Metal contaminant effects on the properties of a silica-rich fluid cracking catalyst

Metal-Resistant Fluid Cracking Catalysts

“…Initially, Ni was found to be homogeneously distributed on the catalyst surface; then as Ni levels increased above 2%, surface enrichment of Ni occurred (56). Ni migration can be correlated with the luminescence quenching of the rare-earths (RE) containing Y-zeolite (REY) present in the FCC matrix (16). Steaming induced Ni migration from the luminescence centers (REY crystals) and partial restoration of band intensity was observed (16).…”

“…The ability of a matrix to minimize Ni dispersion and of the matrix components to form chemically inert Ni-compounds will control the activity of this metal for catalyzing those secondary cracking reactions during gas oil conversion that generates light gases and coke at the expense of gasoline make (10,18,27,28,31). Recently, it has been reported that the deleterious effects of Ni can be reduced by FCC whose matrix consists of a partially dealuminated kaolin mineral embedded in a SiO z -rich support (16,18).…”

“…to 70A in size have been observed by transmission electron microscopy (TEM), Figure 4. The Si0 2 -rich matrix prevents good Ni distribution on the surface; large Ni crystallites and inert NiSi0 3 formation are believed responsible for the catalyst's low carbon and hydrogen generation during gas oil cracking at MAT conditions (16,18). XRD, scanning transmission electron microscopy (STEM), and x-ray fluorescence have also been used to observe nickel crystallites formation on a catalyst surface (55).…”

Interactions between heavy metals and clay matrix in fluid catalytic cracking catalysts

“…The NiO phase was rather distinctive in the products of interaction of kaolin and acid-modified kaolin (AMK) with nickel oxide (2θ = 43.5 • , 37.2 • as shown in PDF 4-0835), pointing to the fact that they could not react with nickel. In the product of caustic-modified kaolin (CMK) and nickel reaction, NiO phase could not be examined, in- dicating that CMK reacted with nickel and formed a new crystal phase-NiAl 10 O 16 (2θ = 37.6 • and 37.0 • as shown in PDF 37-1292) that was more stable than NiAl 2 O 4 [4]. This was why CMK displayed excellent anti-nickel contamination performance in FCC catalyst.…”

“…Although the zeolite provides most of the cracking activity of the FCC catalyst, the matrix fulfills both physical and catalytic functions. As to the interactions of Ni and V species with FCC catalyst, a great amount of research work had been focused on the active component (zeolite Y), and little concern had been given to kaolin matrix that amounts to 20-60% in FCC catalyst [2][3][4]. The interaction of vanadium-kaolin was conventionally considered as a physical process in which vanadium species were buried partially in kaolin through adsorption and were therefore passivated.…”