BR102014003438B1 - hydrogen production process, energy production process in a hybrid vehicle, energy production system in a hybrid vehicle and hybrid vehicle - Google Patents

Abstract

PROCESS OF PRODUCTION OF HYDROGEN, PROCESS OF PRODUCTION OF ENERGY IN A HYBRID VEHICLE, SYSTEM OF PRODUCTION OF ENERGY IN A HYBRID VEHICLE AND HYBRID VEHICLE. The present invention is inserted in the electric power industry, more precisely referring to an ethanol dehydrogenation system, which converts ethanol into a more energetic fuel for use in combustion engines, while producing hydrogen, free from carbon monoxide, which is directed to a fuel cell for the production of electric energy, and consequent electric and / or hybrid propulsion of automobiles. Preferably, the present invention relates to a process of energy production in a hybrid vehicle, which comprises the steps of: (a) Providing a catalytic reactor (5); (b) Supply the catalytic reactor (5) with a vaporized fuel stream; (c) Direct the vaporized reagents to the catalytic reactor (5); (d) Carry out in the catalytic reactor (5) dehydrogenation reactions of the liquid fuel; (e) Cool the outlet stream in order to separate the gaseous stream (9) from the liquid fuel stream; (f) Direct the liquid current in order to feed an internal combustion engine (8) to generate energy or return to the catalytic reactor (5); (g) Capture an air flow (11); and (h) Direct the flow (...).

Description

Field of the Invention

[001] The present invention is inserted in the electric power industry, more precisely referring to an ethanol dehydrogenation system, which converts ethanol into a more energetic fuel for use in combustion engines, while producing hydrogen, free from carbon monoxide. carbon, which is directed to a fuel cell for the production of electric energy, and consequent electric and / or hybrid propulsion of automobiles.

Fundamentals of the Invention and State of the Art

[002] Fuel cells are electrochemical devices whose generation of electrical energy occurs through an oxidation-reduction reaction, in which a reducing agent (fuel) and an oxidizing agent (oxidizer) are consumed. Generally, hydrogen is used as a fuel and oxygen from atmospheric air is used as an oxidizing agent.

[003] In relation to traditional forms of electricity generation, fuel cells represent a more advantageous alternative in terms of efficiency and reduction of pollutant emissions.

[004] However, the physical properties of hydrogen gas make it difficult to transport, handle and store safely. Thus, there is a great difficulty in designing mobile applications that use hydrogen gas as one of its fuels. As the volumetric energy density of H2 is very low, H2 storage remains a challenge in terms of weight, volume, safety and cost.

[005] In an attempt to enable the mobile use of hydrogen fuel cells, the proton exchange membrane fuel cell technique, or “Proton Exchange Membrane” (PEM), was created, which is a selective permeability membrane , that is, it allows the transport of protons acting as an electrolytic conductor, while allowing the separation of gases such as hydrogen from other elements, thus enabling the mobility of hydrogen fueled cells by reforming certain fuels during their use, for the hydrogen production in loco.

[006] Thus, certain fuels can be used as carriers of hydrogen, such as ethanol, which in addition to being liquid at room temperature has a large hydrogen production capacity.

[007] In this sense, it is worth mentioning the direct ethanol fuel cells (DEFC), which is a subcategory of PEM fuel cells, in which ethanol is fed directly into the cell. However, its development is limited by the difficulty of breaking the ethanol carbon bond at low temperatures (80 to 120 ° C), and also to oxidize carbon monoxide, as can be seen in the article by R. Kavanagh et al ., “Origin of Low CO2 Selectivity on Platinum in the Direct Ethanol Fuel Cell”, published in “Angewandte Chemie International”, edition 51, number 27, pages 1572 to 1575, in 2012.

[008] As a result, DEFC performance is generally very poor compared to conventional PEM cells, which are fed with pure hydrogen. Even operated at 200 ° C, DEFC based on polybenzimidazole membrane (PBI) has a much lower performance than that of PEM cells fed with pure hydrogen, as can be seen in the article by JJ Linares et al., “Different anode catalyst for high temperature polybenzimidazole-based direct ethanol fuel cells ”, published in the International Journal of Hydrogen Energy, volume 38, pages 620 to 630, in 2013.

[009] Outside the fuel cell, the best performance for generating hydrogen from ethanol is achieved by steam reform.

[010] Documents describing the state of the art of devices capable of producing a hydrogen-rich reaction flow for feeding fuel cell systems, using a mixture of water and a hydrocarbon (such as ethanol), as starting reagents in processes reform catalysts are known. Such devices generally comprise a vaporizer, a catalytic reformer in which ethanol is converted to hydrogen, and carbon dioxide. Systems of this type are used in electric vehicles powered by fuel cells powered by hydrogen from the reform reaction, avoiding the need for storage on board the hydrogen, in gaseous or liquefied form.

[011] The complete ethanol steam reforming reaction can be represented by the equation below. CH3CH20H + 3H20 ^ 2CO2 + 6H2

[012] This is an endothermic reaction, that is, it needs heat to be maintained, more precisely ΔH0298 = 175.5 kJ mol-1. This equation shows that the ethanol steam reforming reaction necessarily involves breaking the carbon-carbon bond, resulting in hydrogen and carbon dioxide (CO2). Furthermore, the conversion of ethanol with water into hydrogen and CO2, for kinetic and thermodynamic reasons, hardly occurs without the formation of other compounds based on a carbon (C1), that is, CO (carbon monoxide) and CHX (mainly methane).

[013] In this way, other reactions are also involved in the process of steam reforming the hydrocarbons in question, and can be illustrated by the equations below. CH3CH2OH # CH3CHO + H2 CH3CH2OH # CH4 + CO + H2 CH3CHO # CH4 + CO CO + H20 # C02 + H2 CH4 + H20 ^ CO + 3H2

[014] It is possible to verify by the equations described that the generation of carbon monoxide (CO) is inevitable during the reform of ethanol. Thus, and depending on the quality of the hydrogen gas flow of the reform reaction, such systems need to incorporate a purification unit or CO filtering devices, since this compound negatively affects the correct functioning of the fuel cell, as it deactivates conventional electrodes, usually Pt / C, which can tolerate less than 10 ppm CO, as can be seen in the article by HF Oetjen et al., “Performance Data of a Proton Exchange Membrane Fuel Cell Using H 2 / CO as Fuel Gas ”, published in the Journal of The Electrochemical Society, volume 143, number 12, pages 3838 to 3842, in 1996.

[015] As can be seen in the specific literature of this technology, purification systems are generally costly and involve several combined processes, such as the catalytic reaction of gas-water displacement, high and low temperature reactions, the preferential oxidation of CO or even selective CO methanation. Other alternative processes may include membrane reactors and selective hydrogen filters. In all of these cases, processes are costly for energy production systems, whether due to costs, dimensions or complexity.

[016] Still, some patent documents specific to the technology in question can be cited, such as, for example, documents that specifically refer to devices for reforming ethanol.

[017] The PCT application WO 2001000320 is an example of such technology, as it describes a process for the reform of ethanol and its integration in a fuel cell system intended for the propulsion of a vehicle.

[018] In particular, this document refers to a system that includes: a hydrogen production unit by ethanol reform comprising a CO removal unit, a fuel cell and a combustion unit for methane and non-hydrogen consumed by the cell, through a series of heat exchangers that manage and use the heat generated in the different reactions.

[019] European document EP 1808327 A1 also describes a method for obtaining electrical energy from fuel cells fueled with hydrogen obtained through catalytic reform of ethanol, as well as its application in any type of vehicle.

[020] The said method comprises a first stage in which ethanol is diluted with water and introduced into a compartment for the preheating of the liquid mixture and its subsequent vaporization. The vaporized mixture is then injected into the reformer, which is a metal or ceramic cylinder containing the catalyst.

[021] A second stage of such a method involves the purification of the reforming hydrogen in order to remove CO through the use of reactors that incorporate selective hydrogen permeability membranes. The waste gases are collected in a device to recover the heat necessary for the complete vaporization of the reagent mixture that enters the reformer.

[022] In addition, other documents can be cited, such as US 20070122667 A1, WO 1999061369 and WO 2002045839, which incorporate autothermal reformers in which the energy required for the reform reaction comes from the joint supply of oxygen from the air together with the ethanol-water using a suitable catalyst for partial oxidation of ethanol to CO2 and water, according to the equation below. CH3CH20H + 2H20 + 0.502 # 2002 + 5H2

[023] However, as previously mentioned, all of these systems depend on stages of purification of reforming hydrogen in order to remove CO.

[024] WO 2004035466 describes a method of dehydrogenation or reforming alcohols. More particularly, such an invention describes a process for dehydrogenating a primary alcohol, such as methanol or ethanol, for the production of hydrogen and its use in a fuel cell for the production of electrical energy. The process uses a dehydrogenation catalyst that contains copper and comprises a supported metal structure.

[025] However, acetaldehyde is an undesirable product alongside products such as CO, methane and unconverted ethanol, as previously mentioned. These elements are burned and converted into CO2 and thermal energy to be used as a heat source in the dehydrogenation and reform reactor.

[026] Thus, in this process, the elimination of CO occurs in additional stages by catalytic reaction of displacement gas-water and by methanation, something that is also not desired.

[027] Yet, another drawback derived from the catalytic reform of ethanol carried out in the different devices mentioned is the gradual generation of coke deposits, which cause the catalysts present in the reformer to be deactivated. For this reason, steam reforming of ethanol (RVE) is usually operated at high temperatures (above 550 ° C), in order to avoid the formation of coke, and thus obtain high hydrogen yield. On the other hand, above 550 ° C the RVE favors the formation of CO thermodynamically, due to the reverse reaction of gas-water displacement, as shown in the previous equations.

[028] Therefore, the development of an ethanol processing system, which prevents or considerably reduces the formation of CO and coke, is necessary.

[029] The authors of the invention in document EP 2455334 describe an ethanol processing system that allows the reform process to be carried out in two phases (pre-reform and reform) which considerably favors cracking of ethanol, avoiding the formation of deposits coke and, consequently, the deactivation of catalytic systems. However, again, CO removal occurs in additional stages of the gas-water displacement catalytic reaction.

[030] In none of the documents cited above, a solution was presented that contemplates the development of a system capable of producing a reaction flow rich in hydrogen for feeding fuel cells, without the need for devices or additional CO removal stages and that considerably reduces the formation of coke.

[031] Still, the cost reduction with catalysts is another important issue to be considered, since the catalysts commonly used in the catalytic reform of ethanol for the production of hydrogen are based on metals such as Ni, Co, Pd, Rh and Pt The last three are noble metals, whose high price is justified given the scarcity of their mineral reserves.

[032] The resolution of these issues can play an important role in the progress and viability of the use of hydrogen and ethanol hybrid fuel cells, applied to mobile media, particularly useful in transport vehicles, which is the main objective of this present invention.

[033] The invention in WO 2004080589 describes a copper-based catalyst supported on zirconia that directly transforms ethanol into ethyl acetate and hydrogen at temperatures from 200 ° C according to the equation below. 2 CH3CH2OH # CH3COOC2H5 + 2 H2

[034] Copper-based catalysts are typically used to dehydrogenate ethanol to acetaldehyde. Although the same amount of hydrogen is released to obtain acetaldehyde, ethyl acetate is preferable due to its lower toxicity and volatility. In addition, acetaldehyde is difficult to handle and has a lower specific heat of combustion than ethyl acetate. Even though RVE can generate much more hydrogen per ethanol molecule, ethanol dehydrogenation generates a CO-free flow of hydrogen, thus not requiring an additional purification stage or filtering devices.

[035] Additionally, the specialized technical literature reports in several documents the developments made in catalysts and fuel reform processes, seeking to solve the problems of the state of the art.

[036] As examples of such documents, the North American document US 7682724 B2, which describes a system and a process for reforming an alcohol, methanol or ethanol, for the production of energy by means of an engine (using the result of the reaction) and a hydrogen cell (using the gaseous result of the reaction).

[037] The reaction involved in this North American document must still be considered as a reform, since it effects the breaking of the carbon-carbon bond, thus causing the previously described equations and substances, something undesirable.

[038] Still, it is possible to verify that catalysts of different types have different reactivity. In this way, copper supported on zirconia has intrinsic reaction catalytic property, which copper alone (as an isolated metal) would not have. The reactivity of Cu-ZrO2, Cu-NiO, or even Cu-Al2O3 are completely different, they only have the copper element in common. Thus, these catalysts cannot be considered similar, even if they contain the same element.

[039] For example, Na (OH) - sodium hydroxide is a strong base used in the manufacture of paper, fabrics and detergents. Ingestion can cause serious and permanent damage to the gastrointestinal system. NaCl - sodium chloride or table salt is essential for animal life. Intake of sodium chloride is essential for human vital metabolism. And, both have sodium (Na) in common, but completely different characteristics.

[040] US7682724 B2 also mentions the creation of carbon monoxide in the hydrogen production process, that is, the mixed product obtained from the respective invention can be used as a source of H2 and / or carbon monoxide in other chemical processes. . The creation of carbon monoxide is detrimental to the correct functioning of the fuel cell and, therefore, different from the techniques proposed by the present invention.

[041] This production of carbon monoxide occurs only when the carbon-carbon bond of the ethanol molecule is split (broken), which determines a catalytic reform. In this case, the nickel catalyst present in the document in question has reactivity to break the carbon-carbon bond, which provides the creation of carbon monoxide.

[042] US7682724 B2 also mentions the use of methane (CH4) produced during the reform as a fuel. The presence of methane confirms that the reaction involved in such a patent leads to the breaking of the carbon-carbon bond of ethanol. Methane is formed only after the ethanol carbon-carbon bond breaks, as are CO and CO2.

[043] Also, the burning of CH4 has a specific heat of combustion much lower than the specific heat of combustion of ethyl acetate. They are different fuels, as well as gasoline and ethanol.

[044] Another state of the art document that can be cited is the North American document US 6827047 B2, which also describes a system and a process for reforming a liquid fuel for the production of energy by means of an engine (using the result of the reaction) and a hydrogen cell (using the gaseous result of the reaction).

[045] In this case, the fuel reform product in this document is an aromatic compound, which has a cyclic carbon chain, which is undesirable in the process. In this case, the hydrogen created by the reform is still contaminated with carbon monoxide.

[046] Also, gasoline, natural gas, ethanol, butanol, can be fuels for internal combustion engines. However, they all have intrinsic properties and chemical formulas, specific to each one.

[047] Other documents that can also be cited are European documents EP 0734765 B1 and EP 1862217 A1, in addition to North American document US 6432871 B1. All of these documents describe different catalysts, comprising nickel, copper or a “Raney alloy”, which is a metallic alloy. All of these catalysts still comprise the same state of the art problems already mentioned.

[048] Unlike the steam reforming reaction of prior art ethanol, the dehydrogenation reaction occurs without breaking the carbon-carbon bond. What is formed from ethanol is its respective aldehyde, that is, acetaldehyde and hydrogen. The main characteristic of the ethanol dehydrogenation reaction is, therefore, not to generate the compounds C1 (CO2, CO and CH4).

[049] Thus, the present invention comprises the generation of CO-free hydrogen from reactions of ethanol, coupled to a fuel cell to produce electrical energy. In this system, the fuel cell generates electrical energy from the electrochemical reaction between the hydrogen obtained from the catalytic reaction of ethanol and oxygen in the air.

[050] Electricity can power a motor, direct or alternating current, an inverter, a battery, or any other electrical system, which thus drives a hybrid or electric vehicle. The energy produced in the fuel cell can still be used to supply a battery or for other applications that require the use of electricity.

[051] Still, the present invention provides for a reaction that involves dehydrogenation, but that is not the classic reaction of ethanol with acetaldehyde formation. There is the occurrence of the so-called coupling dehydrogenation, in which ethanol is taken directly to ethyl acetate and hydrogen, that is, according to the equation below: 2C2H5OH ^ 2H2 + CH3COOCH2CH3

[052] Note that the above reaction is completely different from normal ethanol reform reactions. The reaction of the present invention uses anhydrous ethanol as a reagent, therefore without adding water, which is also an important differential in relation to the reform reaction. And, it generates a compound of type C4 (with four carbons): ethyl acetate.

[053] Another difference observed is in the reaction heat involved in the steam reforming reaction of ethanol compared to the reaction of ethanol to ethyl acetate. The ethanol coupling dehydrogenation reaction to ethyl acetate is almost seven times less endothermic than the ethanol steam reforming reaction.

[054] Specifically, in the process described by this invention, the coupling of acetaldehyde with ethanol is foreseen, in order to take a single reagent (ethanol) to another product of interest in the chemical industry: ethyl acetate, in addition to hydrogen . Ethyl acetate is an ester that is preferable due to its lower toxicity and volatility, presenting specific heat of combustion greater than pure ethanol, thus being a better fuel than ethanol. In this way, the liquid effluent from the dehydrogenation reaction can be used as a fuel or as an additive for ethanol or gasoline, and feed an internal combustion engine.

[055] Other types of fuel cells, including phosphoric acid membrane cells, alkaline electrolyte fuel cells, and solid oxide fuel cells, can be adapted to the system described here. Thus, although the focus of the present invention describes the use of an instantaneous hydrogen generation system from ethanol coupled to the fuel cell in hybrid or electric motor vehicles, its description is not limited to the use of PEM type cells.

[056] The present invention is promising, innovative and low cost, since it uses solid catalysts based on supported copper, applied to the reactions of ethanol and does not require stages for the removal of CO, also dispensing with the need for selective filters of hydrogen composed of palladium membranes, a rare element.

[057] Another aspect of the present invention that sets it apart from prior art documents is the fact that it produces and uses the liquid reaction effluent from ethanol as a liquid fuel or additive to ethanol or gasoline.

[058] The liquid mixture obtained from dehydrogenated ethanol has a specific heat of combustion superior to that of hydrogenated ethanol, and can feed an internal combustion engine in a hybrid vehicle or even feed a combustion electric energy generator that supplies the battery of an electric car. .

[059] In this process, the thermal energy for the catalytic unit through which the ethanol reactions take place can also be provided by the heat provided by the combustion gases of the car exhaust, which operates in a hybrid way with an internal combustion engine and with an electric motor.

[060] An additional advantage of the present invention to automobiles with a hybrid propulsion system is the possibility of reducing the size and, consequently, the weight of the batteries that power the electric motor, which is fundamental for the development of this type of vehicle.

[061] Thus, the present invention solves the problems of the state of the art by combining the production of hydrogen from a renewable liquid raw material (ethanol), using a copper-based catalyst, a material more abundant than rare metals commonly used and of low cost, playing an important role for the progress of hybrid fuel cells of hydrogen and ethanol, mainly applied to vehicular means of transport.

Brief Description of the Invention

[062] The present invention relates to a hydrogen production process that comprises the steps of: (a) Providing a catalytic reactor; (b) Feed the catalytic reactor with a vaporized fuel stream; (c) Direct the vaporized reagents to the catalytic reactor (5); (d) Carry out dehydrogenation reactions of the liquid fuel in the catalytic reactor; (e) Cool the outlet stream to separate the gaseous stream from the liquid fuel stream.

[063] Preferably, the catalytic reactor (5) is tubular with fixed bed, of copper supported on zirconia, of monoclinic crystalline phase.

[064] Furthermore, the hydrogen production process according to the present invention preferably uses ethanol as a liquid fuel, and said liquid fuel is vaporized by means of a pump, a valve and a vaporizer. The dehydrogenation reactions are preferably carried out at temperatures between 200 ° C and 380 ° C, forming mixtures of hydrogen, ethyl acetate, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol. The reaction is preferably carried out with residence time factors W / F between 2 and 200 min, where W is the mass of catalyst in kg and F is the flow of ethanol fed in kg / min, the product being obtained from the reaction acetate of ethyl with selectivity between 20 and 90%.

[065] Preferably, the step of cooling the outlet stream in order to separate the gas stream from the liquid fuel stream is carried out in a heat exchanger, and the process may further comprise an additional step of subjecting the gas stream to a bed of active carbon to promote the adsorption of remaining acetaldehyde and separate it from hydrogen gas, after such a step of cooling the outlet stream. In addition, the process may comprise an additional step of heating the active carbon bed periodically in order to recycle the desorbed acetaldehyde to the catalytic reactor.

[066] The present invention also describes a process of energy production in a hybrid vehicle that comprises the steps of: (a) Providing a catalytic reactor; (b) Feed the catalytic reactor with a vaporized fuel stream; (c) Direct the vaporized reagents to the catalytic reactor; (d) Carry out dehydrogenation reactions of the liquid fuel in the catalytic reactor; (e) Cool the outlet stream in order to separate the gaseous stream from the liquid fuel stream; (f) Directing the liquid stream in order to supply an internal combustion engine to generate energy or return to the catalytic reactor; (g) Capture an air flow; and (h) Direct the gas flow to the fuel cell anode and the air flow to the fuel cell cathode to generate electrical energy.

[067] Preferably, the catalytic reactor is tubular with fixed bed, of copper supported on zirconia, of monoclinic crystalline phase.

[068] Also, the hydrogen production process according to the present invention preferably uses ethanol as a liquid fuel, and said liquid fuel is vaporized by means of a pump, a valve and a vaporizer. The dehydrogenation reactions are preferably carried out at temperatures between 200 ° C and 380 ° C, forming mixtures of hydrogen, ethyl acetate, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol. The reaction is preferably carried out with residence time factors W / F between 2 and 200 min, where W is the mass of catalyst in kg and F is the flow of ethanol fed in kg / min, the product being obtained from the reaction acetate of ethyl with selectivity between 20 and 90%.

[069] Preferably, the step of cooling the outlet stream in order to separate the gaseous stream from the liquid fuel stream is carried out in a heat exchanger, and the process may further comprise an additional step of subjecting the gaseous stream to a bed of active carbon to promote the adsorption of remaining acetaldehyde and separate it from hydrogen gas, after such a step of cooling the outlet stream. In addition, the process may comprise an additional step of heating the active carbon bed periodically in order to recycle the desorbed acetaldehyde to the catalytic reactor.

[070] The process may also comprise a stage in which the liquid fuel stream from the reaction is directed to a storage tank, before being directed to the internal combustion engine.

[071] Still, preferably the energy production process comprises a step of humidifying the gas flow in a saturator filled with water at temperatures between 20 and 90 ° C, as well as a step of filtering the air flow (11) and another step of humidifying the air flow (11) in a saturator filled with water at temperatures between 20 and 90 ° C, before the step of directing the gas flow to the fuel cell anode and the air flow to the fuel cell cathode to generate electricity.

[072] Finally, hydrogen production systems are envisaged in a hybrid vehicle and a hybrid vehicle that comprise hydrogen or energy production processes as defined above.

Brief Description Of Drawings

[073] Figure 1 is a schematic representation of a system according to a preferred configuration of the present invention.

[074] Figure 2 is a table indicating the results obtained by the present invention, showing the conversion of ethanol, product selectivity and the effect of the composition of the liquid mixture on the specific heat of combustion.

[075] Figure 3 is a schematic representation of an exploded view of a unit fuel cell according to a preferred embodiment of the present invention.

[076] Figure 4 is a graph that illustrates the fuel cell polarization curves obtained by means of a potentiostat / galvanostat, according to the prior art and the present invention.

Detailed Description of the Invention

[077] The present invention describes an integrated system for the dehydrogenation of ethanol, which uses ethanol processing in the presence of the catalyst, configured in a compact unit comprising an ethanol reactor and a condenser or collector, to separate the gaseous effluent from net reaction current.

[078] The hydrogen-rich gas stream and free of carbon monoxide feeds a fuel cell that, in turn, generates electrical energy capable of feeding an electric motor.

[079] As can be seen in figure 1, the ethanol reaction liquid effluent which contains ethyl acetate and a fraction of unconverted ethanol, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol can be used to power an engine internal combustion operating in a hybrid car propulsion system.

[080] In this sense, the system according to the present invention comprises a fuel tank (1), preferably ethanol, a pump (2), controlled by a valve (3), a vaporizer (4) and a catalytic reactor ( 5).

[081] Additionally, the system comprises a heat exchanger (6), a storage tank (7) and an internal combustion engine (8). In addition, a fuel cell (10) is provided in the present system, preferably powered by a gas flow (9), rich in hydrogen. The fuel cell (10) generates electrical energy to power an electric motor (13), using the gas flow (9) and an air flow (11), resulting in a water flow (12) as a by-product of the reaction .

[082] Preferably, obtaining hydrogen from ethanol dehydrogenation is carried out in a catalytic reactor (5) which is a solid catalyst, which contains copper in interface with monoclinic zirconia as the active phase. The catalyst generally comprises at least about 10% by weight of copper, preferably about 10% to 90% by weight of copper.

[083] The zirconia as a support can be totally or partially covered by the active phase, containing copper. Commonly in catalysis, the activity of the catalyst is improved by increasing its specific surface area. Thus, a specific surface area of at least about 70 m2 / g is generally preferred for the prepared catalyst, as measured by the Brunauer-Emmett-Teller (BET) method. More preferably, the catalyst has a BET specific surface area of about 50 m2 / g to about 400 m2 / g.

[084] The active phase formed by copper in interface with zirconia can be deposited on the surface of the support using several well-known metallic deposition techniques. These techniques include, for example, electrochemical deposition, physical deposition and chemical deposition. The particularly preferred chemical method for depositing copper on the zirconia support is wet impregnation with copper acetate or copper nitrate salts, however the use of nitrate is preferable.

[085] Obviously, although the copper catalyst supported on zirconia is preferred and described, other catalysts can be cited as, for example, Pt, Pd, Ni, Mo, W, Co, Rh, Ru, Ag, Zn, Cu and Cr and bimetallic NiCu, NiCo, CuZn and CuCr types, which are also useful, and can be used in reduced metal form or in oxide form.

[086] The supports useful for the described process include zirconia, silica, alumina, zeolites, clays, titania, magnesia, chromium oxide, cerium oxide and active coals. Such metals can be added to the support by impregnation, grinding, mixing, coprecipitation or a mixture of these techniques.

[087] The proportion of metal charge on the support is suitably between 0.01 to 20% by mass, normally 0.1 to 10% by mass. Yields of ethyl acetate can reach around 50%, in some cases, in other cases, 20 or 30% in relation to the original alcohol load.

[088] The present invention further describes a process for generating hydrogen free from carbon monoxide from ethanol reactions, in the presence of the catalyst described above. The process for generating hydrogen from the reaction of ethanol according to the invention is not particularly restricted, as long as the contact of ethanol with the catalyst is allowed under temperature conditions between 200 ° C to 380 ° C to carry out the reaction in vapor phase . Different types of reactors can be used, however, the fixed bed reactor is preferable.

[089] In addition, the present invention deals with the use of gas flow rich in hydrogen and free of carbon monoxide as obtained by the techniques described above, applied to a fuel cell that in turn generates electric energy.

[090] In this way, the performance of a PEM unit fuel cell powered with ethanol reaction hydrogen compared to a direct DEFC ethanol fuel cell is also demonstrated. Other types of fuel cells, including phosphoric acid membrane cells, alkaline electrolyte fuel cells, and solid oxide fuel cells, can be adapted to the system described here, not limited to PEM type fuel cells.

[091] The ethanol used as a reagent is preferably anhydrous ethanol. However, alternatively, one can use the hydrated form of ethanol, or other similar fuels that are suitable and produce the necessary substances, without the production of carbon monoxide.

[092] The reaction pressure is not particularly restricted, but it is preferable in the range of 1 to 2 atmospheres (gauge pressure).

[093] As previously described, figure 1 shows the schematic process for obtaining hydrogen instantaneously from ethanol reactions, in the presence of the catalyst, coupled to a fuel cell (10) contemplating the parallel conversion of ethanol into electrical energy and fuel additive.

[094] Ethanol stored in the fuel tank (1) is pumped by the pump (2), and its volumetric flow is controlled by the valve (3) to feed the vaporizer (4). In this way, ethanol in the gas phase comes into contact with the catalytic reactor (5), through which hydrogen is obtained by reactions of ethanol, preferably by dehydrogenation and coupling dehydrogenation co-producing acetaldehyde and ethyl acetate, respectively.

[095] The outlet stream containing the reaction effluent is cooled by a heat exchanger (6), and the liquid product is separated from the gaseous products. The condensed liquid contains mainly ethyl acetate, and a fraction of unconverted ethanol, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol. The mixture of liquid solvents is then preferably stored in the storage tank (7), and can be used to power an internal combustion engine (8).

[096] Also, the heat generated by the combustion of the mixture of these liquid solvents, by means of the combustion gases in the exhaust of an automobile, can be used to supply thermal energy to the catalytic reactor (5).

[097] Finally, the gas stream (9) is rich in hydrogen and has no carbon monoxide. In this way, this flow can be used to directly feed the anode of the fuel cell (10), while atmospheric air or a stream of pure oxygen from an air flow (11) feeds the cathode of the fuel cell (10).

[098] The reactions in the fuel cell (10) generate electrical energy, which can be used to power an electric motor (13) or a battery system, for example, and also generate a flow of water (12) as a by-product of the reaction.

[099] Preferably, the fixed bed reactor operates preferably with the residence time factor (W / F) in the range of 2 to 200 kgCAT min kg-1EtOH.

[100] The present process produces hydrogen and other reaction products from ethanol, but the hydrogen produced does not contain a contaminant such as CO, being pure for feeding the hydrogen cell.

[101] Also, an active carbon bed can be used to promote the adsorption of the remaining acetaldehyde and separate it from the hydrogen gas, in order to increase the partial pressure of hydrogen in the fuel cell supply chain (10). However, other systems to promote the recovery of acetaldehyde can also be used.

[102] Thus, more specifically, the present invention describes a process of ethanol dehydrogenation to generate a reaction gas flow effluent rich in hydrogen free of carbon monoxide, which can be directed to the supply of a fuel cell (10 ) for the production of electricity that can be used to power a battery and / or electric motor (13) to power motor vehicles (14) or electronic mobile devices.

[103] The liquid reaction effluent has a specific heat of combustion greater than pure ethanol, and can be used to power an internal combustion engine (8). In addition, the thermal rejection of the combustion engine (8) can be used to control the temperature of the catalytic reactor (5).

[104] Some examples, purely illustrative, of the system and process described here will be cited.

[105] In a first example, as can be seen in Figure 5, a copper-based catalyst supported on zirconia can be prepared from a ZrO2 support, with a specific BET surface area of 150 m2 / g, prepared by hydrothermal synthesis (51 '), from zirconium nitrate salts (51), or sol gel method (52'), from zirconium alkoxide precursor (52). The solid in liquid solution (53) obtained can undergo an aging process (54) in acidic solution.

[106] After washing and neutralizing (55) the solution's pH, the solid goes through a drying process (56), preferably in an oven, and then through a calcination process (57) with an external air flow (56 ' ), preferably at a temperature between 350 and 650 ° C, preferably at 450 ° C, for a period of 2 to 4 hours, preferably 3 hours, to obtain a monoclinic crystalline phase.

[107] The prepared ZrO2 support then goes through an impregnation step (58) with a solution (58 ’), which can be a copper chloride or nitrate hydrated in methanol solution, for example. The impregnated solid then goes through a new drying step (56) in an oven and then is calcined again by an external air flow (56 ') under a temperature of 300 to 500 ° C, preferably 400 ° C, for a period of 2 to 4 hours, preferably 3 hours. Thus, a catalyst can be produced according to the present invention.

[108] This copper catalyst supported on zirconia, preferably with a mass between 0.4 and 4g, is introduced in a glass tubular reactor, and is then subjected to activation, which consists of a heat treatment with a flow of pure hydrogen at 300 ° C heated at a rate of 10 ° C / min.

[109] After activation, liquid ethanol, with a flow rate of 4 to 20 ml / h, is introduced into the vaporizer at 200 ° C and then ethanol in the vapor phase comes into contact with the catalyst bed. The catalytic reaction is carried out isothermally at a temperature of 250 ° C under autogenous pressure, with a residence time (W / F) of 2 to 200 kgCAT min kg-1EtOH. The outgoing composition of the reaction effluent has selectivity for ethyl acetate ranging from 42 to 63%.

[110] The results obtained under these conditions are shown in figure 2 and, show that the variation in the specific heat of combustion of the ethanol reaction liquid effluent depends on its composition. In figure 2, X is the percentage of conversion of ethanol, with the selectivity in percentage divided between acetaldehyde (AcH), ethyl acetate (AcOEt), methyl ethyl ketone (MEC) and / or butanol (BUT), crotonaldehyde (CROT) , Acetone (PROP). The superscript “o” means that the measured property is based on a temperature of 298.15 K (ie Room temperature); the superscript “a” means 100% ethyl acetate; the superscript "b" means 100% ethanol; and ΔHcombo (kJ mol-1) means the specific enthalpy or heat of experimental combustion obtained for the respective solvent compositions. Thus, this table demonstrates the conversion of ethanol, selectivity of the reaction products, and the effect of the composition of the liquid mixture on the specific heat of combustion.

[111] The reactions of ethanol to obtain the products described in figure 2 can be represented schematically in the equations below, where ethanol is converted into acetaldehyde and then into ethyl acetate, crotonaldehyde, butanol and / or MEC and acetone , respectively. Unconverted ethanol, as well as all recovered liquid effluent including ethyl acetate, can be recycled to the reactor.

[112] Finally, the gas stream rich in hydrogen and free of carbon monoxide as previously obtained, due to the catalytic reaction of ethanol, is humidified in a saturator filled with water at temperatures between 20 and 90oC and introduced into the anode of the cell at fuel (10). While pure oxygen or atmospheric air, also subjected to humidification in the same temperature range of 20 and 90oC, is introduced into the cathode of the fuel cell (10).

[113] The PEM type fuel cell (10) used for testing purposes has electrodes (anode and cathode) of commercial Pt / C (E-TEK Inc) with 20% by mass of Pt, with full Pt charge in the catalyst layers of 0.4 mg / cm2. The membrane / electrode assembly is formed with a proton exchange membrane, typically a Nafion® membrane (H +, DuPont).

[114] This set is placed between graphite plates with serpentine channels, for the circulation of gases and collection of electric current. In the operating system, a set of unit cells is used to form the module with the desired power.

[115] Obviously, although such a set is described, the invention is not limited by these elements, and elements with similar functionalities can be used.

[116] Figure 3 schematically represents a unit fuel cell (10). As can be seen in the figure, the fuel cell (10) according to a preferred configuration of the present invention comprises a hydrogen inlet (21), an oxygen inlet (22) and a water outlet (23).

[117] In addition, the fuel cell (10) has a thermocouple plate (25) with heating inlets (24), graphite plates (26) with gas diffusion channels (27), spacers (28), and a proton exchange membrane (29), which comprises two catalyst layers (30), one on each side.

[118] The temperature of the fuel cell (10) is preferably between room temperature and 120 oC. By means of a potentiostat / galvanostat, it is possible to obtain the polarization curve of the fuel cell (10), illustrated by figure 4. It is observed that the performance in terms of power density of the unit fuel cell of the PEM type fed with reaction ethanol hydrogen is about six times higher than that observed in previous techniques, obtained for a direct DEFC ethanol cell.

[119] Thus, the present invention describes an instantaneous hydrogen generation system from ethanol reactions on copper catalyst supported on zirconia. In this system, the hydrogen produced is free of carbon monoxide and can therefore be directly used to feed a fuel cell (10), preferably of the PEM type.

[120] In particular, the electrical energy generated in the fuel cell (10) is used to power a direct current motor or by means of an inverter, an alternating current motor, which drives a hybrid or electric motor vehicle (14).

[121] The electricity produced in the fuel cell (10) can still be used to supply a battery or for other applications that require electricity use. The hydrogen generation process uses a catalyst with high activity and selectivity for the conversion of ethanol into ethyl acetate at moderate temperatures.

[122] The thermal energy for the catalytic unit through which the ethanol reactions take place is provided by the heat provided by the combustion gases from the exhaust of the car that operates in a hybrid way, with an internal combustion engine (8) and with an engine electric (13). The reaction effluent in the liquid phase contains a mixture of ethanol reaction products suitable for use as a fuel or additive for ethanol or gasoline in internal combustion engines. The production of electrical energy and the way to make full use of all reaction effluent represent a practical and new method for generating energy.

[123] Hydrogen generation from ethanol reactions occurs, preferably, over the copper catalyst supported on zirconia. The conditions of preparation of the catalyst result in high selectivity to ethyl acetate from ethanol reactions.

[124] A specific system that involves the generation of hydrogen from the reactions of ethanol in the presence of the catalyst, as well as its use in a fuel cell (10) to generate energy for an electric or hybrid vehicle comprises: a) Providing a fixed bed tubular catalytic reactor (5) loaded with a copper catalyst supported on zirconia, preferably in the monoclinic crystalline phase with a high specific surface area; b) Feed the catalytic reactor (5) with a stream of fresh ethanol, through a pump (2), a valve (3) and a vaporizer (4), and direct the vaporized reagents to the catalytic reactor (5) at temperature between 200 ° C and 380 ° C for vapor phase reaction forming mixtures of hydrogen, ethyl acetate, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol, the reactor being operated with residence time factors W / F between 2 and 200 min, where W = Mass of catalyst (kg) and F = Flow of ethanol fed (kg / min); c) Carry out ethanol reactions in the catalytic reactor (5) which comprise; dehydrogenation, ketonization and aldolic condensation for the formation of reaction products, obtaining the product ethyl acetate with selectivity between 20 and 90%, in which the reactor outlet current is cooled in a heat exchanger (6) separating the gas flow (9) the net stream; d) Submit the gas flow (9) to the active carbon bed to promote the adsorption of the remaining acetaldehyde and separate it from the hydrogen gas; e) Heat the active carbon bed periodically by recycling the desorbed acetaldehyde to the catalytic reactor (5); f) Direct the liquid current, coming from the heat exchanger (6), to a storage tank (7) that can feed an internal combustion engine (8), or return to the catalytic reactor (5); g) Humidify the purified gas flow (9) separated in item “d” in a saturator filled with water at temperatures between 20 and 90 ° C; h) Capture an air flow (11) and filter it in a system common to that of air filtration in conventional internal combustion engine vehicles (8), and humidify it in a saturator filled with water at temperatures between 20 and 90 ° Ç; and i) Direct the gas flow (9) humidified at the anode as well as the air flow (11) humidified at the cathode of the fuel cell (10) to generate electrical energy.

[125] Finally, a hybrid vehicle is envisaged that comprises the processes of hydrogen production and / or energy production, as defined above.

[126] Thus, the present invention solves the problems pointed out in the prior art by providing a CO-free hydrogen generation system from the catalytic reaction of ethanol coupled to a fuel cell for the production of electrical energy. The liquid reaction effluent can be used as a fuel or as an additive for ethanol or gasoline and feed an internal combustion engine (8).

[127] In addition, such a system additionally limits the coke formation of the catalyst by recycling the catalytic reactor (5).

[128] Although the invention has been widely described, it is obvious to those skilled in the art that various changes and modifications can be made without the said changes not being covered by the scope of the invention.

Claims (27)

1. Hydrogen production process CHARACTERIZED by the fact that it comprises the steps of: (a) Providing a catalytic reactor (5) with a fixed bed tubular monoclinic copper phase supported on zirconia; (b) Supply the catalytic reactor (5) with a vaporized fuel stream; (c) Direct the vaporized reagents to the catalytic reactor (5); (d) Carry out in the catalytic reactor (5) dehydrogenation reactions of the liquid fuel; (e) Cool the outlet stream in order to separate the gaseous stream (9) from the liquid fuel stream. 2. Hydrogen production process, according to claim 1, CHARACTERIZED by the fact that the liquid fuel is ethanol. 3. Hydrogen production process according to any one of claims 1 to 2, CHARACTERIZED by the fact that the liquid fuel is vaporized by means of a pump (2), a valve (3) and a vaporizer (4). 4. Hydrogen production process according to any one of claims 1 to 3, CHARACTERIZED by the fact that the catalytic reactor (5) performs the dehydrogenation reactions at temperatures between 200 ° C and 380 ° C. 5. Hydrogen production process according to any one of claims 1 to 4, CHARACTERIZED by the fact that the reaction of step (d) forms mixtures of hydrogen, ethyl acetate, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol . 6. Hydrogen production process, according to claim 5, CHARACTERIZED by the fact that the reaction of step (d) is carried out with residence time factors W / F between 2 and 200 min, where W is the catalyst mass in kg and F is the flow of ethanol fed in kg / min. 7. Hydrogen production process, according to any one of claims 1 to 6, CHARACTERIZED by the fact that the product obtained from the reaction of step (d) is ethyl acetate with selectivity between 20 and 90%. 8. Hydrogen production process, according to any one of claims 1 to 7, CHARACTERIZED by the fact that step (e) is carried out in a heat exchanger (6). 9. Hydrogen production process according to any one of claims 1 to 8, CHARACTERIZED by the fact that it comprises an additional step of submitting the gas flow (9) to an active carbon bed to promote the adsorption of remaining acetaldehyde and separates it from the hydrogen gas after step (e). 10. Hydrogen production process, according to claim 9, CHARACTERIZED by the fact that it comprises an additional step of heating the active carbon bed periodically in order to recycle the desorbed acetaldehyde to the catalytic reactor (5). 11. Energy production process in a hybrid vehicle, CHARACTERIZED by the fact that it comprises the steps of: (a) Providing a fixed bed tubular catalytic reactor (5); (b) Supply the catalytic reactor (5) with a vaporized fuel stream; (c) Direct the vaporized reagents to the catalytic reactor (5); (d) Carry out in the catalytic reactor (5) dehydrogenation reactions of the liquid fuel; (e) Cool the outlet stream in order to separate the gaseous stream (9) from the liquid fuel stream; (f) Direct the liquid current in order to feed an internal combustion engine (8) to generate energy or return to the catalytic reactor (5); (g) Capture an air flow (11); and (h) Direct the gas flow (9) to the fuel cell anode (10) and the air flow (11) to the fuel cell cathode (10) to generate electrical energy. 12. Energy production process, according to claim 11, CHARACTERIZED by the fact that the catalytic reactor (5) is copper supported on zirconia. 13. Energy production process, according to claim 12, CHARACTERIZED by the fact that the catalytic reactor (5) is of monoclinic crystalline phase. 14. Energy production process according to any of claims 11 to 13, CHARACTERIZED by the fact that the liquid fuel is ethanol. 15. Energy production process according to any one of claims 11 to 14, CHARACTERIZED in that the liquid fuel is vaporized by means of a pump (2), a valve (3) and a vaporizer (4). 16. Energy production process according to any of claims 11 to 15, CHARACTERIZED by the fact that the catalytic reactor (5) performs the dehydrogenation reactions at temperatures between 200 ° C and 380 ° C. 17. Energy production process according to any one of claims 11 to 16, CHARACTERIZED by the fact that the reaction of step (d) forms mixtures of hydrogen, ethyl acetate, acetaldehyde, acetone, crotonaldehyde and methyl ethyl ketone or butanol . 18. Energy production process, according to claim 17, CHARACTERIZED by the fact that the reaction is carried out with residence time factors W / F between 2 and 200 min, where W is the mass of catalyst in kg and F is the flow of ethanol fed in kg / min. 19. Energy production process, according to any of claims 11 to 18, CHARACTERIZED by the fact that the product obtained from the reaction of step (d) is ethyl acetate with selectivity between 20 and 90%. 20. Energy production process according to any one of claims 11 to 19, CHARACTERIZED by the fact that step (e) is carried out in a heat exchanger (6). 21. Energy production process according to any one of claims 11 to 20, CHARACTERIZED by the fact that it comprises an additional step of submitting the gas flow (9) to an active carbon bed to promote the adsorption of remaining acetaldehyde and separates it from the hydrogen gas after step (e). 22. Energy production process, according to claim 21, CHARACTERIZED by the fact that it comprises an additional step of heating the active carbon bed periodically in order to recycle the desorbed acetaldehyde to the catalytic reactor (5). 23. Energy production process according to any one of claims 11 to 22, CHARACTERIZED by the fact that the liquid stream is directed to a storage tank (7) before step (f). 24. Energy production process according to any of claims 11 to 23, CHARACTERIZED by the fact that it comprises a step of humidifying the gas flow (9) in a water-filled saturator at temperatures between 20 and 90 ° C before step (h). 25. Energy production process according to any one of claims 11 to 24, CHARACTERIZED in that it comprises a step of filtering the air flow (11) before step (h). 26. Energy production process according to any one of claims 11 to 25, CHARACTERIZED by the fact that it comprises a step of humidifying the air flow (11) in a saturated filled with water at temperatures between 20 and 90 ° C before step (h). 27. Energy production system in a hybrid vehicle, CHARACTERIZED by the fact that it comprises a hydrogen production process as defined in claims 1 to 10 and / or an energy production process as defined in claims 11 to 26.

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