Ujjenia Project on Catalysis of Hydrocracking and Hydro Treating''

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GajendraUjjenia
Rajiv Gandhi Institute of Petroleum Technology

Catalysis in Hydrotreating and
Hydrocracking

By:- Gajendra Ujjenia
Rajiv Gandhi Institute of Petroleum Technology
Abstract:-
Hydroprocessing is used in the petroleum refinery to crack larger molecules and/or to remove S, N and metals from petroleum derived feed stocks such as, gas-oil and heavy oil. Hydrocracking is a process in which higher hydro carbons are converted into smaller hydrocarbon .The rate of cracking depends on several factors like temperature ,catalyst. Its main objective is to remove feed contaminants and to convert low value gasoil to valuble products.Purpose of hydrocracking severe form of hydroprocessing is to break carbon-carbon bonds and drastic reduction of molecular weight.Products more appropriate for diesel than gasoline. Hydrotreating is a process in which nitrogen,sulfar and other hetro atomic compounds. Metals such as nickel and vanadium may be removed from the hydrocarbon stream during hydrotreating. Hydrotreaters may be designated to continuously process one particular hydrocarbon feedstock, or may alternate processing of different feed streams.In other words hydrotreating is a refinery process in which hydrogen gas is mixed withthe hydrocarbon stream and contacted with a fixed-bed of catalyst in a reactorvessel at a sufficiently high enough temperature and pressure to effect the hydrodesulfurization (HDS) reactions. In the HDN reaction, the bond between the carbon and nitrogenatoms is broken, and the nitrogen atom is replaced with a hydrogen atom. Hydrotreating process conditions range from the relatively mild reactor conditions of as low as 400 psi and 500°F for naphthas to very severe conditions of up to 2,000 psi and 800°F for heavy gas oils and vacuum residuum. The major catalysts used in the catalysis of hydrotreating and hydrocracking are SENTRY MAX Trap[As], SENTRY MAX Trap[Si], CENTRA DC-2618, CENTRA DC -3630, ASCENT DC- 2513, ASCENT DC-2532, ASCENT DC-2534, ASCENT DN-3531, CENTINEL GOLD DN-3330

Introduction:-
A catalyst accelerates a chemical reaction. It does so by forming bonds with the reacting molecules, and by allowing these to react to a product, which detachesfromthe catalyst, and leaves it unaltered such that it is available for the next reaction.Infact, we can describe the catalytic reaction as a cyclic event in which the catalystparticipates and is recovered in its original form at the end of the cycle. A catalyst offers an alternative, energetically favorable mechanism to the non-catalytic reaction, thus enabling processes to be carried out under industrially feasible conditions of pressure and temperature. In petroleum geology and chemistry, Commercial hydrocracking catalysts comprise active metals on solid, highly acidic supports. The active metals are Pd, Ni, Mo or Ni, W, all of which catalyze both hydrogenation and dehydrogenation reactions. The most common supports are synthetic crystalline zeolites and amorphous silica aluminas. Hydrocracking catalyst shapes can be spherical or cylindrical, with gross dimenssions similar to those for hydrotreating catalysts. As already mentioned, in most hydrocrackers, the first...
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