DESCRIPTION

The present invention relates to a process for the production of hydrogen and, more precisely, to a process for the production of hydrogen from sodium.

State of the Art

Hydrogen is the most abundant element in the universe, forms up to 75% of the matter if based on the mass, and more than 90% if based on the number of atoms. Having regard to its general abundance, hydrogen is very rare in Earth's atmosphere (1 ppm), and practically non-existent as H2 on the surface and in the substrate of the Earth.

On Earth only 1% of the whole gases is hydrogen. The most common source of this element is the water, which is composed of two atoms of hydrogen and one atom of oxygen (H2O). Other sources are: most of the organic matter (which includes all known forms of life), fossil fuels, and natural gas. The methane (CH4), which is a sub-product of organic decomposition, it is becoming an increasingly important source of hydrogen.

At the elementary status hydrogen exists as diatomic molecule H2 , and it is known as dihydrogen at atmospheric pressure and at ambient temperature (298 ⁰ K) and is a colourless, odourless, highly flammable gas.

The hydrogen forms compounds with most of the elements, often also by direct synthesis. While the stars are mainly composed of hydrogen in the plasma state and which represents the fuel for thermonuclear reactions, the same it is poorly present on Earth in the free and molecular status, and therefore it must be produced for various uses thereof.

In 1671 , Robert Boyle described the reaction that occurred when iron filings and diluted acids were mixed together, and which generated H2. In 1766, Henry Cavendish was the first to recognize the gaseous molecular hydrogen H2 as a discrete substance, by identifying the gas produced in the metal-acid reaction as "inflammable air" and discovering that the combustion of such gas generated water. In 1783, Antoine Lavoisier gave the element the name of hydrogen.

One of the first uses that were made with hydrogen was as filling gases for balloon and, subsequently, for other types of aircraft. At that time the molecular hydrogen was obtained by the reaction of sulphuric acid with the metallic iron.

This element plays a vital role in providing energy to the universe, through nuclear fusion processes. Huge amounts of energy are released in the form of electromagnetic radiation occurs when the combination of two hydrogen nuclei (deuterium or tritium and protium) in a helium.

The solubility characteristics and the adsorption of hydrogen with various metals are very important in metallurgy (some metals may be weakened by hydrogen) and in the development of secure forms of storage for its use as fuel. Hydrogen is highly soluble in many compounds formed by metals and lanthanides of the D block, and can dissolve within crystalline and amorphous metals.

The hydrogen in the molecular form or dihydrogen H2 it is obtained in the laboratory by the reaction of acids with metals such as zinc.

Industrially, hydrogen it is typically obtained through the following processes:

1 ) water electrolysis;

2) gas reforming of natural gas; and

3) gasification of residues from the refining of petroleum.

Currently, the dihydrogen it is used for the production of ammonia, for the desulfurization of petroleum, as an alternative fuel, and most recently, as an energy source for fuel cells.

The H2 reacts directly with other oxidizing elements. Can produce a spontaneous and violent reaction at room temperature in the presence of chlorine or fluorine, with the formation of the corresponding hydrogen halides: hydrogen chloride and hydrogen fluoride.

Moreover, in recent years there is much talk of hydrogen as a possible energy source for automobiles. The H2 used as fuel in the means of transport, by reacting with O2, would produce as the only waste product of the water, completely eliminating CO2 emissions and climatic-environmental problems associated with them.

It is known that use the dihydrogen as a fuel has several advantages. For example, and with the current technological development, hydrogen can be effectively used for energy as a fuel in internal combustion engines used on some prototypes of cars.

Moreover, current developed fuel cells, represent an alternative way to get energy in the form of electricity by oxidation of hydrogen without passing by direct combustion for a greater efficiency in a future in which the production of hydrogen may be from renewable and non-fossil fuels.

According to the proponents of the so-called "hydrogen economy" these two hydrogen technologies, in addition to solving the energy problem they would also be able to offer a clean alternative to internal combustion engines powered by fossil fuels.

The real problem, however, is far upstream: the atomic and molecular hydrogen is very poor in nature, as the element itself it is combined with other elements in various compounds on the earth's crust; therefore it is not a primary source of energy as are natural gas, oil and coal, as it must be produced artificially by spending energy from primary energy sources.

Therefore, to date the use of hydrogen as an energy vector is employable only (i.e. as a means to store and transport the energy available where appropriate), while the cycle of production / use of hydrogen still results inefficient from the thermodynamica!ly side, since its production would require more energy than is generally that then make available through its 'combustion'.

By the laws of thermodynamics, the extraction of hydrogen from water cannot take place then as reverse reaction at zero cost, i.e. without producing work. Any extraction method thus involves a cost that is equal to the energy released subsequently by the combustion of hydrogen in the form of dihydrogen if to this end it uses the exact reverse process.

Currently the dihydrogen obtained from different sources such as solar, biological or electrical sources has a production cost, in terms of energy, much higher than that of its combustion to obtain energy.

Typically, hydrogen H2 can be produced with a net gain of energy from fossil fuels, such as methane (synthesis reactions are in fact different from those of combustion), but as such it is a non-renewable energy that is intended, however, to depleted over time and with direct CO2 emissions.

Finally, the costs for the construction of the infrastructure necessary to make a full conversion to a hydrogen economy would be substantially higher.

Another way hydrogen may be used effectively as a source of energy, regardless of any production process, is that of nuclear fusion or in a plant with a hypothetical thermonuclear fusion reactor fed by deuterium or tritium, a technology which is currently still in development. This technological solution could solve the world's energy problems such as nuclear reaction in small amounts of hydrogen produce huge amounts of energy. However, it is a process technologically complicated to manage on Earth and still the subject of intense research.

So, currently, there are four modes of use of hydrogen for the production of energy: 1) Chemical combination of H2 and O2 from air, through conventional burners and catalytic processes, as occurs in internal combustion engines, while also allowing wide home applications;

2) Combination of electrochemical H2 with O2 without the generation of flames and for producing electricity directly in a reactor known by the name of the fuel cell (or stack) ;

3) Union of hydrogen nuclei in a reactor called Tokamak, during the process known by the name of nuclear fusion; and

4) The chemical combination of the H2 with O2 in an aqueous medium in a conventional boiler to produce steam engine, in cycle known as Chan K'iin.

For example, DE 19517945 (A1 ) describes a reactor as a source of energy, in which the sodium or a compound that includes sodium, is brought into controlled contact in the solid state or liquid water or water vapour, so that it produces a specific defined and controlled amount of hydrogen, which can be used for the energy supply.

Furthermore, WO2010/004 63 A2 describes a device for the generation of hydrogen and its use, in which it is provided the use of a colloidal suspension that comprises between 2 and 60% of particles of alkali metal in suspension in a diluent neutral hydrophobic, and that the suspension is used to produce hydrogen gas. This document also describes a process for producing hydrogen.

Further, there are important problems entailed with the storing and the transporting of H2. The transporting thereof can be made in liquefied compressed gas cylinders, or through dedicated networks. Storing can be done in cylinders under pressure from 200 bar to 700 bar (still to be in the process of approval), in a liquid status instead it is required temperatures of -253 °C in a good-insulated tanks. Another form of storage consists of the reversible chemical reaction with different substances forming metal hydrides, or in liquid form of ammonia Nhb at a temperature of -33.4 ⁰ C.

There is therefore the need for a process for the production of hydrogen which overcomes the above described drawbacks and which allows to provide hydrogen in a energetically convenient and ecologically compatible manner.

Brief description of the invention

The present invention provides a process for the production of hydrogen which provides for the gasification thereof following the stable control of the chemical reaction between elements of easy retrieval, such as sodium and water, in a complete safety, and with low production cost.

The present invention also provides an apparatus for implementing such a procedure.

Thus, the present invention provides a process for the production of hydrogen substantially according to the annexed claims.

Detailed description of the invention

A detailed description of a preferred embodiment of the process for the production of hydrogen according to the present invention will now be given, given by way of non limiting example, with reference to the accompanying figures, in which:

Figure 1 is an elevational view partially illustrating an apparatus for the production of hydrogen according to the process of the present invention;

Figure 2 is a longitudinal section view of the apparatus of the present invention; and

Figure 3 is a top plan view partially illustrating the apparatus of Figure 1. Referring now to the figures there is partially illustrated an apparatus 1 for implementing the method for the hydrogen production according to the present invention.

According to the process of the present invention, a production of molecular gaseous hydrogen that is in the diatomic H2 status it is provided, and obtained in a complete safe according to the following reaction.

With this aim, sodium (Na) can be preferably obtained by electrolysis methods of molten salts in electrolytic cells, and as already known to the state of the art.

It should be pointed out here that with the sake of improving the efficiency of the whole process, the electrolytic cell can be powered by electric power coming from renewable sources such as solar energy (PV).

For example and for illustrative purposes, the production of Na can be obtained according to the method Downs and the present modern methodologies derived from this method, i.e. electrolysis and using the energy from photovoltaic system.

From this controlled reaction is obtained Na and CI2 which may be stored.

The Na thus obtained is conveyed into a reactor 10 in the present apparatus 1 and which it is previously deaerated so as to eliminate as much as possible the presence of O2 inside thereof.

The operation of the apparatus 1 it is divided into two main phases. The first one it is the deaerating, and the second one it is the hydrogen production. First phase

Within the reactor 10 it is contained in an aqueous solution. More precisely, and with particular reference to Figure 1 and 2, the lower part of the reactor 10 is filled with a solution 11 , which is a one (1) molar solution of NaOH (40 Gr per liter) until reaching to about the middle of the lumen of two ports or holes 12 corresponding to outer arms. Then, an inert liquid 13 it is introduced, such as liquid paraffin (or, alternatively, vaseline oil).

In this condition, the filling is completed with the NaOH aqueous solution up to a fluid leakage from valves 14 which are arranged at the upper part of the reactor 10, which obviously have been previously opened. Then the valves are totally closed. So, the emptying of the container is started until a predetermined level which goes not beyond the level inside the arms 120 which are connected to their ports 12.

Subsequently, the Na is conveyed into the reactor, where it comes in contact with the aqueous solution and the following reaction takes place

Na + H ₂ 0 = 1/2 H ₂ + NaOH

which produces H2 in the gaseous status inside the reactor.

As the liquid is removed from reactor 10 via appropriate supply/outflow valve 15 the former volume of liquid it is replaced by an atmosphere of H2. The preliminary operation will end when the level of separation of the two liquids 11 and 13 will drop two centimeters below the lumen of the arms 120 connected with the outside of the reactor (figure 2).

The aqueous solution 11 allows to control the above reaction in a controlled and weighted manner.

The reactor 10 has a storing chamber for the hydrogen (not in the figures) which is connected with a supply line 16, the supply line 16 being arranged at the upper part of the reactor 10, the hydrogen being collected from the upper part of the reactor since produced by the reaction and crossing the aqueous solution 11 and then the inert liquid 13.

Therefore, from the reactor 10 are collected at separate areas of the same both aqueous NaOH and gaseous H2.

The H ₂ is collected.

The NaOH can be used to neutralize the CI2 obtained by electrolysis of the initial method Downs, thus obtaining NaCI, and which may then be reused for the circle of production of Na.

According to the invention, neglecting losses for incomplete reaction, it is provided that raw material is not fed back, but only electricity coming preferably from a supply line (i.e., a photovoltaic system - renewal power).

According to the method and apparatus of the present invention, it is provided that the Na previously obtained by the abovementioned production method it is inserted in special steel metal containers 121 having walls which are permeable to both liquids and gases (Figure 1).

The containers 121 are then mounted in pivoting manner and in an aligned sequence onto a driving chain 122, which allows conveying containers 121 one at a time inside the arms 120 that communicate with the reactor 10.

Moving the transport chain 122 of the containers 121 to the inside of the reactor 10 and through the side arms 120, it is provided that only a predetermined small amount of Na inside the containers be in contact with the aqueous solution 11 to form an atmosphere of H2 until the upper level of separation of the two liquids 11 and 13 at an ideal height of 2 cm below the ports 12 of the arms 120.

In this condition, it is possible to operate by varying the amount of sodium introduced in the containers 121 , and then switch to the second phase of production.

Second phase

For example and according to this embodiment, if a total volume of the reactor be about 10 Lt there is provided a lot of space to increase the production of H2. The two liquids 11 and 13 are not miscible since the paraffin has a lower specific gravity and, therefore, it floats above the aqueous solution of NaOH.

It should here be specified that the function of the paraffin is to allow emptying of the air from containers conveyors 121 , while that of the aqueous solution is to lower the amount of heat produced during the reaction.

The containers 121 with the Na first pass through the inert liquid 13 which causes the deaerating thereof, the air being dispersed outside of the reactor 10. Thus, the deaerated containers enter inside the reactor 10 where the Na-hhO aqueous solution contact the former and then the controlled ^' reaction of H2 production it is obtained.

Following the reaction, H2 collects in the upper part of the reactor 10 where and through the exhaust valves 16 at the cap thereof, the hydrogen it is conveyed to a storage line in the most appropriate manner.

On the other hand, the CI2 that is produced separately from the sodium during electrolysis according to the Downs (or equivalent) method, is recovered in the NaOH solution 11 coming from the reaction inside the reactor. To do this, it is expected that such a aqueous solution containing NaOH it is conveyed through the valves 15 provided at the lower part of the reactor 10 and to a part of the apparatus 1 where reduction occurs by NaOH to NaCI, and returning the sodium to the initial state of NaCI, i.e. the production cycle of Na with electrolysis according to the Downs method.

Finally, according to the present process it may be provided that the electrolytic cell for the production of Na is fed by a current which it is produced from a renewable source such as a photovoltaic system or equivalent.

For example, a photovoltaic plant of 5000A to 7.2 V to 10 kW peak- power, or 55.000A by a 110kW system from peak power. For example, the roof of an industrial building can easily support a 200 kW photovoltaic array starting at a cost of€ 400,000.

The process of the present invention aims to offer a convenient method for producing a significant quantity of a non-polluting fuel is that the H2, since it merely behaves as an energy carrier.

The process speed tested by the applicant in the present case revealed a rate of 10 liters of H2 in a minute, which means that in 100 minutes 1m ³ can be easily obtained according to the present embodiment.

In the late '90s, the production cost of 1 pound (about 0,450 kg) of Na was 0.37 Dollars. Through the present invention, the reaction of 2300,00 gr of Na give 1m ³ of H2 at a total cost of 1.60 Euro/m ³ , and considering that 0,37 Euros is the price, if Na it is produced locally the price thereof drops significantly.

With particular reference now to the issue of the range of the electric cars, it is known that present batteries give a range of about 140 km at a constant speed of 100 km/h before charging thereof, the charging being made via the AC power mains where the energy is mainly produced from a nonrenewable and polluting source.

There are 1 kW internal combustion cells that work by absorbing 14 liters of H2 per minute, and there hydride tanks that can store 10 m ³ of H2 that could provide energy to the batteries for at least 7 hours greatly extending the range of the vehicle itself.

Otherwise, by mixing small amounts of H2 to the combustion air of internal combustion engines by connecting a 1 m ³ hydrides cylinder to the size of a bottle of mineral water from 500cc, consumption is reduced by 30%.

The present invention has a number of advantageous aspects.

A first advantageous aspect is the fact that it provides a definitive solution to the problem of pollution by CO2 and nanoparticles.

A second advantageous aspect is that the present invention provides a solution to the exhaustion of energy resources.

A third advantageous aspect consists in the fact that for the obtaining of the Na elementary through electrolysis in the oven Downs after fusion of NaCI + CaC mixture is exploited the energy from the photovoltaic system. For the production of about 50 kg of Na oven absorbs 4.7 kW of electricity.

A fourth advantageous aspect consists in the fact that the chlorine that is produced separately from the sodium is recovered in NaOH solution wastewater coming from the reactor, thereby returning the sodium to the initial state of NaCI and which falls within the production cycle of Na.

For the transporting of H2 once done, it will be transformed into H2O. So, the cycle ends, carrying the solar energy absorbed by the PV but the losses are minimal, since the transformation of matter was conducted in a substantially reversible manner with minimal losses.

A fifth advantageous aspect consists in the fact that according to the process and apparatus of the present invention there is provided a quick breakeven point related to the cost of the production plants.