Patent Application: US-92754510-A

Abstract:
an oxygen - generating liquid composition is described comprising compositions of water plus lithium chlorate as a saturated solution and as a mixture of saturated solution plus precipitated solids . the composition further comprises catalysts . the oxygen is produced via thermal decomposition . uses of the composition include generation of oxygen for power production or for breathable air . a principal benefit is that the composition is an easily handled liquid stored in un - pressurized tank .

Description:
the present invention is an oxygen generating liquid composition consisting of lithium chlorate plus water that will decompose into its metal chloride plus free oxygen with the application of heat . for the present invention the oxygen generating liquid composition is considered to include liquid solutions and mixtures of saturated liquid solutions with solids . the invention may also comprise any of a number of additives . preparation of the compositions of the present invention can generally be achieved by simply mixing the ingredients . data to understand the oxygen storage benefits for the subject invention are provided in table 1 and drawing sheet 1 . in one embodiment of the invention a saturated solution can be the storage method of choice . table 1 shows the oxygen storage density , both gravimetric and volumetric , for the compositions of the present invention as a saturated solution . drawing sheet 1 shows a comparison of the subject invention in its saturated solution embodiment to other oxygen generating compositions . credit is given to reference 1 for the initial 17 compositions ( oxygen gas ( 3000 psi ) through solid lithium perchlorate ). the subject invention lithium chlorate data has been included in drawing sheet 1 to show its comparison to prior art compositions . from drawing sheet 1 it can be seen that the subject invention has the best oxygen storage metrics of any liquid composition other than cryogenic liquid oxygen . cryogenic liquid oxygen suffers from the complexities of storing and handling a cryogenic fluid along with substantial hazards and steady evaporation . in another embodiment of the invention , a mix of saturated solution and solids can be the storage method of choice . such a storage method might be chosen to minimize stored weight or to improve the thermodynamics of decomposition since it minimizes the water content of the composition . as an example , such a solids plus liquids composition would be a solution with an 80 c saturation temperature stored at below 80 c with precipitated solids present . since lithium chlorate forms several hydrates as noted in reference 2 the mixture will include saturated solution plus solid hydrates . delivery of the full quantity of lithium chlorate as an easy to handle liquid may be accomplished in two ways . the stored liquids / solids mixture may be heated , using waste heat from the thermal decomposition process or other heating means , to return the solids to solution . alternatively , additional water , e . g . using recycled water from the thermal decomposition process or other external water source , may be added to the storage tank to return the solids to solution . the required increased temperature or added water is modest to yield the desired easily handled liquid . the present invention may be used in energy generating systems wherein the oxygen is combusted in a power cycle , or used in a fuel cell , or used in a bipropellant system where it is mixed and combusted with a fuel in a combustion chamber . for such applications , it is important that the energy required for decomposition not exceed the energy produced from the generated oxygen . two thermal decompositions of the subject invention composition were performed in order to validate its oxygen generating properties and to develop the data necessary to assess the thermodynamics of the thermal decomposition process . the first test used a solution with a specific gravity of 1 . 27 and a weight percent of lithium chlorate of 38 %. the second test used a solution with a specific gravity of 1 . 81 with a weight percent of lithium chlorate of 81 %. the second test included the lithium chloride product from the first test in the solution to evaluate the self catalysis effect per reference 3 . the key parameters identified in these tests were the temperatures at which significant decomposition started and stopped . this was determined by observing the volume rate of oxygen gas production . test # 1 , start of significant decomposition : 385 c ; end of decomposition : 466 c test # 2 , start of significant decomposition : 324 c ; end of decomposition : 448 c using the above temperatures the thermodynamics for the saturated solution embodiment of the composition have been evaluated as shown in table 2 . this analysis was performed for atmospheric pressure conditions with 20 c starting temperature . the energy to boil the water included the effect of boiling point elevation using the clausius - clapeyron equation . the energy calculations assume decane as the fuel ( using lower heating value ), ignore the exothermic heat of decomposition , and assume a simple system with no recuperation of the thermal energy used in oxygen production . from this analysis it can be seen that the energy produced significantly exceeds the energy consumed . the overall efficiency of a system using the subject invention would depend on the source of the heat for the oxygen production . for a combustion power cycle or a high temperature fuel cell such as a solid oxide fuel cell , the implementation could use waste heat for the thermal decomposition with minimal impact to efficiency . in another implementation of the present invention , catalysts may be used to facilitate the decomposition and improve the thermodynamics or to allow for simplified implementation or apparatus . such an implementation might have a fixed bed catalyst such as platinum ( pt ), palladium ( pd ), or manganese dioxide ( mno 2 ) placed in the reaction chamber . it is known from reference 4 that the decomposition reaction is self - catalyzing by the lithium chloride product . therefore the subject invention could be enhanced by dissolving lithium chloride in the solution as a catalyst . the test results discussed above showed a 60 c reduction in the temperature of significant decomposition with lithium chloride in the solution . as discussed in reference 3 other catalysts could include cobalt chloride ( cocl 2 ), or manganese chloride ( mncl 2 ) both of which have good solubility in water and they catalyze similar chlorates . suspended but undissolved catalysts could be manganese dioxide particles . the composition of the present invention and the catalysts can be delivered and mixed by pumping or pressure feed methods known in the art . in another implementation of the present invention , for the generation of breathable oxygen , the method of use can be further modified by including a “ chlorine getter ” such as barium peroxide ( bao 2 ) to eliminate the trace amounts of chlorine resulting from the decomposition of the present invention . these methods are well defined in the art for solid “ oxygen candles ” using similar compounds such as sodium chlorate . in addition to water and lithium chlorate the composition may include additives to modify certain properties of the liquid . these additives usually total less than 1 percent by weight of the composition . for example , the composition may include a colorant , which allows the liquid to be more easily seen to facilitate location of a spill for cleanup . another additive may be a thixotropic agent , which can improve the general handling properties of the liquid , such as pumping and pouring . another additive might be a surfactant , which can be used to provide smaller droplet size in a spray system should the oxygen generating apparatus demand spraying and atomization of the liquid . in addition to the defined advantages apparent in the methods of use , the liquid compositions have good safety properties . they are not combustible alone and are not considered shock sensitive . given the water content they are more stable and less prone to combustion when in contact with flammable materials than the solid form of any chlorate or perchlorate . the subject invention presents skin and eye irritation hazards , but reduced compared to other liquid oxidizers , such as fuming nitric acid . as a liquid composition inhalation risk is considered minor . ingestion is the only significant risk . in addition , water based clean - up of spills offers another advantage . since the compositions are fundamentally water based , spill clean - up is expected to be a straightforward water based process . as evident to those skilled in the art , various modifications can be made in light of the foregoing disclosure without departing from the spirit or scope of the disclosure . it is therefore understood that such modifications are covered within the scope of this disclosure . u . s . pat . no . 4 , 981 , 655 ; 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