The growth and characterisation of supported metal catalysts prepared by novel chemical vapour deposition methods

Hussain, SZ 2008, The growth and characterisation of supported metal catalysts prepared by novel chemical vapour deposition methods , PhD thesis, University of Salford.

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Abstract

A novel TCVD procedure was employed for the preparation for the preparation of supported gold catalysts using dimethyl gold acetylacetonates Me 2 Au(acac) as the volatile precursor. Preliminary experiments on the use of TCVD for the preparation of copper catalysts from copper acetylacetonate Cu(acac) were also performed. The reactor design and the preparation protocol employed were used for the first time during current investigation. The impact of calcination conditions, system vacuum along with different pretreatments have been reported for better understanding of TCVD procedure. Similarly CCVD have been presented for the first time as an alternative procedure for the preparation of highly effective, uniformly dispersed supported Au, Cu and Ag catalysts, using environment friendly(HAuC! 4 , Cu(NO 3 )2, AgNO 3 ) cost effective, readily available precursors. The most important parameters like rate of nebulization, frequency of mixing, total number of passes, equivalent ratio, and the growth temperature along with their impact on resulting catalysts is also presented. A significant part was also dedicated to compare liquid phase methods with thermal and combustion chemical vapour deposition with focus on the liquid phase methods in general and deposition precipitation in particular. The effects of variant reaction conditions, like pH of precipitation, effects of support, and the influence of other related parameters will also be discussed. Particular attention was given to CO oxidation reactor which was constructed specifically for the present work. Also described are the analysis of the gold silver or copper contents of the catalysts and operation of the CO oxidation reactor (including the safety procedure with regard to CO reactor). For catalyst characterisation various analytical techniques used in this present work were X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic absorption (AA) analysis. Based on present investigation TCVD procedure can be regarded as effective as DP for the preparation of highly active Au/TiO 2 (T 50 239K) catalysts. The novelty of TCVD lies in its ability to successfully anchor Au on inert (A1 2 O 3 ) supports. An interesting feature of present study was the successful use of a high and low surface area supports the samples prepared using the high surface area support like TiO 2 were more active than the lower surface area. For supported silver and copper catalysts the samples prepared by CCVD, when compared with traditional preparation procedures were noticed to equally effective. Therefore presenting CCVD as an alternative procedure for traditional supports like TiO 2 in general and inert supports i.e., A1 2 O 3 , SiO 2 , in particular. During present work we were unable to prepare highly active supported Au catalysts, possibly due chloride impurities. Finally based on large number of experiments TCVD and CCVD can be regarded as highly effective, innovative, alternative preparation procedure with enormous potential for the surface treatment of powders in general and catalysts in particular.

Item Type: Thesis (PhD)
Contributors: Pemble, ME (Supervisor)
Schools: Schools > School of Computing, Science and Engineering
Depositing User: Institutional Repository
Date Deposited: 18 Aug 2021 13:24
Last Modified: 27 Aug 2021 21:57
URI: http://usir.salford.ac.uk/id/eprint/61614

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