Is the hydrogenation of anthracene oil and coal tar carried out via gas-phase hydrogenation or liquid-phase hydrogenation?
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As the title suggests, is it the reaction of liquid anthracene oil (or coal tar) with gaseous hydrogen, or is it the reaction of gaseous anthracene oil (or coal tar) with gaseous hydrogen?
They all have them! Hydrogenation is divided into fixed-bed, moving-bed, fluidized-bed, and suspended-bed types
Since it’s not clear what specific aspect you would like to know about, your question needs to be answered from two perspectives: First, from a purely professional standpoint, the hydrogenation of anthracene oil or coal tar definitely takes place in a gas-phase environment, as both types of oils belong to heavy distillates with high degrees of unsaturation; the hydrogen consumption is generally around 5%, and it’s difficult to carry out this process in a pure liquid-phase setting. Here, I need to explain the difference between gas-phase hydrogenation and liquid-phase hydrogenation. Gas-phase hydrogenation involves a gas phase as the continuous phase, that is, hydrogen gas; it requires a recycle compressor, and the material (oil) partially vaporizes – not necessarily completely. Most common hydrogenation units use gas-phase hydrogenation. Liquid-phase hydrogenation involves a liquid phase as the continuous phase; in other words, the reactor is filled entirely with liquid, and hydrogen is injected and dissolved in the oil. The hydrogen dissolved in the oil is then dissociated through oil circulation to carry out the hydrogenation process. For example, the diene selective hydrogenation unit; the most prominent feature of this type of hydrogenation unit is the absence of a recycle hydrogen system. Secondly, from a non-professional perspective, if you are asking about the state of anthracene oil or coal tar in a reactor, I can tell you with certainty that it exists in a two-phase state of gas and liquid. Since the actual boiling points and distillation dry point temperatures of anthracene oil or coal tar are around 500 degrees Celsius, the maximum temperature in a hydrogenation reactor generally does not exceed 400 degrees Celsius (with most operations being controlled at below 380 degrees Celsius). Moreover, the reaction temperature is usually kept low at first and then increased, so it is not possible to achieve complete vaporization of the oil.