## 2 Materials and Methods
### Preparation of Materials  
From the project \"Combustion with CO2 capture using solid oxygen carriers (Chemical Looping Combustion)\" to find potential low-cost SOCs in the country, 16 natural minerals of different types were characterized by X-ray fluorescence (XRF) analysis. In their regions of origin, these materials are mining designer minerals. Among them is the manganese-based mineral called OXMN009 in the present study. To improve this material, it is first impregnated with copper, obtaining a manganese-based mineral enhanced with copper called 0 XMN009P. Data, such as a breaking strength of 5.7, were also obtained. These two minerals are solid oxygen carriers tested on a thermogravimetric balance (TGA) using CH4, CO, and H2 as the fuel. To achieve the particle size required to perform the tests on the thermogravimetric balance, a mill with a blade accessory was used, and the ground sample was passed through a No. 70 sieve (Tyler series), which guaranteed a diameter between 100 and 300 \(\upmu\)m.  
The screening and sufficiency process of the size of the manganese-based oxygen transporter was carried out. Calcination was performed on the 0 XMN009 solid conveyor to increase its mechanical strength and obtain a modified manganese 0 XMN009P using the incipient impregnation method for Cu processing of the selected sample, adding a 5 M solution volume of copper nitrate trihydrate (Cu(NO3)2\(\cdot\)3H2O) corresponding to the pore volume of the material, which allowed contact between the ore and the impregnant. The copper nitrate was decomposed into copper oxide, the sample was calcined at a temperature of 550 \({}^{\circ}\)C, and finally, a second calcination was performed at 850 \({}^{\circ}\)C to stabilize the sample.  
The available materials (original and modified solid oxygen carriers) were characterized by X-ray fluorescence (XRF) to quantify the concentration of manganese-basedmaterials, followed by thermogravimetric analysis. Scanning electron microscopy (SEM) characterization and X-ray diffraction (XRD) were performed to identify the crystalline phases in oxygen-carrying particles.  
For TSO's XRF analysis, a PANalytical AXIOS max sequential wavelength dispersive X-ray fluorescence spectrometer (WDXRF) was equipped with a rhodium tube with a maximum power of 4.0 KW. It used a primary hybrid monochromator that produces a parallel beam, ideal for studying grazing samples (thin layers) to quantify elements present in the sample and help read the diffraction pattern information obtained with XRD.  
For the XRD analysis of the TSOs, Panalytical Empyrean equipment with a cobalt X-ray source was used to perform a sweep between the 20\({}^{\circ}\) and 100\({}^{\circ}\) angles of the 200 range to identify the crystalline phases of the materials.  
The SEM analysis was performed using a JEOL-JSM 6490 LV Scanning Electron Microscope (JEOL Ltd., Tokyo, Japan). This microscope uses electrons instead of light to form the image. To achieve this, the device has a filament that generates a beam of electrons to illuminate the sample. If the sample is not conductive, it must be covered with a thin layer of gold. The images produced by this method can be used to determine the morphology of SOC.  
EDS analysis was used for elemental identification by chemical mapping using the same electron microscopy described above, which helped identify the Cu deposited in the immersion-treated SOC.