Microwave-synthesized high-performance mesoporous SBA-15 silica materials for CO 2 capture
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pISSN: 0256-1115 eISSN: 1975-7220
INVITED REVIEW PAPER
INVITED REVIEW PAPER
Microwave-synthesized high-performance mesoporous SBA-15 silica materials for CO2 capture Runa Dey and Arunkumar Samanta† Department of Chemical Engineering, Indian Institute of Technology (ISM), Dhanbad - 826004, Jharkhand, India (Received 8 November 2019 • Revised 14 May 2020 • Accepted 31 May 2020) AbstractMicrowave-assisted post-synthetic detemplating method was applied to remove successfully the occluded organic template from the mesoporous silica frameworks of as-synthesized SBA-15 within a short period of time compared to a conventional method, such as furnace calcination. The nitrogen adsorption/desorption isotherm studies showed that the resultant detemplated SBA-15 had a very high specific surface area of 1,271 m2/g, large pore size of 9.21 nm and high pore volume of 2.10 cm3/g; while the powder X-ray diffraction patterns and high-resolution TEM images of these support materials revealed the presence of highly ordered mesopores without any structural shrinkage. Both the microwave power and time during post-synthetic microwave irradiation were found to influence the morphological structure of the SBA-15 support. To evaluate the adsorption performance of the microwave-irradiated SBA-15 support, CO2 adsorption uptake was measured after functionalizing it with different loadings of polyethyleneimine (PEI) under 9.7% CO2/N2 mixture at 75 oC. The maximum CO2 uptake was 3.63 mmol CO2/g (0.16 g/g), with an optimum PEI loading of 70 wt%. Because of the significant improvement in structural characteristics, the microwave-irradiated SBA-15 supports facilitated more PEI incorporation that contributed to about 15% higher CO2 uptake than that of conventional furnace calcined one. In addition, the sorbent demonstrated very good cyclic stability when tested over 25 cycles and for a total duration of 20 h in humid conditions. Keywords: SBA-15, Microwave, Detemplation, Calcination, Multicycle
silica supports. SBA-15 supports have attracted much attention because of their large surface area, pore volume in comparison with other silica templated supports. Ahn and co-workers [17] compared the performance of different silica supports, such as MCM-41, SBA15, and concluded that the pore diameter and pore arrangement of mesoporous silica materials reasonably influence the CO2 sorption performance. Similar observations have also been reported [18,19]. Chen et al. [18] reported the outstanding performance of the PEI impregnated silica monolith that exhibited a multimodal hierarchical pore structure. It showed CO2 adsorption capacity as high as 3.75 mmol CO2/g under 5% CO2/N2 at 75 oC. This was attributed to the high pore volume of the monolith that can accommodate a larger amount of amine. Chen et al. [19] also found that the pore volume and pore size of the synthesized silica from power plant bottom ash was larger than conventionally synthesized SBA-15 and obtained equilibrium CO2 adsorption capacity of 3.32 mmol CO2/g with 60 wt% PEI. However, the ef
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