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Various functions of activated carbon catalyst carrier

  • Carrie Ge
    Host
    Jan 20
    Using activated carbon as a carrier has a much wider application range than activated carbon itself as a catalyst. The carrier is the dispersant, binder and support of the main catalyst and promoter in the solid catalyst. The role of the carrier is multifaceted, which can be summarized as follows.




    1. Dispersion




    Heterogeneous catalysis is an interfacial phenomenon. Therefore, the active component of the activated carbon catalyst is required to have a sufficient surface area, which requires the dispersion of the active component to be in a micron-level or atomic-level dispersion state. activated carbon pellets manufacturer The carrier can disperse the active ingredient into very small particles and maintain its stability. For example, the precious metal Pt is loaded on the Al2O3 carrier to disperse the Pt into nano-sized particles, which becomes a highly active catalyst, thereby greatly improving the utilization rate of the precious metal.




    1. Stabilization




    The activated carbon carrier can stabilize the catalyst and prevent the microcrystals of the active component from semi-melting or recrystallization. The carrier can block the crystallites and prevent the crystallites from migrating under high temperature conditions. For example, when using aluminum/magnesium spinel as a carrier for a hydrocarbon steam reforming hydrogen production catalyst, it can prevent the active component Ni crystallites from growing at high temperatures (1073K).




    1. Supporting role




    The activated carbon support can give the solid catalyst a certain shape and size, so that it meets the requirements of industrial reactions for its hydrodynamic conditions. The activated carbon carrier can also make the catalyst have a certain mechanical strength, so that it will not be broken or pulverized during use, so as to avoid the increase of the resistance of the catalyst bed, so that the fluid distribution is uniform and the process operation conditions are kept stable.




    1. Heat transfer and dilution




    For strong exothermic or strong endothermic reactions, by selecting a catalyst carrier with good thermal conductivity, the reaction heat can be removed in time to prevent the catalyst surface temperature from becoming too high. For high-activity active components, adding an appropriate amount of activated carbon carrier can dilute and reduce the activity of the catalyst per unit volume to ensure heat balance. The two functions of the support can make the reaction temperature of the catalyst bed constant, and can also improve the thermal stability of the active components.




    1. Promotion effect




    In addition to the above-mentioned physical effects, activated carbon carriers also have chemical effects. The chemical interaction between the carrier and the active component or co-catalyst will cause changes in the activity, selectivity and stability of the catalyst. wan yang activated carbon In highly dispersed supported catalysts, the oxide support can have a strong interaction or induction effect on metal atoms or ionic active components, which will play a catalytic role. The acid and basic properties of the carrier can also produce multifunctional catalysis with metal active components, so that the activated carbon carrier also becomes a part of the active components to form a dual-functional catalyst.