Computational chemistry has played a significant role in catalysis by helping to elucidate the nature of the active site and the reaction mechanism of a wide range of catalysts. Single-atom catalysts (SACs) are an up-coming class of catalytic materials that combine the inherent advantages of homogeneous and heterogeneous catalysts. Ru@MCM-41 is a new heterogeneous catalyst consisting of ruthenium single-atoms incorporated into the walls of MCM-41 and stabilized by a surfactant. Experiments showed that the surfactant has a significant effect on the catalytic activity, and is needed to achieve high turnover-numbers. The unprecedented catalytic activity of Ru@MCM-41 in the hydrogenation of CO2 to formate inspired us to develop an MCM-41 single-atom catalyst model with the aim of understanding the role of all components, leading to the design of a new class of single-atom catalysts. To the best of our knowledge, there is no model reported in the literature that includes the effect of the surfactant. Due to the complexity of MCM-41, an amorphous silica model will be used to perform periodic density functional theory calculations. The results of this project will enable us to understand the structure of the catalyst and its active sites and will provide mechanistic insights into the hydrogenation reactions.