Development of Composite Adsorbents of Activated Carbon and Hydrophobic Silica Gel for Gasoline Vapor Adsorption

A composite adsorbent with upper-layer activated carbon (TY) and lower-layer hydrophobic silica gel (HSG) was developed, based on the comprehensive consideration of both adsorption capacity and adsorption heat of activated carbon and hydrophobic silica. For the composite adsorbent, various volumetric ratio of activated carbon to silica gel was designed, and the adsorption capacity and heat effect of the composite adsorbent with different ratio were investigated. The experimental results showed that the optimum ratio was 1:1. Thus, the vapor with high concentration was early adsorbed by the lower-layer hydrophobic silica gel, and then the residual vapor with low concentration was late adsorbed by the upper-layer activated carbon. In this way, incombustibility of silica gel and high adsorption capacity of activated carbon were fully utilized; accordingly the adsorption operation safety was improved and the adsorption capacity of activated carbon was increased owing to that the activated carbon was only used to adsorb the vapor with low concentration.