylbenzene and styrene monomer in admixture so as to facilitate separation of the admixture by distillation, comprising recovering styrene tar residue in the course of said distillation and, at a point upstream of the separation of said styrene monomer and ethylbenzene, adding previously recovered styrene tar residue comprising primarily styrene polymers to the admixture so as to maintain a liquid volume ratio in the range of from about 1 to 20 volumes of styrene tar residue to 20 to 1 volumes of the ethylbenzene-styrene monomer admixture and distilling said admixture in the presence of said styrene tar residue.

Claim 4

Dependent Claim 106 words

A process of increasing the relative volatility between ethylbenzene and styrene monomer in admixture so as to facilitate separation of the admixture by distillation, comprising recovering styrene tar residue in the course of said distillation and, at a point upstream of the separation of said styrene monomer and ethylbenzene, adding previously recovered styrene tar residue comprising primarily styrene polymers to the admixture so as to maintain a liquid volume ratio in the range of from about 1 to 20 volumes of styrene tar residue to 20 to 1 volumes of the ethylbenzene-styrene monomer admixture and distilling said admixture in the presence of said styrene tar residue.

Claim 5

Dependent Claim 97 words

A process according to claim 1 wherein the fractional distillation comprises the steps of fractionally distilling said dehydrogenation reaction effluent in a first distillation column to recover a fraction essentially comprising ethylbenzene, styrene monomer and styrene tar residue, fractionally distilling said fraction in a second distillation column to recover a fraction comprising styrene monomer and styrene tar residue, and fractionally distilling said latter fraction in a third distillation column to separately recover styrene monomer product and styrene tar residue, and further wherein at least a portion of said styrene tar residue is recycled to said second column.

Claim 6

Dependent Claim 24 words

A process according to claim 3 further including the step of cooling said styrene tar residue prior to introducing it to said second column.

Claim 7

Dependent Claim 31 words

A process according to claim 1 wherein the fractional distillation separation of ethylbenzene from styrene is conducted at a pressure in the range of about 150 to about 500 mm Hg.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-09-08	1979-03-10	1979-09-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-09-08	1983-03-10	1983-09-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-09-08	1987-03-10	1987-09-09	$7700.00	Window Closed / Lapsed

Ethylbenzene-styrene separation

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