“Amine modified SBA-15 and MCM-22 as high capacity CO2 adsorbents”

E. I. BASALDELLA; N. FIRPO; J.C. TARA; E.L. SOTO

Turín, Italia

Congreso; VIII AIZ Congress 2007; 2007

Associazione Italiana Zeoliti ONLUS

It is known that in many industrial processes like air separation, hydrogen production and helium extraction, carbon dioxide needs to be removed from various gas mixtures. Moreover, the increasing atmospheric CO2 concentration, mainly caused by fossil fuel combustion, has led to concerns about global warming.            Most of the CO2 emissions are derived from stationary sources pertaining to industries related to energy production. Therefore, if a cost effective and environmentally safe CO2 capture process could be successfully utilized in the energy industry, there would be substantial reductions in CO2 emissions.            New studies are exploring a number of capture technology areas, and one area of investigation involves the use of novel adsorbents. Different types of zeolites were proposed as suitable adsorbents for CO2. Additionally, amine-based absorption technology has been established for over 60 years in the chemical and oil industries, for removal of hydrogen sulphide and other acid gases from gas streams.             The purpose of this work is to develop adsorbents presenting a large volume for enhanced gas diffusion and a tailored surface functionality for improved CO2 adsorption. We synthesized two types of porous matrices: SBA-15 silica and MCM-22 zeolite. Different quantities of amine groups were incorporated to these ordered materials by post-synthesis impregnation, using hexamethyleneimine (HMI) as the amine source. SBA-15 was selected as support because of previous results reported by Xu et al. The reason for including MCM-22 matrix in our studies is due to the fact that this ordered structure is generated by using HMI as synthesis director. Our results show that the reversible CO2 adsorption capacities significantly improved upon amine incorporation for both matrices. Adsorption measurements done on amine impregnated MCM-22 showed a CO2 capacity varying from 4 to 120 mg/g at 75°C, depending on the amine content. In these samples, approximately 90% of CO2 adsorption occurred almost instantaneously, and was removed just as rapidly at room temperature with an inert gas flow.