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==History== | ==History== | ||
The history of the process goes back to the later 1920s when a plant for the commercial hydrogenation of brown coal was commissioned at Leuna in Germany. Tungsten sulphide was used as a catalyst in this one-stage unit , in which high reaction pressures, 200-300 bar, were applied. The catalyst displayed a very high hydrogenation activity: the aromatic feedstock, coal and heavy fractions of oil, containing sulphur, nitrogen and oxygen, was virtually completely converted into paraffins and isoparaffins. The result of the Leuna plant - loss of octane number from aromatic hydrogenation of impurities in the feedstock, notably nitrogen compounds, followed by a hydrocracking step. In 1939, ICI developed the second-stage catalyst for a plant that contributed largely to Britain's supply of aviation gasoline in the subsequent years. | |||
During World War II, two stage processes were applied on a limited scale in Germany, Britain and USA. In Britain, feedstock were creosote from coal tar and gas oil from petroleum. In the USA, Standard Oil of New Jersey operated a plant at Baton Rouge, producing gasoline from a Venezuelan kerosine/light gasoil fraction. Operating conditions in those units were comparable: approximate reaction temperature 400 0C and reaction pressures of 200-300 bar. | |||
==References== | ==References== | ||
{{reflist}} | {{reflist}} | ||
Revision as of 16:15, 18 July 2009
Hydrocracking is a catalytic process used in petroleum refineries for converting the high-boiling constituent hydrocarbons in petroleum crude oils to more valuable lower-boilng products such as gasoline, kerosene, jet fuel and diesel oil. The process takes place in a hydrogen-rich atmosphere at elevated temperatures (260 – 425 °C) and pressures (35 – 200 bar).[1][2][3]
Basically, the process cracks the high-boiling, high molecular weight hydrocarbons into lower-boiling, lower molecular weight olefinic and aromatic hydrocarbons and then hydrogenates them. Any sulfur and nitrogen present in the hydrocracking feedstock are, to a large extent, also hydrogenated and form gaseous hydrogen sulfide (H2S) and ammonia (NH3) which are subsequently removed. The result is that the hydrocracking products are essentially free of sulfur and nitrogen impurities.
Hydrocracking plants are capable of processing a wide variety of feedstocks of different characteristics to produce a broad range of products. They can be designed and operated to maximize the production of a gasoline blending component (called hydrocrackate) or to maximize the production of diesel oil.
History
The history of the process goes back to the later 1920s when a plant for the commercial hydrogenation of brown coal was commissioned at Leuna in Germany. Tungsten sulphide was used as a catalyst in this one-stage unit , in which high reaction pressures, 200-300 bar, were applied. The catalyst displayed a very high hydrogenation activity: the aromatic feedstock, coal and heavy fractions of oil, containing sulphur, nitrogen and oxygen, was virtually completely converted into paraffins and isoparaffins. The result of the Leuna plant - loss of octane number from aromatic hydrogenation of impurities in the feedstock, notably nitrogen compounds, followed by a hydrocracking step. In 1939, ICI developed the second-stage catalyst for a plant that contributed largely to Britain's supply of aviation gasoline in the subsequent years.
During World War II, two stage processes were applied on a limited scale in Germany, Britain and USA. In Britain, feedstock were creosote from coal tar and gas oil from petroleum. In the USA, Standard Oil of New Jersey operated a plant at Baton Rouge, producing gasoline from a Venezuelan kerosine/light gasoil fraction. Operating conditions in those units were comparable: approximate reaction temperature 400 0C and reaction pressures of 200-300 bar.
References
- ↑ James H. Gary and Glenn E. Handwerk (1984). Petroleum Refining: Technology and Economics, 2nd Edition. Marcel Dekker. ISBN 0-8247-7150-8.
- ↑ Editorial Staff (November 2002). "Refining Processes 2002". Hydrocarbon Processing : pages 115 – 117.
- ↑ Naveen Bhutani, Ajay K. Ray and G.P. Rangaiah (2006). "Modeling, Simulation and Multi-objective Optimization of an Industrial Hydrocracking Unit". Ind. Eng. Res. 45 (4): pages 1354 – 1372.