Controlled hydrocracking process

Claim 1

IN A PROCESS FOR THE REACTION OF A HYDROCARBON FRACTION HAVING AN INITIAL BOILING POINT OF AT LEAST 400*F., A 50 PERCENT POINT OF AT LEAST 500*F. AND AN END BOILING POINT OF AT LEAST 600*F. WITH HYDROGEN IN THE PRESENCE OF A CATALYST WHICH COMPRISES BETWEEN ABOUT 0.05 AND 20 PERCENT BY WEIGHT OF AT LEAST ONE METAL OF THE PLATINUM AND PALLADIUM SERIES DEPOSITED UPON A COMPOSITE OF SOLID OXIDES OF AT LEAST TWO ELEMENTS OF GROUPS IIA, IIIB AND IV OF THE PERIODIC ARRANGEMENT OF ELEMENTS, SAID COMPOSITE HAVING AN ACTIVITY INDEX GREATER THAN 25, WHEREIN THERE IS AT ALL TIMES A NET CONSUMPTION OF HYDROGEN BY SAID FRACTION AND AT LEAST PERIODICALLY THE HYDROCARBON FRACTION IS CONVERTED AT A REACTION TEMPERATURE WITHIN THE RANGE ABOUT 600*F. TO ABOUT 900*F., TO LOWER BOILING PRODUCTS, THE IMPROVED METHOD OF OPERATION WHICH COMPRISES: ADDING NITROGENOUS COMPOUNDS TO SAID FRACTION TO INCREASE ITS NITROGEN CONTENT AND PERIODICALLY ADJUSTING THE QUANTITY OF NITROGENOUS COMPOUNDS ADDED TO EFFECT AT LEAST A PART OF THE CONTROL OVER THE EXTENT TO WHICH SAID HYDROCARBON FRACTION IS CONVERTED TO LOWER BOILING PRODUCTS, THE NITROGEN CONTENT OF THE FRACTION VARYING FROM TIME TO TIME BUT AT ALL TIMES BEING WITHIN THE RANGE ABOUT 0.01 TO 1 PERCENT BY WEIGHT OF THE FRACTION, AND AT ANY GIVEN TIME AN INCREASE IN ADDED NITROGENOUS COMPOUNDS BEING USED TO DECREASE THE EXTENT OF CONVERSION OF THE FRACTION TO LOWER BOILING PRODUCTS AND A DECREASE IN ADDED NITROGENOUS COMPOUNDS BEING USED TO INCREASE THE EXTENT OF CONVERSION OF THE FRACTION TO LOWER BOILING PRODUCTS, WHEREBY THE HYDROGEN CONSUMED DURING CONVERSION TO LOWER BOILING PRODUCTS IS LOWER THAN WHEN THE SAME CONTROL OVER THE EXTENT OF CONVERSION IS EFFECTED BY VARIATION OF REACTION TEMPERATURE ALONE.