The objective of the present study is to develop a new type of “molecular basket” sorbent (MBS) by using inexpensive and commercially available carbon materials instead of mesoporous silica molecular sieves as supports for CO2 capture from flue gas. Several commercial carbon materials, including activated carbons and carbon blacks, with different pore sizes and pore volumes have been used to prepare the carbon-based MBS (CB-MBS) by loading the CO2-philic polyethylenimine (PEI) on them. The CO2 sorption performance of the prepared CB-MBS was evaluated by using a thermogravimetric analyzer and a fixed-bed flow sorption system. Effects of the pore properties of the carbon supports, PEI loading amount, sorption temperature, and moisture on the sorption capacity were examined. A sorption capacity of 135 mg-CO2/g-sorb was obtained by loading 50 wt % PEI on a carbon black, which is almost the same as that of PEI(50)/SBA-15 prepared by loading 50 wt % PEI on SBA-15. The higher CO2 sorption capacity of 154 mg-CO2/g-sorb was achieved when increasing the PEI loading on the carbon black to 65 wt %. Characterization of the porous structure of the carbon materials indicates that the high sorption capacity of the carbon-black-supported PEI sorbents can be ascribed to their high pore volume and large pore size. It was further found that the volume-based capacity of PEI(50)/C4 was even higher than that of PEI(50)/SBA-15 by 57% due to the higher packing density (0.35 g/mL) of the former than that (0.22 g/mL) of the latter. Because of its high CO2 sorption performance and low preparation cost, the carbon-based MBS could be a promising sorbent for cost-efficient CO2 capture from flue gas.

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The continuous rise of the atmospheric CO 2 concentration and its linkage with climate change demand an urgent technological solution to reduce CO 2 emissions. 1 Carbon capture and sequestration (CCS) have been considered as one of the key options for mitigating CO 2 emissions. 2 On the basis of the current technology (amine scrubbing), the CCS cost is very high, in which the CO 2 capture from the sources was estimated to be two-thirds or even more of the total costs for CCS. 3,4 Consequently, many research approaches have been carried out for the development of novel technologies to reduce the cost for the CO 2 capture. Among all of these research efforts, the CO 2 capture by adsorption/sorption on the immobilized amine sorbents has been considered as one of the most promising approaches. [4][5][6][7][8][9] In our previous studies for CO 2 capture, we have developed the novel sorbents, called as the "molecular basket" sorbents (MBSs), which were prepared by immobilizing CO 2 -philic polyethylenimine (PEI) on silica mesoporous molecular sieves. [10][11][12] The second generation of MBS (MBS-2) prepared by loading 50 wt % PEI on SBA-15 showed a CO 2 capacity as high as 140 mg of CO 2 /g of sorbent at a CO 2 partial pressure of 15 kPa, because the MBS increases the total density of the accessible amine functional groups on/ in the sorbent. [13][14][15] In addition, the MBS has also some other significant potential advantages, including high selectivity for CO 2 , no or less corrosion problem, high sorption/desorption rate because of high gas-sorbent interface area (∼80 m 2 /g), positive effect of moisture on the MBS performance, and lower energy consumption during regeneration. However, the support materials currently used in the preparation of the

A high-performance adsorbent, CDA-C2, has been prepared from lignite by a chemical activation method with NaOH as an activation agent for removing nitrogen compounds from liquid hydrocarbon streams. The effects of coal ranks, activation agents (NaOH, KOH, NaOH + KOH, or H 3 PO 4 ), and activation methods (chemical and physical) on the adsorptive denitrogenation (ADN) performance of the coal-derived adsorbents (CDAs) were examined. ADN performance of the prepared CDAs was evaluated in a batch system using a model diesel fuel and in a flow adsorption system using a real coal liquid with a total N content of 980 ppmw. It was found that CDA-C2, which was prepared from a lignite by chemical activation using NaOH as an agent at 650 °C for 1 h with a yield of 47.8 wt %, gave a saturation capacity of 1.73 mmol of N/g of adsorbent for ADN of the real coal liquid, which is about 6 times higher than that of the best commercial activated carbon adsorbent. The higher ADN capacity and selectivity of CDA-C2 can be attributed to its significantly higher oxygen-containing functional groups (12 mmol/g of adsorbent) on the surface, as revealed by temperature-programmed desorption (TPD) analysis. In addition, the spent CDA-C2 can be regenerated by the toluene washing at 80 °C, followed by heating at 200 °C. On the basis of the present study, a new conceptual process for denitrogenation of liquid hydrocarbon streams was proposed, which can be operated at ambient conditions without using H 2 gas.

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