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Title: Using Phosphonic Acid Monolayers to Control CO 2 Adsorption and Hydrogenation on Pt/Al 2 O 3
Abstract 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.  more » « less
Award ID(s):
2004090
PAR ID:
10529927
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
ChemCatChem
ISSN:
1867-3880
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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