Dehydrogenation of ethylbenzene to styrene

Claim 1

METHOD FOR PRODUCING STYRENE IN HIGH CONCENTRATION VIA THE CATALYTIC DEHYDROGENATION OF ETHYLBENZENE IN A MULTI-BED REACTION ZONE WHICH COMPRISES (A) ADMIXING ETHYBENZENE WITH WATER IN AN AMOUNT EQUIVALNET TO A FIRST MINOR PORTION OF HEREINAFTER SPECIFIED TOTAL STEAM; (B) HEATING SAID ADMIXTURE TO A TEMPERATURE FROM 900* F. TO 1100*F., BUT AT LEAST 150*F. LESS THAN THE HEREINAFTER SPECIFIED REACTION ZONE INLET TEMPERATURE BY INDIRECT HEAT EXCHANGE OF THE ADMIXTURE WITH THE REACTION ZONE EFFLUENT; (C) SEPARATELY HEATING A SECOND MINOR PORTION OF SAID TOTAL STEAM TO A TEMPERATURE FROM 900*F. TO 1100* F., BUT FROM 100* TO 50*F. LESS THAN SAID REACTION ZONE INLET TEMPERATURE; (D) BLENDING SAID SECOND PORTION OF STEAM WITH SAID HEATED ADMIXTURE TO FORM A TOTAL FEED STREAM; (E) HEATING THE FEED STREAM TO A TEMPERATURE FROM 1100*F. TO 1400*F. AS THE SPECIFIED REACTION ZONE INLET TEMPERATURE; (F) CONTACTING THE HEATED FEED STREAM WITH DEHYDROGENATION CATALYST CONTAINED IN A FIRST BED OF SAID REACTION ZONE UNDER CONDITIONS SUFFICIENT TO CONVERT AT LEAST 30% BY WEIGHT OF THE ETHYLBENZENE THEREIN TO STYRENE; (G) HEATING AT LEAST A THIRD MINOR PORTION OF SAID TOTAL STEAM TO A TEMPERATURE FROM 1200*F. TO 1500*F., SAID TEMPERATURE BEING AT LEAST 100*F. MORE THAN SAID REACTION ZONE INLET TEMPERATURE; (H) ADMIXING SAID HEATED THIRD PORTION OF STEAM WITH THE TOTAL EFFLUENT FROM THE FIRST CATALYST BED TO FORM A SECOND FEED MIXTURE IN AN AMOUNT SUCH THAT THE SECOND FEED MIXTURE IS AT A TEMPERATURE SUBSTANTIALLY THE SAME AS SAID REACTION ZONE INLET TEMPERATURE; (I) CONTACTING THE SECOND FEED MIXTURE WITH DEHYDROGENATION CATALYST IN A SECOND BED OF SAID REACTION ZONE UNDER CONDITIONS SUFFICIENT TO CONVERT AT LEAST 15% BY WEIGHT OF THE ETHYLBENZENE PRESENT THEREIN TO STYRENE; (J) WITHDRAWING THE TOTAL REACTION ZONE PRODUCT STREAM FROM THE ZONE INTO INDIRECT HEAT EXCHANGE WITH SAID ETHYLBENZENE ADMIXTURE AS HEREINABOVE SPECIFIED, SAID PRODUCT STREAM NOW CONTAINING FROM 2 TO 10 POUNDS OF STEAM PER POUND OF ETHYLBENZE IN SAID ADMIXTURE AS THE TOTAL STEAM SPECIFIED, BUT NOT EXCEEDING 5 POUNDS OF STEAM PER POUND OF STYRENE IN SAID PRODUCT STREAM; AND (K) RECOVERING STYRENE IN HIGH CONCENTRATION FROM THE HEAT EXCHANGED REACTION ZONE PRODUCT.