Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3catalysts to modify the support to enable control over CO2adsorption and CO2hydrogenation activity. Significant differences in catalytic activity toward CO2hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3with PAs, suggesting that the reaction was mediated by CO2adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3support by the PAs.
The synthesis of a range of PBP supported palladium pincer complexes with different alkyl ligands is described. The rates of CO2insertion into the alkyl group are quantified and rationalized based on the identity of the alkyl ligand.
more » « less- Award ID(s):
- 1953708
- PAR ID:
- 10537193
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Chemical Science
- Volume:
- 14
- Issue:
- 30
- ISSN:
- 2041-6520
- Page Range / eLocation ID:
- 8164 to 8179
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D3SC01459B
