Structural changes in a bi-functional dimethyl ether synthesis catalyst (CuO-ZnO-Al2O3-MgO + gamma-Al2O3, BFC), a methanol synthesis catalyst (CuO-ZnO-Al2O3-MgO, MSC) and a methanol dehydration catalyst (gamma-Al2O3, MDC), were studied using X-ray synchrotron powder diffraction. The catalysts were first reduced in 10% H-2/He and then treated in a gas containing CO, H-2 and CO2. Measurements were taken at temperatures between 50 degrees C and 500 degrees C. These measurements were complemented by ex-situ techniques-thermogravimetry (TG) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction (XRD) results showed that the copper oxide phase, present in methanol synthesis and bi-functional catalysts, reduced to form Cu-0 after reduction. No further chemical changes were observed for these catalysts. gamma-Al2O3 was resistant to structural and chemical changes. The copper crystallite sizes of the methanol and bi-functional catalysts were found to increase with temperature. The extent of deactivation was higher for CuO-ZnO-Al2O3-MgO + gamma-Al2O3 compared to CuO-ZnO-Al2O3-MgO. (C) 2014 Elsevier B.V. All rights reserved.