A Novel Mesoporous SiO₂ Material with MCM-41 Structure from Coal Gangue: Preparation, Ethylenediamine Modification, and Adsorption Properties for CO₂ Capture

Abstract

A novel mesoporous SiO2 material (M-SiO2) with MCM-41 structure was readily fabricated from the inexpensive coal gangue via a hydrothermal reaction in the presence of cetyltrimethylammonium bromide (CTAB) for CO2 capture. On the basis of orthogonal experimental results, the optimum conditions for the preparation of M-SiO2 were identified as follows: the SiO3 2– leaching of 21 g/L from coal gangue, the CTAB concentration of 0.25 mol/L, the HCl concentration of 2.5 mol/L, the hydrothermal temperature of 393.15 K, and the hydrothermal time of 20 h. Under the optimum condition, the M-SiO2 exhibited an adsorption capability of 9.61 mg/g to 8% CO2 at 298.15 K. To further improve the CO2 adsorption performance, the M-SiO2 was chemically modified using ethylenediamine (EDA), and the optimum conditions for the modification of M-SiO2 were identified as follows: the impregnation time of 10 h, the drying temperature of 343.15 K, and the ratio of EDA/M-SiO2 = 2:1. Under the optimum conditions, the adsorption capability of EDA-modified M-SiO2 (EDA-M-SiO2) was increased by 83.5 mg/g. The obtained M-SiO2 and EDA-M-SiO2 were systemically characterized by N2 adsorption–desorption isotherms, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements techniques. The analytical results indicated that the M-SiO2 was mainly composed of O and Si in the form of SiO2 with a specific surface area of 156 m2/g, and part of M-SiO2 exhibited a structure similar to MCM-41. Moreover, the mechanisms of EDA modification and CO2 adsorption were investigated and discussed in detail.

Flowing-Air-Induced Transformation to Promote the Dispersion of the CrOx Catalyst for Propane Dehydrogenation

“…As we known that the main method for avoiding the aggregation of the Cr species is decreasing the loading of Cr because the high Cr loading in the catalysts easily leads to the aggregation of the Cr species. 30,31 However, when we chose a high loading of 10% and even 20 wt %, the diffraction intensity of α-Cr 2 O 3 could still be significantly decreased, demonstrating that the flowing air treatment greatly promoted the dispersion of Cr/MCM41. Here, we provide a simple and effective method to promote the dispersion of the Cr species at both low and high loadings.…”

Synthesis of zeolite A with high whiteness from coal gangue by two‐step pretreatment method

“…After the slurry is stratified, the samples were retained for magnetic separation and dried. The Fe removal rate by magnetic separation (R Fe2O3, M ) was calculated according to Equation (1).…”

“…Coal gangue (CG) is a solid waste generated in the coal mining and washing process, 1 accounting for about 10%–15% of the total coal production 2,3 . The bulk accumulation of CG has caused serious waste of resources and environmental pollution 4,5 .…”

Preparation of NaA Zeolite from High Iron and Quartz Contents Coal Gangue by Acid Leaching—Alkali Melting Activation and Hydrothermal Synthesis

“…Coal gangue is the main discharged waste of the coal industry [1,2]. The arbitrary stacking of it seriously influences the safety of the ecological environment [3,4]. Recently, the development and utilization of coal gangue as a kind of new resource has gained interest [5][6][7].…”