Development of New Selective Materials for the Adsorption of Nitrogen Oxides – NOA

Technical obstacles exist ; the proposed process has to be selective: to trap NOx without adsorbing water, and the affinity of the trapping materials with NOx has not to be too high to allow the regeneration. A selection of materials (MOF, zeolites, etc) with properties required will be made thanks to DFT and GCMC calculations. The data analysis will allow their synthesis and their shaping (membranes, monoliths, etc). After a characterization step (isotherm, adsorption enthalpy, breakthrough curve, etc), the adsorption process will be modeled for future development.

The first screening of materials by molecular modeling has allowed us to extract three candidates with high potential. They have been synthesized and are being characterized.

The aim will be to show the viability of these materials for a large-scale application such as on an exhaust line of a thermal engine.

A. Daouli, E. P. Hessou, H. Monnier, M. Dziurla, A. Hasnaoui, G. Maurin and M. Badawi, Adsorption of NO, NO2 and H2O in divalent cation faujasite type zeolites: A Density Functional Theory screening approach. Phys. Chem. Chem. Phys., 2022, DOI: 10.1039/D2CP00553K.

The emission of NOx - nitrogen monoxide (NO) and nitrogen dioxide (NO2) - by engines in a confined work environment without ventilation and exhaust treatments represents major health and safety issues. In France, almost 800,000 workers are exposed to such highly toxic NOx emissions. The NOA project aims to develop a NOx adsorption process for non-road vehicles using an optimal adsorbent. It will be loaded and transportable by the worker, to be placed at the exhaust gas outlet of vehicles. The adsorption cartridge needs then to be periodically changed since it works on an accumulative mode, by gas-solid adsorption. The regeneration of the process will therefore take place in time and deported from the vehicle. The operation chosen is the gas-solid adsorption which is more effective than the catalysis at low temperature. Technical obstacles exist; the proposed process has to be selective: to trap NOx without adsorbing water and carbon dioxide, and the affinity of the trapping materials with NOx has not to be too high to allow the regeneration. Therefore, a selection of materials (MOF, zeolites,) with properties required will be made thanks to DFT and GCMC calculations. The goal is to identify the best adsorbents with the highest affinity and largest uptake to NOx in the presence of H2O and CO2. The most promising adsorbents will be synthesized with different morphologies and characterized. A first principle model based on momentum, heat and mass balances will be developed in order to accurately predict the NOx concentration profiles over time at the outlet of a column containing the best adsorbents. Finally, calculations and experiments will be carried out to sizing and design of a transportable device. A technology transfer to companies for its development will be performed at the end of the project. These different activities are not time-sequential but fully interwoven throughout the development stages and the validation of the innovative concepts. The work program is divided into seven work packages (WP) over the 48 months, each WP comprising from 1 to 5 tasks. Five French teams are involved in this project: four academics and one private association (coordinator). The consortium is complementary; it combines the advantages of a multidisciplinary research, involving chemistry of materials, thermodynamic and kinetic analyses, multiscale modelling (molecular simulations and process simulations), process and chemical engineering applications with efficient synergies. It should identify the most promising adsorbents for a highly challenging targeted selective adsorption, and intends to develop industrial tools for occupational risk prevention and environmental protection. Technology transfer to companies for the development and commercialisation of the optimised material(s) and selected process will be dealt with by the coordinator. The NOA project contains an important part of experimental/modelling investigations. Therefore, it requires the recruitment of scientists as follows: two PhD students, one post-doc (18 months) and one master2 student (6 months). It requires also the purchase of manometry equipment for corrosive gas to carry out adsorption isotherms. The project has no rental costs. It does not request funding for the costs of acquiring licenses, patents, copyrights, etc. A consortium agreement will be established between the five partners in the first year of the project. The financial support requested for NOA project stands at 535 k€ for four years, and at 131 man-months (permanent staff). The scientific impact of the work will appear at various levels, with the three following objectives: (i) sharing research results with the scientific community (conferences, publications, etc) (ii) ensuring a wide awareness of the project to both potential end-users and to the general audience (technology transfer) and (iii) disseminating knowledge to people outside of the consortium through training activities.