CN101060928A

CN101060928A - Titanium oxide and alumina alkali metal compositions

Info

Publication number: CN101060928A
Application number: CN 200580039912
Authority: CN
Inventors: M·勒芬费尔德; J·L·戴
Original assignee: Michigan State University MSU; SIGNa Chemistry Inc
Current assignee: Michigan State University MSU; SIGNa Chemistry Inc
Priority date: 2004-09-22
Filing date: 2005-09-22
Publication date: 2007-10-24

Abstract

The invention relates to Group 1 metal/silica gel compositions comprising silica gel and an alkali metal or an alkali metal alloy. The compositions of the inventions are described as Stage 0, I, II, and III materials. These materials differ in their preparation and chemical reactivity. Each successive stage may be prepared directly using the methods described below or from an earlier stage material. Stage 0 materials may, for example, be prepared using liquid alloys of Na and K which are rapidly absorbed by silica gel (porous Si02) under isothermal conditions, preferably at or just above room temperature, to form loose black powders that retain much of the reducing ability of the parent metals. When the low melting Group 1 metals are absorbed into the silica gel, a mild exothermic reaction produces Stage I material, loose black powders that are indefinitely stable in dry air. Subsequent heating to 400 DEG C produces Stage II materials, which are also loose black powders. Further heating above 400 DEG C forms Stage III material with release of some Group 1 metal. It is believed that Stage I, II and III materials represent reductions of the silica gel after absorption of the Group 1 metal. Preferred Group 1 metal/silica gel compositions of the invention are those containing sodium, potassium, or sodium-potassium alloys with sodium and sodium- potassium alloys being most preferred. Each stage of the Group 1 metal/silica gel composition of the invention may be used as a reducing agent reacting with a number of reducible organic materials in the same manner known for alkali metals and their alloys.

Description

Titanium oxide and aluminum oxide alkali metal compositions

Technical Field

The present invention relates to porous metal oxide compositions prepared by the interaction of an alkali metal or alloy of these metals with porous titanium oxide or porous alumina. The composition has improved processing characteristics and maintains the reactivity of neutral alkali metals or alloys.

Background

Those alkali metals and alloys of alkali metals in group 1 of the periodic table are very active in their metallic or neutral state. Alkali metals and their alloys are very reactive to air and moisture and may spontaneously ignite when exposed to these agents. To avoid the inherent hazards associated with their activity, neutral metals or alloys must often be stored in a vacuum or in an inert liquid such as oil to avoid it contacting the air, which may cause oxidation or other reactions. For example, sodium metal is often stored in liquid paraffin oil and must be removed before use in chemical reactions to avoid unwanted impurities. This poses serious limitations on its transport and use.

The combination of alkali metals with silicalites such as ZSM-5 has been extensively studied in many laboratories. For example, it has recently been shown that pure silicalite can absorb a maximum of 12 mol% of cesium and considerable amounts of other alkali metals (other than lithium) from the vapor phase. Previous studies on all-silica zeolite encapsulated alkali metals have revealed that this combination can react exothermically with water to produce large quantities of hydrogen. (see, e.g., "heated inorganic electronics", A.S.Ichimura, J.L.Dye, M.A.Camblor and L.A.Villaescusa, J.Am.Chem.Soc., 124, 1170-1171(2002) and "inorganic electronics Formed by Alkali Addition to Pure Silica Zeolites", D.P.Wernette, A.S.Ichimura, S.A.Urbin and J.L.Dye, Chem.Mater.15, 1441-1448, (2003) however, the concentration of sodium absorbed by the zeolite composition is too low to be practical.

Levy et al reported the use of potassium metal dispersed on silica as a reagent in organic synthesis in Angew. Potassium metal is dispersed onto a silica gel (CAS registry No. 7631-86-9: actually colloidal silica, which has no internal surface area) that produces an amorphous material. The reactivity of the material was confirmed with water and benzophenone as shown below. See also Russel et al, Organometallics 2002, 21, 4113, 4128, scheme 3.

Titanium dioxide (TiO) has been reported₂) The sodium is dispersed to readily reduce the zinc chloride, yielding a highly active zinc powder that intercalates into secondary alkyl and benzyl bromides under mild conditions, yielding the corresponding zinc reagent in high yield. (see Heinz Stadtmuller, Bjorn Greve, Klaus Lennick, Abdelatif Chair, and Paul Knochel, "Preparation of SecondaryAlky and Benzylic Zinc Bromides Using Activated Metal deposited on Titanium Dioxide," Synthesis, 1995, 69-72). According to Stadtmuller, a detrimental effect of the residual water content in the carrier was observed. For this reason, solid supports such as barium, tin or alumina and silica cannot be used. Commercial TiO₂Almost anhydrous and constitutes the best carrier for this purpose. Thus, at 150 ℃ to TiO₂(drying at 150 ℃ C. for 2 hours) to sodium (ca. 8g/100g TiO) was added₂) A uniform grey powder resulted after 15 minutes. This powder does not self-ignite, but its exposure to air and moisture results in slow decomposition (2-3 minutes).

Stadtmuller was tested as follows. Adding TiO into the mixture₂(18g, 380mmol) was charged into a 3-necked 100ml flask equipped with an Ar inlet, a glass stopper and a septum cap and heated at 150 ℃ under vacuum (0.1mmHg) for 2 hours. The glass stopper was replaced with a mechanical stirrer, the reaction flask was filled with Ar, and Na (1.50g, 65mmol) was added immediately. Alternatively, Na may be added to the dry TiO at 25 deg.C₂In (1). The reaction mixture was stirred vigorously at 150 ℃ for 15 minutes and cooled to 0 ℃ to give a grey homogeneous powder. Adding dry ZnCl under stirring₂(4.57g, 35.5mmol) in THF (20 mL). After 15 minutes, TiO₂Active Zn on。

The Catalytic Properties of Supported alkali metal Catalysts for hydrogen-deuterium exchange and ethylene hydrogenation were studied by Sterling E.Voltz in The Catalytic Properties of Supported Sodium and Lithium Catalysts J.Phys.chem., 61, 1957, 756, 758. Sodium dispersed on dry alumina does not increase the activity of the alumina for hydrogen-deuterium exchange. However, the exchange activity is greatly increased by sodium hydride-alumina and the hydrogenated catalyst is active even at-195 ℃. Sodium-silica catalysts are much less active than the corresponding sodium-alumina catalysts. Supported sodium and lithium catalysts are active for ethylene hydrogenation even below room temperature; however, in this case, the hydrogen treatment has a relatively small influence on the activity. For both reactions, the supported alkali metal catalysts are much more active than the bulk hydrides of sodium and lithium. The primary function of the support may be to increase the effective area of the alkali metal. The results of this study indicate that the activation mechanism of hydrogen and ethylene on alkali metal hydrides is similar to those previously postulated for alkaline earth metal hydrides. Activation may occur at metal sites at the metal-metal hydride interface. The results obtained with the bulk hydride indicate that hydrogen activation occurs more readily at lithium sites than at sodium sites, and the reverse may be the case for ethylene activation.

The Voltz experiment is as follows. The supported sodium and lithium catalysts were prepared by dispersing the molten metal on powdered alumina or silica which had been vacuum dried at 500 c for about 16 hours. In a typical preparation (sodium-alumina), dry alumina and sodium are placed in a high vacuum reactor equipped with a magnetic stirrer. The transfer of material to the reactor was carried out in a dry box and dry nitrogen. The reactor was slowly heated under vacuum while stirring the solids. When sodium melts, it disperses on the alumina powder. The reactor was heated to about 150 c and held at that temperature (under vacuum and stirring) for at least half an hour. When molten alkali metal is dispersed on the powder, a small amount of gaseous product is emitted in some preparations. In the preparation of the lithium-alumina catalyst, the reactor was heated to about 280 ℃ because the melting point of lithium is higher (186 ℃).

In addition, Alois fur tner and Gunter Seidel are in the High-Surface Sodium' as a Reducing Agent for TiCl₃Synthesis, 1995, 63-68 discloses deposition on inorganic supports such as Al₂O₃、TiO₂And sodium on NaCl ('high surface sodium') for TiCl₃The non-spontaneous combustion reducing agent is cheap and easy to prepare. The low-valent Ti thus obtained is well suited for use in the McMurry coupling reaction, especially of aromatic carbonyl compounds, after a reduction time of only 1 hour. It exhibits a previously unavailable templating effect on the cyclization of dicarbonyl compounds to (macrocyclic) cycloolefins and is suitable for the reduction of N-acyl-2-aminobenzophenone derivatives to 2, 3-disubstituted indoles.

In this connection, Na/Al can be conveniently introduced in two different ways₂O₃Prepared as a homogeneous gray non-pyrophoric powder (method A: mixing/grinding Al at 190 ℃; 180-₂O₃And Na; the method B comprises the following steps: deposition of molten Na on Al suspended in boiling toluene by means of an Ultra turrax stirrer₂O₃Above). For-4 mmol Na/g reagent (10% metal content w/w), the available surface area of alumina was largely exploited without any risk of severe overload.

The assay by Furstner is as follows.

The method A comprises the following steps: sodium sand (10 g; 1-2mm) was added to the pre-dried Al in portions with good mechanical stirring at 190 ℃ under Ar gas and 180 ℃₂O₃(100) The above. Na/Al thus provided₂O₃Is a gray-black, air-sensitive but non-pyrophoric powder that can be stored at room temperature and in Ar for long periods of time without loss of activity. This simple process is less suitable for the preparation of Na/TiO according to Furstner₂And Na/NaCl, because of insufficient mixing.

The method B comprises the following steps: predrying Al in 20min₂O₃(100g) To a strongly stirred suspension in boiling toluene (350mL) was added sodium sand (10 g). Stirring and refluxing was continued for 15min, the mixture was cooled to RT, filtered in Ar, washed with pentane (several times about 300mL) and dried in vacuo. To prepare Na/TiO₂Larger amounts of toluene (800 mL) were required to obtain good agitation. And Id.

Additionally, U.S. patent application Ser. No.10/995327 entitled "SILICA GELCOMPOSITIONS CONTAINING ALKALI METALS AND ALKALIMETAL ALLOYS," filed 24.11.2004, describes SILICA gel compositions prepared by the interaction of an alkali metal or alloy of such metals with SILICA gel, and is incorporated herein by reference.

Thus, there is a need to have alkali metals and their alloys available in a readily processable form without significant loss of metal reactivity. The present invention responds to this need.

Summary of The Invention

The present invention relates to a group 1 metal/porous metal oxide composition comprising the product of mixing a liquid group 1 metal or alloy and a porous metal oxide selected from porous titanium oxide and porous alumina under an inert atmosphere and isothermal conditions near ambient temperature sufficient to absorb the liquid group 1 metal or alloy into the pores of the porous metal oxide. Resulting group 1 metal/porous metal oxide composition and dry O₂And (4) reacting. This material is referred to as a "class 0" material.

The invention also relates to a group 1 metal/porous metal oxide composition comprising the product of mixing a group 1 metal or alloy and a porous metal oxide under exothermic conditions of above ambient temperature sufficient to absorb the group 1 metal or alloy into the pores of the porous metal oxide, the porous metal oxide being selected from porous titanium oxide and porous alumina. The resulting group 1 metal/porous metal oxide composition is free of dry O₂And (4) reacting. Such materials are referred to as "class I" materials.

The invention also relates to a group 1 metal/porous metal oxide composition comprising the product of mixing a liquid group 1 metal or alloy and a porous metal oxide under conditions sufficientto absorb the liquid group 1 metal or alloy into the pores of the porous metal oxide and heating the resulting mixture to a temperature of about 150 ℃ or greater. Resulting group 1 metal/porous metal oxide combinationThe substance does not react with dry O₂And (4) reacting.

The present invention also relates to a process for producing hydrogen gas comprising the step of contacting any one of the group 1 metal/porous metal oxide compositions described herein with water. In addition, the present invention relates to the reduction of organic compounds in the presence of alkali metals, the improvement comprising conducting the reaction in the presence of any of the group 1 metal/porous metal oxide compositions described herein. The reduction reaction may include, for example, dehalogenation and Wurtz reactions.

In addition, the present invention relates to a method of drying an organic solvent comprising the step of contacting the organic solvent with porous alumina for a time sufficient to remove water from the solvent. The contacting step may be carried out batchwise or by means of a column.

Brief Description of Drawings

FIG. 1 shows 2.9mg Na metal and 8.0mg porous Al₂O₃Differential Scanning Calorimetry (DSC) curve of the mixture of (a).

FIG. 2 shows 3.0mg Na metal and 8.2mg porous TiO₂Differential Scanning Calorimetry (DSC) curve of the mixture of (a).

FIG. 3 shows a 14.9mg grade 0 sample-25 wt% Na₂K-TiO₂Differential Scanning Calorimetry (DSC) curve of (a).

FIG. 4 shows a 6.0mg grade I sample-25 wt% Na that has been heated to 150 ℃ overnight₂K-TiO₂Differential Scanning Calorimetry (DSC)curve of (a).

FIG. 5 shows 11.7mg grade 0 sample-25 wt% Na₂K-Al₂O₃By Differential Scanning Calorimetry (DSC) curve of (A), wherein the inset shows Al₂O₃Na absorbed in pores₂The melting of K absorbs heat.

FIG. 6 shows 44.7mg grade I sample-21 wt% Na₂K-Al₂O₃Differential Scanning Calorimetry (DSC) curve of (a).

FIG. 7 shows the use of grade I-25 wt% Na₂K-Al₂O₃Of products of reduction of benzyl chloride¹HNMR spectra, in which the main product is bibenzyl, in productionNo benzyl chloride was detected in the material.

Detailed Description

Group 1 metal: alkali metals and alkali metal alloys

The alkali metals are those of group 1 of the periodic table. The term "group 1 metal" is used herein to describe alkali metals and alloys of alkali metals that can be used in the porous metal oxide compositions of the present invention. These alkali metals include sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Of these alkali metals, sodium and potassium are preferred for the porous metal oxide composition of the present invention, and sodium is particularly preferred.

Alkali metal alloys may also be used in the porous metal oxide compositions of the present invention. The alkali metal alloy is preferably an alloy of two or more alkali metals, such as sodium-potassium (e.g., NaK or Na)₂K)Alloys, which are particularly preferred. Other preferred alkali metal alloys are those containing potassium, cesium and rubidium in each other, especially alloys of these elements with sodium. Alkali metal alloys are within the definition of "group 1 metal" asused in the specification and claims.

In preparing the group 1 metal/porous metal oxide compositions of the present invention, the group 1 metal is typically mixed with a porous metal oxide-porous titanium oxide or porous alumina. The viscosity of the liquid group 1 metal should be at least low enough to be absorbed into the pores of the porous titanium oxide or porous alumina. One way to achieve this is to heat the alkali metal in an inert atmosphere prior to mixing with the porous metal oxide. Alternatively, depending on the grade of material to be prepared, the group 1 metal may be mixed as a solid with the porous metal oxide and the mixture heated to melt the alkali metal.

Another method of introducing the group 1 metal into the porous metal oxide is from the gas phase, as is done with zeolites. (see A.S.Ichimura, J.L.dye, M.A.Camblor and L.A.Villaescusa, J.Am.chem.Soc., 124, 1170-1171(2002) and D.P.Wernette, A.S.Ichimura, S.A.Urbin and J.L.dye, chem.Mater.15, 1441-1448 (2003)). In another method, the group 1 metal can be deposited onto the porous metal oxide from a metal-ammonia solution. (see M.Makesya and K.Grala, Syn.Lett.1997, pp.267-268, "convention priority of 'High Surface Source' in Liquid Ammonia: Use in Acyloin Reaction"). A metal-ammonia solution can be used to avoid agglomeration of the metal when mixed with the porous metal oxide and to prepare a homogeneous mixture of the metal and the porous metal oxide. However, in practice, the metal-aqueous ammonia solution method of mixing the group 1 metal and the porous metal oxide is accompanied by decomposition of a large amount of the metal-aqueous ammonia solution to form an amino compound. However, as preferred in the present invention, simply contacting the liquid group 1 metal with the porous metal oxide avoids the time consuming vapor deposition or metal-ammonia route.

As described below, it is generally preferred for at least the 0-grade material that the group 1 metal have a melting point within about 15 ℃ at room temperature (about 25 ℃). For example, cesium and rubidium have melting points of 28.5 ℃ and 38.5 ℃, respectively. Generally, alloys of two or more alkali metals are and preferably are liquid at or near room temperature. The preferred low melting point alloys are those having various molar ratios of Na to K between 0.5 and 3.0 of sodium and potassium (NaK), more preferably having a 2: 1 molar ratio, i.e., Na₂K. All Na-K alloys with a molar ratio between 0.5 and 2.5 start to melt at a eutectic melting temperature of-12.6 ℃. For a molar ratio of about 0.12 and 3.1, the melting was terminated at 25 ℃. Other binary alloys of alkali metals such as Cs with Rb, K or Na, and Rb with Na or K also melt below or only slightly above room temperature and are therefore suitable for this purpose. Ternary alloys or all four alloys made from three of these four alkali metals will also be sufficiently lowMelting at temperature to form the group 1 metal/porous metal oxide composition of the present invention.

Porous metal oxide

The porous metal oxide powder used in the present invention is porous titanium oxide and porous alumina. Any porous titanium oxide may be used, including TiO, TiO₂、Ti₂O₃And Ti₃O₅. These porous metal oxides can absorb a large amount of absorbed materials in consideration of their porous characteristics. With existing alkali metal adsorbed to titanium oxide or alumina powderIn contrast, the compositions of the present invention absorb alkali metal into the pores of porous titania and porous alumina. Porous titania and porous alumina differ from the more common non-porous forms, such as colloidal titania and colloidal alumina. Porous titanium oxide is available from Sachtleben Chemie and porous alumina is available from Almatis AC.

The porous metal oxide used in the porous metal oxide composition of the present invention preferably has a pore size of 50A to 1,000A. More preferably, the pore size may be 100-300. Even more preferably, the average diameter of the pores of the porous metal oxide is about 150 a.

Although porous metal oxides are free-flowing powders when purchased, they typically contain large amounts of gaseous substances such as water and air. The porous titanium oxide or porous alumina is preferably removed prior to mixing them with the alkali metal or alloy to form the composition of the invention. The porous metal oxide may be degassed using methods known in the art. For example, to remove gaseous species, the porous metal oxide can be heated under vacuum in an evacuated flask, first with a hot air dryer, and then with a torch. This heating achieves a temperature of about 300 ℃. It is also possible, and indeed preferred, to more easily remove the gas and deactivate the active sites by heating the porous metal oxide to 600 c or hotter (900 c) (calcination) in air. The porous metal oxide is typically cooled to room temperature prior to preparing the group 1 metal/porous metal oxide composition of the present invention.

Porous metal oxide compositions comprising alkali metals and alkali metal alloys

The ability to utilize alkali metals or their equivalents in ready forms continues to be a need for the chemical industry and for hydrogen production integration. To meet this need, the present invention is directed to a group 1 metal/porous metal oxide composition comprising a porous metal oxide selected from the group consisting of porous titanium oxide and porous alumina and an alkali metal or alkali metal alloy. The compositions of the invention utilizing titania or porous alumina are described as class 0 and class I materials. These materials differ in their preparation and chemical reactivity. Stage I can be prepared directly from the earlier preparation of stage 0 materials using the methods described below. For example, a grade 0 material can be prepared using a liquid alloy of Na and K that is rapidly absorbed by porous titanium oxide or porous alumina under isothermal conditions, preferably at or just above room temperature, to form a loose black powder that retains most of the reducing power of the parent metal. It is believed that the grade 0 material causes a small amount of the neutral group 1 metal clusters to be absorbed in the porous metal oxide pores. Class 0 materials are pyrophoric, but are less explosive in air than their parent group 1 metals. The grade I material can be prepared by heating the grade 0 material at 150 ℃ overnight. Class I materials are loose black powders that are stable in dry air. Further heating above 200 ℃ results in an exothermic reaction producing additional stages. The class I and higher temperature formed materials are believed to represent the reduction of the porous metal oxide after absorption of the group 1 metal. Preferred group 1 metal/porous metal oxide compositions of the invention are those comprising sodium, potassium or sodium-potassium alloys, with sodium and sodium-potassium alloys being most preferred.

As described below, Na was present at various loadings and mass ratios by Differential Scanning Calorimetry (DSC) tests₂K of a large number of such material samples. Using Na in porous metal oxides melted at-25-0 deg.C₂The heat absorbed at K is used to determine the amount of encapsulated metal that remains as metal in the porous metal oxide. Followed by a broad exothermic peak between 5 ℃ and 450 ℃. No measurable thermal peak was observed when the same sample was cooled and reheated. This indicates that the heat treatment results in the encapsulated metal in the pores reacting with the porous metal oxide to produce new material, although the boundaries are not apparent. This conversion does not significantly alter the hydrogen generating capacity of the material.

The group 1 metal/porous metal oxide composition of the present invention comprises a porous metal oxide with an adsorbed group 1 metal selected from porous titanium oxide and porous alumina. The amount of group 1 metal loading depends on the pore size and pore density of the actual porous metal oxide used. Typically, the group 1 metal may be present in the compositions of the present invention up to about 30 wt%. Preferably, the amount of metal is 25 wt% to 30 wt%. In the class I materials of the present invention, loadings in excess of about 30 wt% result in some free metal remaining in the pores or on the surface of the porous metal oxide.

The grade 0 and grade I metal/porous metal oxide compositions of the present invention react rapidly with water to produce gaseous hydrogen. In the case of class I metal/porous aluminas, the yields are almost quantitative, generally about 90-95%. However, in the case of the grade 0 and I metal/porous titanium oxides, the yield is low. When water was added, about 10% of the added metal did not evolve hydrogen. It is clear that the reaction of metal with porous titanium oxide produces products that do not react with water to produce hydrogen. The group 1 metal/porous metal oxide compositions of the present invention, whose preparation and properties are described below, show promise as a readily transportable and disposable source of clean hydrogen gas and as a powerful reducing agent for the reaction of various organic compounds. Table I below summarizes the preparation and use of the 0 and I grade materials.

TABLE I

Summary of 0 and I

Type of material	Preferred metals/alloys for use	Preparation process
Type of material	Preferred metals/alloys for use	Preparation process	Level
0	Liquid alloy (NaK)₂， NaK，Na₂K, etc.)	Under inert atmosphere or vacuum at room temperature or Porous metal oxide at near room temperature Adding liquid alkali metal alloy. On industrial scale On a mould, preferably by stirring and cooling Slowly adding liquid to porous metal oxide The metal or alloy in the state being produced by dissipation How hot to complete the process	Level
0	Liquid alloy (NaK)₂， NaK，Na₂K, etc.)		From level 0 to I Stage	The liquid alloy (NaK, Na₂k, etc.) The liquid state of the single metal (cesium, rubidium)	Heating under inert atmosphere or vacuum Class 0 material to at least 150 ℃ and up to foot To complete the transformation.
From the solid state 1 st Group metals to I Stage	Sodium, potassium	Under inert atmosphere or vacuum, porous gold Adding solid alkali metal to the metal oxide, and mixing and heating to at least 15At 0 ℃ to bond All metals	From level 0 to I Stage

As noted above, to prepare all of the group 1 metal/porous metal oxide compositions of the present invention, it is preferred to degas or passivate the porous titanium oxide or porous alumina prior to mixing them with the group 1 metal. Generally, in preparing the materials of the present invention, the porous metal oxide is initially heated in air to about 600 ℃ or higher to remove water, degas the porous metal oxide, and reduce defect sites. Other methods of drying, degassing, and/or passivating the porous metal oxide known in the art may also be used.

Class 0 materials

The grade 0 material of the present invention apparently contains a low melting point group 1 metal that is absorbed into the pores of the porous metal oxide without reacting (other than the partial reaction with the porous titanium oxide described above). Thus, the 0-grade material can be considered as nanoscale alkali metal or alkali metal alloy particles that are absorbed within the open pores and channels within the porous metal oxide. The grade 0 material of the present invention is a group 1 metal/porous metal oxide composition comprising mixing a liquid group 1 metal or a liquid group 1 metalalloy under isothermal conditions sufficient to absorb the liquid group 1 metal or liquid group 1 metal alloy into the pores of the porous metal oxideLiquid group 1 metal alloys such as Na₂K and porous titanium oxide or porous alumina. Preferred group 1 metals for the class 0 material include low melting group 1 metals such as cesium or NaK alloys. Class 0 group 1 metal/porous metal oxide compositions of the invention and dry O₂Reactive, unlike class I materials. Since the grade 0 material reacts with dry air, it should be treated in vacuum, in an oxygen-free atmosphere, and preferably in an inert atmosphere, such as nitrogen or an inert gas. Since the class 0 material is spontaneously flammable in air, it can be stored in a closed container such as a screw cap bottle.

To form a grade 0 material, a group 1 liquid metal or alloy is mixed with porous titanium oxide or porous alumina in an inert atmosphere under isothermal conditions, preferably at or slightly above room temperatureAnd a time sufficient to allow the alkali metal or alloy to be absorbed into the silica. Mixing must be carried out in an inert atmosphere such as in a glove box or glove bag. In the formation of the preferred grade 0 material, a liquid group 1 metal such as Na₂K can be poured onto the porous metal oxide bed at room temperature. The agitation is preferably stirring or shaking the mixture to obtain good mixing. The liquid group 1 metal is preferably absorbed into the porous metal oxide without any significant heat of reaction or significant heat release. On a larger scale, it is preferred to add the alkali metal slowly to avoid any exotherm caused by absorption of the alkali metal into the pores of the porous metal oxide.

Depending on the group 1 metal used, the absorption of the liquid group 1 metal to form the 0-grade material preferably occurs within 15 ℃ of room temperature (25 ℃). In a typical process, littleheat evolved so that the sample did not heat up appreciably, but rather was converted to a product that was a free-flowing amorphous black powder in which the individual particles had a light-emitting surface. The mixture is agitated for a time sufficient for the alkali metal or alloy to be absorbed or "drawn" into the pores of the porous titanium oxide or porous alumina. The mixing time is generally dependent on the batch size of the material being prepared and can range from a few minutes to a few hours. Such mixing times are applicable for the preparation of any of the group 1 metal/porous metal oxide compositions of the present invention.

When preparing a grade 0 material, any heat generated or entering the reaction should be controlled or dissipated. Significant temperature increases in the preparation should be avoided. In a preferred embodiment, the grade 0 material is formed at ambient temperature, e.g., near room temperature (25 ℃). Heating well above this temperature generally results in the formation of a class I material. The temperature can be controlled by spreading the porous metal oxide (e.g., on a metal plate), stirring the porous metal oxide, or by cooling the reaction vessel. However, the reaction temperature should be maintained such that the group 1 metal remains in a liquid state so that it can be absorbed by the porous titanium oxide or porous alumina. It should also be noted that when held at room temperature, the grade 0 material may slowly convert to a grade I material over time, but no further conversion to higher grade materials occurs without heating, as described below.

The grade 0 material is a shiny black powder that reacts exothermically with water. The DSC of the grade 0 material prepared with alumina shows the presence of alkali metals in neutral state within the porous metal oxide. This endothermic melting signal was not observed for a grade 0 group 1 metal/porous titanium oxide. Although the exact composition of the grade 0 material is currently unknown, the melting point of the metal in the grade 0 material is lower than the most common group 1 alloys such as Na₂K, thereby indicating that small particles of the group 1 alloy are within the pores of the porous metal oxide.

The class 0 material is the most active member of the group 1 metal/porous metal oxide composition of the present invention. Since the addition of a low melting point alkali metal or alloy to porous titania or porous alumina produces a grade 0 material, with no significant exotherm, the grade 0 material retains most of the reducing power of the alkali metal. Because of their reactivity to air and moisture, they must be handled with care and not be allowed to come into contact with large amounts of air and moisture. Despite these limitations, class 0 materials have utility in strong reduction chromatography applications. The porosity of the packed column of the group 1 metal/porous metal oxide composition of the present invention provides a reducing environment that cannot be achieved with the parent metal or alloy. This allows the grade 0 material to be used to generate hydrogen from water and as a reducing agent that can react with a large amount of reducible organic material in a manner similar to soda ash, as described below.

Class I materials

The class I materials of the present invention are group 1 metal/porous metal oxide compositions which comprise the product of heating a class 0 material or mixing a solid state group 1 metal and porous titania or porous alumina and heating the mixture above the melting point of the metals to absorb the group 1 metal into the pores of the porous metal oxide. The resulting group I metal/porous metal oxide composition is free of dry O₂And (4) reacting. In class I materials, it appears that the alkali metal or alloy has been converted to a form that loses bulk metal properties, such as melting.

The class I materials of the present invention can be formed by mixing a liquid group 1 metal at or just above its melting point with porous titanium oxide or porous alumina under an inert atmosphere such that the group 1 metal is absorbed into the pores of the porous metal oxide. The group 1 metal may also be mixed with the porous metal oxide using one of the alternative methods described above, such as adding the group 1 metal as a vapor. The mixture is then held at or slightly above the melting point of the group 1 metal (i.e., about 70 c to about 150 c) and stirred for a few minutes to a few hours. Generally, higher reaction temperatures convert the material in a shorter time. The reaction to form the class I material is mildly exothermic and on a large scale it is preferred to complete the process by adding the liquid metal or alloy to the porous metal oxide with continuous mixing to remove heat when it is generated. The reaction appears to form an alkali metal-porous metal oxide lattice. The exothermic nature of the reaction causes the class I material to be different from the class 0 material. Heating above the exotherm can convert class I materials to higher class materials, depending on the temperature.

When a low melting group 1 metal is added to a calcined and degassed porous metal oxide in a closed environment such as an Erlenmeyer flask, the system often heats up due to an exothermic reaction between the alkali metal and the porous metal oxide or its defect sites. This results in the formation of a mixture of stages 0 and I. The simplest and most straightforward preparation of a class I material is to heat a class 0 sample overnight at a temperature of 150 ℃ under an inert atmosphere. Other times and temperatures are possible, but care is taken to avoid overheating, which can lead to the formation of higher-grade materials. To ensure a homogeneous product, stirring should be provided during heating.

Class I materials are amorphous black powders that do not react immediately with dry air but react exothermically with water. DSC of the class I material showed little or no group 1 metal remaining within the porous metal oxide. The difference between stage I and stage 0 is that the former can be handled in dry air and even quickly transferred in normal laboratory air without fire or rapid degradation. Class I materials (with and dry O) when kept under a dry oxygen atmosphere for hours to days₂Reacted grade 0 material) does not change and produces the same amount of hydrogen gas as a fresh sample when reacted with liquid water.

Class I materials have many uses in reaction chemistry, as active reducing agents, and for hydrogen production.

Thermal performance

The group 1 metal reacts exothermically with the porous metal oxide compositions of the present invention. 2.9mg solid sodium metal and 8.0 porous alumina (Al) as shown in FIG. 1₂O₃) The Differential Scanning Calorimetry (DSC) curve of the mixture in the DSC panel has a sodium melting endotherm at 98 deg.C (. DELTA.Hequals 89J/g Na) and then multiple exotherms at 280-380 deg.C, (. DELTA.Hequals-235 kJ/mol Na. It is so large that it must represent Na and Al₂O₃A chemical reaction between them. The dotted line is a repeated scan showing no major thermal peak. In fig. 1, the solid line represents the first scan and the dotted line represents the repeat scan.

FIG. 2 shows 8.2mg of porous titanium dioxide (TiO)₂) And 3.0mg of Na metal in a DSC panel. The DSC curve showed a sodium melting endotherm at 98 ℃ (Δ H ═ 107J/g Na) followed by an exotherm at 330 ℃ (Δ H ═ -43.2kJ/mol Na (Δ H ═ -1.88kJ/g Na). Thus, it is believed that the exothermic peaks observed for the various group 1 metal/porous metal oxide compositions in the DSC curves shown in FIGS. 3-6 represent similar reduction reactions.

For example, FIG. 3 shows a 14.9mg grade 0 sample prepared according to the procedure described in example 2Product-25 wt% Na₂K-TiO₂Differential Scanning Calorimetry (DSC) curve of (a). Note that when metals and TiO occur₂There is no endothermic melting and no substantial exothermic heat. FIG. 4 shows a 6.0mg grade I sample-25 wt% Na that has been heated to 150 ℃ overnight₂K-TiO₂As described in example 2. FIG. 5 shows a 11.7mg grade 0 sample-25 wt% Na prepared according to the procedure described in example 1₂K-Al₂O₃Differential Scanning Calorimetry (DSC) curve of (a). Inset shows Al₂O₃Na absorbed in pores₂Melting endotherm of K. A broad exotherm is also evident between 50 and 250 ℃. FIG. 6 shows 44.7mg of a grade I sample, 21 wt% Na, prepared according to the procedure described in example 3₂K-Al₂O₃Differential sweep ofCalorimetry (DSC) curve. Finally, FIG. 7 shows the reduction of benzyl chloride (with grade I, 25 wt% Na) in d-8 hydrofuran (THF) prepared according to the procedure described in example 5₂K-Al₂O₃) Of the product¹H NMR spectrum. The main product is bibenzyl. The aromatic region is on the left and the fat region is on the right. The main peak of bibenzyl was at 2.86 ppm. The small peak to the left is from THF, the small peak at 2.27ppm is from the by-product, toluene.

Reaction chemistry of group 1 metal/porous metal oxide compositions

All of the group 1 metal/porous metal oxide compositions of the present invention react exothermically with water to produce hydrogen. Thus, advantageously, the compositions of the present invention retain the reactivity of the group 1 metal. Thegrade 0 material can be handled simply in dry air, but it reacts slowly with oxygen and rapidly with moisture. In contrast, stage I of the group 1 metal/porous metal oxide composition is not reactive to dry oxygen. As shown in example 7, porous alumina produced recyclable alumina. Thus, porous alumina produces an efficient way to dry the solvent by contacting it with the porous alumina, thereby removing any water without consuming the porous alumina. Such drying may be achieved by a column or by a batch process.

Although the group I group 1 metal/porous metal oxide compositions of the present invention are relatively harmless and do not react strongly, they do have the strong base present and form an alkali metal hydroxide when reacted with water. In contrast to the reaction products of fully soluble silica-gel based materials, the alumina-based materials of the present invention form solid white reaction products that are recyclable only by washing with water and re-calcination at 600 ℃, as shown in example 6. The titania-based materials of the present invention form black solids when reacted with water.

Each stage of the group 1 metal/porous metal oxide composition of the present invention can be used as a reducing agent to react with a wide variety of reducible organic materials in the same known manner as alkali metals and their alloys. For example, the group 1 metal/porous metal oxide composition can be used to reduce aromatic compounds to radical anions, which is common in so-called Birch reduction, often with alkali metal-ammonia solutions. Birch reduction is a common method for reducing aromatic compounds with alkali metals in liquid ammonia. The theory and preparative aspects of Birch reduction are discussed in several reviews. (see G.W.Watt, chem.Rev., 46, 317 (1950); A.J.birch, Quart.Rev. (London), 4, 69 (1950); A.J.birch and H.F.Smith, Quart.Rev. (London), 12, 17 (1958); and C.D.Gutsche and H.H.Peter, org.Syntheses, Coll.Vol.4, 887 (1963)). The group 1 metal/porous metal oxide compositions of the present invention can readily form aromatic radical anions with naphthalene and anthracene in Tetrahydrofuran (THF) solutions. Therefore, they can replace sodium in Birch reduction. Example 4 shows a reduction reaction using the group 1 metal/porous metal oxide composition of the present invention.

Similarly, strong reductions can be performed under controlled conditions, such as Wurtz reduction of halogenated organic compounds such as PCB. The Wurtz reaction is the coupling of two organic groups (R) by treating two moles of organic halide (RX) with two moles of sodium:

2RX+2Na→R-R+2NaX

(see A.Wurtz, Ann.Chim.Phys. [3]44, 275 (1855); Ann.96, 364 (1855); J.L.Wardell, Comp.organometal.chem.1, 52 (1982); W.E.Lindsell, ibid.193; B.J.Wakefield, ibid.7, 45; D.C.Billington, Comp.org.Syn.3, 413-doped 423 (1991)). The group 1 metal/porous metal oxide compositions of the present invention can readily replace sodium in the Wurtz reaction or other such dehalogenation reactions. The compositions of the present invention are also useful for dehalogenating inorganic halides. Example 5 shows a Wurtz reaction using a group 1 metal/porous metal oxide composition of the present invention.

The use of the group 1 metal/porous metal oxide compositions of the present invention allows the alkali metal reactions, such as those described above, to be carried out under safer conditions because the compositions are safer than the corresponding alkali metal or alloy treatments. The use of the composition also generally provides higher yields than corresponding reactions utilizing only the group 1 metal.

Due to class I materials (e.g. class I Na)₂K/porous metal oxide composition) is very easy to prepare and maintains a substantial reduction of the parent group 1 metalAnd thus can be used as a powerful and convenient reducing agent. Small glass columns packed with class I powder are capable of reducing a variety of organic compounds as they dissolve in Tetrahydrofuran (THF) and pass through the column. Alternatively, the batch reaction can be carried out simply by stirring a solution of the organic compound and the stage I material in THF. For example, benzophenone (1) is reduced to a radical anion (carbonyl group) as shown below; the benzyl chloride (2) undergoes Wurtz reduction to form bibenzyl (3).

Numerous other reactions of class I materials are possible. For example, they can reduce naphthalene to radical anions and convert benzyl chloride (2) to bibenzyl (3). Reduction of the representative compounds described above illustrates that the group 1 metal/porous metal oxide compositions of the present invention can reduce aromatic compounds to free radical anions or divalent anions and completely dechlorinate aromatic chlorides. Such materials may damage PCBs by dechlorination. The strong reducing properties of the group 1 metal/porous metal oxide compositions of the present invention also allow chromatographic columns packed with such materials to be used for the reduction of organic and inorganic compounds currently reduced with Na-K or alkali metal-ammonia solutions.

The primary uses of the two-stage reduced porous metal oxide compositions of the present invention are in fuel storage potential and the formation of hydrogen gas required for mobile fuel cells. For example, a bulk reduced porous metal oxide powder charge may be held on a conveyor belt reel within a holding tank. Addition to water will release pure hydrogen and add water vapor. Both stages of reduced porous alumina produce hydrogen gas in quantities close to those produced by the alkali metal used. The hydrogengas can then be used to power the mobile fuel cell. For example, the group 1 metal/porous metal oxide composition feedstock can be held on a conveyor belt reel within a holding tank. Water is then introduced and mixing with the water will release hydrogen which can then be extracted and compressed or pressurized. The compressed hydrogen will be used to fill the mobile fuel cell. The spent powder at this point is now just porous metal oxide, which can be reactivated with new group 1 metals or used for other purposes.

Examples

Example 1: exemplary porous metal oxides. Calcination of porous TiO from Sachtleben Chemie in air at 600 deg.C₂Activated porous aluminas (358 m) of (anatase) (29.5nm diameter pores, or 295. ANG.) and Almatis AC²/g) and then cooled to room temperature. To these powders in a helium-filled glove box liquid Na was added dropwise₂K onto porous oxide in stainless steel disks. The liquid alloy is rapidly absorbed into the porous metal oxide. As long as the total concentration of the metals does not exceed 30 wt%, the white powder becomes dark black in color and the mixture becomes a uniform loose powder. This provided a grade 0 material sample, as shown in fig. 5.

Example 2: one of the obvious features of the group 1 metal/porous metal oxide compositions of the present invention is their ability to generate pure hydrogen when added to water. By adding water to evacuationThe "reducing power" of the group 1 metal/porous metal oxide composition was determined in samples and hydrogen collected using a modified Toeppler pump. The reducing power is defined as the weight percentage of alkali metal or alloy used to generate the same amount of hydrogen. This is confirmed by the collection of hydrogen gas produced by a known mass of material when reacted with degassed water. The hydrogen was collected in a calibrated pipette with a modified toepler pump (mercury fill). This analysis was performed on each sample of reduced porous metal oxide, regardless of the grade of the material. For example, if a 30 wt% sample of NaK in a grade I porous metal oxide produces the same amount of hydrogen as that produced by the amount of NaK alone, the reducing power is 30%. The total amount of alkali metal hydroxide formed is then determined by adding HCl and back-titration with sodium hydroxide. The difference between the total alkali metal percentage and the reducing power resulting from the titration is presumably a measure of the concentration of OH groups and other hydrogen sources present on the porous metal oxide. Alkali metals can react with such groups to release hydrogen during sample preparation. This reaction is presumably the source of detectable amounts of gas formed during mixing of the metal or alloy with the porous metal oxide. Except for addition to porous TiO₂In addition, the amount of hydrogen produced is typically within 90-95% of the amount of hydrogen produced by the metal alone. When Na is used₂K-TiO₂Or Na-TiO₂The hydrogen amount is reduced by an amount equal to about 10% of the metal amount. For example, with 25 wt% Na₂A grade 0 sample of K preparation produced hydrogen equivalent to only 13 wt% metal and another sample with 12 wt% metal produced Na equivalent to only 3 wt% Na₂K, as shown in FIG. 3. Na-TiO preparation with 25 wt% Na₂The class I sample produced hydrogen equivalent to only 16 wt% metal. In contrast, Na with 30% metal₂K-Al₂O₃The class I sample produced hydrogen equivalent to 27 wt% metal. Even at 2 hours of exposure to dry air, the hydrogen yield was equivalent to 23 wt% metal, indicating partial reaction with air, but only mild reactivity.

Example 3: the preparation of the grade I material can be carried out by continuouslyheating the grade 0 material to 150 c or by using higher melting alkali metals such as sodium and potassium. 14.0g of degassed and calcined porous alumina was weighed into a Parr stainless steel reactor equipped with a Teflon gasket seal, along with 6.0g of Na metal. The combination of porous metal oxide and Na was heated while rotating the reactor upside down at 60rpm, first to 105 ℃ for 1 hour, then at 155 ℃ overnight. The powder was loose, black and free flowing. Conversion of grade 0 Na was also carried out₂K-Al₂O₃、Na₂K-TiO₂And Na-TiO₂Similar process to the class I material. For example, a DSC of 21 wt% material is shown in figure 6.

Example 4. All alkali metal-porous metal oxide powders, whether 0 or I, are capable of reducing naphthalene and anthracene to the corresponding radical anion. Reduction was observed by forming a strong green or blue color of the solution, respectively. These radical anions are stable enough to last in solution for several hours. Several reaction apparatuses may be used to perform such a reaction, such as a batch reaction, or a column loaded with the reduced material of the present invention. The reaction with anthracene can be as shown below.

Example 5: one of the early reactions of alkali metals with organic compounds was the Wurtz reaction, in which dehalogenation of chlorocarbon compounds results in coupling to form new carbon-carbon bonds. However, when used in the form of bulk alkali metal and pure chlorocarbon compounds, the reaction can be dangerously explosive. As shown below, by using grade I Na₂K-TiO₂And Na of grade I₂K-Al₂O₃(～25wt％Na₂K) This coupling reaction was carried out by reducing benzyl chloride dissolved in THF. The former was performed by passing through a small column made of a Pasteur pipette and filled with reducing material, and the latter was performed in a batch reaction.¹The only product of HNMR detection was bibenzyl (see fig. 7).

Example 6. To detect recycled class I Na₂K-Al₂O₃About 7.5g of this material was allowed to react with water, resulting in the formation of a large amount of white residue. It was washed 5 times (centrifuged each time) and dried. The dried powder was then calcined at 600 ℃ and fed into a helium-filled glove box. The recovered sample weighed 5.0g and was mixed dropwise with 1.86g of Na₂K are mixed to form a loose black powder with a nominal metal concentration of 27.3% by weight. Na constituted by such a reconstitution₂K-Al₂O₃The hydrogen collection of (2) produced hydrogen equivalent to 20.8 wt% metal. Although the recovery process did not provide 100% of the starting material, these results indicate that stage I Na can be recovered by washing and calcination₂K-Al₂O₃. Thus, the same Al can be reused simply by washing, heat-treating and reintroducing the alkali metal₂O₃And (3) sampling.

Claims

1. A group 1 metal/porous metal oxide composition comprising the product of:

mixing a liquid group 1 metal and a porous metal oxide in an inert atmosphere and under isothermal conditions sufficient to absorb the liquid group 1 metal into the pores of the porous metal oxide, the porous metal oxide being selected fromPorous titanium oxide and porous alumina, wherein the resulting group 1 metal/porous metal oxide composition is reacted with dry O₂And (4)reacting.

2. The group 1 metal/porous metal oxide composition of claim 1, wherein the porous metal oxide has pores with diameters of 50 to 1,000 a.

3. The group 1 metal/porous metal oxide composition of claim 1, wherein the group 1 metal is selected from the group consisting of sodium, potassium, rubidium, cesium and alloys of two or more group 1 metals.

4. The group 1 metal/porous metal oxide composition of claim 1, wherein the mixing of the liquid group 1 metal and the porous metal oxide selected from porous titanium oxide and porous alumina occurs at ambient temperature.

5. A group 1 metal/porous metal oxide composition comprising the product of:

mixing a liquid group 1 metal and a porous metal oxide under exothermic conditions sufficient to absorb the liquid group 1 metal or liquid group 1 metal alloy into the pores of the porous metal oxide, the porous metal oxide selected from the group consisting of porous titanium oxide and porous alumina, wherein the resulting group 1 metal/porous metal oxide composition is free of dry O₂And (4) reacting.

6. The group 1 metal/porous metal oxide composition of claim 5 wherein the pores of the porous metal oxide have an average pore diameter of about 50 to 1,000 a diameter.

7. The group 1 metal/porous metal oxide composition of claim 5, wherein the group 1 metal is selected from the group consisting of sodium, potassium, rubidium, cesium and alloys of two or more group 1 metals.

8. The group 1 metal/porous metal oxide composition of claim 5, wherein the group 1 metal is present in an amount up to 30 wt%.

9. A group 1 metal/porous metal oxide composition comprising the product of:

mixing a liquid group 1 metal and a porous metal oxide under exothermic conditions sufficient to absorb the liquid group 1 metal into the pores of the porous metal oxide and heating the resulting mixture to a temperature of at least 150 ℃, the porous metal oxide being selected from the group consisting of porous titanium oxide and porous alumina, wherein the resulting group 1 metal/porous metal oxide composition is free of dry O₂And (4) reacting.

10. The group 1 metal/porous metal oxide composition of claim 9, wherein the pores of the porous metal oxide have an average size of about 50-1,000 a diameter.

11. The group 1 metal/porous metal oxide composition of claim 9, wherein the group 1 metal is selected from the group consisting of sodium, potassium, rubidium, cesium and alloys of two or more group 1 metals.

12. The group 1 metal/porous metal oxide composition of claim 9, wherein the group 1 metal is present in an amount up to about 30 wt%.

13. A method of preparing a group 1 metal/porous metal oxide composition grade 0 comprising the step of contacting a liquid group 1 metal with a porous metal oxide selected from porous titanium oxide and porous alumina under isothermal conditions and in an inert atmosphere or vacuum to adsorb the group 1 metal into the pores of the porous metal oxide.

14. The process for preparing a group 1 metal/porous metal oxide composition of claim 13, wherein the liquid group 1 metal and the porous metal oxide selected from porous titanium oxide and porous alumina are contacted at ambient temperature.

15. A method of preparing a class I group 1 metal/porous metal oxide composition comprising the steps of:

heating the group 0 group 1 metal/porous metal oxide composition of claim 13 to 150 ℃ for a time and under conditions to convert the group 0 group 1 metal/porous metal oxide composition to a group I group 1 metal/porous metal oxide composition.

16. A method of preparing a class I group 1 metal/porous metal oxide composition comprising the steps of:

mixing a liquid group 1 metal and a porous metal oxide selected from porous titanium oxide and porous alumina under exothermic conditions sufficient to absorb the liquid group 1 metal or liquid group 1 metal alloy into the pores of the porous metal oxide.

17. A method for producing hydrogen gas comprising the step of contacting the group 1 metal/porous metal oxide composition of claim 1 with water.

18. A method for producing hydrogen gas comprising the step of contacting the group 1 metal/porous metal oxide composition of claim 5 with water.

19. A method for producing hydrogen gas comprising the step of contacting the group 1 metal/porous metal oxide composition of claim 9 with water.

20. In a reduction reaction of an organic compound in thepresence of an alkali metal, the improvement comprising conducting the reaction in the presence of the group 1 metal/porous metal oxide composition of claim 1.

21. In a reduction reaction of an organic compound in the presence of an alkali metal, the improvement comprising conducting the reaction in the presence of the group 1 metal/porous metal oxide composition of claim 5.

22. In a reduction reaction of an organic compound in the presence of an alkali metal, the improvement comprising conducting the reaction in the presence of the group 1 metal/porous metal oxide composition of claim 9.

23. The reduction of an organic compound in the presence of an alkali metal according to claim 20, wherein the reduction is a dehalogenation reaction or a Wurtz reaction.

24. The reduction of an organic compound in the presence of an alkali metal according to claim 21, wherein the reduction is a dehalogenation reaction or a Wurtz reaction.

25. The reduction of an organic compound in the presence of an alkali metal according to claim 22, wherein the reduction is a dehalogenation reaction or a Wurtz reaction.

26. A method of drying an organic solvent comprising the steps of:

an organic solvent is contacted with the porous alumina for a time sufficient to remove water from the solvent.

27. The method of drying an organic solvent of claim 26, wherein the contacting step is performed by a batch process orby a column.