Article pubs.acs.org/EF
Highly Efficient CO2 Capture to a New-Style CO2‑Storage Material Tianxiang Zhao, Bo Guo, Qiang Li, Feng Sha, Fei Zhang, and Jianbin Zhang* College of Chemical Engineering, Inner Mongolia University of Technology, Huhhot 010051, China S Supporting Information *
ABSTRACT: A highly effective and economically feasible system for capturing CO2 was developed from 1,2-ethanediamine (EDA) + polyethylene glycol 300 (PEG), in which CO2 was activated and directly transformed to a novel solid CO2 storage material (CO2SM) under mild conditions. The essence of CO2SM is alkylcarbonate salt, and the potential applications of CO2SM would take advantage of elemental nitrogen to boost the growth of plants.. In addition, the EDA + PEG aqueous solution could be recycled multiple times without significant loss in its ability to capture and release CO2. Thus, the process offered an alternative way for comprehensive utilization of CO2 and potentially enables the CO2 conversion to a value-added chemical.
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was in good agreement with the previously reported data.26 However, one of the major drawbacks is the significant loss of amine during the EDA regeneration. Therefore, we searched for an amine-fixing agent, which could effectively control the volatilization of EDA in the absorption and thermal regeneration processes of CO2. Our previous work27 suggested that PEG had multiple hydrogen bond sites and could form hydrogen bonds with EDA, and the thermal stability of EDA and equimolar EDA + PEG system also indicated that the addition of PEG could create an amine-fixing agent to reduce the volatility of EDA (see Figure S1 in the Supporting Information). Previously, Sengwa28 reported the hydrogen bond interactions and hydrogen bonded structures in aminealcohol mixed solvents could decrease the loss of amine. Park29 also found that amandine with an alcoholic moiety could effectively reduce the volatility of solution. Above all, the equimolar EDA and PEG system was developed to uptake, store, and convert CO2 to CO2SM. The flowchart of CO2 capture and comprehensive utilization is shown in Figure 1. Here, PEG was used as an amine-fixing agent to efficiently reduce the EDA loss and significantly improve the absorption performance of CO2; meanwhile, resource utilization of CO2SM was realized by the preparation of quick-acting fertilizer.
INTRODUCTION Atmospheric concentration of greenhouse gasesspecifically, CO2has been increased significantly, because of anthropogenic industrial activities.1 In order to control the CO2 level worldwide, efficient reduction (capture and utilization) of CO2 discharged from industrial processes has become one of the urgent and biggest challenges in the 21st century.2,3 Currently, CO2 capture and storage/sequestration (CCS) and CO2 capture and utilization (CCU) are still the two main approaches to reduce CO2.4−8 In CCS, CO2 is captured into absorbents through absorption,9,10 adsorption,11 or membrane separation technology,12 and then stored deep underground.13 For example, with numerous liquid primary and secondary amines, such as monoethanolamine (MEA) and diethanolamine (DEA), CO2 is chemically converted to carbamic acids or corresponding ammonium carbamates, then the dehydration of ammonium carbamates generates substituted ureas and the fixed CO2 is released upon heating.14,15 Through the use of tertiary amine aqueous solution, such as N-methyldiethanolamine (MDEA), CO2 can form bicarbonate.16 However, these amine-based technologies still have their major drawbacks, including the corrosive nature and volatility of amines, decomposition of the generated salts, and high regeneration energy cost.17,18 In comparison with CCS, CCU is more attractive, because it can not only consume CO2, which ultimately affords an environmentally friendly C1 feedstock, but also produce valueadded chemicals,19,20 such as fuels, commodity chemicals, construction materials, and mineral carbonates.21,22 However, the biggest obstacle to the CCU approach lies in the highest oxidation state of carbon, so that the approach requires reaction with certain high-energy substances or electroconductive processes to chemically activate CO2.23 Recently, Heldebrant and his co-workers24,25 reported a series of CO2 binding organic liquids (CO2BOL) based on alcohols and amidine (or guanidine) superbases, which could convert CO 2 into ammonium or guanidinium alkylcarbonate salts. However, these systems are still too expensive to apply in industry. In this work, it was found that 1.00 mol of EDA could absorb 0.4672 mol of CO2 in EDA-based CO2 capture process, which © XXXX American Chemical Society
2. EXPERIMENTAL SECTION 2.1. Materials. The analytical-grade EDA was purchased from Tianjin Reagent Company (Tianjin, China; residue on ignition, ≤0.1%). The analytical-grade PEG with the average molecular weight of 300 (280−310) was purchased from Beijing Reagent Company (Beijing, China; ≥95.0% purity). They were used after drying over 4 Å molecular sieves and ultrasound desecrating just before the experiment. Doubly distilled water with a conductivity of
