The refining of residual oils, that contain many kinds of metals, leads to metal deposition on FCC catalysts, so the problem of the metal poisoning of FCC catalysts becomes more and more important. Metal poisoning results in the decrease in cracking activity and selectivity of the catalysts accompanied with the high coke and hydrogen yields at the expense of light liquid product (1-3). Two kinds of important metal contaminant are nickel and vanadium. It is well known that nickel quenches cracking activity and increases dehydrogenation activity through deposition on the catalysts, but it is not responsible for the destruction of the framework of the molecular sieve (4-5). In contrast, vanadium is the predominant material inducing the collapse of the crystalline structure of the molecular sieve. In the regenerator, catalysts loaded with vanadium react with high temperature steam to form vanadic acid, H_3VO_4, which then enters into the crystal of Y-type zeolite and interacts with it, so the zeolite is destroyed (6-8). A report on what the product of such interaction is has not been published to our knowledge. Metal poisoning induced by vanadium is irreversible, at the same metal levels, vanadium can do more harm to the FCC catalysts than nickel. This paper is concerned with the preparation of inorganic solid vanadium passivators and the study of the mechanism of vanadium poisoning and vanadium passivation. Good passivation shown by microactivity test MAT is obtained.
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