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DEVELOPED
RANEY TYPE CATALYSTS
Activated Raney type catalysts are known for their high
activity at low temperatures and although used primarily for hydrogenation
reactions, they are also active for dehydrogenation, hydrogenolysis,
desulphurisation and dehalogenation of organics.
Examples of typical Nickel reaction include the reduction of:
1. D-glucose to sorbitol
2. Nitriles and nitro groups to amines
3. Ethylenic and acetylenic linkages
4. Exocyclic double bonds in an aromatic compound with or without saturation of
the nucleus
5. Aldehydes
6. Ketones
7. Pyridine
The production route has been specifically developed to impart enhanced activity
to the catalyst for the reduction of d-glucose, resulting in:
1. Increased reaction rate, improving plant throughput under the same
conditions.
2. Use of lower catalyst concentration, thus saving on catalyst costs and
improving process economics.
3. Use of milder reaction conditions, enhancing selectivity.
4. Various aspects of the catalyst have been examined in work on manufacturing
methods and the variation of properties.
These details will be discussed with users on a confidential basis.
Competitive and monopoly influences in the UK at the present time make
this approach essential.
RANEY TYPE METAL CATALYSTS
Nickel
Copper
Cobalt
The products are powders which are supplied and stored under water, or in other
suitable liquid.
On drying out in air the catalyst sparks and fires at red heat. This firework
like effect or pyrophoricity occurs spontaneously. Until and during use the
material must be maintained in a wet state.
For this reason and in case of spillage, the catalyst should be stored clear of
any materials which are combustible.
The use of nickel in fine particle catalytic form was invented by Raney in the
1920's. The properties have not really been developed since that time.
The catalyst is readily produced from an alloy of nickel and aluminium. The
aluminium is extracted from the alloy by various alkaline washing process.
The best qualities require special processing and are presented in this revised
publication. Environmental - provision is also made in Universals programme for
recovery of caustic arisings and studies are also in hand regarding the
problems of customers who are nickel users.
Wholely metal nickel catalysts are porous and this is the source of their
hetorogeneous catalytic properties in promoting hydrogenation and other
reactions on the large surface within the open structure. For example, benzene
can be converted to cyclohexane and glucose hydrolysed and hydrogenated to
polyols.
Nickel is the most widely used. Unspecified in terms of chemical and physical
properties by some manufacturers it has been suggested as a 'classic' material
with unalterable properties. There is considerable information, often
contradictory, to yet decide on such claims.
Co-operation by users of catalyst is necessary to determine the value of
variations in properties, for example the effect of supernatant pH. The wide
range of environments encountered in hydrogenation and other reactions are also
significant.
Copper is fundamentally different from nickel in its properties for specific
reaction while cobalt is largely unexplored because of cost.
The points raised in the attached gives interested customers the opportunity to
examine. requirements against technical features of their process.
APPLICATIONS
Activated nickel catalysts are known for their high activity at low
temperatures, and although used primarily for hydrogenation reactions, they are
also active for dehydrogenation, hydrogenolysis, desulphurisation and
dehalogenation of organics.
Examples of typical reactions include the reduction of:
* d-glucose to sorbitol
* Nitriles and nitro groups to amines
* Ethylenic and acetylenic linkages
* Exocyclic double bonds in an aromatic compound with or without saturation of
the nucleus
* Aldehydes
* Ketones
* Pyridine
The production route has been specifically developed to impart enhanced
activity to the catalyst for the reduction of d-glucose, resulting in:
* Increased reaction rate, improving plant throughput under the same conditions
* Use of lower catalyst concentration, thus saving on catalyst cost and
improving process economics.
* Use of milder reaction conditions, enhancing selectivity.
Special study
D Glucose and hydrogenolysis of carbohydrates using Nickel catalysis The
use of catalysts for the hydrogenation and hydrolysis of carbohydrates such as
glucose, presents no easy chemical study either theoretically or practically.
Total metal nickel catalysts and supported nickel and similar materials using
alumina, silica and magnesia can effect hydrogenolysis with degradation of
carbohydrates down to glycerols and simple alcohols.
Preparation procedures are simple particularly in the laboratory. Plant
manufacture presents special problems of control and the producer also has to
cater for the large volume of arisings or by-product.
Products made by carbohydrate catalysis.
* Glucosone
* Maltol
* Sorbitol
* Aminosorbitol
* D-mannitol
* Xylitol
* Glycerol
Catalyst modifications.
The use of various additives for catalyst materials is published in patents and
technical literature. These may be claimed to improve the specificity of the
reaction or other features such as activity, particle durability and so on;
additives include the following elements:-
* Various rare earths
* Transition metals
* Calcium, barium and strontium
* Titanium
* Iron
* Magnesium
* Molybdenum
* Chromium
Claims are made for the effect of modifiers in patents and literature. Very
little detailed quantitative data or explanations of possible mechanisms are
given.
Hence, there are problems of evaluation for users who are in the hands of the
catalyst supplier so far as materials are concerned. The catalyst supplier
forms opinions from user reports but cannot provide comprehensive data from the
many practicalities faced.
These notes apply mainly to nickel. Copper parallels nickel, in most of the
areas discussed here, but requires special consideration and can be readily
shown to have differing properties. This can be discussed with customers on an
individual basis.
Colour throw - in the processing of sugars we note there are nickel dissolution
problems. We are looking at ways to alleviate this problem and invite enquiries
from potential or existing customers.
PHYSIOCHEMICAL PROPERTIES
Atomic Weight: Nickel 58.69
Concentration of catalyst - as required by customer.
Boiling Point of suspending water - 100ºc
Specific Gravity of Nickel Matrix - 5.6 approx.
HSE Exposure Limit: HSE exposure limit and ACGIH TLV list 1983, Nickel
Metal 1 mg/m3. HIOSH Criteria Document (1977), recommended exposure limit of
0.015 mg/m3 in the air.
Auto Ignition (pyrophoricity): On drying in air sparks or fumes
according to conditions and temperature.
HYDROGEN RELEASE
Hydrogen may be evolved in storage. The rate and amount of this is dependent on
various factors and catalyst type.
Detailed information is available in our BATCH SPECIFICATION and analysis sheet
for purchasing customers.
Experience has shown that under ventilated storage at normal temperatures up to
20°C there is virtually no risk of explosion
QUALITY CONTROL AND TECHNICAL SERVICE
Activated nickel catalysts are produced under carefully controlled conditions,
which ensure consistency in both quality and performance.
Advice and assistance in product development and technical services are readily
available.
The basic features of catalysts are defined in relation to specific reactions.
More specific catalyst information is available to purchasing customers.
SURFACE CHEMISTRY
CATALYST ANALYSIS / FEEDBACK. The specification of heterogeneous catalyst
properties presents difficulties. Our examination of the published data and
claims made for aspects such as specificity of reaction do not have a firm
general or theoretical basis.
This is particularly the case when viewed from the catalyst manufacturers
perspective relative to the confidential practises of organic chemical
manufacturers.
The measurements of catalyst activity is a similarly difficult feature. Small
scale empirical laboratory testing is seldom practical for routine quality
control.
Measurement of catalyst surface characteristics by Universal test methods
has enabled a library of information to be built up.
Significant factors determining specification performance can be controlled.
These will be further refined against feedback data details of in process
results and requirements.
General considerations for users.
Please regard the information
given here as commercial and in confidence in view of monopoly positions in the
market
For the purposes of explanation two general catalytic protocols should be
considered to facilitate specification-
1. Basic quality or Classic catalyst.
2. Developed product.
Within the above categories there is considerable scope for chemical and
physical variations. Some aspects of these are outlined in this brochure.
Basic Catalyst
The problem the catalyst manufacturer faces is that of product specification in
relation to the feedback of data from customers plant and laboratory tests.
Minimal or loose specification is to the catalyst makers advantage. The
potential for developing and defining catalyst techniques is inhibited by lack
of feedback and the need for confidentiality by both producer and user.
More important however have been price cutting practises and the prohibitive
costs of research.
For a long time customers were provided with only skimpy detail in respect of
the many factors now being seen as worthy of closer examination.
Empirical testing with non-specific catalyst is not desirable from either the
catalyst producer or users point of view.
Plant results are the ultimate test of catalyst quality and specification.
Customers should not rely entirely on single shot activity tests in the
laboratory as the only guide.
In plant, separation of catalyst from product and other practical plant factors
are often more significant.
The Basic catalyst formulation available in relation to general customer requirements
or for initial or benchmark testing is of the following specification:-
Nickel (average dry basis) - 94% by wt
Aluminium or compounds (average dry basis) - 5% by wt as Al
Particle size- average of range - 10 to 40 microns (The particle size quoted
for catalysts varies according to the method of measurement)
pH- normal range - 10 to 11.
Catalytic activity - see next page.
1. pH - In practice the catalyst is supplied under water in view of its
pyrophoric nature. The pH quoted refers to the supernatant liquor. Low pH
material can be supplied subject to investigation with the customer.
2. Particle Size - this evaluation is subjective both in terms of the test
method used and interpretation of results. Customers should give details of
methods used to specify so that requirements are met on the basis of agreement.
3. Catalytic Activity - this refers to a test method- not involving hydrogen -
details of which can be given to customers who purchase catalyst. The degree of
exhaustion of most catalysts, after use or in store, may be determinable as
well as the activity of prime catalyst. Patenting is being considered.
Special equipment is not required beyond that normally available in a chemical
quality control laboratory.
Reagent solutions are available from UNIVERSAL Chemicals.
The interpretation of this test and its value will be discussed with purchasing
customers who are interested in this facility.
4. Variations in the characteristics given above for Basic or classic catalyst
are possible both within and outside the ranges stated.
Can you give provide comment on your requirements according to the following
features which we hope you will find helpful.
1. Aluminium content (dry or wet basis)
2. Nickel content (on same dry or wet basis)
3. Hence, from 1. and 2. nickel/aluminium ratio on weight basis.
4. Particle size range.
The above in concert with other considerations determines extraction method for
catalyst.
Comparison of pH specifications for classic nickel catalyst.
The following illustration indicates how the basic specification can be
modified in respect of alkali residuals in catalyst.
Ni. % Al. % Al as Al(OH)3 % Ratio Ni / Al. Universal Chemicals* 94 - 96 3 - 5
8.7 -14.4 24 Approx. Competitive 86 - 88 8-11 23.1 - 31.8 9 Approx. The range
of aluminium content shown here is a definitive minimal indicating what can be
supplied.
The above demonstrates a range of possibilities simply in respect of the basic
chemical composition of a nickel catalyst. At the extremes of aluminium content
the catalyst can be 10% higher in nickel and more active for a given weight.
The specification given against Universal should be regarded as the definitive
minimal alumina specification for nickel catalyst, at the present time.
The aluminium content can affect other properties in relation to the
environment in which the catalyst is used. High residual aluminium has been
claimed as beneficial provided it is in 'correct' form.
Catalyst can be supplied to any specification interested customers should
discuss this with Universal.
Because all catalyst production factors affect cost - and it is possible for
users to alter process features such as catalyst concentrations, hydrogen gas
pressures etc, the overall in use performance costings can present a very wide
range of evaluations.
Nickel and aluminium content is a price factor in the equation for Buyers who
solely concentrate on composition. This may not fully represent catalyst
production costs for varied or developed materials.
Alumina and Aluminium
Alumina compounds resulting from the activation process are those most present
in Raney type nickel according to our work. The preparation determines the
relative amounts and the level of residual aluminium metal.
Customers can be supplied with any specific level of residual alumina species
against agreed limits. Generally it would seem prudent to use low alumina
content catalyst as the alumina compounds could be expected to cause pore
blockage. These manifest themselves as white or grey deposits on catalyst
slurry.
There is an obvious effect on costing or value in respect of alumina content
which can outweigh small increases in prices due to additional processing. The
differences in nickel content shown above amount to about 9%.
Particle size
The average particle diameter range is 10 to 40 microns. Again this aspect of
catalyst requires closer discussion relative to the techniques used for its
determination user and also manufactures experience.
Activity and specificity
The activity of a catalyst is generally dependent upon its particle size. A
high total aluminium material undoubtedly has some high proportion of 'Alumina'
within the pore structure. The activity can be improved in such cases by
supplying finer particle catalyst. Specificity is claimed to be related to pore
characteristics on this issue customers are best placed to determine the
significance either by laboratory or plant trial.
Supernatant pH
Subject to agreement with customers, in view of relevance to other technical factors.
Other technical factors in application
Filterability - the finer the particle size the worse the filter problems. High
'Alumina' content is also known to be an adverse feature due to filter blocking
effect.
Catalyst loss - fine particles create losses and environment problems and ways
of eliminating this issue are under examination.
Pyrophoricity
Modifications are here possible connected to longer term activity maintenance
when catalyst is stored. Work is proceeding in relation to customer demand for
this aspect.
Developed catalyst
All the foregoing factors discussed under Basic Catalyst can be use to vary or
modify Raney type catalyst. A very large number of catalysts can be prepared in
relation to such reasoning.
We would like to discuss the possible implications of this with customers in
confidence.
Modifiers These can be added as specified preferably by the
customer. For example molybdenum added at specific levels as Mo.
Some of the features mentioned above on which investigations are proceeding
will be discussed with customers who show interest.
Chemical Hazard Classification
SAFETY
INFORMATION
UN
NO. 1378 GROUP 2 CLASS 4.2
EMERGENCY ACTION
(UN No. 1378 Class 4.2 Group II, 2 Y CEFIC Trem. Card TEC (R)-42 GO5)
FIRST AID
Drench with water. Remove splashed clothing. In the event of an eye splash the
eye should be immediately thoroughly flushed with water, followed by medical
inspection to ensure that all catalyst particles have been removed.
If an skin or eye irritation persists or arises later, seek medical attention. If accidentally swallowed seek immediate medical attention.
FIRE HAZARD
Fire Spontaneously Combustible Substance but only when
allowed to dry. If allowed to dry in air the nickel is rapidly oxidised
to red head providing a source of ignition to neighbouring combustible material
or flammable vapours. Small amounts of hydrogen may be evolved from the
catalyst in transit and precautions should be taken to avoid ignition. Reacts
with acids vigorously, giving off hydrogen. Reacts violently with oxidising
agents.
Used catalyst also presents an ignition hazard being
mildly pyrophoric on drying in air. It must therefore be treated with the same
care as new material.
Personnel
Irritates eyes and respiratory tract. Contact with skin, eyes and clothing
should be avoided - burns the skin on drying. Brush off clothing with a wet
brush. Always have water available at point of use.
Harmful if taken internally. May cause dermatitis on prolonged skin contact.
The product used correctly under liquids does not have any harmful effects.
Since the rapidly increasing information on the toxicological properties of
chemicals, together with refined analytical techniques are continually
contributing to our overall knowledge of our products we recommend that in
cases of doubt you do not hesitate to contact us.
STORAGE
Store at normal temperature away from oxidising agents, acids, sparks and other
sources of heat or ignition. Material is supplied in metal drums containing
catalyst under an equal weight of water. The drums conform to UN Packaging Type
Code Ref. 1A4. In case of fire use water spray, CO2 extinguisher or sand. Use
spark-proof equipment. NO SMOKING.
Face shield or enclosed goggles, impermeable gloves, plastic or rubber boots
and protective clothing should be worn. Handling operations such as replacement
of water with organic solvent or feed stock should be carried out in a safe
place remote from point of use and away from flammables, oxidising agents,
acids, sources of heat, spark or ignition. Any spillages should be attended to
as below. Strict personal hygiene, no eating, drinking in work area. NO
SMOKING.
SPILLAGE
No smoking! A damaged drum should be placed under water in a larger drum until
experienced personnel are available to handle it. If this is not possible,
remove the drum to a suitably safe spot, eg. clear concrete area away from
flammables, oxidising agents, acids, sources of heat, sparks or ignition. Large
amounts of catalyst spilled should be moistened immediately if dry and then
scooped from the floor and returned into water in a suitable vessel ensuring
that it is not allowed to dry. Residual amounts can be rendered harmless by
treatment with 5% aqueous sodium hypochlorite, if compatible with other spilled
materials present. Nickel is on the 'Grey List' of EEC Directive 76/464 on
Control of Pollution and is subject to UK Control of Pollution Act (Water) and
local requirements.
PACKAGING
Catalysts are supplied in mild steel drums containing 20 kg of catalyst under
water. Alternative packaging will be considered upon request.
SPENT CATALYST
Universal Chemicals will be pleased to discuss the removal and disposal of
spent catalyst, on request.