SBA-15 prepared via ethanol extraction for template removing was grafted with three kinds of amine precursors (mono-, di-, tri-aminosilanes) to synthesis new CO₂ adsorbents. The SBA-15 support and the obtained adsorbents were characterized by X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), N₂ adsorption/desorption, thermogravimetry (TG), elemental analysis, Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that, except higher silanol density, the ethanol-extracted SBA-15 support possessed a more regular mesophase and thicker walls than traditionally calcined samples, leading to a good stability of the adsorbent under steam treatment. The adsorption capacity of different amine-grafted samples was found to be influenced by not only the surface amine density, but also their physiochemical properties. These observations provide important support for further studies of applying amine-grafted adsorbents in practical CO₂ capture process.

Recently, amine-functionalized materials as a prospective chemical sorbent for post combustion CO₂ capture have gained great interest. However, the amine grafting for the traditional MCM-41, SBA-15, pore-expanded MCM-41 or SBA-15 supports can cause the pore volume and specific surface area of sorbents to decrease, significantly affecting the CO₂ adsorption-desorption dynamics. To overcome this issue, hierarchical porous silica with interparticle macropores and long-range ordering mesopores was prepared and impregnated with pentaethylenehexamine. The pore structure and amino functional group content of the modified silicas were analyzed by scanning electron microscope, transmission electron microscope, N₂ adsorption, X-ray powder diffraction, and Fourier transform infrared spectra. Moreover, the effects of the pore structure as well as the amount of PEHA loading of the samples on the CO₂ adsorption capacity were investigated in a fixed-bed adsorption system. The CO₂ adsorption capacity reached 4.5 mmol CO₂/(g of adsorbent) for HPS−PEHA-70 at 75 °C. Further, the adsorption capacity for HPS-PEHA-70 was steady after a total of 15 adsorption-desorption cycles.

The adsorption and activation of both CO₂ and methanol are mainly affected by the distance of the Lewis acid site, Zr⁴⁺, and Lewis base, Zr⁴⁺/O²⁻, of the Zr-based catalysts. In this paper, Zr-incorporated SBA-15 (Zr-SBA-15) and Zr-grafted SBA-15 (Zr/SBA-15) catalysts were prepared with different Zr environments, and were analyzed with N₂ adsorption–desorption isotherms, X-ray diffraction, UV-vis spectra, and XPS. It was proposed that Zr-SBA-15 catalyst with Si-O-Zr-OH and Zr-O-Si-OH structure exhibited non-adjacent sites between Zr⁴⁺ and Zr⁴⁺/O²⁻, while Zr/SBA-15 catalyst with Zr-O-Zr-OH structure showed neighboring sites between Zr⁴⁺ and Zr⁴⁺/O²⁻. Furthermore, the Zr/SBA-15 catalyst exhibited good catalytic activity, while no DMC was detected over the Zr-SBA-15 catalyst at the same reaction conditions. For combined in situ infrared and catalytic performance, it was indicated that the methanol and CO₂ could be activated to form DMC, only when the Zr⁴⁺ and Zr⁴⁺/O²⁻ sites existed and were adjacent to each other in the Zr-O-Zr-OH of Zr/SBA-15 catalyst.

As a byproduct of the coal gasification process, a large amount of coal gasification slag is generated. The failure to fully dispose of it has caused the occupation of land resources and environmental pollution. Before its comprehensive utilization, the carbon and ash constituents must be separated, for which flotation is an effective method. However, the small difference in surface hydrophobicity of them cannot result in a high-efficiency separation. Therefore, a colliding flow pulp conditioning device (CFPCD) was proposed in this work to improve the interaction between the collector droplets and fine particles, and strengthen the modification of collector on the particle surface by generating a properly constructed turbulent flow field. Computational fluid dynamics (CFD) was employed to simulate the internal flow field of CFPCD to obtain the critical flow field parameters, such as the velocity, strain rate, turbulent kinetic energy, turbulent dissipation rate, and turbulent eddy scale. Additionally, particle wrap angle measurements and flotation tests were conducted to verify the performance of pulp conditioning. The results showed that a velocity gradient was obvious in the inner cylinder colliding flow area, thereby inducing the large strain rate and the intense turbulence, which were responsible for the pulp homogenization and the enhanced particle-collector interaction. With the feeding velocity increased, the fluid shear was larger and the improved performance was more obvious. According to the flotation results, the maximum recovery of unburned carbon was obtained with the feeding velocity equal to 2.5 m/s, which was consistent with the tendency of wrap angle. Meanwhile, the loss on ignition of the tailings reached the optimal value, corresponding to 9.94%.

Alkyl-grafted 13X adsorbents display steady CO ₂ adsorption performance under humid flue gas conditions.