BE848047A - CAPTURE AND RECOVERY OF SOLAR ENERGY USING REVERSIBLE PHOTOCHEMICAL ISOMERIZATION, - Google Patents

Description

       

  "Capture and recovery of solar energy using

  
a reversible photochemical isomerization "<EMI ID = 1.1> <EMI ID = 2.1>

  
storage and recovery of solar energy, where one fills an isomerizable composition by a photochemical action in the spectrum

  
 <EMI ID = 3.1>

  
solar radiation from a thin liquid layer containing the low energy isomer, for a time sufficient to isomerize at least a significant part of that isomer into its high energy isomer, and causing then, by heat, the conversion of the high-energy isomer into its

  
 <EMI ID = 4.1>

  
liberated being used to support the heat-initiated conversion, and another part becoming available for thermal energy applications and purposes.

  
The use of sunlight (i.e. solar energy) to supply the energy needs of mankind is of great importance due to the gradual depletion by man of the sources of energy. more common energy, such as fossil fuels, coal, oil and others.

  
One known approach to solar energy capture and use, referred to herein as a "running" solar thermal energy system, is based on the heat produced when a blackened surface is exposed to sunlight. This system uses a solar collector in which a sheet of blackened metal is used to heat a functional fluid, such as air, water or mixtures of water and glycol.

  
The use of flat plate sensors is preferable to the use of the parabolic type, not only because the latter is much more expensive, but also because the flat plate sensor can use diffuse radiation more efficiently. In such a system, the functional fluid, water for example, circulates in the sensor (often on the plate or in tubes or the like, fixed on the rear face of the blackened plate sensor), thus causing the fluid to be absorbed. sensible heat
(increasing the temperature). Many modifications to ur. such a system are possible, but, in the simplest system, the hot fluid is stored in an "energy storage tank", where it remains until the energy is needed for heating or cooling.

   At this time, the fluid can be taken back to pass it through an air conditioning or heating system. During heating or cooling cooperation,

  
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extra energy. Simplicity, security, and the possibility

  
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solar thermal is inexpensive have already led to the commercial installation of prototype systems, for applications such as water heating for homes, offices, schools, libraries and apartment complexes, in some parts of the world.

  
However, a number of problems and disadvantages are inherent in common solar thermal energy systems. Instantaneous maximum efficiency of plate sensors

  
 <EMI ID = 7.1>

  
Average daily intake rate on a sunny day can approach 20 percent. That is to say, with a given solar flux, capable of supplying one million Btu / day to a collector, the water circulated in this collector will gain only 0.2 million Btu / day, mainly due to optical and thermal losses. In addition, a serious limitation of thermal systems is that they can only function efficiently as long as sunlight is appreciable. That is, in a solar thermal energy system, there is

  
a threshold of light necessary before the system can be put into operation. In addition, such a thermal system should include

  
 <EMI ID = 8.1> <EMI ID = 9.1>

  
salts, to spread out the operation of the system overnight and

  
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operation before the system can be switched on. Even on clear winter days in these climates the system could only be used for two or three hours each day. In the cold, cloudy days it is. doubtful that we

  
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rnators.

  
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disadvantages, one of the main being that they are too

  
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naturally and are well illustrated by the photosynthesis carried out by Implantes et al. Non-biological photochemical conversions have also been found to some extent in nature, and have been the subject of a number of investigations in order to obtain a control conversion and provide! energy demanded From solar energy. Photochemical approaches include

  
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Conversion ", page $ 29 &#65533; to 329 of Direct Use of the Sun's Energy, Yale University Press, Newhaven and Londan, 1964. Text cited in

  
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photochemical reactions in the laboratory promise these for the storage and use of solar energy ";" the photopolymeri-

  
 <EMI ID = 28.1>

  
reversible reactions usable with respect to photochemical storage of sunlight "; and" photoisomerization

  
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two-stage device for converting solar energy into electrical energy, the first stage comprising the transformation

  
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chemical from trans to cis of some organic acids.

  
U.S. Patent 1,782,259 reports tests on light-sensitive layers containing, as a sensitive substance

  
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to produce photographic images rather than capturing and recovering solar energy in appreciable quantities, by mentioning only a small number of isomerides for example

  
 <EMI ID = 36.1>

  
 <EMI ID = 37.1> .. trans and cis isomers and their uses.

  
 <EMI ID = 38.1>

  
U.S. Re 28, 225 and 5,753,465 respectively, other cyanine compounds have been proposed for printed films and emulsions.

  
 <EMI ID = 39.1>

  
photo-chromic display and shopping devices using trans and cis indigo'ids are disclosed in U.S. Patent 3,715,212. Many additional patented techniques are disclosed.

  
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as far as is known, none is explicitly stated, proposing that these materials be used directly in themselves by geometric isomerization, for the uptake, recovery, and release for utility purposes of solar energy in the spectrum visible in relatively large quantities.

  
An attractive variation of a solar energy conversion and storage system is that solar energy can be chemically stored by means of a photochemical reaction which is reversible on demand, as shown by the following reactions:

  
Energy capture:

  
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stable energy

  
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heat <EMI ID = 43.1>

  
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energy is greater than that of the starting material, a

  
certain part of the energy, thus stored chemically. can be used immediately in conjunction with any sensible heat absorbed by the manner during its passage through the manifold. The OR

  
.

  
high energy products that accumulate during the day can be stored in storage tank (s) until use. In cases where the capture or reaction phase results in chemical dissociation, the resulting dissociated products can be stored separately and until, by mixing them, reassociation is caused to ensure the release of energy.

  
In other cases where the capture of solar energy results in a single stable high energy chemical,

  
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specific wave, or heat to trigger the release

  
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The basic considerations for a Dobby to be photochemically active are as follows:

  
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solar

  
(2) give an efficient photochemical reaction in the presence of d-2 la

  
sunlight to give one or more products whose energy level will be higher than that of the primitive matter;

  
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as high as possible.

  
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rations where: <EMI ID = 58.1>

  
energy benefit of the geometric isomeric photochemical system of the invention
FIG. 2 represents another more detailed schematic representation of the energy profile of the system of the invention;
- Figure 3 gives a schematic illustration of the sensitization of triplet energies.

  
"In the invention, the ijomerizable photochemical composition used (described in detail below) is exposed after having been dissolved and / or dispersed in water or a liquid aqueous medium (described more fully below). solar and responds photochemically to solar energy from visible light

  
and the near infrared spectrum (i.e. between 350 and 1200 nm) to form the higher energy geometric isomers.

  
This composition containing the isomeric form at a higher energy level is then generally stored until the moment when it is desired to recover the energy it contains. If stored, it should be stored at room temperature or at room temperature.

  
 <EMI ID = 59.1>

  
Alternatively, soon after this formation, the high energy isomer is used to recover this energy, and this recovered energy is stored by some other means such as heat exchange of thermal energy which causes it to pass over a fluid medium. to store it or whatever.

  
In the recovery of stored solar energy, the isomeric form, at high energy level, is "triggered"

  
 <EMI ID = 60.1>

  
original and initial isomer at low energy level, with <EMI ID = 61.1>

  
thermal energy 'by itself, (for example to heat a house, to drive a heat pump, or a motor

  
 <EMI ID = 62.1>

  
into another form of energy for use or storage.

  
After returning the isomerizable composition to its

  
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rations previously described for the capture, storage and recovery of stored energy. The reconversion, or the return of the high energy isomer to the low energy isomer, can be initiated and / or initiated by an initial application of heat and / or

  
 <EMI ID = 66.1>

  
being-exothermic, self-sustains while releasing heat, in excess of what is needed, to maintain isomerization reversal.

  
Certain catalysts, which will be described more fully later, can be used to initiate and facilitate

  
 <EMI ID = 67.1>

  
As a simplified illustration of the mechanism

  
general of the system of the invention, it can be said that a trans isomer of a photochemical composition is converted by solar irradiation

  
in the visible spectrum and in the near infra-

  
red, at least in part, to its cis isomer at a higher energy level

  
high, the latter being subjected, to recover energy, to the

  
heat and / or a catalyst, to be exothermically converted into

  
its original low energy trans isomer. If we are

  
refers to figure 1 which presents a simplified diagram of the profile

  
energy of the photochemical system geometric isomer of the system

  
of the invention, the cis C isomer illustrated exhibits a considerably higher energy level (for example 50 + cal / gm) than the isomer

  
trans T. In figure 1, the vertical coordinate is the level <EMI ID = 68.1>

  
 <EMI ID = 69.1>

  
minimum energy required to come from the sun '

  
 <EMI ID = 70.1> <EMI ID = 71.1> release of energy and is a measure of the stability of the cis isomer with respect to retrogradation to trans, and thus controls the storage potential.

  
AE, the difference in energy between trans and cis isomers and represents the net energy stored in the cis form to be released when needed.

  
The i &#65533; tré system works as follows:

  
Sunlight / absorption of solar energy under the

  
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More catalyst of,

  
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photochemical (or direct) during which the trans isomer is converted to its cis isomer, and a thermal (or retro) reaction II during which the cis isomer is converted back to the trans isomer with release of heat.

  
The representation of the photochemical reaction has been greatly simplified in figure 1. A better representation of the phenomenon encompasses the states of photochemical excitation as shown in figure 2. In general, the trans (T) isomer (reactive), becomes excited. <EMI ID = 78.1>

  
 <EMI ID = 79.1>

  
give the cis (C) isomer (product), is accompanied by the release <EMI ID = 80.1>

  
 <EMI ID = 81.1>

  
system to its original composition, i.e. predominance of the trans (T) isomer along the lower curve; '

  
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(1) the energy of T &#65533; should be low, so as to extend the absorption pectre of the material as far as possible towards and / or in the infrared. We will realize that he will be absorbed even more

  
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system &#65533; in the form of heat.

  
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allow the conversion to be easily triggered.

  
(4) the photochemical reaction and reverse thermal reaction should be efficient and not compete with side reactions. In addition, both isomers must be resistant to

  
deterioration by decomposition or other side reactions under operating conditions.

  
(5) both cis and trans isomers should be very soluble preferably in the order of 60 to 80% solubility (w / v) in

  
the liquid solvent used. The greater the solubility, the greater the amount of energy that can be stored in

  
a given volume.

  
(6) the system, in whole or in part, must not present any serious risk to health or safety. Thus, the cis and trans isomers should not be toxic at the concentrations used.

  
To help you reach and select an <EMI ID = 90.1>

  
special photochemical material for use in the invention, it is possible, after preselection of a storage time and a temperature

  
 <EMI ID = 91.1> reverse reaction, for the release of energy, assuming no catalyst was used to induce the reaction. By way of example, it is thus possible to evaluate the temperature required for

  
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for the reaction, thus detaching the ease of triggering of the.

  
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 <EMI ID = 96.1> <EMI ID = 97.1>

  
rigid uniting structural groups which can adapt, in combination with the bond, to undergo geometric isomeric conversion as shown by the general structures shown

  
 <EMI ID = 98.1>

  

 <EMI ID = 99.1>


  
where L is the rigid bond, which may be a carbon-carbon double bond, or several such bonds, a carbon-nitrogen double bond, or more such bonds, a cyclo ring system

  
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 <EMI ID = 102.1> <EMI ID = 103.1>

  
below:

  

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or an al kyl),

  
 <EMI ID = 106.1>

  
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 <EMI ID = 108.1>

  
can be a carbocyclic or heterocyclic aromatic ring system,

  
and
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  <EMI ID = 110.1>

  
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defined below

  
derivatives of indigo and thio-indigo;

  
modified derivatives of indigo and thio-indigo derived from stilbene;

  
cyanine-type dyes; and

  
codified aromatic olefins;

  
and (b) which possess the properties and meet the structural requirements

  
 <EMI ID = 114.1>

  
The class of compound? indigo and thio-irdigo have structures corresponding to the formulas:

  

 <EMI ID = 115.1>
 

  
 <EMI ID = 116.1>

  
aromatic, either carbocyclic or heterocyclic.

  
 <EMI ID = 117.1>

  
 <EMI ID = 118.1>

  

 <EMI ID = 119.1>


  
 <EMI ID = 120.1>

  
above.

  
In the above class of compounds, it is possible to understand, as products illustrating and representing this class, the:

  
 <EMI ID = 121.1>

  
N, N'-dibenzQylindigo

  
N, N'-dipivaloylindigo

  
 <EMI ID = 122.1> <EMI ID = 123.1>

  
N, N'-bis- (5-chloro-2-nitrobenzoyl) indigo N, N'-bis- {2-chloro-4-bitrobenzoyl) indigo

  
 <EMI ID = 124.1> <EMI ID = 125.1>

  

 <EMI ID = 126.1>


  
or :

  
A and A 'can be C2 or higher lower alkyl,

  
 <EMI ID = 127.1>
(where X and Y can be H, alkyl, aryl, or a combination of the three), or a substituted aroyl where the substituents can be nitro, alkoxy, aroyl oxy, sulfinyl, carboxy, dialkylamino, halo, or a combination of the above, and <EMI ID = 128.1>

  
 <EMI ID = 129.1>

  
can cite the

  
 <EMI ID = 130.1>

  
which have structures corresponding to the formula:

  

 <EMI ID = 131.1>


  
or :

  
 <EMI ID = 132.1>

  
 <EMI ID = 133.1>

  
or H or alkyl),

  
 <EMI ID = 134.1>

  
 <EMI ID = 135.1> <EMI ID = 136.1>

  

 <EMI ID = 137.1>


  
 <EMI ID = 138.1>

  
By way of illustration and representation of the preceding class of compounds :, the following may be mentioned:

  
 <EMI ID = 139.1> <EMI ID = 140.1>

  
 <EMI ID = 141.1>

  
can cite those which have the structures corresponding to the formulas: -

  

 <EMI ID = 142.1>


  
or :

  
n can be 0, 1, 2 or 3;

  
X can be oxygen, sulfur or selenium;

  
 <EMI ID = 143.1> <EMI ID = 144.1>

  
aromatic or non-aromatic, carbocyclic or heterocyclic.

  
 <EMI ID = 145.1>

  

 <EMI ID = 146.1>


  
or :

  
 <EMI ID = 147.1>

  
 <EMI ID = 148.1>

  
are defined above.

  
As part of this class, the following may be mentioned by way of illustration and representation:

  
 <EMI ID = 149.1>

  
3,3'-Diëthyloxathiacyanine iodide 3,3'-Diethylthiacarbocyanine iodide

  
 <EMI ID = 150.1> <EMI ID = 151.1>

  
Modified aromatic olefins have the following structures:

  

 <EMI ID = 152.1>


  
or :

  
 <EMI ID = 153.1>

  
of these groups.

  
 <EMI ID = 154.1>

  
 <EMI ID = 155.1>

  
formula below: <

  

 <EMI ID = 156.1>


  
or :

  
 <EMI ID = 157.1>

  
are defined above.

  
There may be mentioned as products falling within the above class and illustrating the

  
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1,1-Biaciindanylidene

  
Among the stilbene derivatives indicated above by way of illustration in the list, a certain number can be obtained commercially, others have been described in the literature and can thus be prepared by their syntheses described in this literature and the others can be prepared using reactions, methods, techniques, and the like, known for such syntheses.

  
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preparation of compounds of this class.

  
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 <EMI ID = 162.1>

  
 <EMI ID = 163.1>

  

 <EMI ID = 164.1>


  
 <EMI ID = 165.1> <EMI ID = 166.1>

  
naphthylethylene

  
6. 1- (4-Methoxynaphthyl) -2-

  
naphthylethylene
 <EMI ID = 167.1>
  <EMI ID = 168.1>

  
 <EMI ID = 169.1>

  
 <EMI ID = 170.1>

  
acetic at 130 [deg.] C, for 8 hours, It is produced by the reaction a

  
 <EMI ID = 171.1>

  
yellow, o.f. 162 to 163 [deg.] C. Elemental analysis gives C 94.2, H 5.9,

  
 <EMI ID = 172.1>

  
 <EMI ID = 173.1>

  
its structure.

  
The main product of condensation is acid

  
 <EMI ID = 174.1>

  
sation from water as its sodium salt. Free acid
(yield 7%) is recrystallized from acetic acid. The relatively low efficiency may be partly attributed to certain difficulties in the separation phase of operations.

  
The process used for the preparation of compound 2 could allow a higher yield but this process is suitable for allowing

  
 <EMI ID = 175.1>

  
The acid is decarboxylated by heating, in boiling quinoline, with copper chromite as a catalyst, for one hour. The product obtained, which appears to be mainly the desired cis isomer, contaminated with a small amount of trans has a melting point of

  
98-105 [deg.] C; the value given in the literature is 103 to 104 [deg.] C.
(Everett et al, J. Chem. Soc., 601 1948).

  
Compound 3 can also be prepared by the method used for 2, and from the amount of sodium salt of acid

  
 <EMI ID = 176.1> <EMI ID = 177.1>

  
 <EMI ID = 178.1>

  
 <EMI ID = 179.1>

  
Compound 4 can be prepared by condensation

  
 <EMI ID = 180.1>

  
 <EMI ID = 181.1>

  
of a crystalline red product (crystallized from acetic acid),

  
 <EMI ID = 182.1>

  
best synthetic route for these compounds.

  
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chemistry, illustrating and representing the other classes previously defined, and of which we have given the list by names, a small number can

  
be obtained from a research laboratory, other compounds

  
or closely similar compounds are described in the literature

  
and can be prepared according to the indications and by the methods

  
shown there, and the others can be prepared using

  
reactions, processes, techniques, and others, known for their

  
syntheses. For example, derivatives of N, N'-diacyl indigo are

  
typically prepared by the methods of Poaner, Chem. Ber. 59.1815

  
(1926) where the indigo and the appropriate acid chloride are treated under reflux,

  
in common, in pyridine, wring out by pouring it into acid

  
aqueous hydrochloric acid diluted, filtered and dried, then extracted, with

  
ethyl alcohol. Recrystallized, from a solvent

  
suitable, such as acetonitrile, D M F, Benzene / Chloroform mixture, and others.

  
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 <EMI ID = 185.1> <EMI ID = 186.1>

  
 <EMI ID = 187.1>

  
In all cases, these derivatives are recrystallized (and / or chromatography on alumina or silica gel), until purity is obtained by thin-layer chromatography, before using them in the invention.

  
 <EMI ID = 188.1> t '&#65533; ï "'

  
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cement as desired in the invention. Preferably, the photochemical compound employed should, for its solubility to be satisfactory,

  
 <EMI ID = 191.1>

  
the temperature of the solar irradiation that it will have to undergo. By economy

  
 <EMI ID = 192.1>

  
prefer. use a liquid, which is water in a way

  
 <EMI ID = 193.1>

  
Consequently, the invention uses a liquid medium,

  
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The complement of the liquid medium, that is to say up to

  
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mixture of water and alcohol or water and glycol, or their mixtures, in the proportions indicated above, the compounds to be used must then be made more soluble by codifying them chemically -

  
 <EMI ID = 197.1>

  
a substituent improving the water solubility. So a material

  
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 <EMI ID = 199.1>

  

 <EMI ID = 200.1>
 

  
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PO., Hydroxyl or a combination of these groups.

  
By employing these liquids and methods, one can

  
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fire and health, compared to the use of liquids which are pure organic solvents ,. in themselves or which would include predominantly - body fluids

  
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The invention does not only include the selection

  
 <EMI ID = 206.1>

  
possessing the properties suitable and required for the practice of the invention, belonging to the classes defined above of compounds

  
 <EMI ID = 207.1>

  
by known means, different suitable substituents, as well as modifications of photochemical compounds, which have been gilded

  
 <EMI ID = 208.1>

  
tior, comprises the use of a sensitizer, in a proportion greater than 10% by weight of the compound, next to the latter, in the aqueous liquid solubilizing for exposure to solar radiation. By introducing a sensitizer next to the organic compound,

  
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for photochemical storage of solar energy, to longer wavelengths, which can be used by

  
 <EMI ID = 210.1>

  
 <EMI ID = 211.1>

  
photochemical sensitization .. For this technique to be used, the energy storage reaction must not occur

  
 <EMI ID = 212.1>

  
absorption of light, but from a triplet excited state, which is lower. As an example, it is established by the literature

  
 <EMI ID = 213.1> <EMI ID = 214.1>

  
We can find, in the literature, data tables concerning

  
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to form S, and all the competing reactions that may accompany the energy transfer. Thus, one can tacitly make a selection of suitable sensitizers for the reactions.

  
 <EMI ID = 216.1>

  
sensitize to the isomerization of stilbene derivatives.

  
As applied to the storage of solar energy by photochemistry, according to the invention, the use of sensitizers provides the advantage of being able to use a greater proportion of the solar spectrum than is possible without a sensitizer.

  
This is because the sensitizer absorbs light of length

  
 <EMI ID = 217.1>

  
and then transmits the light energy or a good part of it to the photochemically active material in an efficient manner to convert.

  
 <EMI ID = 218.1>

  
 <EMI ID = 219.1> <EMI ID = 220.1>

  
to operate an absorption refrigerator, or for air conditioning or the like. A suitable way to carry out the foregoing operations involves heating a small volume of the cis isomer to the point where the reverse reaction begins to sustain itself (or cascade) as more heat is released. in the reaction than is necessary to initiate it. The remainder of the screw isomer can then be fed into the self-heating (or catalytic) trigger member at a rate such that the reaction continues to maintain itself, while allowing excess heat to be taken up. , by means of a heat exchanger for example, for its subsequent use.

  
 <EMI ID = 221.1>

  
Thermal (or conversion) of the vis isomer to the trans isomer can be brought about by catalyzing this process. Catalytic expansion effectively lowers the activation energy required for the conversion of the cis isomer to the trans isomer and simplifies all that relates to the heat initiation means employed in the invention. Thus, photochemically isomerizable materials which usually require a high temperature (that is to say a large initiation by heat), can in principle undergo thermal expansion at a much lower temperature, in <EMI ID = 222.1>

  
appropriate lyser. Likewise, if the thermal conversion of isomer (1),

  
 <EMI ID = 223.1>

  
 <EMI ID = 224.1>

  
saîre to greatly increase the conversion speed. Hence, '- the fact of employing a conversion because of catalytic heat ensures

  
 <EMI ID = 225.1>

  
when this conversion is carried out, as well as by increasing the rate and / or, by providing means for controlling the rate of conversion of the cis isomer to trans isomer.

  
 <EMI ID = 226.1>

  
in the process of the invention ^ has heretofore been defined in

  
 <EMI ID = 227.1>

  
selected from compounds having these properties and having formulas the structure of which has been defined previously - Using

  
 <EMI ID = 228.1>

  
 <EMI ID = 229.1>

  
activation due to purely thermal expansion, but it,

  
 <EMI ID = 230.1>

  
Materials which have a catalytic effect to initiate or induce the release of the energy of the cis isomer at a temperature required in the absence of catalyst are characterized by the presence of strongly acidic groups, either existing in the form vacancies in the crystal structure of the catalyst or in the form of molecular groups chemically bonded to the catalyst. These acid groups can be either acids

  
 <EMI ID = 231.1>

  
an illustrative and representative list of catalysts meeting these requirements in order to define the class of catalysts which can be used in the invention.

  
 <EMI ID = 232.1>. Metals with acidic-locations on the surface "such as zinc matai; <EMI ID = 233.1>

  
acetic% organic acids can include structures

  
 <EMI ID = 234.1>

  

 <EMI ID = 235.1>


  
 <EMI ID = 236.1>

  
&#65533; &#65533; e 1

  
 <EMI ID = 237.1>

  
is insoluble in the liquid medium containing the photochemically active material.

  
. Any combination of two or more of the above catalysts.

  
The catalytic materials of the class especially and particularly defined above are effective with the compounds

  
 <EMI ID = 238.1>

  
tified as derivatives of indigo and thioindigo and also as modified derivatives of indigo and thioindigo. These catalytic materials have a somewhat lower efficiency with the class defined above and identified as being the stilbene derivatives, and have at least some catalytic effect on the other classes defined above of compounds which have the properties and meet the structural requirements necessary for the practice of the invention. Each of the catalysts of these classes is naturally, and is considered, capable of being used by incorporation into

  
a pressure reduction or conversion device in a geometric form <EMI ID = 239.1>

  
of the process of the invention, a calorimeter based on

  
 <EMI ID = 240.1>

  
The specially constructed calorimeter also included a baseline compensator, and a control heater. This

  
 <EMI ID = 241.1>

  
temperature of the order of 0.001 [deg.] C.

  
In the simulation of the practice of the invention, 200 ml of liquid solution containing the cis isomer were introduced into an inner jacket of the calorimeter, the cis isomer employed being placed in the interior of the calorimeter and having previously obtained by exposure of its isomer

  
 <EMI ID = 242.1>

  
calorimeter is surrounded by an outer jacket, in which approximately 500 ml of a liquid solution containing the isomer has been placed

  
 <EMI ID = 243.1>

  
 <EMI ID = 244.1>

  
ultraviolet ion, and then passing it through a so-

  
 <EMI ID = 245.1>

  
shake the liquid solution containing the tra "s isomer. <EMI ID = 246.1> <EMI ID = 247.1> was removed

  
 <EMI ID = 248.1>

  
 <EMI ID = 249.1>

  
light, 200ml of the irradiated liquid solution which contained the cis isomer was transferred into the inner jacket of the calo-

  
 <EMI ID = 250.1>

  
 <EMI ID = 251.1>

  
 <EMI ID = 252.1>

  
 <EMI ID = 253.1>

  
rimetric.

  
. If desired, after reconversion to its iso- <EMI ID = 254.1>

  
of the calorimeter can be returned to the outer jacket, and the succession of exposure to filtered light, transfer to the inner jacket of the calorimeter and reconverting can be repeated.

  
 <EMI ID = 255.1>

  
endothermic reaction, observed in the heat of a solution of

  
 <EMI ID = 256.1>

  
naphthalene to a solvent of this product contained in the lower jacket of the calorimeter or alternatively by causing an exothermic effect produced by a wire forming a heating resistor.

  
Table 2 below presents typical data obtained by the simulations / illustrating the processes, carried out as just described on several indigo derivatives. In these simulations benzene was used as a liquid medium, but similar results can be obtained, although they are not necessarily identical and equivalent, with soluble derivatives.

  
with water in the aqueous liquid medium of the invention.

  
 <EMI ID = 257.1>

  

 <EMI ID = 258.1>


  
Control experiments:

  
 <EMI ID = 259.1> <EMI ID = 260.1>

  
maximum wavelength of the trans, is taken into account, we have

  
 <EMI ID = 261.1>

  
attending 90% cis isomer so this assumption is reasonable

  
-
(c) Without compensation on a baseline. <EMI ID = 262.1> from the baseline were too wide to compensate.
(e) An abnormally large exotherm was obtained, corresponding to <EMI ID = 263.1>

  
and a half in this operation. The cause of this anomaly which has

  
could be reproduced is unknown.

  
 <EMI ID = 264.1>

  
the energy of this compound in the hope that the short duration of '

  
 <EMI ID = 265.1>

  
relatively large energy. However, the time required to thermally equilibrate the solution after irradiation,

  
 <EMI ID = 266.1>

  
the cis isomer was converted back to trans before measurements could be made.

  
 <EMI ID = 267.1> materialize the efficiency of the relevant catalytic materials, we have

  
 <EMI ID = 268.1>

  
 <EMI ID = 269.1>

  
 <EMI ID = 270.1>

  
 <EMI ID = 271.1>

  
teeth and p-toluene sulfonic acid. '

  
Each of the foregoing catalytic materials has made

  
 <EMI ID = 272.1>

  
 <EMI ID = 273.1> <EMI ID = 274.1>

  
 <EMI ID = 275.1>

  
produced in less than 30 minutes for each of the catalytic materials mentioned,;:

  
apart from molybdenum oxide, for which several hours of exposure are required for complete conversion to the trans isomer. As

  
 <EMI ID = 276.1>

  
stable for more than 24 hours without significant reconversion or return to the trans isomer, in the absence of catalyst.

  
Although the previous simulations were

  
 <EMI ID = 277.1>

  
benzene, similar results can be obtained although they are not necessarily similar and equivalent to the soluble derivatives

  
 <EMI ID = 278.1>

  
 <EMI ID = 279.1>

  
 <EMI ID = 280.1>

  
sufficient to en- convert a significant part into its isomer

  
 <EMI ID = 281.1>

  
 <EMI ID = 282.1>

  
 <EMI ID = 283.1>

  
the trans isomer, the maximum absorption properties of which are

  
 <EMI ID = 284.1>

  
mother cis at a temperature initiating the initiation of an exothermic reconversion into trans isomer, while obtaining the release

  
of thermal energy, and (c) continuation of the exothermic reconversion of the cis isomer into the trans isomer, by use of a part

  
of the thermal energy released and without additional

  
heat, another part of the released thermal energy being transferred out of the exothermic conversion zone, to make it available for usable thermal energy applications.

  
 <EMI ID = 285.1>


    

Claims (1)

the recovery of solar energy, according to claim 1, characterized in that one uses an isomer having properties allowing it to undergo the phases described in <EMI ID = 286.1> <EMI ID = 287.1> this cis isomer being suitable for thermal reconversion into iso- <EMI ID = 288.1> for this thermal reconversion, this compound being chosen from compounds, having the above properties and responding to the following trans isomer formula <EMI ID = 289.1> <EMI ID = 290.1> <EMI ID = 291.1> <EMI ID = 292.1> <EMI ID = 293.1> where (a) L is the rigid bond, which may be a carbon-carbon double bond or more of these bonds, a carbon-nitrogen double bond, or more of these bonds a cyclo- ring <EMI ID = 294.1> <EMI ID = 295.1> <EMI ID = 296.1> which may also be an aromatic or hetero romatic ring system, (b) the cis isomer is heated to a starting temperature the initiation of its exothermic reconversion into trans isomer, with obtaining the release of thermal energy, and (c) the exothermic reconversion of the cis isomer into trans isomer is continued, using part of the thermal energy released and without additional heat input, another part of the released thermal energy being transferred out of the exothermic reconversion zone to make it available for usable thermal energy applications. 3) [deg.] - A method according to claim 2 characterized in that the trans isomer resulting from phase (c) is <EMI ID = 297.1> <EMI ID = 298.1> characterized in that up to 50% by volume of the liquid medium <EMI ID = 299.1> medium after its exposure to solar radiation. <EMI ID = 300.1> <EMI ID = 301.1> <EMI ID = 302.1> <EMI ID = 303.1> by chemically modifying its structure by introducing a number which can range up to 6 of groups providing a solubi- <EMI ID = 304.1> <EMI ID = 305.1> <EMI ID = 306.1> 6 [deg.]) - A method according to claim 2 characterized in that the trans isomer used corresponds to the formula <EMI ID = 307.1> or A and A 'can be hydrogen, alkyl or aryl, <EMI ID = 308.1> certain combination of these groups, <EMI ID = 309.1> or an alkyl), <EMI ID = 310.1> R3 and R'3 can be H, aikyl, aryl, aroyl, alkoxy, aryloxy, <EMI ID = 311.1> <EMI ID = 312.1> <EMI ID = 313.1> <EMI ID = 314.1> <EMI ID = 315.1> substituted aroyl where the substituents can be nitro, alkoxy, aroyloxy, sulfinyl, carboxy, dialkylamino, halo, or a combination of these; <EMI ID = 316.1> <EMI ID = 317.1> alkyl), alkyl, aroyl, or a combination of these groups; and R, and <EMI ID = 318.1> <EMI ID = 319.1> aromatic, carbocyclic or heterocyclic clique. 8 [deg.]) - A method according to claim 2 characterized in that the aqueous liquid medium contains up to 10% by weight of a photochemical sensitizer, the object of which is to shift the maximum absorption of the trans isomer used, towards a wavelength greater than the absorption maximum of this trans isomer in the absence of a sensitizer. <EMI ID = 320.1> <EMI ID = 321.1> or <EMI ID = 322.1> <EMI ID = 323.1> <EMI ID = 324.1> H, alkyl, aryl, or a combination of the three), or a substituted aroyl where the <EMI ID = 325.1> <EMI ID = 326.1> <EMI ID = 327.1> <EMI ID = 328.1> a combination of these groups, and <EMI ID = 329.1> <EMI ID = 330.1> <EMI ID = 331.1> <EMI ID = 332.1> <EMI ID = 333.1> or <EMI ID = 334.1> <EMI ID = 335.1> <EMI ID = 336.1> <EMI ID = 337.1> <EMI ID = 338.1> <EMI ID = 339.1> X is H or alkyl, alkyl, aroyl, or a combination of these groups. As products illustrating 11 [deg.]) - Process according to claim 3 charac- <EMI ID = 340.1> ment, a stilbene derivative corresponding to the following formula: <EMI ID = 341.1> <EMI ID = 342.1> <EMI ID = 343.1> <EMI ID = 344.1> <EMI ID = 345.1> <EMI ID = 346.1> <EMI ID = 347.1> <EMI ID = 348.1> <EMI ID = 349.1> <EMI ID = 350.1> <EMI ID = 351.1> <EMI ID = 352.1> of these groups. <EMI ID = 353.1> <EMI ID = 354.1> a combination of these groups and <EMI ID = 355.1> <EMI ID = 356.1> <EMI ID = 357.1> aromatic, carbocyclic or heterocyclic.