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Along the development of ionic porous organic polymers, simple and efficient synthetic methods are actively pursued. Herein, the Debus–Radziszewski reaction is applied to synthesize ionic conjugated microporous polymers (iCMPs) in one step. A series of imidazolium‐linked iCMP‐X (X = 1, 2, 3) are developed for CO2 sorption and in situ conversion with epoxide into cyclic carbonates. The as‐synthesized iCMPs are characterized in detail by scanning electron microscope, solid‐state nuclear magnetic resonance, X‐ray photoelectron spectroscopy, X‐ray diffraction analysis, N2/CO2 sorption, and more. Among all synthesized iCMPs, iCMP‐1 possesses the highest specific surface area and in turn the strongest CO2 sorption capacity. Moreover, through a simple anion ion exchange reaction with halide, iCMP‐1 is transformed to iCMP‐1@Cl that embodies significant catalytic capability for converting CO2 into cyclic carbonates. [ABSTRACT FROM AUTHOR]

• The Widom lines of four thermodynamic properties of CO2/natural gas mixtures were calculated to study the characteristics of supercritical mixtures at near critical points. • A new Widom line vanishing point criterion based on the coefficient of variation was proposed with a moderate range, clear statistical significance, and a better economy for industrial applications. • Results show that the influence of CO2 concentration on the characteristic of "thermodynamic fluctuations" of the mixture does not increase uniformly, but is positively correlated with concentration. It can be considered that mixtures with xCO 2 = 0 ∼ 0.6 exhibit weak fluctuations. • Results show that different equipment need to avoid different Widom lines and maintain a safe temperature margin about 20 ∼ 30 K. The Widom lines of mixture indicate the abnormal response behavior of properties of mixed supercritical fluid near the critical point, determining operating conditions in supercritical region of ground equipment in CCUS. Peng-Robinson equation (PR-EOS) is used to calculate Widom lines of isothermal compressibility coefficient, isobaric expansion coefficient, isobaric specific heat, and density of CO 2 /natural gas quinary mixture. A new criterion is proposed to calculate the vanishing points of Widom lines using the coefficient of variation (CV) of response function distribution, with a clear statistical meaning and an appropriate range, compared with existing criteria. Based on the new criterion, the effect of CO 2 concentration on the thermodynamic fluctuations in the near-critical region of CO 2 /natural gas mixture is analyzed. It is found that thermodynamic fluctuations of mixture are controlled by CO 2 concentration and fluctuations can be considered relatively weak when CO 2 concentration is below 60 %. The selection and control of operating conditions of pipeline and compressor unit in CCUS application are discussed to cope with the Widom region movement caused by changes in CO 2 concentration. [ABSTRACT FROM AUTHOR]

The excellent catalytic activity of [N 2,2,2,2OH ][SA] is traced to the critical role played by nucleophilic-electrophilic dual activation from [SA]- anions in the cycloaddition reaction of CO 2. [Display omitted] • The catalytic mechanism of carboxylate anion-based ionic liquids is firstly elucidated in this work. • The catalytic role of carboxylate anions is complex and flexible. • The underlying electrophilic activation ability of the carboxylic acid anion plays a critical role in enhancing the catalytic activity. • The electrophilic activation plays a more important role than nucleophilic activation in the ring-opening step. Elucidating the mechanism of carbon dioxide (CO 2) cycloaddition reaction catalyzed by ionic liquid (ILs) facilitates the rational design of efficient IL catalysts at the molecular level. To date, a great deal of research has been devoted to the halogen-containing ILs, however, the catalytic mechanism of halogen-free ILs remains unclear. In this contribution, an exhaustive theoretical study of the coupling reaction of CO 2 with epichlorohydrin (ECH) catalyzed by three halogen-free ILs has been carried out for the first time by combining density functional theory (DFT) calculations with molecular dynamics (MD) simulations. Meanwhile, the effect of carboxylate anion structure on catalytic activity is deeply investigated. The final results provide a comprehensive catalytic mechanism of carboxylate anion-based ILs. The most favorable mechanism involves three steps, i.e., ring-opening of ECH, CO 2 insertion, and ring-closure to form the product. Among them, the ring-opening of ECH is the rate-determining step (RDS). Additionally, the analytical results of the independent gradient model based on Hirshfeld partition (IGMH) and atoms in molecules (AIM) suggest that the electrophilic activation from carboxylate anions plays a critical role in promoting the ECH ring-opening process. The electrophilic activation of anions is investigated for the first time in this work. The results indicate that incorporating electrophilic groups into anions is a promising pathway to develop new robust and efficient halogen-free ILs. [ABSTRACT FROM AUTHOR]