Cyclic Deactivation with Steam of Metallated Cracking Catalysts: Catalytic Testing at the Bench Scale and the Pilot Scale

Abstract

Besides offering an adequate product distributions, a cracking catalyst must exhibit a reasonable resistance to the combined effect of high temperature, steam and metals. Two commercial catalysts, poisoned with Ni ? V (*2,500 ppm), are subjected to a large scale cyclic deactivation with steam, then characterized using mostly basic techniques and finally tested via bench scale and pilot scale cracking experiments. As examples of industrial deactivation, corresponding equilibrium catalysts (E-CATs) are investigated in parallel. Depending on their specific formulation, catalysts deactivate differently due to the exposition to high temperature steam and metals. The intrinsic deviations in the catalytic properties of cyclic deactivated catalysts (CD-CATs) related to E-CATs are further biases by the particular history of the latter and the particular reactor configuration and hydrodynamics, such deviations being magnified in the bench scale testing. Relative differences in activity and product yields (except for coke and hydrogen) of CD-CATs referred to E-CATs are below 10% at the pilot scale, and within 23% at the bench scale. Relative biases in hydrogen and coke yield of may be as high as 75 and 26% in the pilot plant and as much as 150 and 32% at the bench scale.

Zeolites in Fluid Catalytic Cracking (FCC)

“…The presence of steam at elevated temperatures in the FCC regenerator can cause dealumination and the eventual collapse of the zeolite structure [ 39 ]. Contaminant metals in the feed can cause further reduction in catalyst activity [ 33 ] and undesirable formation of hydrogen and coke during the cracking process [ 40 ]. The detrimental effects of the FCC feedstock metals (especially Ni, Na, Fe, and V) have been widely recognized in literature [ 33 , 40 -42 ].…”

Structure and acidity of individual Fluid Catalytic Cracking catalyst particles studied by synchrotron-based infrared micro-spectroscopy

“…To maintain a stable conversion level, an amount of fresh catalyst is added to the FCC unit after each cracking-stripping-regeneration round. This addition leads to a mixture of catalyst particles with a broad age distribution in the FCC unit and as a consequence also large heterogeneities in properties are observed when comparing individual catalyst particles and their performance [36,49]. The mixture that is present in a real FCC unit is for that reason called an equilibrium catalyst (Ecat) and it is expected that the age distribution within such an Ecat is also reflected in its acidity properties.…”