U.S. patent application number 10/252252 was filed with the patent office on 2003-01-23 for process for the preparation of pulverulent heterogeneous substances.
Invention is credited to Domesle, Rainer, Foerster, Martin, Gutsch, Andreas, Kiessling, Ralph, Stohr, Oliver.
Application Number | 20030017107 10/252252 |
Document ID | / |
Family ID | 27218366 |
Filed Date | 2003-01-23 |
United States Patent
Application |
20030017107 |
Kind Code |
A1 |
Foerster, Martin ; et
al. |
January 23, 2003 |
Process for the preparation of pulverulent heterogeneous
substances
Abstract
A suspension, dispersion or emulsion is introduced into a
burner. An optionally two-stage after-treatment is then carried
out. The resulting powder can be employed as a catalyst.
Inventors: |
Foerster, Martin; (Budingen,
DE) ; Gutsch, Andreas; (Ranstadt, DE) ;
Domesle, Rainer; (Alzenau-Kalberau, DE) ; Kiessling,
Ralph; (Limeshain, DE) ; Stohr, Oliver;
(Fulda, DE) |
Correspondence
Address: |
KALOW & SPRINGUT LLP
488 MADISON AVENUE
19TH FLOOR
NEW YORK
NY
10022
US
|
Family ID: |
27218366 |
Appl. No.: |
10/252252 |
Filed: |
September 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10252252 |
Sep 23, 2002 |
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09824185 |
Apr 3, 2001 |
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09824185 |
Apr 3, 2001 |
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09309504 |
May 11, 1999 |
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6228292 |
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60105392 |
Oct 23, 1998 |
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Current U.S.
Class: |
423/659 ;
502/304; 502/334 |
Current CPC
Class: |
B01J 37/0027 20130101;
B01J 2/00 20130101 |
Class at
Publication: |
423/659 ;
502/334; 502/304 |
International
Class: |
B01J 023/42 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 1998 |
DE |
198 21 144.9 |
Claims
1. A process for the preparation of pulverulent heterogeneous
substances, characterised in that a dispersion, suspension or
emulsion is introduced into a turbulent or laminar burner, this
dispersion, suspension or emulsion is treated there under the
conditions established there, the resulting reaction mixture is
introduced into a downstream flow-through tube, the powder is
treated further there, the powder is subsequently fed, optionally,
to a washer, a separator or a filter, subjected, optionally, to a
further treatment there, and subsequently transported further via
an appropriate device
2. A process and device according to claim 1, characterised in that
the dispersion, suspension or emulsion is present in the high
temperature flow reactor as a gas-borne group of particles.
3. A process and device according to claim 1 and 2, characterised
in that the high temperature flow tube is heated by an exothermic
combustion reaction which takes place in the tube.
4. A process and device according to claim 1 and 2, characterised
in that the high temperature flow tube is heated by feeding in
non-combustible hot gases.
5. A process and device according to claim 1 and 2, characterised
in that the high temperature flow reactor is heated indirectly by
heating up the walls adjacent to the reaction space.
6. A process and device according to claim 1 and 2, characterised
in that the high temperature flow tube is heated by electrical
plasma and/or inductive plasma.
7. A process and device according to claim 1 to 6, characterised in
that a high-energy laser light beam and/or microwave energy is
additionally fed to the high temperature flow reactor.
8. A process and device according to claim 7, characterised in
that, in addition to the dispersion, suspension or emulsion,
non-combustible reactive gases or vapours are fed to the high
temperature flow reactor, the reaction product being a highly
disperse nanostructured solid which adds on to the surface of the
particles of the dispersion or suspension.
9. A process and device according to claim 8, characterised in that
the reaction product forms homogeneous molecular layers on the
particles of the dispersion or suspension, the particles of the
dispersion or suspension thus being coated with a mono- or
multimolecular layer.
10. A process and device according to claim 8, characterised in
that the non-combustible reactive gases or vapours are metal
chlorides and/or organometallic compounds, as well as mixtures of
these compounds.
11. A process and device according to claim 1-10, characterised in
that the temperature in the reaction space is above 1000.degree.
C.
12. A process and device according to claim 1-10, characterised in
that the suspension is fed to the reaction space axially in co- or
countercurrent or radially.
13. A process and device according to claim 1-10, characterised in
that the dispersion or suspension is fed to the reaction space
radially.
14. A pulverulent substance obtainable by a process according to
claim 1-13.
15. The use of a pulverulent substance according to claim 14 as a
catalyst.
16. The use of a pulverulent substance according to claim 14 as an
oxygen store, NO.sub.x store, C.sub.nH.sub.m store for catalysis
and adsorbents.
17. The use of a pulverulent substance according to claim 14 for
the production of ductile ceramic components.
18. The use of a pulverulent substance according to claim 14 for
the production of components with a quantum mechanics activity, in
particular sensors, and photoelectrically active emitters.
19. The use of a pulverulent substance according to claim 14 for
the production of glasses and glass ceramic.
Description
[0001] The invention relates to a process for the preparation of
pulverulent heterogeneous substances.
[0002] It is known to prepare pulverulent heterogeneous substances
from oxides and salts starting from a suspension, dispersion or
emulsion.
[0003] Spray driers (or similar) are usually employed for drying
for suspensions, dispersions or emulsions. This is followed by a
rotary tube for calcining (or similar). The losses of powder by
cleaning and handling, and also during operation of the plant are
or can be considerable, and/or the expenditure on personnel is
high.
[0004] Drying and calcining in batches (for example in vessels in a
muffle furnace) is used as an alternative. However, there is the
risk here of a very wide range of product quality due to diffusion
processes and temperature gradients in the powder.
[0005] There is thus the object of developing a process for the
preparation of pulverulent heterogeneous substances which does not
have these disadvantages.
[0006] The invention provides a process for the preparation of
pulverulent heterogeneous substances, characterized in that a
dispersion, suspension or emulsion is introduced into a turbulent
or laminar burner, this dispersion, suspension or emulsion is
treated there under the conditions established there, the resulting
reaction mixture is introduced into a downstream flow-through tube,
the powder is treated further there, the powder is subsequently
fed, optionally, to a washer, a separator or a filter, subjected,
optionally, to a further treatment there, and subsequently
transported further via an appropriate device.
[0007] In the high temperature flow reactor, the dispersion,
suspension or emulsion can be present as a gas-borne group of
particles.
[0008] The high temperature flow reactor can be heated by feeding
in non-combustible hot gases.
[0009] The high temperature flow reactor can be heated indirectly
by heating up the walls adjacent to the reaction space.
[0010] Heating can be achieved here by electrical plasma and/or
inductive plasma.
[0011] A high-energy laser light beam and/or microwave energy can
additionally be fed to the high temperature flow reactor.
[0012] In addition to the dispersion, suspension or emulsion,
non-combustible reactive gases or vapours can be fed to the high
temperature flow reactor, it being possible for the reaction
product to be a highly disperse nanostructured solid which adds on
to the surface of the particles of the dispersion, emulsion or
suspension.
[0013] The reaction product can form homogeneous molecular layers
on the particles of the dispersion, emulsion or suspension, the
particles of the dispersion, emulsion or suspension being coated
with a mono- or multimolecular layer.
[0014] The non-combustible reactive gases or vapours can be metal
chlorides and/or organometallic compounds, as well as mixtures of
these compounds.
[0015] The temperature in the reaction space can be above
1000.degree. C.
[0016] The suspension, dispersion or emulsion can be fed to the
reaction space axially in co- or countercurrent or radially.
[0017] The dispersion, emulsion or suspension can be fed to the
reaction space radially.
[0018] The dispersion, emulsion or suspension can be a solids
suspension, a solution, powder, pastes, melts or granules with or
without dissolved "salts". The dispersion, emulsion or suspension
is metered into the space in finely divided form by atomizing,
wave-breaking, as a mist or jet.
[0019] The secondary gas mentioned in the FIGURE can be air,
ambient air with oxygen contents of between 0 and 100%, dry or
humid, water vapour, other vapours or gases, nitrogen and the
like.
[0020] The burner can be of a known design with pulsatory
combustion. Such a burner is described in the document DD 114
454.
[0021] A burner of high turbulence can preferably be employed to
improve the transportation of material. In particular, a spinning
burner, possibly with an overlaid pulsation, can be employed.
[0022] The liquid phase of the suspension, dispersion or emulsion
can be water, alcohol, liquid organic hydrocarbons or organic
solvents.
[0023] The components present as the solid in the suspension,
dispersion or emulsion can be, individually or as a mixture:
oxides, nitrides or carbides of aluminium, silicon, cerium,
zirconium, titanium, crystallized-out salts of aluminium, silicon,
cerium, zirconium, lanthanum, barium, metals such as, for example,
nickel, silver, palladium, gold, rhodium, platinum, carbon black,
organic compounds.
[0024] The dissolved or non-dissolved salts can be nitrates,
acetates, carbonates, chlorides of aluminium, cerium, silicon,
zirconium, titanium, lanthanum, barium, platinum, rhodium,
palladium, iridium, potassium, calcium and ammonium and mixtures of
these components.
[0025] A combustible gas, such as, for example, hydrogen and/or
methane, can be used as the fuel.
[0026] The temperature in the burner can be 500 to 2000.degree.
C.
[0027] The temperature after the burner and the reducing or
oxidizing atmosphere in the flow-through tube can be established
via the ratio of oxygen (from the combustion air) to hydrogen and
the flow rates. Moreover, further reactive or inert gases and
vapours can be fed into the tube.
[0028] The dispersion, emulsion or suspension of the solid can be
sprayed or dripped into the flame of the burner.
[0029] The water or the solvent evaporates and the powder formed is
calcined, oxidized or reduced and sintered at high temperatures in
the gas atmosphere present. The residence time of the powder in the
hot gas phase can be varied in the range from 0.01 second up to
minutes by the separating device (cyclone, high temperature
filter). The mass and heat transfer is significantly better than in
a rotary tube or in a muffle furnace.
[0030] With spray calcining, the surfaces to be cleaned are
considerably smaller compared with a spray drier with subsequent
calcining in a rotary tube and the losses of substance are low. Due
to the use of a continuous process, the range of product quality is
narrow. Compared with the rotary tube, the losses during start-up
and shut-down are very low.
[0031] The powder in the waste air filters/cyclone of a rotary tube
has a wide range of product quality and often cannot be used, while
in the process according to the invention the range of product
quality in the waste air filter/cyclone is a very narrow range.
[0032] The in situ treatment of the waste air can have an effect as
a further advantage. The salts are often nitrates, acetates and
ammonium compounds, the decomposition products of which, NO,
NH.sub.3 and CHNO, can be reduced in amount by adjusting the
composition of the hot waste gases or can be treated in a
downstream catalyst without additional heating up.
[0033] The products which can be prepared are heterogeneous
powders/granules:
[0034] 1. Mixed agglomerates and/or mixed aggregates of different
oxides/metals/nitrides/carbides/carbon black.
[0035] 2. Base substances (support material) (possibly in shell
form) impregnated/covered/coated with
oxides/metals/nitrides/carbides.
[0036] 3. Combination of 1. and 2.
[0037] The substances prepared according to the invention can be
employed as a catalyst, for the production of ductile ceramic
components, for the production of components with a quantum
mechanics activity, in particular sensors and photoelectrically
active emitters, and as oxygen stores, NO.sub.x stores,
C.sub.nH.sub.m stores for catalysis and adsorbents.
[0038] The process according to the invention is shown and
explained in more detail in the drawing:
[0039] FIG. 1 shows a burner 1, to which the flow-through tube 2 is
connected. The washer 3, the separator 4, the filter 5 and the fan
6 are connected to the flow-through tube 2.
[0040] In the process according to the invention, a dispersion,
suspension or emulsion, a secondary gas, combustion air and fuel
are introduced into the burner 1. The reaction mixture reacted in
the burner 1 is introduced into the flow-through tube 2. A reducing
or oxidizing gas atmosphere can be established in the flow-through
tube 2. The reacted reaction mixture can be treated in the
flow-through tube 2 such that
[0041] a) the dispersion, suspension or emulsion is dried,
[0042] b) the water of crystallization is driven off,
[0043] c) the powder is calcined, substances such as nitrates,
acetates, carbonates being decomposed to gases,
[0044] d) the powder is oxidized or reduced,
[0045] e) the powder is sintered,
[0046] f) the specific surface area of the powder is decreased.
[0047] After passage through the flow-through tube 2, the powder
can be treated in the washer 3 if a dispersion is to be prepared or
contact with air is to be avoided.
[0048] Alternatively, after leaving the flow-through tube 2, the
powder can be separated off via the separating device 4, for
example for brief treatment at high temperatures.
[0049] In another alternative, the powder can be separated off by
means of the filter 5 for a longer treatment at high
temperatures.
[0050] The waste gas can be discharged by means of the fan 6.
EXAMPLE 1
[0051] A aluminium oxide/water suspension with dissolved platinum
nitrate is introduced into the burner 1. The suspension
comprises
[0052] 400 g/l aluminium oxide
[0053] 10 g/l platinum nitrate
[0054] 800 g/l water.
[0055] Hydrogen is employed as the fuel.
[0056] The burner temperature is 1,200.degree. C., and the
residence time is approx. 1 sec.
[0057] The powder separated off in the cyclone is dry and no longer
contains nitrate ions. The platinum is deposited in a finely
disperse form on the surface of the aluminium oxide.
EXAMPLE 2
[0058] An aqueous suspension which comprises
[0059] 400 g/l aluminium oxide,
[0060] 100 g/l cerium acetate,
[0061] 100 g/l zirconium nitrate and
[0062] 800 g/l water
[0063] is introduced into the burner 1. Natural gas is employed as
the fuel. The burner temperature is 1,000.degree. C. The powder
separated off in the cyclone is dry and contains neither acetate
ions nor nitrate ions. The cerium oxide and the zirconium oxide are
deposited in a finely divided form on the surface of the aluminium
oxide.
EXAMPLE 3
[0064] A moist powder comprising
[0065] 78 wt. % aluminium oxide
[0066] 20 wt. % water
[0067] 2 wt. % platinum nitrate
[0068] is treated with natural gas at a burner temperature of
900.degree. C.
[0069] The powder separated off in the cyclone is dry and contains
no nitrate ions. The platinum is deposited in a finely divided form
on the surface of the aluminium oxide.
* * * * *