Bulk fluid catalytic cracking

Recent literature shows a growing trend to include free alumina in the formulation of fluid catalytic cracking (FCC) products. Over the last dozen years, FCC catalysts containing free alumina have been cited in the open and patent literature for benefits including (1) enhanced catalyst reactivity and selectivity (1-3). (2) more robust operation in the presence of metals in the petroleum feedstock (4-7). (3) improved attrition resistance (8.9). (4) improved hydrothermal stability against steam deactivation during regeneration (2.8). (5) increased pore volume and decreased bulk density (8), and (6) reduction of SOx emissions (10). 

In catalytic cracking the gas oil feed reacts to much lighter compounds, which causes a high convective flux from the catalyst surface to the bulk of the fluid. Therefore Fick s diffusion law is not applicable (assumes equimolar counter-diffusion) in the mass transfer calculations and as a result rigorous Maxwell-Stefan equations must be used. Due to the... 

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