Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Search for a Raney-Ni type catalyst efficient in the transformation of
excess glycerol into more valuable products
Sz. Mészáros , J. Halász , Z. Kónya a,b, Pál Sipos c,d, I. Pálinkó d,e,
a
a
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a
Department of Applied and Environmental Chemistry, University of Szeged, Rerrich B. tér 1, Szeged, H-6720, Hungary
MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Rerrich B. tér 1, Szeged, H-6720, Hungary
Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary
Material and Solution Structure Research Group, Institute of Chemistry, University of Szeged, Szeged, H-6720, Hungary
Department of Organic Chemistry, University of Szeged, Dóm tér 8, Szeged, H-6720, Hungary
b
c
d
e
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 July 2013
Received in revised form 16 September 2013
Accepted 18 September 2013
Available online 2 October 2013
Al- and Si-containing Raney-Ni catalysts have been prepared with a method, which uses significantly less
NaOH than the one described in the original recipe, i.e., with method benign to the environment. The cata-
lysts were characterised by a variety of techniques (X-ray diffractometry, thermal methods, and BET surface
area measurements). The samples were used in transforming glycerol into more useful products. They were
found to be highly active and selective in producing acetol, a compound of current interest. Nevertheless, only
the silicon-containing sample behaved as a real catalyst, i.e. it could be regenerated and recycled. The Al-
containing samples were decomposed to intermetallic- and Al-(oxy)hydroxide phases during the reaction.
© 2013 Elsevier B.V. All rights reserved.
Keywords:
Non-pyrophoric Raney-type Ni catalysts
Characterisation by XRD, thermal and BET
measurements
Transformations of glycerol
Reuse and recycling possibilities
1
. Introduction
The traditional Raney-Ni belongs to the group of skeletal catalysts
may be listed. However, mineral acids destroy the skeletal system and
high Al content also decreases its stability.
The source of the skeletal catalysts is an alloy of a catalytically active
and an inactive metal. The latter component is dissolved fully or at least
partially, usually in a base. The primary particle diameter usually falls in
the 40–80 Å range. It is larger by one order of magnitude for catalysts
that were prepared from metal salts by thermal decomposition [1].
The precursor of the Raney-Ni catalyst is a 1:1 alloy of Ni and Al. The
Al content is dissolved in a solution containing 20–25 wt.% NaOH. This
is an exothermic reaction and is performed slowly under carefully con-
trolled conditions. In the final step, the product is washed until neutral.
The Ni content of the resulting material is 90–95%, and it is a sponge-like
fine powder with high specific surface area and pyrophoric property. As
it has already been mentioned the pyrophoric nature is disadvanta-
geous, and its elimination without losing catalytic activity is really chal-
lenging. Although thermal desorption or chemical/electrochemical
oxidation of the hydrogen or the combination of the two methods
resulted in non-pyrophoric catalysts, the catalytic activities were
found to significantly decrease as well [12,13].
Not too long ago Petró et al. were successful in the synthesis of a
novel non-pyrophoric, ferromagnetic Raney-Ni catalyst with activity
similar or higher in liquid-phase reactions than the traditional
Raney-Ni [14]. The starting material is a 50–50 wt.% Al–Ni alloy and
the resulting one is an aluminium-supported catalyst with well-
dispersed Ni of 25–30 wt.%. The innovation is the use of more dilute
base than usual, therefore the inactive component is just partially
providing comparable activity to noble metal catalysts under signifi-
cantly milder conditions (low temperature and pressure), thus avoiding
unwanted side reactions [1]. The Raney-type catalysts are widely used
for hydrogenation of various unsaturated compounds (for a review,
see [2]) like olefins [3], nitriles [4], oxo [5] and nitro compounds [6],
the C\S bond to C\H [7], to mention just a few, both in the laboratory
as well as in the fine chemical industry [8–10]. Raney-Ni obtained via
the original recipe [11] is highly pyrophoric due the absorbed hydrogen
in the pores of the catalyst. It is advantageous on one hand, since it is the
source of its high activity; however, it is a disadvantage on the other
hand, because of the high risk of setting the reacting system ablaze. To
avoid it the catalyst is kept under water and it is used in the form of
aqueous slurry making its use in the catalysis of organic reactants
tedious. The catalyst is still widely used, since the advantageous
properties override the disadvantageous ones. Besides those already
mentioned, among the advantages the relatively high density resulting
in favourable sedimentation ability, high heat conductivity, good ther-
mal and structural stabilities and low solubility in most organic solvents
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Corresponding author at: Department of Organic Chemistry, University of Szeged,