CA1066765A - Substance and device for the absorption of catalyst poisoning gases out of the oxyhydrogen gas mixture - Google Patents

Abstract

ABSTRACT
A substance, a method of producing it, and a device for using the substance in the absorption of catalyst poisoning gases out of the oxy-hydrogen gas mixture produced by lead-acid storage batteries, the substance effecting the oxidation of the unstable catalyst poisoning gases SbH3 and AsH3 to produce hydrolysis-resistant intermetallic compounds. As absorbing substances are usable heavy-metal manganites, heavy-metal oxides and cata-lytic agents. As a device, the absorbing substance ia combined with an oxygen and hydrogen recombination unit.

Description

~066765 The present invention relates to absorbing substances for the removal of catalyst poisoning gases, viæ. the compounds of hydrogen with the elements of Group V of the Periodic Table of Elements, particularly with arsenic (As) and antimony (Sb), from the oxyhydrogen mixtures ~hich are gen-erated during the operation of lead-acid storage batteries. The invention ~urther relates to methods of producing such absorbing substances, and to the application of such substances in combination with a special catalyst unit taking the place of 8 closure plug on a lead-acid storage bsttery, the purpose oP thi6 catalyst unit being to catalytically recombine the hydrogen and oxygen gases generated during the operation Or the lead-acid storage battery to obtain water which i8 returned to the battery electrolyte.
It iB known that considerable problems still exist in connection ; with the catalytic recombination of hydrogen and oxygen produced by lead-~.
~` acid 6torage batteries, as a result of the poisoning of the activ~ cataly6t material through the gaseous compounds of antimony-hydrogen and arsenic-hydrogen, the so-called catalyst poisoning gases. These catalyst poisoning gases are produced through the reaction of hydrogen with certain alloy com- -ponents of the lead used in the manufacture of lead-acid storage batteries.
Primarily for reason6 of improved quality, the lead alloy6 used for a wiae variety of lead-acid storage cells frequently contain arsenic and antimony components. These alloy components combine with hydrogen to form the volatile, rather unstable, gaseou6 compounds of antimony hydride (SbH3) and arsenic bYdride (AsH3), both being very effective as cataly~t poisoning gases~
It has been variously attempted in the past to remove these so-j~ called catalyst poisoning gases from the oxyhydrogen gas mixtures which are generated by electrical lead-acid storage batteries. For instance, one approach (United States Patent No. 3,102,059) suggests that the oxyhydrogen gases, before reaching the catalyst, are made to flow over a granular bed of alumina or of a mixture of alumina and lead-dioxide on an alumina carrier.
It is further known (United States Patent No. 3,038,954) to arrange a bed of lead-oxide on a carrier of P-luminum-oxide powder inside a battery plug in the - 1 - ~: .

,' ~low path of the gases ahead o~ the catalytic material which recombines the hydrogen and oxygen generated by the battery.
A particular shortcoming of these prior art substances is their very short span of effectiveness which can be measured in days.
The present invention suggests an absorbing sub-stance ~or the removal Or the above-mentioned catalyst poisoning gases, especially of antimony-hydride and arsenic-hydride, from the oxyhydrogen gas mixtures ~hich are gen-erated in electrical lead-acid storage batteries during their operation as well as & method o~ producing such ;
~` absorbing substances. Furthermore the invention provides for a device for the catalytic recombination o~ the oxy-hydrogen gas produced by a lead-acid storage battery to water and for returning the water to the battery electro-lyte. The device comprises in combination: a generally gastight housing arranged above the battery electrolyte and connected with the space containing the latter for gas ~ flow communication and for liquid return ~low thereto; a `
-;1 20 catalyst body mounted in the cavity of the housing, the catalyst body serving to recombine the oxygen and hydrogen gases to water; a bed o~ an abosrbing substance surrounding -the cataly~t body, the absorbing substance serving to eliminate from the oxyhydrogen gas mixture the so-called catalyst poisoning gases, e.g. antimony-hydride and arsenic-hydride which are generated together with the oxyhydroge~ `~
gases during battery operation, and means ~or containing the bed o~ absorbing substance around the catalyst body.
.:
The improved device substantially increases the duration of ` ~ 30 e~ectiveness of the catalyst.
The present invention suggests the use of heavy-~ metal manganites of one or several metals as absorbing ~ 2 :`

~066765 substances, preference bein6 given to copper manganite. In place of this preferred group of compounds, it is also pos-sible to use heavy-metal oxides for the removal of catalyst poisoning gases from the oxyhydrogen gas mixture generated by lead-&cid storage batteries~ For example, one may use the oxides of the elements iron, cobalt, nickel, tin, gal-lium, indium, and thallium, either separately or in com-bination, for a reaction with the antimony-hydride and arsenic-hydride to obtain hydrolysis-resistant arsenides and antimonides in the form of intermetallic compounds.
These heavy-metal oxides may also be employed in combina-tion with the aforementioned heavy-metal manganites to obtain 8 suitable absorbing substance.
The present invention further proposes that the absorbirg substance includes oxidic compounds of elements, either of one or several types, or as an additive to the heavy-metal oxides, these oxidic compounds being reduced in the reaction with the antimony-hydride and arsenic-hydride, under oxidation of the latter. Especially suitable for this purpose are: molybedenum trioxide (MoO3), tungsten trioxide (W03), and manganese dioxide (MnO2). Lastly, the lnvention auggests that the ab~orbing substence include ' .'' ,~ .

- 2a -~, .''.

~06676~;

oxides which are catalytically active as oxygen transfer agents, the oxides being used separately or in combination, or in addition to the heavy-metal oxides. Suitable examples of such oxygen transfer oxides are, in particular, ferric oxide (Fe203), vanadium pentoxide (V205), and chromium trioxide (Cr203). These oxygen transfer agents cause an oxidation of the antimony-hydride and arsenic-hydride, when they come in contact with these gases.
From the above, it can be seen that the various approaches to the basic solution proposed by the invention relate to different reaction mech-Qnisms which are operative in the reaction between the oxidic absorbing sub-stances, and the antimony-hydride and arsenic-hydride. Thus, the first group of oxidic compounds produces antimonides and arsenldes, while the two other groups produce oxidic compounds of antimony and arsenic. In the first case, the oxidation of the catalyst poisoning gases is obtained through the action -~ of an oxidation agent, whereas the second case involves the catalytic trans-fer of oxygen. However, it should be understood that the foregoing explana-tion of the reaction mechanisms is based upon hypothetical assumptions which were reached as a result of the research underlying the present invention.
The inventors, therefore, do not pretend that their hypotheses regarding the ~ --aforementioned reaction mechanisms are necessarily complete and correct.
~owever, it has been found that each one of the substances listed herein materially contributed to an improved de-poisoning of the oxyhydrogen gas mixture which is given off in lead-acid storage batteries during operation.
Particularly good results have been obtained with heavy-metal manganites, ` especially with copper manganite.
The pre3ent invention also suggests ways of improving the effec-tiveness of the aforementioned absorbing substances still further, by arrang-ing the substance on a carrier material, preferably an alumina gel. The car-rier itself is preferably in granular form, the grain size for use in con-~unction with conventional automobile batteries ranging between 0.1 mm and ;30 1 mm, and preferably between 0.2 mm and 0.5 mm.
The present invention further suggests a method of producing the absorbing substances mentioned earlier, the method being characterized in .
' .. ,- , . . ...

that a solution ~f a salt of the element, or elements, i8 producPd which, in its oxidic form, reacts with antimony-hydride and arsenic-hydride to create antimonide or arsenide, or their oxides, respectively, and that the carrier material is introduced into this solution at an elevated temperaeure~that following a period of interaction, the mixture is introduced into a sodium carbonate solution or the like in order to precipitate the carbonate, and that the substance is then washed, dried, and calcinated. Preferred operat-ing conditions for the method of the invention are listed in the various specific examples given further below.
Lastly, the invention suggests a novel device for the catalytic recombination of the hydrogen and oxygen gases produced during the operation a lead-acid storage battery, to obtain water and to return the latter to ; the electrolyte of the battery. This device is characterized by a generally cylindrical housing which includes a stub connection on its outside and a porous body mounted against one housing face, ad~acent to which is arranged a catalyst body, the latter being surrounded by a uniform layer of a granular . absorbing substance contained inside a sleeve surrounding the catalyst body.
~he catalyst body is preferably in the shape of a rod and retained by its ends inside flanges in opposite end faces of the housing, whereby the flanges also serve to position the gas-permeable sleeve concentrically in relation ~, .
to the catalyst rod, the annular space between the sleeve and rod containing the absorbing substance.
` The gas-permeable sleeve is preferably of a ceramic material. How-,~ ever, it may also be in the form of a cylindrical screen, for example, a ; sleeve of wire mesh.
It was found to be advantageous to arrange one mounting flange in s the hou8ing as out~ardly oriented extension, and to use a putty seal as a closure for the flange opening, the putty seal also serving to position and secure the catalyst rod, the absorbing substance, and the gas-permeable slee~e.
Further special features and advantages of the invention will ,~ become apparent from the description following below, when taken together . _ 4 _ .'" ' '' , . : . : . .. : :.. : ... . : . . .

~Q66765 with the accompanying drawing which illu~trates, by way of example, a preferred embodiment of the invention in the form of a catalytic recombina-tion device, represented in the figure as follows:
The figure of the drswing illustrates in an elevational view, partially shown in longitudinal cross-section, a device embodying the inven-tion.
Commercially available lead-acid batteries of the type 12 volts -45 amp hours with 5 positive and 6 negative plates in esch cell were used to test the novel absorbing substance of the invention. The grid of each cell plate was made of a lead alloy which contained approximately 5.5 percent antimony and 0.15 percent arsenic. Each cell was closed hermetically by mounting in its opening a recombination device of the type illustrated in the drawing. The purpose of such a device is to recombine the hydrogen and oxygen gases generated during the operation of the battery to water. The recombination device includes a catalyst consisting of acatalyst carrier i~ material, preferably palladium, the catalyst being provided in the form of a rod 1, or in some other suitable geometric form. The length of the catalyst rod 1 is several times larger than its diameter. This catalyst body is accommodated inside a housing 4 of plastic material which has a substantially ~` 20 semi-cylindrical cross_section, the bottom 3 o~ housing 4 being inclined ~ toward a downwardly extending hollow stub connection 5 through which the gas `` mixture enters into the housing and the recombined water returns to the electrolyte of the battery. One end face of housing 4 has a laterQl opening `` 6, a porous body 7 surrounded by a plastic plug 11 closing the opening 6 against the outside. The plastic plug 11 includes an inwardly oriented hol-. . .
; low flange 8 extending into the housing 4 in the direction of an opposite end face. This opposite end face of the housing includes an outwardly extending flanKe 9 in alignment with flange extension 8 of the plastic plug 11. The .~ :
catalyst rod 1 of the device extends between these two flanges 8 and 9, the opening of n ange 9 being closed after assembly by a putty seal. -The porous body 7 con~ists of a ceramlc mass which is made hydro-phoblc by a known treatment. The inside of housing 4 thus forms a convenient reaction space inside which the exothermic reaction of recombining the hydrogen and oxygen gases to water under the influence of the earlier men-tioned catalyst takes place.
In order to prevent the premature poisoning of the catalyst mate-rial, a ceramic tube 10 is arranged between the flange extension ô and flange 9 of the housing in concentric arrangement with the catalyst rod 1 so as to provide an annular space around the latter. Within this annular space be-tween tube 10 and the catalyst rod 1 is contained a granular bed of sbsorbing material 13, which thus surrounds the catalyst rod 1 in a uniform thickness.
~his bed of absorbing material 13 is preferably approximately 5 mm thick.
The aforementioned batteries were sub~ected to a test in which they were overloaded with a current of 3 amps until the catalyst failed as a result of poisoning. Whenever a battery was exhausted, the test devices would be trans~erred to new batteries. The following absorbing substances have been tested:
SubstanceEffectiveness Silicagel 3 days ~, ~
Alumina gel 9 days Various Nicrofilters max. 7 days From the above listing, it can be seen that the effectiveness span of these materials is extraordinarily short.
However, it was found that if a commercially available type of alumina gel is used as a carrier material for a heavy-metal oxide, a con-siderable improvement was achievable. The effectiveness in this case was i~ extended to 483 days. This absorbing material was produced in the ~ollowing ~ manner:
,~t Example No. 1: A solution of 2.62 moles of CuS04 5 H20 per liter was produced and into each liter of solution were introduced o.66 kg of dried alumina gel, grain size 0.2 to 0.5 mm, at 80 C temperature. Following some reaction time, the mixture was introduced into a 5-percent sodium carbonate solution at 50 C temperature, whereupon the copper carbonate was precipitated.

Following washing, drying and calcination at 350C to 400 C, the substance _ was ready for use.
A markedly greater improvement of the effectiveness span was achieved through the use of heavy-metal manganite~. Heavy-metal manganites containing for example, between 50 and 95 percent MnO2 and, for example, between 5 and 40 percent CuO, with a corresponding admixture of Co304, Ni203, and Ag20, as well as mixtures of the aforementioned oxides, when prepared on an alumina gel carrier or some other suitable carrying material, are capable of increasing the longevity of the catalyst to in excess of 550 days. An absorbing substance of this type was produced as follows:
Example No. 2: A solution of 1 50 moles per liter of MnS04 -4 H20, 1.10 moles per liter of CuS04 - 7 H20, and 0.15 moles per liter of NiS04 - 7 H20 was prepared. Into one liter of this solution, heated at 80C
temperature, were introduced o.66 kg of dried alumina gel, grain size 0.2 to 0.5 mm. Following a reaction time of 90 minutes (under occasional stirring), the mixture was introduced into 3 liters of a 5 to 10-percent solution of Na2C03 at 50C temperature, so that the corresponding combination carbonates were formed. Following a further reaction time of 30 minutes (under occa-sional stirring), the product was washed, dried and calcinated for 30 to 60 minutes at a temperature between 350 and 400C, after which the substance . , .
~- 20 was ready for use.
During the aforementioned calcination treatment, under simultaneous ~-exposure to air, the manganese and copper combination carbonates would create copper manganites. The effectiveness span of this substance was found to be 578 days.
This remarkable improvement in the span of effectiveness has been confirmed in connection with other substances which are available in oxidic form, the primary characteristics developed through these research exper iments and tests on absorbing substances capable of removing the hydrogen -~
compounds of arsenic and antimony, elements of Group V of the Periodic Table of Elements, being the capability of forming arsenide and antimonide, re-~pectively, with the component substances of the absorbing substance, and the capability of oxidation or of oxygen transfer of the component substances in ~066765 the absorbing substance. As oxidation substances in this context shoula be understood those compounds which are reduced ~n reaction with AsH3 and SbH3.
Oxygen transfer agents, on the other hand, are compounds whose catalytic effect produces the reaction of AsH3 and SbH3 with 2 Consequently, a suitable absorbing substance may be composed Or oxides of elements which create hydrolysis-resistant arsenides and anti-monides, or respectively, oxidic compounds of arsenic and antimony. As examples for such elements may be mentioned tin, nickel, cobalt, iron, copper, silver, gallium, indium, Rnd thallium, but it should be noted that the hydrolysis-resistant arsenides and antimonides of these elements no longer possess the characteristics of a salt, but are presumably intermetallic com-pounds.
; Apart from these oxides which are suitable for use as absorbing substances, other elements in oxidic form may be used which qualify as oxida-tion agents and oxygen transfer agents, such as for example: V205, Cr203, Fe203, MoO3, and W03.
The aforementioned absorbing substances may be used separately or as a combination of several arsenide and antimonide forming substances, pre-`- pared either as a powder or in granular form, or as a preparation on a carrier ~` 20 material such as alumina gel, for example. Furthermore, these absorbing sub-. . .
stances, in addition to containing the aforementioned arsenide and antimonide Porming compounds, may be admixed to one or several oxidation agents or ox~gen transfer agents in powder form or granular form, or used as a prepara-tion on a suitable carrier such as alumina gel, ~or example. Lastly, these absorbing substances mR~ be composed of one or several oxidation agents or oxidation transfer agents in powder form or granular form, or be in the form -~
of a preparation on a suitable carrier material, such as alumina gel, for example.
It should be understood, of course, that the foregoing disclosure ~ -describes only pre~erred embodiments of the invention and that it is intended to cover all changes and modifications of these examples of the invention which fall within the scope o~ the appended claims.

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A device for the catalytic recombination of the oxyhydrogen gas produced by a lead-acid storage battery to water and for returning the water to the battery electrolyte, comprising in combination: a generally gastight housing arranged above the battery electrolyte and connected with the space containing the latter for gas flow communication and for liquid return flow thereto; a catalyst body mounted in the cavity of the housing, the catalyst body serving to recombine the oxygen and hydrogen gases to water; a bed of an absorbing substance surrounding the catalyst body, the absorbing substance serving to eliminate from the oxyhydrogen gas mixture the so-called catalyst poisoning gases, e.g. antimony-hydride and arsenic-hydride which are generated together with the oxyhydrogen gases during battery operation; and means for containing the bed of absorbing substance around the catalyst body.

2. A device as defined in Claim 1, wherein: the housing is substan-tially semi-cylindrical in outline, having an inlcined bottom and including:
a downwardly extending hollow stub connection at the lowest point of the housing bottom, two end faces, a horizontal opening in at least one of the end faces, and a porous body closing off the end face opening; the catalyst body is generally rod-shaped and extends horizontally between the two housing end faces so as to adjoin the porous body; the absorbing substance is granular in form; and the containing means for the absorbing substance is a generally tubular gas-permeable container arranged concentrically with the catalyst body axis so as to form a substantially uniform space around the latter for the accommodation of the bed of absorbing substance.

3. A device as defined in Claim 2, wherein: the gas-permeable con-tainer for the absorbing substance is a tube of ceramic material.

4. A device as defined in Claim 2, wherein: the gas-permeable con-tainer for the absorbing substance is a tube of wire mesh.

5. A device as defined in Claim 2, wherein: the housing includes a hollow plug which is mounted in said end face opening, the plug including a horizontally inwardly oriented flange extension, the flange extension position-ing said porous body as well as one end portion of both the catalyst body and the container for the absorbing substance; and the housing further includes on its opposite end face a second flange extension in alignment with the flange extension of said plug for the positioning of the other end portions of the catalyst body and the container for the absorbing substance.

6. A device as defined in claim 5, wherein: the second flange ex-tension of the housing is outwardly oriented; and the housing further includes a putty seal in said second flange extension which closes the flange extension toward the outside and axially retains the catalyst body and the container for the absorbing substance.