Catalyst bed ignition system for hydrazine propellant

Evans, D. D.

Lee, D. H.

English

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October 15,  1970 
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At ten t ion :  M i s s  Winnie M. Morgan 
FROM : GP/Office of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters 
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I n  accordance wi th  t h e  procedures contained i n  t h e  Code GP 
t o  Code U S 1  memorandum on t h i s  s u b j e c t ,  da ted  June 8, 1970, 
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The fol lowing information i s  provided: 
U.S ,  Pa t en t  No. : 3,298,182 
Corporate Source : C a l i f .  I n s t i t u t e  of Technology 
Supplementary 
Corporate Source : Jet  Propulsion Laboratory 
NASA Pa ten t  C a s e  No.: XNP-00876 
Please note  t h a t  t h i s  p a t e n t  covers  an invent ion  made b y  an 
employee of a NASA con t r ac to r .  Pursuant t o  Sec t ion  305(a) of 
t h e  Nat iona l  Aeronautics and Space A c t ,  t h e  name of t h e  
Adminis t ra tor  of NASA appears  on t h e  f i r s t  page of t h e  p a t e n t ;  
however, t h e  name of t h e  a c t u a l  inventor  (au thor )  appears  a t  
t h e  heading of Column No. 1 of t h e  S p e c i f i c a t i o n ,  fol lowing the  
words ‘I. e e w i t h  respect t o  an  inven t ion  o f ,  . e .‘I 
N 
0 (ACCESSION NUMBER) 
3- Gayle Parker 
Enclosure:  
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https://ntrs.nasa.gov/search.jsp?R=19700031995 2020-03-17T02:10:52+00:00Z
Jan. 17, 1967 J A M E S  E. WEBB 3,298,182 
A D M I N I S T R A T O R  OF THE N A T I O N A L  A E R O N A U T I C S  
A N D  S P A C E  A D M I N I S T R A T I O W  
Filed June 24, 1964 
I G N I T I O N  MEANS FOR MONOPROPELLAN'; 
E 
F I G *  2. I 
1 
lNVENT 1' 
D O N A L D  H. L E  
D A V I D  0 .  E V A  
A T T O f  Z Y  
ed State Patente 
1 2 
the Ranger moon probe program. The purpose of this 
program is to examine the surface of the moon in prepara- 
tion for its exploration by man. The Ranger spacecraft, 
to be launchced by an Atlas-Agena B type launch vehicle, 
will carry a group of cameras for transmitting pictures of 
the lunar surfaces just prior to a “hard” or crash landing 
thereon. The spacecraft carries a low thrust monopropel- 
lant-hydrazine engine used for effecting mid-course trajec- 
tory correction. The mid-course correction engine may 
embody the hydrazine-ignition concept disclosed herein. 
It is well known in the art that hydrazine possesses util- 
ity as a liquid propellant for rocket engines. It may be 
combined with an oxidizer in bipropellant reactions and 
in this form displays excellent self-igniting characteristics. 
Hydrazine may also be used as a monopropellant by de- 
composition in the presence of selected catalysts. The 
heat of decomposition of hydrazine is sufficient to main- 
tain adequate catalyst activity once ignition is obtained, 
but initiating the decomposition presents a special ignition 
problem. 
A number of ways have been tried in the past for beat- 
ing a catalyst bed in a combustion chamber to a tempera- 
ture sufficient to  initiate the decomposition of the hydra- 
zine. Some of the prior art efforts in this area have been 
directed to the use of electrical heaters. Later efforts in- 
FIG. 1 shows a cross-sectional view of a typical decom- 
position chamber and thrust generating unit having a cata- 
lytic bed wherein the upper part of the bed has a solid 
oxidizer coating on each of the catalyst pellets. 
FIG. 2 shows a magnified view of a cross-section of a 
portion of the bed having the coated catalytic pellets lying 
above the uncoated catalytic pellets. 
With reference to FIG. 1, there is shown the cylindri- 
cal decomposition chamber 1 which is provided with a 
!ranular or pellet type of catalyst bed 2 occupying a por- 
tion of the downstream end of the chamber. The catalyst 
bed may o ~ u p y  substantially two-thirds of the chamber. 
The catalyst bed 2 is contained in this area by a pair of 
apertured screen members 3 and 4 on the downstream and 
An example of an application to which the Present in- 15 upstream ends respectively. A frustrum-like headplate 5 
having a flanged perimeter 6 is bolted to an externally 
directed flange 7 on the upstream end of the chamber. 
3,298,182 
IGNITION MEANS FOR MONOPROPELLANT 
James E. Webb, Administrator of the National Aero- 
nauties and Spaee Administration with respect to an 6 
invention of Donald H. Lee and David D. Evans 
Filed June 24,1964, Ser. No. 377,784 
22 Claims. (Cl. 60-251) 
This invention relates to a new method for ignition of 
monopropellant-hydraine in a thrust tYF decomPosltion 
device. The term monopropellant as used herein refers to 
a propellant which is a single material rather than a 
mixture of a fuel and an oxidizer. 
vention is intended is in the small thrust engines used in 
The injection-nozzle 8 through which the hydrazine enters 
is disposed axially of the chamber in the frustrum-shaped 
20 headplate 5 and provides means for injecting the mono- 
propellant into the combustion chamber. The gases pro- 
duced by the reaction within the chamber are then ex- 
hausted through the throat 12. Many satisfactory cata- 
lyst must be heated in order to decompose hydrazine at a 
25 rate sufficient for thrust purposes. The effect of these 
catalyst on the rate of decomposition is enhanced at higher 
temperatures. In this invention the higher temperature is 
achieved by bringing a portion of hydrazine in contact 
with a strong oxidizer coating on a portion of the catalyst 
Upon contact an exothermic reaction is initiated, 
providing sufficient heat to the remaining catalyst bed to 
sustain the catalytic decomposition of additional quantities 
of hydrazine. 
The catalyst is comprised of the carrier pellet 11 having 
35 the catalyst substances impragnated therein. It may be 
used in various shapes or sizes. Examples include a 
pellet of spherical or a cylindrical shape. The preferred 
carrier pellet for the present invention ranges in size from 
a one-eighth to a one-fourth inch sphere. Various types 
40 of carriers may be used in the present invention also. 
Zirconium oxide, silicon carbide, and silicon oxide are 
30 bed. 
jected, from an external source, an oxidizer which was noted as examples. However, aluminum oxide provides 
hypergolic with the hydrazine, thus causing the catalyst the most satisfactory results and is therefore preferred. 
bed to be heated by the resulting combustion. Still further As previously noted, there are known to be numerous 
effqrts attempted to utilize an electric spark or variow compositions which, when heated, catalyze the decom- 
glow Plug devices. The main disadvantage of such Prior 45 position of hydrazine at a rate sufficient for thrust pur- - .  
art ignition systems is that they require auxiliary equip- 
ment which undesirably adds weight and complexity to the 
overall thrust system. Such auxiliary ignition devices 
further detract from the thrfist system by displacing 
needed area and also by their additional cost. 
In the present invention a combustion chamber is pro- 
vided with a catalyst bed wherein a thin layer of catalyst 
pellets are coated with an oxidizer in solid form. A hy- 
drazine flow is introduced into the chamber and under- 
goes a vigorous oxidation-reduction reaction upon contact 
with the coating on the catalyst. The energy released 
from this reaction serves to heat the catalyst bed sufficient 
to decompose the flowing hydrazine upon contact. The 
amount of coating used need only be sufficient to  raise 
the catalyst temperature high enough to initiate decom- 
position of the hydrazine since the heat of decomposition 
then maintains the catalyst at a temperature necessary to 
sustain the decomposition. 
When compared with the prior art, the ignition system 
of this invention is simplified, requires no auxiliary equip  
ment such as separate oxidizer injectors, provides a sub- 
stantially lighter overall system, is less bulky, and has 
superior heating characteristics, all at a lower cost. These 
and other advantages and improvements will become evi- 
dent in light of the following description and drawings 
wherein: 
poses. A few of these are manganese, copper, iron, zinc, 
zirconium, molybdenum, rhodium, osmium, nickel, and 
cobalt. It has been found that individual preparations of 
oo ferric nitrate, nickel nitrate, or cobalt nitrate provide good 
activity in the presence of hydrazine. Likcwisc, com- 
binations of the latter three materials catalyze the hy- 
drazine decomposition. A preferred catalytic compo- 
sition may be prepared from an equimolal solution of 
65 each of the three. In preparing the preferred catalyst 
one moleeach of the nickel nitrate (NiN03), cobalt nitrate 
(CoN03), and ferric nitrate (FeNO,) are dissolved in 500 
grams of water. About one thousand ( I  ,000) grams OF 
carrier pellets, which in the preferred case are the alu- 
5o minum oxide (A.1,03) pellets approximately :i.;,; of an 
inch in diameter, are added to the solution. The pellets 
are soaked in the solution which is then heated to boiling 
for about two hours to drive off the water. The pellets 
are then heated further to 500“ in order to drive off the 
85 nitrate component and reduce the compounds to oxides 
or iron, nickel, and cobalt. This process results in the 
uniform impregnation of the carrier peblets by the catalyst 
and also provides for a catalytic coating, to some extent, 
on the surface of the pellets. 
In FIG. 2 there is shown an enlarged section of the 
7o bed wherein the upper one-fourth inch or more of catalyst 
pellets 11 is coated further with the solid oxidizer 10 so 
5,298,182 
4 
at  temperature sufficient to  decompose still addi- that upon contact with the hydrazine the energy given 
off by the upper pellets is sufficient to heat the lower cata- tional quantities of hydrazine. 
lytic bed to a temperature which will decompose subse- 2. The method of claim 1 wherein said first and second 
quently introduced hydrazine. This further coating may catalyst each comprise an alumina carrier impregnated 
labe the form of a strong oxidizing substance. with a mixture of the oxides of iron, nickel, and cobalt. 
:ire potassium permanganate, potasgium chlorate, sodium 3. The method of claim 1 wherein said first and second 
perchlorate, or potassium nitrate. It has been found, catalysts, each comprise an alumina carrier impregnated 
however, that crystalline iodine pentoxide ( I z 0 5 )  will with a compound selected from the group oonsisting of 
form a highly desirable coating because it possesses ex- the oxides of iron, nickcil, and wbalt. 
wllent thermai and shock stabi.Iity, contains an abundance 10 4. The method of claim 1 wherein the strong oxidant 
of oxygen which enhances its reaction with hydrazine, coating is iodine pentoxide. 
and furthermore is soluble in water. Because of the 5. The method of claim 2 wherein the strong oxidant 
datter characteristic it is readily processed for coating the coating is iodine pentoxide. 
catalytic pellets. 6. A thrust-type rocket engine comprising a combustion 
This second coating is prepared by first dissolving the 15 chamber having first and second ends; 
oxidizing substance in water, which in the preferred case an injection nozzle for hydrazine connected at said 
wild be iodine pentoxide (IZO5). The ratio of iodine fiist end of said chanmber and an exhaust means at 
pentoxideL(Iz05) to water may be varied, depending upon the second end of said chamber; 
the thickness of the coating which is desired. Since the a pair of spaced screens within said chamber and con- 
amcunt of heat produced upon contact between the hy- 20 nected thereto; 
drazine and iodine pentoxide (I2O5) coating will be a a particulate catalyst bed disposed between said screens; 
function of the coating thickness and since maximum a solid coating of a strong oxidizer encapsulating a thin 
heat from the reaction is desirable a thick coating should layer of particles of said catalyst bed, said thin 
be applied to the catalyst. The thickest coating will be layer thing nearest that part of the bed which is 
realized by adding one part of Water to about 1.87 parts 25 Proximate to said injection nozzle SO that injection 
by weitght of the crystalline iodine pentoxide. Likewise of hydrazine through said nozzle onto said coated 
a minimal coating may be obtained by using a lower catalyst causes an oxidation-reduction reaction. 
iodine pentoxide to water ratio. The previously prepared 7. The thrust-type rocket engine as recited in claim 6 
pe]leted catalyst is added to the iodine pentoxide-water wherein said Catalyst Comprises a Carrier impregnated with 
solution in a one to one weight ratio. The solution is 30 a COmWund selected from the group consisting of the 
then placed over a low heat to evaporate the excess Oxides Of and cobalt. 
water until a pasty consistency is obtained. The pellets 8. The thrust-type rocket engine of claim 6 wherein 
are then placed in an Oven at about 300" F. and dried said catalyst Comprises a mixture of the oxides of iron, 
with slow agitation for twelve hours. They must then be cobalt- and nickel. 
stored in an air-tight container. 9. The thrust-type rocket engine of claim 6 wherein 
for a uniform oxidizer coating on the surface of the cats- said catalyst is a mixture comprising the oxides of iron, 
lpst pellets. cob& and nickel and said coating is iodine pentoxide. 
The pellets having the oxidizer coating are then placed 10. The thrust-type rocket engne of claim 6 wherein 
at the end of the bed nearest the fuel inlet and, upon the said oomPrixs alumina impregnated with a com- 
introduction of hydrazine, energy is released which heats 40 pound sekcted ft'om the .WUP Consisting Of the oxides Of 
the catalyst to a temperature sufficient to initiate and sus- iron, nickel, and cobalt and wherein said strong oxidant 
tain the catalytic decomposition of additional hydrazine is iodine pentoxide. 
as it is subsequently fed into the chamber. 11. The thrust-type rocket engine of claim 6 wherein said catalyst comprises alumina impregnated with a mix- 
a study of this disclosure, that the invention itself permits 45 ture of the 'oxides of iron, nickel, and cobalt and wherein 
of arious modifications, alterations, and substitutions, said strong oxidizer coating is iodine pentoxide. 
and that the concept disclosed herein is not limited in use 12. The thmst-type rocket engine of claim 6 wherein 
to hydrazine fuel but is applicable to hydrazine deriva- said cata'b'st comprises a carrier impregnated with a 
tives such as hydrazine nitrate, unsymmetrical dimethyl oompound %Iected the group consisting Of the 
hydrazine, or other fuels such as boron-hydride which 50 oxides of iron, nickel, and cobalt and wherein said Strong 
may be catalytically decomposed. oxidizer coating is iodine pentoxide. 13. An ignition means comprising a particulate catalyst 
Patent is: 1. A method for decomposing hydmzine comprising 56 oxide. tures encapsulated with a solid coating of iodine pent- 
the steps of: 
(1) Contacting a quantity of hydrazine with a first 14. The ignition means of claim 13 wherein said 
catalyst, said first catalyst ,being effective for de- catalyst comprises ailumina impregnated with a mixture 
Of the oxides of iron, nickel, and cobalt. 
3 
Examples 5 
This procedure provides 35 
It will be understood by those skilled in the art, 
What is claimed and desired to be secured by Letters effective for decomposing hydrazine at elevated tempera- 
at temperatures and 
said first catalyst 'being enQaPs'Jlated with a solid 15. The ignition means of claim 13 wherein said catalyst comprises alumina impregnated with a compound selected coating Of a strong Oxidant, whereby at least a POr- from the group consisting of the oxides of iron, nickel, tion of said hydrazine undergoes a vigorous oxida- 
tion-reduction reaction with the oxidant coating and 
whereby the Oxidant coating is consumed with the 
liberation of heat; 
from said oxidation-reduction reaction, said second 
catalyst also being effective for decomposing hydra- 
zine at elevated temperatures, whereby said first and 
second catalysts become heated to the point where 
they are effective for promoting the decompsition 70 
of hydrazine; and 
( 3 )  Contacting an additional quantity of hydrazine 
with said first and second catalysts, whereby the 
hydrazine is decomposed with the liberation of heat, 
thereby maintaining said first and second catdysts 76 ed with a solid coating comprising a strong oxidant. 
and cobalt. 
16. The ignition means of claim 13 wherein said catalyst 
(2) Exposing a second catalyst to the heat llberated 65 from and cobalt. the group consisting of the oxides of iron, nickel, 
17. The ignition means of claim 13 wherein said 
catalyst comprises a carrier impregnated with a mixture 
of the oxides of iron, nickel, and cobalt. 
18. A catalyst bed comprising a first particulate layer 
of catalyst effective for decomposing hydrazine at ele- 
w e d  temperatures and a relatively thin particulate second 
layer of catalyst effective for decomposing hydrazine at 
elevated temperatures, said second layer being encapsulat- 
Comprises a carrier impregnated with a compound selected 
5 
19. m e  catalyst bed of claim 18 whmin  said first 
and second catalyst layers comprise alumina impregnated 
with a mixture of the oxides of iron, nickel, and cobalt, 
and wherein said strong oxidant coating comprises iodine 
20. The catalyst lbed of claim 18 wherein said first 
and second catalyst layers comprise alumina impregnated 
with a compound selected from the mup consisting of 
the oxides of iron, nickel, and cobalt, and wherein said 
21. The catalyst (bed of claim 18 wherein said first 
and second catalyst layers comprise alumina impreg- 
nated with a compound selected from the group consisting 
of the oxides of iron, nickel, and cobalt. 
pentoxide. 5 
strong oxidant coating comprises ipdine pentoxide. 10 
15 
6 ,  
22. The catalyst bed of claism 18 wherein said first and 
second catalyst layers comprise a carrier impregnated 
with a mixcure of the oxides of iron, nickel, and cobalt. 
References Cited by the Jbamines 
UNITED STATES PATENTS 
2,721,788 1011955 Schad --__-_-_-_____ 23-281 
3,021,667 2/1962 Griffin -_____________ 60-35.4 
3,101,589 8/1963 Hamrick et a1. _ _ _ _ _ _  23-281 X 
3,120,738 2/1964 Webb --_-_-___-____ 60-35.6 
MARK NEWMAN, Primary Examiner. 
CARLTON R. CROYLE, Exminer. 
D. HART, Assistant Examiner. 


Ignition means for monopropellant Patent

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