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Author(s): N. C. Barnard & S. G. R. Brown
Abstract:
Raney nickel-aluminium alloys are widely used in powder form as catalysts for
hydrogenation reactions.
While the catalytic powder may be produced via
several processing routes in this paper we are concerned with powders
manufactured via spray atomization of liquid metal.
Before use, the powdered
nickel-aluminium alloy undergoes a leaching process carried out in sodium
hydroxide solution which dissolves aluminium from the solid and leaves a
nanoscopically porous nickel rich product.
This product is sometimes referred to
as ‘spongy nickel’.
The kinetics of the process is governed by both the rate of
dissolution of aluminium into solution and the rate of surface diffusion of the
nickel (which promotes the formation of the nanoscopically porous material).
However, individual powder particles may contain more than one NiAl phase.
Of
particular interest to this work are the NiAl3 and Ni2Al3 phases.
This paper
describes a preliminary attempt to model the leaching behaviour of these two
phases using a kinetic Monte Carlo simulation.
Keywords: Raney-Ni, leaching, spray-atomization, kinetic Monte Carlo.
1 Introduction:
Raney-type nickel catalysts have been used extensively in hydrogenation
reactions, owing to their high catalytic activity in organic reactions.
Raney-type
Nickel catalysts are obtained from Ni-Al alloys, whereby a large proportion of
the aluminium present is removed via caustic action: immersion in concentrated
NaOH solution.
The starting composition of the Ni-Al alloy and the leaching
time/condition has been shown to have an impact on the structure and catalytic
performance of the Raney-Ni product [1-5].
Traditionally, the composition used
...
Pages: 10
Size: 3,496 kb
Paper DOI: 10.2495/ECOR070061
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