Hydrotreatment

Hydrotreatment, also known as hydroprocessing, is a family of catalytic chemical reactions used in petroleum refining and related industries in which a hydrocarbon feed is treated with hydrogen to remove heteroatoms such as sulfur, nitrogen, and metals, and to saturate unsaturated hydrocarbons. The primary goals are to upgrade feeds, improve product quality, and reduce sulfur and nitrogen content to meet environmental and product specifications.

Industrial hydrotreating typically employs sulfided transition-metal catalysts, most commonly cobalt-molybdenum (Co-Mo) or nickel-molybdenum (Ni-Mo) on an aluminum oxide support, with possible additions of tungsten or noble metals. The catalysts operate under high hydrogen partial pressure and elevated temperature, and are maintained in a sulfided state. Catalyst activity is sustained through sulfurization pretreatment and regeneration cycles, while deactivation occurs from coke formation and metals deposition in the feed.

The process is carried out in fixed-bed or slurry reactors, often in series, at temperatures generally between 250 and 400°C and pressures from about 20 to 130 bar, with substantial hydrogen consumption and recycling. Hydrotreating can be configured to target specific contaminants or hydrocarbon structures, and is frequently integrated with other upgrading steps in a refinery.

Common variants include hydrodesulfurization (HDS) for sulfur removal, hydrodenitrogenation (HDN) for nitrogen removal, and hydrodemetallization (HDM) for metals removal. In addition to producing cleaner fuels such as naphtha, diesel, and jet fuel, hydrotreating saturates aromatics to improve stability and cold flow properties. Hydrotreatment is also applied to renewable feedstocks, such as vegetable oils and animal fats, to produce renewable diesel and other biofuels through hydroprocessing of oxygen-containing compounds.