Reaction Technology and Regeneration Principle of Propane Dehydrogenation (PDH) to Propylene

The dehydrogenation of propane to propylene is to produce propylene by removing hydrogen gas from propane under the action of catalyst.

Compared with the pyrolysis reaction, the use of dehydrogenation catalyst reduces the activation energy of the propane dehydrogenation reaction, so that the dehydrogenation reaction can take place at a lower temperature. The reaction equations involved in the reaction process are as follows.

The dehydrogenation of propane to propylene is a highly endothermic and reversible reaction with increasing molecular number. The conversion rate depends on thermodynamic equilibrium.

In order to make the reaction proceed in the direction of dehydrogenation, it needs to be carried out under the conditions of high temperature and low pressure. However, when the temperature is too high, C-C bond is more likely to break than C-H bond, resulting in deep cracking and deep dehydrogenation of propane, aggravating side reactions and increasing by-products. Moreover, high temperature will accelerate the coking of the catalyst surface, leading to the deactivation of the catalyst.

The causes of catalyst deactivation include loss of active components, carbon deposition, catalyst poisoning, catalyst sintering, deposition of by-products, etc.

The catalyst may be sintered at high temperature, and the metal grains in the supported metal catalyst grow on the surface of the support, resulting in the reduction of catalyst activity.

With the increase of the reaction temperature and the decrease of the space speed, the propane conversion rate also increases, but the propylene selectivity decreases gradually. Under the conditions of 600℃ reaction temperature and 400h-1 space velocity of propane, the conversion of propane is 43.41%, the selectivity of propylene is 81.29%, and the yield of propylene is 35.29%.