Activation and Regeneration of Sponge Nickel Catalysts
Pavel Kukulaa, David Šturcb, and Petr Kačerc
Institute for Chemical and Bio-engineering, ETH Zurich, CH-8093 Zurich, Switzerland, pavel.kukula@chem.ethz.ch
Ranido Ltd, Kolářova 648/7, 143 00 Prague, Czech Republic , david.sturc@ranido.cz
c ICT Prague, Technická 5, 166 28 Prague, Czech Republic, petr.kacer@vscht.cz
a
b
Abstract
A general method for the regeneration of commercially available sponge nickel catalysts is presented. The developed procedure preserves or
increases the activity of used sponge nickel catalyst by in-situ catalyst treatment under mild conditions [1]. The catalyst is treated with the activator
ABX, which is inexpensive, non toxic and the consumption of which depends on the type of reaction. The scope of the regeneration procedure was
tested in several model hydrogenation reactions with sponge nickel as the standard hydrogenation catalyst. The results show that the regeneration
procedure can be applied advantageously in the hydrogenation of various functional groups. The regeneration procedure must, however, be
appropriately tuned for each hydrogenation reaction.
The Principle of the Regeneration Procedure
Reduction of Various Functional Groups
• in-situ treatment of the catalyst with activator ABX
• treatment conditions: room temperature, stirring in solvent
• activator concentration: 0.1-10 wt% of wet catalyst weight
• ketones to alcohols (cyclohexanone)
• aldehydes to alcohols (benzaldehyde)
• saccharides to polyols (D-ribose)
• nitriles to amines (acetonitrile)
• reduction of C=C bond (diethylfumarate)
• nitro compounds to amines (p-chloro-nitrobenzene)
• reductive amination (benzaldehyde with methyl amine)
Examples of Catalyst Regeneration
Reaction conditions: batch process; <55ºC; <20 bar; catalyst: sponge nickel (Degussa); S/Cwet ≥ 2; 0.2 mol substrate; 70-120 mL solvent (ethanol, water)
Re-activation conditions: amount of the activator ABX: 0.1-1 wt% of wet catalyst, stirring in ethanol for 30 minutes
+ H2
+ H2
RaNi
RaNi
25
O
HO
HO
15
10
5
D-ribose concentration [%]
20
20
15
10
0
5
● 2nd hydrogenation
(no activation)
5
10
15
20
25
time [min]
OH
+ H2
OH
OH
HO
RaNi
OH
OH
80
● 3rd hydrogenation
(no activation)
60
40
● 2nd hydrogenation
(no activation)
20
0
0
0
OH
100
25
hydrogen consumption [bar]
hydrogen consumption [bar]
OH
O
OH
O
0
10
20
30
40
50
tim e [m in]
0
20
40
60
80
100
tim e [min]
1st hydrogenation without activation
1st hydrogenation w ithout activation
1st hydrogenation w ithout activation
2nd-4th hydrogenation with activation (1.0 wt% ABX)
2nd hydrogenation w ithout activation
2nd hydrogenation w ithout activation
5th hydrogenation with activation (1.0 wt% ABX)
1st hydrogenation w ith activation (0.2 w t% ABX )
3rd hydrogenation w ithout activation
6th hydrogenation with activation (0.5 wt% ABX)
2nd hydrogenation w ith activation (0.3 w t% ABX)
8th hydrogenation with activation (1.0 % wt ABX)
5nd hydrogenation w ith activation (0.3 w t% ABX)
10nd hydrogenation w ith activation (0.3 w t% ABX)
Results
Activity: The catalyst treatment with the activator ABX preserves or increases catalyst activity in various hydrogenation reactions.
Activator concentration: Only small amounts of the activator ABX are required; there is an optimal value, at which the maximum catalytic activity
is obtained and, with increasing activator concentration (above optimum), catalyst activity decreases.
Mode of action: The activator removes the organic residues deposited on the catalyst after the reaction and, at the same time, it increases hydrogen availability.
Catalyst recycling: It is possible to re-use the catalyst up to 20 times.
Large scale application: Hydrogenation; 2000-litre autoclave; catalyst recycled 20 times [2].
Conclusions
A new method of re-activation and regeneration of sponge nickel catalysts was developed. The main advantages of this method are the following:
• Significant catalyst savings: catalyst can be re-used up to 20 times
• Improved or preserved catalytic activity: shorter reaction times; no or minimal decrease in conversion
• Improved selectivity: fewer by-products; higher yields
• Further technological advantages: easy applicability and increased safety of the hydrogenation process
References:
[1] http://www.ranido.cz; [2] Dr. Ivan Hlaváček, Interpharma Praha a.s., Komořanská 955, 143 10 Praha 12, Czech republic