Non self-igniting solid

Details Non self-igniting solid Non self-igniting solid

1999-07-13

2002-03-19

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S156000, C526S129000, C526S348000, C526S943000, C502S104000, C502S107000

Reexamination Certificate

active

06359086

ABSTRACT:

The present invention relates to a solid which does not self-igniting, comprising:
a) at least one support component,
b) at least one chemical compound which per se is self-igniting,
c) at least one inert liquid and
d) further components if desired.
The present invention additionally relates to processes for preparing a solid which does not self-ignite and to the use of such a solid for catalytic or stoichiometric carbon-carbon bond linking or for hydrogenation.
It has long been known, and is frequently desirable, to fix reactive, chemical compounds chemically or physically on support materials and thereby to enhance their suitability for particular chemical processes. Examples of important industrial-scale chemical processes are polymerization, hydrogenation or the drying of fluids, for example liquids or gases.
In polymerization processes, for example, especially in the production of polyolefins, use is made of solid, support-bound Ziegler, Phillips or metallocene catalyst systems. A common feature of these catalysts is that they include generally pyrophoric constituents, with the result that the catalysts may spontaneously ignite, especially under oxidizing conditions, for example on the ingress of air.
The self-ignitability of the solids, demonstrated by way of example in polyolefin catalysts, hinders or even prevents totally their use in large-scale industrial processes, since for safe working it necessitates special protective measures, which are often expensive and technically complex.
In addition, the classification of these solids, especially the polyolefin catalysts, as self-igniting substances greatly limits their transportation; for example, rapid despatch by air freight is not permitted.
WO 95/07939, WO 87/03889, WO 93/23439 and WO 94/28034 disclose the preparation of support-bound metallocene catalysts in suspension, subsequent removal of the solvent and drying of the solid to give a free-flowing catalyst. WO 93/23439 specifies drying as an essential step to obtain catalysts having advantageous properites. The dried catalysts of the prior art have the disadvantage that they are self-igniting.
Wetting of the dry solids, especially the polymerization catalysts, leads in general to unwanted properties in the catalysts, such as reduced polymerization activity, or formation of lumps which are difficult to meter.
It is an object of the present invention, therefore, to provide solids, especially flowable polyolefin catalysts, which are not self-igniting and which are virtually unimpaired in their other relevant properties.
We have found that this object is achieved by a solid which does not self-ignite, comprising:
a) at least one support component,
b) at least one chemical compound which per se is self-igniting,
c) at least one inert liquid and
d) further components if desired.
This solid is referred to below as “novel solid”. We have also found a process for preparing a novel solid where the components a) to d) are mixed and then some of component c) is removed. We have also found a process for preparing a novel solid where components a) to d) are mixed, then virtually all of component c) is removed, and then a component c) is added to the dry solid again in an amount such that this solid does not self-ignite. We have also found that the novel solid can be used for catalytic or stoichiometric carbon-carbon bond linkage or for hydrogenation or drying of liquids.
There is broad scope for variation in the support component a). All organic or inorganic solids are suitable in general, especially those that are porous. Examples of particularly suitable inorganic support components a) are particulate oxides or salts. Examples of particularly suitable organic support components a) are particulate polymers.
Examples of particulate organic support material a) are polyolefins such as polyethylene, polypropylene, poly-1-butene and polymethyl-1-pentene and copolymers with the monomers on which these polymers are based, and also polyesters, polyamides, polyvinyl chloride, polyacrylates, polymethacrylates and polystyrene. However, preference is given to particulate inorganic support materials a), such as porous oxides, for example SiO
2
, Al
2
O
3
, MgO, ZrO
2
, TiO
2
, B
2
O
3
, CaO and ZnO. Metal halides, such as MgCl
2
, are other suitable supports. The support materials a) preferably have a particle diameter of from 1 to 300 &mgr;m, in particular from 30 to 70 &mgr;m. Examples of particularly preferred supports are silica gels, preferably those of the formula SiO
2
.aAl
2
O
3
, in which a is a number in the range from 0 to 2, preferably from 0 to 0.5; ie. aluminosilicates or silicon dioxide. Products of this kind are obtainable commercially, for example Silica Gel 332 from Grace.
There is likewise broad scope for variations in the component b) which per se is self-igniting and is defined by its property of self-ignition. Self-ignition is defined by the UN Recommendations Section 14.3 and EEC Directive 92/69, A 13, as described at length in the Examples. Examples of compounds which fall within this definition are organometallic compounds, metal hydrides or organometal hydrides, principally those of groups 1, 2, 3, 4, 5, 6, 12, 123, 13, 14 and 15 of the Periodic Table of the Elements (group numbering in accordance with the 1985 IUPAC Recommendation). Examples of particularly suitable components b) are lithium organyls, aluminum organyls and boron organyls. Preference is given to open-chain or cyclic alumoxane compounds which according to U.S. Pat. No. 4,794,096 can be obtained by reacting aluminum trialkyls with water. They are composed of from 5 to 30 structural units &Brketopenst;O Al(R
1
)&Brketclosest; connected in chain form or cyclic form, in which each R
1
is a C
1
-C
4
-alkyl, preferably methyl or ethyl. The alumoxane compounds can also be present in a mixture with other metal alkyls, preferably with aluminum alkyls.
Also used are aluminum organyls of the formula Al(R′)
3
, in which R′ is hydrogen, C
1
-C
10
-alkyl, preferably C
1
-C
4
-alkyl, especially methyl, ethyl or butyl. R′ can also be arylalkyl or alkylaryl each of 1 to 10 carbons in the alkyl and 6 to 20 carbons in the aryl. Also suitable are aluminum alkyls Al(R′)
3
in which R′ can be fluorine, chlorine, bromine or iodine, with the proviso that at least one radical R′ is a C-organic radical or hydrogen. Particularly preferred compounds are trimethylaluminum, triethylaluminum, triisobutylaluminum, diisobutylaluminum hydride and diethylaluminum chloride.
The components b) can be employed alone or as mixtures in the novel solid, the proportions of the mixture not being critical.
The components b) are generally applied by impregnating the support solid with the liquid and/or dissolved components b). Solvents suitable for this purpose are in general those which constitute component c). Component c) is an inert liquid, in other words a chemical compound which is liquid under standard conditions and which under standard conditions does not undergo, or undergoes only very slowly, chemical reaction with component b), with partial or complete chemical conversion of component b), in general decomposition, or with its own partial or complete chemical conversion. Partial chemical conversion is generally not the case until more than about 10 mol-%, preferably 3 mol-% and, in particular, 1 mol-% of the pure substance c) employed has been converted.
Highly suitable compounds for use as component c) are inert organic compounds such as aliphatic, isocyclic or aromatic hydrocarbon carbons. Examples are n-hexane, n-heptane, n-octane, isododecane, cyclohexane, toluene, ethylbenzene, 1-hexene, 1-pentene, 1-heptene and 1-octene, preferably n-heptane. It is of course also possible to use mixtures or isomers of these compounds as component c), especially those which are offered commercially, such as EC 180 from Shell or Isopar from Exxon.
The content of the liquid c) in the novel solid comprising a) to c) and optionally d) is such that c) is just no longer self-igniting but is still flowable, ie. co

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