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5. Au–Pd separation enhances bimetallic catalysis of alcohol oxidation

Author

Huang, Xiaoyang, Akdim, Ouardia, Douthwaite, Mark, Wang, Kai, Zhao, Liang, Lewis, Richard J., Pattisson, Samuel, Daniel, Isaac T., Miedziak, Peter J., Shaw, Greg, Morgan, David J., Althahban, Sultan M., Davies, Thomas E., He, Qian, Wang, Fei, Fu, Jile, Bethell, Donald, McIntosh, Steven, Kiely, Christopher J., and Hutchings, Graham J.

Published
2022
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12. From support to carbocatalyst : the aerobic and solvent free epoxidation of dec-1-ene using graphitic oxide as a catalyst

Author

Pattisson, Samuel David

Subjects
547, QD Chemistry
Abstract

The solvent-free selective epoxidation of dec-1-ene has been achieved under mild conditions and using atmospheric oxygen as the sole oxidant. Furthermore this has been conducted in the absence of radical initiators which is a first for such an oxidation to the best of our knowledge. The selective epoxidation of alkenes typically requires the use of supported active metals such as gold or silver. These have been studied for the epoxidation of dec-1-ene however they were found to be inactive in the absence of radical initiators. Alternatively, this transformation has been achieved using a graphitic oxide catalyst which harbours no active metal species. This is yet another remarkable example of the potential of carbocatalysis for green chemistry. The commonly raised issues when using carbocatalysts such as identification of active species and presence of impurities are addressed. A range of graphitic oxides have been produced using modified Hofmann and Hummers methods with attention given to the effect of amount of oxidant used compared to commonly employed literature standards. We conclude that the popular highly oxidised Hummers materials used in the bulk production of graphene may not be the optimum material for all applications and that specification of graphitic oxides may be required to suit each application. An investigation of activity in the epoxidation of dec-1-ene partnered with a full characterisation of the surface suggests that an optimum level of oxidation is required along with the need for a surface free of potential poisons such as sulphur. We also evaluate the current methods used in the preparation and separation of these materials and suggest that for applications such as epoxidation alternative techniques may be required in order to realise its potential as a carbocatalyst. This work provides the basis for the development of an efficient catalyst for the selective epoxidation of α-alkenes, eradicating the need for expensive stoichiometric reagents or toxic radical initiators.

Published
2015

17. Investigating Periodic Table Interpolation for the Rational Design of Nanoalloy Catalysts for Green Hydrogen Production from Ammonia Decomposition

Author

Parker, Luke A., primary, Richards, Nia, additional, Bailey, Liam, additional, Carter, James H., additional, Nowicka, Ewa, additional, Pattisson, Samuel, additional, Dummer, Nicholas F., additional, He, Qian, additional, Lu, Li, additional, Kiely, Christopher J., additional, Golunski, Stanislaw E., additional, Roldan, Alberto, additional, and Hutchings, Graham J., additional

Published
2023
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20. Enhancing the understanding of the glycerol to lactic acid reaction mechanism over AuPt/TiO2 under alkaline conditions.

Author

Evans, Christopher D., Douthwaite, Mark, Carter, James H., Pattisson, Samuel, Kondrat, Simon A., Bethell, Donald, Knight, David W., Taylor, Stuart H., and Hutchings, Graham J.

Subjects
LACTIC acid, GLYCERIN, HETEROGENEOUS catalysts
Abstract

The oxidation of glycerol under alkaline conditions in the presence of a heterogeneous catalyst can be tailored to the formation of lactic acid, an important commodity chemical. Despite recent advances in this area, the mechanism for its formation is still a subject of contention. In this study, we use a model 1 wt. % AuPt/TiO2 catalyst to probe this mechanism by conducting a series of isotopic labeling experiments with 1,3-13C glycerol. Optimization of the reaction conditions was first conducted to ensure high selectivity to lactic acid in the isotopic labeling experiments. Selectivity to lactic acid increased with temperature and concentration of NaOH, but increasing the O2 pressure appeared to influence only the rate of reaction. Using 1,3-13C glycerol, we demonstrate that conversion of pyruvaldehyde to lactic acid proceeds via a base-promoted 1,2-hydride shift. There was no evidence to suggest that this occurs via a 2,1-methide shift under the conditions used in this study. [ABSTRACT FROM AUTHOR]

Published
2020
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21. Lowering the Operating Temperature of Gold Acetylene Hydrochlorination Catalysts Using Oxidized Carbon Supports

Author

Pattisson, Samuel, primary, Dawson, Simon R., additional, Malta, Grazia, additional, Dummer, Nicholas F., additional, Smith, Louise R., additional, Lazaridou, Anna, additional, Morgan, David J., additional, Freakley, Simon J., additional, Kondrat, Simon A., additional, Smit, Joost J., additional, Johnston, Peter, additional, and Hutchings, Graham J., additional

Published
2022
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23. Selective oxidation of methane to methanol and methyl hydroperoxide over palladium modified MoO3 photocatalyst under ambient conditions

Author

Sun, Songmei, primary, Dummer, Nicholas F., additional, Bere, Takudzwa, additional, Barnes, Alexandra J., additional, Shaw, Greg, additional, Douthwaite, Mark, additional, Pattisson, Samuel, additional, Lewis, Richard J., additional, Richards, Nia, additional, Morgan, David J., additional, and Hutchings, Graham J., additional

Published
2022
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25. Frontispiece: A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

Author

Najafishirtari, Sharif, primary, Friedel Ortega, Klaus, additional, Douthwaite, Mark, additional, Pattisson, Samuel, additional, Hutchings, Graham J., additional, Bondue, Christoph J., additional, Tschulik, Kristina, additional, Waffel, Daniel, additional, Peng, Baoxiang, additional, Deitermann, Michel, additional, Busser, G. Wilma, additional, Muhler, Martin, additional, and Behrens, Malte, additional

Published
2021
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26. A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

Author

Najafishirtari, Sharif, primary, Friedel Ortega, Klaus, additional, Douthwaite, Mark, additional, Pattisson, Samuel, additional, Hutchings, Graham J., additional, Bondue, Christoph J., additional, Tschulik, Kristina, additional, Waffel, Daniel, additional, Peng, Baoxiang, additional, Deitermann, Michel, additional, Busser, G. Wilma, additional, Muhler, Martin, additional, and Behrens, Malte, additional

Published
2021
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30. Sulfur Promotion in Au/C Catalyzed Acetylene Hydrochlorination

Author

Dawson, Simon R., primary, Pattisson, Samuel, additional, Malta, Grazia, additional, Dummer, Nicholas F., additional, Smith, Louise R., additional, Lazaridou, Anna, additional, Allen, Christopher S., additional, Davies, Thomas E., additional, Freakley, Simon J., additional, Kondrat, Simon A., additional, Kiely, Christopher J., additional, Johnston, Peter, additional, and Hutchings, Graham J., additional

Published
2021
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33. Effect of the Preparation Method of LaSrCoFeOx Perovskites on the Activity of N2O Decomposition.

Author

Richards, Nia, Parker, Luke A., Carter, James H., Pattisson, Samuel, Morgan, David J., Dummer, Nicholas F., Golunski, Stanislaw E., and Hutchings, Graham J.

Subjects
CATALYSTS, BOND strengths, CITRIC acid, GLOBAL warming, SURFACE recombination, LOW temperatures
Abstract

N2O remains a major greenhouse gas and contributor to global warming, therefore developing a catalyst that can decompose N2O at low temperatures is of global importance. We have investigated the use of LaSrCoFeOx perovskites for N2O decomposition and the effect of surface area, A and B site elements, Co–O bond strength, redox capabilities and oxygen mobility have been studied. It was found that by using a citric acid preparation method, perovskites with strong redox capabilities and weak Co–O bonds can be formed at relatively low calcination temperatures (550 °C) resulting in highly active catalysts. The enhanced activity is related to the presence of highly mobile oxygen species. Oxygen recombination on the catalyst surface is understood to be a prominent rate limiting step for N2O decomposition. Here the reduced strength of Co–O bonds and mobile lattice oxygen species suggest that the surface oxygen species have enhanced mobility, aiding recombination, and subsequent regeneration of the active sites. La0.75Sr0.25Co0.81Fe0.19Ox prepared by citric acid method converted 50% of the N2O in the feed (T50) at 448 °C. [ABSTRACT FROM AUTHOR]

Published
2022
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34. Tuning graphitic oxide for initiator- and metal-free aerobic epoxidation of linear alkenes

Author

Pattisson, Samuel, Nowicka, Ewa, Gupta, Upendra N., Shaw, Greg, Jenkins, Robert L., Morgan, David J., Knight, David W., and Hutchings, Graham J.

Subjects
Science
Abstract

Graphitic oxide has potential as a carbocatalyst for a wide range of reactions. Interest in this material has risen enormously due to it being a precursor to graphene via the chemical oxidation of graphite. Despite some studies suggesting that the chosen method of graphite oxidation can influence the physical properties of the graphitic oxide, the preparation method and extent of oxidation remain unresolved for catalytic applications. Here we show that tuning the graphitic oxide surface can be achieved by varying the amount and type of oxidant. The resulting materials differ in level of oxidation, surface oxygen content and functionality. Most importantly, we show that these graphitic oxide materials are active as unique carbocatalysts for low-temperature aerobic epoxidation of linear alkenes in the absence of initiator or metal. An optimum level of oxidation is necessary and materials produced via conventional permanganate-based methods are far from optimal.

Published
2016

40. Selective oxidation of methane to methanol and methyl hydroperoxide over palladium modified MoO3photocatalyst under ambient conditionsElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2cy00240j

Author

Sun, Songmei, Dummer, Nicholas F., Bere, Takudzwa, Barnes, Alexandra J., Shaw, Greg, Douthwaite, Mark, Pattisson, Samuel, Lewis, Richard J., Richards, Nia, Morgan, David J., and Hutchings, Graham J.

Abstract

Selective partial oxidation of methane to valuable oxygenated products remains a great challenge, as typically over oxidation of oxygenated products to COxis observed. Weak oxidative species on the catalyst surface have a great potential to overcome this limitation. However, weak oxidative species usually have low concentrations and are easily decomposed. Here we report a Pd/MoO3photocatalyst which can realize excellent methane oxidation to methanol and methyl hydroperoxide in pure water, under simulated solar light by in situgenerated H2O2at room temperature and pressure. The combined selectivity for methanol and methyl hydroperoxide is up to 98.6%, representing a productivity rate of 42.5 μmol gcat−1h−1. Further studies on the reaction mechanism indicate that PdO species on the Pd loaded MoO3catalyst play an essential role in the suppression of over oxidation. In this case PdO traps the photo-generated electrons, leaving photo-generated holes for decomposition of H2O2into weak oxidative hydroperoxyl radicals which are not involved in the formation of over oxidation products.

Published
2022
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48. The role of Mg(OH)2 in the so-called 'base-free' oxidation of glycerol with AuPd catalysts

Author

Fu, Jile, He, Qian, Miedziak, Peter J., Brett, Gemma Louise, Huang, Xiaoyang, Pattisson, Samuel, Douthwaite, Mark, and Hutchings, Graham John

Abstract

Mg(OH)2 and Mg(OH)2 containing materials can provide excellent performance as supports for AuPd nanoparticles for oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the support's surface. However, its influence on the reaction solution is not generally discussed. In this paper, we examine, in detail, the relationship between the basic Mg(OH)2 support and AuPd nanoparticles using four types of catalyst, where the physical interaction between Mg(OH)2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH)2 added under base-free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH)2 affected glycerol oxidation, detailed information about the performance of AuPd/Mg(OH)2, physically mixed (AuPd/C+Mg(OH)2) and (AuPd/C+NaHCO3) was obtained and compared. Furthermore, NaOH and Mg(OH)2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH)2 supported catalysts in base-free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol which is considered to be the rate determining step in the reactionperformance of Mg(OH)2 supported catalysts in base-free condition could be correlated to its ability to affect the pH during the reaction.

Published
2017

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