Prevention of coke formation in pyrolysis of acetone

Claim 1

IN A PROCESS FOR THE MANUFACTURE OF KETENE BY THE PYROLYSIS OF ACETONE WHEREIN A CHEMICAL REACTION IN A FERROUS METAL CONTAINER, THE INSIDE SURFACE OF WHICH IS COMPOSED OF 23-27% CHROMIUM, 12-20% NICKEL, AND THE BALANCE SUBSTANTIALLY IRON, RESULTS IN EXCESSIVE COKE FORMATION OF THE INNER SURFACE OF THE CONTAINER, THE METHOD OF CONDITIONING SAID SURFACES AND PREVENTING SAID EXCESSIVE COKE FORMATION WHICH COMPRISES PRELIMINARILY CONTACTING SAID SURFACE WITH ACETONE AT A TEMPERATURE BETWEEN 1150* AND 1400* F. UNTIL EXCESSIVE AMOUNTS OF COKE ARE FORMED ON THE SURFACE, SUBJECTING COKE-COVERED SURFACE OF A REGENERATION TREATMENT WITH STEAM AND AIR AT A TEMPERATURE BETWEEN 1600 AND 1700* F. UNTIL THE COKE IS REMOVED, REPEATING THE PYROLYZING AND REGENERATING STEPS SEVERAL TIMES UNDER THE SAME CONDITIONS AND THEN REPEATING THE SAME STEPS FOR SEVERAL MORE TIMES WHILE MAINTAINING A TEMPERATURE OF 1400-1500* F. IN THE REGENERATION STEP UNTIL COKE NO LONGER FORMS ON THE SURFACE.