• Energy Research

Abstract Protic ionic liquids (PILs) are considered as potential solvents for CO2 capture due to their simple synthetic routes and unique properties. In this work, three low viscous PILs, tetramethylgunidinium imidazole ([TMGH][Im]), tetramethylgunidinium pyrrole ([TMGH][Pyrr]) and tetramethylgunidinium phenol ([TMGH][PhO]) were synthesized and the effect of anions, temperature, CO2 partial pressure and water content on CO2 absorption performance of PILs was also systematically studied. It was found that the PILs with larger basicity show higher CO2 absorption capacity, and [TMGH][Im] simultaneously shows relatively high absorption rate and CO2 absorption capacity of 0.154 g CO2/g IL at 40 °C, 1 bar. The addition of H2O has a positive effect on gravimetric absorption capacity of CO2 at the range of 0–20 wt% H2O, and the highest capacity of 0.186 g CO2/g IL was achieved as the water content was 7 wt%. In situ FTIR, 13C NMR and theoretical calculations verified that more stable bicarbonate are produced during CO2 absorption by [TMGH][Im]-H2O system. However, neat [TMGH][Im] can react with CO2 to form the reversible carbamate, leading to excellent recyclability after four absorption-desorption cycles. The results implied that neat [TMGH][Im] shows great potentials in CO2 absorption applications.

Methanol is a future energy carrier because of its high volume-specific energy density and a significant intermediate for many bulk chemicals. Electrochemical reduction is a promising method to fabricate methanol (CH3OH) from carbon dioxide (CO2) where electrocatalyst, reactor configuration, and electrode play an essential role. In this review, seven types of electrocatalysts, that is, metal alloys, metal oxides, metal chalcogenides and carbides, metal–organic complexes, metal–free pyridine and metal–organic framework–based electrocatalysts, as well as the effect of reactor configuration and electrode were comprehensively summarized. Finally, challenges and perspectives on developing electrocatalysts were highlighted.

Quasi-solid-state lithium metal batteries are considered as one of the most promising energy storage devices, and the application of ionic liquids (ILs) as a new generation of functionalized electrolyte components in lithium metal batteries has become one of the research focuses. In this review, the very recent research work related to using ILs to develop quasi-solid-state electrolytes and their influences on the performances of quasi-solid-state lithium metal batteries were surveyed and summarized, suggesting that the introduction of ILs can improve the ionic conductivity, broaden the electrochemical stability window, and enhance the electrochemical stability of the selected electrolytes. Moreover, using ILs to prepare high-performance electrodes with unique microstructures and uniform distribution of fillers were also introduced. The composite quasi-solid-state electrolytes were suggested as the mainstream of electrolytes in the future due to the combination of the advantages of inorganic and polymer quasi-solid-state electrolytes, and their development challenges in high energy and high safety quasi-solid-state lithium metal batteries were also discussed.

Electrochemical reduction of CO2 removed from biosyngas into value-added methanol (CH3OH) provides an attractive way to mitigate climate change, realize CO2 utilization, and improve the overall process efficiency of biomass gasification. However, the economic and environmental feasibilities of this technology are still unclear. In this work, economic and environmental assessments for the stand-alone CO2 electrochemical reduction (CO2R) toward CH3OH with ionic liquid as the electrolyte and the integrated process that combined CO2R with biomass gasification were conducted systematically to identify key economic drivers and provide technological indexes to be competitive. The results demonstrated that costs of investment associated with CO2R and electricity are the main contributors to the total production cost (TPC). Integration of CO2R with CO2 capture/purification and biomass gasification could decrease TPC by 28%-66% under the current and future conditions, highlighting the importance of process integration. Energy and environmental assessment revealed that the energy for CO2R dominated the main energy usage and CO2 emissions, and additionally, the energy structure has a great influence on environmental feasibility. All scenarios could provide climate benefits over the conventional coal-to-CH3OH process if renewable sources are used for electricity generation. Validerad;2023;Nivå 2;2023-02-22 (hanlid)

Combining CO2 electrochemical reduction (CO2R) and biomass gasification for producing methanol (CH3OH) is a promising option to increase the carbon efficiency, reduce total production cost (TPC), and realize the utilization of byproducts of CO2R system, but its viability has not been studied. In this work, systematic techno-economic assessments for the processes that combined CO2R to produce CO/syngas/CH3OH with biomass gasification were conducted and compared to stand-alone biomass gasification and CO2R processes, to identify the benefits and analyze the commercialization potential of different pathways under current and future conditions. The results demonstrated that the process that combined biomass gasification with CO2R to CO represents a viable pathway with a competitive TPC of 0.39 €/kg-CH3OH under the current condition. For all the combined cases, electricity usage for CO2R accounts for 36–76% of total operating cost, which plays a key role for TPC. Sensitivity analysis confirmed that the process that combined biomass gasification with CO2R to CO is sensitive to the price of electricity, while both CO2R performance and prices of stack and electricity are important for the processes that combined with CO2R to syngas/CH3OH. Validerad;2024;Nivå 2;2024-04-15 (hanlid);Full text license: CC BY 4.0

Evaluation for electrochemical CO2reduction to C1 with Ionic liquids.

As ionic liquids (ILs) continue to be prepared, there is a growing need to develop theoretical methods for predicting the properties of ILs, such as gas solubility. In this work, different strategies were employed to obtain the solubility of CO2 and N2, where a conductor-like screening model for real solvents (COSMO-RS) was used as the basis. First, experimental data on the solubility of CO2 and N2 in ILs were collected. Then, the solubility of CO2 and N2 in ILs was predicted using COSMO-RS based on the structures of cations, anions, and gases. To further improve the performance of COSMO-RS, two options were used, i.e., the polynomial expression to correct the COSMO-RS results and the combination of COSMO-RS and machine learning algorithms (eXtreme Gradient Boosting, XGBoost) to develop a hybrid model. The results show that the COSMO-RS with correction can significantly improve the prediction of CO2 solubility, and the corresponding average absolute relative deviation (AARD) is decreased from 43.4% to 11.9%. In contrast, such an option cannot improve that of the N2 dataset. Instead, the results obtained from coupling machine learning algorithms with the COSMO-RS model agree well with the experimental results, with an AARD of 0.94% for the solubility of CO2 and an average absolute deviation (AAD) of 0.15% for the solubility of N2.

Abstract Carbonic anhydrase (CA) has demonstrated great potential to mitigate CO2 emissions by enzymatic conversion of CO2, while its commercial implementation is limited by the inherent shortcomings of CA, such as thermal and chemical instability, high sensitivity to the environment, and high cost. To overcome the drawbacks of CA and develop advanced technologies for mitigating CO2 emission, for the first time, mimetic CA (ZnHisGly) with the characteristics of natural CA was designed and synthesized, i.e., zinc-based deep eutectic solvent (DES), to boost CO2 hydration and conversion. The mimetic CA exhibited facile synthesis, high stability, and low cost as the characteristics of DES, and showed better catalytic performance compared to the currently reported mimetic CA. Particularly, its catalytic performance increased greatly with increasing pH and temperatures, which provides promising prospects in the industrial applications of DES-based CA mimics.