RU2342317C2 - Method of obtaining hydrogen and device for its realisation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to group of inventions. Hydrogen is obtained by dehydration of organic substrate on the basis of naphtene hydrocarbons in contact with catalyst, containing platinum on carbon carrier (Pt/C). In carrying out dehydration process, catalyst is heated in electrodynamically coordinated resonance mode of electromagnetic field of SHF resonator, excited by fluctuations of "ТМ"_01p type, where p is integer, catalyst Pt/C being placed into reactor made in form of quartz tube, which is placed co-axially with SHF resonator in area of maximal electric field. Device contains system of hydrated organic substrate supply, continuous reactor with Pt/C catalyst in form of granules or powder, SHF resonator, co-axial cable with loop coupler for resonator excitation, fibre-optic sensor, controlling catalyst temperature, amplifier of SHF resonator power, master oscillator, electrically switched over in frequency of electromagnetic SHF fluctuations in band of SHF resonator power amplifier, sensor of control through directional coupler and detector section of SHF resonator power, reflected from inlet into resonator, for automatic resonance SHF resonator tuning, attenuator, electrically controlled for regulating outlet SHF resonator power and supporting optimal catalyst temperature, programme device for controlling process in required modes of obtaining hydrogen.

EFFECT: reduction of energy consumption, increase hydrogen output.

7 cl

Description

The invention relates to methods and devices for producing hydrogen by the dehydrogenation reaction of pre-hydrogenated organic compounds (naphthenic hydrocarbons obtained from aromatic hydrocarbons) under the action of heterogeneous catalysts based on platinum and a carbon carrier and can be used to produce environmentally friendly fuel for automobile fuel cells, and in other devices and means, power plants equipped with hydrogen engines.

At present, when solving the problem of the functioning of the systems of its reversible storage (accumulation) and use, hydrogen can be used as an alternative type of fuel.

The lack of efficient hydrogen storage systems is a limiting factor of its use as automobile fuel.

Currently, a number of materials have been patented that are capable of accumulating a certain amount of hydrogen per unit volume or weight (patents US 5199972, CL B22F 1/02, 1993; US 5702491, CL B01J 7/02, 1997; US 6074447, CL B01J 3/00, 2000; US 618271, CL BKK 15/03, 2001).

However, for all known materials capable of storing hydrogen, there are problems of rapid hydrogen evolution and cyclic use (multiple hydrogenation-dehydrogenation cycles) in relation to fuel cells used in automobiles.

The main disadvantages of such materials are the following.

1. The long time required in general for hydrogen evolution using traditional thermal heating of the catalyst and catalyst system.

2. Significant inertia when changing the modes of thermal heating of the composite catalytic system, affecting the rate of hydrogen evolution and unacceptable for the operation of the fuel cell of the car (start and stop modes, acceleration and deceleration).

3. The high temperature of the process of hydrogen evolution (more than 300 ° C) and the related problems of entrainment of an organic substrate having a boiling point close to the process temperature.

4. The lack of the possibility of multiple refueling of materials with hydrogen, and consequently, of multiple hydrogen evolution at high speed from a composite catalyst system (cyclic mode of filling and separation).

5. The inability to automate the process of hydrogen evolution due to the duration and inertia of the thermal heating system.

A known catalytic method for the production of hydrogen and carbon materials, in which C ₁ -C ₄ hydrocarbon gases are decomposed on a metal-containing catalyst at a temperature of 500-600 ° C, followed by separation of gaseous decomposition products from the carbon material formed on the catalyst. The gaseous decomposition products are separated by hydrogen bonding in contact with aromatic hydrocarbons in the catalytic hydrogenation zone, after which the bound hydrogen in the form of cyclohexane hydrocarbons is separated from the unreacted starting hydrocarbons, which are then recycled to the decomposition zone. Cyclohexane hydrocarbons are sent to the catalytic dehydrogenation zone, where pure hydrogen is formed, and the hydrocarbon dehydrogenation products are returned to the hydrogenation zone. The invention allows to ensure the full degree of conversion of the original hydrocarbon feedstock, as well as to obtain carbon material and hydrogen gas of high purity (RU 2160698, class C01 B 3/26, 2000).

The disadvantage of this method is the high temperature - the process in the dehydrogenation zone is carried out at a temperature of 300-500 ° C on a catalyst containing group VIII metal (s), a multi-stage process, the need for continuous addition of fresh catalyst to the decomposition zone.

Closest to the present invention (the prototype of the invention) is a method of hydrogen evolution based on reversible hydrogenation-dehydrogenation reactions of organic compounds (substrates of various aromatic hydrocarbons) under the action of heterogeneous catalysts based on platinum group metals supported on a carbon or oxide carrier ((RU 2281154, cells B01J 7/00, 2006).

The disadvantages of this method is the following:

- high temperature (270-340 ° C), at which the stage of hydrogen evolution from the composite catalyst system is carried out;

- insufficient for effective use in the fuel cell of the car hydrogen evolution rate achieved by conventional thermal heating of the composite catalyst system, which is confirmed by the experimental data of tables No. 1 and No. 2 of the description of the aforementioned patent);

- the high inertia of the thermal heating system when changing the operating modes of the car (start, acceleration, deceleration, stop) makes the idea of implementing such a method of hydrogen evolution for use in a fuel cell of a car generally problematic;

- insufficient activity of the heterogeneous catalyst used.

The technical problem solved in the present invention is the creation of an effective method for producing hydrogen with a high rate of its evolution by increasing the activity of the used catalyst, reducing energy consumption for hydrogen evolution, increasing the hydrogen yield and eliminating the problem of entrainment of the organic substrate.

To solve this problem, we propose a method for producing hydrogen by dehydrogenating a hydrogenated organic substrate based on naphthenic hydrocarbons in contact with a catalyst containing platinum on a carbon support (Pt / C), in which, during the dehydrogenation process, the catalyst is heated in an electrodynamically matched resonant mode of the microwave electromagnetic field a resonator excited by vibrations of the form TM _01ρ , where ρ is an integer, while the Pt / C catalyst is placed in a reactor made in the form of quartz oh tube, which is placed coaxially with the microwave resonator in the region of the maximum electric field.

The use for activation of the catalyst and the entire composite catalytic system, including the catalyst deposited on a carbon carrier, and an organic substrate, microwave heating in an electromagnetic field of optimal frequency and power allows us to provide the following.

1. Instant, volumetric microwave heating of the catalyst and the entire composite catalytic system, in connection with which a quick, inertia-free hydrogen evolution is achieved by contacting a prehydrogenated organic substrate, for example perhydroterphenyl with a heterogeneous catalyst, for example 15% Pt / C at atmospheric or elevated pressure and temperatures significantly lower (170-270 ° C) than with thermal heating (270-340 ° C).

2. To reduce the operating temperature of the process in order to prevent the entrainment of the substrate (hydrogenated aromatic hydrocarbon) and to ensure the cyclicality of the processes of filling and hydrogen evolution.

3. Eliminate the inertia during microwave heating and provide the ability to automate and control the process of producing hydrogen, and consequently, the operating mode of the car (start, acceleration, deceleration, stop).

As you know, heating of various materials, including a Pt / C type catalyst in microwave resonators, is accompanied by an increase in temperature by the departure of the resonant frequency of the resonator, and therefore constant tuning of the resonator is necessary.

The closest device for implementing the proposed method for producing hydrogen is a resonator with a lower mode of oscillation TM ₀₁₀ , in which tuning to the resonant frequency is carried out by mechanically changing the diameter of the cavity or using mechanical tuning devices (French patent, No. 7338987, 1971).

However, this device does not allow to obtain the inertial tuning of the resonator necessary for implementing the method for producing hydrogen according to this invention.

To implement the hydrogen production method of the present invention, there is provided a device for producing hydrogen by dehydrogenating a hydrogenated organic substrate based on naphthenic hydrocarbons, comprising a hydrogenated organic substrate supply system, a flow reactor with a Pt / C catalyst in the form of granules or powder, a microwave resonator, a coaxial cable with a communication loop for exciting the resonator, a fiber-optic sensor that controls the temperature of the catalyst, a microwave power amplifier that sets the generator p, electrically tunable by the frequency of microwave electromagnetic oscillations in the band of the microwave power amplifier, a control sensor through a directional coupler and a detector section of the microwave power reflected from the entrance to the resonator, for automatic resonance tuning of the microwave resonator, an attenuator electrically controlled for regulation the output power of the microwave cavity and maintaining the optimum temperature of the catalyst, a software device for controlling the process in the required modes of hydrogen production.

The invention is illustrated in the drawings.

Figure 1 presents a diagram of a microwave device on the wave E ₀₁ for activation (microwave heating) of the catalyst and the entire catalytic system, as well as the structure and diagrams of the electric field in the resonator when using vibrations, for example, type E ₀₁₀ , determining the location of the heating object (catalyst ); figure 2 is a longitudinal section of a microwave device; figure 3 is a functional diagram of an automated microwave catalytic device.

As shown in FIGS. 1, 2, the microwave catalytic device comprises a coaxial cable 1, a reactor 2, shielding cylinders 3, a resonator 4, a catalyst 5, mobile pistons 6, a fiber optic sensor with inputs 7.

Figure 3 shows the remaining nodes of the microwave device, where 8 is the attenuator, 9 is the microwave electromagnetic oscillation generator, 10 is the microwave power amplifier, 11 is the coupler, 12 is the detector section, 13 is the software device, 14 is the fiber-optic temperature sensor , 15 - feed system of the organic substrate.

Microwave electromagnetic energy through a coaxial line (or cable) 1 with a communication loop is fed to the input of the resonator 4, in which reactor 2 is located symmetrically along the cavity axis in the maximum electric field (quartz tube 2 with a diameter of 14 × 11 mm). In the center of the tube in the gap between the shielding cylinders 3, which play the role of preliminary capacitive tuning of the resonator 4 to the resonant frequency, there is a catalyst 5 (15% Pt / C) in the form of granules or powder with a volume of about 5 ÷ 10 cm ³ . Mobile pistons 6 allow preliminary inductive tuning of the resonator to the resonant frequency.

To control the operating temperature of the catalyst 5 and the catalytic system in the resonator 4 (FIG. 2), inputs 7 are provided for the fiber optic temperature sensor 14 (FIG. 3), the feature of which is the high accuracy (1 ÷ 2 ° C) of measuring the temperature of the catalyst, the absence electrical interference during temperature registration in the microwave field and the invariance of the structure of the electromagnetic field.

At the inlet of reactor 2, an organic substrate based on perhydrogenated aromatic hydrocarbons continuously passes from the feed system 15 (FIG. 3): biphenyl or naphthalene, or anthracene, or mixtures thereof, or their functional derivatives and mixtures thereof, or an aromatic polymer containing polystyrene, or its copolymer, or polyacetylene, or polycumulene, preferably terphenyl.

The efficiency and speed of activation of a composite catalytic system by microwave heating is determined by the composition of the catalyst and the catalytic system as a whole, the presence and amount of hydrogen in the reactor, as well as the system for automatically maintaining the resonant frequency of the resonator E ₀₁₀ , which determines the efficiency of introducing microwave power into it, through monitoring the level of reflected Microwave power from the entrance to the resonator using a directional coupler 11 with the detector section 12 (figure 3) and maintaining a constant optimal operating temperature is catalyzed using the fiber-optic temperature sensor 14, which accurately measures the temperature of the catalyst and the catalytic system in the microwave field and maintains the optimal operating temperature of the process of efficient hydrogen evolution in the microwave electromagnetic field by adjusting the microwave power level using an electrically controlled attenuator 8 entering the resonator 4. (The optimum temperature of the catalytic system corresponds to the maximum rate of hydrogen evolution).

The method of producing hydrogen is as follows.

In the resonator 4 (Fig. 1, 2, 3) with the reactor 2 (Fig. 1, 2) (quartz tube with a diameter of 14 × 11 mm) filled with powder or pellets of the catalyst Pt / C 5, mainly 15% Pt / C, volume 5 ÷ 10 cm ³ is supplied to heat it from the master microwave power generator 9 (Fig. 3) through an electrically controlled attenuator 8 and a microwave power amplifier 10 with a microwave power of preferably 10 ÷ 20 W at a frequency of 5.6 ÷ 6.2 GHz or 20 -40 W at a frequency of 3.6 ÷ 4.0 GHz. Almost instantly (5 ÷ 10 seconds after applying microwave power), the microwave heating of the catalyst to a temperature of 170 ÷ 270 ° C is carried out. Temperature measurement is performed by a fiber-optic temperature sensor 14 (Fig. 3) directly in the microwave field. Then, a hydrogenated organic substrate, for example, perhydroterphenyl in a liquid-viscous state (after preheating), is introduced into the quartz tube inlet of reactor 2 through a feed system 15. In this case, the rate of hydrogen evolution can reach 0.25 ÷ 0.5 l / min at a temperature of the catalytic system in the range of 170 ÷ 270 ° C.

To stabilize the technological mode of operation of the microwave catalytic device, which provides a high rate of hydrogen evolution at a lower temperature of the catalytic system (170 ÷ 270 ° C), automatic feedback systems are used that ensure that the resonator operates in the resonant mode and the optimum temperature of the entire composite catalytic system (figure 3).

Automatic control of the hydrogen evolution technological process is carried out using a software device 13 according to a predetermined program using a resonator 4 resonance frequency control sensor (11 and 12) using a directional coupler 11 and a detector section 12 and catalyst temperature sensor 14 (Fig. 1, 2 ) and the catalytic system as a whole, as well as the sensor for controlling the flow of perhydroterphenyl (Fig. 3). According to a predetermined program, the device 13 automatically provides adjustment in the feed system 15 of the flow rate of the hydrogenated organic substrate (perhydroterphenyl or another reagent) and, in accordance with the change in the flow rate of the reagent, the microwave output of the amplifier 10 and its input efficiency through the coupler 11 and the detector section 12 are automatically adjusted resonator 4 to achieve the optimum temperature of the catalytic system and the maximum rate of hydrogen evolution.

The hydrogen production method can also be carried out by continuously feeding a hydrogenated catalytic suspension mixture containing a Pt / C catalyst, mainly 15% Pt / C 5, and perhydroterphenyl melt to the inlet of the reactor, made in the form of a quartz tube with a diameter of 14 ÷ 11 mm, located in the microwave -resonator 4, with a microwave power of 15 ÷ 20 W and a frequency of 5.6 ÷ 6.2 GHz. The catalytic suspension mixture is heated as it passes through the reactor 2 located in the microwave cavity 4 to a temperature of 170 ÷ 270 ° C and releases hydrogen at a rate of at least 0.5 l / min. When using a frequency of 3.6 ÷ 4.0 GHz, similar results can be obtained with a microwave power in the cavity of 30 ÷ 40 watts.

Examples of embodiments of the invention

Example 1

A hydrogenated catalytic system (total weight 10 g), consisting of 3 g of Pt / C catalyst, mainly 15% Pt / C, and molten perhydroterphenyl (7 g), is placed in the microwave resonator E ₀₁₀ coaxially to its axis in the region of maximum uniform electric field and excite the resonator with vibrations of the form ТМ _01ρ , where ρ is an integer equal to the number of half-waves stacking along the length of the resonator at a frequency of 6.0 GHz (resonance) in the amplifier band of 5.6 ÷ 6.2 GHz at a microwave power of 10 W introduced into the resonator. 10 seconds after the microwave power is supplied to the resonator, the catalytic system is heated to a temperature of 270 ° C, which is determined by the readings of the fiber-optic temperature sensor 14. The amount of hydrogen released and its release time are measured using a gas clock. The maximum hydrogen evolution rate in this example was 0.5 L / min.

Example 2

The same operations described in example 1, but for the microwave heating of the hydrogenated catalytic system, a frequency of 3.8 GHz is used (in the amplifier band 3.6 ÷ 4.0 GHz). In this case, to heat the catalytic system to 250 ° C, it takes 2 times more time (20 sec) when the microwave power of the amplifier is 4 times increased (40 W). The hydrogen evolution rate in this case was 0.25 L / min.

Example 3

Reactor 2 in the form of a quartz tube with a diameter of 14 ÷ 11 mm with 3 g of catalyst 15% Pt / C is placed in a microwave resonator with oscillations of the form E ₀₁₀ in the region of maximum uniform electric field at a microwave power of 15 W at a frequency of 6.0 GHz. 10 seconds after applying microwave power to the resonator, the catalyst is heated to a temperature of 270 ° C. Then, pre-heated to 60-100 ° C hydrogenated terphenyl in a liquid-viscous state is fed to the inlet of the quartz tube. In this case, depending on the supply rate of terphenyl, the rate of hydrogen evolution can reach 0.5-1.0 l / min.

Example 4

The same operations described in Example 3, but (unheated) perhydroterphenyl is fed at room temperature to the reactor inlet — a quartz tube with the same flow rate of the organic substrate — and the catalyst 15% Pt / C (3 g) is heated to a temperature of 170 ° C while the microwave power at a frequency of 6.0 GHz is 15 watts. In this case, the rate of hydrogen evolution at a certain feed rate of terphenyl can reach 0.25 l / min.

In all experiments (examples 1-4), the program unit 13 for a certain mass of catalyst placed in the reactor 2 sets the rate of hydrogen evolution, for which the program determines, based on the capabilities of the proposed microwave device (resonator with a quartz reactor), the required flow rate hydrogenated terphenyl (or a catalytic mixture of a 15% Pt / C catalyst and molten perhydroterphenyl), the microwave power for heating the catalyst and the entire composite catalyst system to a temperature of 170 -270 ° C for no more than 5-10 seconds.

Claims (7)

1. A method of producing hydrogen by dehydrogenating a hydrogenated organic substrate based on naphthenic hydrocarbons in contact with a catalyst containing platinum on a carbon support (Pt / C), in which, during the dehydrogenation process, the catalyst is heated in the electrodynamically matched resonance mode of the electromagnetic field of the microwave resonator excited oscillations of the form TM _{01, ρ} , where ρ is an integer, while the Pt / C catalyst is placed in a reactor made in the form of a quartz tube, which is arranged coaxially with microwave To the tenator in the region of maximum electric field. 2. The method according to claim 1, characterized in that the microwave resonator is excited from an electrically tunable microwave frequency generator in the band of the microwave power amplifier through a coaxial cable with a communication loop. 3. The method according to claim 1, characterized in that the heating of the catalyst in the microwave cavity is carried out to a temperature of 170 ÷ 270 ° C. 4. The method according to claim 1, characterized in that the power of the microwave cavity is measured using a coupler and a detector section. 5. The method according to claim 1, characterized in that the temperature of the catalyst is measured by a fiber optic temperature sensor. 6. The method according to claim 1, in which a heated organic substrate - hydrogenated terphenyl in a liquid-viscous state is continuously fed to the inlet of a reactor containing a Pt / C catalyst heated by a microwave resonator to 170 ÷ 270 ° C. 7. Device for producing hydrogen by dehydrogenation of a hydrogenated organic substrate based on naphthenic hydrocarbons, comprising a hydrogenated organic substrate supply system, a flow reactor with a Pt / C catalyst in the form of granules or powder, a microwave resonator, a coaxial cable with a coupling loop to excite a resonator, fiber - an optical sensor that monitors the temperature of the catalyst, a microwave power amplifier, a master oscillator that is electrically tunable according to the frequency of electromagnetic oscillations C H in the band of the power amplifier of the microwave resonator, a control sensor through a directional coupler and a detector section of the power of the microwave resonator reflected from the entrance to the resonator for automatic resonance tuning of the microwave resonator, an attenuator electrically controlled to control the output power of the microwave resonator and maintain optimal catalyst temperature, a software device for controlling the process in the required modes of hydrogen production.

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