WO2011009183A1

WO2011009183A1 - Photochemical process for generating electric energy from solar energy, using formaldehyde (ch2o) as the active component

Info

Publication number: WO2011009183A1
Application number: PCT/BR2010/000244
Authority: WO
Inventors: Wellington Saad Larcipretti; Nicolas Del Collado Larcipretti
Original assignee: Wellington Saad Larcipretti; Nicolas Del Collado Larcipretti
Priority date: 2009-07-23
Filing date: 2010-07-13
Publication date: 2011-01-27
Also published as: BRPI0902650A2

Abstract

A photochemical process powered by solar energy, during which the molecules of a combination of water (H₂O) and carbon dioxide (CO₂) are dissociated while passing through a reaction zone, so as to produce the hydrocarbon formaldehyde or methanal (CH₂O) by absorption and concentration of solar radiation through exothermal dissociation caused by fast reversible transformation reactions of electrons and protons in a closed circuit, thus generating electricity.

Description

"PHOTOCHEMICAL PROCESS FOR ELECTRIC POWER GENERATION FROM SOLAR ENERGY, USING FORMIC ALDEIDE (CH ₂ 0) AS ACTIVE COMPONENT"

The present invention relates to a solar-powered photochemical process of molecular dissociation of a combination of water (H2O) and carbon dioxide (CO2) by passing these elements through a reaction zone, producing the hydrocarbon Aldehyde. Formic or Methanal (CH ₂ 0), by absorption and concentration of Solar radiation in exothermic dissociation, through reversible reactions of rapid transformations of electrons and protons, generating electricity.

It is well known that the enormous gap between our current use of solar energy and its huge untapped potential today sets an imperative impetus for 21st century science and technology. The key is to achieve high efficiency, low cost solar energy capture, conversion and storage processes. This is the purpose of this patent application, which is a way to exploit the enormous source of clean and renewable energy represented by solar energy. The use of solar energy presupposes three basic processes: capture, conversion and storage; Capture and conversion can now be achieved with photovoltaic cells, with efficiency <10% and high production cost. Biomass (biofuels), has efficiency <0.5%, with total potential of 5 to 10 TW on the planet. The only process today with good efficiency and low cost is solar thermal technology ($ 0.10-0.15 per kWh). The present technology, based on photochemical processes, represents a huge possibility of exploitation of solar energy, with high power and efficiency / as will be shown later. Continued growth in global energy consumption is expected due to economic and population growth, even in the face of a substantial decline of at least 30% in energy intensity relative to current values by the middle of the 21st century. This demand can be met, in principle, by fossil energy resources, particularly coal [1] -

Given the cumulative nature of CO2 emissions into the atmosphere, the demand for maintaining these levels in the middle of the 21st century will require the invention, development and launch of systems for the production of carbon free energy. Such energies must be on a scale compatible with or greater than the current global potential for energy production from all known combined sources [2]. Within renewable energy resources, solar energy is by far the largest commercially exploitable resource, providing more energy in one hour to Earth than all energy consumed by man in a full year [1]. Given the intermittent nature of solar energy as a primary source of energy, it must be stored and transmitted on demand to the end user. An especially attractive method is to store converted solar energy in the form of chemical bonds, that is, in a reactive process with annual average efficiency, to reduce the current requirements of large areas compared to current photovoltaic cells [1]. The scientific challenges involved in this process included research to capture and convert solar energy and then store this energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as formic aldehyde (CH ₂ O), or other hydrocarbon species. The safe, clean and sustainable production of energy is undoubtedly the most important scientific and technical challenge facing humanity in the 21st century. Energy, security, national security, environmental security and economic security will probably only be achieved by focusing on the energy problem in the coming decades.

Meeting global energy demand in a sustainable manner will require not only increased energy efficiency and new methods of using current fossil fuels, but also a considerable volume of carbon-free energy. Numerous factors conspire to support the far-reaching conclusions above and the basic scientific need for the development of a new high-efficiency, carbon-free energy system as the subject-matter of the present invention.

The object of the present invention is the process for storing and converting solar energy to be captured in the chemical bonds in the reactive core, in its potential energy states. The breaking of the water molecule is an example of a more general conversion to a closed cycle of electric power generation. This process involves the evolution of oxygen as one component and the formation of a reduced fuel as another. The basic questions that need to be explored further are immediately confronted when we pose a simple chemical reaction.

2HaO ^hv ■ 2H ₂ + o ₂

4H ⁺ 4e ~ 2H ₂

2H ₂ 0 0 ₂ + 4H ⁺ + 4e ^" Total transformation is a transfer process that involves many electrons (multi-electrons), being generated by photocatalyst (FC) and light (hv), also, to ensure the neutrality of charges in the system, proton transfer has that accompany the electron transfer in the reactive nucleus.

Breaking the water molecule additionally represents measurable thermodynamic and kinetic barriers to breaking and redoing the required molecular bonds and facilitating desired chemical reactions. This is especially pertinent to the issue of water molecule breakdown due to the byproduct resulting from the activation of water in the catalyst where, whether molecular or solid, will generate chemical species that have strong metal-oxygen bonds. Generally, activation of small molecules by sunlight, including CO2, 0 ₂ , and H ₂ 0, share the chemical processes of the multi-electron reaction [18, 19].

From the perspective of the present project, the most direct method for breaking the water molecule is the action of the catalyst directly on water, as exemplified anodyne and cathode reactions below [21 to 38].

In the above process, the system has to react exactly in the opposite direction of a traditional fuel cell. With sunlight participating in the thermodynamic process forming reactions in the core of the system, in the desired direction of oxygen evolution as one of the components, and generation of a reduced fuel (CH ₂ O Form Aldehyde, or other hydrocarbon species), as another. It is not the object of the present patent to use other methods for breaking the water molecule, such as those using types of reactions that are common in organometallic catalysis, which promote the conversion of oxygen from metal oxides, such as: Nucleophilic Attack Hydroxide in High Valence Metallic Oxide, Radical Coupling of Two Oxides, Reductive Elimination of Bis Hydroxides or Bis μ-Oxides, and others [61, 62, 631.

We now turn to the detailed description of the inventive process; Everyone knows that if we pass a direct electric current into water containing enough ions to make it a good conductor, it will "break" into its constituent elements: hydrogen and oxygen. Both hydrogen and oxygen gases exist as diatomic molecules so the equation for this chemical reaction is:

2H ₂ 0 - 2H ₂ + 0 ₂

Prefixes show us that we need two water molecules to produce one oxygen molecule and two hydrogen molecules. If we decompose 36 grams of water (2 moles), we produce 2 moles of hydrogen gas (4g) and 1 mol of oxygen gas (32g). In this reaction, covalent bonds between the hydrogen and the oxygen atom are broken and new bonds between the hydrogen atoms in the H ₂ and O 2 oxygen atoms were formed. This reaction then requires input of energy (Solar in our case). This is due to:

• The reaction absorbs energy to break chemical bonds;

• Energy is released in the form of chemical bonds;

• We will see later that the released energy (114 Kcal) is slightly less than the required Solar input energy (118 Kcal). For any particular chemical bond, say the covalent bond between Hydrogen and Oxygen, the amount of energy required to break this bond is exactly the same amount of energy released when the bond is formed. This value is called Binding Energy. We then need 118 Kcal to decompose

2 Mols of H2O in its elements. In fact, it takes more than 118 Kcal to break down the water into its atoms, as some energy is returned as the atoms immediately bond to form hydrogen and oxygen molecules. We know that:

• The connection energy of the H-O connection is 110 Kcal;

• The connection energy of H-H connections is 103 Kcal;

• The binding energy of O = O connections is 116 Kcal;

• Decomposition of 2 water molecules requires the breaking of 4 HO bonds and thus requires the input of 440 Kcal; • Formation of 2 moles of hydrogen yields 206 kcal (2 x 103);

• The formation of 1 Mol of oxygen yields 116 Kcal;

• The difference between:

^■ The energy released (206 + 116 = 322 Kcal) and - The energy consumed (4 x 110 = 440 Kcal)

• Provides us with the energy consumed: -118 Kcal.

This energy is now chemical energy stored in the bonds of hydrogen and oxygen molecules. The energy stored in this type of reaction is called free energy because it is available for use. It is useful to have a symbol for free energy and we use the letter G (named after Josiah Willard Gibbs, who developed the concept of free energy). A free energy difference is indicated by the letter G preceded by the Greek letter: Delta (Δ). By convention, I will indicate free energy storage with a positive sign. Thus, our reaction will be expressed, in terms of free energy, as follows:

2H ₂ 0 - ÷ 2H ₂ + 0 ₂ , AG = +118 kcal.

If, contrary to what we have seen so far, igniting a mixture of hydrogen (fuel) and oxygen (oxidizing) will result in a dramatic explosion with the release of water vapor. The equation for this chemical reaction is the reverse of what we have studied so far and is expressed as:

2H ₂ + 0 ₂ - »2H ₂ 0 And, as the explosion suggests, this time a release of energy occurs. In fact, the free energy difference is again 118 Kcal. This is because only 322 Kcal is required to break the HH and 0 = 0 bonds, and 440 Kcal were released by the 4 Moles of the HO bonds that formed (The ignition spark provided the initial input of energy, the reaction then provided necessary to ensure that all molecules react). Throughout this patent we will see that in our case it is a cold electrochemical combustion under control, providing abundant electrical energy as a result. We express the fact that energy leaves the system by placing a negative sign before AG.

2H ₂ + 0 ₂ -> 2H ₂ 0, AG = -118 kcal

Using a photochemical catalyst, we will get the energy from the sun to break down water molecules and start our controlled electrochemical combustion. As we discussed earlier, we will have the following reaction:

2H ₂ 0 + 118Kcal (Photons) - »02 + 4H + + 4e-

With the diffusion of carbon dioxide in water, the formation of carbonic acid (H ₂ CO ₃ ) already begins due to the natural affinity between the elements and the high solubility of carbon dioxide in water. The breakdown of water molecules that occurred at the beginning of the process by the incidence of sunlight produces, as already shown, positively charged hydrogen free ions, oxygen and free electrons. Carbon dioxide molecules then combine with these elements to produce more carbonic acid and aldehyde formic or Metanal (CH ₂ 0), which will be the alkaline fuel of our cold electrochemical combustion, according to the reaction:

2C0 ₂ + 4H + + 4e- - »H ₂ C = 0 + H ₂ C0 ₃

Hydrogen protons find an organic acid medium to propagate to the reactor cathode via the carbonic acid electrolyte, and free electrons circulate through the anode via an external circuit to the cathode, with gas being released. according to the reaction with the reactive system anode (Nickel Type NIH81): H ₂ C = 0 + H ₂ C0 ₃ -> 2CO _z + 4H + + 4e-

Electrons from the reactor anode from an external electrical circuit combine here at the cathode with hydrogen protons from the reactor anode from the electrolyte and available oxygen in the reactive nucleus. , for water formation, according to the reaction with the cathode of the reactive system (Silver Type OVOX16):

0 _{2 +} 4H + + 4e- -> 2H ₂ 0 (Exothermic reaction)

We then _^ total in redox reagent system core as shown below: Reactants Products: Methanal (Fuel)

Burning a Metanal molecule releases 126 Kcal of energy. This value represents the difference between the energy required to break reagent bonds (Metanal, Carbonic Acid and Oxygen) and the energy released during the formation of the products (Water and Carbonic Gas), as we will see below. Remembering that the main products of a combustion are usually water and carbon dioxide. Conversely, the synthesis of a Mol of

Metanal requires 126 Kcal input for the following reasons:

In water and carbon dioxide, the differences in electro-negativity between their atoms is high, thus they have polar covalent bonds with high binding energy. These are strong bonds, break with difficulty and release incipient amounts of energy when they form.

In Methanal and Carbonic Acid, the differences in electro-negativity between their atoms tend to be low, thus they form covalent bonds with average bonding energies. These are broken relatively easily, as we can see in the following molecular structure:

110

H O - H

98 I 187 78 I 187 116 110 110 187 187 C = 0 + C = 0 + 0 = 0 ^ - »2H-0-H + 20 = C = 0 98 I 78 I 110

H O - H

383 + 563 116 // 440 + 748 \ 1062 / \ 1188 /

• Covalent bonds in a Metanal Mol require 383 Kcal to break.

• Covalent bonds in a Mol of Carbonic Acid require 563 Kcal to break. • And the double bonding of the oxygen molecule requires another 116 kcal.

This gives a total of 1062 Kcal required to break all reagent bonds in electrochemical combustion.

For the products of this combustion, we have the following conclusions:

• The formation of 2 moles of H ₂ 0 4 involves forming OH bonds, each with energy of 110 kcal / mol, giving a total of 440 kcal.

• The formation of 2 Mol of CO2 involves the formation of double polar covalent bonds, each with energy of 187 Kcal / Mol, giving a total of 748 Kcal.

Therefore, the grand total of 1188 Kcal is released as soon as all product bonds are formed. Subtracting this total from the 1062 Kcal required to break the reagent bonds, we arrive at -126Kcal, which is the free energy resulting from the oxidation of 1 Mol of Metanal (CH ₂₀ ) in the electrochemical combustion process. · For each carbon dioxide molecule of Metanal burned, 4 electrons migrate from anode to cathode in the nucleus of the reactive system to find the final receptor: oxygen molecules.

• Reduced carbon, occurring in hydrocarbons such as formic aldehyde (partially reduced), has a redox E potential of approximately -0.42 v. • Oxygen, as the most electro-negative element in the reactive core, naturally has the largest E: + 0.82 v

The difference (ΔΕ) is then 1.24 volts. Allowing 4 Mols of electrons to cross this potential results in a free energy yield of 114 Kcal. Therefore, in the reactive core we will have a theoretical loss of heat energy equivalent to 12 Kcal (126 - 114).

L · G = - (4) (23,062) (1.24) = - 114 kcal

The process of the present invention is thus capable of supplying practically all the energy received in the form of light (118 Kcal) in the form of electric energy (114 Kcal), with a theoretical potential of 1.24 volts per set (Anode / Cathode) of the reactive system, and electric current directly proportional to the area of the electrodes and the area of sunlight capture. A high power commercial system may contain multiple sets (Anode / Cathode), connected in series, to increase the electrical potential supplied to the external circuit (12V for example).

The process according to the present invention is further explained by the accompanying drawings in which Figure 1 schematically shows the operation of the process object of the present invention, where the reactive core of the system is confined in a photochemical combustion chamber (1) containing the reagents (H ₂ O and CO2) under high pressure, which has an optical window (2) for the input of solar energy and, inside, has the sets (3) cathode (Silver Type OVOX16) and (4) Anode (Nickel Type NIH81) that enable the occurrence of discrete chemical reactions Earlier in this report, the electrolyte housing (6) and the external circuit (7) that enable the circulation of electrical current generated by the system as a function of solar energy captured by the reactor through a closed-loop Redox photochemical reaction previously demonstrated in this patent application. The aforementioned elements that have been used as Cathode (Silver Type OVOX16) and Anode (Nickel Type NIH81) in the reactive core of the system may be made of other materials as long as they allow the above reactions to occur, and have yield equal to or better than obtained.

Figure 2 shows the energy absorbing envelope of the mixture used as a photochemical catalyst to accelerate the previously described chemical reactions, and any photochemical catalyst presenting the same or better energy absorbing envelope may be used to improve yield. proposed system.

By way of example only, tables 1 and 2 below represent the results of a proof of concept performed under normal temperature and pressure (CNTP) conditions, which do not meet the needs of the complete reaction. For the reaction to take place in its entirety, it is necessary to react 1 Mol of H ₂ O with 1 Mol of CO ₂ , which is only possible in a pressurized environment. The results below (CNTP) were obtained by reacting 1 Mol of H ₂ O with approximately 2 to 5 ppm (parts per million) of CO ₂ . This is obviously not representative of the electrical power that can be obtained with a pressurized core, yet it clearly indicates water activation as well as fully validating the equations presented earlier in this report. when we look at tables 1 and 2 below. To carry out the pressurized core reactions we are now researching materials that enable the high internal core pressure of the system coupled with proper transparency of sunlight in all frequency ranges indicated in Figure 2, which will be the subject of a new patent.

Table 1

Water Activation

Table 2

.Partial activation

gives

Water

In the experiment, there are some observations to make here:

i. Throughout the experiment we had the presence of ambient air and therefore O2, CO ₂ and other elements;

ii. The experiment was performed at normal atmospheric pressure (1 atm) and, therefore, the amount of CO2 in the water did not exceed 2 to 5 ppm; iii. The "SUNLIGHT" table was obtained at night without any incidence of light and the "MAXIMUM LIGHT" table was obtained at 12 h, with sun directly on the experiment;

iv. The mentioned short circuit currents remained constant throughout the experiment (one week), varying only, and only, with the highest or lowest incidence of sunlight, linearly;

v. The total volume of reagents was the same in all cases, as well as the type and area of the electrodes. There was no noticeable consumption of reagents for the time of the experiment.

saw. It is worth noting that to achieve the expected high efficiency, in the reactor core we need a reaction in proportion:

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Claims

1/3 CLAIMS

1. photochemical process, powered by solar energy, characterized by a combination of molecular dissociation of water (H ₂ 0) and carbon dioxide (C02), these elements by passing through a reaction zone to produce hydrocarbon or Methanal Formic Aldehyde ( CH ₂ O), by absorption and concentration of Solar radiation in exothermic dissociation, through reversible reactions of rapid electron and proton transformations (2H ₂ O + 2CO ₂ -REDOX- H ₂ C = O + H ₂ CO3 + O2) _/ generating electricity.

Process according to Claim 1, characterized in that the reactive core of the system is confined in a photochemical combustion chamber (1) under high pressure, which has an optical window (2) for the energy input. Solar and, inside, has the sets (3) cathode (Silver Type OVOX16) and (4) anode (Nickel Type NIH81) that enable the realization and occurrence of chemical reactions in the reactor anode (H ₂ C = 0 + H ₂ C0 ₃ 2C0 ₂ + 4H + + 4e-) and the reactive core cathode (0 _{2 +} 4H + + 4e- - 2H ₂ 0), the H ₂ C03 electrolyte compartment (6), and the external electrical circuit (7) which enables the circulation of the electric current generated by the system as a function of the solar energy captured by the reactor through a previously explained Redox closed-cycle photochemical reaction (2H ₂ 0 + 2C02 <-REDOX-> H ₂ C = 0 + H2C03 + 02). The aforementioned elements that have been used as Cathode (Silver Type OVOX16) and Anode (Nickel Type NIH81) in the reactive core of the system may be made of other materials as long as the reactions described above are possible, and have yield equal to or better than obtained.

Process according to Claim 1 or 2, characterized in that in both Formic or Metanal Aldehyde (H ₂ C = 0) as well as in Carbonic Acid, the differences in electro-negativity between their atoms tend to be low. thus, they form covalent bonds with medium binding energies, which can be broken relatively easily, and therefore, the molecular structure of the complete redox reaction in the reactive nucleus is characterized by the molecular chemical model: HO - H

I I

C = 0 + C = 0 + 0 = 0 <r - 2 H - 0 - H + 2 O = C = 0

I I

H O - H

Process according to Claim 1, 2 or 3, characterized in that for each carbon dioxide-burned Metanal molecule, 4 electrons migrate from the anode to the cathode in the nucleus of the reactive system to find the final receptor: molecules. of oxygen. Maximum carbon, occurring in hydrocarbons such as formic aldehyde (partially reduced), has a redox E potential of approximately -0.42 volts. Oxygen, as the most electro-negative element in the reactive core, naturally has the largest E: + 0.82 volts. The difference (ΔΕ) is then 1.24 volts for each reactor Anode / Cathode set, and several sets can be connected in series to increase the electrical potential supplied to the external circuit (12V for example).

Process according to Claim 1, 2, 3 or 4, characterized by the use of a photochemical catalyst to accelerate the reversible reaction in the reactive core of the system, such as 3/3 shows the energy absorbing envelope of the mixture in Figure 2, and any photochemical catalyst having the same or better energy absorbing envelope can be used to improve the yield of the system object of the present invention.