Surface Modification of Mg-Al Hydrotalcite Mixed Oxides with Potassium

The surface modification of Mg-Al hydrotalcite mixed oxides (MgAlO) with K was, investigated using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in situ infrared (in situ IR) spectroscopy, and temperature-programmed desorption of CO2 (CO2-TPD) We found that K was highly dispersed on the surface of MgAlO when the loading amount was less than 8% (omega) New Lewis base sites were formed through the interaction between K and MgAlO The weakly basic Mg(Al)-O-K resulted from the proton substitution of Mg(Al)-OH with K Mg-O-K was obtained by combination with strongly basic O2- sites At a K loading between 5% (w) and 8% (w), die quasi free KO, species that interacted weakly with the support and showed stronger basicity than Mg-O-K was formed The increase in basicity of K/MgAlO can be attributed to charge transfer from K to the surface oxygen anions, which increases the negative charge of the strongly basic sites