Effectiveness of amino-functionalized sorbents for co2 capture in the presence of Hg

The reduction of CO2 emissions is an urgent need that is acknowledged worldwide. Amino-silica sorbents are one of the most promising adsorbents for capturing CO2 from several gas streams due to their excellent textural properties and reversible reactions with CO2. However, gas streams also contain impurities that can affect the retention of CO2 by such sorbents. This study focuses on the effect of the presence of mercury in the gas stream on a series of amino sorbents developed for CO2 capture. Amino-silica adsorbents were functionalized by grafting with aminopropyl-trimethoxysilane (AP) or trimethoxysilylpropyl-diethylenetriamine (DT) and by impregnation with polyethyleneimine (PEI) or tetraethylenepentamine (TEPA). A double functionalization route that combines grafting and impregnation was also assayed. The effect of mercury on the CO2 adsorption capacity of the sorbents was evaluated in a fixed reactor at 40 degrees C. The double-functionalized adsorbents showed high CO2 uptakes with CO2 adsorption capacities of 5-6 mmol CO2/g (0.15 bar CO2, 40 degrees C). In addition, their CO2 adsorption capacity was maintained over several cycles. It was established that the presence of mercury undermined the CO2 adsorption capacity of the adsorbents by just 3-16%, demonstrating in general the good selectivity of these materials for CO2, an essential requirement for avoiding the accumulation of mercury during the regeneration process of the solid sorbent and the consequent environmental and technological problems that might ensue.