Alkaline earth metal dispersion

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

Alkali metal dispersions, or Alkaline earth metal dispersions 1391... 

Alkali metal dispersions, 4.3 Alkaline earth metal dispersion, 4.3 Aluminium, powder Aluminium powder, coated, 4.1 Aluminium powder, pyrophoric Aluminium powder, uncoated, 4.3 Aluminium powder, uncoated, non-pyrophoric, 4.3 Antimony powder, 6.1 Barium dispersions Barium, powder Barium powder, pyrophoric, 4.2... 

Alkali Metal Dispersion Alkaline Earth Metal Dispersion Finely divided alkali or alkaline earth metal, e.g. metallic sodium suspended in a flammable liquid such as toluene, xylene, naphtha, kerosene, etc. Reacts violently with moisture, water or acids, evolving hydrogen, which may be ignited by the heat of reaction. IMO 4324... 

ACTIVATED CARBON 1391 40 ALKALINE EARTH METAL DISPERSIONS... 

Mounted bases NaOH, KOH mounted on silica or alumina Alkali metal and alkaline earth metal dispersed on silica, alumina, carbon, K2CO3 or in oil NR3, NH3, KNHj on alumina LijCOs on silica t-BuOK on xonotolite... 

Diazotization of the aminosulfonic acid and subsequent coupling onto the sodium salt of 2-hydroxy-3-naphthoic acid initially affords the monoazo compound in the form of its soluble sodium salt. Subsequent reaction with chlorides or sulfates of alkaline earth metals or with a manganese salt, frequently in the presence of a dispersion agent, or rosin or its derivatives, at elevated temperature yields the insoluble BONA pigment lake. 

Alkaline-earth metals. Of these metals, Ca, Sr, and Ba, only calcium is produced commercially in appreciable quantities. These three metals are more difficult to produce than the alkali metals since the chlorides of the alkaline-earth metals melt at relatively high temperatures. Furthermore, when these metals are liberated at the cathode, they tend to become colloidally dispersed throughout the molten electrolyte. Accordingly, it is necessary to design the electrolytic cells in such manner to permit the immediate collection of the elemental metal. The type of cell used in the production of calcium serves as a suitable illustration. Molten calcium chloride is placed in a cylindrical vessel around... 

Tsuruya and co-workers (83,84) recently reported that addition of alkaline earth metals (e.g., Ca, Sr, and Ba) to an Ag/SiOi catalyst by a coimpregnation method enhanced the catalytic activity of the partial oxidation of benzyl alcohols into benzaldehydes, with production of only small amounts of byproducts (carbon dioxide, toluene, and benzene). The formation of carbonaceous material was thought to be inhibited by the alkaline earth metals, which also helps to disperse the metallic silver and facilitate oxygen adsorption. This effect causes the formation of an oxygenated silver surface that is generally believed to be responsible for the partial oxidation of benzyl alcohol. 

The redefinition of the comers in Fig. 1(c) separate alkaline earth metals from alkali metals. It can be seen that with this definition the material appears more disperse. It can also be seen that alkali metals are more predominant than alkaline earth metals. There is also small distribution maximum (maximum 1) near to the vertex between the Al+Si% and Ca+Mg% comers. When Al, Na, and Mg are omitted from the definition, this maximum shifts towards the vertex between Si% and Ca% comers [see Fig. 1(d)]. The direction of the shift indicates that the material contains sodium in this region. 

The typical high surface area alumina supports employed have acidic sites that accelerate skeletal isomerization, cracking, oligomerization, and polymerization of olefinic materials, and enhance coke formation. Alkalis or alkaline earth metals assist in the control of the acidity. Also, a-alumina supports that have essentially no acidity can be utilized however, the challenge is to obtain high dispersion of platinum on such very low surface area supports. Therefore, acidity must be eliminated by using suitable modifiers. 

Perovskites of the type LnMO, (Ln = lanthanide and M = transition metal) may offer interesting features as precursors for supported metal catalysts. For example, careful reduction can be carried out in order to produce a finely dispersed transition metal over the sesquioxides Ln,0,. Also, the flexibility in the perovskite composition allows the preparation of compounds of the type LnM ., M 0, (M and M = different transition metals) or Ln., A,MO, (A - for example an alkaline or alkaline earth metal), which show the unique possibility as precursor of producing well dispersed bimetallic catalyst or doped metal catalyst. 

An elaborate technique yielding pyrophoric dispersions of alkaline-earth metals was described by Francois et al.80). Vapor of a continuously boiling inert hydrocarbon is... 

Removal of metal cation from lattices of alkaline-earth is very difficult. Consequently, initiation is extremely slow and the concentration of radical-anions released into the solvent can be very low. Under such conditions radical growth might compete with their dimerization. The reported formation of random co-polymers of styrene and methyl-methacrylate when the mixture of these monomers reacts with dispersions of alkaline-earth metals might be evidence for such a polymerization95. Confirmation of these observations is desirable. 

Alkali Metals The direct use alkali metals and alkaline-earth metals as initiators for anionic polymerization of diene monomers as first reported in 1910 is primarily of historical interest because these are uncontrolled, heterogeneous processes [4]. One of the most significant developments in anionic vinyl polymerization was the discovery reported in 1956 by Stavely and coworkers at Firestone Tire and Rubber Company that polymerization of neat isoprene with lithium dispersion produced high di-l,4-polyisoprene, similar in structure and properties to Hevea natural rubber [47]. This discovery led to development of commercial anionic solution polymerization processes using alkyllithium initiators. 

Alkali metals and alkaline earth metals are often prepared in commerce as dispersions in which the metal is suspended in some liquid, often flammable. 

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