Mohammad R M Abu Zahra
Masdar Institute of Science and Technology, UAE
Title: Amino-functionalized mesoporous silica-based adsorbent for CO2 post-combustion capture
Biography
Biography: Mohammad R M Abu Zahra
Abstract
Conventional method capturing CO2 using amine solution has been well-known and practiced in natural gas purification for long time, but it involves high energy demand, corrosion and degradation and not suitable to capture CO2 from industrial sources like power plant flue gas. Amino-functionalized mesoporous silica adsorbent has emerged as a promising material for CO2 post-combustion capture due to its possible reduction in regeneration energy, cheap price and ease to produce at large scale. Different types of adsorbents have been prepared by impregnating amines or grafting amino functional groups on inexpensive mesoporous silica and tested for CO2 capture. Polyethyleneimine impregnated mesoporous silica (PEI-MPS) possesses high CO2 loading (above 11 mg/g), it is easy to be produced at large scale and stable for multiple adsorption/regeneration cycles operating in a packed bed reactor. It lost only 16.6% CO2 loading after 335 adsorption/regeneration cycles at 65/120 oC, respectively. At high temperature, PEI-MPS encounters the vaporization of PEI causing a quick degradation, particularly in fluidized bed reactor. Amino-functionalized mesoporous silica (APTES-MPS) is synthesized by grafting method, in which, amino-functional groups form a chemical bond to silica substrate through Si-O-Si bridges. Thanks to the chemical bonding, APTES-MPS is more thermally and mechanically stable; it starts degradation at 205 oC. Even though, the CO2 loading of this adsorbent (~80 mg/g) is lower than that of PEI-MPS, it may be suitable for CO2 capture using fluidized bed reactor. Recent study indicated that the use of PEI-MPS for CO2 capture reduced ~46% regeneration energy in comparison with conventional 30% ethanolamine solution. This is due to the low heat capacity of solid adsorbent (~2.2 J/oC) and the avoidance of water vaporization. Mesoporous silica is produced using sodium silicate; cheap silica precursor therefore resulting amino-functionalized mesoporous silica could be inexpensive and suitable CO2 capture. Highly stable adsorbent with significant reduction in energy consumption is a basis for an advanced CO2 capture process.