Synthesis and characterisation of mesoporous silica phases containing heteroatoms, and their cation exchange properties. Part 2. Cation exchange isotherms for MCM-41 phases

Well characterised MCM phases containing aluminium and zinc heteroatoms were selected from those described in Part 1 [A. Dyer, J. Newton, M. Pillinger, Micropor. Mesopor. Mater. (2009), doi:10.1016/j.micromeso.2009.06.002] to this series. Cation exchange isotherms were constructed for the replacement of Na cations from the solid phases by Li, K, Rb, Cs, NH4, Mg, Ca, Sr, Ba, and Al cations. Thermodynamic assessment of the isotherms enabled selectivity series to be drawn up. Comparisons have been drawn to similar results measured for high-silica zeolites. These included standard free energy values.