In situ cell for combined XRD and on-line catalysis tests: Studies of Cu-based water gas shift and methanol catalysts

A newly developed in situ X-ray diffraction (XRD) cell has been used to obtain information on the structure of binary CuZn and ternary CuZnAl catalysts during reduction and water gas shift and methanol synthesis. A major advantage of the cell is that it also serves as an ideal plug flow catalytic reactor such that realistic catalytic and structural information can be obtained simultaneously on the same sample. The cell can be operated both at high temperatures and high pressures. Direct methanol activity tests confirmed the suitability of the cell. By use of X rays from a synchrotron source, dynamic studies on the time scale of seconds have been demonstrated. This feature was used to study the phase transformation occurring during the activation of the calcined catalysts. In the active catalysts, Cu metal is the only crystalline Cu phase observed, and the formation of this phase is seen to be closely related to the disappearance of CuO in the calcined catalyst. The XRD results provide detailed information on the nucleation and growth processes. The variation in the water gas shift activity appears to correlate with the changes in the copper surface area.