RELATING FEEDSTOCK COMPOSITION TO PRODUCT SLATE AND COMPOSITION IN CATALYTIC CRACKING .1. BENCH-SCALE EXPERIMENTS WITH LIQUID-CHROMATOGRAPHIC FRACTIONS FROM WILMINGTON, CA, GREATER-THAN-650 DEGREES-F RESID

The catalytic cracking behavior of compound types in the >650-degrees- F resid from a Wilmington, CA, 14.2-degrees API crude was investigated . Liquid chromatography (LC) was used to separate the resid into eight fractions. These fractions were used as feedstocks for a bench scale fluidized catalytic cracking (FCC) unit. Gasoline was produced almost exclusively from neutral (65% of whole resid) components. Acidic and b asic types were partially converted to coke plus small amounts of C1 a nd C2 gases, with the balance primarily carrying over as heavy liquid products. Gasoline composition depended on the type and quantity of ac id/base compounds present in the feed because both acidic and basic co mpounds inhibited catalytic reactions (beta-scission, hydrogen transfe r, etc.) to varying degrees. In accordance with prior work, basic nitr ogen compounds exhibited the largest inhibitory effect on cracking. Th eir effect is dependent on concentrations up to a limiting value which may correspond to saturation of susceptible catalyst sites. On an equ al weight basis, the effect of high boiling (high molecular weight) ba ses was less than those occurring in the 650-1000-degrees-F distillate range. Partitioning of nitrogen present in acidic (e.g., carbazole) f orms in the feed into liquid products was greater than for basic nitro gen. Thiophenic forms of sulfur partitioned more into liquid and less into gaseous (H2S) products than sulfide-type sulfur. Coke yield was a pproximately proportional to microcarbon residue test results for all feeds. Ongoing work with additional feedstocks has indicated behavior similar to that of Wilmington. Selected Wilmington liquid products are undergoing detailed analysis in order to determine relationships betw een feed versus product composition, particularly with respect to acid ic and basic types.