EP4031280A1

EP4031280A1 - Catalytic assembly comprising a micrometric ferromagnetic material and use of said assembly for heterogeneous catalysis reactions

Info

Publication number: EP4031280A1
Application number: EP20820266.3A
Authority: EP
Inventors: Julien Marbaix; Sumeet KALE; Stéphane FAURE; Aikaterini Soulantika; Bruno Chaudret
Original assignee: Centre National de la Recherche Scientifique CNRS; Institut National des Sciences Appliquees de Toulouse
Current assignee: Centre National de la Recherche Scientifique CNRS; Institut National des Sciences Appliquees de Toulouse
Priority date: 2019-09-19
Filing date: 2020-09-18
Publication date: 2022-07-27
Also published as: FR3100990B1; FR3100990A1; US20230241588A1; WO2021053307A1; AU2020350156A1; JP2022549603A; CA3147684A1; CN114667187A

Abstract

The invention relates to a catalytic assembly for carrying out a heterogeneous catalysis reaction in a given temperature range T, characterized in that it comprises the association of at least one catalytic compound capable of catalyzing said reaction in the temperature range T and of a ferromagnetic material in the form of micrometric particles and/or wires, said ferromagnetic material being capable of being heated by magnetic induction by means of a field inductor. The invention also relates to the use of said catalytic assembly for implementing a heterogeneous catalysis reaction such as a methanation reaction.

Description

Title of the invention: Catalytic assembly comprising a micrometric ferromagnetic material and use of said assembly for heterogeneous catalysis reactions [0001] FIELD OF THE INVENTION

The present invention relates to the field of heterogeneous catalysis, in particular a catalytic assembly for carrying out a gas-solid heterogeneous catalysis reaction and its use for such catalysis reactions, in particular for hydrocarbon synthesis reactions. [0003] Gas-solid heterogeneous catalysis reactions involve contacting at least one gaseous reagent and a solid catalytic compound. These catalysis processes require a heating step, sometimes at high temperature, to carry out the reaction, and are therefore expensive and very energy-consuming. Research has therefore been oriented towards more economical solutions and in particular towards less energy-intensive reactions.

STATE OF THE PRIOR ART

[0005] Among these solutions, it has been proposed in the international application

WO201 4/162099 a heterogeneous catalysis process in which the heating is carried out by magnetic induction in order to reach the temperature necessary for the reaction. More particularly in this process, the reagent is brought into contact with a catalytic composition which comprises a ferromagnetic nano-particulate component, the surface of which consists at least in part of a compound which catalyzes said reaction, said nano-particulate component being heated by magnetic induction to achieve the desired temperature range. This heating can be carried out by means of a field inductor external to the reactor. In this system, the nanoparticles are heated by their own magnetic moment, allowing the catalyst to heat up and the catalytic reaction to start. Heating is therefore initiated within the reactor itself, rapidly with minimal energy input. This results in substantial savings. [0006] However, these ferromagnetic nanoparticles require significant heating power: for example between 1100 and 2100 W / g at 100 kHz for FeC nanoparticles (recent publication by Kale et al, Iron Carbide or iron carbide / cobalt nanoparticles for magnetically -induœd C02 hydrogenation over Ni / SiRAIOx catalysts, Catal. Sci. Technol., 2019, 9, 2601.

[0007] Furthermore, document WO2014 / 162099 insists on optimizing the size of nanometric particles and suggests a size of the ferromagnetic nano-particulate component of between 5 nm and 50 nm with an optimum size of 20 nm in the case of iron. . [0008] It therefore turns out that the cost of these reactions remains high, in particular because of the heating power required and the cost of the catalytic particles in nanometric form, in particular magnetic nanoparticles.

[0009] In addition, the nanometric size of these materials generally implies handling precautions.

Another problem associated with the use of nanoparticles is the modification of their heating properties due, on the one hand to their tendency to sinter during high temperature reactions, and on the other hand to aging resulting from a change in the chemical order in said nanoparticles (modification of the structure and of the local chemical composition).

[0011] AIMS OF THE INVENTION

[0012] A first object of the invention is therefore to overcome the aforementioned drawbacks by proposing a catalytic component making it possible to further reduce the cost of these heterogeneous catalysis reactions, while maintaining their reaction performance.

Another object of the invention is to provide a catalytic component making it possible to reduce the proportion of nanometric particles in the reactor.

Another object of the invention is to provide a catalytic component allowing the heating properties and the catalytic properties to be maintained over very long periods of time, while being suitable for intermittent operation. [0015] DESCRIPTION OF THE INVENTION

In the search for new savings, the inventors have discovered, surprisingly, that the heating agent may not necessarily be in nanometric form, but may be present in the reactor in the form of micrometric powder or of micrometric diameter wires. .

To this end, the present invention provides a catalytic assembly for carrying out a heterogeneous catalysis reaction in a given temperature range T, said catalytic assembly being characterized in that it comprises the combination:

- at least one catalytic compound formed from metal particles and capable of catalyzing said reaction in the temperature range T

- and at least one ferromagnetic material in the form of micrometric particles with a particle size between 1 mm and 1000 mm and / or wires based on iron or an iron alloy having a wire diameter between 1 mm and 1 mm, said ferromagnetic material being suitable for being heated by magnetic induction by means of a field inductor.

The examples presented later in the text show good energy efficiency of such a micrometric ferromagnetic material as a heating agent. In particular, the results obtained with such a heating agent which is no longer nanometric, but of much larger size, are equivalent to those obtained in the process of WO2014 / 162099.

[0019] According to a first embodiment of the invention, the catalytic assembly is in the form of a powder comprising a mixture of at least one catalytic compound in particulate form with micrometric particles of the ferromagnetic material.

As regards the micrometric particles of the ferromagnetic material, they advantageously have a particle size of between 1 mm and 100 mm, preferably between 1 mm and 50 mm, more preferably between 1 mm and 10 mm, that is to say say a size much greater than those of the nanoparticles described in document WO2014 / 162099. With such micrometric ferromagnetic particles, which admittedly sometimes tend to agglomeration, no sintering is observed and the efficiency of the heating is thus maintained.

Said catalytic compound can in particular be formed of metal particles (metal, metal oxide or a combination of the two) of catalyst arranged on the surface of an oxide forming the catalyst support, such as at least one oxide of the following elements : silicon, aluminum, titanium, zirconium, cerium, constituting a catalyst-oxide compound.

The catalyst support oxide can be for example Al2O3, SiO ₂ , TiO ₂ , ZrO ₂ , CeO ₂ constituting a catalyst-oxide compound in the form of a powder of micrometric or nanometric size which is mixed with the ferromagnetic material in the form of micrometric powder. The mixture of these powders (catalyst-oxide compound with the micro-particulate ferromagnetic material) thus creates intimate contact between the heating agent and the catalyst, making it possible to quickly start the catalysis reaction at the surface of the catalyst.

According to a second embodiment of the catalytic assembly of the present invention, the catalytic compound comprises metallic particles (in the form of metal, metal oxide or a combination of the two) of catalyst arranged on the surface of the ferromagnetic material occurring in the form of threads.

Advantageously, the ferromagnetic material in the form of son comprises iron wool containing son based on iron or an iron alloy, having a wire diameter between 10 micrometers and 1 millimeter, preferably between 20 mm and 500 mm, more preferably between 50 mm and 200 mm.

[0026] The ferromagnetic material is advantageously based on iron, or an iron alloy, comprising at least 50% by weight of iron, preferably comprising at least 80% by weight of iron.

The ferromagnetic material may in particular be composed of superfine iron wool, forming an entanglement of son composed of at least 90% by weight of iron, and whose diameter of the son may be between 50 mm and 100 mm. The metal catalyst particles of the catalytic compound can be chosen from manganese, iron, nickel, cobalt, copper, zinc, ruthenium, rhodium, palladium, iridium, platinum, l tin, or an alloy comprising one or more of these metals. Preferably, the metallic catalyst particles of the catalytic compound are particles of nickel or of ruthenium.

The present invention also relates to the use of the catalytic assembly described above for the implementation of a heterogeneous catalysis reaction comprising the contact, in a reactor, of at least one reagent with said. catalytic assembly and heating said ferromagnetic material by magnetic induction by means of a field inducer external to the reactor, so as to catalyze said reaction in the temperature range T.

Quite surprisingly, iron wool, a cheap and readily available material that can be purchased at DIY stores, has proven to be an excellent heating agent. More particularly, very fine iron wool (called superfine), having a wire diameter of less than one millimeter, is effective in allowing the heating of said catalyst by magnetic induction and can also be a good catalyst support. This material is very easy to use and has a very long lifespan. In addition, it is easily recoverable and is non-polluting.

The heterogeneous catalysis reaction is advantageously a hydrocarbon synthesis reaction, more particularly the heterogeneous catalysis reaction is a reaction of hydrogenation of a carbon monoxide in the gaseous state, such as a reaction of methanation from carbon dioxide and hydrogen.

Brief description of the drawings

The invention will be clearly understood on reading the following description of non-limiting embodiments with reference to the accompanying drawings in which:

[0034] [Fig. 1A] is a partial simplified diagram of a reactor for the use of a catalytic assembly according to the invention for a heterogeneous catalysis reaction gas-solid according to the invention, under an ascending gas flow, showing the positioning of the catalyst + heating agent assembly in the part of the tubular reactor surrounded by the external magnetic field inductor,

[0035] [Fig. 1 B] is a partial simplified diagram of a reactor for the use of a catalytic assembly according to the invention for a heterogeneous gas-solid catalysis reaction according to the invention, under a descending gas flow, showing the positioning of the catalyst + heating agent assembly in the part of the tubular reactor surrounded by the external magnetic field inductor,

[0036] [Fig. 2] is a graph comparing the performances of different ferromagnetic materials, carried out under argon at 100 kHz (specific absorption rate (noted SAR) corresponding to the quantity of energy absorbed per unit of mass, expressed in Watt per gram of material, depending on the intensity of the alternating magnetic field applied, expressed in mT): iron powder with microparticles of the order of 3-5 mm, fine iron wool (wire diameter greater than 1 mm) and straw superfine iron (wire diameter less than 1 mm, of the order of 100 mm),

[0037] [Fig. 3] is a graph showing the results of the use of a catalytic assembly according to the invention for a methanation reaction using iron powder as heating agent and a Ni catalyst on SiRAIOx® (oxide of silicon and aluminum from SESAL),

[0038] [Fig. 4] is a histogram showing the conversion rates (in%) of CO ₂ and CH _{4 as} well as the selectivity as a function of time and temperature for a downflow methanation reaction in the presence of a mixture of powder of iron and Ni / CeO ₂ ,

[0039] [Fig. 5] is a histogram showing the conversion rates (in%) of CO ₂ and CH _{4 as} well as the selectivity as a function of time and temperature for a downflow methanation reaction in the presence of a straw mixture of iron and Ni / CeO ₂ ,

[0040] [Fig. 6] is a histogram showing the conversion rates (in%) of CO ₂ and CH _{4 as} well as the selectivity as a function of time and temperature for a downflow methanation reaction in the presence of nickel on steel wool, [0041] [Fig. 7] is a comparative graph of the energy efficiency (expressed in%) as a function of the temperature of the three types of catalytic assemblies forming catalytic beds tested in the examples presented in FIGS. 4, 5 and 6.

[0042] EXAMPLES

Example 1: Preparation of the catalyst

Preparation of the catalyst on cerium oxide support

Nickel at 10% by mass on cerium oxide (abbreviated Ni (10wt%) / CeO ₂ ) is prepared by decomposing Ni (COD) 2 in the presence of CeO ₂ in mesitylene.

According to a conventional preparation process, 1560 mg of Ni (COD) 2 are dissolved in 20 mL of mesitylene and then 3 g of CeO ₂ are added. The mixture obtained is heated at 150 ° C. under an argon atmosphere for 1 hour with vigorous stirring. This mixture, initially milky white, is black at the end of the reaction. After decantation, the translucent supernatant is removed and the particles obtained are washed three times with 10 ml of toluene. The toluene is then removed under vacuum, making it possible to obtain a thick Ni10wt% / CeO ₂ powder (3.5 g) which is collected and stored in a glove box. Analysis by inductively coupled plasma mass spectroscopy (ICP-MS) confirms the loading of 9% by mass of nickel (10% target) of the cerium oxide. Observation by transmission electron microscopy (TEM) and EDS analysis show the presence of small monodisperse nickel particles (2-4 nm in size).

Process for preparing Ni on SiRAIOx®

In a Fischer-Porter bottle and under an inert atmosphere, 0.261 g of Ni (COD) 2 are dissolved in 20 mL of mesitylene and 0.500 g of SiRAIOx® are added. The mixture is heated at 150 ° C. for one hour with stirring. After returning to ambient temperature, the powder is allowed to precipitate, then the supernatant is removed and the powder is washed three times with 10 ml of THF. The powder is then dried under vacuum and stored under an inert atmosphere.

Powder mixture of iron + Ni / Ce02

2 g of powdered iron are mixed with 1 g of nickel catalyst deposited on the cerium oxide prepared previously. Observation under a scanning electron microscope as well as EDS mapping make it possible to visualize grains of iron powder with a size of about 3-5 mm and to confirm that the nickel is indeed present on the cerium oxide CeO ₂ .

Example 2: Preparation of the catalyst on an iron wool support

Superfine iron straw (Gerlon, purchased from Castorama). ICP-MS analysis of superfine iron wool yields a composition of 94.7% by weight of iron. EDS mapping shows the presence of numerous impurities on the surface of the straw (mainly potassium, manganese, silicon). The SEM observation makes it possible to determine the diameter of the wires of the superfine steel wool used which is about 100 mm and has a rough and irregular surface.

The experimental protocol for depositing metallic nickel on superfine iron wool (entanglement of wires of about 100 mm in diameter, at 94.7% by weight of iron) is substantially the same as on Ce02. 1560 mg of Ni (COD) 2 are dissolved in 100 mL of mesitylene in order to completely immerse the steel wool (3 g). After one hour with vigorous stirring at 150 ° C. under argon, the mixture is placed in a glove box and the solution (black in color) is discharged. The steel wool also turned black. The steel wool is then rinsed with toluene, then dried under vacuum for 30 minutes and stored in a glove box. Observation by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy show the deposition of polydisperse nickel particles (100nm-1000nm) on the surface of the wires of the steel wool.

The ICP-MS analysis on three different zones shows different nickel loadings: 1.23%, 1.44% and 1.33% (mass percentages). These differences between these loadings are quite small, the surface of the straw seems homogeneous. Despite everything, the quantity of nickel deposited is below the percentage of 10% by mass of Ni targeted.

Example 3: methanation reaction: conversion measurements and calculation of the selectivity

The methanation reaction

[0054] [Chem. 1] [0055] which is a combination of

[0056] [Chem. 2]

[0057] and

[0058] [Chem. 3]

Is carried out in a continuous tubular reactor 1 with a fixed bed and quartz (Avitec) (internal diameter: 1 cm with a height of catalytic bed 4, depending on the heating element, of about 2 cm, resting on glass sintered 3) (see figure 1); the gas stream can be upward flow 6 (Fig.lA) or downward flow 7 (Fig.1 B)). The coil 2 (from the company Five Celes) used is a solenoid with an internal diameter of 40 mm and a height of 40 mm constituting the external magnetic field inductor connected to a generator. Its resonant frequency is 300 kHz with a magnetic field varying between 10 and 60 mT. Coil 2 is water cooled.

The measurements of the conversion rate and of the selectivity as a function of the temperature are carried out with temperature control of the generator associated with the coil 2. For this purpose, a temperature probe 5 connected to the generator is immersed in the bed catalytic (together heating agent + catalyst). The generator sends a magnetic field to reach the set temperature and then sends only pulses to maintain that temperature. The reaction takes place at atmospheric pressure and at a temperature varying between 200 and 400 ° C. Reactor 1 is supplied with H ₂ and CO ₂ , the flow rate of which is controlled by a flowmeter (Brooks flowmeter) and controlled by Lab View software. The proportions are as follows: an overall constant flow rate of 25 mL / min comprises 20 mL / min of H ₂ and 5 mL / min of CO ₂ . The feed is made at the head of the reactor, the water formed is condensed at the bottom of the reactor (without condenser) and is recovered in a flask. The methane formed and the remaining gases (CO ₂ and H ₂ ) as well as the CO are sent to a gas chromatography column (GC Perkin Elmer column, Clarus 580). The conversion of CO ₂ , the selectivity of CH ₄ and the yield of CO and CH ₄ are calculated according to the following equations

[0061] [Math. 1] FC is the response factor for each reagent according to reaction monitoring by gas chromatography, A is the area of the peak measured by chromatography.

[0063] Energy efficiency measures:

Energy efficiency measurements are carried out in parallel with the conversion and selectivity measurements of the methanation reaction. The electrical consumption data for coil 2 is retrieved using software developed in the laboratory. Energy efficiency is then calculated as follows

[0064] [Math. 2]

PCS (higher caloric value) represents the amount of energy released by the combustion of 1 mg of gas, the values given by the literature are PCSH2 = 141.9 MJ / kg and PCSCH ₄ = 55.5 MJ / kg ,

Y CH4 being the yield of the reaction in CH ₄ ,

Dmi the mass flow of product i,

Coil corresponds to the energy consumed by the inductor to operate (at know, generate the magnetic field and cool the system),

Energy efficiency is expressed in% in Figure 7.

[0066] Example 4: Comparison of Different Ferromagnetic Materials as Heating Agents [0067] Iron powder, fine iron wool and fine iron wool were compared. Measurements of the specific absorption rate (SAR) (corresponding to the amount of energy absorbed per unit mass, expressed in Watts per gram of material), as a function of the intensity of the applied alternating magnetic field, expressed in mT) were performed at 100 kHz under argon. The results are grouped together in Figure 2.

These results differ significantly from those obtained in the recent publication by Kale et al, Iron Carbide or iron carbide / cobalt nanoparticles for magnetically-induced CO ₂ hydrogenation over Ni / SiRAIOx catalysts, Catal. Sci. Technol., 2019, 9, 2601., which reports for FeC nanoparticles SAR values of between 1100 and 2100 W / g at 100 kHz. Figure 2 shows that for a micro-particulate ferromagnetic material such as iron powder or steel wool these values are 10 to 20 times lower.

We could then expect to have to provide the micro particulate iron powder and the steel wool with a greater field than for the nanoparticles. But the results in Figure 3 show that this is not the case. For iron carbide nanoparticles, it is necessary to provide a field of around 48 mT to achieve a yield close to 90%. With iron powder, after starting the reaction, a field of only 8 mT is required. The peculiarity of iron powder and steel wool lies in the eddy currents that come into play and cause a decrease in the magnetic field to heat the material.

The iron powder and the micrometric iron wool therefore constitute interesting ferromagnetic materials for heating in situ by magnetic induction the reactors implementing gas-solid catalytic reactions such as methanation reactions from carbon dioxide and carbon dioxide. dihydrogen, which is presented in the examples which follow. Example 5: Catalytic assembly: mixture of iron powders and catalyst

The catalytic bed consists of particles of nickel on cerium oxide:

Ni: 0.09 g / CeO ₂ : 0.91 g, mixed with 2 g of iron powder. The gas flow is downward, at a constant flow rate of 20 mL / min of H ₂ and 5 mL / min of CO ₂ .

The results of the CO ₂ and CH ₄ conversion rates are shown in FIG. 4. This set of powders (iron powder + Ni / CeO ₂ ) makes it possible to obtain very high yields (Y (CH ₄ )). satisfactory, reaching 100% at temperatures of 300-350 ° C.

Example 6: Catalytic assembly: mixture of iron wool and Ni / CeO 2 catalyst

The catalytic bed consists of nickel particles deposited on cerium oxide: Ni: 0.09 g / CeO ₂ : 0.91 g and of 0.35 g of superfine iron wool. The gas flow is downward, at a constant flow rate of 20 mL / min of H ₂ and 5 mL / min of CO ₂ .

The results of the CO ₂ and CH ₄ conversion rates are shown in FIG. 5. This set of iron wool + Ni / Ce02 also makes it possible to obtain _{very satisfactory yields (Y (CH 4} )), reaching 100% at temperatures of 300-350 ° C.

Example 7: Catalytic assembly: Ni deposited on steel wool

The catalytic bed consists of particles of nickel: Ni: 0.03 g deposited on 2.27 g of superfine iron wool. The gas flow is downward, at a constant flow rate of 20 mL / min of H ₂ and 5 mL / min of CO ₂ .

The results of the CO ₂ and CH ₄ conversion rates are shown in FIG. 6. The maximum yield (Y (CH ₄ )) is 90% at 400 ° C. This result is very encouraging given that this system is the simplest to implement.

[0080] Example 8: Energy efficiency

The energy efficiency calculations of the three preceding examples (examples 5, 6 and 7) grouped together in FIG. 7 show that less energy must be supplied to the catalytic assembly comprising the steel wool than to the 'catalytic assembly comprising the iron powder to reach the same temperature. This The difference between powder and straw is observed especially with the steel wool + Ni / Ce02 system. The energy efficiency of the iron straw + Ni catalytic assembly is not as good because there is more straw to heat and therefore more energy to supply for the same quantity of methane produced. In the example presented, it was necessary to introduce a greater quantity of steel wool, because very little nickel had been deposited therein, to achieve an interesting yield (90%).

Claims

[Claim 1] Catalytic assembly for carrying out a heterogeneous catalysis reaction in a given temperature range T, characterized in that it comprises the association of at least one catalytic compound formed from metal particles and capable of catalyzing said reaction in the temperature range T and of a ferromagnetic material in the form of micrometric particles with a particle size between 1 mm and 1000 mm and / or wires based on iron or an iron alloy having a wire diameter between 1 mm and 1mm, said ferromagnetic material being capable of being heated by magnetic induction by means of a field inductor.

[Claim 2] Catalytic assembly according to claim 1, characterized in that it is in the form of a powder comprising a mixture of at least one catalytic compound in particulate form with micrometric particles of the ferromagnetic material.

[Claim 3] Catalytic assembly according to one of claims 1 or

2, characterized in that the micrometric particles of the ferromagnetic material have a particle size of between 1 mm and 100 mm, preferably between 1 mm and 50 mm, more preferably between 1 mm and 10 mm.

[Claim 4] Catalytic assembly according to one of claims 1 to

3, characterized in that said catalytic compound is formed of metal catalyst particles arranged on the surface of an oxide forming a catalyst support, such as an oxide of the following elements: silicon, aluminum, titanium, zirconium, cerium, constituting a catalyst-oxide compound.

[Claim 5] Catalytic assembly according to Claim 1, characterized in that the catalytic compound comprises metallic catalyst particles arranged on the surface of the ferromagnetic material in the form of wires.

[Claim 6] A catalytic assembly according to claim 5, characterized in that the ferromagnetic material in the form of wires comprises iron wool containing wires based on iron or a iron alloy, having a wire diameter of between 20 mm and 500 mm, preferably between 50 mm and 200 mm.

[Claim 7] Catalytic assembly according to any one of the preceding claims, characterized in that the ferromagnetic material is based on iron or an iron alloy, preferably comprising at least 50% by weight of iron, more preferably less 80% by mass of iron.

[Claim 8] Catalytic assembly according to any one of claims 1, 5 or 6, characterized in that the ferromagnetic material is composed of superfine iron wool, comprising an entanglement of threads composed of at least 90% by weight of iron, and whose wire diameter is between 50mm and 100mm.

[Claim 9] Catalytic assembly according to any one of claims 4 or 5, characterized in that the metallic catalyst particles of the catalytic compound are chosen from manganese, iron, nickel, cobalt, copper, zinc, ruthenium, rhodium, palladium, iridium, platinum, tin, or an alloy comprising one or more of these metals.

[Claim 10] Catalytic assembly according to al claim 9, characterized in that the metallic catalyst particles of the catalytic compound are particles of nickel or ruthenium.

[Claim 11] Use of the catalytic assembly according to any one of the preceding claims for carrying out a heterogeneous catalysis reaction comprising bringing into contact, in a reactor (1), at least one reagent with said catalytic assembly and heating said ferromagnetic material by magnetic induction by means of a field inducer external to the reactor, so as to catalyze said reaction in the temperature range T.

[Claim 12] Use according to claim 11, characterized in that the heterogeneous catalysis reaction is a hydrocarbon synthesis reaction.

[Claim 13] Use according to any one of claims 11 or 12, characterized in that the heterogeneous catalysis reaction is a hydrogenation reaction of a carbon monoxide in the gaseous state, such as a methanation reaction from carbon dioxide and hydrogen.