MXPA01001236A - Dispersion and stabilization of reactive atoms on the surface of metal oxides - Google Patents

Abstract

Particulate metal oxide compositions having reactive atoms stabilized on particulate surfaces and methods for reacting the compositions with saturated and unsaturated species are provided. The preferred particulate metal oxides of the compositions are nanocrystalline MgO and CaO with an average crystallite size of up to about 20 nm. The preferred reactive atoms of the compositions are atoms of the halogens and Group I metals. In one embodiment, chlorine atoms are stabilized on the surface of nanocrystalline MgO thus forming a composition which is capable of halogenating compounds, both saturated and unsaturated, in the absence of UV light and elevated reaction temperatures.

Description

DISPERSION AND STABILIZATION OF REACTIVE ATOMS IN THE SURFACE OF METALLIC OXIDES BACKGROUND OF THE INVENTION Field of the Invention The present invention is broadly related to compositions of metal oxide particles of halogen atoms and Group IA metals. Preferred metal oxide particles include nanocrystalline MgO and CaO, with average crystallite sizes up to 20 nm. In one embodiment, the potassium atoms are stabilized on the surface of the nanocrystalline MgO at a charge of 10-40% by weight of potassium based on the total weight of the K / MgO composition, thereby forming useful superbases for the isomerization and alkylation of unsaturated species. In another embodiment, the chlorine atoms are stabilized on the surface of nanocrystalline MgO thus forming a composition that is capable of halogenating compounds in the absence of UV light and elevated temperatures, as well as providing a source of chlorine that does not use water for bleaching purposes. . REF. NO.126808 Description of the Prior Art It is known that the nanocrystalline metal oxides having an average crystallite size of up to 20 nm possess surface reactivities and adsorption powers which are considerably higher than the typically available samples of metal oxides. It is believed that the increased surface reactivities of these nanocrystalline metal oxides is due to the morphological characteristics of the small crystallites, such as the high population of surface reactive sites at the edges and at the corners, and at sites with ionic vacancies. The small sizes and unusual shapes of the crystallites provide large ion ratios of the edges / corners with respect to the total surface ions. The presence of these edge / corner sites and other defects of reactive sites (such as vacancies) allow these materials to possess surprisingly high surface concentrations of reactive surface ions. For example, an edge or corner of the anion O2- is saturated in a coordinated manner and is "looking" for Lewis acids to help stabilize and delocalize its negative charge. Conversely, an Mg2 + ion at an edge or corner site is "looking" for Lewis bases to stabilize and delocalize its positive charge. Therefore, these coordinately unsaturated O2"and Mg2 + readily accept incoming reagents with Lewis base or Lewis acid characteristics.

Solid superbases (as used herein, bases that are strong enough to extract a proton from toluene) are generally created when metal oxides are treated with alkali metals. These materials are capable of acting as catalysts for the isomerization of alkenes at room temperature. However, they are only capable of isomerization reactions at elevated temperatures (ie, 150 ° C or higher), and even then only for certain types of alkylations. These disadvantages result from the inability to achieve sufficiently high loads of the alkali metal in the form of ions and electrons of dissociated metal on the surfaces of the metal oxides. That is, in order to create superbases with enhanced alkylation capabilities, high alkali metal charges are required and hereafter can not be obtained.

Halogens exist as diatomic molecules unless they contact an oxidizable compound. To halogenate a molecule, it is first necessary to dissociate the diatomic molecule into halogen atoms that are reactive. For example, if Cl2 is added to methane, no reaction will occur because diatomic chlorine is very stable and non-reactive. However, if UV light is added, or if the reaction is carried out at a temperature of about 300 ° C, the Cl2 will dissociate into reactive chlorine atoms, thereby chlorinating the methane and reforming Cl2 if there is an availability inadequate for the reaction. In the prior art there are no methods by which the halogens can be stabilized in the form of reactive atoms in the absence of the use of UV light or at high reaction temperatures.

The present invention overcomes these problems by providing compositions comprising metal oxide particles having reactive atoms stabilized on their surface, as well as methods for the isomerization, alkylation, and halogenation of unsaturated species (e.g., alkenes) as well as the halogenation of alkanes using such compositions.

In more detail, the compositions of the invention comprise metal oxide particles having portions of oxygen ions on their surfaces, as well as methods for isomerization, alkylation, and halogenation of unsaturated species (e.g., alkenes) as well as the halogenation of alkanes using such compositions.

In greater detail, the compositions of the invention comprise metal oxide particles having portions of oxygen ions on their surfaces with interacting reactive atoms or chemisorbed with those surface oxygen ions. Preferably, the metal oxide particles are taken from the group consisting of Mg, Ca, Ti, Zr, Fe, V, Mn, Fe, Ni, Cu, Al, Zn, or mixtures thereof, Mgo and CaO being particularly preferred. While the metal oxide particles can be used to form the compositions, the preferred particles are nanoparticles prepared by the airgel techniques of Utamapanya et al., Chem. Ma ter. 3: 175-181 (191). The metal oxide particles should advantageously have an average crystal size of up to 20 nm, more preferably from about 3 to 9 nm, and more preferably about 4 nm. Additionally, the particles should have a BET surface area of multiple points of at least 15 m2 / g, preferably at least about 200 m2 / g and more preferably at least about 500 m2 / g.

Preferably, the reactive atoms of the compositions are selected from the group consisting of halogen atoms and Group IA metals. When a metal atom of Group IA is stabilized, the atomic charge in the metal oxide should be from 5% to 40% by weight, preferably from 10% to 15% by weight, and more preferably 12% by weight. % by weight, based on the weight of the atomically charged metal oxide taken as 100%. The atomic charge on the metal oxide can also be expressed as a concentration of atoms per unit surface area of the metal oxide, ie, at least about 2 atoms per nm 2 of metal oxide surface area, preferably 3-8 atoms per nm 2. of metal oxide surface area, and more preferably of 4-5 atoms per nm2. The preferred metal of group IA used in the compositions of the invention is potassium.

The metal-atom oxide adducts of the invention exhibit certain characteristics of the classical oxygen-atom bond, but probably can not be properly characterized in any way. Instead, the adducts exhibit a type of weak weak link or chemisorption between the reactive O2"sites of the metal oxide and the stabilized atoms.According to the conditions of ambient pressure, in a closed system the adducts reach an equilibrium condition where some of the atoms attached to the surface migrate from the oxide and the atoms in the gas phase are reattached to the sites on the oxide surface.In the case of adducts containing chlorine, for example, small amounts of Cl2 gas they can be observed in a closed system which indicates that the chlorine atoms migrate from the surface of the oxide and dimerize, while the Cl2 molecules in the environment react to split and join the chlorine atoms to open reactive sites, to establish a equilibrium condition.

The compositions are formed by heating a quantity of metal oxide particles at a temperature of at least about 200 ° C, preferably at least about 300 ° C, and more preferably at a level of about 450 to about 500 ° C. By heating the metal oxide particles at these temperatures the water in the particles is removed such that the final compositions of the invention have a surface hydroxyl concentration of less than about 5 hydroxyl groups per square nanometer of metal oxide surface area. The particles are allowed to cool to ' room temperature. Subsequently, the particles contact a source of reactive atoms, for example, a diatomic molecule which dissociates into reactive atoms under the appropriate reaction conditions. The reactive atoms interact with the surface oxygen ions of the metal oxide, thus stabilizing the atoms on the surface of the oxide. As used hereafter, the terms "stabilized" and "stable" mean that, when the metal oxide-atom adducts are heated to a temperature of about 100 ° C, less than 10% of the total loss in Adduct weight is attributable to the desorption of reactive atoms.

The metal oxide-atom adducts of the invention can also be formed as a tablet for situations where they are not practical. particles with nanoscale sizes. These pellets are formed by the agglomeration of finely divided metal oxide-atom adducts by any suitable process, for example by pressing at a pressure of about 5000 psi and more preferably at a 2000 psi. While these pressures are typically applied to the metal oxide-atom adducts by an automatic or hydraulic pressure, the pellets can be formed by any pressure applying means. In addition, a binder or filler can be mixed with the metal-atom oxide adducts, and / or the pellets can be formed by manually pressing the mixture: Agglomeration or agglomeration as used hereinafter, includes all known processes for this purpose such as the techniques of centrifugation or joint pressure of the metal oxide-atom particles.

The halogenated metal oxide compositions of the present invention can be used to halogenate unsaturated species (such as alkenes) as well as saturated species (such as alkanes). This is achieved by contacting the composition with a target compound at a very wide temperature range of about -80 to about 240 ° C, but preferably the contact temperature is less than 25 ° C, more preferably less than 0 ° C, and much more preferably less than -23 ° C. If the metal oxide-stabilized atom used composition is Cl / CP-CaO or Cl / AP-MgO, the contacting step is carried out at a temperature lower than -42 ° C and preferably lower than -78 ° C. Advantageously, the present invention provides compositions and methods for halogenating (and particularly for chlorinating) saturated compounds in the absence of UV light and without high reaction temperature characteristics of the prior art. In addition, the chlorinated metal oxide compositions of the invention can be used as a source of chlorine for bleaching purposes without requiring the use of water.

The superbasic compositions of the present invention are useful for the isomerization and alkylation of alkenes and other unsaturated species. The alkenes are isomerized by contacting the superbasic compositions with alkene, preferably under the pressure of an alkene at about 80-120 psi. Superbasic compositions and methods for the isomerization of alkenes are particularly useful for the conversion of DMB (2,3-dimethyl-l-butene) to tetramethylethylene, and 1-pentene to trans- or cis-2-pentene.

The alkenes or other species are alkylated by contacting one of these superbasic compositions with a first alkene (such as propylene) under an alkene pressure of 80-120 psi. The resng product subsequently contacts a second alkene (such as ethylene), preferably at a second alkene pressure of about 80-120 psi. In this way, the second alkene is rented by the first alkene.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates the experimental equipment used in the preparation of a K / MgO adduct of the invention in a Schlenk tube; Figure 2 is a graph illustrating the degree of isomerization of DMB by K / AP-MgO compared to the degree of isomerization of DMB by K / CP-MgO; Figure 3 is a graph illustrating the effect of potassium loading on samples of AP-MgO and CP-MgO in the degree of isomerization of 1-pentene; Figure 4 is a graph comparing the degree of alkylation of propylene by means of toluene with the degree of alkylation of ethylene by means of toluene using 15% by weight of post-step charge on AP-MgO based on the total weight of sample of AP-MgO; Figure 5 is a graph illustrating the alkylation of ethylene by means of propylene at various reaction temperatures; Figure 6 illustrates the location of the potassium atoms near the edge sites and corners in the nanoacstatin CP-MgO; Figure 7 shows an AP-MgO nanocrystal doped with potassium atoms that have dissociated into K + e "; Figure 8 is a graph showing the results of a thermogravimetric analysis of Cl / AP-MgO; Y Figure 9 is a graph showing the results of a thermogravimetric analysis of Br / AP-MgO.

DETAILED DESCRIPTION OF THE INVENTION The following examples represent the preferred methods according to the present invention. However, it should be understood that these examples are provided by way of illustration and nothing in them should be taken as limiting the overall scope of the invention. In these examples, "AP-MgO" and "AP-CaO" refer to the oxides prepared by their respective airgel (or autoclave). "CP-MgO" and "CP-CaO" refers to the respective oxides produced by conventional techniques.

Example ÍA Determination of Surface Areas The Brunauer-Emmet-Teller multiple point gas (BET) absorption method was used using N2 adsorption at liquid N2 temperature to measure the surface area / mass unit. The BET surface area measurement techniques are described in Introduction to the Surface Powder Area, Lowell, S., John Wiley & Sons: New York (1979), incorporated here as a reference.

Example IB Preparation of MgO Samples 1. AP-MgO Highly divided nanocrystalline Mg (0H) 2 samples were prepared by the autoclave treatment described by Utamapanya et al., Chem Ma ter. , 3: 175-181 (1991), incorporated herein by reference. In this procedure, 10% by weight of magnesium methoxide in methanol solution was prepared and 83% by weight of toluene solvent was added. Subsequently, the solution was hydrolyzed by the addition of 0.75% by weight of water by dripping while the solution was stirred and covered with aluminum foil to prevent evaporation. To ensure completion of the reaction, the mixture was kept stirred overnight. This produced a gel which was treated in an autoclave using a miniature Parr glass reactor with a capacity of 600 ml. The gel solution was placed inside the reactor and a jet of nitrogen gas was introduced for 10 minutes, after which the reactor was closed and pressurized to 100 psi using nitrogen gas. Subsequently, the reactor was heated to 265 ° C for a period of 4 hours at a heating rate of 1 ° C / min. The temperature was then allowed to equilibrate at 265 ° C for 10 minutes (the final reactor pressure was 700 psi). At this point, the reactor was vented to release the pressure and vent the solvent. Finally, a sweep was carried out in the reactor with nitrogen gas for 10 minutes. The Mg (OH) 2 particles at dynamic vacuum conditions (10 ~ 2 Torr) at an ascending temperature velocity at a maximum temperature of 500 ° C, which was maintained for 6 hours, resulting in the AP-MgO with a BET surface area of 300 - 600 m2 / g and a crystallite size of 4 nm. Further details about the preparation of MgO can be found in PCT Publication WO 95/27679, also incorporated herein by reference. 2. CP-MgO The CP-MgO samples were prepared by boiling commercially available MgO (Aldrich Chemical Company) for five hours, followed by drying the sample at 120 ° C for five hours. The sample was then dehydrated under vacuum at 500 ° C resulting in CP-MgO with a surface area of 130-200 m2 / g and an average crystallite size of 8.8 nm.

Example 2 Materials and Methods 1. Preparation of the Superbasic Catalyst K / AP-MgO and K / CP-MgO A Schlenk tube of inert atmosphere with a side arm (see Figure 1) was charged 1.0 g of AP-MgO or CP-MgO prepared as described in Example 1 A fresh cut of potassium was placed inside the tube. The system was evacuated, and the side tube was heated to approximately 300 ° C for 30 minutes. All metal potassium was evaporated or adsorbed by the MgO while the MgO was stirred magnetically. 2. Procedure for Isomerization of Alkenes The DMB (2,3-dimethyl-l-butene) or 1-pentene was dried on molecular sieve of 4 Á at room temperature. The K / MgO catalyst prepared in Part 1 of this example (K / AP-MgO or K / CP-MgO) was added to a flask filled with argon. Two ml of DMB (0.0162 moles) or 3 ml of 1-pentene (0.0275 moles) were injected to the catalyst, and the resulting mixture was stirred for 30 minutes at room temperature. 3. Procedure for the Alkylation of Alkenes A 250 ml Hastaloy-C autoclave was placed in an inert atmosphere box, and 0.3 g of K / MgO (K / AP-MgO or K / CP-MgO) was placed in the autoclave. Subsequently, the autoclave was removed from the inert atmosphere box and evacuated. A first alkene gas was allowed to expand into the autoclave at approximately 100 psi and condensed by placing the autoclave in an acetone bath on dry ice. Next, the expansion of a second alkene gas into the autoclave was allowed at a pressure of approximately 100 psi. The moles of alkenes were obtained using the pressure-volume ratio. The sealed autoclave was heated to 180 ° C or 210 ° C for about two hours while maintaining agitation. Then the volatile products of the reaction were collected in cold traps (-78 ° C and -196 ° C) in vacuum.

EXAMPLE 3 Attempt of Isomerization of Alkenes by AP-MgO and CP-MgO Both samples, those of AP-MgO and CP-MgO without potassium were exposed to the DMB following the procedure described in Part 2 of Example 2. The resulting product was analyzed by gas chromatography. The test was repeated with 1-pentene instead of DMB. In no case did the isomerization of alkenes take place. These results indicate that the MgO particles do not possess sufficiently strong basic sites to remove the allylic protons of 1-pentene or DMB.

Example 4 Isomerization of Alkenes by Metallic Oxides with Potassium Loading 1. DMB AP-MgO and CP-MgO (0.1 g) were charged with potassium vapor following the procedures described in Part 1 of Example 2. The potassium loading on the surface of the metal oxide was within the range of 1 to 20% by weight . The contact of two ml of liquid DMB with each sample (AP-MgO or CP-MgO at several potassium loads) was allowed at room temperature for 30 minutes. The resulting material was analyzed by means of gas chromatography in order to determine the percent conversion of DMB to tetramethylethylene. These results are presented in Figure 2 and illustrate that the activity of K / AP-MgO is much greater than the activity of K / CP-MgO. With loads of 10%, 15%, and 20% potassium in AP-MgO, there was about 100% conversion of DMB to tetramethylethylene. For similar charges of potassium in CP-MgO there was only about 10% conversion of DMB to tetramethylethylene. The BET surface area of K / AP-MgO is 128 m2 / g while the BET surface area of K / CP-MgO is 83 m2 / g. Such a substantial difference in percent conversion of DMB to tetramethylethylene can not be attributed solely to the difference in surface areas of K / AP-MgO and K / CP-MgO. Instead, these results indicate that this high conversion with K / AP-MgO is due in part to the reactive edge sites available in the AP-MgO for potassium interaction. 2. 1-Pentene This experiment was repeated using 1-pentene instead of DMB. The results are presented in Figure 3 and indicate that, at a loading of 10% potassium or greater, there was a 90% conversion of 1-pentene to trans / cis-2-pentene. At the same potassium loading in CP-MgO there was a 38-40% conversion of 1-pentene to trans / cis-2-pentene. There was almost no difference in the selectivities of K / AP-MgO and K / CP-MgO towards the formation of cis or trans isomer.

Example 5 Alkylation of Ethylene and Propylene Via Toluene and AP-MgO A 250 ml Hastaloy-C autoclave was placed in an inert atmosphere box, and 0.3 g of AP-MgO was placed with 15% by weight of potassium loading (based on the total weight of the AP-MgO sample) and 10 ml of toluene was placed in the autoclave. Subsequently, the autoclave was removed from the inert atmosphere box and evacuated. The ethylene gas was allowed to expand into the autoclave at approximately 100 psi. The ethylene was condensed by placing the autoclave in an acetone bath on dry ice. The moles of ethylene were obtained by the pressure-volume ratio. The sealed autoclave was heated at 210 ° C for approximately twenty-four hours while stirring. These results are presented in Figure 4 and show that there was approximately 55% conversion of ethylene to C6H5CH2CH2CH3 isomer.

This experiment was repeated using propylene gas instead of ethylene gas with the sealed autoclave heated to 180 ° C (see Figure 4). There was approximately 40% conversion of propylene to isomer C6H5CH2-CH (CH3) 2.

Example 6 Alkylation of Ethylene Through Propylene This experiment was carried out to determine the effect of temperature on the capacity of K / AP-MgO and propylene to rent ethylene. The procedures followed were as described in Part 3 of Example 2 with the exception that the sealed autoclave was heated to 140 ° C, 170 ° C, 210 ° C, or 240 ° C. The results of this experiment are presented in Figure 5 and indicate that, at a 1: 1 molar ratio, the conversion of propylene and ethylene to pentenes and heptenes was carried out at temperatures as low as 140 ° C with maximum conversions taking place at 210 ° C. The percent conversion was only 15% when K / CP-MgO was used at 210 ° C compared to about 55% with K / AP-MgO at 210 ° C. These results provide additional evidence of the importance of sites and corners to provide stronger superbases.

Example 7 Characterization of the Basic Force The basic strengths of several show MgO (both with and without potassium loading) were determined by means of the function used K / CP-MgO at 210 ° C compared to about 55% with K / AP-MgO at 210 ° C. These results provide additional evidence of the importance of sites and corners to provide stronger superbases. " Example 7 Characterization of the Basic Force The basic strengths of several show MgO (both with and without potassium loading) were determined by the H "function of Hammett-Seyrup as described in Hammett, Physical Organic Chemistry, p269 (1940) .The method is presented in detail in Take and collaborators, J. Catal *., 21: 164 (1971), incorporated herein by reference.A short time, an indicator was added to the sample and, if the sample changed the color of the indicator, the basic strength of the sample was determined to be greater than or equal to the basic strength of the indicator.The indicators used in this experiment were 2,4-dinitroaniline (pKBH = 15), 4-chloro-2-nitroaniline (pKBli = 11.2), aniline (pKBr). . = 27), and toluene (pKBH = 35).

The results are shown in Table I below and indicate that the crystallites of the AP-MgO have a greater number of basic sites and basic sites stronger than the CP-MgO. The 4 nm crystallites of surface ions of AP-MgO are found at the corners or at the edges (Klabunde et al., J. Phys. Chem. 100: 12142-12153 (1996)). Therefore 6% (0.2 x 0.3) of all the ions are at the edges or at the corners' corresponding to 1.5 mmoles at the edges / corners per gram of MgO. This value of 1.5 moles is very close to that of the total basic sites of 0.8 mmol / g in the AP-MgO (see Table I).

Table I illustrates that, with the doping of the MgO surface with potassium, the concentration of basic sites increased and stronger sites were generated. Because AP-MgO and CP-MgO do not catalyze isomerization or alkylation reactions of alkenes in the absence of potassium doping (see Examples 3 and 4), the basic sites generated by doping with potassium are responsible for the reactions of isomerization and alkylation. Finally, the surface concentration of strongly basic sites corresponds to the difference in observed catalytic activity (ie, K / AP-MgO exhibits greater catalytic activity than K / CP-MgO).

Comparing the strength of the basic sites of 10% K / AP-MgO with the 15% K / AP-MgO of Table I, there is only a small increase in the basic sites generated with an increase in potassium loading. In addition, the total basic sites coincide almost exactly with the sites calculated for the edges / corners (1.5 mmmol per gram of MgO). This provides additional evidence that edge / corner sites are responsible for the stabilization of reactive molecules in metal oxides. This is the result of electrons trapped near edge / corner sites that enhance basicity at the edges / corners. Figure 6 and 7 illustrate atoms assembled at the dense sites of the edges / corners of the MgO.

Table 1 Basic Strength of Various MgO Samples MgO surface. A larger number indicates a weaker acid. cIndicates the total basic sites.

Discussion of Superbasic Sites Superbasic sites are formed when reactive atoms (eg, potassium) donate their electrons to Lewis acid sites in the vicinity of the corner or edge of the Mg2 + ions, thus creating an additional electron density of neighboring ions 02 ~ in the edge or corner and causing the sites to become supersonic sites. When the potassium vap is the source of metal, each atom that is adsorbed on the surface of the MgO dissociates into K + e ~ in the initial stages, however, the more and more potassium is loaded on the surface of MgO, the surface is covered and the potassium begins to form a layer of potassium metal.The amount of potassium that dissociates depends on the surface area and the number of Lewis acid-base sites available.Surface areas greater than MgO can accept more potassium as K + e ~ with the maximum possible potassium loading as K + e ~ being 30-40% on AP-MgO and 10-20% on CP-MgO.

Exercise 8 Halogenated Metal Oxides The following procedures were followed to prepare halogenated metal oxides. 1. Chlorinated Metal Oxides In order to prepare Cl / MgO or Cl / CaO, the metal oxide samples (each weighing between 0.3 to 10 g) were placed in a Schlenh tube (340 ml vacuum sealed glass tubes 340 ml). Each sample tube was evacuated to room temperature and an excess of chlorine gas was allowed to enter the tube at a pressure of 1 atm of chlorine. The amount of chlorine gas was determined as an excess amount when the incoming gas remained green. The samples became hot to the touch when the chlorine entered the tubes, indicating that a reaction was taking place. The reaction was completed in one or two minutes, but each of the samples was allowed to remain for approximately 30 minutes before being removed from the tube. 2. Brominated Metal Oxides Br / MgO and Br / CaO were prepared in a manner similar to that described in Part I. The entry of bromine gas into the Schlenk tube was allowed, which contained 0.30 to 1.0 g of the particular metal oxide sample. to the vapor pressure of bromine at room temperature. The amount of bromine gas was determined as an excess when the inlet gas remained dark red. The reaction was completed in several minutes, but each of the samples was allowed to stand for approximately 30 minutes before being removed from the tube. 3. Iodized Metal Oxides I / MgO and I / CaO were prepared by placing 1.0 g of the metal oxide in a Schlenk tube together with 1.0 g of iodine. The air was evacuated from the tube, the stopcock was closed, and the sample was heated to 90-100 ° C. The iodine was vaporized and deposited in the oxide particles. The sample was allowed to stand for 30 minutes before being removed from the sample tube.

Example 9 Thermogravimetric Analysis (TGA) The following experiments were performed to determine the number of atoms of a halogen adsorbed on each square nanometer of the surface of the metal oxide. In each of these tests, the average weight loss of a halogenated metal oxide sample was determined and compared to an average weight loss of an unhalogenated metal oxide sample to determine the weight percent of the halogenated sample which is attributed to halogen. This percent was used to obtain the number of halogen atoms adsorbed per square nanometer of metal oxide. 1. AP-MgO with Chlorine Approximately 1.0 g of AP-MgO was treated with excess chlorine gas following the procedure described in Part 1 of Example 8. The light yellow sample was transferred in air to a TGA Shimadzu apparatus (there was no change in color) . The chamber was flushed with nitrogen and the TGA was made (ie, the chlorinated metal oxide was heated to 700 ° C at 10 ° C / min by measuring the weight of the mixture continuously in order to determine the loss in weight of each sample). This experiment was repeated several times illustrating one of these results in Figure 8.

The same TGA procedure was followed for a sample of non-chlorinated metal oxide. The weight losses for AP-MgO and for Cl / AP-MgO heating up to 700 ° C were determined as follows: AP-MgO 11.3 + 0.5 average weight loss Cl / AP-MgO 24.2 + 1 average weight loss Assuming that all the chlorine was desorbed at 700 ° C, and that there were x grams of chlorine per 1.0 gram of AP-MgO: x = (24.2% -11.3%)? X = 0. 147g Cl2 in l. Og of AP-MgO ; i. 0g + x) lmol Cl2 1000 mmol (0.147g Cl2) = 2.08 mmol of Cl2 vig 1 mol (2.08 mmol Cl2) (2) = 4.16 mmol of Cl2 atoms Surface area of AP-MgO = 430 nm2 / g So, rg. l ßmmol atom. C_, r (4.16xl0 ~ 3mol / g) (6. 02xl023atom / mol) - l. Og AP-MgO 430xl018 nnr / g Therefore, 5.8 atoms per nm2 of AP-MgO were absorbed 2. AP-MgO with Bromine An AP-MgO (l.Og) sample was treated with excess bromide as described in Part 2 of Example 8. The light brown colored sample was transferred in air to a TGA apparatus (no change color) . The chamber was flushed with nitrogen and the TGA was made. After four repetitions, the average weight loss was determined at 13%. One of these results is illustrated in Figure 9. The number of Br atoms adsorbed on each square nanometer of AP-MgO was calculated in the same manner described in Part 1 of this example. Assuming that all the bromine was desorbed at 700 ° C, and that there were x grams of bromine per 1.0 grams of AP-MgO: 13%? x = 0.149g Br2 in l.Og of AP-MgO (l.Og + x) lmol Br2 1000 mmol (0.149g Cl2) = 0.932 mmol of Br2 159.8g 1 mol (0.932 mmol Br2) (2) = 1864 mmol Br atoms Surface area of AP-MgO = 430 nm2 / g Then, 4. 16mmol atom. Br (1 864xlCT3mol / g) (6. 02xl023atom / mol) = 2. 6 Cl atoms / nm2 l. Og AP-MgO 430xl018 nmVg 3. AP-MgO with Iodine One gram of AP-MgO sample was treated with 1 g of iodine following the procedure described in Part 3 of Example 8. The sample was transferred in air to the TGA apparatus (no color change). The chamber was flushed with nitrogen and the TGA was performed. This test was repeated several times and the average weight loss was determined at 15%. The number of I atoms adsorbed on each square nanometer of AP-MgO was calculated in the same manner described in Part I of this example. Assuming that all iodine was desorbed at 700 ° C. and that there were x grams of iodine per 1.0 grams of AP-MgO: x 15í x = 0.176g I2 in l.Og of AP-MgO (l.Og + x) lmol I2 1000 mmol (0.176g Cl2) 0.693 mmol of I2 253.8g 1 mol (0.693 mmol I2) (2) = 1.39 mmol of? Surface area of AP-MgO = 430 nm2 / g Then, 1. 39mmol atom. I (1.39xl 0 ~ 3mol / g) (6. 02xl 023atom / mol) = 2. 01 atom I / nm2 l. Og AP-MgO 430xl018 np / g Therefore, 2.0 I atoms were adsorbed per nm2 of AP-MgO.

Example 10 Repeated Adsorption of Chlorine Atoms on AP-MgO A series of experiments was performed on the same metal oxide sample to determine if the Cl2 adsorption-desorption was reversible. The tests were carried out as follows: (a) Chlorine was adsorbed to AP-MgO following the procedure of Example 8. Then, following the procedures presented in Part 1 of Example 9, it was determined that the loss in% by weight due to chlorine was 14%. (b) The sample from step (a) was heated at 500 ° C under vacuum for 4 hours. (c) Step (a) was repeated in the sample of step (b) and it was determined that the loss in% by weight due to chlorine was 10%. (d) The sample from step (c) was heated at 500 ° C under vacuum for 4 hours. (e) Step (e) was repeated in the sample of step (d) and it was determined that the loss in weight percent due to chlorine was 4.5%.

With each repetition of adsorption and desorption, the percent by weight loss of the sample decreased, indicating that the adsorption of chlorine on the metal oxide and the desorption of chlorine from the metal oxide are not completely reversible.

Example 11 Absence of Chlorination of 2,3-dimethylbutane (DMBA) with Cl 2 (without AP-MgO or light IV) Cl 2 (14 mmol) and DMBA (14 or 28 mmol) were mixed in a Schlenk glass tube at room temperature in the dark. The sample was analyzed by gas chromatography. No peaks were observed in the chlorinated alkane region, thus indicating that no reaction took place.

Example 12 Chlorination of DMBA with UV light Cl2 (14 mmol) and DMBA (14 or 28 mmol) were mixed in a quartz tube of photolysis and irradiated with unfiltered UV light (450 Watt lamp). The sample was analyzed by gas chromatography and indicated that a mixture of mono- and dicloration products was formed.

Example 13 Chlorination of DMBA in the presence of MgO or CaO samples without UV light.

Several criteria were used to contact chlorine, metal oxide and light. • (a) First, DMBA was added to a Schlenk tube containing AP-CaO. When Cl2 was added to the sample tube, an explosive reaction was observed. The same result was found when this procedure was repeated with CP-CaO. (b) Cl2 was added to a Schlenk tube containing AP-CaO. The heat of adsorption was allowed to dissipate until the sample was at room temperature to then introduce DMBA. Chlorination products formed, but no explosion occurred. (c) Cl2 was added to a tube containing CP-CaO. The heat of adsorption was allowed to dissipate until the sample was at room temperature (25 ° C) to then introduce DMBA. A violent reaction took place. This same result occurred when DMBA was introduced into the sample at sample temperatures of 0 ° C and -23 ° C. However, when DMBA was introduced into the Cl / CP-CaO sample at sample temperatures of -42 ° and -78 ° C, no explosion occurred. Instead, the reaction mixture was slowly heated to room temperature. Similar experiments were performed with AP-MgO at sample temperatures of 25 ° C, 0 ° C, -42 ° C and -78 ° C. Again, explosions occurred at 25 ° C and 0 ° C, but at temperatures of -42 ° C and -78 ° C, mild chlorination of DMBA took place.

Example 14 Determination of the Selectivity of the Chlorination Reactions A series of experiments were carried out with CP-CaO, AP-CaO, and AP-MgO following the procedures described in Example 8. The DMBA was added to the samples of chlorinated metal oxide at sample temperature. 42 ° C and -78 ° C, and the mixture was kept at the lowest temperature (that is, either at -42 ° C or -78 ° C for several hours). The volatile materials were removed by vacuum from the heated sample to room temperature.

Analysis of the products by GC-MS showed the presence of a mixture of mono-, di-, and trichloro-alkanes. It was found that the reaction temperature and the ratio of C12: DMBA affected the probability of formation of several products. The results are summarized in Table II. The order of reactivity (more reactive to least reactive) was AP-MgO > CP-CaO > AP-CaO. The lower temperatures decreased the selectivity of the chlorination of the tertiary C-H bond, thus resulting in an increase in the monoalkanes. These results are important because the above reaction temperatures of 200-300 ° C or exposure of the reaction mixture to ÜV light was necessary in order to chlorinate the alkanes.

Table II The selectivity of chlorination reaction under different conditions - Example 15 Bromination of DMBA Br2, DMBA, and CP-CaO were mixed in molar ratios of 1: 1 in the dark and at room temperature. After 24 hours the reaction mixture was inspected for the loss of red-brown color due to the consumption of Br2. This same test was repeated for AP-MgO and AP-CaO. Qualitatively it was found that the presence of oxides accelerated the reactions. The reactions proceeded in the following order (from the fastest to the slowest) thus indicating the ability of each metal oxide to capture bromine: CP-CaO > AP-MgO > AP-CaO > no rust present.

Example 16 Yoduration of DMBA with I2 The iodination of DMBA was attempted in a series of experiments. The following mixtures were tested: I2 + DMBA + UV light; I2 + DMBA + AP-CaO (both with and without UV light); I2 + DMBA + CP-CaO (both with and without UV light); and I2 + DMBA + AP-MgO (both with and without UV light). No iodination reaction occurred in any of the experiments.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (80)

1. A composition, characterized in that it comprises a metal oxide particle with a number of atoms stabilized on its surface, said atoms selected from the group consisting of halogens and metals of Group I and being present at a level of at least 2 atoms per square nanometer of surface area of metallic oxide.
2. The composition according to claim 1, characterized in that said particle has an average crystallite size of up to 20 nm.
3. The composition according to claim 2, characterized in that said average crystallite size is about 3-6 nm.
4. The composition according to claim 3, characterized in that said crystallite size of about 4 nm.
5. The composition according to claim 1, characterized in that said particle has a multiple dot surface area of at least about 15 m2 / g.
6. 6. The composition according to claim 5, characterized in that said surface area is at least 200 m2 / g.
7. 7. The composition according to claim 6, characterized in that said surface area is at least 500 m2 / g.
8. The composition according to claim 1, characterized in that said particle is selected from the group consisting of MgO, CaO, TiO2, ZrO2, FeO, V205, Mn203, Fe203, NiO, CuO, A1203, ZnO, and mixtures thereof.
9. 9. The composition according to claim 8, characterized in that said particle is MgO.
10. 10. The composition according to claim 8, characterized in that said particle is CaO.
11. 11. The composition according to claim 1, characterized in that said atom is a chlorine atom.
12. The composition according to claim 1, characterized in that said level is 3-8 atoms per square nanometer of the surface area of the metal oxide.
13. The composition according to claim 11, characterized in that the composition has a hydroxyl surface concentration of less than about 5 hydroxyl groups per square nanometer of metal oxide surface area.
14. A method for the formation of a metal ion / reactive atom composition, characterized in that it comprises the steps of: (a) provision of a quantity of metal oxide particles; (b) contacting said particles with a source of reactive atoms selected from the group consisting of halogen atoms and metals of group I under conditions to link said atoms to the surfaces of said particles at a level of at least 2 atoms per square nanometer of oxide particle surface area.
15. 15. The method according to claim 14, further characterized includes the steps of heating said particles to at least 200 ° C before step (b).
16. 16. The method according to claim 14, characterized in that said particles are selected from the group consisting of MgO, CaO, TiO2, ZrO2, FeO, V205, Mn203, Fe203, NiO, CuO, A1203, ZnO, and mixtures thereof.
17. 17. The method according to claim 16, characterized in that said particle is MgO.
18. 18. The method according to claim 16, characterized in that said particle is CaO.
19. 19. The method according to claim 14, characterized in that said atoms are halogens.
20. 20. The method according to claim 19, characterized in that said atoms are chlorine atoms.
21. 21. The method according to claim 14, characterized in that said particles have a multiple dot surface area of at least about 15 m2 / g.
22. The method according to claim 21, characterized in that said surface area is at least 200 m2 / g.
23. The method according to claim 22, characterized in that said surface area is at least 500 m2 / g.
24. The method according to claim 14, characterized in that said source of reactive atoms comprises a compound which under these conditions dissociates to generate said reactive atoms.
25. The method according to claim 14, characterized in that said particles have an average crystallite size of up to 20 nm.
26. The method according to claim 25, characterized in that said particles' have an average crystallite size of about 3-6 nm.
27. The method according to claim 26, characterized in that said crystallite size is 4 nm.
28. The method according to claim 15, characterized in that it additionally includes the step of cooling said particles to a temperature of about -20 ° C to about 25 ° C after said heating step.
29. The method according to claim 20, characterized in that the product of step (b) has a total surface concentration of hydroxyl groups of less than 5 hydroxyl groups per square nanometer of metal oxide surface area.
30. A method for altering species, characterized in that it comprises the steps of: (a) provision of a quantity of the composition of claim 1; and (b) contacting said composition with said species.
31. The method according to claim 30, characterized in that said spice is unsaturated.
32. 32. The method according to claim 31, characterized in that said species is an alkene.
33. 33. The method according to claim 30, characterized in that said species is saturated.
34. 34. The method according to claim 33, characterized in that said species is an alkane.
35. 35. The method according to claim 30, characterized in that said particle is selected from the groups consisting of MgO, CaO, TiO2, ZrO2, FeO, V205, Mn203, Fe203, NiO, CuO, A1203, ZnO, and mixtures thereof.
36. 36. The method according to claim 35, characterized in that said particle is MgO
37. 37. The method according to claim 35, characterized in that said particle is CaO.
38. 38. The method according to claim 30, characterized in that said atom is a chlorine atom.
39. The method according to claim 30, characterized in that said particle has a crystallite size of up to 20 nm.
40. The method according to claim 39, characterized in that said particle has an average crystallite size of about 3-6 nm.
41. The method according to claim 33, characterized in that said particle has a crystallite size of about 4 nm.
42. The method according to claim 30, characterized in that said contacting step takes place at a temperature of about -80 to about 240 ° C.
43. The method according to claim 30, characterized in that said contact step occurs in the absence of UV light.
44. 44. The method according to claim 30, characterized in that said particle has a multiple dot surface area of at least 15 m2 / g.
45. 45. The method according to claim 44, characterized in that said surface area is at least 200 m2 / g.
46. 46. "The method according to claim 45, characterized in that said surface area is at least 500 m2 / g.
47. 47. The method according to claim 38, characterized in that said composition has a total concentration of hydroxyl group of less than about 5 hydroxyl groups per square nanometer of metal oxide surface area.
48. 48. The method according to claim 30, characterized in that said atom is of potassium.
49. 49. The method according to claim 30, characterized in that it additionally comprises the steps of contacting the product of step (b) with a second species, said second species being unsaturated.
50. The method according to claim 49, characterized in that said second species is - an alkene.
51. The method according to claim 49, characterized in that said atom is a potassium atom.
52. The method according to claim 51, characterized in that said concentration of potassium atom is about 20% by weight based on the total weight of said metal oxide.
53. The method according to claim 49, characterized in that said particle has a multi-point surface area of at least 15 m2 / g.
54. The method according to claim 53, characterized in that said surface area is at least 200 m2 / g.
55. The method according to claim 54, characterized in that said surface area is at least 500 m2 / g.
56. The method according to claim 49, characterized in that said first species is propylene and said second species is ethylene.
57. The method according to claim 49, characterized in that said first contacting step is carried out at a pressure of the first species of about 80-120 psi and said second contacting step is carried out at a pressure of the second one. kind of an 80-120 psi.
58. A combination, characterized in that it comprises a self-supported body formed by numerous particles of metal oxide agglomerated with a. a number of atoms stabilized on its surface, said atoms selected from the group consisting of halogens and metals of group I, said atoms being present at a level of at least about 2 atoms per square nanometer of the surface area of the metal oxide.
59. The combination according to claim 58, characterized in that said particles are selected from the group consisting of MgO, CaO, TiO2, ZrO2, FeO, V205, Mn203, Fe203, NiO, CuO, A1203, ZnO, and mixtures thereof.
60. The combination according to claim 59, characterized in that said particles with MgO.
61. The combination according to claim 59, characterized in that said particles are CaO.
62. The combination according to claim 58, characterized in that said particles have stabilized surface atoms being pressed at a pressure of about 50 psi to about 6,000 psi.
63. The combination according to claim 62, characterized in that said particles have stabilized surface atoms being pressed at a pressure of about 500 psi to about 5,000 psi.
64. The combination according to claim 63, characterized in that said particles have stabilized surface atoms being pressed at a pressure of about 2,000 psi.
65. The combination according to claim 58, characterized in that said particles having stabilized surface atoms are pressed together.
66. A composition, characterized in that it comprises a metal oxide particle with a number of atoms stabilized on its surface forming an adduct of metal oxide-atom, where when said adduct is heated to a temperature of about 100 ° C less than 10% the losses in the total weight of the adduct is attributable to the desorption of said atoms.
67. The composition according to claim 66, characterized in that said atoms are selected from the group consisting of halogens and Group I metals.
68. The composition according to claim 66, characterized in that said atoms are present at a level of at least about 2 atoms per square nanometer of the surface area of the metal oxide.
69. The composition according to claim 68, characterized in that said level is about 2 to 14 atoms per square nanometer of the surface area of the metal oxide.
70. The composition according to claim 66, characterized in that said particle has an average crystallite size of about 20 nm.
71. 71. The composition according to claim 70, characterized in that said average crystallite size is 3-6 nm.
72. 72. The composition according to claim 71, characterized in that said average crystallite size is 4 nm.
73. 73. The composition according to claim 66, characterized in that said particle has a multiple dot surface area of at least 15 m / g.
74. 74. The composition according to claim 73, characterized in that the surface area is at least about 200 m2 / g.
75. 75. The composition according to claim 74, characterized in that said surface area is at least about 500 m2 / g.
76. 76. The composition according to claim 66, characterized in that said particle is selected from the group consisting of MgO, CaO, TiO2, ZrO2, FeO, V2Os, Mn203, Fe203, NiO, CuO, A1203, ZnO, and mixtures thereof.
77. 77. The composition according to claim 76, characterized in that said particle is MgO.
78. 78. The composition according to claim 76, characterized in that said particle is CaO.
79. 79. The composition according to claim 66, characterized in that said atom is a chlorine atom.
80. 80. The composition according to claim 79, characterized in that said composition has a surface hydroxyl concentration of less than 5 hydroxyl groups per square nanometer of the surface area of the metal oxide.