Cracking hydrocarbons with modified kaolin catalyst

Claim 1

PROCESS FOR CRACKING PETROLEUM OIL WHICH COMPRISES SUBJECTING THE OIL UNDER CATALYTIC CRACKING CONDITIONS TO CONTACT WITH A CATALYST COMPRISING A MODIFIED CLAY COMPOSITE OF LOW IRON CONTENT PREPARED BY TREATING A KAOLIN CLAY CONTAINING IRON AND ALUMINUM COMPOUNDS WITH ACID, THEREBY OBTAINING AN EXTRACT CONTAINING IRON IN SOLUTION, DISCARDING THE IRON-CONTAINING EXTRACT THUS OBTAINED, FURTHER TREATING THE KAOLIN WITH ACID TO AN EXTENT SUFFICIENT TO DISSOLVE A PORTION THEREOF CONSTITUTING A SUBSTANTIAL QUANTITY OF THE ALUMINIUM CONTENT OF THE KAOLIN, THEREBY FORMING AN ACID EXTRACT CONTAINING DISSOLVED ALUMINIUM SALT AND A KAOLIN RESIDUE COMPRISING SILICA AND ALUMINA, AND REACTING THE ALUMINIUM SALT-CONTAINING ACID EXTRACT WITH AN ALKALI METAL SILICATE IN THE PRESENCE OF SAID KAOLIN RESIDUE TO PRECIPITATE AN INSOLUBLE ALUMINIUM COMPOUND IN SAID KAOLIN RESIDUE.