Adsorption and reactions of CH3Cl on Mo2C based catalyst

First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Zeolite chemistry and catalysis are expected to play a decisive role in the next decade(s) to build a more decentralized renewable feedstock-dependent sustainable society owing to the increased scrutiny over carbon emissions. Therefore, the lack of fundamental and mechanistic understanding of these processes is a critical "technical bottleneck" that must be eliminated to maximize economic value and minimize waste. We have identified, considering this objective, that the chemistry related to the first-generation reaction intermediates (i.e., carbocations, radicals, carbenes, ketenes, and carbanions) in zeolite chemistry and catalysis is highly underdeveloped or undervalued compared to other catalysis streams (e.g., homogeneous catalysis). This limitation can often be attributed to the technological restrictions to detect such "short-lived and highly reactive" intermediates at the interface (gas-solid/solid-liquid); however, the recent rise of sophisticated spectroscopic/analytical techniques (including under in situ/operando conditions) and modern data analysis methods collectively compete to unravel the impact of these organic intermediates. This comprehensive review summarizes the state-of-the-art first-generation organic reaction intermediates in zeolite chemistry and catalysis and evaluates their existing challenges and future prospects, to contribute significantly to the "circular carbon economy" initiatives.

Interaction process between gaseous CH3I and NaCl particles: implication for iodine dispersion in the atmosphere

Gaseous iodomethane (CH₃I) is naturally emitted into the atmosphere by biological activity in oceans and during severe accidents (SAs) in nuclear power plants. In this latter case, a part of radioactive iodine such as ¹³¹I may be released. Improving the knowledge of CH₃I transport and reactivity in the atmosphere is important since they are strongly linked to first the cycle of ozone and second to the dispersion of radioactive CH₃I with potential radiological consequences on both the environment and human health. Here, the interaction process of CH₃I with NaCl as a surrogate of atmospheric aerosols was investigated under ambient air conditions by using Diffuse Reflectance Fourier Transform Spectroscopy (DRIFTS). The DRIFTS spectra of NaCl clearly evidenced CH₃I adsorption on the NaCl particle surface. A part of CH₃I ((1.68 ± 0.85) × 10¹⁴ molecule per mg_NaCl) was found to be strongly bonded to NaCl since no desorption was observed. The CH₃I adsorption on the NaCl surface presented a 1^st order kinetics relative to its gas phase concentration. The uptake coefficient was determined to be in the order of 10^-11. These results show a low probability of CH₃I to be taken up by halide-containing aerosols. These data are crucial for completing the iodine atmospheric chemical scheme.