SBA-15-supported highly dispersed copper catalysts: Vacuum–thermal preparation and catalytic studies in propylene partial oxidation to acrolein

• The catalysts with highly dispersed Cu species on SBA-15 have been prepared.
• Vacuum–thermal treatment is the critical step for forming small Cu particles.
• They exhibit high activity in propylene partial oxidation to acrolein with O2.
• Small-sized Cu and hydrophobic mesopore surface are beneficial to the reaction.
• Only Cu(I) and Cu(II) species are present under reaction conditions.

SBA-15-supported copper catalysts containing highly dispersed Cu2O particles with Cu/Si of up to 20% were successfully prepared by simple impregnation followed by vacuum–thermal treatment. The Cu2O particles were reduced by hydrogen, and the resulting catalysts with small (1–4 nm) metallic Cu particles were applied for partial oxidation of propylene with molecular oxygen. The catalysts exhibited high activity and high acrolein selectivity. The presence of trimethylsilyl groups on the mesopores of SBA-15 was found advantageous for higher propylene conversion and acrolein yield and better catalytic stability. The relationship between conversion and selectivity was also studied. The best catalyst, with Cu/Si = 10%, showed an acrolein yield of 12.3% at 300 °C. In situ X-ray absorption spectroscopic study indicated that only Cu(I) and Cu(II) species are present under reaction conditions, with the fraction of Cu(II) increasing with rising temperature.

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