U.S. patent application number 09/824185 was filed with the patent office on 2002-04-25 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 | 20020047221 09/824185 |
Document ID | / |
Family ID | 27218366 |
Filed Date | 2002-04-25 |
United States Patent
Application |
20020047221 |
Kind Code |
A1 |
Foerster, Martin ; et
al. |
April 25, 2002 |
Process for the preparation of pulverulent heterogeneous
substances
Abstract
A suspension, dispersion or emulsion is introduced into a
burner. A 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: |
SMITH GAMBRELL & RUSSELL, L.L.P.
Suite 800
1850 M Street, N.W.
Washington
DC
20036
US
|
Family ID: |
27218366 |
Appl. No.: |
09/824185 |
Filed: |
April 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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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: |
264/5 ; 264/10;
264/7 |
Current CPC
Class: |
B01J 37/0027 20130101;
B01J 2/00 20130101 |
Class at
Publication: |
264/5 ; 264/7;
264/10 |
International
Class: |
B29B 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 1998 |
DE |
198 21 144.9 |
Claims
We claim:
1. A process for the preparation of a pulverulent heterogeneous
substance, comprising introducing a dispersion, suspension or
emulsion into a turbulent or laminar burner, heating the
dispersion, suspension or emulsion under reaction conditions
established in said burner to obtain a reaction mixture powder,
introducing said reaction mixture powder into a downstream flow
through tube, treating said powder with a gas, optionally feeding
said powder to a washer, a separator or a filter.
2. The process according to claim 1, wherein said dispersion,
suspension or emulsion is present in the high temperature flow
through tubes reactor as a gas-borne group of particles.
3. A process according to claim 1, further comprising heating the
flow through tube by an exothermic combustion reaction which takes
place in the tube.
4. The process according to claim 1, further comprising heating the
flow through the tube by feeding in non-combustible hot gases.
5. The process according to claim 1, further comprising heating the
flow through tube indirectly by heating up flow through tube walls
adjacent a reaction space of said tube.
6. The process according to claim 1, further comprising heating the
flow through tube by electrical plasma and/or inductive plasma.
7. The process according to claim 1, further comprising subjecting
the flow through tube to a high-energy laser light beam and/or
microwave energy.
8. The process according to claim 7, further comprising, in
addition to the dispersion, suspension or emulsion in the form of
particles, feeding a non-combustible reactive gas or vapour to the
flow through tube to produce a reaction product which is a highly
dispersed nanostructured solid which adds on to the surface of the
particles of the dispersion, suspension or emulsion.
9. The process according to claim 8, wherein the reaction product
formed thereby is a homogeneous molecular layer on the particles of
the dispersion, suspension, or emulsion, the particles of the
dispersion, suspension or emulsion being thereby coated with a
mono- or multimolecular layer.
10. The process according to claim 8, wherein the non-combustible
reactive gas or vapour is at least one of a metal chloride or
organometallic compound.
11. The process according to claim 1, wherein the temperature of
the reaction is above 1000.degree. C.
12. The process according to claim 1 wherein the reaction
temperature is 500 to 2000.degree. C.
13. The process according to claim 1, wherein the dispersion,
suspension or emulsion is fed to the burner axially in co- or
countercurrent or radially.
14. The process according to claim 13, wherein the dispersion,
suspension or emulsion is fed to the reaction space radially.
15. The process according to claim 1 wherein the powder is in a hot
gas phase for at least 0.01 seconds.
16. A pulverulent substance obtainable by the process according to
claim 1.
17. The use of a pulverulent substance according to claim 16 as a
catalyst.
18. The use of a pulverulent substance according to claim 16 as an
oxygen store, NO.sub.x store, C.sub.nH.sub.m, store for catalysis
and adsorbents.
19. The use of a pulverulent substance according to claim 16 for
the production of ductile ceramic components.
20. The use of a pulverulent substance according to claim 16 for
the production of components with a quantum mechanics activity, in
particular sensors, and photoelectrically active emitters.
21. The use of a pulverulent substance according to claim 16 for
the production of glasses and glass ceramic.
Description
REFERENCE TO A RELATED APPLICATION
[0001] This application is a continuation-in-part of our copending
provisional application 60/105,392 filed Oct. 23, 1998 which is
relied on and incorporated herein by reference.
INTRODUCTION AND BACKGROUND
[0002] The present invention relates to a process for the
preparation of pulverulent heterogeneous substances.
[0003] It is known to prepare pulverulent heterogeneous substances
from oxides and salts starting from a suspension, dispersion or
emulsion.
[0004] Spray driers or similar apparatus are usually employed for
the drying of suspensions, dispersions or emulsions. This is
followed by a rotary tube or equivalent apparatus for calcining.
With such prior known methods the losses of powder by cleaning and
handling, and also during operation of the plant are or can be
considerable; also the labor costs can be high.
[0005] Drying and calcining in batches (for example in vessels in a
muffle furnace) can be used as an alternative. However, there is
the risk with such apparatus of a very wide range of product
quality due to diffusion processes and temperature gradients in the
powder.
[0006] It is therefore an object of the present invention to
prepare pulverulent heterogeneous substances and to overcome the
disadvantages of prior known methods.
SUMMARY OF THE INVENTION
[0007] The above and other objects can be achieved according to the
present invention by introducing a dispersion, suspension or
emulsion into a turbulent or laminar burner. This dispersion,
suspension or emulsion is then treated there under the conditions
established therein to produce a reaction mixture. The resulting
reaction mixture is then introduced into a downstream flow-through
tube, where the powder is further treated. The powder is
subsequently fed, optionally, to a washer, a separator or a filter,
and, optionally, subjected to a further treatment there.
Subsequently, the pulverulent product can be transported further
via any appropriate device.
BRIEF DESCRIPTION OF DRAWING
[0008] The present invention will be further understood with
reference to the accompanying drawing which is a schematic flow
diagram of the process of the invention.
DETAILED DESCRIPTION OF INVENTION
[0009] The present invention will now be described in further
detail with reference to the accompanying drawing. In carrying out
the process of this invention, in the high temperature flow
reactor, the dispersion, suspension or emulsion can be present as a
gas-borne group of particles.
[0010] The high temperature flow reactor can be heated by feeding
in non-combustible hot gases.
[0011] The high temperature flow reactor can be heated indirectly
by heating up the walls of the reactor adjacent to the reaction
space where the reaction takes place.
[0012] Heating can be achieved in this embodiment by electrical
plasma and/or inductive plasma.
[0013] A high-energy laser light beam and/or microwave energy can
additionally be used as an energy source for the high temperature
flow reactor.
[0014] 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 dispersed nanostructured solid which adds on
to the surface of the particles of the dispersion, emulsion or
suspension.
[0015] 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.
[0016] The non-combustible reactive gases or vapours can be metal
chlorides and/or organometallic compounds, as well as mixtures of
these compounds.
[0017] The temperature in the reaction space can be above
1000.degree. C.
[0018] The suspension, dispersion or emulsion can be fed to the
reaction space axially in co- or countercurrent or radially.
[0019] The dispersion, emulsion or suspension can be fed to the
reaction space radially.
[0020] 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.
[0021] 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.
[0022] The burner can be of a known design with pulsatory
combustion. Such a burner is described in the document DD 114 454
which is relied on and incorporated by reference herein.
[0023] 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.
[0024] The liquid phase of the suspension, dispersion or emulsion
can be water, alcohol, liquid organic hydrocarbons or organic
solvents.
[0025] The components present as the solid in the suspension,
dispersion or emulsion can be, individually or as a mixture:
oxides, nitrides or carbides of aluminum, silicon, cerium,
zirconium, titanium, crystallized-out salts of aluminum, silicon,
cerium, zirconium, lanthanum, barium, metals such as, for example,
nickel, silver, palladium, gold, rhodium, platinum, as well as
carbon black and organic compounds.
[0026] The dissolved or non-dissolved salts can be nitrates,
acetates, carbonates, chlorides of aluminum, cerium, silicon,
zirconium, titanium, lanthanum, barium, platinum, rhodium,
palladium, iridium, potassium, calcium and ammonium and mixtures of
these components.
[0027] A combustible gas, such as, for example, hydrogen and/or
methane, can be used as the fuel.
[0028] The temperature in the burner can be 500 to 2000.degree.
C.
[0029] 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.
[0030] The dispersion, emulsion or suspension of the solid can be
sprayed or dripped into the flame of the burner.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] The products which can be prepared are heterogeneous
powders/granules:
[0036] 1. Mixed agglomerates and/or mixed aggregates of different
oxides/metals/nitrides/carbides/carbon black.
[0037] 2. Base substances (support material) (possibly in shell
form) impregnated/covered/coated with
oxides/metals/nitrides/carbides.
[0038] 3. Combination of 1. and 2.
[0039] 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.
[0040] The process according to the invention is shown and
explained in more detail in the drawing:
[0041] 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.
[0042] 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
[0043] a) the dispersion, suspension or emulsion is dried,
[0044] b) the water of crystallization is driven off,
[0045] c) the powder is calcined, substances such as nitrates,
acetates, carbonates being decomposed to gases,
[0046] d) the powder is oxidized or reduced,
[0047] e) the powder is sintered,
[0048] f) the specific surface area of the powder is decreased.
[0049] 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
if contact with air is to be avoided.
[0050] 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.
[0051] In another alternative, the powder can be separated off by
means of the filter 5 for a longer treatment at high
temperatures.
[0052] The waste gas can be discharged by means of the fan 6.
[0053] The following examples are illustrative of the present
invention.
EXAMPLE 1
[0054] An aluminum oxide/water suspension with dissolved platinum
nitrate is introduced into the burner 1. The suspension
comprises
1 400 g/l aluminum oxide 10 g/l platinum nitrate 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
dispersed form on the surface of the aluminum oxide.
EXAMPLE 2
[0058] An aqueous suspension which comprises
2 400 g/l aluminum oxide, 100 g/l cerium acetate, 100 g/l zirconium
nitrate and 800 g/l water
[0059] 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 aluminum
oxide.
EXAMPLE 3
[0060] A moist powder comprising
3 78 wt. % aluminum oxide 20 wt. % water 2 wt. % platinum nitrate
is treated with natural gas at a burner temperature of 900.degree.
C.
[0061] 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 aluminum oxide.
[0062] By following the procedure set forth in examples 1-3 similar
results can be obtain with the oxides, nitrides or carbides of
silicon, cerium, zirconium, lanthanum, barium, as well as the
corresponding compounds with metals such as, for example, nickel,
silver, palladium, gold, rhodium, and platinum. In similar manner,
carbon black and organic compounds can also be used in the method
of this invention.
[0063] Further variations and modifications of the foregoing will
be apparent to those skilled in the art and are intended to be
encompassed by the claims appended hereto.
[0064] German priority application 198 21 144.9 is relied on and
incorporated herein by reference.
* * * * *