Maintaining catalyst activity in a hydroforming process

Claim 1

IN THE HYDROFORMING OF A NAPHTHENIC FEED STOCK IN A REACTOR WITH A FIXED BED OF PILLED CATALYST CONSISTING ESSENTIALLY OF GRAMMA ALUMINA, FROM ABOUT 5 TO 15 WEIGHT PERCENT, BASED ON THE GAMMA ALUMINA, OF MOLYBDENA, AND NOT MORE THAN ABOUT 5 WEIGHT PERCENT, BASED ON THE GAMMA ALUMINS, OF SILICA, SAID PILLS BEING OF SUBSTANTIALLY UNIFORM SIZE IN THE RANGE FROM ABOUT 1/8 TO 1/2 INCH IN DIAMETER, SAID CATALYST HAVING AN AVERAGE BULK DENSITY OF AT LEAST ABOUT 65 POUNDS PER CUBIC FOOT AND A SURFACE AREA OF AT LEAST ABOUT 90M.2/GM., THE IMPROVED METHOD OF OPERATION WHICH COMPRISES HYDROFORMING SAID FEED STOCK UNTIL THE AVERAGE BULK DENSITY OF SAID BED IS LESS THAN ABOUT 60 POUNDS PER CUBIC FOOT, DISCONTINUING SAID HYDROFORMING OPERATION, WITHDRAWING SAID BED OF PILLED CATALYST FROM SAID REACTOR, SEGREGATING SAID BED OF CATALYST INTO AN ACTIVE FRACTION OF CATALYST PARTICLES HAVING A BULK DENSITY OF AT LEAST ABOUT 60 POUNDS PER CUBIC FOOT AND A DISCARD FRACTION OF CATALYST PARTICLES OF LESSER BULK DENSITY, RETURNING SAID ACTIVE FRACTION TO SAID REACTOR TOGETHER WITH AN AMOUNT OF FRESH PARTICLES EQUIVALENT TO THE AMOUNT OF CATALYST DISCARDED AND THEN RESUMING SAID HYDROFORMING REATION.