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Nitrogen oxides, present in flue gas, can cause negative impacts on amine carbon capture solvents by the formation of heat-stable salts and suspected carcinogens. Thus, to maximize the performance of water-lean solvents, a better understanding of this process in these systems is necessary. Here, a computational study for the fixation of the CO2capture solvent N-(2-ethoxyethyl)-3-morpholinopropan-1-amine (EEMPA) to nitramine/nitrosamine was conducted. The first step involves the dissociation of the NH bond of EEMPA, in which the homolytic mechanism is energetically more favorable than the heterolytic mechanism. The second step involves radical recombination to form N–N bonds. While NO2directly reacts with EEMPA, NO has almost no effect. However, in the presence of O2, fixation of EEMPA by NO is enhanced via the formation of N2O4species. Low reaction energies indicate that the formation of nitramine/nitrosamine may be a reversible process, suggesting that EEMPA could be recovered under thermal stripping conditions.

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.

An integrated CO2capture and conversion to materials (IC3M) implementation utilizing a CO2capture solvent is an efficient approach to reduce the amount of CO2in the atmosphere while producing value-added chemicals. Herein, we demonstrate that the advanced water-lean CO2capture solvent, N-(2-Ethoxyethyl)-3-morpholinopropan-1-amine (EEMPA), can catalyze the cycloaddition reaction between CO2and propylene oxide to produce the value-added chemical propylene carbonate in an IC3M fashion. When excess propylene oxide is used relative to EEMPA, yields as high as 75% with 85% selectivity toward propylene carbonate can be achieved under solvent-free conditions without the need of additives/cocatalysts. The reaction temperature (120 °C) is comparable to that used in the thermal regeneration of the capture solvent under industrial conditions. Formation of an undesired amino alcohol side product was observed, but it may be reversible or avoidable with continued research despite the unsuccessful initial attempts. Lastly, we show that this can be applied to other epoxides for the production of various cyclic carbonates.

The gas processing unit (GPU) has previously been identified as the least thermodynamically efficient element of an oxycombustion process. A marginal improvement of this unit operation can provide a greater decrease of the parasitic power to the oxycombustion process than an equivalent improvement in the air separation unit (ASU). Hence, capturing CO2from oxycombustion using an alternative method than the conventional cryogenic process has potential to reduce the parasitic power consumption of the GPU. In this work, the authors present an initial evaluation of a new process concept; a hybrid oxycombustion process that uses a solvent-based GPU to capture CO2from the flue gas. N-Ethyldiethanolamine (EDEA) is a tertiary alkanolamine that captures CO2by forming a zwitterionic ammonium alkylcarbonate ionic liquid in the absence of water as a cosolvent. The new solvent-based GPU proposed herein demonstrates a clear potential to improve the net power efficiency by 1%, a 9% CAPEX reduction, and up to 5% LCOE reduction of an oxycombustion process if the price of EDEA is below $270/kg. Both lower CAPEX and the potential of reduced LCOE demonstrates that alternative CO2capture methods for oxycombustion can be more economical.

Increasing numbers of standards for emissions and fuel economy drive the need to downsize spark ignition internal combustion engines. To accommodate this change while reducing engine knock, fuels with higher octane numbers are needed. However, studies have shown that octane requirements are not uniform across the vehicle drive cycle, leading to inefficient use of the high-octane fuel components. One approach shown to substantially increase fuel economy through the efficient use of high-octane fuel components is a dual-fuel solution called octane-on-demand. Octane-on-demand supplies fuel that has the required octane rating, as dictated by the engine torque demands, by delivering the proper ratio of high- and low-octane fuels. Barriers associated with introducing two fuels in the marketplace for an octane-on-demand approach can be overcome using an onboard separation system to separate a single fuel, such as a market E10 gasoline, into a high-octane oxygenate, such as ethanol, and a lower-octane base fuel. Onboard separation systems currently under evaluation rely on pervaporation membranes, which lose efficiency as the oxygenate is removed, leading to inefficient use of this valuable fuel component. Here, we present liquid–solid and liquid–liquid chemical separation strategies that may provide advantages over membrane separation. This paper introduces applications of tailored chemical reactions, solid sorbent materials, and ionic liquids that are shown to have a high oxygenate recovery and utility beyond ethanol to potential future oxygenate additives, such as isomers of butanol.

A low-temperature CH3OH synthesis was achieved at 120–170 °C using tertiary amine and alcohol in the presence of a Cu/ZnO/Al2O3catalyst by CO2hydrogenation. A series of 1°, 2° and 3° amines and alcohols were screened to study their influence on the formation of CH3OH. Particularly, 3° amines such as NEt3in combination with EtOH formed CH3OH with 100% yield with respect to the amine. Unlike the traditional gas-phase heterogeneous metal catalyzed CO2-to-CH3OH reactions, no CO is used in the feed gas mixture in this method. In addition, the hydrogenation gives good selectivity (>95%) to CH3OH and only trace amounts of CO and CH4are formed. The presence of CO in the gas mixture was attributed to the decomposition of the CH3OH product, which was confirmed by high-temperature and high-pressure MAS NMR. The reaction was performed in the condensed phase at relatively lower temperatures, thus the RWGS reaction, which typically operates at >250 °C, was significantly reduced at these temperatures (120–170 °C). The first in situspectroscopic evidence for the condensed phase hydrogenation of alkylcarbonate to CH3OH viaammonium formate and alkylformate intermediates was also presented under the experimental conditions.

Three water adsorption–desorption mechanisms are common in inorganic materials: chemisorption, which can lead to the modification of the first coordination sphere; simple adsorption, which is reversible; and condensation, which is irreversible. Regardless of the sorption mechanism, all known materials exhibit an isotherm in which the quantity of water adsorbed increases with an increase in relative humidity. Here, we show that carbon-based rods can adsorb water at low humidity and spontaneously expel about half of the adsorbed water when the relative humidity exceeds a 50–80% threshold. The water expulsion is reversible, and is attributed to the interfacial forces between the confined rod surfaces. At wide rod spacings, a monolayer of water can form on the surface of the carbon-based rods, which subsequently leads to condensation in the confined space between adjacent rods. As the relative humidity increases, adjacent rods (confining surfaces) in the bundles are drawn closer together via capillary forces. At high relative humidity, and once the size of the confining surfaces has decreased to a critical length, a surface-induced evaporation phenomenon known as solvent cavitation occurs and water that had condensed inside the confined area is released as a vapour.

Under anoxic conditions, a novel nanoparticulate green rust with carbonate (nano GR) was synthesised by the addition of methanol to degassed switchable ionic liquid (SWIL) solution composed of 1-hexanol, diazabicycloundec- 7-ene (DBU), CO2and Fe(C2H3O2)2. Variable temperature Mössbauer spectroscopy studies indicated the product to be predominantly GR while transmission electron microscopy selected area diffraction confirmed it was nanoparticulate in nature. Experiments with and without methanol in the SWIL medium suggest that methanol may be responsible for the Fe(II) oxidation to Fe(III) necessary for GR formation. Studies with Ar instead of CO2 trigger gas indicated that CO2is essential for GR formation. Conditions to generate CO32- anions were most likely provided by the basic environment of the medium. The nano GR suspension was very reactive and instantaneously oxidised completely to a reddish brown precipitate upon exposure to ambient atmosphere. The nature of the oxidised product is not certain. The oxidised product, however, appears to be a mix of ferric green rust [GR(CO32-*); major] and ferrihydrite- like mineral. To our knowledge, this is the first a) example of synthetic nanoparticulate GR, and b) report of use of environmentally friendly SWIL reagents to synthesise GR materials.

Carbon capture represents a key pathway to meeting climate change mitigation goals. Powerful next-generation solvent-based capture processes are under development by many researchers, but optimization and testing would be significantly aided by integrating in situ monitoring capability. Further, real-time water analysis in water-lean solvents offers the potential to maintain their water balance in operation. To explore data acquisition techniques in depth for this purpose, Raman spectra of CO2,H2O, and a single-component water-lean solvent, N-(2-ethoxyethyl)-3-morpholinopropan-1-amine (2-EEMPA) were collected at different CO2and H2O concentrations using an in situ Raman cell. The quantification of CO2and H2O loadings in 2-EEMPA was done by principal component regression and partial least squares methods with analysis of uncertainties. We conclude with discussions on how this simultaneous online analysis method to quantify CO2and H2O loadings can be an important tool to enable the optimal efficiency of water-lean CO2solvents while also maintaining the critical water balance under operating conditions relevant to post-combustion CO2capture.

CO2‐binding organic liquids (CO2BOLs) are mixtures of a base (typically an amidine or guanidine) and an alcohol, and have been shown to reversibly capture and release CO2with low reaction energies and high gravimetric CO2capacity. We now report the ability of such liquid blends to chemically bind and release other acid gases such as CS2, COS, and SO2analogously to CO2. These systems bind with sulfur‐containing acid gases to form colored ionic liquids with new O‐alkylxanthate, O‐alkylthiocarbonyl, and O‐alkylsulfite anions. The capture and thermal stripping of each acid gas from these systems and their applicability towards flue gas desulfurization is discussed.

Looking to the future: The decomposition in solution of a potential hydrogen‐storage compound, ammonia borane (AB), was investigated by in situ 11B NMR spectroscopy and ex situ 15N NMR spectroscopy. The reaction was found to be second order in AB with an activation barrier of (25±2) kcal mol−1. The second‐order kinetics have implications for the use of solutions containing AB in high concentrations for hydrogen storage.

Nonvolatile solvents eliminate the health and environmental risks associated with volatile solvent use, but may pose their own risks and separation problems. Several liquid polymers are compared in terms of environmental risk, solvent polarity, and performance as solvents for homogeneously-catalyzed and whole-cell-catalyzed reductions. Asymmetric catalyst use and recycling was demonstrated using a combination of liquid polymer and supercritical CO2. A polymeric solvent was also found to protect air-sensitive catalysts from inactivation due to exposure to air.

•The membrane-solvents hybrid system provides benefits to CO2capture•ToF-SIMS and XPS analyses of the CO2separation membrane and capture solvents•Surface analysis shows interactions between the membrane and capture solvents•Improved compatibility needed for molecular structure design and direct air capture

[(NH3)2BH2]+[BH4]‐is obtained by room temperature solid state decomposition of an equimolar mixture of NH4BH4and NH3BH3(milling, 10 min) and its crystal structure is determined by Rietveld refinement of combined X‐ray and neutron powder diffraction data.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.