Gold catalysts for liquid phase epoxidation of terminal alkenes: 1-decene and propene

Gatti, Marco Maria 2013. Gold catalysts for liquid phase epoxidation of terminal alkenes: 1-decene and propene. MPhil Thesis, Cardiff University. Item availability restricted.

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Abstract

Gold surfaces have long been regarded as inert and poor catalyst due to their highly stable chemical structures; nevertheless, it has been demonstrated that gold becomes extremely catalytically active when sizes are reduced to < 15 nm and synthesis are performed in the presence of 3d transition metal oxides [1]. The catalytic activity of gold is enhanced by metal oxide supports that have high oxygen mobility, such as TiO2, Fe2O3, NiOx and CoOx [2]. Also if gold is deposited as nanoparticles by co-precipitation or depositionprecipitation method, it becomes catalytically active for CO oxidation at temperature as low as 200 K [1]. In this project gold-supported catalyst has been used for the selective epoxidation of terminal alkenes, such as propene and 1-decene, in order to achieve higher conversions to propene and decene epoxides and to sustain an industrial development. Propene epoxide (PO) is an important intermediate in the chemical industry, and it is used for making propylene glycol, polyethers, glycerol and other products. Currently PO is produced by two in-direct processes that create a large amount of by-products, which are an environmental concern and expensive to dispose of. Therefore, a direct process would be preferred. The liquid-phase epoxidation of propene has been performed in a stainless steel 50 ml Parr autoclave. Standard reaction condition were: 3 barg of propene, 3 barg of oxygen, 24 barg of nitrogen, heated to 90 °C and stirred at 1200 rpm. Bimetallic catalysts composed of supported gold and palladium nanoparticles on titanium dioxide or graphite, synthesized by sol-immobilization method, are used for the direct epoxidation. The reaction is carried out in the presence of benzyl peroxide (BPO) as radical initiator. Various parameters, such as the solvent volume, amount of radical initiator, and catalyst composition, were changed in order to increase conversion and yield in propene epoxide. 1-decene is converted into 1,2-epoxydecane over graphite-supported copper, manganese and gold in the presence of sub-stoichiometric amounts of radical initiator (azobisisobutyronitrile, AIBN). The reaction has been performed in a round-bottom-flask reactor and variation of experimental parameters, such as oxygen pressure, speed of the stirrer, and reaction time, have been performed in order to determine the effects on conversion and selectivity upon epoxide or other terminal oxygenated-C10 products.

Item Type:	Thesis (MPhil)
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Date of First Compliant Deposit:	30 March 2016
Last Modified:	26 Oct 2017 09:54
URI:	https://orca.cardiff.ac.uk/id/eprint/58015

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