Adsorption–Desorption Behaviors of Methanol and Ethyl Acetate on Silica Gel: Modeling and Experimental Tests

Methanol and ethyl acetate are typical oxygen-containing volatile organic compounds which are widely used in industry, often leading to serious pollution. Herein, the adsorption–desorption hybrid process has been applied to recover and recycle the methanol and ethyl acetate waste gases using micro–mesoporous silica gel. Results show that compared with commercial activated carbons, the silica gels perform better (85%) in adsorbing the methanol and ethyl acetate due to their stronger affinity. Further tests show that competitive adsorption happens between them. The silica gel shows stronger affinity to ethyl acetate than to methanol. It is also found that an increase in the flow rate and concentration could facilitate the mass transfer of the substances in the pores of the silica gels. Based on the tests, an adsorption process simulation method with ideal adsorption solution theory and the linear driving force model has been applied to simulate the overshoot behaviors of breakthrough curves for the dynamic adsorption of this binary mixture on silica gels (error in ±7%). In this way, the concentration distribution of each adsorbed component on the solid phase in the adsorption bed has also been visualized and analyzed, which was validated by experimental tests. A dynamic adsorption model has been proposed to describe the adsorbed multicomponents on the solid phase for the adsorption of mixture. Finally, according to the adsorption and desorption profiles, a temperature swing–pressure swing combined process is proposed to desorb the adsorbed methanol–ethyl acetate mixture.