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Keywords:

  • carbon dioxide fixation;
  • cobalt;
  • copper;
  • cryptands;
  • hydrogenation

Abstract

Two bimetallic cryptates (containing Cu and Co), which have previously been shown to react with and activate atmospheric CO2, were tethered to modified mesoporous SiO2 and their activities in promoting the CO2+H2 reaction has been analysed. The cryptates were tethered to [BOND]C3H6Cl-modified SBA-15 through a condensation reaction between surface alkyl chlorides and 2° amines of the ligands, which released HCl and formed 3° amine linkages. The materials were characterised using BET, thermogravimetric analysis, FTIR and elemental analysis and their activities in promoting the CO2+H2 reaction was tested under batch reactor conditions. Co ions appear to selectively populate the medal sites of the tethered ligands whereas 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 their Cu analogues in promoting the reaction.