Evolution from structured silicoalumina to Y molecular sieves
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Today, the active components of cracking catalysts have evolved from amorphous silica-alumina to Y-type molecular sieves, resulting in an improved distribution of mesopores in the matrix. What are amorphous silicoalumina and Y molecular sieves? The RFCC catalyst series developed in our country, such as REY, USY, REUSY, and REHY, all possess excellent properties including good heavy oil cracking performance, resistance to metal contamination, high coke selectivity, and good hydrothermal stability. What do these English words actually mean? I come across them often, but I’ve forgotten everything I learned in school; uh, now I regret it! ! !
What the original poster mentioned are all different names for modified Y-type molecular sieves; these names arise from the various modification methods used. REY, USY, REUSY, and REHY correspond respectively to Y molecular sieves modified with rare earth elements, super-stable Y molecular sieves (those that have undergone hydrothermal treatment), rare earth-enhanced super-stable Y molecular sieves, and rare earth-modified hydrogen Y molecular sieves – all of which are types of modified molecular sieves. For FCC catalysts, modified Y molecular sieves are currently used as the main cracking component; such catalysts can be prepared through in-situ growth or kneading methods, and they are combined with various FCC processes to convert heavy oils into lighter fractions.
RE = rare earth US = ultrastable