Process for making acrylic acid

Claim 1

A PROCESS FOR THE MANUFACTURE OF ACRYLIC ACID WHICH COMPRISES REACTING A GAS MIXTURE CONSISTING ESSENTIALLY OF UP TO ABOUT 8% BY VOLUME EACH OF PROPYLENE AND OXYGEN, AND THE BALANCE BEING CARBON MONOXIDE, CARBON DIOXIDE, ACROLEIN, HYDROGEN AND STEAM AT TEMPERATURE WITHIN THE RANGE OF ABOUT 280*C. AND 450*C. AND UNDER A PRESSURE OF BETWEEN ABOUT 0.1 ATMOSPHERE ANSOLUTE AND 10 ATMOSPHERES GAUGE IN THE PRESENCE OF A CATALYST CONSISTING OF A MIXTURE OF OXIDES OF ELEMENTS OF THE GENERAL COMPOSITION FEABIBPCMOD, WHEREIN A AND B EACH REPRESENT A VALUE BETWEEN ABOUT 0.1 AND 12, C REPRESENTS A VALUE BETWEEN ABOUT 0.08 TO 10 AND D REPRESENTS A VALUE OF ABOUT 12, THE RESIDENCE TIME OF THE GAS-MIXTURE ON THE CATALYST BEING WITHIN THE RANGE OF BETWEEN ABOUT 0.1 AND 20 SECONDS, SEPARATING THE INITIALLY AQUEOUS ACRYLIC ACID CONTINUOUSLY FROM THE REACTION MIXTURE BY COOLING SAID MIXTURE TO A TEMPERATURE OF ABOUT +10*C, WHEREBY A MIXTURE OF WATER INCLUDED IN THE REACTED GAS TOGETHER WITH ACRYLIC ACID, ACETIC ACID AND A PORTION OF ACROLEIN FORMED CONDENSE, EXPELLING THE DISSOLVED PORTION OF ACROLEIN BY INJECTING STEAM INTO SAID MIXTURE, SEPARATING ACRYLIC ACID FROM SAID ACETIC ACID AND WATER, AND RETURNING THE EXPELLED ACROLEIN TOGETHER WITH THE CYCLE GAS CONSISTING ESSENTIALLY OF CARBON MONOXIDE, CARBON DIOXIDE, HYDROGEN, PROPYLENE AND ACROLEIN, AND WITH THE STARTING COMPONENTS PROPYLENE, OXYGEN AND STEAM, ABOUT 1.5 TO 3 MOLS OXYGEN AND ABOUT 3 TO 10 MOLS WATER IN THE FORM OF STREAM BEING ADDED PER MOL ADDED PROPYLENE, TO THE REACTION ZONE.