Can surface energy measurements predict the impact of catalyst hydrophobicity upon fatty acid esterification over sulfonic acid functionalised periodic mesoporous organosilicas?

Hydrothermal Saline Promoted Grafting of Periodic Mesoporous Organic Sulfonic Acid Silicas for Sustainable FAME Production

“…The sulfonic acid loadings achievable through HSPG shown in Table 1 were significantly higher than those previously reported through toluene grafting, wherein loadings of only 0.03 and 0.2 mmol.g -1 were achieved for PrSO3H/SBA-BTSB(50) and PrSO3H/SBA respectively [17]. It is interesting to note that the sulfonic acid loading and concomitant acid site density can also be systematically tuned by varying the framework organic content during PMO synthesis (Fig.…”

“…We should note that palmitic acid conversions over these sulfonic acid SBA-BTSB catalysts (including the SBA-BTSB0%, i.e. SBA-15 analogue) prepared via the HSPG method were at least five times higher than the best achievable via toluene grafting of sulfonic acid functions [17]. The stability of grafted sulfonic acid groups was also evaluated by assessing catalyst recyclability following propanoic acid esterification (Fig S20), which shows that activity is unchanged upon reuse with an initial rate of 3 mmolh -1 maintained.…”

“…The hydrophobic nature of such PMOs is claimed to promote water removal from the active acid sites, and indeed dispersive surface energies (a quantitative measure of hydrophobicity) determined by Inverse GC proved an accurate predictor of palmitic acid esterification activity [17]. However, the low acid site loading and resultant poor conversions have hampered the practical application of these acid functionalised PMOs.…”

“…Sulfonic acid functionalised PMO materials have been explored for a range of reactions spanning condensation [15], etherification [16] and esterification [17]. The hydrophobic nature of such PMOs is claimed to promote water removal from the active acid sites, and indeed dispersive surface energies (a quantitative measure of hydrophobicity) determined by Inverse GC proved an accurate predictor of palmitic acid esterification activity [17].…”

Impact of Hydrophobic Organohybrid Silicas on the Stability of Ni2P Catalyst Phase in the Hydrodeoxygenation of Biophenols

“…From this equation, can be obtained from the slope of a plot of against . The specific interactions can be determined by calculating the difference of for a polar probe molecule, for example, methanol, dichloromethane, and ethyl acetate to the plot of against for the series of homologous of n ‐alkanes …”