NO140895B - PROCEDURE FOR THE PRODUCTION OF INORGANIC FIBERS - Google Patents

Description

The invention relates to a method for production

of inorganic fibres, comprising fiber formation by blowing a mixture having a viscosity above 1 poise, comprising a solvent and a metal compound, the metal compound being selected from the chlorides, sulphates, acetates, formates, hydroxides and nitrates of aluminium, iron, zirconium, titanium, beryllium , chromium, magnesium, thorium, uranium, yttrium, nickel, vanadium, manganese, molybdenum, tungsten and cobalt. Furthermore, the mixture comprises 0.1-10% by weight,

based on the total weight of the mixture, of an organic polymer with a molecular weight in the range 10 3 -10 7. Both the metal compound and the organic polymer are soluble in the solvent, and the weight share of the organic polymer is below 10% of the weight share of the metal compound.

After fiber formation, at least part of the solvent is removed from the fibers produced, and the fibers are heated to split the metal compound and/or the organic polymer.

The method according to the invention is characteristically

characterized by fiber formation being carried out by extruding said mixture through one or more openings into at least one gas

stream that has a high-velocity component in the extrusion direction

gen to the extruded mixture. The fiber-forming mixture contains possibly a catalyst material or a precursor for this.

It is understood that the metal compound is soluble

in the solvent when it is able to form a true solution or a colloidal solution (a sol) with the solvent.

The weight proportion of the metal compound in the said mixture

is greater than the weight proportion of the organic polymer,

e.g. when there is at least twice as much metal compound as

organic polymer present. More particularly, the organic polymer constitutes less than 10% by weight of the metal compound, e.g. 2-8

wt%, or in some embodiments 0.1-2 wt%.

The metal compound is a water-soluble metal compound-

see, e.g. a metal salt (which may be a basic salt) that gives a viscous solution or sol in water. The water-soluble metal compound

part can advantageously be selected from the group consisting of chlorides,

sulphates, acetates, formates, hydroxides and nitrates of aluminum

minium, iron, zirconium, titanium, beryllium, chromium, magnesium,

thorium, uranium, yttrium, nickel, vanadium, manganese, molybdenum,

tungsten and cobalt or mixtures thereof. Especially preferred

are metal salts which can form a refractory oxide, in particular aluminum oxychloride, basic aluminum acetate, basic aluminum formate, zirconium oxychloride, basic zirconium acetate, basic zirconium nitrate or basic zirconium formate, mixtures of these or

mixed salts thereof.

The solvent is a polar solvent, e.g. one

alcohol, especially methanol or ethanol, glacial acetic acid, dimethylsulfoxide or dimethylformamide. It is particularly convenient to use water as a solvent. Mixtures of solvents may be used.

The organic polymer is a water-soluble organic polymer,

preferably a non-ionic water-soluble organic polymer, a polyhydric

sylated organic polymer or a natural water-soluble rubber. The organic polymer is preferably heat stable under the conditions of fiber formation, e.g. from ambient temperature to a few degrees above the boiling point of the solvent. Examples of preferred organic polymers are:

partially hydrolyzed polyvinyl acetate

polyvinyl alcohol

polyactylamide and partially hydrolyzed polyacrylamide

polyacrylic acids

polyethylene oxides

carboxyalkyl celluloses, e.g. carboxymethyl cellulose

hydroxyalkyl celluloses, e.g. hydroxymethyl cellulose

alkyl celluloses, e.g. methyl cellulose

hydrolyzed starches

dextrans

guar gum

polyvinyl pyrrolidones

polyethylene glycols

alginic acids

polyisobutylene derivatives

polyurethanes, and

esters, copolymers or mixtures thereof.

Most preferred organic polymers are straight-chain polyhydroxylates of organic polymers, e.g. polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, polyethylene oxide or polyethylene glycol.

The molecular weight of the organic polymer lies in the range 10 3 to 10 7 , preferably as high as is compatible with the ability of the organic polymer to dissolve in the solvent used in the method according to the invention. For example, it is preferred that the polyvinyl alcohol or the partially hydrolyzed polyvinyl acetate has a medium or high molecular weight,

4 6

that the polyethylene oxide has a molecular weight of 10 -10 and that the polymers originating from cellulose have a molecular weight of 10,000 to 50,000.

It is preferred that the concentration of organic polymer

in the fiber-forming mixture is from 0.1 to 2% by weight.

It is preferred that little or no chemical reaction occurs between the metal compound and the organic polymer in the fiber-forming mixture.

The viscosity of the fiber-forming mixture should be above 1 poise. Conveniently, the viscosity is in the range of 1-3000 poise, preferably 100-1000 poise, especially when the fiber formation is carried out by extruding the mixture through a spinning die to form a continuous filament. Fiber formation of low viscosity mixtures, e.g. 1-100 poise, is preferably carried out by a blowing process which will be described below.

Fiber formation by blowing comprises extruding the fiber-forming mixture through one or more openings into at least one gas stream having a high velocity component in the outflow direction of the extruded mixture. The dimensions and shape of the said opening can vary within wide limits.

It is preferred to use an aperture having at least one dimension greater than 50 microns and less than 500 microns. gas-electric-

but is preferably air, more preferably air at ambient temperature. It is convenient to use two gas streams which converge at or near the point where the mixture is extruded from the orifice. Preferably, the angle between the converging gas streams is from 30 to 60°. At least part of the solvent in the mixture is removed by the gas stream, and the removal rate can be conveniently regulated by mixing the gas with the solvent vapor, and e.g. air with a relative humidity above 80% can be used, especially for aqueous mixtures. The speed of the gas flow can be varied within wide limits, but it is preferred to use speeds in the range of 60 to 450 m/sec. The pressure used to extrude the mixture through the openings will depend on the viscosity of the mixture and on the desired extrusion speed. It has been found that pressures from 0.07 to 7 kg/cm are absolutely suitable for mixtures with viscosities up to approx. 100 poise.

The fibers produced by blowing generally have a small diameter, typically 0.5-5.0 microns, and are generally available in interrupted lengths, which may, however, have very high ratios between length and diameter, e.g. over 5000. The fibers can be collected as single kelt fibers or in the form of a yarn, a mat or felt. If desired, the fibers can be tied together, e.g. by collecting the fibers before they dry and heating the resulting mat or felt. Binding of the fibers can be carried out using a binding agent.

The fiber-forming mixture can be conveniently prepared by

to dissolve the metal compound and the organic polymer in the solvent. The order in which the resolution is performed is not usually critical and can be chosen for maximum convenience in each embodiment. An aqueous sol can often be made by hydrolysis or heating of an aqueous solution of the metal compound. The metal compound or organic polymer can be formed from a suitable precursor, usually in the presence of the solvent. It may be convenient to concentrate the solution, preferably after filtration to remove solids, e.g. by evaporation of a part of

the solvent to achieve the required viscosity for fiber formation. Optionally, the fiber-forming mixture can be deaerated before fiber formation.

It is preferred to remove solvent from the fibers which are formed by fiber formation by evaporation, e.g. by heating at a temperature from 30 to 110°C, possibly under reduced pressure.

The fiber is further heated to split the metal compound and/or the organic polymer to form a fiber of a different composition. Particularly important are embodiments where it is desirable to make a fiber consisting of a refractory metal oxide, e.g. alumina or zirconium oxide. Typically, the fibers can be heated at a temperature from 100 to 2000°C for from 5 minutes to 24 hours. The refractory fiber that forms can optionally be sintered by further heating at a temperature from 500 to 2000°C in e.g. 5 minutes to 4 hours. Heating for cleavage or sintering can be carried out in stages, e.g. in successive steps with increasing temperature.

During fiber formation and/or solvent removal and/or further heating, the fibers may be subjected to tension.

Various additives can be incorporated into the fibres, individually or in any combination, preferably by adding them to the fibre-forming mixture. Additives can also be added to the surface of the fibers by any suitable treatment process. Examples of additives that can be added are: (a) grain weight inhibitors, e.g. compounds of magnesium, calcium or aluminium, (b) sintering aids, e.g. fluorides or salts

of sodium or potassium,

(c) surfactants, e.g. alcohols,

(d) stabilizers for the fiber-forming mixture, e.g.

formic acid, acetic acid or tartaric acid,

(e) phase change stabilizers, e.g. compounds of lithium, calcium, magnesium, hafnium, yttrium, the lanthanides or boric acid, (f) reinforcing particles such as e.g. colloidal silicic acid,

e.g. silicic acid made by a plasma process,

(g) a compound which improves the refractory properties

by a refractory fiber, e.g. acid oxides, especially SiO2/ B2O3 or P2°5 or compounds that decompose

for the formation of acidic oxides,

(h) catalyst materials, e.g. compounds of platinum,

copper, palladium, silver, ruthenium, nickel, cobalt, chromium, iron, titanium, vanadium or manganese as described

in the following,

(i) luminescent salts, e.g. salts of thorium or

cerium,

(j) coloring agents, e.g. mordant dyes or pigments.

For embodiments where fibers comprising zirconium oxide are produced, it is preferred to use aluminum oxide as a grain growth inhibitor, preferably from 0.2 to 20% by weight, based on the zirconium oxide content. As a phase change stabilizer for said fiber, it is preferred to use yttrium oxide or calcium oxide, preferably from 2 to 15% by weight of the zirconium oxide. It is particularly preferred to use aluminum oxide in combination with yttrium oxide or calcium oxide in a zirconium oxide-containing fiber.

The fibers produced according to the invention can be processed with a large amount of materials. For example, they can be coated with a coating agent, e.g. polyvinyl alcohol or stearic acid. They can be immersed in a solution of ethyl silicate, washed and heated so that a fiber containing silicon oxide is obtained. They can also be soaked in solutions of metal salts, and the treated fibers can be heated so that a fiber containing additional refractory metal oxide is obtained.

The method according to the invention thus provides a fiber comprising a metal compound and an organic polymer which can be in infinite or interrupted lengths or in the form of a mass or felt. The weight proportion of the metal compound in the fibers is greater than the weight proportion of the organic polymer. Thus the organic polymer makes up less than 10% by weight of the metal compound, e.g. 2-8% by weight, preferably 0.1-2% by weight.

With the method according to the invention, a continuous, discontinuous or felted fiber of refractory metal oxide can be produced, e.g. a fiber comprising aluminum oxide or zirconium oxide. The zirconium oxide is preferably in its tetragonal or cubic form. Usually have

the fibers an average diameter of from 0.5 to 50 microns,

although the method is not limited to the production of fibers in this diameter range. Fibers with diameters from 0.5 to 5 microns are particularly useful, as they are strong and flexible. If desired, the continuous fibers can be converted into short lengths, or the fibers can be made to any suitable length.

As mentioned earlier, the fiber-forming mixture may contain a catalyst material or a precursor thereof.

The catalyst material may be present on the surface of the fiber or may be incorporated so that it is inside the fiber. Optionally, the catalyst material can be partly inside the fibers and partly on the surface.

When at least part of the catalyst material is included in the fibers, it is appropriate to disperse the catalyst material,

or a precursor thereof in the fiber-forming mixture.

It is preferred to disperse the catalyst material or its precursor in a fiber-forming mixture comprising an aluminum or zirconium compound. By catalyst material precursor is meant a material which, when suitably treated, e.g. on heating or reduction, will provide a catalyst material, directly or indirectly.

Particularly conveniently, the catalyst material can be dispersed in said mixture by dissolving it, or its precursor, in said mixture. It is preferred to dissolve water-soluble materials, e.g. salts of catalytic metals, especially metal nitrates, in aqueous fiber-forming compositions.

The dispersion of the catalyst material in the fiber-forming mixture can also be carried out by mixing insoluble or partially soluble particulate catalyst material with the fiber-forming mixture. Preferably, the average size of the particles thus dispersed should be less than the average diameter of the fiber produced, and more particularly the particles should be of colloidal size.

Any desired amount of catalyst material may be dispersed in the fiber-forming mixture, provided that the fiber produced is still sufficiently strong and coherent for use as a fiber catalyst. It turns out that up to approx. 5%

of a catalyst material of suitable size can be incorporated into the fibers without serious deterioration of the fiber properties.

It is preferred that the catalyst material is chemically compatible with the constituents of the fiber-forming mixture.

When the fibers are heated to form e.g. a refractory metal oxide, as described here, it is preferred that the catalyst material is stable at the heating temperature. In the case of a catalyst material precursor, it is often convenient that the catalyst is formed from the precursor during the heating of the fibers.

The catalyst material can be incorporated into the fibers by soaking the fibers in a solution of the catalyst material or a catalyst material precursor in a suitable solvent, after which the solvent is removed from the fibers. Water is a suitable solvent for many catalyst materials or their precursors, e.g. metal salts. A fiber can be soaked before or after it is heated to form a fiber of a different composition, as described here.

The catalyst material can preferably be deposited in a suitable form on at least part of the fiber surface. For this purpose, it can, if desired, be bound to the surface by means of a binding agent, which can itself be a catalyst material, e.g. aluminum phosphate. Bonding can also be carried out by means of an application of fiber-forming mixture on the surface or on the catalyst material or both, and removal of the solvent from said mixture. Organic polymer materials can also be used to bind the catalyst to the fiber surface.

If no binder is used to aid in the attachment of the catalyst material to the fiber surface, it is often possible to induce chemical reaction between the catalyst material and the fibers to improve bonding. In most embodiments of the invention, however, it is satisfactory to simply deposit the catalyst material on the fiber surface in a form sufficiently fine for the normal forces of physical attraction to take place. Thus, it is practical to deposit the catalyst material from a mist or vapor comprising the catalyst material or its precursor. It is most practical to deposit the catalyst material or its precursor on the fiber surface by treating the surface with a dispersion comprising the catalyst material or its precursor and a suitable liquid. A solution of the catalyst material or its precursor in a volatile solvent is particularly useful. If the catalyst material is dispersed in a liquid that does not dissolve it, it is preferred that the catalyst material be in finely divided form, most preferably with an average size below 0.5 microns.

The catalyst material can be further processed, for example to bring about desired changes. For example, in the case where a catalyst material precursor is incorporated in or on the fibres, it will be necessary to produce the active catalyst material by a suitable process. The methods normally used include chemical reaction to form another compound, reduction and heating. Any of these methods, especially heating,

can be combined with the step of heating the fibers to decompose the metal compound or the organic polymer in the fiber-forming mixture. Treatment of the catalyst material to achieve desirable physical changes can also be carried out. For example, it may be desirable to have changes in the surface area or the crystal structure to achieve specific catalytic effects. Treatment to remove unwanted substances, e.g. catalyst poisons, may be useful in some embodiments.

A very large number of catalyst materials can be used, and the products produced with these can be used in a large number of chemical processes of industrial importance.

Phosphoric or sulfuric acid as a catalyst material provides a product useful as a catalyst in adiponitrile synthesis, in the polymerization of mixed olefins to gasoline, the hydration of olefins to alcohols, and the alkylation of aromatics.

Products produced according to the invention, which comprise the metals copper, rutenlum, nickel, palladium, platinum or silver, or combinations thereof, are particularly useful in methods such as e.g. the following:

dehydration of alcohols,

methanol synthesis

reduction of nitrobenzene

ammonia splitting

steam reforming of petroleum or natural gas hydrogenation of olefins, aromatics, nitrides, fats and oils sulfur dioxide oxidation

hydro-dealkylation

methane ammoxidation

ethylene oxide from ethylene

formaldehyde from methanol.

The use of alumina fibers in some of these reactions is preferred, especially in cases where the correct alumina phase is used, e.g. in the Jf or 7[ form.

Semiconductor oxides are useful catalyst materials.

For example, Cr2O3 on f- or Tt-alumina can be used for paraffin dehydrogenation or petroleum reforming.

Metal halides, e.g. CuCl2, SbCl3, AlCl3 or CrCl-j give products which are useful as catalysts for many chlorination or oxychlorination reactions or for the isomerisation of paraffins, olefins and aromatics.

Organo-metallic catalysts can best be used in connection with the invention by soaking or coating the previously formed fiber. Such fiber catalysts are useful in the production of ethylene oligomers, polyethylenes and polyesters. Metal carbonyls, e.g. HCo(CO)4, provide fiber catalysts useful for carrying out "0X0" processes.

The fiber catalysts, especially those containing platinum, palladium, molybdenum, Co 3 O 4 , V 2 O 2 -, Cr 2 O 3 , MnO 2 , Fe 2° 3 or NiO or combinations thereof, can be used to catalyze the oxidation of car exhaust gases, e.g. in an afterburner.

Other catalytic materials found useful include:

cobalt molybdate

nickel molybdate

bismuth molybdate

copper molybdate

zinc chromite

cobalt oxide, Co-jO^ .

Fiber catalysts produced according to the invention are advantageous because of their high external surface areas. Fiber catalysts comprising a refractory oxide, especially aluminum oxide or zirconium oxide, are heat-resistant and mechanically strong.

The invention is thus useful in the production of fibers which can have a very small diameter, are dense, refractory, strong and have a high modulus. They can be advantageously used at high temperature as insulating materials, fillers, as a reinforcing agent for resins, metals and ceramic metals, inert filters, catalysts or catalyst carriers. The fibers can be spun into yarn that can be woven into fabric.

In the following, the invention will be illustrated by examples.

Example 1

An aluminum oxychloride solution with a molar ratio A1:C1 of 1.8:1 was prepared by reaction between pure aluminum powder and a solution containing 260 g/l of aluminum chloride under reflux conditions. The solution was carefully filtered through a fine, acid-resistant filter paper.

A 2% by weight solution of a partially hydrolyzed cold water soluble high molecular weight polyvinyl acetate was made by stirring in distilled water for 6 hours. The solution was filtered and

filtered.

When the polymer solution was free of bubbles, 25 ml

added to 50 ml of the aluminum oxychloride solution, along with 5 drops of glacial acetic acid. The resulting mixture was evaporated onto

a standard low laboratory rotary evaporator at 35°C under redu-

hard pressure. 2 hours that the rotary evaporator was stopped,

the solution had a viscosity of 360 poise at a shear rate of

heat of 200 sec and a viscosity of 700 poise at extra-

polishing at 0 shear rate, measured on a Ferranti-Shirley cone-plate viscometer.

The solution was introduced into a stainless steel pressure vessel

and extruded under nitrogen pressure via a 10 micron pore size millipore filter through a 100 micron diameter spinneret.

The extruded fiber was wound up at a rate of

of 180 m/min after it had passed through 46 m of air at a temperature of 25°C and relative humidity 60%.

The diameter of the recovered fiber was 5 microns.

Tensile tests on an Instron tester equipped with an A-

cell and which gave a 2 g full-scale graphic reading, gave tensile

strength in the region of 840 to 1050 kg/cm 2.

Upon further heating, the fibers became black on the ground

of the splitting of the polymer, and the coal burned off at temperatures above 500°C so that a white, glassy fiber was obtained.

Example 2

A 2% by weight solution of a water-soluble polyvinyl alcohol

of medium molecular weight was made by stirring the polyvinyl alcohol granules into water overnight. The solution was strained and filtered.

50 ml of this solution was added to 50 ml of an aluminum oxychloride solution which, by analysis, was found to contain

keep 11.2 wt% aluminum and 8.1 wt% chlorine. 3 drops of glacial acetic acid were added to the mixture as a stabilizer. The solution was evaporated under reduced pressure on a rotary evaporator to give a viscosity at zero shear rate of 800 poise.

The solution was introduced into a stainless steel pressure vessel equipped with a millipore filter and a spinning nozzle with a sink of 75 micron diameter. The fiber was extruded under nitrogen

pressure and wound up at a pick-up speed of 120 m/min on a drum which was 3 meters under lowering. Fiber-

the diameter of the drum was 3 microns.

The filter on the drum was recycled on another drum after passing through a tubular furnace at 800°C for approximately 30 seconds at this temperature. The speed of drum number two was adjusted to approx

25% less than for the first, so that the fibers would shrink. Fiber spools from drum number two were heated overnight

in an oven at 750°C. The product was a white glassy fiber with a diameter in the range of 2 to 2.5 microns. Tensile tests gave strengths in the range 840 to 1400 kg/can 2 and a modulus in the range I, 3 to 1.7 x 10<6> kg/cm<2>.

Example 3

50 ml of an aluminum oxychloride solution containing II, 2 wt% aluminum and 8.1 wt% chlorine, was mixed with 25 ml of a 2 wt% solution of a soluble medium molecular weight polyvinyl alcohol. 1 g of boric acid and 2 drops of acetic acid were dissolved in the mixture.

The solution was evaporated to a viscosity of 900 poise at zero shear rate and 5 micron diameter fibers were collected on a drum by extrusion under pressure through a 100 micron spinneret followed by drawing through 3 m of air at 65% relative humidity.

Fiber skeins were removed from the drum and suspended in an oven under tension. The fiber was heated to 800°C for a period of 3 hours and held at this temperature for a further 3 hours. The fibers produced were white and vitreous and had tensile strengths in the region of 1050 to 1400 kg/cm 2 . They could be woven into fabric.

Example 4

100 g of ZrOCl2.8H20 was heated with 100 ml of distilled water and 2 g of CaO and 10 g of zirconium acetate solution until the CaO was completely dissolved. 50 ml of a 2% by weight solution of cold water soluble high molecular weight polyvinyl alcohol was mixed with the prepared solution and the mixture was evaporated to a viscous syrup of viscosity 800 poise at zero shear rate.

Fibers were extruded from a spinneret and these were pulled by a recovery drum located 3 m below the spinneret sinker which had a diameter of 100 microns. Fibers of diameter 5 microns were collected on the drum which was covered

with a polyethylene film.

The polyethylene film was pulled off the drum and the fibers were removed from the film without breaking. The resulting fiber coil was suspended in an oven which was heated to 1000°C for a period of 24 hours.

The products were yellow, polycrystalline, stabilized zirconium oxide fibers which were flexible and had an average tensile strength of 1400 kg/cm 2 .

Example 5

To 50 ml of an aluminum oxychloride solution with a molar ratio A1:C1 of 1.8:1 and containing 11% by weight of aluminum was added 20 ml of a 0.5% by weight solution of a high molecular weight polyethylene oxide, 1.0 g boric acid and 20 g of MgCl2.6H20. 30 ml of water was added and the mixture stirred at 50°C until all the ingredients were dissolved. The solution was evaporated to a clear syrup with a viscosity of 700 poise at zero shear rate and fiber formed by the method described in example 4 in air with a relative humidity of 45%. Fibers with a diameter of 4 microns were spun up at a take-up speed of 150 m/min and heated under tension in an oven. The furnace was heated to 1000°C

at a rate of 100°C rise per hour.

The products were 2 to 3 micron diameter fibers containing mixed phases of magnesium spinel, aluminum borate and alumina.

Example 6

50 ml of aluminum oxychloride solution containing 11.2 wt% Al and 8.1 wt% Cl was mixed with 30 ml of a 2 wt% solution of a high molecular weight polyvinyl alcohol. The mixture was concentrated by evaporation under reduced pressure to a viscosity of 50 poise. The concentrated solution was introduced into a fiber blowing device where two high velocity air streams were introduced from each side at an angle of 30° to a stream of the solution which exited from a 25 micron wide pressurized slot. The air currents had a temperature of 35°C and a relative humidity of 40%.

A mat of very fine fibers with lengths up to 10 can and diameters rated at 1 micron was collected on a gas screen cloth. The mat was heated at 800°C for 1 hour, yielding clear, glassy fibers that were silky and flexible. .

Another mat of unburnt fibers was heated at 600°C for 15 minutes, soaked in an alcoholic ethyl silicate solution, washed with ethanol and allowed to dry. The fibers were reheated by raising the temperature to 1000°C over a period of 24 hours, yielding a flexible, silky product with improved tensile strength.

Example 7

An aqueous solution was prepared containing the following: 200 g of zirconium oxychloride solution (50% by weight ZrOCl2.8H20)

200 ml zirconium acetate solution (20% by weight Zr02)

125 ml 2% by weight polyvinyl alcohol solution

12 ml conc. HC1

8 g aluminum oxychloride solution (26% by weight A^O^) -

The solution was thoroughly mixed and all particles larger than 0.3 microns were filtered out. The solution was concentrated by removal of water at 40°C under partial vacuum until the viscosity was 4.2 poise, measured at 25°C. The solution was formed into fibers by extrusion through a series of small holes into a stream of air moving in the same direction, near the speed of sound. The air stream had a relative humidity of 90% at 25°C. The fibers produced in this stream were partially dried by another stream of dry air which mixed with the fibers approx. 1.2 m below the "spin" nozzles. The fibers were deposited on a conveyor belt which passed through an oven at 1000 C with a residence time of 5 minutes in the oven. The products were soft, white and flexible.

The zirconium oxide was in a crystalline form with an average crystallite size of 100 Å. Stereoscan electron microscope studies showed that the surface of the fibers was substantially smooth and that the average diameter was 1 micron.

The fibers were impregnated with a nickel catalyst material as follows: 10 g of zirconium oxide fibers, prepared as indicated above, were soaked in a warm (60°C) solution of nickel chloride in water (50% by weight saturated NiCl2.6H20 at 25°C) for 10 minutes. The fibers were centrifuged while they were still warm, and they

was heated at 800°C for 5 minutes.

The fibers were then heated in a 3:1, by volume, mixture of nitrogen and hydrogen at 600°C for 10 minutes to produce black fibers containing 5 wt% nickel.

Example 8

Fibers prepared as described in Example 7 were sintered at 145°C for 10 minutes to increase the density and improve the strength and stiffness of the fibers. Stereoscan electron micro-

graphs showed that the surface of the fibers was quite rough. These fibers were coated with cobalt oxide (Co^O^) by soaking in a 10

wt% solution of cobalt nitrate hydrate in methanol, followed by thorough dewatering of the fibers and heating at 450°C for 10 minutes.

The fibers thus produced were black and consisted of a coating of cobalt oxide (Co^O^) which was estimated to be approx. 1/10 micron thick on zirconia fibers. They were strong and flexible.

Example 9

Fibers prepared as indicated in Example 7 were

soaked in a 10% solution of cobalt nitrate hydrate in boiling water. The fibers were then centrifuged and heated at 500°C in air

15 minutes. The increase in weight due to the cobalt oxide, Co^O^,

which was deposited in the surface layer and on the surface of the fibers,

was approximately 5%.

Example 10

Fibers prepared as in Example 7 were heated

at 1000°C for 3 hours to remove residual chloride ion and was coated with cobalt oxide, Co^O^, as in Example 2. The activity of the catalyst was improved by removal of the chloride ion.

Example 11

Fibers which were prepared as described in example 7 and

made into a 2.54 mm thick felt, was sprayed with a 30% w/v solution of cobalt nitrate hydrate. The resulting felt was treated at 450°C in air for 30 minutes. The weight of the fibers had increased by 5% due to the formation of a coating of C0.3O4.

Example 12

Fibers prepared as described in Example 7 were soaked in dilute sulfuric acid and heated at 700°C for 5

minutes.

Example 13

Fibers prepared as described in Example 7 were soaked in a 1% by weight solution of chloroplatinic acid in dilute hydrochloric acid. The fibers were then heated at 800°C.

Example 14

Fibers were made as described in Example 7, except

assumption that the following recipe was used:

200 g zirconium oxychloride solution (50 wt% ZrOCl2.8H20) 230 ml zirconium acetate solution (20 wt% ZrO2^

125 ml 2% by weight polyvinyl alcohol solution 40 g aluminum oxychloride (20% w/v Al?O 3 ) containing 2.0 g H 2 SO 4 .

By burning the above mixture at 1000°C, zirconium oxide was obtained in the cubic phase which was particularly useful for "acid" catalysis -

Example 15

Fibers were made using the following fiber-forming mixture: 200 g zirconium oxychloride solution (50 wt% Zr0Cl2.8H20) 230 ml zirconium acetate solution (20 wt% Zr02^

125 ml 2% by weight polyvinyl alcohol solution

24 g of NiCl2.6H20

5.8 g of CuCl 2 . 2 H 2 O

The solution was filtered, evaporated to viscosity 4.0 poise, "blown" into fibers and heated at 800°C for 20 minutes. The fibers were further heated in a 3:1, by volume, mixture of nitrogen and hydrogen at 600°C for 15 minutes to produce a highly active catalytic fiber.

Example 16

Fibers were prepared from the following fiber-forming mixture as described in Example 15: 200 g basic zirconium nitrate solution (20 wt% z^O2) 230 ml basic zirconium acetate solution (20 wt% ZrO2) 150 ml 2 wt% polyvinyl alcohol solution 20 g Co(N03)2.6 H 2 O The prepared fibers were heated at 450 C for 30 minutes and produced a fiber catalyst.

Example 17

A solution of suitable viscosity for spinning was prepared by dissolving together the following components in a solution of commercial zirconium acetate:

50 g of ZrOCl2.8H2O

115 ml zirconium acetate solution (22% Zr02)

1.25 g polyvinyl alcohol - medium molecular weight.

The solution was "blown" into fibers as described in Example 7, and the fibers thus formed were heated at 1000°C for 10 minutes, yielding strong, flexible, zirconium oxide fibers with an average diameter of 1 micron.

The fibers were coated by spraying with a 5% by weight solution of Ni(NO^)2•6H2O in methanol, followed by heating at 800°C. The weight gain of the fibers due to the nickel oxide coating was 5%.

Example 18

A solution was prepared from a film-forming grade polyvinyl alcohol and had the following composition: 200 g zirconium oxychloride solution (50 wt% ZrOCl2.8H20) 250 ml zirconium acetate solution (20% ZrO2 commercial grade) 150 ml 2 wt% low molecular weight polyvinyl alcohol solution 12 ml conc. . HCl

8 g aluminum oxychloride solution (26% by weight Al-^O^) .

The solution was filtered to remove all particles larger than 0.5 micron and was evaporated to a viscosity of 4 poise under partial vacuum at 40°C. The solution was "blown" into fibers with high velocity air at 30°C and relative humidity 85%. The fibers were heated at 1000°C for 10 minutes to produce a fiber catalyst.

Example 19

A solution was prepared with the following components: 100 g aluminum oxychloride solution (25% by weight Al203)

10.4 g of zirconium acetate solution (22% by weight Zj:^ 2^

64 g 2% by weight solution of polyvinyl alcohol.

The mixture was concentrated by evaporation to a viscosity of 10 poise and sprayed through a 250 micron hole into a high velocity air stream to obtain fibers with an average diameter of 4 microns. The fibers were long and silky with very little grain content.

The fibers were dried at 100°C for 10 minutes, at 200°C for 1/2 hour and finally fired at 520°C for 1 hour. The product, which had the form of a woolly mat, was soft and silky

touch.

Example 20

A solution suitable for the production of a yttrium-stabilized zirconium oxide fiber with high-temperature resistance, particularly useful for thermal insulation, was prepared from:

500 g zirconium acetate solution (22 wt% Zr02)

220 ml 1% by weight polyethylene oxide solution

12.8 g of yttrium chloride hydrate

2 ml of concentrated hydrochloric acid.

The solution was reduced on a rotary vacuum evaporator to a viscosity of 15 poise at 20°C and transferred to a vessel equipped with a spin nozzle with a hole of 0.0254 mm diameter.

A high velocity air jet exiting through slits on either side of the above hole and converging at an angle of 30° served to draw down a stream of liquid from the hole into substantially grain-free fibers having an average diameter of 1.5 microns .

The fibers were dried at 200°C for 1/2 hour and fired at 1000°C for 1/2 hour so that fibers with an average diameter of 1 micron were obtained.

Example 21

A precursor solution suitable for the production of continuous zirconium oxide fibers was prepared from the following ingredients:

76 ml commercial zirconium acetate solution (22 wt% ZrO2)

1 g of yttrium oxide, dissolved in 16 ml of concentrated HCl

15 ml 1% by weight solution of polyethylene oxide.

The solution was evaporated on a rotary vacuum evaporator to give a viscous liquid with a viscosity of 250 poise, measured at 25°C.

The solution was introduced into a bomb that was equipped with

a spinning die with a hole of 100 microns and extruded under nitrogen pressure into air with a relative humidity of 70%.

The fibers were pulled onto a 61 cm diameter drum coated with polyethylene film and collected at a speed of 305 m/min.

The fiber reel was removed from the drum and fed into

a drying oven at 200°C for 10 minutes and then heated at 1000°C for 10 minutes to give strong, flexible, white fibers with an average diameter of 6 microns. X-ray crystallographic results showed that the zirconium oxide was in the tetragonal phase.

Example 22

A solution suitable for the production of zirconium oxide fibers was prepared by dissolving the following ingredients in 115 ml of a solution of commercial zirconium acetate (22% by weight Zr02): Crystalline yttrium chloride prepared from 3.2 g of pure yttrium oxide 50 g of zirconium oxychloride (ZrOCl2 • 81^0)

3.0 g medium molecular weight polyvinyl alcohol

The solution was diluted with 4 ml of water and then gave a viscosity suitable for blow spinning. After filtration, this was extruded through a 200 micron hole into a high velocity air jet and produced fibers with an average diameter of 2 microns.

The fibers were collected as a mat on a metal cloth and, after drying at 200°C, were burned at 1000°C so that a soft, white and flexible product was obtained.

Example 23

Zirconia fibers containing cobalt were prepared from a chloride-free system as follows:

13 g cobalt nitrate hexahydrate

125 m 1% by weight solution of polyethylene oxide (molecular weight 300.OOO) 240 g zirconium acetate solution (22% by weight Zr02)

3.7 g of rare earth oxides (60% by weight v2°3) dissolved in 50 ml of 30% HNO^ and evaporated to dryness.

The above components were mixed together to give a homogeneous solution and evaporated to a viscosity of 1.3 poise at 20°C in a rotary evaporator.

Pink fibers were produced by extruding the liquid into a high velocity air jet. These were dried at 200°C for 1 hour and then acquired a purple color and were then burned at 800°C for 15 minutes, whereby grey, flexible fibers were obtained.

A portion of the fibers was reduced at 650°C in a stream of hydrogen/nitrogen to give black, flexible fibers containing cobalt metal.

Example 24

Zirconium oxide fibers as copper oxide were prepared as follows:

40 ml of 1% by weight polyethylene oxide solution

240 g zirconium acetate solution (22 wt% Zr02)

9 g of copper (II) nitrate hexahydrate

3.2 g of rare earth oxides (70% by weight yttrium oxide grade) (dissolved in as little nitric acid as possible and evaporated to dryness)

The above components were mixed together to form a solution and this was evaporated to a viscosity of 3.7 poise using a rotary vacuum evaporator. The solution was filtered and extruded as a jet into a high velocity air stream.

The pale green fibers that formed were collected on

a metal sheet and fired for 15 minutes at 800°C. The products were strong and flexible.

Example 25

Zirconium oxide fibers containing 10% alumina

and 3% cobalt, was prepared from:

100 g 50% by weight solution of ZrOCl2.8H20

115 ml zirconium acetate solution (22 wt% Zr02)

27.4 g aluminum oxychloride solution (26% by weight A^O^)

125 ml 1% by weight polyvinyl alcohol solution of high molecular weight 6.4 g cobalt chloride hexahydrate.

The solution was evaporated to viscosity 1.4 poise, measured

at 20°C, and the liquid was sprayed as a jet from a 200 micron hole into a high velocity air stream, and fibers with an average diameter of 2 microns were collected on a cloth.

The blue fibers were dried at 200°C, at which temperature

they turned green and they were then fired directly at 800°C

and then gave a product that was purplish-gray in color.

A portion of the fibers was again fired at 100°C for 1 hour

and then gave clear blue, flexible, soft fibers in the form of, a mat with strength about that of tissue paper. ■

Example 26

A solution was created consisting of:

100 g 50% by weight ZrOCl2.8H20

115 ml of zirconium acetate (22 wt% ZrO 2 ). solution 62 ml 1% by weight solution of polyethylene oxide

6.7 g of NiCl2.6H2O

27.4 g of aluminum oxychloride solution (9.3 wt% Al).

The mixture was filtered, and approximately 150 ml of the water

was removed on a rotary evaporator so that a solution with a viscosity of 3 poise was obtained.

Fibers were made by sending a jet of the solution through a 300 micron hole into a high velocity air stream.

The fibers were collected on a cloth, dried: at 200°C and

fired at 800°C for 1 hour. : . r

The fibers were colored off-white, were flexible méd: soft

grip and silky shine.

A portion of the fibers was reduced in hydrogen at 650°C and gave a black product without much loss of strength.

Example 27

Zirconium oxide fibers containing platinum, for use as an oxidation catalyst, were prepared from:

200 g zirconium oxychloride solution (50% by weight Zr0Cl2.8H20)

230 ml zirconium acetate solution (22 wt% Zr02)

250 ml 1% by weight polyvinyl alcohol solution

6.7 g of rare earth oxides (60% by weight Y20~ quality)

dissolved in 16 ml of concentrated HC1

0.29 g of chloroplatinic acid hydrate.

The solution was evaporated to viscosity 4 poise, measured at 20°C, and blown into fibers by spraying the solution into a high velocity air stream.

The fibers were dried at 100°C and fired for 1 hour at 800°C. They were white, strong and flexible.

Example 28

Fibers with the following composition were produced:

575 g airconium acetate solution (22 wt% Zr02)

253 ml 1% by weight polyethylene oxide solution

14.7 g of rare earth chlorides (60% by weight yttrium oxide quality)

18.8 g of Co(N03)2.6<H>2<0>.

The solution was evaporated to a viscosity of 6 poise and blown into fibers with an average diameter of 3 microns. These were dried for 1/2 hour at 200°C and fired at 800°C for 1 hour, yielding soft, flexible fibres.

Example 29 A solution was made with the following composition: 250 g of zirconium acetate solution (22% by weight Zr02)

31 g aluminum oxychloride (10 wt% Al)

110 ml 1% by weight solution of polyethylene oxide

28 ml calcium chloride solution (10% by weight CaO).

The solution was evaporated on a rotary evaporator to a viscosity of 10 poise at 20°C and made into fibers by spraying into a high velocity air stream to give fibers with an average diameter of 3 microns. j The fibers were dried at 200°C for 1/2 hour and fired at 1000°C for 1 hour. The fibers were white, soft and flexible. X-ray analysis showed that the zirconium oxide was in the cubic phase.

Example 30

Fibers with the following composition were made:

250 g zirconium acetate solution (22 wt% Zr02)

28 ml calcium chloride solution (10% by weight CaO)

110 ml polyethylene oxide solution (1% by weight)

32 g aluminum oxychloride solution (10 wt% Al)

7 g cobalt nitrate hydrate.

The solution was evaporated on a rotary evaporator to a viscosity of 20 poise at 20°C and allowed to stand for 24 hours. A very fine suspension had then formed in the solution, the viscosity of which had reached 50 poise.

The solution was made into fibers by extrusion at a pressure of 0.7 kg/cm 2 through a 250 micron hole into high velocity air streams converging from two slits each forming an angle of 30° with the liquid jet.

The fibers having an average diameter of 3 microns were collected on a metal cloth, dried at 200°C and calcined at 800°C for 30 minutes, followed by 30 minutes at 1000°C. The products were sky blue, strong and flexible.

Example 31

Fibers containing bismuth and molybdenum oxides were prepared from the following:

3.1 g bismuth nitrate

2.4 g of ammonium molybdate

100 g zirconium oxychloride solution (20% by weight Zr02)

115 ml zirconium acetate solution (22 wt% Zr02)

125 ml polyvinyl alcohol solution (1% by weight)

30 g aluminum oxychloride solution (10 wt% Al)

5 ml of concentrated hydrochloric acid.

The homogeneous solution was evaporated to viscosity

6 poise (20°C) and fibers were formed by injecting loose- .

ning through a 300 micron hole into a converging air stream of high velocity. The fibers were dried at 200°C and fired for 10 minutes at 800°C, so that a pale yellow product with an average diameter of 6 microns was obtained.

Example 32

A solution was made by mixing 47 parts by weight of aluminum chlorophosphate hydrate with 53 parts by weight of a 1% by weight aqueous

in

solution of polyethylene oxide with a molecular weight of 300,000. The solution had the following composition:

The mixture was slightly cloudy and yielded to filtration

a clear solution of viscosity 9.4 poise at 20°C. The solution was injected through nine triangular holes, each with a height of 0.254 mm and a baseline of 0.508 mm, into a high velocity air stream saturated with water at 0.4 kg/cm 2 and 16°C. Fibers of 3 to 4 microns in diameter were produced, and after firing for 1 hour at 200°C and 2 hours at 500°C, these gave a stable, airy mat.

The air flow was projected from two slits each 0.127 to 0.203 mm by 25.4 mm, 1.02 mm apart, entering at an angle of 60° and located on either side of the array of holes. The air flow rate was 70 1/25.4 mm under atmospheric conditions.

Example 33

A solution was made by mixing 45 parts by weight of aluminum chlorophosphate hydrate and 55 parts by weight of the 2% by weight polyethylene oxide solution. Filtration was unnecessary and the viscosity of the solution was found to be 1.6 poise at 20°C.

Fibers 1 to 2 microns in diameter and containing some grain were formed when the solution was sprayed through a 0.127 mm jet into a high velocity dry air stream.

Example 34

Aluminum fibers containing boric acid were made with the following composition:

50 ml aluminum oxychloride solution (10 wt% Al)

86 ml boric acid solution (2% by weight)

0.6 g phosphoric acid (100%)

13.4 ml colloidal silicic acid (33% by weight SiO2)

8 drops of glacial acetic acid

5 ml polyacrylamide solution (1% by weight).

The solution was filtered through a glass microfiber filter and then through a fine micron filter.

The solution was evaporated at 40°C with a rotary vacuum evaporator until vitreous fibers could be pulled from the surface with a spatula.

The solution was deaerated by leaving it under vacuum

a closed vessel for 15 hours.

The solution, which had a viscosity of 800 poise at 25°C at zero shear rate, was extruded through a 100 micron spin die using a pressure of 35 kg/cm 2 into 60% relative humidity air. The fibers were wound up on a drum at a speed of 60 m/min.

The fibers were removed from the drum, dried at 100°C and heated in an oven to 700°C. They were clear and glassy with a diameter of 10 microns.

Example 35

An acid cracking catalyst was prepared as follows: A sample of zirconium oxychloride was dissolved in a 1:1 mixture of HCl and water and recrystallized to reduce the level of sodium impurities. The crystals were redissolved in water and dialyzed against a 20% by weight solution of acetic acid until the pH value was approximately 2, whereby the chloride content was reduced.

Sufficient polyethylene oxide solution (molecular weight 300,000) and aluminum sulfate solution were added to give 1 wt.% polymer and 12 wt.% A₂O₂, respectively, based on the ZrO₂ content of the solution.

The solution was evaporated to a viscosity of 10 poise and sprayed through a series of 0.38 mm diameter holes at the point of convergence of high-velocity air streams emerging from two 60° mutual slits.

The liquid jets were weakened and partially dried by the air currents so that essentially grain-free fibers with an average diameter of 3 microns were obtained. The fibers were collected on a cloth.

The fibers were dried at 200°C and calcined for 30 minutes at 800°C, and white, soft, flexible fibers were then obtained.

A 1 g sample was placed in a catalytic reactor tube, and a stream of cumene vapor was passed over the catalyst at 450°C and with a weight per hour space velocity in 5 hours<->^. Analysis of the product showed that cumene cracking had taken place and that it was

5 volume% benzene in the product.

Analysis of the zirconium oxide fibers determined that it was

12% by weight aluminum oxide in the fibres. The level of sodium contamination was 0.1% by weight.

Example 36

1.067 g of a fiber prepared as described in Example 24 was pushed firmly into a Pyrex reactor tube of 1.5 cm internal diameter. Nitrogen, together with ethylene, oxygen and hydrogen chloride, could be passed through the catalyst layer at temperatures up to 350°C. The temperature in the catalyst was measured directly using a thermocouple.

The catalyst was initially treated in a stream

of HC1 and nitrogen for 1 1/2 hours at 300°C. The catalyst was cooled to 200°C, and ethylene and oxygen were added to the reactor feed. The composition of the gas was:

The ethylene flow rate was 1.25 x 10 mol/min.

Samples of the gas leaving the reactor were taken for gas chromatographic analysis with regard to ethylene and chlorine-containing products.

Oxychlorination was detected at 200°C, and the main product was 1,2-dichloroethane. Ethyl chloride was also detected. The amounts of each component were small, corresponding to conversions of 0.34% and 0.11% of the ethylene respectively.

Conversions are defined here as (number of moles of given compound produced per unit time) x 100, divided by (number of moles of ethylene passing through the reactor per unit time).

As the temperature increased, the selectivity of the reaction towards 1,2-dichloroethane, the desired product, reached a fixed value of approx. 90%. (The selectivity is defined as (number of moles of 1,2-dichloroethane produced per unit time) x 100, divided by (total number of moles of all compounds produced per unit time)). At 300°C and above vinyl chloride was detected, while at 350°C small amounts of cis- and trans-dichloroethylene were found.

Ethylene conversions and the reaction selectivity are detailed in the following table:

Example 37

1.47 g of a catalyst comprising 0.3 wt% platinum

in zirconium oxide fiber (prepared as described in Example 27) was packed into a silicon oxide reactor with an internal diameter of 2.5 cm and with a thermocouple pocket of diameter 0.8 cm

3

along its axis. The catalyst occupied a volume of 11 cm.

A gas mixture containing 1.27% by volume of carbon monoxide and 1.32% by volume of oxygen in nitrogen was passed over the catalyst at a space velocity of 23,200 hr. The concentrations of carbon monoxide, carbon dioxide and oxygen in the outlet stream from the reactor were determined. The catalyst "ignited" at 300°C, and at 460°C there was 97% conversion of carbon monoxide to carbon dioxide.

Under the test conditions, the non-catalyzed homogeneous oxidation of carbon monoxide to carbon dioxide does not become noticeable until temperatures reach above 830°C.

Example 38

Catalytic zirconia fibers with a content of 3% cobalt and 1% copper were made from:

115 ml zirconium acetate solution (22% Zr02)

2.2 g 60% yttrium oxide grade of rare earth oxides,

dissolved in 5 ml concentrated HNO^ and heated to dryness 65 ml 1% solution of polyethylene oxide

1.26 g Cu(NO 3 ) 2.3H 2 O

4.9 g Co(NO 3 ) 2.6H 2 O

The solution was filtered to remove particles larger than 0.3 microns and evaporated to a viscosity of 2.8 poise.

The solution was placed in a vessel with a wedge-shaped head having 250 micron holes in a row. On each side of these holes air flowed out from 250 micron wide slits parallel to the row of holes and which converged at an angle of 30° to the liquid jets from the holes. Fibers formed from the liquid that flowed out without any additional pressure being applied, using diluting air at a pressure of 0.7 kg/cm, measured in the reservoir above the air gaps. The diluting air was passed through a packed, humidifying column containing water of 23°C.

The fibers were collected on a cloth in the form of a mat, approx.

1.2 m below the spinning unit.

The fibers were dried at 200°C and fired at 800°C for 1/2 hour. Some of these fibers were reduced in a stream of H2/N2

at 650°C. The average diameter was 3 microns.

Example 39

Tetragonal zirconia fibers containing 2 wt% aluminum in oxide form to control the grain strength of the zirconia were prepared as follows:

100 g zirconium oxychloride solution (50% by weight Zr0Clo.8H„0)

115 ml zirconium acetate solution (22 wt% Zr02)

125 ml polyvinyl alcohol solution (1% by weight)

8 g aluminum oxychloride solution (26% by weight A^O^)

3 g of yttrium oxide

8 ml of concentrated hydrochloric acid

The solution was evaporated to a viscosity of 2 poise and fibers with an average diameter of 1 to 2 microns were collected using a "blow" device. The fibers were dried at 100°C

and then fired at 1000°C for 2 hours. X-ray analysis showed that the fibers contained tetragonal zirconium oxide with a crystallite size estimated at 265 Å.

A sample of these fibers was heated to 1450°C i

15 minutes, after which the fibers became noticeably stiffer, but were still strong and flexible.

Example 40

Zirconium oxide fibers containing 3% by weight cobalt and 1% manganese, with approximately 7% rare earth oxides as phase stabilizer, were prepared from the following:

250 g zirconium acetate solution (22 wt% Zr02)

110 ml 1% by weight solution of polyethylene oxide

9.5 g rare earth chlorides (50% by weight yttrium grade) 8.1 g cobalt nitrate hydrate

1 g manganese(II) chloride hydrate

The solution was evaporated to a viscosity of 10 poise and extruded through 0.38 mm diameter holes using 0.21

kg/cm 2 absolute pressure, into a high-velocity air stream which issued from converging slits at an angle of 30° to the liquid jets. The pressure of the thinning air was 0.7 kg/cm.

The fibers were dried at 200°C, fired at 800°C for 1/2

hour and reduced in a hydrogen/nitrogen atmosphere at 700°C

so that a scjrt fiber mat was obtained. Rolled mats of these fibers were prepared for catalytic oxidation reactions.

Example 41

0.76 g of a catalyst comprising 3% by weight of cobalt,

1 wt% copper, 7 wt% rare earth oxides in zirconium

oxide fiber (prepared as described in Example 38) was packed into a silicon oxide reactor with an internal diameter of 2.5 cm.

A thermocouple pocket of 0.8 cm diameter ran along the axis of the tube.

ter. The catalyst occupied a volume of 17 cm 2 .

A gas mixture comprising 1.23 vol% carbon monoxide

and 1.34 vol% oxygen in nitrogen was passed over the catalyst at a space velocity of 15,000 hr<-1>. The catalyst "ignited" at 250°C, and at 375°C there was a 75% conversion of carbon monoxide to carbon dioxide.

Claims (25)

1. Process for the production of inorganic fibers comprising fiber formation by blowing a mixture with a viscosity greater than 1 poise and comprising a solvent and a metal compound selected from the chlorides, sulphates, acetates, formates, hydroxides and nitrates of aluminium, iron, zirconium, titanium, beryllium, chromium, magnesium, thorium, uranium, yttrium, nickel, vanadium, manganese, molybdenum, tungsten and cobalt, as well as 0, 1-10% by weight, based on the total weight of the mixture, of an organic polymer having a molecular weight in the range 10^-10^, both the metal compound and the organic polymer being soluble in the said solvent, the weight proportion of the organic polymer being smaller than 10% of the weight proportion of the metal compound, removal of at least part of the solvent from the produced fibers and heating of the fibers to split the metal compound and/or the organic polymer, characterized in that the fiber formation is carried out by extruding the mixture through one or more openings into at least one gas stream that has a high-velocity component in the extrusion direction of the extruded mixture, optionally using a fiber-forming mixture containing a catalyst material or a precursor thereof. 2. Method as stated in claim 1, characterized in that a water-soluble metal compound is used. 3. Method as specified in any of the preceding claims, characterized in that water is used as the solvent, and as the metal compound a metal salt or a basic metal salt which gives a viscous solution or sol in water, and that a water-soluble organic polymer is used. 4. Method as stated in claim 1, characterized in that a metal salt which can form a refractory oxide is used as the metal compound. 5. Method as stated in any of the preceding claims, characterized in that aluminum oxychloride, basic aluminum acetate or formate, zirconium oxychloride, basic zirconium acetate, basic zirconium nitrate or basic zirconium formate are used as metal compounds. 6. Method as stated in any of the preceding claims, characterized in that a straight-chain polyhydroxylated polymer is used as organic polymer. 7. Method as stated in any one of claims 1 to 5, characterized in that polyvinyl alcohol or partially hydrolyzed polyvinyl acetate is used as organic polymer. 8. Method as stated in any one of claims 1 to 5, characterized in that polyethylene oxide or polyethylene glycol is used as organic polymer. 9. Method as stated in claim 7, characterized in that a polyvinyl alcohol or a partially hydrolyzed polyvinyl acetate is used which has a medium or high molecular weight. 10. Method as stated in claim 8, characterized in that a polyethylene oxide with a molecular weight of 10<4->10<6> is used. 11. Method as stated in any of the preceding claims, characterized in that the fiber-forming mixture is used with a viscosity in the range 1-100 poise. 12. Method as stated in any of the preceding claims, characterized in that an opening with at least one dimension of 50-500 microns is used. 13. Method as stated in any of the preceding claims, characterized in that air is used as gas stream. 14. Method as stated in claim 13, characterized in that air at ambient temperature is used. 15. Method as stated in any of the preceding claims, characterized in that two gas streams converge at or near the point where the mixture is extruded from the opening. 16. Method as stated in claim 15, characterized in that an angle between the converging gas streams of from 30 to 60° is used. 17. Method as stated in any of the preceding claims, characterized in that the gas comprising the gas stream is pre-mixed with vapor of the solvent in the fiber-forming mixture. 18. Method as specified in claim 13 or 14, characterized in that air with a relative humidity above 80% is used. 19. Method as stated in any of the preceding claims, characterized in that a gas flow with a speed of 60-450 m/sec is used. 20. Method as stated in any of the preceding claims, characterized in that a fiber-forming mixture is concentrated* before fiber formation. 21. Method as stated in any of the preceding claims, characterized in that the fiber-forming mixture is deaerated before the fiber formation. 22. Method as stated in any of the preceding claims, characterized in that the fibers are heated to a temperature of 100-1000°C. 23. Method as stated in claim 22, characterized in that a fiber comprising a refractory oxide is sintered by further heating. 24. Method as stated in claim 23, characterized in that the sintering is carried out at a temperature of from 500 to 2000°C. 25. Method as stated in any one of claims 22 to 24, characterized in that the heating is carried out in successive steps with increasing temperature.