Abstract:
The amine modified fumed silica sorbent appears to be a promising approach to adsorb CO2 and H2S from biogas. In this study, the amine (Polyethyleneimine (Mw. 800) or PEI800, this amine is considered in previous research that it has a good efficiency to adsorb CO2 and H2S) modified fumed silica sorbent pellets were prepared by using an extrusion method with various types and amounts of binders. The three chosen binders for the study were starch, polyvinyl alcohol (PVA) and bentonite clay. The effects of variables, amounts and types of binders on CO2 and H2S adsorption and mechanical strength, that decrease pressure drop in the system, were investigated. The results showed that amine modified fumed silica with bentonite clay binder (Fsi-PEI800-40/Bentonite) gave the highest CO2 and H2S adsorption. Amine modified fumed silica with PVA binder (Fsi-PEI800-40/PVA) gave the highest mechanical strength with CO2 and H2S adsorption value slightly lower than amine modified fumed silica with bentonite clay and starch binder. For adsorption in 2 column in series (1st and 2nd column at 80๐C and 30๐C, respectively), amine modified fumed silica with PVA binder gave a CO2 breakthrough and saturation capacity of 1.075 and 1.407 mmol/g-sorb and a H2S breakthrough and saturation capacity of 0.017 and 0.018 mmol/g-sorb, respectively. This result indicated that the amine modified fumed silica with good mechanical strength (0.892 MPa) are effective for removing carbon dioxide and hydrogen. Moreover, amine modified fumed silica with PVA binder had good regenerability and stability with repeating adsorption desorption cycles. Thus, this adsorbent pellet has high potential to be used as CO2 and H2S sorbent in large scale packed bed.