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

Hussain, SZ

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.

Citation

Hussain, S. The growth and characterisation of supported metal catalysts prepared by novel chemical vapour deposition methods. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Aug 18, 2021
• Award Date: Jun 1, 2008