Titania surface chemistry and its influence on supported metal catalysts

Mahdavi‐Shakib, Akbar; Husremovic, Samra; Ki, Sohee; Glynn, Jessica; Babb, Lauren; Sempel, Janine; Stavrinoudis, Ioannis; Arce‐Ramos, Juan Manuel; Nelson, Raymond J.; Grabow, Lars C.; Schwartz, Thomas J.; Frederick, B.G.; Austin, Rachel N.

doi:10.1016/j.poly.2019.05.012

Cited by 15 publications

(43 citation statements)

References 58 publications

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“…16,17,18 Especially TiO2 is extensively studied due to the possibilities it offers for the synthesis of a large variety of nano-morphologies and its applications in a wide range of fields. [19][20][21][22] Different precursors can be used for grafting transition metal oxides such as organosilanes, organophosphonic acids, carboxylic acids, alcohols and Grignard reagents. 23,24,25,26 Whereas organosilanes are the most applied precursors for surface grafting, in particular for SiO2, they are less applicable to TiO2 and ZrO2, as the poor hydrolytic stability of Ti-O-Si and Zr-O-Si bonds results in a rapid leaching of the organic layer.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and computational insights into the aminopropylphosphonic acid modification of mesoporous TiO2 powder: The role of the amine functionality on the surface interaction and coordination

Gys

Siemons

Pawlak

et al. 2021

Applied Surface Science

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Recently, interest has been directed towards the grafting of metal oxides with organophosphonic acids bearing terminal amine groups to extend the functionality and applicability of these materials. Previous reports mainly focus on the application perspective, while a detailed characterization of the surface properties at the molecular level and the correlation with the synthesis conditions are missing. In this work, mesoporous TiO2 powder is grafted with 3-aminopropylphosphonic acid (3APPA) under different concentrations (20, 75, 150 mM) and temperatures (50, 90 °C) and compared with propylphosphonic acid (3PPA) grafting to unambiguously reveal the impact of the amine group on the surface properties. A combination of complementary spectroscopic techniques and Density Functional Theory -Periodic Boundary Conditions (DFT/PBC) calculations are used. At 90 °C and high concentrations, lower modification degrees are obtained for 3APPA compared to Revised manuscript (unmarked) ick ere t vie inked Re erences 2 3PPA, due to amine-induced surface interactions. Both X-ray Photoelectron Spectroscopy (XPS) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy reveal that both NH2 and NH3 + groups are present, with also contributions of NH2 groups involved in hydrogen bonding interactions. A similar ratio of NH2/NH3 + (65:35) is obtained irrespective of the modification conditions, suggesting similar relative contributions of different surface conformations. Calculated adsorption energies from DFT calculations on 3APPA adsorption on anatase (101) in relation to the water coverage reveals a coexistence of various structures with the amine group involved in intra-adsorbate, inter-adsorbate and adsorbate-surface interactions. Further validation is obtained from the strong overlap of different 31 P environments represented by the broad band (35-12 ppm) in experimental 31 P Nuclear Magnetic Resonance (NMR) spectra and calculated 31 P chemical shifts of all modelled monodentate and bidentate structures. Structures related to the tridentate binding mode are not formed due to geometric restrictions of the anatase (101) facet applied as model support in the calculations. Nevertheless, they could be present in the experimental samples as they are composed of anatase (representing multiple crystal facets) and an amorphous titania fraction.

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Section: Introductionmentioning

confidence: 99%

“…This article aims to elucidate the impact of the amine group on the grafting of 3APPA on mesoporous TiO2 (Hombikat M311) and the obtained surface properties. Using propylphosphonic acid (3PPA) as amine-free analogue and, through grafting at different concentrations (20,75,150…”

Section: Introductionmentioning

confidence: 99%

Experimental and computational insights into the aminopropylphosphonic acid modification of mesoporous TiO2 powder: The role of the amine functionality on the surface interaction and coordination

Gys

Siemons

Pawlak

et al. 2021

Applied Surface Science

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“…Three main bands can be observed on FTIR spectra of catalysts: broad stretching band corresponding to surface O-H bonds around 3300 cm -1 , a small band at 1625 cm -1 corresponding to adsorbed water, and an intense band between 400 and 500 cm -1 corresponding to Ti-O-Ti stretching bond. 38,39 Spectra corresponding to TiO2 and corresponding to Ru/TiO2 are identical. However, the comparison of TiO2-A and TiO2-R spectra shows some differences: the band corresponding to adsorbed water at 1625 cm -1 is only visible on TiO2-A, indicating that this support is more favourable to water adsorption, i.e.…”

Section: Catalysts Preparation and Characterizationmentioning

confidence: 93%

“…Moreover, electronic vacancies on the surface of TiO2, and particularly on TiO2 anatase, creates strong Lewis acid sites, which can also form Brønsted acid sites in the presence of adsorbed water. 38,41 Potentiometric titration of TiO2-A and TiO2-R supports was performed to evaluate their acidity. This method has the advantage to measure acid sites in the presence of liquid water, therefore in environmental conditions close to the reaction.…”

Section: Catalysts Preparation and Characterizationmentioning

confidence: 99%

Unexpected reactivity related to support effects during xylose hydrogenation over ruthenium catalysts

Vilcocq

Paez

Freitas

et al. 2021

Preprint

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Xylose is a major component of hemicelluloses. In this paper, its hydrogenation to xylitol in aqueous medium was investigated with two Ru/TiO2 catalysts prepared with two commercial TiO2 supports. A strong impact of support on catalytic performances was evidenced. Ru/TiO2-R led to fast and selective conversion of xylose (100 % conversion in 2 h at 120°C with 99 % selectivity) whereas Ru/TiO2-A gave a slower and much less selective transformation (58 % conversion in 4 h at 120°C with 17 % selectivity) with the formation of several by-products. Detailed characterization of catalysts with ICP, XRD, FTIR, TEM, H2 chemisorption, N2 porosimetry, TPR and acid-base titration were performed to elucidate the role of each support. TiO2-R has a small specific surface area with large ruthenium nanoparticles in weak interaction with TiO2 support and no acidity, whereas TiO2-A is a mesoporous material with a large specific surface area, mildly acidic, and bears small ruthenium particles in strong interaction with TiO2 support. The former was very active and selective for xylose hydrogenation to xylitol whereas the latter was less active and poorly selective. Moreover, careful analysis of reaction products also revealed that TiO2 anatase can catalyze undesired side-reactions such as xylose isomerisation to various pentoses, and therefore the corresponding unexpected polyols (arabitol, ribitol) were produced during xylose conversion by hydrogenation. In a first approach of the kinetics, a simplified kinetic model was built to compare quantitatively intrinsic reaction rates of both catalysts. The kinetic constant for hydrogenation was 20 times higher for Ru/TiO2-R at 120°C.

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“…These materials has a high specific surface area, high mechanical and hydrothermal stability, narrow pore size distribution and available pore volume. PMOs normally be achieved through co-condensation of bridged organosilane precursors [(R′O)3Si-R-Si(OR′)3; R: organic bridging group, R′: methyl or ethyl to produce organofunctionalized ordered periodic mesoporous organosilica materials [1,2].…”

Section: Introductionmentioning

confidence: 99%

New magnetic periodic mesoporous organosilica functionalized 3-propyl amine (Fe3O4@PMO-ICS-PrNH2) as highly eﬃcien and recyclable catalysts in one-pot synthesis of imidazopyrimidine derivatives

Dekamine

Akbari

2019

Proceedings of the 23rd International Electronic Conference on Synthetic Organic Chemistry

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The catalytic application of a novel magnetic periodic mesoporous organosilica functionalized 3-propylamine(Fe3O4@PMO-ICS-PrNH2) in the synthesis of imidazopyrimidine derivatives was investigated. At first, the Fe3O4@PMO-ICS-PrNH2 nanocatalyst was prepared and characterized by N2 adsorption-desorption isotherms techniques, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer (VSM). Then, the catalyst was shown to be a efficient recyclable and highly active catalyst and used in the three-component synthesis of 2-aminobenzaldehyde with aromatic aldehydes various and dimedone/malononitrile under H2O solvent conditions. Also, imidazopyrimidine products were obtained in mild reaction conditions, good to excellent yields and at short reaction times.Moreover, the catalyst was recovered and successfully reused at least five times without considerable reduction in its activity.

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Titania surface chemistry and its influence on supported metal catalysts

Cited by 15 publications

References 58 publications

Experimental and computational insights into the aminopropylphosphonic acid modification of mesoporous TiO2 powder: The role of the amine functionality on the surface interaction and coordination

Experimental and computational insights into the aminopropylphosphonic acid modification of mesoporous TiO2 powder: The role of the amine functionality on the surface interaction and coordination

Unexpected reactivity related to support effects during xylose hydrogenation over ruthenium catalysts

New magnetic periodic mesoporous organosilica functionalized 3-propyl amine (Fe<sub>3</sub>O<sub>4</sub>@PMO-ICS-PrNH<sub>2</sub>) as highly eﬃcien and recyclable catalysts in one-pot synthesis of imidazopyrimidine derivatives

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