The rate of growth of hydrotreatment of catalytic cracking feedstocks appears to be increasing. In part, this may be due to the ability to analyze catalytic cracking feedstocks in more detail and hence determine more precisely the need for and value of hydrogenation.
The newer hydrotreating catalysts result in higher hydrogen consumption and, when consideration is given to the kinetics and thermodynamic equilibria of the system, it is possible to operate in a manner such that the hydrogen is used to convert selectively those components most deleterious to catalytic cracking and to produce those which yield the most desirable components from catalytic cracking. The Aromatics Formation Reaction, a phenomenon in catalytic cracking, accentuated by hydrotreatment of catalytic cracking feed, undoes some of the potential benefit of hydrotreatment of catalytic cracking feed. The new zeolitic cracking catalysts are, somewhat surprisingly, very responsive to hydrotreatment of catalytic cracker feed.
Both conversion and gasoline yield show greater improvement with depth of hydrogenation using zeolitic catalysts than when using conventional amorphous catalytic cracking catalysts.
L'application de l'hydrotraitement aux charges de craquage catalytique est discutée en fonction des divers aspects de la chimie de chacun des deux procédés.
L'opération d'hydrotraitement peut être conduite de manière à détruire les composés les plus nuisibles pour le craquage catalytique et à obtenir les produits les plus désirables. Les considérations d'équilibre et de ciné- tique sont ensuite commentées pour le traitement par hydrogénation et pour le craquage catalytique.
Considering that both catalytic cracking and hydrotreating are well-established processes, it must be considered remarkable that the hydrotreating of catalytic cracker feed has not shown until recently much sign of being applied on a substantial scale. From the data' shown below, one observes that through 1964 catalytic cracker feed hydrotreating represented only about 1 % of the installed hydrotreating capacity in the United States but as of 1966 it has grown to about 5 %: in these statistics since some hydrotreatment of feed to catalytic cracking comes about in units designated differently (e.g., the first section of a hydrocracker*.
The reasons for the slow initial growth are not entirely clear since the process has been described in a laudatory fashion many times during the past ten years3, 4, 5, 6.
The more rapid rate of growth of catalytic cracker feed hydrotreating in the last few years may be attributable to the development of new and improved hydrotreating Year 1967 1963 1964 1965 1966 (Estimated) Cat. Cracker Feed Hydrotreating, bbl/D. .. ... 16,300 26,800 95,300 111,100 186,100 Total U.S. Hydrotreating Capacity. .. .. ... 2,536,690 2,748,930 2,929,465
