|(19)||(11)||EP 2 012 919 B1|
|(12)||EUROPEAN PATENT SPECIFICATION|
|(45)||Mention of the grant of the patent: |
|11.12.2019 Bulletin 2019/50|
|(22)||Date of filing: 23.04.2007|
|(51)||International Patent Classification (IPC): |
|(86)||International application number: |
|(87)||International publication number: |
|WO 2007/125361 (08.11.2007 Gazette 2007/45)|
|(84)||Designated Contracting States: |
|AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR |
|(30)||Priority: ||28.04.2006 GB 0608359|
|(43)||Date of publication of application: |
|14.01.2009 Bulletin 2009/03|
|(73)||Proprietor: Johnson Matthey PLC|
|London EC4A 4AB (GB)|
- DALTON, James, Spencer
Berkshire RG4 6NL (GB)
|(74)||Representative: Lorkin, Thomas James Anthony et al|
|Johnson Matthey PLC
Royston SG8 5HE
Royston SG8 5HE (GB)
|(56)||References cited: : |
|EP-A2- 0 319 482|
US-A- 5 019 135
|US-A- 3 310 870|
US-A- 5 620 952
| || |
- T. MINOWA ET AL.: "HYDROGEN PRODUCTION FROM CELLULOSE USING A REDUCED NICKEL CATALYS", CATALYSIS TODAY, vol. 45, 31 December 1998 (1998-12-31), pages 411-416,
| || |
|Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).|
The present invention relates to a nickel slurry comprising a nickel sponge catalyst, water and additives to improve the flow behaviour of the nickel slurry.
Nickel sponge catalysts generally consist of milled polymorphic particles up to 20 micrometers in size. These particles are commonly sold in drums containing alkaline water and nickel at a weight ratio of approximately 90:85 (Ni:water). The catalyst must be contained in water as it is pyrophoric and can spontaneously combust if allowed to dry out in air. Such a catalyst in water system is known as a 'nickel slurry'.
Other compounds of nickel may be sold as catalysts for example nickel oxides, nickel halides, nickel complexes and nickel carbonyls but these are not generally provided as slurries.
Not all nickel compounds (including those listed above) will be suitable for use as a catalyst since certain properties of any material are key as to whether it is able to perform as a catalyst. Such properties include the requirement that the material has a clean surface and a high surface area thereby to enable the reactants to access the surface of the catalyst.
Nickel particles in a nickel slurry tend to settle within the container in which they are housed, e.g. a drum, due to the high density of nickel compared to water (density of nickel = 9 g cm-3
, density of water = 1 g cm-3
). These particles may even form a dense cake of sediment. Banging and vibration of the nickel slurry container, such as might occur during transportation, appears to make the cake more dense. The settling of the nickel catalyst makes it difficult to pour or remove from the drum, this poor flow behaviour being especially problematic due to the pyrophoric nature of the dry catalyst.
 WO 2006/063600
relates to adjusting catalysts' and catalyst precursors' suspension and settling properties using rheology modifiers, and concentrates on using rheology modifiers that speed up the rate of settling with nickel catalysts.
We have now found, surprisingly, that additives may be used to improve the flow behaviour of the nickel slurry without detrimentally affecting the activity of the nickel catalyst.
According to one aspect, the invention provides a nickel catalyst slurry comprising a nickel sponge catalyst which is pyrophoric when dry and which consists of milled polymorphic particles up to 20 micrometers in size, water and at least one rheology modifier, characterised in that said slurry exhibits pseudoplasticity, wherein said at least one rheology modifier is selected from the group consisting of polysaccharides, celluloses, hydrophobically modified alkali-swellable emulsions, polyhydroxycellulose derivatives and any combination thereof.
Rheology modifiers are used to alter the flow characteristics of a material. We have found that to improve the flowability of the nickel slurry, it was necessary to have a continuous dispersion with very high viscosity at low shear stress, and low viscosity at high shear stress. This is sometimes referred to as pseudoplasticity and results from the structure of the rheology modifier forming a network at low shear stress that breaks down under high shear stress. (Note the rheology modifiers used in this invention are used to modify the flow characteristics of the nickel slurry itself, not to modify the flow characteristics of the dry nickel catalyst prior to slurry formation.) These characteristics enable the nickel particles to be suspended when at rest, thereby avoiding the formation of a dense cake of catalyst, but also allow the viscosity of the solution to drop when being poured, enhancing flowability and allowing the catalyst to be readily transferred from its container. The at least one rheology modifier employed in the nickel catalyst slurries of the present invention is selected from the group consisting of polysaccharides, celluloses, hydrophobically modified alkali-swellable emulsions and polyhydroxycellulose derivatives and any combination thereof, such as Xanthan gum and Rheovis 152 (Ciba Speciality Chemicals).
A nickel slurry according to the invention may comprise from 1 x 10-3
wt% to 3 wt% rheology modifiers relative to the total weight of the slurry.
Typically the nickel slurry will be alkaline, e.g. pH = 11. We have found that Rheovis 152 is useful as a rheology modifier for nickel slurry as it is at its most efficient at approx. pH 11.
In order that the invention may be more fully understood the following Examples are provided by way of illustration only and with reference to the accompanying drawings, in which:
Figure 1 is a photograph of a sample of nickel slurry containing a rheology modifier, taken 16 hours after shaking.
Nickel Catalyst Sample Treated with Rheology Modifiers
46 grams of a nickel catalyst slurry was placed in a jar and shaken. To this slurry 0.16 grams of Xanthan gum (CP Kelco, Kelzan HP) was added and the contents of the jar stirred for 20 minutes. On cessation of stirring, the nickel particles did not form a sediment. Furthermore, 16 hours after cessation of stirring no sedimentation of nickel particles could be seen (see Figure 1).
The experiment described in Example 1a was repeated using 0.46 grams of Rheovis 152 (containing 0.18 grams active ingredient) in place of the Xanthan gum. Only a minimal amount of sedimentation was observed, directly after cessation of stirring and 16 hours later.
Comparative Activity of Treated Nickel Catalysts
A nickel catalyst sample prepared according to Example 1a was tested for its activity in a hydrogenation reaction. Catalytic hydrogenation converts a cyano-precursor into the corresponding methylamino substituent. Side products of the reaction may arise such as unknown materials, and secondary products from uncatalysed reactions of the product (see impurity 1 below).
Each catalyst sample was shaken to allow a representative sample to be taken, then 2 x 1.4 grams of suspended catalyst was weighed into 2 tubes. To each tube 1.0 grams of cyano-substituted precursor, 7 ml methanol and 0.1 ml '880' ammonia was added. The tubes were then sealed in a Baskerville multi-well autoclave and the apparatus purged three times with argon then 3 times with hydrogen before being pressurized to 4.5 bar hydrogen and heated to 40 °C. The reaction mixture in each of the tubes was stirred and heated under constant pressure of hydrogen (maintained by a Buchi press-flow controller) overnight, the apparatus was then allowed to cool under hydrogen and finally the pressure within the autoclave was vented and the samples recovered. Samples from each tube were filtered and diluted 1:1 with water for analysis by HPLC.
||YMC basic, 25 x 0.46cm|
||Either 33/67 MeOH/H2O|
||or 27/73 MeOH/H2O containing 0.005 M Na2HPO4|
|| acidified with H3PO4 to pH 2|
||Refractive index, 35°C|
|Sample||Product 1||Product 2||Starting Material||Impurity 1|
|Example 1a (unmodified)
|Example 1a (modified)
As can be seen the nickel catalyst sample treated with the rheology modifier did not show a reduced catalytic activity relative to the untreated sample. In fact the activity of the nickel catalyst sample treated with the rheology modifier appears to have increased, as evidenced by the increased conversion of starting material (note: Product 1 and Product 2 may be combined during further processing).
1. A nickel catalyst slurry comprising a nickel sponge catalyst which is pyrophoric when dry and which consists of milled polymorphic particles up to 20 micrometers in size, water and at least one rheology modifier, characterised in that said slurry exhibits pseudoplasticity, wherein said at least one rheology modifier is selected from the group consisting of polysaccharides, celluloses, hydrophobically modified alkali-swellable emulsions, polyhydroxycellulose derivatives and any combination thereof.
2. A nickel catalyst slurry according to claim 1 wherein the at least one rheology modifier is xanthan gum.
3. A nickel catalyst slurry according to claim 1 or 2, wherein the nickel slurry comprises from 1 x 10-3 wt% to 3 wt% rheology modifiers relative to the total weight of the slurry.
4. A nickel catalyst slurry according to claim 1, 2 or 3, wherein the nickel slurry is alkaline.
1. Nickelkatalysatorsuspension, die einen Nickelschwammkatalysator, der pyrophor ist, wenn er trocken ist, und der aus gemahlenen polymorphen Partikeln mit einer Größe von bis zu 20 Mikrometer besteht, Wasser und mindestens einen Rheologiemodifikator umfasst, dadurch gekennzeichnet, dass die Suspension Pseudoplastizität zeigt, wobei der mindestens eine Rheologiemodifikator aus der Gruppe bestehend aus Polysacchariden, Cellulosen, hydrophob modifizierten durch Alkali quellbaren Emulsionen, Polyhydroxycellulosederivaten und einer beliebigen Kombination davon ausgewählt ist.
2. Nickelkatalysatorsuspension nach Anspruch 1, wobei der mindestens eine Rheologiemodifikator Xanthan ist.
3. Nickelkatalysatorsuspension nach Anspruch 1 oder 2, wobei die Nickelsuspension von 1 x 10-3 Gew.-% bis 3 Gew.-% Rheologiemodifikatoren bezogen auf das Gesamtgewicht der Suspension umfasst.
4. Nickelkatalysatorsuspension nach Anspruch 1, 2 oder 3, wobei die Nickelsuspension alkalisch ist.
1. Suspension de catalyseur à base de nickel, comprenant un catalyseur de type éponge à base de nickel qui est pyrophorique lorsqu'il est sec et constituée par des particules polymorphes broyées de jusqu'à 20 µm en grosseur, par de l'eau et par au moins un agent de modification de la rhéologie, caractérisée en ce que ladite suspension présente une pseudoplasticité, ledit au moins un agent de modification de la rhéologie étant choisi dans le groupe constitué par les polysaccharides, les celluloses, les émulsions modifiées de manière hydrophobe, gonflables par les alcalis, les dérivés de polyhydroxycellulose et toute combinaison correspondante.
2. Suspension de catalyseur à base de nickel selon la revendication 1, ledit au moins un agent de modification de la rhéologie étant une gomme de xanthane.
3. Suspension de catalyseur à base de nickel selon la revendication 1 ou 2, la suspension à base de nickel comprenant de 1 x 10-3% en poids à 3% en poids d'agents de modification de la rhéologie par rapport au poids total de la suspension.
4. Suspension de catalyseur à base de nickel selon la revendication 1, 2 ou 3, la suspension à base de nickel étant alcaline.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description