Study on the deactivation-aging patterns of fluid cracking catalysts in industrial units

Continuous Age Distribution Method for Catalytic Cracking 2. Understanding Nonidealities

“…In an earlier paper, we took the hypothesis that refinery zeolite collapse kinetics were separable into tetrahedral framework aluminum (AlO 4 – , Al T ) and silicon (SiO 4 , Si T ) contributions. The separability hypothesis is common in the study of differential equations and made reasonable in the present case because, as noted above, E-cat dealumination is much faster than Si T collapse. ,, After subtracting Al T , the earlier-derived expression for the fractional retention of zeolite framework Si T (eq 6) explained the full range of refinery and pilot plant data available in the literature. − Refineries, however, sometimes employ mixtures of catalysts, which can include two different zeolites. Some of our earlier laboratory results (Figures 3, 5, and 7 in ref ) also appear to be consistent with a zeolite mixture hypothesis.…”

“…We find that 10–20% of the original Si T is quickly lost in the newest portion of the age distribution, but most or all of the second type of zeolite is predicted to be retained in the refinery. This latter result does not represent well density separation data from refineries. − However, if we adopt the presteamed kinetic parameters for cat. E as the second zeolite and optimize the remaining three parameters to best fit the nonpresteamed data for cat.…”

“…That profile had been derived for the first-order decay of the tetrahedral silica (Si T ) portion of the zeolite, the zeolite being the most active and therefore the most important ingredient in the catalyst. Although fundamental kinetic and reactor models had been used and first-order Si T decay was confirmed by Pine, as well as by fitting published equilibrium catalyst density separation data, − we nevertheless found substantial deviations from ideal first-order Si T decay . The deviations were evident both by the classical Arrhenius method and by implementing the new continuous age distribution method (CADM) experimentally .…”

X‐ray Fluorescence Tomography of Aged Fluid‐Catalytic‐Cracking Catalyst Particles Reveals Insight into Metal Deposition Processes

“…Thus, as previously suggested, Ni was used to classify the particles based upon their catalytic age. [ 39 ] It was determined that ECAT1 is catalytically „younger“ than ECAT2. With this age classification method, these two catalyst particles can then be used to gain insight into possible temporal changes of metal deposition.…”

“…The ECAT particles (labelled as ECAT1 and ECAT2) under study were selected randomly and age classified by their Ni metal content. [ 39 ]…”