Compared with other types of adsorbents, solid adsorbents prepared from amine-modified porous materials have good industrial application prospects. The current problem is that the adsorption capacity is low, and its cycle stability is poor. In this paper, LS support was synthesized using poly(ethylene oxide)-poly-(propylene oxide)-poly(ethylene oxide) (P123) as a template and sodium silicate (Na 2 SiO 3 ) as the silicon source via the partitioned collaborative self-assembly process (PCSA) and then compared to three other materials prepared by the traditional method (TS, SS, and SBA-15). CO 2 solid adsorbents were prepared by loading tetraethylenepentamine (TEPA). The structure and performance of the samples were investigated using N 2 adsorption and desorption, XRD, TEM, TG, SEM, and in-situ FTIR. Compared with the supports prepared by the traditional method, the LS prepared by the PCSA method has a larger pore size. When loaded with the same mass fraction of TEPA, LS has a higher real loading of TEPA and a better CO 2 capture performance. The effect of adsorption temperature and amine loading on the CO 2 capture performance of the adsorbent was studied. In a mixed gas (N 2 /CO 2 = 85/15) at 90 °C, the maximum CO 2 adsorption capacity of LS-TEPA70% reached 5.59 mmol/g. Furthermore, after 10 cycles of adsorption−desorption, the adsorption capacity of LS-TEPA70% was still as high as 4.87 mmol/g, which satisfies the requirements of industrial application. According to the results of in-situ infrared diffuse reflection of the CO 2 adsorption process, the TEPA loading mechanism was obtained. By analyzing the relationship between the changes in the strength of the functional groups during the reaction, a CO 2 adsorption mechanism with active sites was proposed. Under anhydrous conditions, CO 2 first combines with RNH 2 or R 1 R 2 NH, forming zwitterions. Next, the zwitterion was deprotonated, eventually forming protonated products and carbamate. This study provides a rapid method for the synthesis of large mesoporous materials and high-efficiency carbon dioxide adsorbents.
Summary
Renewable carbon materials are attractive materials with great potential for many applications. Macadamia nutshell is a by‐product of the nut industry, with high yield and fast regeneration. It is a potential precursor for biomass‐based activated carbon. In this study, we prepared an adsorbent using macadamia nutshell as a precursor and KOH as an activator. To prepare the samples with the highest CO2 uptake, the preparation process was optimized by response surface methodology (RSM). Interactions between different activation conditions were investigated, and their effects on CO2 uptake were explored. Meanwhile, visual three‐dimensional images were used to describe the effects of activation conditions and interactions on adsorption capacity. It was found that the activation conditions affected the location of the central region (high CO2 uptake region) of the carbon material. Meanwhile, the interaction between different activation conditions has a significant influence on the growth of pores during the activation process. The preparation conditions optimized by RSM in this study are as follows: activation temperature is 771°C, KOH/C is 1.7, and time is 2.3 h. At 0°C and 1 bar, the carbon sorbent prepared under optimized conditions has a CO2 adsorption capacity of 6.58 mmol/g. This study confirms that RSM is an effective method to optimize the preparation process of high‐efficiency carbon adsorbents for CO2 uptake.
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