US2148342A - Catalytic body - Google Patents

Description

Patented Feb. 21, 1939 CATALYTIC BODY Alice M. Fairchild, Chicago, Ill., assignor to Sears, Roebuck & 00., Chicago, 111., a corporation of New York No Drawing.

Application July 22, 1937.

Serial No. 155,003

. 6 Claims. (01. 23-233) Another object is to provide an improved porous ceramic catalytic body having considerable tensile strength and a low co-efficient of expansion through a wide temperaturerange in order that it may render long service at high temperatures without breaking down or disintegrating, and which avoids the use of silica'or feldspar as components of the body structure.

A further object of the invention is to pro vide an improved catalytic body adapted for use with hydrocarbons which will not be poisoned by foreign substances in the hydrocarbons or carbonized through long continued use.

Other objects and advantages will be apparent from the following description and claims.

A catalytic body embodying the concepts of the present invention comprises in part a ceramic structure which is composed essentially of one or more lanthanum compounds such as lanthanum oxide, lanthanum hydrate, lanthanum sulphate and lanthanum phosphate, together with This invention relates to catalytic bodies and more particularly to a refractory ceramic catalytic body for rectifying or converting liquid hydrocarbon fuels having relatively high boiling constituents into gaseous hydrocarbon fuels having relatively low boiling constituents.

Catalytic structures embodying the present invention are particularly adapted for use in connection with burners, stoves, lamps, and internal 1o combustion engines, and may be employed in any suitable gaseous fuel generator such as is disclosed in the following United States patents: Patent No. 1,902,630 to Fairchild, issued March 21, 1933; Patent No. 2,006,367 to Rathburn, issued July 2, 1935, and Patent No. 2,044,544 to Rathburn, issued June 16, 1936.

The present invention is concerned primarily with the composition of the catalytic body, and not with any particular type of gaseous fuel genorator which may be employed.

An object of the present invention is to provide a new and improved catalytic body for converting liquid hydrocarbon fuels, such as gasoline, kerosene, and fuel oil, having high boiling constituents, directly into a fixed combustible gaseous fuel having low boiling constituents.

A further object of the present invention is to provide a new and improved catalytic bo'dy adapted to combine thermolysis, catalysis, and

- radioactivity for effecting a scission of highboiling hydrocarbon molecules into the molecular constituents, and a synthesis of the molecular constituents into low-boiling hydrocarbon molecules.

Another object of the invention is to provide an improved catalytic body for converting liquid hydrocarbon fuels into gaseous hydrocarbon fuels, which is adapted to operate at relatively high temperatures in contact with relatively cold 4 liquid fuels for effecting a cracking action on the liquid fuels as a part of the conversion process, and which' will develop and maintain the relatively high operating temperatures by the fiameless combustion or oxidation of a part of the fuels without igniting either the liquid fuels or the gaseousfuels.

A further object is to provide an improved catalytic body for rectifying or converting liquid hydrocarbons having relatively high boiling con- 0 stituents into combustible gaseous'hydrocarbons having relatively low boiling constituents, and for more completely ionizing the low boiling gaseous constituents as a part of the conversion process for providing a gaseous hydrocarbon fuel more emcient in combustion.

a suitable binding' clay.

satisfactory results.

A ceramic structure formed from lanthanum oxide, magnesium oxide, 2. suitable refractory clay such as kaolin, a flux, and a fugitive such as carbon, has been found satisfactory.

The following example represents a mixture of the materials employed for producing a ceramic structure which has been found to be particularly suitable:

After the raw materials have been weighed, the lanthanum oxide, magnesium oxide, kaolin, fiux, and a sufficient amount of water are placed in a suitable mixer such as a ball mill andmixed thoroughly for providing a homogeneous mixture, after which the granulated coke is added and the mixing action continued until the coke particles are dispersed uniformly throughout the mixture.

After the mixture is removed from the mixer, the surplus water is drained ofi and the mixture is formed into the desired shape by any suitable means such as moulding, pugging, or die-forming, for providing the desired structure.

The structureis allowed to dry thoroughly and is then heat-treated by being fired or baked in a suitable furnace or kiln at approximately pyrometic cone equivalent 14 for a length of time sufiicient to provide the ceramic structure desired. The time required for the heat-treatment is determined largely by the size and shape of the structure treated.

During the firing operation the coke particles dispersed throughout the structure are burned out and thereby provide a porous ceramic struc ture having a porosity of approximately 15%.

It will be noted that a flux is employed as an ingredient of the mixture for providing the ceramic structure in order that the other ingredients may be more easily and more' perfectly blended during the heat treatment of the structure.

Any suitable flux may be utilized which will accomplish the desired results, and therefore it is not intended that the invention be limited to any particular flux which may be found to be satisfactory. A flux which has been found to be particularly suitable, however, and also, which is believed to be novel, utilizes a lanthanum compound having characteristics particularly desirable in a catalytic body to which the present invention is directed, namely, the emission of activating rays at relatively high temperatures, and which supplements the other lanthanum compounds in the structure.

The following example represents the composition of afiux which may be utilized as a component of the mixture for providing the ceramic structure:

Lanthanum phosphate (LaP04) Magnesium phosphate (Mga(PO 4) 2) Calcium phosphate (Ca3(PO4)z) The above phosphates of lanthanum, magnesium, and calcium are orthophosphates which are very refractory and this particularly desirable property, together with other desirable characteristics of the compounds, is imparted to the structure of which'they become a part.

The phosphates may be prepared from the following ingredients.

Parts by weight Lanthanum oxide (LazOa) 40 Magnesium oxide (MgO) Calcium carbonate (CaCOa) 8 After the ingredients have been weighed they are mixed or blended and then converted to phosphates by the addition of phosphoric acid, HaPO4.

The mixture of phosphates is dried and then fused into a homogeneous mass which is permitted to cool, and, when cold, is ground into a fine powder which will pass a screen of approximately 200 mesh.

The phosphate ingredients of the flux may be prepared in any conventional manner, which is found to be convenient, the above example being given only for the purpose of making the disclosure complete.

It will be understood also that any suitable lanthanum compounds may be utilized as ingredients of the flux as well as the hereinbefore mentioned composition for providing the structure.

A body prepared in accordance with the principles of the present invention, as .disclosed thus far in the preceding description, provides a porous rei'ractory'ceramic" structure having a very low .co-eflicient of expansion and a relatively high tensile strength, which enables it to withstandsudden temperature variations, to operate I over a wide temperaturerange, and at continuous operating temperatures of approximately 2000- F. to 2200 F. while in contact with relatively cold liquid fuels'without causing the structure to crack or disintegrate, and which will have the porosity required to operate with the utmost efliciency, as the emciency of the catalyst is dependent on the surface area of the catalytic-body which is employed. I

The porous lanthanum ceramic structure, after having been heat treated and permitted to cool, is impregnated with an aqueous solution of salts of the desired metals which include lanthanum,

and members of the platinum group, and may include other metals such as lithium, magnesium,

and chromium. v

The salts of the above metals which have been found to be most satisfactory are the chlorides. and the following example represents a solution of the metallic chlorides which has been found to be particularly suitable for providing a body having the desired catalytic and activating characteristics.

Grams r of H20 Lanthanum chloride (LaCla) 25.00 Platinum chloride (PtClz) 15.00 Palladium chloride (PdClz) 2.00 Lithium chloride (LiCl) 2.00 Magnesium chloride (MgCh) 2.00 Chromium chloride (CrClz) 2.00

to the metallic lanthanum particles and the remaining lanthanum oxide is disposed as an isolating or insulating medium between the metal particles or compounds and prevents them from uniting or combining into a mass or masses of metal.

Other halogen compounds of the metals, as well as other salts of the metals, such as sulphates or phosphates, may be used for providingthe impregnating solution, and, therefore, it is not desired that the invention be confined to chloride salts of the metals as used in the above example.

A catalytic body produced in accordance with the preceding description has been found to have an effectiveness and efiiciency in quickly and continuously converting high-boiling hydrocarbons into low-boiling hydrocarbons, far beyond expectations.

In actual practice the catalytic body is first heated to an initial starting temperature of approximately 150 F. to 200 F. after which the liquid fuel is turned on, and the body begins to act on the ,fuel for generating its own heat and quickly develops and maintains a relatively high working temperature of approximately 2900 F. to2200 F. by the flameless oxidations or combustion of a part of the fuel without igniting the fuel. At the essential working temperatures the catalytic body glows with radiant heat energy and provides a thermal-catalytic action for rearranging the molecular structure of the hydrocarbons.

It will 1w readily understood, of course, that the relative proportions of the constituents of the body may be varied for controlling the thermal, catalytic, and thermionic activity of the body, and thereby controlling the quality or character of the gaseous fuel produced from, the liquid hydrocarbons, as the efilciency and effectiveness of the catalytic body is dependent on the stability of the hydrocarbon acted on and the specificity of the catalytic body for the particular reaction.

It is believed that the reactions and interrelated functions of the constituents of the catalytic body and the hydrocarbons are very complex, and that many unstable and transitory compounds result from reactions which take place.

While it is possible that the reactions which are hereinafter describedare not exactly those which take place, it has been determined from experimentation that the reactions which take place are generally along the lines herein presented. r

When the body is cold 9. large proportion of the metals are in the form of compounds such as oxides. When the body is heated to the initial starting temperature and the liquid hydrocarbon fuei'contacts the body, the fuel is partly decomposed into the constituent carbon and hydrogen atoms.

Lithium reduces from the oxide to the metal at the very low temperature of approximately 200 F. and at this temperature hydrogen from the fuel combines with the released oxygen by flameless combustion which increases the temperature of the body. The reduction of the lithium oxide to the metal is followed by the reduction of the palladium, platinum, lanthanum and magnesium oxides to the metals as the temperatures of the body increases, and each of these reducing processes successively increases the temperature of the body to the point necessary for carrying out the next succeeding reducing process. The great aiiinity of palladium and lanthanum for hydrogen attracts a sufficient amount of hydrogen within the body for carrying on the reactions between the other constituents and the hydrogen, and this activity of the palladium and lanthanum is believed to be accelerated by the radiations from the lanthanum which extend in range from the ultra-violet rays well into the infra-red rays at the higher temperatures. Thus it will be noted that the activity of the palladium, and consequently, the activity of the other constituents, may be controlled through the lanthanum compounds.

The radiation activity of the lanthanum, however, is controlled by the presence of the magnesium and its compounds, and can therefore be accelerated or retarded by changing the relative proportions of these constituents. The lithium is also believed to co-act with the platinum, palladium and chromium, to permit the utilization of the catalytic properties of the elements, and to prevent the ignition of the fuel which would otherwise result from the use of these elements at the high working temperature required.

As an example, the metals of the platinum group would normally ignite the fuel at a temperature of approximately 1500 F but is prevented from doing so in the present catalytic body by the inhibiting tendencies of the lanthanum and magnesium constituents of the body.

When the catalytic body is operating at temperature in excess of the initial working temperature, the lanthanum, platinum group and chromium constituents appear to continuously undergo an alternate process of oxidation and reduction, depending on the temperature of the body which may aid in explaining the oxidation of a part of the hydrogen from the fuel for maintaining the working temperature of the body.

Thus it will be noted that a body is provided which will develop and maintain a high coemcient of radiation without igniting the fuel.

The relatively high temperatures ofthe body accompanied by dehydrogenation of the fuel as a result of the flameless oxidation for providing the high temperatures, together with the catalytic activity of the components of the y, and

the radiations from the lanthanum components, all combine to decompose or rupture the bonds of the molecules of the higher hydrocarbons and to rearrange the molecular constituents into molecules of the lower hydrocarbons whose empirical formula is that of the CH group.

The rearrangement of the molecular constitucuts into molecules of the lower hydrocarbons appears to be directed and controlled by the radiations and thermionic emission characteristic of the lanthanum components, and the lower hydrocarbons so formed have been found to belong principally to methane series of compounds.

When the liquid hydrocarbon fuels are mixed with the proper amount of air prior .to being acted on by the catalytic body, the resulting gaseous fuel may also contain a minor proportion of carbon monoxide.

The thermionic emission of the lanthanum components in the catalytic body is also believed to cause a greater ionization of the low boiling hydrocarbons of the gaseous fuel than would otherwise result, and therefore provides a gaseous fuel which is more eflicient in combustion.

The process of rectification may be controlled, and the relative proportions of the lower boiling hydrocarbon constituents in the gaseous fuel may be varied by changing the relative proportions of the lanthanum components in the catalytic body.

A refractory ceramic catalytic body prepared in accordance with the preceding disclosure has the property of rectifying liquid hydrocarbon fuels into fixed, permanent, gaseous hydrocarbon fuels, and exerts the maximum activity with the minimum consumption of thermal energy.

Thus it will be noted that a catalytic body is provided which is particularly adapted for use in suitable gaseous fuel generators for the purpose intended as herein set forth.

I claim:

1. A catalyst comprising a porous ceramic body containing dispersed therethrough a lanthanum comp0nent and an activity inducing agent consisting of a component selected from the group consisting of elements and compounds of the platinum group of metals.

2. A catalyst comprising a porous ceramic body containing dispersed therethrough a lanthanum component, a, component selected from the group consisting of elements and compounds of the platinum group of metals as a primary activity-inducing agent, and a secondary activity-inducing agent consisting of a component selected from the group consisting of lithium,

v magnesium, chromium and their compounds.

3. A catalyst for the treatment of hydrocarbons, comprising a porous ceramic body containing dispersed therethrough a lanthanum component, a component selected from the group consisting of elements and compounds of the platinum group of metals as a primary activitylnducing agent, and a secondary activity-inducing agent consisting of acomponent selected from the group consisting of lithium, magnesium, chromium and their compounds, said activityinducing agents being the heat-treated reduction products of an aqueous impregnating solutlon. I

taining dispersed therethrough a lanthanum component, a component selected from the group consisting of elements and compounds of the platinum group of metals as a primary activityinducing agent, and a secondary activity-inducing agent consisting of a component'selected from the group consisting of lithium, 'magnesium chromium and their compounds, said activity- 4. A catalyst for the treatment of hydrocar- 'bons, comprising a. porous ceramic body coninducing agents being the heat-treated reduction products of an aqueous chloride impregnato ing solution.

5. A catalyst comprising a porous ceramic body containing dispersed therethrough a lanthanum component, a component selected from the group consisting of elements and compounds of the platinum group of metals as a primaryactivityinducing agent, and a secondary activity-induc ing agent comprising a plurality of components selected from the group consisting of lithium,