Production of phthalic anhydride by catalytic oxidatkon of o-xylene

Claim 1

A PROCESS FOR THE VAPOR-PHASE CATALYTIC OXIDATION OF O-XYLENE TO PHTHALIC ANHYDRIDE WHICH COMPRISES BRINGING A GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND GASES CONTAINING MOLECULAR OXYGEN WHICH ARE INERT UNDER THE CONDITIONS OF THE REACTION, SAID GAS CONTAINING 150 TO 900 G. O-OXYLENE PER CUBIC METER S.T.P. OXYGEN AND FURTHER CONTAINING 10**-3% TO 2% BY WEIGHT WITH REFERENCE TO O-XYLENE OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF BROMINE AND BROMINE CONTAINING COMPOUNDS BEING GASEOUS AT THE REACTION TEMPERATURE INTO CONTACT WITH A CATALYST MAINTAINED IN A FLUIDIZED CONDITION IN THE APPROXIMATE TEMPERATURE RANGE OF 250 TO 380*C. FOR A RESIDENCE PERIOD OF FROM 5 TO 50 SECONDS, SAID CATALYST BEING A SOLUTION APPLIED TO A POROUS INERT CARRIER OF 5 TO 30% BY WEIGHT OF VANADIUM PENTOXIDE WITH REFERENCE TO THE SOLUTION IN A SALT OF PYROSUSLFURIC ACID SELECTED FROM THE GROUP CONSISTING OF POTASSIUM PYROSULFATE AND MIXTURES OF POTASSIUM PYROSUSLFATE AND SODIUM PYROSULFATE IN A RATIO BY WEIGHT OF UP TO 1:1.