Isosteric Enthalpy Behavior of CO2 Adsorption on Micro-Mesoporous Materials: Carbon Microfibers (CMFs), SBA-15, and Amine-Functionalized SBA-15

Abstract

The isosteric enthalpy of adsorption (∆adsh ) of CO2 in three different micro and mesoporous materials was evaluated in this work. These materials were a microporous material with functional groups of nitrogen and oxygen (CMFs, carbon microfibers), a mesoporous material with silanol groups (SBA-15, Santa Barbara Amorphous), and a mesoporous material with amine groups (SBA-15_APTES, SBA-15 amine-functionalized with (3-Aminopropyl)-triethoxysilane). The temperature interval explored was between 263 K and 303 K, with a separation of 5 K between each one, so a total of nine CO2 isotherms were obtained. Using the nine isotherms and the Clausius–Clapeyron equation, the reference value for ∆adsh was found. The reference value was compared with those ∆adsh obtained, considering some arrangement of three or five CO2 isotherms. Finally, it was found that at 298 K and 1 bar, the total amount of CO2 adsorbed is 2.32, 0.53, and 1.37 mmol g−1 for CMF, SBA-15, and SBA-15_APTES, respectively. However, at a coverage of 0.38 mmol g−1, ∆adsh is worth 38, 30, and 29 KJ mol−1 for SBA-15_APTES, CMFs, and SBA-15, respectively. So, physisorption predominates in the case of CMF and SBA-15 materials, and the ∆adsh values significantly coincide regardless of whether the isotherms arrangement used was three or five. Meanwhile, in SBA-15_APTES, chemisorption predominates as a consequence of the arrangements used to obtain . This happens in such a way that the use of low temperatures (263–283 K) tends to produce higher ∆adsh values, while the use of high temperatures (283–303 K) decreases the ∆adsh values.

Aminopropyltriethoxysilane functionalized MCM-41 and SBA-15 nanostructured materials for carbon dioxide adsorption

“…The most critical element of chemical adsorption of CO 2 involves the design and development of a suitable adsorbent, which consists of porous support onto which an amine is attached [7]. The adsorption of carbon dioxide has been studied in various mesoporous materials, including the MCM-41 and SBA-15 [8][9][10][11]. Different research groups have tried to introduce amine groups into mesoporous silicas because of their elevated surface area.…”

Tuning the hybridization and charge polarization in metal nanoparticles dispersed over Schiff base functionalized SBA-15 enhances CO2 capture and conversion to formic acid

“…S9 and Table S5 †), and judging from the proles obtained and the values, it can easily be concluded that each of them shows chemisorption properties except APTES-GLU-Ex with lowest Q st exhibiting poor CO 2 interaction. 43,44 Based on the XPS analysis, it can be concluded that synthetic conditions have been optimized to tune the hybridization of nitrogen in these materials, which facilitates efficient uptake of CO 2 .…”

Effect of Calcination Temperature and Chemical Composition of PAN-Derived Carbon Microfibers on N2, CO2, and CH4 Adsorption

“…In this work, the isosteric enthalpy of adsorption has been calculated indirectly, that is, by using adsorption isotherms at different temperatures. It has been reported that when the process is dominated by physisorption, the temperatures selected for the analysis do not have much influence if the difference between them is not larger than 20 °C [ 43 ]. Five temperatures have been considered (−10, 0, 10, 20, and 30 °C).…”