The use of anthropogenic CO 2 as a carbon source for the synthesis of value-added chemicals, mainly light olefins, is a green route that has not been extensively explored. Designing robust catalysts for the production of olefins is a challenge due to the current lack of clarity on the complex CO 2 hydrogenation mechanism. This review aims to elucidate the production of olefins from CO 2 with an emphasis on material design and existing mechanistic evidence. The major focus is on catalyst design and structure−activity relationships that can mold future progress in this area with significant relevance to industrial implementation. The mechanisms used in these catalytic routes are discussed at length with appropriate examples. Furthermore, practical reactor design, efficient process engineering, and the importance of life cycle analysis are discussed in depth. These are relevant parameters that need to be integrated with catalyst design to overcome scientific and technological challenges to reach the commercial viability of this technology.
A new chemodosimetric protocol based on a tandem S-alkylation followed by desulfurisation reaction of rhodamine-thioamide with mustard gas is reported. The chemodosimeter is highly selective for potential DNA alkylating agents like sulfur mustard, over other simple alkyl halides with the limit of detection of 4.75 μM.
Extraction and identification of lethal nerve agents and their markers in complex organic background have a prime importance from the forensic and verification viewpoint of the Chemical Weapons Convention (CWC). Liquid-liquid extraction with acetonitrile and commercially available solid phase silica cartridges are extensively used for this purpose. Silica cartridges exhibit limited applicability for relatively polar analytes, and acetonitrile extraction shows limited efficacy toward relatively nonpolar analytes. The present study describes the synthesis of polymeric sorbents with tunable surface polarity, their application as a solid-phase extraction (SPE) material against nerve agents and their polar as well as nonpolar markers from nonpolar organic matrices. In comparison with the acetonitrile extraction and commercial silica cartridges, the new sorbent showed better extraction efficiency toward analytes of varying polarity. The extraction parameters were optimized for the proposed method, which included ethyl acetate as an extraction solvent and n-hexane as a washing solvent. Under optimized conditions, method linearity ranged from 0.10 to 10 μg mL ( r = 0.9327-0.9988) for organophosphorus esters and 0.05-20 μg mL ( r = 0.9976-0.9991) for nerve agents. Limits of detection (S:N = 3:1) in the SIM mode were found in the range of 0.03-0.075 μg mL for organophosphorus esters and 0.015-0.025 μg mL for nerve agents. Limits of quantification (S:N = 10:1) were found in the range of 0.100-0.25 μg mL for organophosphorus esters and 0.05-0.100 μg mL for nerve agents in the SIM mode. The recoveries of the nerve agents and their markers ranged from 90.0 to 98.0% and 75.0 to 95.0% respectively. The repeatability and reproducibility (with relative standard deviations (RSDs) %) for organophosphorus esters were found in the range of 1.35-8.61% and 2.30-9.25% respectively. For nerve agents, the repeatability range from 1.00 to 7.75% and reproducibility were found in the range of 2.17-6.90%.
Extraction of vesicant class of chemical warfare agents (CWAs) such as sulfur mustard and nitrogen mustards from the environmental matrices is of prime importance, from a forensic and verification viewpoint of the Chemical Weapons Convention (CWC). For extraction of Convention Related Compounds from nonpolar organic medium, commercially available silica cartridges are used extensively, but silica cartridges exhibit limited efficiency toward vesicant classes of compounds. It is expected that sulfur mustard being nonpolar does not retain sufficiently on silica surface, and nitrogen mustards (being basic) are strongly adsorbed on acidic silica surface, resulting in their poor recoveries. Contrary to the expected higher recovery of sulfur mustard over nitrogen mustards, it was observed that the recovery of sulfur mustard was lower than that of nitrogen mustards with the silica based sorbent. The reason for this typical behavior of these agents on silica was investigated. This study was aimed to develop an analytical method for efficient extraction and enrichment of sulfur and nitrogen mustards from hydrophobic matrices. In this work, the polymeric sorbent was synthesized with polar methacrylic acid (MAA) as monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker and used for solid phase extraction (SPE) of sulfur mustard and nitrogen mustards. The extraction efficiency of the polymeric sorbent was optimized and compared with that of silica cartridges. Both classes of analytes were recovered in good amounts from the polymeric sorbent compared to silica. The extraction parameters were optimized for the proposed method which included extraction solvent ethyl acetate and washing solvent n-hexane (1 mL). The recoveries of the analytes ranged from 75 to 87% with relative standard deviations (RSDs) lower than 9%. The limit of detection (LOD) was found to be in the range of 0.075-0.150 μg mL, and limit of quantification (LOQ) was >0.25 μg mL. The linear dynamic range of optimized method was found to be 0.50-20 μg mL ( r = 0.9994) for sulfur mustard and 0.25-20 μg mL ( r = 0.9897-0.9987) for nitrogen mustards, respectively.
Conversion of CO2 to higher alcohols (HAs)
and higher
hydrocarbons (HCs) has a greater advantage compared to C1 products
because of their high energy density and wide range of applications
in daily life. Despite the immense potential of these chemicals, not
much of scientific research has been focused on the conversion of
CO2 to HAs. In the present work, we have introduced the
concept of strain in designing the material to enhance the CO2 to HA performance. We introduced strain in a traditional
iron-based catalyst, Fe2O3, by the introduction
of indium (In), which facilitates the selective conversion of CO2 to HA. An optimum strain favored a 36.7% CO2 conversion
with a 42% HA selectivity, and a record yield of 15.42%. The strain
has been tuned further with the introduction of K as a promoter. The
introduced strain upon In substitution and K promotion favored the
conversion of CO2, which is mapped by powder X-ray diffraction,
X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy.
Further, the change in the mechanism upon In incorporation and K promotion
has been probed by in situ diffuse reflectance infrared fourier transform
spectroscopy, and it is found that the OCH
x
intermediate, which produces HAs, is more prominent upon In substitution,
which favored the enhancement of HA production compared to that of
pristine Fe2O3.
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