13C NMR study of the influence of the Aerosil surface charge on the short-chain surfactant adsorption

Popova, M. V.; Tchernyshev, Y. S.; Michel, D.

doi:10.1007/s00396-006-1565-9

Cited by 6 publications

(4 citation statements)

References 27 publications

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“…Additionally, concerning the coupling constant effect, proton decoupled 13 C NMR does not suffer from spin coupling due to the very low natural abundance of 13 C (1.1%). 13 C NMR has been used to investigate oligomers grafted onto silica surfaces [ 16 ], ionic surfactants adsorbed on silica [ 17 ], and within catalysis, for example to study the adsorption of hydrocarbons on zeolites [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

et al. 2022

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The different activity of a 1% Pd/carbon catalyst towards aromatic and aliphatic aldehydes hydrogenation has been explored by 13C NMR relaxation. The ratio between T1 relaxation times of adsorbed (ads) and free diffusing (bulk) molecules (T1ads/T1bulk) can be used as an indicator of the relative strength of interaction between the reactant and the catalytic surface, where the lower the T1ads/T1bulk, the higher the adsorption strength. It can be seen that 1% Pd/carbon showed a reverse catalytic behaviour towards benzaldehyde and octanal hydrogenation, which can be explained by analysing the T1 relaxation times related to each substrate in the presence of the catalyst. Comparing and correlating the different T1ads/T1bulk values, we were able to prove that the different catalytic results mainly depend on the contrasting adsorption behaviour of substrates on the catalyst. Moreover, the role of the solvent has been disclosed, as NMR results revealed that the adsorption of the reactants was strongly affected by the choice of solvent, which is revealed to be critical in modulating catalytic activity. As a consequence, T1ads/T1bulk measurements can provide a guide to the selection of appropriate reaction conditions for improving catalytic activity.

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Section: Introductionmentioning

confidence: 99%

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

et al. 2022

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“…A larger chemical shift change Dd indicates stronger adsorption. 5 This interpretation can be complicated by external factors such as the change of polarisation within an adsorbed molecule 6 and the variation with surface coverage. 7 Nevertheless, this method has been used to study the chemisorption of hydrogen on Pt and Pd surfaces using 1 H NMR, 7 and of fluorine-containing adsorbates on a variety of surfaces, including aluminas, using 19 F NMR.…”

Section: Introductionmentioning

confidence: 99%

“…7 Nevertheless, this method has been used to study the chemisorption of hydrogen on Pt and Pd surfaces using 1 H NMR, 7 and of fluorine-containing adsorbates on a variety of surfaces, including aluminas, using 19 F NMR. 8 13 C NMR has been used to investigate oligomers grafted onto silica surfaces, 9 ionic surfactants adsorbed on silica, 5 and in applications to catalysis; for example, hydrocarbon adsorption on zeolites. 6 The use of 13 C NMR has practical advantages over 1 H NMR.…”

Section: Introductionmentioning

confidence: 99%

“…Elsewhere, Popova and co-workers have employed 13 C NMR in order to investigate the variation in T 1 along the carbon-chain of a surfactant inside porous SiO 2 . 5 In this case the pore space was filled with liquid surfactant and hence the adsorbate-adsorbent interaction was not probed directly; it was modified by molecular exchange with bulk liquid in the pore. As neither of these studies considered the ratio of the measured relaxation time against that of the bulk liquid, only general trends could be established.…”

Section: Introductionmentioning

confidence: 99%

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Determining adsorbate configuration on alumina surfaces with ¹³C nuclear magnetic resonance relaxation time analysis

Vecino

Huang

Mitchell

et al. 2015

Phys. Chem. Chem. Phys.

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Relative strengths of surface interaction for individual carbon atoms in acyclic and cyclic hydrocarbons adsorbed on alumina surfaces are determined using chemically resolved (13)C nuclear magnetic resonance (NMR) T1 relaxation times. The ratio of relaxation times for the adsorbed atoms T1,ads to the bulk liquid relaxation time T1,bulk provides an indication of the mobility of the atom. Hence a low T1,ads/T1,bulk ratio indicates a stronger surface interaction. The carbon atoms associated with unsaturated bonds in the molecules are seen to exhibit a larger reduction in T1 on adsorption relative to the aliphatic carbons, consistent with adsorption occurring through the carbon-carbon multiple bonds. The relaxation data are interpreted in terms of proximity of individual carbon atoms to the alumina surface and adsorption conformations are inferred. Furthermore, variations of interaction strength and molecular configuration have been explored as a function of adsorbate coverage, temperature, surface pre-treatment, and in the presence of co-adsorbates. This relaxation time analysis is appropriate for studying the behaviour of hydrocarbons adsorbed on a wide range of catalyst support and supported-metal catalyst surfaces, and offers the potential to explore such systems under realistic operating conditions when multiple chemical components are present at the surface.

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Monitoring the stability of nanosized silica dispersions in presence of polycations by a novel centrifugal sedimentation method

Petzold

Goltzsche

Mende

et al. 2009

J of Applied Polymer Sci

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The stability of Aerosil-silica dispersions is analyzed in dependence on the addition of polycations with different charge density and hydrophobic modification using the analytical centrifuge LUMiSizer. This novel centrifugal sedimentation method allows the direct calculation of the stability parameters like sedimentation velocity and prediction of the shelf life. The highly charged polycation poly (diallyl-dimethylammonium chloride) (PDADMAC) is compared with tailored cationic polyelectrolytes of equal degree of polymerization but lower and different charge density as well as various hydrophobic substitutions. The used technique allows to accelerate demixing and to quantify the stability of dispersions in a direct way. All polymers under study are able to stabilize aerosil dispersions, but the shelf life strongly depends on the polymer concentration. Typically for polycations, the stability increases with the polymer concentration whereas at low-polymer content flocculation can be detected. In this context, the behavior of PDADMAC and three cationic PVB derivatives is similar, but, whereas the stability of PDADMAC containing dispersions decreases at higher polymer concentrations, PVB derivatives are effective stabilizers at hi-her concentrations too. The highest increase of the stability with increasing polymer concentration is obtained with the ampholytic terpolymer TP that has the lowest cationic charge

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13C NMR study of the influence of the Aerosil surface charge on the short-chain surfactant adsorption

Cited by 6 publications

References 27 publications

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

Determining adsorbate configuration on alumina surfaces with ¹³C nuclear magnetic resonance relaxation time analysis

Monitoring the stability of nanosized silica dispersions in presence of polycations by a novel centrifugal sedimentation method

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13C NMR study of the influence of the Aerosil surface charge on the short-chain surfactant adsorption

Cited by 6 publications

References 27 publications

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

An Insight into the Role of Reactant Structure Effect in Pd/C Catalysed Aldehyde Hydrogenation

Determining adsorbate configuration on alumina surfaces with 13C nuclear magnetic resonance relaxation time analysis

Monitoring the stability of nanosized silica dispersions in presence of polycations by a novel centrifugal sedimentation method

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Determining adsorbate configuration on alumina surfaces with ¹³C nuclear magnetic resonance relaxation time analysis