ABSTRACT
Hydrotreating, the catalytic conversion and removal of organic sulfur, nitrogen, oxygen and metals from petroleum crudes at high hydrogen pressures and accompanied by hydrogenation of unsaturates and cracking of petroleum feedstocks to lower molecular hydrocarbons plays an ever increasing key role in the refinery. Hydrotreating of petroleum residua feedstocks involves three important reactions: hydrodesulfurization, hydrodenitrogenation, and hydrodemetallization for removal of organically-bound sulfur, nitrogen, and metals respectively. Catalyst size and shape also play important roles in the design of active, stable hydrotreating catalysts. Shaped extrudates, e.g. stars, trilobes and quadralobes, are commonly used in hydrotreating applications, since they provide the advantages of high geometrical surface area, low pressure drop, high crush strength and high contaminant metals tolerance. A key aspect of catalyst design in hydrotreating is the optimization of pore structure. Fe and Na salts enter hydrotreating reactors mainly as particulate matter which can plug catalyst pores and even beds.
