CHARACTERIZATION OF THE EFFECTS OF VANADIUM TRAPS IN CRACKING CATALYSTS BY IMAGING SECONDARY-ION MASS-SPECTROMETRY AND MICROACTIVITY TEST

The vanadium trapping effect of Mg and La containing additives in crac king catalyst contaminated with 2300 ppm Ni and 4700 ppm V has been an alyzed by microactivity test (MAT) and imaging secondary ion mass spec trometry (SIMS). The results of SIMS imaging are consistent with crack ing activity data and show that the La/spinel is a superior vanadium t rap for the fluid catalytic cracking of hydrocarbons (FCC) operation. La/spinel serves as a dual function additive for both vanadium trap an d SOx removal. The optimum amount of La/spinel added to the cracking c atalyst is about 15% by weight. This results in an increased catalytic activity, an increase in gasoline yield, and a decrease in coke and g as factors. The MgAl2O4 phase of Mg/Al2O3 additive is found capable of trapping vanadium while its MgO of Mg/Al2O3 phase can migrate to zeol ite particles (the active component of the FCC catalyst) that, in turn , causes a decline in the activity of that catalyst.