U.S. patent application number 09/861598 was filed with the patent office on 2001-11-01 for magnesium ethoxide having a high coarse particle content, process for its preparation and its use.
This patent application is currently assigned to DEGUSSA-HULS AKTIENGESSELLSCHAFT. Invention is credited to Frings, Albert-Johannes, Horn, Michael, Jenkner, Peter, Monkiewicz, Jaroslaw, Rauleder, Hartwig, Schork, Reinhold, Standke, Burkhard.
Application Number | 20010036900 09/861598 |
Document ID | / |
Family ID | 7885700 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010036900 |
Kind Code |
A1 |
Schork, Reinhold ; et
al. |
November 1, 2001 |
Magnesium ethoxide having a high coarse particle content, process
for its preparation and its use
Abstract
Particulate magnesium ethoxide having a high coarse particle
content can be obtained in a simple and economical manner by the
present invention, which provides a process for preparing
particulate magnesium ethoxide having a coarse grain content, and
includes reacting metallic, optionally activated, magnesium with
liquid ethanol under pressure at a temperature above 78.degree. C.
The present invention also relates to particulate magnesium
ethoxide having a coarse grain content, which contains: <40% by
weight of a screening fraction .ltoreq.500 .mu.m and .gtoreq.60% by
weight of a screening fraction >500 .mu.m.
Inventors: |
Schork, Reinhold;
(Rheinfelden, DE) ; Standke, Burkhard; (Loerrach,
DE) ; Rauleder, Hartwig; (Rheinfelden, DE) ;
Frings, Albert-Johannes; (Rheinfelden, DE) ; Horn,
Michael; (Rheinfelden, DE) ; Jenkner, Peter;
(Rheinfelden, DE) ; Monkiewicz, Jaroslaw;
(Rheinfelden, DE) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
DEGUSSA-HULS
AKTIENGESSELLSCHAFT
Frankfurt
DE
|
Family ID: |
7885700 |
Appl. No.: |
09/861598 |
Filed: |
May 22, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09861598 |
May 22, 2001 |
|
|
|
09427926 |
Oct 27, 1999 |
|
|
|
Current U.S.
Class: |
502/171 |
Current CPC
Class: |
C07C 31/30 20130101;
C07C 29/70 20130101; C07C 29/70 20130101; C07C 31/30 20130101 |
Class at
Publication: |
502/171 |
International
Class: |
B01J 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 1998 |
DE |
198 49 353.3 |
Claims
1. A particulate magnesium ethoxide having a coarse grain content
comprising: <40% by weight of a screening fraction .ltoreq.500
.mu.m and .gtoreq.60% by weight of a screening fraction >500
.mu.m.
2. The particulate magnesium ethoxide as claimed in claim 1,
comprising <10% by weight of a screening fraction <315
.mu.m.
3. The particulate magnesium ethoxide as claimed in claim 1,
comprising from 0.01 to 5% by weight of a screening fraction
<315 .mu.m.
4. The particulate magnesium ethoxide as claimed in claim 1,
comprising .gtoreq.80% by weight of a screening fraction <500
.mu.m.
5. The particulate magnesium ethoxide as claimed in claim 1,
comprising >40% by weight of a screening fraction >800
.mu.m.
6. The particulate magnesium ethoxide as claimed in claim 1, which
is produced by a process comprising reacting metallic, optionally
activated, magnesium with liquid ethanol under pressure at a
temperature above 78.degree. C.
7. A process for preparing particulate magnesium ethoxide having a
coarse grain content, comprising: reacting metallic, optionally
activated, magnesium with liquid ethanol under pressure at a
temperature above 78.degree. C.
8. The process as claimed in claim 7, wherein the liquid ethanol
and metallic magnesium are contacted with one another in a reaction
space, heated under pressure to a temperature above 78.degree. C.,
wherein the liquid ethanol is available as a reaction partner, and
wherein hydrogen is formed and ejected from the reaction space.
9. The process as claimed in claim 7, wherein the reaction
temperature is from >78 to 200.degree. C. and the pressure in
the reaction space is above 1 bar absolute.
10. The process as claimed in claim 7, wherein the reaction
pressure is above 1 bar absolute.
11. The process as claimed in claim 7, wherein the metallic
magnesium has a particle size of 20 to 5000 .mu.m.
12. The process as claimed in claim 7, further comprising raising
the temperature to above 90.degree. C. at the start of the
reaction.
13. The process as claimed in claim 7, wherein hydrogen is formed
and wherein the peak of hydrogen formation proceeds at a
temperature below 90.degree. C., and wherein the hydrogen is
removed from the reaction space.
14. The process as claimed in claim 12, further comprising
continuing the reaction at a temperature above 90.degree. C.
15. A precursor for a Ziegler-Natta catalyst, comprising the
magnesium ethoxide as claimed in claim 1.
16. A ceramic precursor, comprising the magnesium ethoxide as
claimed in claim 1.
17. A precursor for book preservation media, comprising the
magnesium ethoxide as claimed in claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a particulate magnesium
ethoxide having a coarse particle content, to a process for its
preparation and to its use.
[0003] 2. Discussion of the Background
[0004] Processes for preparing magnesium ethoxide have been known
for a considerable time. One industrial preparation route is the
direct synthesis from metallic magnesium and ethanol. This is
described, for example, by H. D. Lutz in Zeitschrift for
anorganische und allgemeine Chemie, Volume 356, 1968, pages 132 ff.
A catalyst is typically required to start the reaction and,
generally, iodine is used as the catalyst. Magnesium ethoxide
prepared in this manner disadvantageously includes traces of the
starter catalyst, which can have adverse consequences, for example,
when the resultant magnesium ethoxide is used as a catalyst
precursor for Ziegler catalysts or for book preservation. If
catalysts are not used, however, the reaction between ethanol and
magnesium is not reliably initiated; and uncontrollable initiation
behavior inheres great risk in industrial processes.
[0005] In the known processes for preparing magnesium ethoxide,
long reaction times are also economically prohibitive. For example,
for the complete reaction of ethanol magnesium to occur, reaction
times of more than 24 hours are required. If the reaction is
terminated prematurely, incompletely reacted metallic magnesium
remains in the mixture together with magnesium ethoxide; and
separation cannot be reasonably carried out with standard
equipment. In addition, the metallic magnesium impairs the
properties of magnesium ethoxide.
[0006] Finally, the synthesis of magnesium ethoxide by known
processes always produces magnesium ethoxide having considerable
amounts of undesirable, undersized grains. This fine grain or dust
content likewise impairs the properties of the product. This
product content can be removed only with a great deal of expense
during the preparation of magnesium ethoxide, for example by
sieving or classifying, and discarding. It is desirable, therefore,
to provide a process which enables the production of magnesium
ethoxide in a particularly economical manner.
SUMMARY OF THE INVENTION
[0007] Accordingly, one object of the present invention is to
provide a magnesium ethoxide having a high coarse particle content
in a simple and economic manner.
[0008] Another object of the present invention is to provide a
process for making a magnesium ethoxide having a high coarse
particle content that is simple and economically feasible.
[0009] Surprisingly, it has now been found that particulate
magnesium ethoxide having a high coarse particle content can be
obtained in a simple and economical manner by the present
invention, the first embodiment of which relates to a process for
preparing particulate magnesium ethoxide having a coarse grain
content, including reacting metallic, optionally activated,
magnesium with liquid ethanol under pressure at a temperature above
78.degree. C.
[0010] Another embodiment of the present invention relates to a
particulate magnesium ethoxide having a coarse grain content, which
contains:
[0011] <40% by weight of a screening fraction .ltoreq.500 .mu.m
and
[0012] .gtoreq.60% by weight of a screening fraction >500
.mu.m.
[0013] The process according to the present invention can be
reliably started in a simple and economical manner and without a
catalyst contaminating the product. In addition, the present
process can completely avoid the unwanted residue of incompletely
reacted metallic magnesium. The reaction times of the present
process are generally markedly less than 24 hours, which inheres a
particularly economical mode of operation. Furthermore, a product
having a comparatively low content of unwanted undersize grain or
dust content is obtained.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description of the preferred embodiments.
[0015] Preferably, in the process according to the present
invention, metallic, optionally activated, magnesium is brought
into contact with anhydrous ethanol in the liquid phase under
pressure at a temperature above the boiling temperature of ethanol
at atmospheric pressure (78.degree. C.), the mixture is reacted to
completion and the product is isolated.
[0016] Preferably, in the reaction according to the invention,
liquid ethanol and solid metallic magnesium are brought into
contact and heated under pressure to a temperature above 78.degree.
C. in such a manner that liquid ethanol is available as a reaction
partner, and the hydrogen that is formed is ejected from the
reaction space.
[0017] Preferably, to carry out the reaction according to the
invention, dried ethanol is used in excess, so that ethanol can
simultaneously serve as solvent. The magnesium ethoxide arising in
the reaction according to the invention is then preferably isolated
by filtration or by concentrating the product mixture at a
temperature in the range from 0.degree. to 180.degree. C. under
reduced pressure. More preferably, the isolation temperature ranges
from 5 .degree. to 150.degree. C., even more particularly
preferably 10.degree. to 125.degree. C., and most preferably
15.degree. to 100.degree. C. Prior to product isolation, the
resulting product mixture can be preferably cooled to a temperature
of 20.degree. to 78.degree. C. More preferably, the cooling
temperature ranges from 25.degree. to 75.degree. C., even more
particularly preferably 30.degree. to 70.degree. C., and most
preferably 35.degree. to 65.degree. C.
[0018] Preferably, both the reaction according to the invention and
the isolation of the magnesium ethoxide according to the invention
are carried out under a protective gas. A CO.sub.2-free protective
gas which has been dried in a manner known per se is preferably
used, for example nitrogen or argon. Nitrogen, dried and
CO.sub.2-free, is most preferred.
[0019] Most preferably, the present invention relates to a process
for preparing particulate magnesium ethoxide having a coarse grain
content, wherein metallic, optionally activated magnesium is
reacted with ethanol in the liquid phase and subsequently the
magnesium ethoxide is isolated, which includes carrying out the
reaction under pressure at a temperature above 78.degree. C.
[0020] Preferably, in the process according to the invention, the
reaction temperature is set to a value of from >78 to
200.degree. C., particularly preferably from 80 to 130.degree. C.,
very particularly preferably from 100 to 130.degree. C., and the
pressure in the reaction space is set to a value above 1 bar
absolute, particularly preferably to a value of from 2 to 6 bar
absolute.
[0021] The metallic magnesium used in the process according to the
invention preferably has a particle size of from 20 to 5000 .mu.m.
Preferably, it is used as pure magnesium metal. However, before the
reaction, it can also be activated, for example by etching.
[0022] To start the reaction, a catalyst may be preferably added to
the reaction mixture. The catalyst is preferably made of an
inorganic or organic halogen compound, preferably a mercury halide,
an inorganic or organic acid, such as HCl or acetic acid, or an
alkyl orthoformate, such as tetraethyl orthoformate (TEOF).
[0023] Preferably, in the process according to the invention, the
reaction is started by raising the temperature briefly to above
78.degree. C., and more preferably >90.degree. C. Preferably, in
the further course of the reaction, the peak of hydrogen
development proceeds at a temperature below 90.degree. C.; the
resulting hydrogen is conducted away from the reaction space; and
the remaining reaction proceeds at a temperature above 90.degree.
C., likewise with ejection of the hydrogen formed. Preferably, the
reaction has generally proceeded quantitatively after 16 hours, so
that in an advantageous manner, virtually no magnesium metal
residues remain in the product mixture. The product is generally
isolated from the product mixture in the manner described
above.
[0024] Particulate magnesium ethoxide prepared according to the
invention advantageously has a high content of coarse grains. The
grain content is generally determined under dry protective gas by
screening analysis according to the usual methods.
[0025] The present invention therefore also relates to a
particulate magnesium ethoxide having a coarse grain content by
weight, containing <40% of a screening fraction .ltoreq.500
.mu.m (mesh width) and .gtoreq.60% by weight of a screening
fraction >500 .mu.m.
[0026] Preferably, magnesium ethoxide according to the invention
contains .gtoreq.80% by weight of a screening fraction >500
.mu.m (mesh width).
[0027] Most preferably in the magnesium ethoxide according to the
invention, the content of a screening fraction >800 .mu.m (mesh
width) is more than 40% by weight, based on the total amount.
[0028] In addition, magnesium ethoxide according to the invention
preferably contains less than 10% by weight, particularly
preferably from 0.01 to 5% by weight, of a screening fraction
<315 .mu.m (mesh width). That is to say that particulate
magnesium ethoxide according to the invention has a high content of
coarse grain, which is very desirable and particularly economical;
and, in a particularly surprising and advantageous manner, only a
comparatively low content of undersize grain, and the content of
fine dust virtually (and desirably) approaching zero.
[0029] Preferably, the process according to the invention is
carried out as follows: nitrogen, anhydrous ethanol and particulate
metallic magnesium are introduced under a dry protective gas
atmosphere into a heatable stainless steel pressure reactor
equipped with an adjustable overpressure valve, and the mixture is
heated to a temperature above 78.degree. C. A pressure above
ambient pressure can develop in the sealed reactor owing to the
vapor pressure of the ethanol used and the development of hydrogen
according to reaction 1.
Reaction 1
Mg+2C.sub.2H.sub.5OH.fwdarw.Mg(OC.sub.2H.sub.5).sub.2+H.sub.2
[0030] If this exceeds the limit set at the overpressure valve, the
valve can open and hydrogen and ethanol vapor may escape. The
expanded gas mixture is generally passed through a cooler, with
ethanol condensing, while hydrogen is conducted away in a gaseous
state. The condensed ethanol can be recirculated to the reactor via
a metering pump which can overcome the overpressure prevailing in
the reactor. This reaction procedure has the particular advantage
that it is not necessary to use a condensation system suitable for
overpressure. If an overpressure safe condensation system is
available, the overpressure control valve can likewise be mounted
at the top of the condensation system in such a manner that the
expanded gas downstream of the pressure control valve principally
contains hydrogen. The condensation system reflux, ethanol, is
generally recirculated to the reactor, so that recycling of ethanol
with overcoming of pressure can be avoided.
[0031] Preferably, the reaction can also be started at atmospheric
pressure, e.g. with the use of catalysts known from the literature,
such as halogens, halogen compounds, acids, mercury compounds or
alkyl orthoformates, and can then be continued with an increase in
pressure. This generally has the advantage that pressure peaks
caused by the initially very vigorous reaction at elevated
temperature (>78.degree. C.) can be made less extreme. An
unmanageable pressure increase in the reactor represents a
considerable hazard potential.
[0032] A further preferred method for the reaction procedure
includes beginning the reaction in the absence of catalyst at
atmospheric pressure and the boiling temperature of ethanol (78
.degree. C.) and increasing the pressure and temperature in the
plant as the reaction progresses. Pressure peaks can likewise be
avoided in this manner. If problems with respect to initiating the
reaction should exist, the reaction can be started by a brief
increase in the temperature and pressure. Immediately after the
start of the reaction, uncontrolled hydrogen development can be
checked by decreasing the pressure and temperature in the reactor
by expansion via the pressure control valve.
[0033] The product is preferably isolated in the process according
to the invention in the above-mentioned manner.
[0034] In addition, the process according to the invention has the
advantage that when particulate magnesium having a mean particle
size >200 .mu.m, preferably .gtoreq.800 .mu.m, is used, the
reaction time is less than 24 hours, no metallic magnesium remains
in the product and significantly fewer undersize grain are produced
than when the product is prepared at atmospheric pressure by
conventional processes.
[0035] Preferably, the particulate magnesium ethoxide according to
the invention having a coarse grain content, on account of its
advantageous properties, is particularly suitable as a precursor
for Ziegler-Natta catalysts, as a precursor for ceramics and a
precursor for book preservation media.
EXAMPLES
[0036] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples, which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
Reaction Apparatus
[0037] 1-1 stainless-steel autoclave with close-clearance agitator,
pressure measuring device (aneroid manometer), temperature
measuring device (Pt 100 sensor, temperature control via
thermostat, liquid metering pump (diaphragm pump Prominent
Gamma/4-/, adjustable overpressure valve, condensation system
(intensive glass cooler), gas meter (drum gas meter TG3, Ritter)
and protective gas blanketing (nitrogen).
Drying Apparatus
[0038] Protective gas (nitrogen)blanketed laboratory rotary
evaporator (2-1 glass evaporator flask) with vacuum facility.
Reaction Procedure
[0039] 24.3 g of particulate metallic magnesium (d50 >800 .mu.m,
purity: >99%) are introduced together with 356 g of ethanol
under a protective gas curtain into a stainless-steel autoclave.
After sealing the apparatus, the overpressure valve is set to the
desired internal reactor pressure and the mixture is brought to
reaction temperature. On reaching the preset temperature and the
preset pressure, hydrogen and ethanol vapor escape via the pressure
control valve into the condensation system. Ethanol condensed out
is pumped back into the reactor via the diaphragm metering pump at
the rate at which condensate is formed in the cooler. The resulting
hydrogen is removed from the reaction apparatus via the drum gas
meter. The volumetric flow rate of hydrogen is measured. If
hydrogen development can no longer be observed, the reaction is
terminated by depressurizing and cooling the reactor. The
suspension (magnesium ethoxide in ethanol) is transferred to the
2-1 flask of the rotary evaporator and dried there in the course of
2.5 hours at 100.degree. C. and under reduced pressure (to 1 mbar).
The product is then subjected to a particle size analysis
(screening analysis). In addition, the content of incompletely
reacted metallic magnesium is determined indirectly from the amount
of hydrogen formed on adding aqueous hydrochloric acid to the
product.
[0040] 1. (NP6994) Preparation of magnesium ethoxide from ethanol
and magnesium at 110.degree. C. and a pressure of 3 bar
[0041] The procedure as described under "reaction procedure" is
followed. The temperature of the heating medium (silicone oil) of
the thermostat is 170.degree. C. At a pressure of 3 bar in the
reactor, the temperature in the reactor is 110.degree. C.
Approximately 5 minutes after reaching the reaction temperature,
the maximum hydrogen development of approximately 30 1/h is
measured. The reaction is complete after approximately 6 hours; no
more hydrogen development occurs. The product is dried and analyzed
as described above.
1 Screening Analysis >800 .mu.m 55.7% by weight 500-800 .mu.m
36.4% by weight 315-500 .mu.m 7.1% by weight 200-315 .mu.m 0.6% by
weight 100-200 .mu.m 0% by weight <100 .mu.m 0.1% by weight
Metallic Magnesium <0.02% by weight
[0042] 2. (NP6694) Preparation of magnesium ethoxide from ethanol
and magnesium at 120.degree. C. and a pressure of 4 bar
[0043] The procedure as described under "reaction procedure" is
followed. The temperature of the heating medium (silicone oil) of
the thermostat is 170.degree. C. At a pressure of 4 bar in the
reactor, the temperature in the reactor is 120.degree. C.
Approximately 5 minutes after reaching the reaction temperature,
the maximum hydrogen development of approximately 35 1/h is
measured. The reaction is complete after approximately 3.5 hours;
no more hydrogen development occurs. The product is dried and
analyzed as described above.
2 Screening Analysis >800 .mu.m 46.2% by weight 500-800 .mu.m
36.4% by weight 315-500 .mu.m 13.1% by weight 200-315 .mu.m 3.3% by
weight 100-200 .mu.m 0.8% by weight <100 .mu.m 0.1% by weight
Metallic Magnesium <0.02% by weight
[0044] 3. Preparation of magnesium ethoxide from ethanol and
magnesium at 78 .degree. C. and atmospheric pressure (1 bar,
comparative example, NP6894)
[0045] The procedure as described under "reaction procedure" is
followed, but with the difference that the magnesium turnings used
are washed with 0.1 N aqueous HCl to remove the oxide layer and
dried under protective gas at 100.degree. C. to increase the
reactivity; the reaction is not reliably initiated without this
step. The temperature of the heating medium (silicone oil) of the
thermostat is 120.degree. C. At a pressure of 1 bar in the reactor
(atmospheric pressure), the temperature in the reactor is
78.degree. C. Approximately 5 minutes after reaching the reaction
temperature, the maximum hydrogen development of approximately 6
1/h is measured. After approximately 7 hours, a sample is taken
from the reactor. The reaction product still contains considerable
amounts of incompletely reacted magnesium which is visible to the
eye. Hydrogen development is not complete until after a reaction
time of more than 24 hours, and the reactor is cooled. The product
is dried and analyzed as described above.
3 Screening Analysis >800 .mu.m 5.9% by weight 500-800 .mu.m
39.5% by weight 315-500 .mu.m 42.9% by weight 200-315 .mu.m 8.6% by
weight 100-200 .mu.m 2.6% by weight <100 .mu.m 0.5% by weight
Metallic Magnesium <0.02% by weight
[0046] The particle size distribution shows a marked increase of
unwanted undersized grain (content of particles <315 .mu.m is
>11%).
[0047] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
[0048] This application is based on German patent application DE
19849353.3, filed Oct. 27, 1998, the entire contents of which are
hereby incorporated by reference.
* * * * *