The impact of molybdenum metal contamination on catalytic cracking units

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The widespread adoption of the slurry-bed residue hydrogenation process, along with the use of catalytic combination processes, has led to contamination issues related to the Mo trace in slurry-bed catalysts throughout the overall processing chain. It was discovered by chance that Mo was present and concentrated in the catalytic cracking equilibrium agents; this Mo originated from the inclusion of elemental catalyst MoS2 present in the hydrogenated dewaxing oil. As this hydrogenated oil or the backwash oil entered the riser, sulfides and oxides underwent conversion there. The transition metal Mo possesses both dehydrogenation and hydrogenation activities. In the hydrogen-rich, high-temperature, acidic, and olefin-rich environment of the riser reactor, does it have a stronger effect on dehydrogenating the feedstock or on hydrogenating and saturating the olefins? According to the current production data, compared with similar units, this system produces a higher amount of isobutane, has a lower content of olefins in gasoline, and exhibits significant hydrogen transfer reactions. We kindly ask everyone to help analyze the new issues related to the characteristics of the cracking reactions resulting from this new combined process.