Effect of the amine type on thermal stability of modified mesoporous silica used for CO 2 adsorption Alexandru Popa 1 • Viorel Sasca 1 • Orsina Verdes 1 • Mariana Suba 1 • Paul Barvinschi 2 Received: 29 November 2017 / Accepted: 29 May 2018 Ó Akade ´miai Kiado ´, Budapest, Hungary 2018 Abstract In this study, the preparation by grafting of amino-functionalized SBA-15 molecular sieves was carried out. Amino- functionalized molecular sieves were synthesized using a silane coupling agent and different types of amination reagents which react with modified SBA-15. These composites were characterized by FT-IR spectroscopy, X-ray diffraction at low angles, nitrogen physisorption at 77 K, and evaluated by the adsorption of CO 2 and its temperature-programmed des- orption—TPD. Thermal stability was investigated by TGA and DTA methods. In the view of a possible use of these amino- functionalized molecular sieves as sorbents for CO 2 removal, their adsorption–desorption properties towards CO 2 were also investigated by the TPD method. The mass loss of amino-functionalized molecular sieves above 215 °C was due to the oxidation and decomposition of amino propyl functional groups. This means that these composites could be used for adsorption of CO 2 at temperatures below 215 °C. The adsorption of CO 2 and its temperature programmed desorption using thermogravimetry were studied for amino-functionalized molecular sieves at 60 °C. The evolved gases during the adsorption–desorption of CO 2 on amino-functionalized molecular sieves were identified by online mass spectrometry coupled with thermogravimetry. CO 2 adsorption isotherms of functionalized samples at 60 °C showed that both the adsorption capacity (mg CO 2 /g adsorbent) and the efficiency of amino groups (mol CO 2 /mol NH 2 ) depend on the type of amination reagents and the amount of organic compound used. Keywords SBA-15 molecular sieves Á Amine Á Thermal stability Á CO 2 adsorption Introduction Global warming resulting from the emission of greenhouse gases, especially CO 2 , has become a widespread concern in the recent years. Extensive efforts have been devoted to reducing greenhouse gas emissions, including using CO 2 capture and storage. Solid sorbents adsorption is consid- ered as a potential option for the CO 2 capture process [1–7]. In the literature, adsorption of CO 2 was investigated over a wide range of conditions on a series of mesoporous silica adsorbents comprised of conventional silica, MCM- 41 and SBA-15 molecular sieves [8–17]. Beside adsorbents, mesoporous silica SBA-15 became very attractive for a wide range of applications, for example, as supports for catalysts [18–20], for drug delivery [21, 22], in separation processes [23]. The organic/ inorganic hybrid materials which are composed of amine and mesoporous silica SBA-15 are ones of the materials used for the dry CO 2 capture method because of its high CO 2 adsorption rates. Using this type of material, the mechanical strength and good thermal stability of silica are combined with the high selectivity and adsorption capacity of amine which acts as a basic material for the Lewis acid CO 2 [24]. Different methods for modifying silica or other supports by amino groups were applied by some research groups [1, 25, 26]. They have organized supported amine adsorbents into three classes. Class 1 adsorbents are based on monomeric or polymeric amines physically loaded onto or into a support, typically porous silica. Class 2 adsorbents & Alexandru Popa alpopa_tim2003@yahoo.com 1 Institute of Chemistry Timis ¸oara, Bl.Mihai Viteazul 24, 300223 Timisoara, Romania 2 Faculty of Physics, West University of Timisoara, B-dul V. Parvan, Nr. 4, 300223 Timisoara, Romania 123 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-018-7457-7