Relationship between the adsorption value of molecular sieve and temperature change

*Basic relationship between adsorption value and temperature change

Studies have shown that the adsorption value of molecular sieves is closely related to the working temperature. Generally speaking, as the temperature increases, the adsorption value of molecular sieves will show a downward trend. This phenomenon is mainly attributed to two factors: 

1, the thermal motion of the adsorbate molecules intensifies, resulting in a decrease in their contact time with the adsorbent surface, thereby reducing the adsorption efficiency. 2, high temperature may reduce or inactivate the active sites on the adsorbent surface, further weakening its adsorption capacity.

Specifically, when the temperature rises, the thermal motion of the adsorbate molecules becomes more intense, and the frequency of collisions between molecules increases, making it more difficult for them to form a stable adsorption layer on the adsorbent surface. In addition, high temperature may also cause slight changes in the internal structure of the adsorbent, such as deformation of the pore structure or destruction of the active sites, which will directly affect its adsorption performance.

*Case analysis in applications

Before syngas enters the synthesis tower, molecular sieves are usually used to remove trace impurities such as CO2, CO and H2O. In this process, the adsorption performance of molecular sieves is directly related to the purity of syngas and the efficiency of subsequent reactions. Experiments show that as the inlet gas temperature increases, the outlet temperature of the molecular sieve will also rise. Although this temperature rise is not significant in most cases (generally between 1 and 2 degrees), it can still reflect the release of heat and the change in adsorption efficiency during the adsorption process.

It is worth noting that although the adsorption process itself is exothermic, the released heat is often taken away by the flowing gas, so the impact on the overall temperature is relatively limited. However, if the regeneration process of the molecular sieve is not properly controlled, such as the regeneration temperature is too high or the valve is not tightly sealed, it may cause the temperature of the molecular sieve in operation to rise abnormally, thereby affecting its adsorption performance.