Tethering of bi-nuclear complexes to SBA-15 and their application in CO2 hydrogenation

Two bimetallic cryptates (containing Cu and Co), which have previously been shown to react with and activate atmospheric CO2, have been tethered to modified mesoporous SiO2 and their activities in promoting the CO2 + H2 reaction has been analysed. The cryptates have been tethered to –C3H6Cl modified SBA-15 through a condensation reaction between surface alkyl chlorides and 2° amines of the ligands releasing HCl and forming a 3° amine. The materials have been characterised using BET, TGA, FTIR and elemental analysis and their activity in promoting the CO2 + H2 reaction has been tested under batch reactor conditions. Co ions appear to selectively populate the medal sites of the tethered ligands while Cu ions appear to deposit on the surface as Cu(BF4)2 salts. The composite materials generate CO and CH4 from the CO2 + H2 mixtures. Co-containing catalysts are more effective than the Cu analogues in promoting the reaction.