CHARACTERISTICS OF LABORATORY-COKED RESID HDS CATALYST

A sample of commercial residual oil hydrotreating catalyst with a bimodal pore structure was coked to progressively higher levels with styrene at 425°C. Measurements of porosity by mercury intrusion-extrusion porosimetry, nitrogen adsorption-desorption porosimetry, and coronene diffusivity reveal the importance of the pore network to the structure of the coked catalyst. The role played by 'shielded' large pores within the structure is demonstrated. It is proposed that coking first occurs at the junctions between large, shielded pores and narrow connecting pores. The results are discussed in terms of the theoretical predictions of Mann and co-workers. © 1990.