What is the difference between hydrorefining and hydrocracking?

Refining means desulfurization, while modification means increasing the cetane number.

In terms of modification, the high aromatic content in diesel can be used to produce high-octane gasoline.

Hydroprocessing is one of the most important refining methods for petroleum products. It refers to the process of converting harmful impurities such as sulfur, oxygen, and nitrogen in oils into corresponding hydrogen sulfide, water, and ammonia under hydrogen pressure and in the presence of a catalyst, thereby removing these impurities. It also involves the hydrogenation of olefins and dienes to saturate them, as well as the partial hydrogenation of aromatics, in order to improve the quality of the oils. Sometimes, hydrorefining refers to the refining and modification of light oils, while hydrotreating refers to the refining and desulfurization of heavy oils. The main purpose is to modify the oil products, improve their stability and extend the service life of equipment such as engines, while reducing environmental pollution. The typical reaction conditions for this process are: pressure of 4–8 MPa, and temperature of 320–400°C.

The main reactions in hydrorefining are hydrodesulfurization, hydrodenitration, hydrodeoxygenation, saturated hydrogenation of olefins and aromatics, and hydrometallurgy. The modification reaction is used to increase the cetane number, which is an important indicator of the combustion performance of diesel. Among diesel fractions, alkanes have the highest cetane number, followed by naphthenes, while aromatics have the lowest cetane number. Among hydrocarbons of the same type, those with a low degree of isomerism for the same number of carbon atoms have a higher cetane number, while hydrocarbons with a large number of aromatic rings have a lower cetane number. Therefore, diesel with a low content of cyclic hydrocarbons and a high content of linear hydrocarbons has a higher cetane number. For the bicyclic and tricyclic aromatics in catalytic diesel (LCO), during the MCI process, aromatics with more than two rings undergo only aromatic ring saturation and naphthenic ring opening, with no change in the molecular carbon count. Since bicyclic and tricyclic aromatics are converted into alkylbenzenes, the components with a high cetane number in diesel increase, thereby allowing the cetane number of diesel to be improved significantly.

The main reactions in hydrorefining are hydrodesulfurization, hydrodenitration, hydrodeoxygenation, saturated hydrogenation of olefins and aromatics, and hydrometallurgy. Hydroprocessing is primarily used to increase the cetane number of diesel, as well as to reduce its freezing point and density.

Refining in the first reactor, modification in the second reactor; there is solidification reduction

This post was last edited by uyouu1 on 2015-10-27 08:42. In short: modification actually falls under the category of cracking; those with experience in hydrocracking will understand this better.

The nature of the reactions that occur is different; refinement primarily involves removing impurities such as sulfur, chlorine, nitrogen, and oxygen, whereas modification aims to increase the cetane number by breaking chains or opening rings

1. Hydrorefining: The main reactions in hydrorefining include hydrodesulfurization, hydrodenitration, hydrodeoxygenation, saturated hydrogenation of olefins and aromatics, as well as hydrodemetallization. 2. Modification reaction: This is aimed at increasing the cetane number, which is an important indicator of the combustion performance of diesel. Among diesel fractions, alkanes have the highest cetane number, followed by naphthenes, while aromatics have the lowest cetane number. Among hydrocarbons of the same type, those with a low degree of isomerism for the same number of carbon atoms have a higher cetane number, while hydrocarbons with a large number of aromatic rings have a lower cetane number. Therefore, diesel with a low content of cyclic hydrocarbons and a high content of linear hydrocarbons has a higher cetane number. 3. Hydrocracking: It is a processing method in which, under high pressure and temperature conditions, hydrogen acts as a catalyst to induce hydrogenation, cracking, and isomerization reactions in heavy oils, converting them into lighter oils (such as gasoline, kerosene, diesel, or raw materials for catalytic cracking and pyrolysis to produce olefins). What sets it apart from catalytic cracking is that hydrocracking involves hydrogenation reactions of hydrocarbons simultaneously. The yield of liquid products from hydrocracking exceeds 98%, and their quality is also much higher than that of products obtained through catalytic cracking. Although hydrocracking has many advantages, it is not as widely used as catalytic cracking due to the demanding operating conditions required – high pressure, the need for specialized alloy steels, significant hydrogen consumption, and high investment costs.