In previous experimental studies, CO2 could be effectively captured by aqueous amine solutions and the resultant carbamate functionalities could be hydrogenated to methanol by using ruthenium (Ru) complexes and H2. This effectively allows the capturing of CO2, minimizing emissions, and its transformation to a product with added value. In our project, we are exploring a new supported homogeneous system in which grafting of an amine-rich polymer on the surface of mesoporous silica will allow the capturing of CO2 while the impregnation of a Ru complex will allow the hydrogenation of the captured CO2 to methanol by using H2 as a hydrogen source. This approach would enable the application of a homogeneous system in a heterogeneous way, with the advantages it entitles such as facile separation of the catalyst and product. The conclusive factors in the supported homogeneous system could be the CO2 capture efficiency, which is related to the type of monomers to graft and the surface density of amine groups on the silica surface. The DFT theoretical calculations by using the Gaussian software could help us screen out some promising amine monomers for experimental tests in the lab and help to understand the CO2 capture mechanisms. Furthermore, the subsequent hydrogenation reactions need to be simulated by DFT calculations for us to improve the methanol production under relatively mild conditions. In addition, the surface structure of the modified mesoporous silica after amine grafting and the Ru complex impregnation could be determined by combining experimental characterizations and theoretical model simulations. Therefore, theoretical calculations are indispensable for this project and your large computing resources are considerable and it would mean a lot to us to be able to use them.
As described above, the theoretical calculation work would include three main sections: 1) the type and loading density of amine groups for CO2 capture, 2) the hydrogenation mechanisms of captured CO2 on modified silica surface, and 3) the structural features of silica surface after amine grafting and Ru complex impregnation. Our targeted Ru complex contains a total of 65 atoms including one ruthenium atom and the representative amine monomers contain 25-36 atoms, therefore, 16 cores are required for each job and at least 10 nodes are necessary for our daily work. For the first and second sections of the work, energy profiles based on targeted changing bands would be scanned to locate transition state structures of the step reactions. For the third section of the work, some theoretical spectral information like IR or Raman, and also NMR chemical shifts would be calculated to support the experimental results. Impact and publications are foreseen, and the designed catalytic system would be a promising alternative for resource usage of CO2 in the methanol economy field.