EP3558518A1

EP3558518A1 - Macroporous oxygen carrier solid with a refractory feldspar/felpdspathoid, method for the preparation thereof, and use thereof in a chemical-looping oxidation-reduction method

Info

Publication number: EP3558518A1
Application number: EP17838128.1A
Authority: EP
Inventors: Arnold Lambert; Catherine Laroche; Delphine Marti; Elodie COMTE
Original assignee: IFP Energies Nouvelles IFPEN; Total Raffinage Chimie SAS
Current assignee: IFP Energies Nouvelles IFPEN; TotalEnergies Onetech SAS
Priority date: 2016-12-23
Filing date: 2017-12-21
Publication date: 2019-10-30
Also published as: FR3061037A1; AU2017383046A1; FR3061037B1; CN110214055A; CN110214055B; US11071971B2; WO2018115345A1; US20190381488A1; CA3045289A1

Abstract

The invention relates to an oxygen carrier solid, its preparation and its use in a method of combustion of a hydrocarbon feedstock by active mass chemical-looping oxidation-reduction, i.e. chemical-looping combustion (CLC). The solid, which is in the form of particles, comprises an oxidation-reduction active mass composed of metal oxide(s) dispersed in a ceramic matrix comprising at least at least one feldspar or feldspathoid with a melting point higher than 1500°C, such as celsian, and has, initially, a specific macroporous texture. The oxygen carrier solid is prepared from a precursor of the ceramic matrix, obtained from a macroporous zeolitic material with zeolite crystals of a specific size, and a precursor of the oxidation-reduction active mass.

Description

MACROPOROUS OXYGEN SOLID CARRIER WITH REFRACTORY FELDSPATH / FELPDSPATHOID, PREPARATION METHOD THEREOF, USE THEREOF

DOXYDO-CHEMICAL LOOP REDUCTION PROCESS

Field of the invention

The present invention relates to an oxygen carrier solid, its preparation and its use in an oxidation-reduction process in chemical loop on active mass, commonly known as "Chemical Looping" according to the English terminology. In particular, the new type of oxygen carrier solid according to the invention can be used in a chemical looping combustion process (Chemical Looping Combustion). General context

Chemical mass-based oxidation-reduction processes are known in the field of energy production, gas turbines, boilers and furnaces, particularly for the oil, glass and cement industry.

In particular, the production of electricity, heat, hydrogen or steam can be achieved by this type of process, typically the CLC process, implementing oxidation-reduction reactions of an active mass, called mass oxidation reduction, conventionally a metal oxide, to produce a hot gas from a fuel, for example natural gas, carbon monoxide CO, hydrogen H ₂ , coals or petroleum residues, a mixture of hydrocarbons, and isolate the carbon dioxide CO2 produced. It is then possible to store the C0 ₂ captured in geological formations, or to use it as a reagent in other processes, or to inject it into the oil wells in order to increase the quantity of hydrocarbons extracted from deposits (enhanced recovery of EOR oil and EGR gas, for "Enhanced Oil Recovery" and "Enhanced Gas Recovery").

In such a process of oxidation-reduction in chemical loop on active mass, a first reaction of oxidation of the active mass with air or another oxidizing gas, playing the role of oxidant, allows, because of the exothermic nature oxidation, to obtain a hot gas whose energy can then be exploited. When the oxidizing gas is water vapor, the oxidation of the active mass also makes it possible to produce a gaseous effluent rich in H ₂ .

A second reduction reaction of the oxidized active mass with the aid of a gas, a liquid or a reducing solid (hydrocarbon feedstock) then makes it possible to obtain a reusable active mass and a gaseous mixture comprising essentially CO2 and water, even

FIRE I LLE OF REM PLACEM ENT (RULE 26) synthesis gas containing CO and ΙΉ ₂ , depending on the conditions operated during the reduction step.

In a CLC process, the energy can be produced in the form of steam or electricity for example. The heat of combustion of the hydrocarbon feedstock is similar to that encountered in conventional combustion. This corresponds to the sum of the heats of reduction and oxidation in the chemical loop. The heat is generally extracted by exchangers located inside, wall or appendage of the fuel and / or air reactors, on the flue lines, or on the transfer lines of the active mass.

A major advantage of these oxidation-reduction processes in chemical loop on active mass is then to allow to easily isolate the CO ₂ (or synthesis gas) contained in the gaseous mixture without oxygen and nitrogen constituting the effluent from the reduction reactor. Another advantage is the production of a flow of nitrogen N ₂ (and argon) containing almost no oxygen, and corresponding to the effluent from the oxidation reactor, when the air is used as oxidizing gas. In a context of increasing global energy demand, the CLC process thus provides an attractive solution for C0 ₂ capture with a view to its sequestration or recovery for other processes, in order to limit the emission of greenhouse gases. greenhouse that is detrimental to the environment.

US Pat. No. 5,447,024 for example describes a CLC process comprising a first reactor for reducing an active mass using a reducing gas and a second oxidation reactor for restoring the active mass in its oxidized state by an oxidation reaction with moist air. The circulating fluidized bed technology is used to allow the continuous passage of the active mass of the reduction reactor to the oxidation reactor and vice versa. Patent application WO 2006/123925 describes another implementation of the CLC process using one or more fixed-bed reactors containing the active mass, the redox rings being carried out by permutation of the gases in order to successively carry out the oxidation and reduction of the active mass.

The active mass, passing alternately from its oxidized form to its reduced form and vice versa, describes an oxidation-reduction cycle. It should be noted that, in general, the terms oxidation and reduction are used in relation to the respectively oxidized or reduced state of the active mass. The oxidation reactor is one in which the active mass is oxidized and the reduction reactor is the reactor in which the active mass is reduced. Thus, in the reduction reactor, the active mass, usually a metal oxide (M _x Oy) is first reduced to the state M _x O _y 2n-m / 2, via a hydrocarbon C _n H _m , which is correlatively oxidized to C0 ₂ and H ₂ 0, according to reaction (1), or optionally in CO + H ₂ mixture according to the nature of the active mass and the proportions used.

C _n H _m + M _x O _y n C0 ₂ + m / 2 H ₂ 0 + M _x O _y-2n - _{m / 2} (1) In the oxidation reactor, the active mass is restored to its oxidized state ( M _x O _y ) in contact with the air according to reaction (2), before returning to the first reactor.

M _x O _{y-2n-m / 2} + (n + m / 4) 0 ₂ → M _x O _y (2)

In the case where the oxidation of the active mass is carried out by the steam, a flow of hydrogen is obtained at the outlet of the oxidation reactor (reaction (3)). M _x O _y-2n -m / 2 + (2n + m / 2) H ₂ 0 - »M _x O _y + (2n + m / 2) H ₂ (3)

In the equations above, M represents a metal.

The active mass has a role of oxygen carrier in the chemical loop redox process. Thus commonly referred to as solid oxygen carrier solid comprising the active mass, typically comprising the metal oxide or oxides capable of exchanging oxygen under the redox conditions of the oxidation-reduction process in a chemical loop.

The oxygen carrier solid may further comprise a binder or a support in association with the active mass, in particular to ensure good reversibility of oxidation and reduction reactions, and improve the mechanical strength of the particles. Indeed, the active masses, chosen, for example, from the redox couples of copper, nickel, iron, manganese and / or cobalt, are generally not used in pure form since the successive oxidation / reduction cycles at high temperature lead to a significant and rapid decrease in the oxygen transfer capacity, due to the sintering of the particles. Thus, in US Pat. No. 5,447,024, the oxygen carrier solid comprises a NiO / Ni redox couple as an active mass, associated with a YSZ binder which is yttrium-stabilized zirconia, also called yttria zirconia.

Many types of binders and supports, in addition to yttria YSZ zirconia, have been studied in the literature to increase the mechanical strength of particles at a lower cost than YSZ. Among these, mention may be made of alumina, spinel of aluminate metal, titanium dioxide, silica, zirconia, ceria, kaolin, bentonite, etc.

The effectiveness of the oxidation-reduction process in a chemical loop depends mainly on the physicochemical properties of the oxygen-carrying solid. In addition to the reactivity of the active mass involved and the oxygen transfer capacity of the oxygen-carrying solid (active mass + binder / support), which affect the design of the reactors and, in the case of bed technology circulating fluidized, on particle circulation rates, the lifetime of the particles in the process has a preponderant impact on the operating cost of the process, particularly in the case of circulating fluidized bed process. In fact, in the case of the circulating fluidized bed process, the attrition rate of the particles makes it necessary to compensate for the loss of oxygen-carrying solid in the form of fines, typically particles of the oxygen-carrying solid with a diameter of less than 40. μηη, with new oxygen carrier solid. The rate of renewal of the oxygen-carrying solid therefore strongly depends on the mechanical strength of the particles as well as their chemical stability under the process conditions, which includes many successive oxidation / reduction cycles.

In general, the performance of oxygen-carrying solids reported in the literature is satisfactory in terms of oxygen transfer capacity and reactivity with the various hydrocarbons tested (Adanez, J., Abad, A., Garcia- Labiano, F., Gayan, P. & Diego, LF, "Progress in Chemical Looping Combustion and Reforming Technologies," Progress in Energy and Combustion Science, 38 (2), (2012) 215-282). However, in most publications, too short a test period and / or the lack of thorough characterization of the particles after the test do not allow to conclude as to the lifetime of the particles in the CLC process, although some authors announce important lifetimes. Some recent studies highlight the problem of the lifetime of particles related to the many redox cycles suffered by the particles in the CLC process. For example, the problem of the lifetime of ilmenite particles (ore FeTiO ₃ ) has recently been demonstrated by P. Knutsson and C. Linderholm ("Characterization of the use of Oxygen Carrier in a 100 kW Chemical Looping"). Combustor for Solid Fuels ", 3rd International Conference on Chemical Looping, September 9-1, 2014, Gothenburg, Sweden). After a long-term test in a 100kWth circulating fluidized bed pilot, the SEM characterization of the aged particles shows that a high porosity has developed within the particles, which results in their disintegration as fines which are eliminated. in gas / solid separation cyclones. The porosity of ilmenite ore particles increases strongly with redox cycles and results in their sputtering, potentially challenging the adequacy of this ore to the process, while early studies on the use of ilmenite concluded at its conclusion. good suitability for the CLC process. The increase in porosity observed by the minute characterization of the particles after the test is concomitant with the migration of ferrous and / or ferric ions by diffusion within the particles. According to the authors, segregation of iron within the particles precedes its migration to the surface, creating the porosity that results in the disaggregation of the particles in the form of fines. The appearance of porosity is the main mechanism for the formation of fine particles during the process, considerably limiting the lifetime of the particles, and therefore the potential value of the ore for the CLC application. Indeed, the estimated lifespan of ilmenite particles is of the order of only 200 hours ("Emerging C0 ₂ Capture Systems", JC Abanades, B. Arias, A. Lyngfelt, T. Mattisson, DE Wiley, H Li, MT Ho, E. Mangano, S. Brandani, J. Int Greenhouse Gas Control 40 (2015), 126). The attrition phenomenon of the oxygen-carrying solid is thus mainly due to a morphological evolution linked to the consecutive redox cycles experienced by the particles rather than to shocks on the walls and between particles, usually considered as the main source of attrition in fluidized bed processes.

Wei et al. (Continuous Operation of a 10 kWth Chemical Looping Integrated Fluidized Bed Reactor for Gasifying Biomass Using an Iron-Based Oxygen Carrier, Energy Fuels 29, 233, 2015) also mention the conversion of synthetic Fe ₂ O ₃ / Al ₂ O ₃ particles. ₃ (70/30) in small grains (ie spraying of particles into fines) after only 60 hours of combustion in a circulating fluidized bed.

LS Fan et al. ("Chemical-Looping Technology Platform", AIChE J. 61, 2, 2015) state that the lack of demonstration of the CLC process on an industrial scale is related to the inadequacy of oxygen-carrying solids in terms of reactivity, recyclability, oxygen transfer capacity, mechanical strength and attrition resistance. According to these authors, the first studies on the oxygen-carrying solids did not realize the importance of the cationic and anionic migration mechanisms within the particles, which lead to phase segregations, the appearance of cavities or micropores, agglomeration, sintering, etc.

The patent application WO 2012/155059 discloses the use of oxygen carrier solids consisting of an active mass (20 to 70% by weight), a primary support material of the ceramic or clay type (5 to 70% by weight). , and a secondary support material (1 to 35% by weight), also of ceramic or clay type. An improved mechanical stability related to the control of the volume expansion is advanced for these solid oxygen carriers. It is explained that a diffusion movement of the iron ions towards the outside of the particles causes the volume expansion of the particles, which leads to embrittlement of the particles. In the solid according to WO 2012/155059, the primary support material would make it possible to disperse the metallic active mass and prevent its agglomeration, preserving the redox activity, whereas the secondary support material would serve to reduce the speed of volume expansion by forming a phase stabilizing solid that would prevent iron migration to the surface.

The numerous studies on a metal oxide (active mass generally based on Cu, Ni, Co, Fe and / or Mn oxide) on a support conclude that most of the formulations tested in the CLC process are suitable. However, Forero et al. (CR Forero, P. Gayân, F. Garcia-Labiano, LF de Diego, A. Abad, J. Adânez, Int.J. Greenhouse Gas Control 5 (201 1) 659-667) report a loss of copper oxide important, probably due to the migration of the active phase outwards of particles during redox cycles. Surface copper is then removed in the fines by attrition. In addition, the porosity of the CuO / Al ₂ O ₃ particles increases with the number of cycles, and the aluminum matrix is gradually cracking, resulting in the formation of fine particles. Adanez-Rubio et al. (Energy Fuels 2013 (27) 3918) report that the packed packed density of batches of CuO-based particles impregnated on different supports (Ti0 ₂ , Si0 ₂ , MgAl ₂ 0 ₄ ) decreases significantly, which can be attributed to to a significant increase in the porosity of the particles and means that the lifetime of these particles is limited.

The migration of the metal with the number of cycles is also encountered with Fe ₂ O ₃ / Al ₂ O ₃ particles, as reported by LS Fan et al. ("lonic diffusion in the oxidation of Iron-effect of support and its implications for chemical looping applications "Energy Environ., Sci., 4, 876, 201 1).

Lyngfelt et al. performed a 1000h test with nickel-based particles (40% NiO / 60% NiAl ₂ O ₄ ) in a 10kWth circulating fluidized bed plant (Linderholm, C., Mattisson, T. & Lyngfelt, A., "Long-term integrity testing of spray-dried particles in a 10-kW chemical-looping combustor using natural gas as fuel", Fuel, 88 (1 1),

(2009) 2083-2096). The authors conclude that the lifetime of the particles is of the order of 33000h, but a fairly high proportion of agglomerates is observed at the end of the test and part of the solid adhered to the walls of the reactor. The presence of metallic nickel on the surface of the particles, due to the migration of nickel outwards, is probably at the origin of the formation of the agglomerates observed (Jerndal, E., Mattisson, T., ThijsJ., Snijkers, F. & Lyngfelt, A., "Investigation of NiO / NiAl ₂ 0 ₄ Oxygen Tanks for chemical-looping combustion produced by spray-drying", International Journal of Greenhouse Gas Control, 4,

(2010) 23). Such agglomerates represent a significant risk of accidental shutdown of the CLC process. In addition, the characterization of the aged particles is insufficient to really conclude the interest of this solid for the CLC. Batchwise fluidized bed tests on particles of a similar carrier, carried out by the applicants, show a large migration of nickel towards the periphery of the particles and the formation of fine particles (0.1 to 5 m in size) consisting essentially of nickel on the surface of large particles. The particles tested are initially purely mesoporous.

The search for a high-performance oxygen carrier, in terms of oxygen transfer capacity, reactivity with the various hydrocarbon feeds that can be treated, and mechanical strength, therefore remains a primary objective for the development of the processes. oxidation reduction in a chemical loop, such as CLC. Objectives and summary of the invention

The present invention aims to overcome the problems of the prior art described above, and generally aims to provide an oxygen carrier solid for a chemical loop redox process which has a long life when its use in the process, in particular to reduce investment costs and / or operation for such processes. Thus, to achieve at least one of the aforementioned objectives, among others, the present invention provides, in a first aspect, a particulate oxygen carrier solid for a method of combustion of a hydrocarbon feedstock by oxido. chemical loop reduction, comprising: an oxidation-reduction active mass constituting between 5% and 75% by weight of the oxygen-carrying solid, the oxidation-reduction active mass comprising a metal oxide or a mixture of metal oxides and being capable of carrying oxygen in the chemical-loop oxidation-reduction combustion process;

a ceramic matrix in which the oxidation-reduction active mass is dispersed, the ceramic matrix constituting between 25% and 95% by weight of the oxygen-carrying solid, and the ceramic matrix comprising between 60% and 100%; % by weight of at least one feldspar or feldspathoid having a melting temperature above 1500 ° C and between 0% and 40% of at least one oxide;

a porosity such that: the total pore volume of the oxygen-carrying solid, measured by mercury porosimetry, is between 0.05 and 0.9 ml / g,

the pore volume of the macropores constitutes at least 10% of the total pore volume of the oxygen-carrying solid;

the size distribution of the macropores within the oxygen carrier solid, measured by mercury porosimetry, is between 50 nm and 7 μηη.

Preferably, the total pore volume of the oxygen-carrying solid is between 0.1 and 0.5 ml / g.

The total pore volume of macropores constituting macropores constitutes at least 50% of the pore volume at least 50% of the pore volume of the oxygen-bearing solid. Preferably, the size distribution of the macropores within the oxygen-carrying solid is between 50 nm and 4 μηη.

The oxidation-reduction active mass preferably comprises at least one metal oxide included in the list consisting of Fe, Cu, Ni, Mn and / or Co oxides, a perovskite with redox properties, preferably a perovskite of formula CaMnO ₃ , a metal aluminate spinel having redox properties, preferably a metal aluminate spinel of formula CuAl ₂ O ₄ or a Cuprospinelle of formula CuFe ₂ O ₄ .

According to one embodiment of the invention, the oxidation-reduction active mass comprises at least one copper oxide.

Advantageously, said at least one feldspar or feldspathoid has a melting temperature greater than 1700 ° C.

Advantageously, said at least one feldspar or feldspathoid of the ceramic matrix is a feldspar chosen from the list consisting of celsiane, slawsonite, anorthite, or a feldspathoid being kalsilite, and is preferably celsiane.

Said at least one oxide of the ceramic matrix may be chosen from the list consisting of alumina, metal aluminates, silica, silicates, aluminosilicates, titanium dioxide, perovskites and zirconia.

Preferably, the particles have a particle size such that more than 90% of the particles have a size of between 50 μηη and 600 μηη.

According to a second aspect, the invention relates to a process for preparing the oxygen-carrying solid according to the invention, comprising the following steps:

(A) preparing a precursor of a ceramic matrix comprising:

a1) the preparation of a macroporous zeolite material, the macroporous zeolite material comprising zeolite crystals with a mean diameter of less than or equal to 3 μηη, and preferably a number-average diameter of between 0.4 μηη and 2 μηη; ; and

a2) a cationic exchange of said macroporous zeolite material with a solution of precursor ions, the precursor ions being chosen to form a feldspar or feldspathoid with a melting point> 1500 ° C. of the ceramic matrix at the end of the step ( D), the cationic exchange being followed by a washing of said macroporous zeolite material, to obtain the precursor of the ceramic matrix; (B) impregnating said precursor of the ceramic matrix obtained in step (A) with a precursor compound of an oxidation-reduction active mass;

(C) forming particles of the precursor of the ceramic matrix during step (a1) or at the end of step (B); (D) drying the precursor of the impregnated ceramic matrix in particle form obtained at the end of all of the steps (A), (B) and (C); and

(E) calcining the precursor of the impregnated and dried ceramic matrix obtained in step (D) to obtain the particulate oxygen carrier solid.

According to one embodiment, step a1) comprises: - a'1) agglomeration of the zeolite crystals with a clay binder to form a zeolite agglomerate;

- a'2) the shaping of the zeolite agglomerate obtained in step a'1) to produce particles, followed by drying of said particles, and possibly followed by a sieving and / or cycloning step ; - a'3) calcining the particles of the zeolite agglomerate obtained in step a'2) at a temperature between 500 ° C and 600 ° C to produce the macroporous zeolite material in particulate form;

- a'4) optionally the zeolitization of the clay binder by contacting the product resulting from step a'3) with an alkaline basic aqueous solution, followed by washing.

Advantageously, the zeolitic crystals comprise at least one zeolite with an Si / Al molar ratio of between 1.00 and 1.5, preferably zeolitic crystals comprising at least one zeolite chosen from zeolites A, X, LSX and low-silica EMT. EMT low-silica having a Si / Al ratio of between 1.0 and 1.4. According to one embodiment, the cation exchange in step a2) is carried out with a solution comprising alkaline ions, preferably K +, or alkaline earth ions, and preferably with a solution comprising alkaline earth ions. Preferably, the cationic exchange in step a2) is carried out with a solution comprising ions chosen from Ba ²⁺ , Sr ^{2 "} -, Ca ²⁺ ions, and preferably with a solution containing Ba ²⁺ ions. .

According to one embodiment, step (A) further comprises a heat treatment step a3) of the macroporous zeolite material obtained in step a2), the heat treatment comprising a drying step at a temperature of between 100 ° C. and 400 ° C.

According to one embodiment, in step (C), the precursor of the ceramic matrix is placed in the form of particles having a particle size such that more than 90% of the particles have a size of between 50 μηη and 600 μηη. According to one embodiment, the impregnation in step (B) is carried out with an aqueous or organic solution containing at least one soluble precursor compound of copper, nickel, cobalt, iron or manganese, preferably with a aqueous solution containing at least one precursor compound of the oxidation-reduction active mass chosen from the list consisting of the nitrates of the following formulas: Cu (N0 ₃ ) 2.xH ₂ 0, Ni (N0 ₃ ) ₂ .xH ₂ 0 , Co (NO ₃ ) ₂ .xH ₂ O, Fe (NO ₃ ) ₃ .xH ₂ O, Mn (NO ₃ ) ₂ · xH ₂ 0.

The impregnation in step (B) can be carried out in one or more successive stages, and preferably comprises intermediate stages of drying at a temperature of between 30 ° C. and 200 ° C. and / or calcination at a temperature of between between 200 ° C and 600 ° C when the impregnation is carried out in several successive stages. According to one embodiment of the invention, the drying in step (D) is carried out in air or in a controlled atmosphere, at a temperature between 30 ° C and 200 ° C, and preferably in air at a temperature between 100 ° C and 150 ° C.

According to one embodiment of the invention, the calcination in step (E) is carried out under air between 450 ° C. and 1400 ° C., preferably between 600 ° C. and 1000 ° C., more preferably between 700 ° C. and 900 ° C, and is carried out for a period of 1 to 24 hours, and preferably for a period of 5 to 15 hours.

According to one embodiment of the invention, in step a1) the zeolite crystals are mixed with at least one oxide selected from the list consisting of alumina, metal aluminates, silica, silicates, aluminosilicates, titanium dioxide, perovskites, zirconia, and / or a pore-forming agent intended to increase the macroporosity of the macroporous zeolite material.

According to a third aspect, the invention relates to a method of combustion of a hydrocarbon feedstock by oxido-reduction in a chemical loop using an oxygen carrier solid according to the invention or prepared according to the preparation method according to the invention.

Advantageously, the invention relates to a CLC process, preferably in which the oxygen carrier solid circulates between at least one reduction zone and an oxidation zone both operating in a fluidized bed, the temperature in the reduction zone. and in the oxidation zone being between 400 ° C and 1400 ° C, preferably between 600 ° C and 1100 ° C, and more preferably between 800 ° C and 1100 ° C.

Other objects and advantages of the invention will appear on reading the following description of examples of particular embodiments of the invention, given by way of non-limiting examples, the description being made with reference to the appended figures described herein. -after.

BRIEF DESCRIPTION OF THE FIGURES FIGS. 1A, 1B, 1C and 1D relate to an oxygen carrier solid according to Example 2 (example not in accordance with the invention). FIG. 1A is a diagram giving information on the porosity of the oxygen carrier solid. Fig. 1B is a diagram showing the conversion of methane as a function of oxidation-reduction cycles in a CLC process using the oxygen-carrying solid. Fig. 1C is a diagram showing the particle size distribution of the oxygen carrier solid before and after its use in a CLC process. Figure 1D is a scanning electron microscope (SEM) photograph of a polished section of a sample of the oxygen-carrying solid after its use in a CLC process.

FIGS. 2A, 2B, 2C and 2D relate to an oxygen carrier solid according to Example 3 (example not in accordance with the invention). Fig. 2A is a diagram giving information on the porosity of the oxygen carrier solid. Figure 2B is a diagram showing the conversion of methane versus oxidation-reduction cycles in a CLC process using the oxygen-carrying solid. FIG. 2C shows in (a) a SEM image and (b) an energy dispersive X-ray spectrometry (EDX) mapping of the oxygen-carrying solid prior to its use in a CLC process. Figure 2D is a SEM image of a polished section of a sample of the oxygen-carrying solid after its use in a CLC process.

FIGS. 3A, 3B, 3C, 3D and 3E relate to an oxygen carrier solid according to Example 4 (example according to the invention). FIG. 3A is a diffractogram obtained by X-ray diffractometry (XRD) of the oxygen carrier solid. Figure 3B shows in (a) a SEM backscattered electron micrograph and (b) an EDX mapping of a polished section of the oxygen carrier solid prior to its use in a CLC process. FIG. 3C is a diagram giving information on the porosity of the oxygen carrier solid. FIG. 3D represents in (a) a SEM backscattered electron micrograph and (b) an EDX mapping of a polished section of the oxygen carrier solid after its use in a CLC process. Figure 3E is a SEM image of a polished section of a sample of the oxygen-carrying solid after its use in a CLC process.

FIGS. 4A, 4B and 4C relate to an oxygen-carrying solid according to Example 5 (example not in accordance with the invention). FIG. 4A is a diagram giving information on the porosity of the oxygen carrier solid. Figure 4B shows a SEM picture of the oxygen-carrying solid prior to its use in a CLC process. FIG. 4C shows in (a) a SEM backscattered electron micrograph and (b) an EDX mapping of a polished section of the oxygen carrier solid after its use in a CLC process.

FIGS. 5A, 5B and 5C relate to an oxygen carrier solid according to Example 6 (example not in accordance with the invention). FIG. 5A is a diagram giving information on the porosity of the oxygen carrier solid. Figure 5B shows a polished section SEM of the oxygen-carrying solid prior to its use in a CLC process. Figure 5C shows a polished section SEM of the oxygen-carrying solid after its use in a CLC process. FIGS. 6A and 6B relate to an oxygen carrier solid according to Example 7 (example according to the invention). Fig. 6A is a diagram giving information on the porosity of the oxygen carrier solid. Figure 6B shows a polished section SEM of the oxygen carrier solid prior to use in a CLC process.

DESCRIPTION OF THE INVENTION The object of the invention is to propose an oxygen-carrying solid for a chemical-loop oxidation-reduction process, such as a CLC process, but also for other active mass chemical loop oxidation reduction methods such as a chemical loop reforming process (CLR with reference to the term "Chemical Looping Reforming") or a method of CLOU (with reference to the expression "Chemical Looping Oxygen Uncoupling "). The present invention also relates to the preparation and use of the oxygen-carrying solid in such processes.

The CLC processes generally use two separate reactors to perform on the one hand in a reduction reactor, the reduction of the active mass by means of a fuel, or more generally a gas, liquid or reducing solid. The effluents from the reduction reactor mainly contain CO ₂ and water, allowing easy capture of CO ₂ . On the other hand, in the oxidation reactor, the restoration of the active mass to its oxidized state by contact with air or any other oxidizing gas makes it possible to correlatively generate a hot energy vector effluent and a nitrogen stream. poor or free of nitrogen (where air is used). In the present description, reference is made in particular to the use of the oxygen carrier solid in a circulating fluidized bed CLC process, but the oxygen carrier solid according to the invention can also be used in any other type of process. chemical loop reduction (CLC, CLR, CLOU) in a fixed, mobile or bubbling bed, or in a rotating reactor. The solid carrier of oxygen

The oxygen carrier comprises: an oxidation-reduction active mass constituting between 5% and 75% by weight of the oxygen-carrying solid, preferably between 10% and 40% by weight, the oxidation-reduction active mass comprising a metal oxide or a mixture of metal oxides and being capable of exchanging oxygen under the redox conditions of said chemical loop-redox process; a ceramic matrix in which is dispersed the oxidation-reduction active mass, the ceramic matrix constituting between 25% and 95% by weight of the oxygen-carrying solid, preferably between 60% and 90% by weight, and the ceramic matrix comprising between 60% and 100% by weight, and preferably between 80% and 100% by weight, of at least one tectosilicate having a melting temperature above 1500 ° C, and preferably a melting temperature above 1700 ° C, and between 0% and 40% by weight of at least one oxide, of preferably between 0% and 20% by weight of at least one oxide. According to one embodiment, the ceramic matrix consists essentially of at least one tectosilicate having a melting point greater than 1500 ° C., and preferably a melting temperature greater than 1700 ° C. Essentially constituted is understood to comprise 100% of said tectosilicate, to 1%.

In addition to a ceramic matrix comprising at least one feldspar or feldsparoid having a melting point of greater than 1500 ° C., and preferably a melting point of greater than 1700 ° C., the oxygen-carrying solid according to the invention has a particular porosity. which, unexpectedly, makes it possible to limit the migration phenomenon of the active mass within the oxygen carrier particles. This initial texture significantly improves the lifetime of the particles in the chemical loop combustion process and is characterized in that: the total pore volume of the oxygen carrier solid Vtot, measured by mercury porosimetry, is between 0 , 05 and 0.9 ml / g; the total pore volume Vtot of the oxygen carrier solid comprises at least 10% of macropores. In other words, the pore volume of the macropores constitutes at least 10% of the total pore volume Vtot of the oxygen-carrying solid; the size distribution of the macropores within the oxygen carrier solid, measured by mercury porosimetry, is between 50 nm and 7 μηη.

It is recalled that according to the IUPAC nomenclature, we speak of micropores for pores whose size is less than 2 nm, mesopores for pores whose size is between 2 and 50 nm, and macropores for pores of size greater than 50 nm.

By initial texture is meant the texture prior to any use in a chemical loop-redox process such as CLC. The total pore volume of the solid is measured by mercury porosimetry, more precisely the measurement relates to the volume of mercury injected when the pressure exerted increases from 0.22 MPa to 413 MPa.

The total pore volume Vtot of the oxygen-carrying solid is preferably between 0.1 and 0.5 ml / g, and preferably between 0.1 and 0.4 ml / g.

Preferably, the total pore volume Vtot of the particles is constituted for at least 50% by macropores. In other words, the pore volume of the macropores constitutes at least 50% of the total pore volume Vtot of the oxygen-carrying solid. The remainder of the total pore volume may be indifferently constituted by microporosity or mesoporosity in any proportion whatsoever.

The size distribution of the macropores within the particles, measured by mercury porosimetry, is more preferably between 50 nm and 4 μηη, and even more preferably between 200 nm and 1 μηη.

The reason (s) why this initial macroporous texture of the oxygen-bearing solid minimizes the migration of the active mass within the particles is not yet explained. Without being bound to a particular theory, the inventors attribute this phenomenon, at least partially, to the fact that the diffusional limitations, usually reported for the mesoporous particles according to the prior art, are largely minimized because of the particularly open texture of the particles according to the invention. the invention. The gases can easily access the dispersed active mass within the ceramic matrix, limiting the mobility of the active mass due to concentration gradients, particularly during the oxidation of the particles. It is known that metal cations generally migrate through the primary oxide layer formed during the oxidation of a reduced metal particle (S. Mrowec, Z. Grzesik, "Oxidation of nickel and transport properties of nickel"). oxide, J.Phys.Chem.Solids, 64, 1651, 2004), since the diffusion rate of the metal cations in the oxide layer is higher than that of the oxygen anion (O ^{2 "} ). the nature of the ceramic matrix of the oxygen-carrying solid comprising tectosilicates with a high melting temperature (greater than 1500 ° C.), such as celsiane, would make it possible to minimize the phenomenon of densification of the particles sometimes observed in the prior art (see examples 5 and 6), which would limit the evolution of the porosity of the particles during the redox cycles. Ceramic l &mMice;

The ceramic matrix comprises at least one tectosilicate which is preferably a feldspar or a feldspathoid, and can be formed solely by such a tectosilicate.

Tectosilicates are silicates whose arrangement of [Si0 ₄ ] ^{4 "} tetrahedra is made up of a three-dimensional framework where each oxygen of the tops of the tetrahedra is shared with the neighboring tetrahedrons. [Si0 ₄ ] ^4" base tetrahedra that we find in all silicates are welded by their four vertices and each oxygen is bound to two cations. Can the chemical formula of other tectosilicates be derived from that of silica, generalized in O _? , where T indicates the tetrahedral cation, essentially silicon [Si0 ₄ ] ^{4 "} or aluminum [Al0 ₄ ] ^{5 ~} .The negative charge, which results from the replacement of silicon by aluminum in the tetrahedra, is compensated by the presence of M '^' (K \ Na ²⁺ , Ca ²⁺ , Sr ² ', Ba ²⁺ , etc.) cations in the cavities of the structure. This characteristic is common to feldspars, feldspathoids and zeolites, but the topology is different in all three cases. Feldspars are aluminous, calcic or alkaline tectosilicates (sodium or potassium).

Feldspathoids are tectosilicates with a high silica deficit.

The ceramic matrix comprises at least one feldspar selected from the list consisting of celsiana, slawsonite, anorthite, or feldspathoid, kalsilite. Preferably, the ceramic matrix consists essentially of at least one feldspar selected from the list consisting of the celsian, the slawsonite, ^anorthite.

Feldspars containing alkaline earth cations (Ca ^2+, Si ² * and Ba ^2+), such as celsian, the slawsonite, ^anorthite, have mechanical, thermal and electrical interesting. In particular, their coefficient of thermal expansion is very low, for example of 2.29 × 10 ^-6 K ^-1 for the monoclinic celsiane, which makes it possible to limit the mechanical stresses of deformation for use at high temperature, in particular in high temperature processes. oxidation reduction in a chemical loop such as CLC.

In addition, they have a high melting point, higher than 1500 ° C (1550 ° C, 100 ° C, and 1760 ° C, respectively for anorthite, slawsonite and celsiane), which is advantageous in the framework of oxidation-reduction processes in a chemical loop such that CLC where the temperature reached by the particles of the oxygen carrier is higher than that of the fluidizing gas, sometimes up to 120 ° C (Guo, XY; Sun, Y. L; Li, R; Yang, F. "Experimental investigations on temperature variation and inhomogeneity in a packed bed CLC reactor of large particles and low aspect ratio." Chem.Eng.Sci 107, 266, 2014.). The melting temperature of feldspars and feldspathoids strongly depends on the nature of the M ^{n +} cation, the Si / Al ratio and the arrangement of the tetrahedra in the crystallographic phase.

According to a preferred embodiment, the ceramic matrix comprises celsiane. Advantageously, the ceramic matrix consists essentially of celsiane. Celsiane is a feldspar which advantageously has a high mechanical strength and a very low coefficient of thermal expansion. It also has a high melting point (1760 ° C).

Table 1 below lists the feldspars and feldspathoids mentioned that can make up the ceramic matrix, as well as examples of other feldspathoids whose melting point is below 1500 ° C.

Table 1

The ceramic matrix of the solid carrier of ^oxygen according to ^the invention may also consist of a mixture of one or more tectosilicates and other oxides typically used as supports for catalysts in petroleum refining processes. Thus the ceramic matrix may comprise at least one oxide chosen from the list constituted by alumina, metal aluminates, silica, silicates, aluminum silicates, aluminosilicates, titanium dioxide, perovskites, zirconia.

In the present description the term oxide covers a mixed oxide, that is to say a solid resulting from the combination of oxide ions O ^{2 "} with at least two cationic elements (for example calcium aluminate CaAl ₂ 0 ₄ or magnesium aluminate MgAl ₂ 0 ₄ ) By mixing oxides is meant at least two distinct solid compounds each being an oxide.

According to the invention, the ceramic matrix is obtained from a precursor based on zeolite. Zeolites are crystallized microporous solids of the family of aluminosilicates that can be found frequently in nature. These materials can also be synthesized, such as frequently for use as adsorbents or catalysts in the chemical industry. Zeolites have three-dimensional structures formed by the arrangement of [Si0 ₄ ] ^{4 ~} and [Al0 ₄ ] ^{5 ~} tetrahedra bonded by bridging oxygen atoms. The electroneutrality of the assembly is ensured by the presence of one or more exchangeable compensation cations. The general formula of a zeolite is M _{x / m} Al _x S ₉ 2-x 0 ₃ e ₄ , y H ₂ 0 with M ^{m +} the extra-network charge cation + m.

It is known that celsiane can be obtained from a zeolite exchanged with barium. In the case of zeolite A, X and LSX exchanged with barium, a high temperature treatment, that is to say higher than 1000 ° C, causes the formation of celsiane, according to the following sequence: zeolite → amorphous phase → hexagonal celsiane → monoclinic celsiane. The formation of monoclinic celsiane from pure BaX ("BaX" for zeolite X exchanged with barium) requires a heat treatment of 24 ° to 1550 ° C. (S. Esposito et al., A comparative study of the thermal transformations of Ba-exchanged zeolites A, X and LSX, J. Eur Ceram Soc., 24, 2004, 2689). After a heat treatment of 28h at 1100 ° C, the hexagonal celsiane is still predominantly present, but a beginning of crystallization of monoclinic celsiane is observed. In addition to the nature of the zeolite structure, the presence of various alkaline cations (eg Na ⁺ , Li ⁺ , K ⁺ ) influences the temperatures at which these different phase transitions take place. According to Esposito et al. 2004, these differences in behavior are related to the different degrees of compositional homogeneity of the mixture in the amorphous phases obtained during the heat treatment of the microporous structure of zeolites. The oxygen carrier solid according to the invention is prepared from various zeolites of low Si / Al ratio, impregnated with a precursor of an oxidation-reduction active mass, typically a metal nitrate, which decompose by calcination, preferably in air and at a temperature of between 450 ° C. and 1400 ° C., to form the oxidation-reduction active mass (eg a metal nitrate oxide) dispersed in a ceramic matrix composed of tectosilicates or mixtures of tectosilicates, depending on the nature of the cation or cation mixture in the zeolite cages and the Si / Al ratio of the zeolite. The melting temperature of the ceramic matrix depends on the nature of the cation M ^{m +} , the Si / Al ratio and the arrangement of the tetrahedra in the crystallographic phase. The preparation of the oxygen carrier solid according to the invention is detailed later in the description.

La masse atewe dgxydg ^

The oxygen-carrying solid according to the invention comprises an oxidation-reduction active mass which comprises, and preferably consists of, at least one metal oxide included in the list consisting of Fe, Cu, Ni and Mn oxides. and Co, a perovskite having redox properties, preferably a perovskite of formula CaMnO ₃ , a metal aluminate spinel having redox properties, preferably a metal aluminate spinel of formula CuAl ₂ O ₄ or of formula CuFe ₂ ₄ . The spinel of formula CuFe ₂ O ₄ is a cuprospinelle. Preferably, the oxidation-reduction active mass comprises at least one copper oxide, for example of formula CuO, and is more preferably constituted by at least one copper oxide, for example of formula CuO.

According to the invention, the oxygen-carrying solid advantageously has a dispersed active mass within the ceramic matrix, typically an initial distribution of the relatively homogeneous active mass, and the migration of the active mass within the particles of the solid carrier. Oxygen is minimized during the redox cycles of the chemical-loop oxidation-reduction process as exemplified by some examples later in the description.

The oxido-reducing active mass is capable of exchanging oxygen under the redox conditions of the chemical loop redox process. The active mass is reduced according to the reaction (1) already described above, during a contact reduction step a hydrocarbon feedstock, and is oxidized according to the reaction (2) or (3) already described above, during an oxidation step in contact with an oxidizing gas.

The oxygen storage capacity of the oxido-reducing active mass is advantageously, depending on the type of material, between 1% and 15% by weight. Advantageously, the amount of oxygen effectively transferred by the metal oxide is between 1 and 3% by weight, which makes it possible to use only a fraction of the oxygen transfer capacity.

FQime du_ sojide_gort ^

The oxygen carrier solid according to the invention is preferably in the form of particles, which can be fluidized in the oxidation-reduction process in a chemical loop, in particular be implemented in a circulating fluidized bed. They may be fluidizable particles (fluidizable powder, generally called "fluidisable carrier" in English) belonging to groups A, B or C of the Geldart classification (D. Geldart, "Types of gas fluidization", Powder Technol. (5), 285-292, 1973), and preferably the particles belong to group A or group B of the Geldart classification, and preferably to group B of the Geldart classification.

Preferably, the particles of the oxygen-carrying solid have a particle size such that more than 90% of the particles have a size of between 50 μηη and 600 μηη, more preferably a particle size such that more than 90% of the particles have a size of between 80 μηη and 400 μηη, more preferably a particle size such that more than 90% of the particles have a size of between 100 μηη and 300 μηη, and even more preferably a particle size such that more than 95% of the particles have a size between 100 μηη and 300 μηη.

Preferably, the particles of the oxygen-carrying solid have a grain density of between 500 kg / m ³ and 5000 kg / m ³ , preferably a grain density of between 800 kg / m ³ and 4000 kg / m ³ , and even more preferably a grain density of between 1000 kg / m ³ and 3000 kg / m ³ .

The particles of the oxygen-bearing solid are preferably substantially spherical.

Size distribution and morphology of particles for use in another type of chemical loop process (CLC, CLR, CLOU) in fixed bed, moving bed or rotating reactor are adapted to the envisaged process. For example, in the case of a use of the oxygen carrier solid in a process using a fixed bed or rotating reactor technology, the preferred size of the particles is greater than 400 μηη, in order to minimize the pressure losses. in the reactor (s), and the morphology of the particles is not necessarily spherical. The morphology is dependent on the shaping mode, for example in the form of extrudates, beads, monoliths or particles of any geometry obtained by grinding larger particles. In the case of a shaping of monolithic type, the solid carrier of oxygen, in the form of particles, is deposited on the surface of the ceramic monolith channels by the coating methods known to those skilled in the art. or the monolith itself consists of the particles according to the invention.

Particle size can be measured by laser particle size.

The size distribution of the particles is preferably measured using a laser granulometer, for example Malvern Mastersizer 3000, preferably in a liquid path, and using the Fraunhofer theory.

Preparation of the oxygen carrier solid

The oxygen carrier solid is prepared according to a process comprising the following steps: Step (A): Preparation of a Precursor of a Ceramic Matrix Step (A) comprises: - a1) the preparation of a macroporous zeolite material said material comprising zeolite crystals with a mean diameter of less than or equal to 3 μηη, and preferably a number-average diameter of between 0.4 μηη and 2 μηη, and even more preferably a number-average diameter of between 0 , 5 μηη and 1, 7 μηη; and - a2) a cationic exchange of said macroporous zeolite material with a solution of precursor ions, the precursor ions being chosen to form a tectosilicate with a melting point> 1500 ° C. of the ceramic matrix at the end of step (D ), said cation exchange being followed by a washing of said macroporous zeolite material to obtain said precursor of the ceramic matrix. Step al}

Preferably, step a1) for preparing a macroporous zeolite material comprises the following steps:

- a'1) agglomeration of zeolite crystals with a clay binder to form a zeolite agglomerate;

- a'2) the shaping of the zeolite agglomerate obtained in step a'1) to produce particles, followed by drying of said particles, and possibly followed by a sieving and / or cycloning step ;

- a'3) calcination of the zeolite agglomerate particles obtained in step a'2) at a temperature between 500 ° C and 600 ° C to produce the macroporous zeolite material in particulate form. The particles produced have sufficient mechanical strength for their subsequent use;

The clay binder is an agglomeration binder intended to ensure the cohesion of the crystals in the form of particles. This binder can also contribute to imparting mechanical resistance to the particles so that they can withstand the mechanical stresses to which they are subjected during their implementation within the chemical loop redox units.

The proportions of agglomeration binder and zeolite employed can be typically from 5 parts to 20 parts by weight of binder per 95 parts to 80 parts by weight of zeolite.

In step a1), in addition to the zeolite crystals and the clay binder, the zeolite crystals may be mixed with at least one oxide selected from the list consisting of alumina, metal aluminates, silica, silicates, aluminum silicates, aluminosilicates, titanium dioxide, perovskites, zirconia. Thus, it will be obtained at the end of the process an oxygen carrier solid having a non-zero and less than 40%, of preferably less than 20%, oxide in the ceramic matrix other than the tectosilicates or melting temperature greater than 1500 ° C.

Alternatively, such an oxide may be formed, in the desired quantities, at the end of the treatments of the zeolite agglomerate and the precursor of the ceramic matrix, without adding said oxide to the zeolite crystals during step (A). ).

In step a1), it is also possible to mix the zeolite crystals with a pore-forming agent intended to increase the macroporosity of the macroporous zeolite material.

In step a1), it is also possible to mix the zeolite crystals with at least one of the abovementioned oxides and with a pore-forming agent. In step a1), other additives may also be used, intended to facilitate the agglomeration and / or to improve the hardening and / or increase the macroporosity of the agglomerates formed.

Advantageously, the zeolitic crystals comprise at least one zeolite with an Si / Al molar ratio of between 1.00 and 1.5, and preferably at least one zeolite chosen from zeolites A, X, LSX and low-silica EMT. Zeolites A are of structural type LTA, and of ratio Si / Al = 1. X zeolites are of structural type FAU and Si / Al ratio of between 1 and 1.5, as is the case for the LSX zeolite (Low Silica X). The low-silica EMT zeolites are of structural type EMT and Si / Al ratio of between 1.0 and 1.4 (Mintova et al., Chem Mater 24, 4758-4765, 2012, and Science, Jan. 2012, 335, 70-73). Those skilled in the art can refer to the "Atlas of zeolite framework types", 6th revised Edition, 2007, Ch.Baerlocher, WMMeier, DH Oison to obtain the characteristics of these types of zeolites. It may therefore be crystals formed by only one of the zeolites mentioned, or by a mixture of said zeolites, and preferably by only one of the zeolites mentioned, in particular zeolite X or LSX. The zeolite crystals A, X, LSX and low-silica EMT can be derived from synthesis and the compensating cations are mainly, or even exclusively, sodium cations (for example NaX (or 13X), NaA (or 4A) crystals), but it is not beyond the scope of the invention using crystals having undergone one or more cationic exchanges, between the synthesis in sodium form and their implementation in step a1). The estimation of the number average diameter of the zeolite X crystals used in step a1) and the zeolite X crystals contained in the agglomerates is preferably carried out by observation under a scanning electron microscope (SEM) or by observation under an electron microscope in transmission (MET). In order to estimate the size of the zeolite crystals on the samples, a set of images is carried out at a magnification of at least 5000. The diameter of at least 200 crystals is then measured using dedicated software. for example the Smile View software from the LoGraMi editor. The accuracy is of the order of 3%.

The optional step a'4) of zeolitization of the clay binder makes it possible to convert all or part of the binder into zeolite, preferably into zeolite with an Si / Al molar ratio of between 1.00 and 1.5, and preferably zeolite A , X, LSX or low-silica EMT, in order to obtain a macroporous zeolite material consisting essentially of zeolite, the non-zeolite phase being typically in an amount of less than 5%, and corresponding to non-zeolite residual binder or any other amorphous phase after zeolitization, while maintaining or even improving the mechanical strength of the macroporous zeolite material, as taught by patents FR 2 903 978 and FR 2 925 366.

The clay agglomeration binder used in step a '1) comprises, and preferably consists of, a clay or a mixture of clays, to which a source of silica may be added. These clays are preferably chosen from kaolins, kaolinites, nacrites, dickites, halloysites, attapulgites, sepiolites, montmorillonites, bentonites, illites and metakaolins, as well as mixtures of two or more of them in all proportions. In the case of the optional zeolitization step a'4), the clay agglomeration binder used in step a'1) contains at least 80%, preferably at least 90%, more preferably at least 95% more particularly at least 96% by weight of zeolitizable clay and may also contain other minerals such as bentonite, attapulgite, and the like. By zeolitic clay is meant a clay or a mixture of clays which are capable of being converted into zeolite material, most often by the action of an alkaline basic solution. Zeolizable clay generally belongs to the family of kaolin, kaolinite, nacrite, dickite, halloysite and / or metakaolin. Kaolin is preferred and most commonly used. After drying in step a'2), the calcination in step a'3) is carried out at a temperature in general of between 500 ° C. and 600 ° C., for example at 550 ° C., and makes it possible to transform zeolitic clay, typically kaolin, in meta-kaolin which can after being converted to zeolite during the optional zeolitization step (step a'4)). The principle is exposed in "Zeolite Molecular Sieves" by DW Breck, John Wiley and Sons, New York, (1973), p. 314-315. The zeolitization of the agglomeration binder is carried out according to any method now well known to those skilled in the art and may for example be carried out by immersion of the product of step a'3) in an alkaline basic solution, generally aqueous, by an aqueous solution of sodium hydroxide and / or potassium hydroxide.

At the end of step a1) the macroporous zeolite material contains alkaline or alkaline earth cations, and more generally sodium and / or potassium cations.

The macroporous zeolite material at the end of step a1) can also be obtained, alternatively with the succession of steps a'1) to a'4) described above, by any alternative method leading to zeolite particles, and in particular by the method described in US Pat. No. 4,818,508 starting from agglomerates of zeolitic clay subjected to zeolitization by the action of an alkaline basic solution.

Floor a2}

The cationic exchange (step a2) can be carried out with a solution comprising alkaline ions, preferably K ⁺ , or alkaline earth ions, and preferably with a solution comprising alkaline earth ions.

The cationic exchange is more preferably carried out with a solution comprising ions selected from Ba ²⁺ , Sr ²⁺ , Ca ²⁺ ions, and even more preferably with a solution comprising Ba ²⁺ ions. Preferably, the solution used is an aqueous solution in which a salt is dissolved, preferably a barium salt such as barium chloride BaCl ₂ , a strontium salt such as strontium chloride SrCl ₂ or a calcium salt such as chloride calcium CaCl ₂ , and preferably BaCl ₂ barium salt.

Step a2) of cationic exchange of the zeolite is carried out by contacting the macroporous zeolite material resulting from step a1), in particular the macroporous zeolite material in the form of particles resulting from step a'3) or a'4), with an alkali or alkaline earth metal salt, such as BaCl ₂ , in aqueous solution, preferably at a temperature between room temperature and 100 ° C, and preferably at a temperature between 80 ° C and 100 ° C. To quickly obtain an exchange rate in cation, eg barium, high, ie greater than 90%, it is preferred to operate with a large excess of the cation exchange with respect to the cations of the zeolite that is to be exchanged.

The chemical analysis of the precursor of the ceramic matrix resulting from step a2) or zeolite crystals used in step a1) is carried out according to conventional techniques, in particular by X-ray fluorescence as described in standard NF EN ISO 12677: 201 1 on a wavelength dispersive spectrometer (WDXRF), for example Tiger S8 from Bruker, or by inductively coupled plasma atomic emission spectrometry (ICP-OES for Inductively Coupled Plasma-Optical Spectroscopy emission according to the English terminology) according to the UOP 961-12 standard. The cationic exchange of zeolites can be done without destroying the zeolite structure. On the other hand, it is known that a total destruction of the zeolite structure can be obtained if it is sought to dehydrate the zeolite exchanged, as for example in the case of zeolite A thus exchanged with barium (Howard S. Sherry, Harold F. Walton, "The Exchange-Traded Properties of Zeolites." IIon Exchange, Synthetic Zeolite Linde 4-AJ Phys Chem, 71, 5, 1457, 1967). Thus, the precursor of the ceramic matrix obtained at the end of the optional thermal treatment step a3) can be totally or partially amorphous, in particular in the case where the zeolite A is used in step a1), or when the temperature of the heat treatment of step a3) is too high to maintain the zeolite structure. Step a3J_

The preparation of the precursor of the ceramic matrix during step (A) may further comprise an additional step a3) of heat treatment of the macroporous zeolite material obtained in step a2). This heat treatment comprises a drying step at a temperature of between 100 ° C. and 400 ° C. Step (B): impregnation of the precursor of the ceramic matrix

The precursor of the ceramic matrix obtained in step (A) is impregnated with a precursor compound of an oxidation-reduction active mass.

The impregnation may be carried out with an aqueous or organic solution containing at least one soluble precursor compound of copper, nickel, cobalt, iron or manganese. Preferably, the impregnation is carried out with an aqueous solution containing at least one precursor compound of the oxidation-reduction active mass chosen from the list consisting of the nitrates of the following formulas: Cu (N0 ₃ ) 2.xH ₂ 0, Ni (N0 ₃ ) ₂ .xH ₂ O, Co (NO ₃ ) 2.xH ₂ O, Fe (NO ₃ ) ₃ .xH ₂ O, Mn (NO ₃ ) ₂ .xH ₂ 0. Advantageously, the copper nitrate of Copper Cu (N0 ₃ ) ₂ .xH ₂ 0 is chosen to carry out this impregnation, in order to obtain an oxido-reducing active mass of copper oxide (s), for example a copper oxide of formula CuO, to form the solid carrier of oxygen.

The amount of precursor of the oxidation-reduction active mass used for the impregnation stage is chosen so that the active redox mass constitutes between 5% and 75% by weight of the solid carrier substance. oxygen.

The impregnation can be carried out in one or more successive stages.

If the impregnation is carried out in several successive stages, intermediate stages of drying at a temperature of between 30 ° C. and 200 ° C. and / or calcination at a temperature of between 200 ° C. and 600 ° C. are preferably carried out. Step (C): shaping of the precursor of the ceramic matrix

The precursor of the ceramic matrix is formed into particles during step (a1) or after step (B).

The shaping in step a1) has been described above. This is the shaping in step a'2) of the zeolite agglomerate obtained in step a'1). During this step a'2) the shaping is followed by a drying of the particles, which is optionally followed by a sieving and / or cycloning step.

During this step (C), the precursor of the ceramic matrix is shaped so as to obtain particles having a particle size such that more than 90% of the particles have a size of between 100 μηη and 500 μηη. If a circulating fluidized bed implementation is envisaged for the chemical loop oxidation-reduction process using the oxygen-carrying solid, it will be preferred to perform a shaping so as to obtain a size distribution of the particles of the zeolite agglomerate, or precursor of the ceramic matrix from step (B), such that said particles belong to class A or class B of the Geldart classification. In a preferred manner, the shaping is carried out so as to produce particles having the following particle size: more than 90% of the particles have a size of between 100 μηη and 500 μηη, and a grain density of between 500 kg / m ³ and 5000 kg / m ³ . Very preferably, the shaping is carried out so as to produce particles of the following particle size: more than 90% of the particles have a size of between 100 μηη and 300 μηη, and a grain density of between 800 kg / m ³ and 4000 kg / m ³ . Even more preferably, the shaping is carried out so as to produce particles having the following particle size: more than 95% of the particles have a size of between 100 μηη and 300 μηη, and a grain density of between 1000 kg / m ³ and 3000 kg / m ³ . The shaping, which can directly follow the agglomeration stage a '1), can be carried out by any techniques known to those skilled in the art, such as extrusion, compaction, agglomeration on a granulating plate. , granulator drum, wet or dry granulation, etc., and preferably by granulation or any other technique making it possible to obtain particles of spherical shape. The shaping may optionally comprise a sieving and / or cycloning step, in order to obtain agglomerates of the desired particle size.

Step (D): Drying of the precursor of the ceramic matrix

The precursor of the impregnated ceramic matrix in the form of particles obtained at the end of all of the steps (A), (B) and (C) is subjected to a drying step. This drying is preferably carried out in air or in a controlled atmosphere (controlled relative humidity, under nitrogen), at a temperature of between 30 ° C. and 200 ° C. For controlled atmosphere is meant for example with a controlled relative humidity or under nitrogen.

More preferably, the drying is carried out in air at a temperature of between 100 ° C. and 150 ° C.

Step (E): calcination of the precursor of the ceramic matrix

The precursor of the impregnated and dried ceramic matrix obtained in step (D) is calcined to obtain the particulate oxygen carrier solid. This calcination is preferably carried out in air between 450 ° C. and 1400 ° C., more preferably between 600 ° C. and 1000 ° C., and even more preferably between 700 ° C. and 900 ° C.

This calcination can be carried out for a period of 1 to 24 hours, and preferably for a period of 5 to 15 hours.

Advantageously, a ramp for increasing the temperature between 1 ° C./min and 50 ° C./min, and preferably between 5 ° C./min and 20 ° C./min, is applied to reach the given calcination temperature. The time to implement this temperature ramp is not included in the calcination time ranges indicated above.

The calcination enables the formation of the tectosilicate (s) of the solid ceramic matrix carrying oxygen in the form of particles, a matrix in which the redox active mass is dispersed.

It also appears that the calcination step (E) has a limited impact on the initial macroporous structure of the particles, and all the more limited when the calcination is carried out at a temperature between 700 ° C and 900 ° C. A small increase in macropore diameter and a small decrease in total pore volume can be observed.

According to a preferred embodiment, the preparation of an oxygen carrier of formula CuO / BaAl ₂ Si ₂ O ₈ according to the invention is carried out according to the following steps: Firstly, step (A) of preparation of a precursor of a ceramic matrix of celsiana in the form of particles.

The precursor of the ceramic matrix BaAl ₂ Si ₂ O ₈ is a macroporous zeolite agglomerate consisting essentially of zeolite with a low Si / Al atomic ratio, that is to say with an Si / Al ratio of less than 1.5 (and greater than 1). The zeolitic crystals may comprise a zeolite chosen from zeolites A, X, LSX and low-silica EMT, alone or as a mixture. The zeolites of the agglomerate are exchanged with barium. The precursor of the BaAl ₂ Si ₂ O ₈ ceramic matrix is prepared according to the following steps: a1) the preparation of a macroporous zeolite material comprising an agglomeration of zeolite crystals with an Si / Al atomic ratio of between 1.00 and 1, 50, by example of zeolite A, X, LSX, low-silica EMT, alone or as a mixture, with a mean diameter less than or equal to 3 μηη, preferably between 0.4 μηη and 2 μηη, and preferably between 0 , 5 μηη and 1, 7 μηη, with a binder based on a clay or a mixture of clays (step a'1), and a shaping to form particles, then a drying of the particles (step a'2), followed by calcination

(step a'3). A possible zeolitization of the clay binder by the action of an alkaline basic solution can be carried out (step a'4). Alternatively, the shaping in the form of particles is carried out subsequently, after the impregnation step (B); a2) the cationic exchange of the particles of the macroporous zeolite material resulting from step a1) by contacting with a solution of barium ions, followed by washing of the product thus treated. The barium exchange of the cations of the zeolite is carried out by contacting the macroporous zeolite material from step a1), in particular the macroporous zeolite material in particulate form resulting from step a'3) or 4), with a barium salt, such as BaCl ₂ , in aqueous solution at a temperature between room temperature and 100 ° C, and preferably between 80 ° C and 100 ° C. To rapidly obtain a high barium exchange rate, ie greater than 90%, it is preferred to operate with a large excess of barium with respect to the cations of the zeolite that is to be exchanged, typically such as the BaO / Al ₂ ratio. 0 ₃ is of the order of 10 to 12 by proceeding by successive exchanges. The degree of exchange by the barium ions is determined by the ratio between the number of moles of barium oxide, BaO, and the number of moles of all the oxides of alkaline and alkaline-earth ions (typically the number of moles of BaO + K ₂ O + Na ₂ O). The barium exchange of zeolites X, LSX, or A or low-silica EMT, is done without destruction of the zeolite structure. a3) the optional heat treatment of the exchanged macroporous zeolite material from step a2), comprising a drying step at a temperature of between 100 ° C and 400 ° C. The precursor of the ceramic matrix obtained at the end of this step a3) may be totally or partially amorphous, especially in the case where zeolite A is used in step a1).

The conditions and details on the products and materials implemented in the sub-steps of step (A) are not repeated here and correspond to those described more generally above. Then, step (B) is carried out for impregnating the precursor of the ceramic celsiane matrix: the precursor of the ceramic matrix, preferably shaped according to step (C) already described, is impregnated with an aqueous solution or organic containing at least one soluble precursor of copper, nickel, cobalt, iron and / or manganese, as described in detail above.

Then the drying step (D) of the precursor of the ceramic matrix of celsiana impregnated in the form of particles is carried out. This drying step is in accordance with what has been described generally above.

Finally, the calcination step (E), as already described, is carried out with particles from step (D), in order to form the oxygen carrier comprising a celsiana matrix BaAl ₂ Si ₂ 0 ₈ within from which is dispersed the active mass of CuO oxidation reduction, and having the specific porous texture described above. It appears that the impregnation of zeolite shaped and exchanged by barium, by one or more metal precursors of the active redox active mass, such as precursors of Cu, Ni, Co, Fe and / or Mg does not modify the transformation sequence of the zeolite structure mentioned by Esposito et al. 2004, but phase transition temperatures are lowered. In fact, a mixture of hexagonal and monoclinic celsiane with tenorite (CuO) is obtained after calcination for 12 hours at 800 ° C. of the Cu (Cu ₃ ) 2 impregnated BaX zeolite precursor, while a calcination of 6 hours at 1100 ° C. It is necessary to obtain the hexagonal celsiane from the zeolite precursor BaX not impregnated with copper nitrate, and 24h at 1550 ° C. to obtain the monoclinic celsiane.

Use of the oxygen carrier

The oxygen-carrying solid is intended to be used in a chemical loop-redox process. The invention thus relates to a chemical loop redox process using the oxygen carrier solid as described, or prepared according to the method of preparation as described.

Advantageously, the oxygen-bearing solid described is used in a CLC process of a hydrocarbon feedstock, in which the oxygen-carrying solid is in the form of particles and circulates between at least one reduction zone and an oxidation zone all operating both in a fluidized bed. The temperature in the reduction zone and in the oxidation zone is between 400 ° C. and 1400 ° C., and preferably between 600 ° C. and 1100 ° C., and even more preferentially between 800 ° C. and 1100 ° C. ° C.

The hydrocarbon feedstock treated can be a solid, liquid or gaseous hydrocarbon feedstock: gaseous fuels (eg natural gas, syngas, biogas), liquids (eg fuel oil, bitumen, diesel, gasoline, etc.), or solids (ex. : coal, coke, pet-coke, biomass, oil sands, etc.).

The operating principle of the CLC process in which the oxygen-bearing solid described is used is as follows: a reduced oxygen-carrying solid is brought into contact with an air flow, or any other oxidizing gas, in a zone reaction called air reactor (or oxidation reactor). This results in a depleted airflow and a particle stream of the reoxidized oxygen carrier. The stream of oxidized oxygen carrier particles is transferred to a reduction zone called a fuel reactor (or reduction reactor). The flow of particles is brought into contact with a fuel, typically a hydrocarbon feedstock. This results in a combustion effluent and a stream of reduced oxygen carrier particles. The CLC installation may include various equipment for heat exchange, pressurization, separation or possible recirculation of material around the air and fuel reactors.

In the reduction zone, the hydrocarbon feedstock is brought into contact, for example cocurrently, with the particulate oxygen-carrying solid comprising the oxido-reducing active mass in order to carry out the combustion of said feedstock by reducing the oxido-reducing active mass. The redox active mass M _x O _y, M representing a metal, is reduced to the state M _x O _y 2n-m / 2, through the hydrocarbon feedstock C _n H _m which is correlatively oxidized in C0 ₂ and H ₂ 0, according to the reaction (1) already described, or optionally in mixture CO + H ₂ according to the proportions used and the nature of the metal M. The combustion of the charge in contact with the active mass is carried out at a temperature generally between 400 ° C. and 1400 ° C., preferably between 600 ° C. and 1100 ° C., and even more preferably between 800 ° C. and 1100 ° C. The contact time varies depending on the type of fuel load used. It typically varies between 1 second and 10 minutes, for example preferably between 1 and 5 minutes for a solid or liquid charge, and for example preferably from 1 to 20 seconds for a gaseous charge. A mixture comprising the gases from the combustion and the particles of the oxygen-carrying solid is removed, typically at the top of the reduction zone. Gas / solid separation means, such as a cyclone, make it possible to separate the combustion gases from the solid particles of the oxygen carrier in their most reduced state. These are sent to the oxidation zone to be re-oxidized, at a temperature generally between 400 ° C. and 1400 ° C., preferably between 600 and 1100 ° C., and even more preferably between 800 ° C. and 1100 ° C.

In the oxidation reactor, the active mass is restored to its oxidized state M _x O _y in contact with the air, according to reaction (2) already described (or according to reaction (3) if the oxidizing gas is H ₂ 0), before returning to the reduction zone, and after being separated from the depleted oxygen air evacuated at the top of the oxidation zone 100.

The active mass, passing alternately from its oxidized form to its reduced form and vice versa, describes an oxidation-reduction cycle.

The disclosed oxygen carrier solid may also be used in another chemical loop redox process such as a CLR process or a CLOU process.

The technology used in the chemical loop oxidation reduction process is preferably that of the circulating fluidized bed, but is not limited to this technology, and can be extended to other technologies such as fixed bed, mobile or bubbling bed , or rotating reactor. Examples

The interest of the solid oxygen carriers according to the invention in the chemical loop processes, in particular CLC, in particular the minimization of the migration of the active mass within the particles during the redox cycles, is exposed through the examples 1 to 7 below. Examples 2, 3, 5 and 6 relate to oxygen-carrying solids not in accordance with the invention. Examples 4 and 7 relate to oxygen-carrying solids in accordance with the invention. Example 1: Aging test for oxygen-carrying solids in a batch fluidized bed

The aging of the oxygen carrier solids in a batch fluidized bed was carried out in a unit consisting of a quartz reactor, an automated system for supplying the gas reactor and a system for analyzing the gases leaving the reactor. reactor. This aging test approximates the conditions of use of the oxygen-carrying solid in a chemically-looped oxidation-reduction process, in particular of a chemical-reduction oxidation-reduction loop.

The distribution of gases (CH ₄ , CO ₂ , N ₂ , air) is ensured by mass flow meters. For safety reasons, a nitrogen sweep is carried out after each period of reduction and oxidation.

The height of the quartz reactor is 30 cm, with a diameter of 4 cm in its lower part (on 24 cm high), and 7 cm in its upper part. A quartz sinter is placed at the bottom of the reactor to ensure the distribution of the gases and a good fluidization of the particles. Another sinter is placed in the upper part of the reactor to prevent the loss of fines during the test. The reactor is heated using an electric oven. Part of the gas leaving the reactor is pumped to the gas analyzers, cooled to condense most of the water formed during the reduction and then dried with calcium chloride. The gas concentrations are measured using non-dispersive infrared analyzers for CO, CO ₂ and CH ₄ , a paramagnetic analyzer for oxygen, and a TCD detector for hydrogen.

Standard test conditions: 100 grams of particles are introduced into the quartz reactor and then heated to 900 ° C under air flow (60 Nl / h). When the temperature of the bed is stabilized at 900 ° C. in air, 250 cycles are carried out according to the following steps:

1 - Scanning with nitrogen (60 Nl / h) 2- Injection of a CH ₄ / CO ₂ mixture (30 N / h / 30 Nl / h) (reduction of the particles)

3- Nitrogen scavenging (60 Nl / h)

4- Air injection (60 Nl / h) (oxidation of particles) The conversion of the oxygen-carrying solid (amount of oxygen supplied by the oxygen-carrying solid to carry out the methane conversion, expressed in% by weight of the oxidized oxygen carrier) is calculated from the gas conversion data, and the reduction time (step 2 of the cycle) is adjusted after the first cycle so that the oxygen carrier solid releases about 2% oxygen by weight (relative to the oxidized mass of oxygen-carrying solid introduced) at each reduction cycle. The oxidation time (step 4 of the cycle) is sufficient to completely reoxidize the particles (15 min).

Particle size distribution was measured using a Malvern particle size analyzer, using Fraunhofer's theory. The granulometer is a Malvern Mastersizer 3000 particle size analyzer, and the measurement is carried out in a liquid way.

The mercury porosimetry measurements were performed on the Autopore IV device marketed by Micromeritics, considering a mercury surface tension of 485 dyn / cm and a contact angle of 140 °. The minimum pore size measurable by mercury porosimetry is 3.65 nm. The nitrogen adsorption isotherms were carried out on the ASAP 2420 device marketed by Micromeritics.

Example 2: CuO / Alumina Oxygen Carrier Solid

According to this example 2, an oxygen-carrying solid is formed from alumina as a support matrix for an active oxide-reduction mass of copper oxide (s). The alumina used for this example is Puralox SCCa 150-200 marketed by Sasol. The particle size distribution of the aluminum support indicates Dv10 = 104 μηη, Dv50 = 161 μηι and Dv90 = 247 μπι.

The pore volume of the particles measured by mercury porosimetry is 0.450 ml / g, and the pore size distribution is between 5 and 15 nm, centered on 9 nm. The macroporous volume of the support measured by mercury porosimetry is 0.007 ml / g (1.5% of the total pore volume).

The nitrogen adsorption isotherm of Puralox makes it possible to measure a specific surface area of 199 m ² / g, a microporous volume (pores <2 nm) of zero and a mesoporous volume (2 nm <pores <50 nm) of 0.496. ml / g. 233 g of Puralox alumina was impregnated according to the dry impregnation method, with 96.5 g of copper nitrate trihydrate dissolved in the necessary volume of demineralized water. After drying at 120 ° C. and calcination at 850 ° C. for 12 hours, a solid containing 12% by weight of CuO is obtained; the crystallographic phases detected by XRD are γ-ΑΙ203 and CuO. The distribution of copper within the particles is homogeneous.

The pore volume of the particles of the solid obtained, measured by mercury porosimetry, is 0.367 ml / g, of which 0.015 ml / g (ie 4% of the total pore volume measured by mercury porosimetry) is due to the macroporosity. The pore size distribution is between 5 and 20 nm and centered on 11.25 nm, as can be seen in the diagram of FIG. 1A showing the volume of mercury injected Vi (ml / g) in the porosity, as well as that the ratio dV / dD (derived from (introduced Hg volume / pore size), giving information of the pore size distribution), as a function of the pore diameter (nm), for the oxygen carrier solid according to this example. The particles are therefore essentially mesoporous. The nitrogen adsorption isotherm of the oxygen-carrying solid according to this example makes it possible to measure a surface area of 135 m ² / g, a microporous volume (pore size <2 nm) and a mesoporous volume (2 nm <pores <50 nm) of 0.404 ml / g.

The oxygen-carrying solid according to this example was aged under the conditions described in Example 1. FIG. 1B is a diagram showing the normalized conversion rate Xc of methane as a function of the number N of oxidation-reduction rings in a CLC process using the oxygen carrier solid according to Example 2.

The conversion of methane is of the order of 98% at the beginning of the test, it increases until reaching 100%, then a progressive deactivation is observed after the hundredth cycle. The conversion then stabilizes around 95%.

It should be noted that the nature of the active mass used (CuO) causes the appearance of oxygen during the nitrogen sweeping step. The particles can therefore be used indifferently in a CLC or CLOU type process.

After testing, the sample underwent a very significant attrition, with almost all the particles having a size of less than 100 μηη, as can be seen in the diagram of the FIG. 1C, representing the particle size distribution (μηι) of the oxygen carrier solid according to this example before (curve 10) and after (curve 1 1) its use in a CLC process, that is to say before and after the aging test according to Example 1.

SEM slices on a polished section of the particles after the aging test according to Example 1, such as the plate of FIG. 1D, show that the constitutive aluminic matrix of the particles did not resist the 250 successive redox cycles. Most of the particles are actually in the form of small fragments (a few tens of μηη). In addition, additional SEM-EDX analyzes show that the finest particles observed (some μηη in size) consist almost exclusively of copper and oxygen. This example shows that when the active mass is deposited on a purely mesoporous alumina, the accumulation of redox cycles leads to the cracking of said aluminum matrix, and to the migration of copper within the aluminum matrix to form aggregates composed essentially of copper. The mechanical strength of the cracked ceramic matrix is then insufficient and the life of the particles is drastically reduced.

Example 3: Carbohydrate carrying solid CuO / Silica Alumina at 5% SiO 2

According to this example 3, an oxygen-carrying solid is formed from silicified alumina at 5% of SiO ₂ as a support matrix for an active oxide-reduction mass of copper oxide (s) (CuO and CuAl ₂ O ₄ ). The siliceous alumina used is Siralox 5 sold by Sasol and which contains 5% by weight of silica (SiO ₂ ). The particle size distribution indicates Dv ₁₀ = 60 μηη, Dv ₅₀ = 89 μηη and Dv ₉₀ = 131 μηη. The pore volume measured by mercury porosimetry of the alumino-silicic support is 0.549 ml / g, and the pore size distribution is between 5 and 30 nm, centered on 13 nm. The macroporous volume is 0.033 ml / g, ie 6% of the total pore volume measured by mercury porosimetry.

The nitrogen adsorption isotherm of Siralox 5 makes it possible to measure a specific surface area of 173 m ² / g, a microporous volume (pore size <2 nm) and a mesoporous volume (2 nm <pores <50 nm) of 0.601 ml. /boy Wut.

240 g of siliceous alumina were impregnated according to the dry impregnation method, with 109 g of copper nitrate trihydrate in aqueous solution. After drying at 120 ° C and calcination at 1000 ° C. for 12 hours, a solid containing 13% by weight of CuO equivalent is obtained. The crystallographic phases detected by XRD are δ-ΑΙ ₂ 0 ₃ , θ-ΑΙ ₂ 0 ₃ , CuAl ₂ O ₄ and CuO. The SEM backscattered electron (a) on polished section and the EDX (b) mapping of FIG. 2C show that the copper is relatively well dispersed inside the particles, but in a less homogeneous manner than in example 2.

The pore volume of the particles measured by mercury porosimetry is 0.340 ml / g, of which 0.029 ml / g (8.5%) is due to macroporosity. The pore size distribution is between 7 and 50 nm and centered on 15 nm, as can be seen in the diagram of FIG. 2A representing the volume of mercury injected Vi (ml / g) in the porosity, as well as the ratio dV / dD, as a function of the pore diameter (nm), for the oxygen carrier solid according to this example. The particles after impregnation / calcination are essentially mesoporous.

The specific surface area measured by nitrogen adsorption is 77 m ² / g.

The oxygen carrier solid according to Example 3 was aged under the conditions described in Example 1.

The conversion of methane is stable, of the order of 60% over the entire test (Figure 2B).

It should be noted that the nature of the active mass used (copper oxides) causes the appearance of oxygen during the nitrogen sweeping step. The particles can therefore be used indifferently in a CLC or CLOU type process. The partial conversion of methane relative to Example 2 is not a problem with respect to the CLC or CLOU process on an industrial scale, the total conversion of the fuel can be achieved by modifying the residence times of the particles. , gas velocities and / or inventory in the reduction reactor.

The size distribution of the particles after the aging test is similar to that of the material before testing, which indicates a better mechanical strength of the alumina-silica matrix compared to the particles on pure alumina.

It is observed, however, that almost all of the initially dispersed copper within the particles has migrated towards the periphery of said particles to form porous zones essentially containing copper and a little aluminum, as can be seen in FIG. SEM image of Figure 2D. The mechanical strength of these zones, although porous, is sufficient so that the layers and aggregates formed are still in most cases integral with the initial alumina-silica support under the conditions described in Example 1. However, it is not It is possible to use this type of particle in a circulating fluidized bed on an industrial scale, where higher gas velocities and inevitable attrition by abrasion would result in the rapid elimination of all the copper accumulated at the periphery.

According to the EDX mapping measurements made, the zone of particles whose morphology is relatively unchanged with respect to the initial silica-alumina consists mainly of alumina and contains only traces of copper, as well as almost all of silicon. The presence of silicon in the ceramic matrix thus makes it possible to stabilize said ceramic matrix. However, all the copper initially well dispersed in the mesoporous matrix migrated to the periphery of the particles during successive redox cycles.

EXAMPLE 4 CuO / Celsiane Oxygen-Bearing Solid According to this example 4, an oxygen-carrying solid is formed comprising a ceramic matrix of Celsiane in which is dispersed an oxidation-reduction active mass of oxide (s). of copper.

The oxygen-carrying solid according to this example is obtained from a macroporous zeolite precursor BaX (BaX means zeolite X exchanged with barium), starting from the following steps: an agglomeration of NaX zeolite crystals, of atomic ratio Si / Al = 1.25 and with a mean diameter in number equal to 1.5 μηη, with kaolinite and silica, and shaped by granulation, followed by drying and then calcination at 550 ° C. nitrogen for 2 h, and sieving the agglomerates obtained so as to recover particles having a particle size of between 200 and 500 μηη, with a median volume diameter around 350 μηη. a zeolitization of the binder by contact of the obtained particles placed in a glass reactor with an aqueous solution of sodium hydroxide concentration 100 g / l at a temperature of 100 ° C with stirring for 3 h. The particles are then washed in 3 successive water-washing operations followed by reactor emptying. The effectiveness of the washing is ensured by measuring the final pH of the washing water which is between 10 and 10.5. barium exchange using a solution of 0.5 M barium chloride at 95 ° C in four steps. At each step, the volume ratio of solution to solid mass is 20 ml / g and the exchange is continued for 4 hours each time.

Between each exchange, the solid is washed several times in order to rid it of excess salt.

The barium exchange rate of this zeolite precursor is 95%.

The pore volume of the precursor of the shaped ceramic matrix, which is a particulate macroporous BaX zeolite material measured by mercury porosimetry, is 0.206 ml / g. The macroporous volume (pore size> 50 nm) is 0.191 ml / g, and the mesoporous volume (3.65 nm <pore <50 nm) is 0.015 ml / g. The size distribution of the macropores is between 100 nm and 1000 nm, centered on 330 nm. This distribution is visible in FIG. 3C, where Vi Z refers to the porosity of the precursor of the ceramic matrix (macroporous BaX zeolite material formed).

The nitrogen adsorption isotherm of this precursor of the ceramic matrix makes it possible to measure a specific surface area of 676 m ² / g, a microporous volume (pore size <2 nm) of 0.24 ml / g and a mesoporous volume ( 2 nm <pores <50 nm) of 0.04 ml / g.

120 g of this precursor of the ceramic matrix were dry impregnated with 57 g of copper nitrate trihydrate in aqueous solution. After drying at 120 ° C. and calcination at 800 ° C. for 12 hours, an oxygen-carrying solid according to the invention containing 13.5% by weight of CuO is obtained. The particle size distribution, measured by liquid phase laser particle size, indicates Dv10 = 199 μηη, Dv50 = 341 μηη and Dv90 = 534 μηη.

After calcination at 800 ° C, the initial zeolite structure is completely destroyed. Tenorite (CuO) and two celsian polymorphs (hexagonal and monoclinic) are detected by XRD, as shown on the X-ray diffractogram of Figure 3A. In this figure, A on the abscissa corresponds to the angle 2Θ (in degrees) and Cps on the ordinate represents the number of strokes during the measurement. The intensity of the diffraction peaks of the hexagonal form of celsiane (H) is higher than that measured for the monoclinic form (M). The porous volume of the oxygen-carrying solid according to the invention, measured by mercury porosimetry, is 0.153 ml / g. The macroporous volume (pore size> 50 nm) is 0.145 ml / g (94.8%), and the mesoporous volume is 0.008 ml / g. The size distribution of the macropores is between 100 nm and 4000 nm, centered on 400 nm. The grain density is 2086 kg / m ³ . This distribution is visible in FIG. 3C, where Vi S refers to the porosity of the initial oxygen-carrying solid (before aging test).

The specific surface area of the oxygen carrier according to the invention, measured by nitrogen adsorption according to the BET method, is 5 m ² / g.

SEM analysis (Figure 3B, SEM backscattered electron (a) and EDX mapping in (b)) on polished section shows that the distribution of copper inside the particles is relatively homogeneous, in the form of nodules size between 0.1 μηη and 5 μηη dispersed in the macroporosity.

The aging of the particles in a batch fluidized bed was carried out according to the same protocol as in Example 1. The conversion of methane to H ₂ 0 and C0 ₂ is stable, of the order of 61% over the entire test.

The partial conversion of methane relative to Example 2 is not a problem with respect to the CLC or CLOU process on an industrial scale, the total conversion of the fuel can be achieved by modifying the residence times of the particles. , gas velocities and / or inventory in the reduction reactor.

As in Example 3, the particle size distribution after the aging test is similar to that of the pre-test material. Contrary to the observations of Example 3, the copper distribution after 250 cycles in a batch fluidized bed within the particles of the oxygen carrier according to the invention remains generally homogeneous, with a markedly minimized tendency for copper to migrate towards the periphery of the particles, as visible on the SEM image (a) and the EDX map (b) of the 3D figure. The presence of cuprous nodules of size between 0, 1 μηι and 5 μηι in the porosity. This texture is clearly visible in the SEM backscattered electron micrograph of FIG. 3E relating to a detail of a particle of the oxygen-carrying solid after aging.

The main crystalline phases detected by DRX after aging are tenorite (CuO) and monoclinic celsiane. Some very low intensity peaks characteristic of hexagonal celsiane and copper aluminate (CuAl ₂ 0 ₄ ) are also present.

The pore volume of the particles measured by mercury porosimetry decreased by 20% (0.15 ml / g) during aging, and the pore size increased (pore size distribution centered on 600 nm). A slight sintering of the Celsian matrix therefore took place. However, in view of these results, and compared to the other examples, the oxygen carrier solid according to this example 4 has a good sintering resistance.

The oxygen-carrying solid after 250 oxidation-reduction cycles nevertheless retains a pore size distribution and a pore volume sufficient to limit the migration of copper within the particles. The morphological evolution of the oxygen-carrying solid according to the invention (porosity and distribution of copper) thus makes it possible to envisage the prolonged use of these particles in an industrial process in a circulating fluidized bed.

Example 5: CuO / Nepheline-carrying solid oxygen

According to this example 5, an oxygen carrier solid is formed comprising a ceramic matrix of nepheline (feldspathoid) within which is dispersed an active oxide redox oxide (s) active mass.

The oxygen-carrying solid according to this example is obtained from a macroporous zeolite precursor NaX, starting from the following steps: an agglomeration of NaX zeolite crystals, with an Si / Al = 1, 25 atomic ratio, and a mean diameter of a number equal to 1.5 μηη, with kaolinite and silica, and shaped by granulation, followed by drying and then calcination at 550 ° C. under a stream of nitrogen for 2 h, and sieving of agglomerates obtained so as to recover particles of particle size between 200 μηη and 500 μηη, with a median volume diameter around 350 μηη. The zeolitization steps of the binder and exchange with barium have not been realized.

The pore volume of the precursor of the ceramic matrix (zeolite material macroporous NaX) shaped, measured by mercury porosimetry, is 0.336 ml / g. The macroporous volume (pore size> 50 nm) is 0.296 ml / g, and the mesoporous volume is 0.040 ml / g. The size distribution of the macropores is between 100 nm and 1000 nm, centered on 330 nm. This distribution is visible in FIG. 4A where Vi Z refers to the porosity of the precursor of the ceramic matrix.

The nitrogen adsorption isotherm of the precursor of the ceramic matrix makes it possible to measure a specific surface area of 749 m 2 / g, a microporous volume (pores <2 nm) of 0.260 ml / g and a mesoporous volume (2 nm <pores <50 nm) of 0.12 ml / g.

105 g of the precursor of the ceramic matrix were impregnated dry with 43.9 g of copper nitrate trihydrate in aqueous solution. After drying at 120 ° C. and calcining at 800 ° C. for 12 hours, a solid containing 12% by mass of CuO equivalent on silica-alumina is obtained. The particle size distribution, measured by liquid phase laser granulometry, indicates Dv10 = 156 μηι, Dv50 = 286 μηι and Dv90 = 458 μηι.

After calcination at 800 ° C., tenorite (CuO) and nepheline of formula Na ₃ . ₆ AI ₃ . ₆ Si4.4Oi ₆ are the only two phases detected by DRX. SEM images on polished section, such as the snapshot of FIG. 4B, show a significant cracking of the nepheline matrix in comparison with the particles of example 4, and a copper accumulation at the periphery of the particles. The formation of micrometric copper nodules in the macroporosity of the matrix is also observed.

The pore volume of the particles of Example 5, measured by mercury porosimetry, is 0.103 ml / g, with a wide pore size distribution (130 nm to 4.7 μm) centered on 750 nm. The pore volume consists of 100% macropores. This distribution is visible in FIG. 4A, where Vi refers to the porosity of the initial oxygen-carrying solid (before aging test).

The aging of the particles in a batch fluidized bed was carried out according to the same protocol as in Example 1.

The conversion of methane to water and carbon dioxide is stable, but only around 30% over the entire test. The partial conversion of methane relative to Example 2 is not a problem with respect to the CLC or CLOU process on an industrial scale, the total conversion of the fuel can be achieved by modifying the residence times of the particles. , the gas velocities and / or the inventory in the reduction reactor, but the solid according to Example 5 is less efficient than that of Example 4 and would require a higher inventory.

In spite of the fluidization, the solid slightly increased in mass during the test (a friable agglomerate is observed during the unloading of the reactor). After grinding (easy) of the agglomerate in the reactor, the measurement of the particle size distribution shows that a high proportion of fine particles (9% by weight of particles of size <100μηΊ) has been created, probably because severe cracking observed at the calcination step at 800 ° C. The absence of zeolitization of the binder after shaping is probably the cause of the lower mechanical strength of the particles.

Tenorite and nepheline are still predominantly present, and the main X-ray diffraction lines characteristic of quartz, cristobalite and copper aluminate CuAlO _{4 are also} observed. The very low relative intensity of these lines indicates that these three phases are in the minority.

SEM images on polished section of the particles after aging show two distinct morphologies of the particles (Figure 4C, SEM images in backscattered electrons (a) and (b)): a significant densification of the nepheline matrix is observed on certain particles, which resulted in a large migration of copper towards the periphery of the particles (SEM image (b) of FIG. 4C). The crust observed around these particles is probably at the origin of the caking observed after 250 cycles. Part of the copper present in these particles coalesced inside the very large pores formed during the test at the gas / solid interface.

The second morphology consists of macroporous particles in which copper forms micrometric nodules (SEM image (a) of Figure 4C).

The relatively low melting temperature of nepheline (1230 ° C) relative to celsian (1760 °) may be responsible for the higher densification observed. It is likely that some of the copper trapped in particles with a dense matrix is not accessible to gas, hence the conversion of methane lower than in Example 4. In addition to decreased reactivity compared to Example 4, the formation of a metal oxide crust at the periphery of a high proportion particles makes the use of this type of particles unthinkable in a fluidized bed circulating on an industrial scale (risk of agglomeration and loss of copper by attrition too large).

The pore volume of the particles measured by mercury porosimetry (0.088 ml / g) is of the same order of magnitude as before, as is the pore size distribution (1 10 nm - 4.7 μm).

EXAMPLE 6 CuO / Albite Oxygen-Bearing Solid According to this example 6, an oxygen-carrying solid is formed comprising a ceramic matrix of albite (feldspathoid) within which an oxidation-reduction active mass is dispersed. copper oxide (s).

The oxygen-carrying solid according to this example is obtained from a macroporous zeolite precursor NaY from the following stages: an agglomeration of zeolite crystals NaY, of structural type FAU identical to zeolites X and LSX, but of atomic ratio If / Al = 3, that is to say higher than the zeolite X or the zeolite LSX, and of average diameter in number equal to 0.7 μηη, with kaolinite and silica, and shaping by granulation, followed by drying and then calcination at 550 ° C. under a stream of nitrogen for 2 h, and sieving of the agglomerates obtained so as to recover particles having a particle size of between 200 μηη and 500 μηη, with a diameter median in volume around 350 μπι. a zeolitization of the binder by contact of the obtained particles placed in a glass reactor with an aqueous solution of sodium hydroxide concentration 100 g / l at a temperature of 100 ° C with stirring for 3 h. The particles are then washed in three successive operations of washing with water followed by the emptying of the reactor. The effectiveness of the washing is ensured by measuring the final pH of the washing water which is between 10 and 10.5.

The pore volume of the precursor of the shaped ceramic matrix (macroporous NaY zeolite material), measured by mercury porosimetry, is 0.376 ml / g. Volume macroporous (pore size> 50 nm) is 0.319 ml / g, and the mesoporous volume (3.65 nm <pores <50 nm) is 0.057 ml / g. The size distribution of the macropores is between 100 nm and 1000 nm, centered on 330 nm. This distribution is visible in Figure 5A where Vi Z refers to the porosity of the precursor of the ceramic matrix. The precursor nitrogen adsorption isotherm of the ceramic matrix makes it possible to measure a specific surface area of 676 m ² / g, a microporous volume (pore size <2 nm) of 0.24 ml / g and a mesoporous volume (2 nm). <pores <50 nm) of 0.04 ml / g.

108 g of this precursor of the ceramic matrix were dry impregnated with 44 g of copper nitrate trihydrate in aqueous solution. After drying at 120 ° C. and calcining at 800 ° C. for 12 hours, a solid containing 1.18% by weight of CuO equivalent is obtained.

After calcination at 800 ° C., tenorite (CuO), an amorphous phase and quartz are detected by XRD. Some diffraction lines of very low intensity, indicating a beginning of crystallization of a new phase, can not be definitively attributed.

The particle size distribution indicates Dv10 = 104 μηη, Dv50 = 212 μηη and Dv90 = 356 m.

The porosity of the particles of the oxygen-bearing solid is only 9% and the pore size distribution is very wide (from 30 nm to 5000 nm, or even Figure 5A curve Vi S), reflecting the presence of very large cavities created during the calcination and observed by SEM, as well as a densification of the amorphous matrix of silica-alumina (SEM image of Figure 5B). The total pore volume is 0.043 ml / g. The macroporous volume (pore size> 50 nm) is 0.038 ml / g (88.4%), and the mesoporous volume is 0.005 ml / g. SEM-EDX mapping on a polished section shows that most of the copper coalesced as micrometric nodules inserted into the matrix. Strong cracking occurred inside the particles. The aging of the particles in a batch fluidized bed was carried out according to the same protocol as in Example 1.

There is a particle activation, the conversion of methane increasing gradually from 6% in the second cycle to 14% at 250 ^th cycle. The solid was slightly encrusted during the test. After grinding (easy) of the agglomerate in the reactor, the Size distribution of the particles after the aging test is similar to that of the material before testing.

The porosity of the particles is only 4%, consisting essentially of large cavities still present within the particles (size centered around 3700 nm). The low conversion of methane can be directly related to the lack of porosity of the matrix, which encapsulates a large proportion of copper and makes it inaccessible to different gases. The gradual increase in conversion is probably due to the migration of copper to the periphery of the particles over the redox cycles. In fact, the SEM analysis after aging shows that a copper crust has accumulated on the surface of the particles during the test (SEM image of FIG. 5C). This accumulation of copper on the surface is responsible for the agglomeration of the particles. A significant proportion of the copper is still trapped inside the matrix at the end of the test.

The XRD analysis shows that the initially amorphous matrix formed a crystalline phase, the albite (NaAISi ₃ 0 ₈ ), whose melting point (1120 ° C.) is weak relative to the celsiane. The presence of tenorite (CuO), quartz, cuprite (Cu ₂ O) and traces of nepheline is also observed.

The formation of a copper crust at the periphery of the particles and the too low porosity of the albite matrix makes the use of this type of particles unthinkable in a circulating fluidized bed on an industrial scale. Example 7: CuO / Slawsonite oxygen carrier solid

According to this example 7, an oxygen carrier solid is formed comprising a slawsonite ceramic matrix (feldspar) in which is dispersed an active oxide redox oxide (s) active mass.

The oxygen carrier solid according to this example is obtained from a macroporous zeolite precursor SrLSX (SrLSX means zeolite LSX exchanged with strontium), from the following steps: an agglomeration of LSX zeolite crystals, of atomic ratio Si / Al = 1 and with a mean diameter in number equal to 1.5 μηη, with kaolinite and silica, and shaped by granulation, followed by drying and then calcination at 550 ° C. nitrogen stream for 2 h, and sieving the agglomerates obtained so as to recover particles with a particle size of between 200 μηη and 500 μηη, with a median volume diameter around 350μηη. a zeolitization of the binder by contact of the obtained particles placed in a glass reactor with an aqueous solution of sodium hydroxide concentration 100 g / l at a temperature of 100 ° C with stirring for 3 h. The particles are then washed in 3 successive operations of washing with water followed by the emptying of the reactor. The effectiveness of the washing is ensured by measuring the final pH of the washing water which is between 10 and 10.5. an exchange with strontium by means of a solution of 0.5 M strontium chloride at 95 ° C. in 4 steps. At each step, the volume ratio of solution to solid mass is 20 ml / g and the exchange is continued for 4 hours each time. Between each exchange, the solid is washed several times in order to rid it of excess salt. The strontium exchange rate of this zeolite precursor is 94%.

The pore volume of the precursor of the shaped ceramic matrix (macroporous SrLSX zeolite material), measured by mercury porosimetry, is 0.195 ml / g. The macroporous volume (pore size> 50 nm) is 0.183 ml / g, and the mesoporous volume is 0.012 ml / g. The size distribution of the macropores is between 50 nm and 950 nm, centered on 300 nm. This distribution is visible in Figure 6A where Vi Z refers to the porosity of the precursor of the ceramic matrix.

122 g of this zeolite were dry impregnated with 51 g of copper nitrate in aqueous solution. After drying at 120 ° C. and calcination at 800 ° C. for 12 hours, an oxygen-carrying solid according to the invention containing 12% by weight of CuO is obtained. The size distribution of the particles, measured by liquid-phase laser particle size distribution, indicates Dv10 = 195 μπι, Dv50 = 320 μηι and Dv90 = 495 μπι.

After calcination at 800 ° C., the initial zeolite structure is completely destroyed. Tenorite (CuO) and two polymorphs of slawsonite (RIAS ₂ Si ₂ 0 ₈ and hexagonal Sro. AluSi2.3O8 monoclinic ₈₎ are detected by XRD. The intensity of the diffraction peaks of the two polymorphs is similar. The porous volume of the oxygen carrier solid according to the invention, measured by mercury porosimetry, is 0.093 ml / g. The macroporous volume (pore size> 50 nm) is 0.091 ml / g, and the mesoporous volume is 0.002 ml / g. The size distribution of the macropores is between 50 nm and 3500 nm, centered on 350 nm. This distribution is visible in FIG. 6A where Vi S refers to the porosity of the initial oxygen-carrying solid (before aging test).

The specific surface area of the oxygen carrier according to the invention, measured by nitrogen adsorption according to the BET method, is 3 m ² / g.

SEM-EDX analysis on a polished section shows that the distribution of copper inside the particles is relatively homogeneous in the form of nodules of size between 0.1 μηη and 5 μηη dispersed in the macroporosity.

The conversion of methane to water and carbon dioxide is stable, of the order of 59% over the entire test.

As in Example 3, the particle size distribution after the aging test is similar to that of the pre-test material. Contrary to the observations of Example 3, the copper distribution after 250 cycles in a batch fluidized bed within the particles of the oxygen carrier according to the invention remains generally homogeneous, with a markedly minimized tendency for copper to migrate towards the periphery of the particles. The presence of copper-bearing nodules is still observed between 0, 1 μηη and 5 μηη in the porosity. FIG. 6B, which is an SEM image of a portion of a particle of the oxygen-carrying solid after aging, shows this texture.

The main crystalline phases detected by DRX after aging are tenorite (CuO) and monoclinic slawsonite. Some very weak peaks characteristic of hexagonal slawsonite and copper aluminate (CUAI2O4) are also present.

The porous particle volume measured by mercury porosimetry decreased by 23% (0.072 ml / g) during aging, and the pore size increased (pore size distribution centered on 550 nm). A slight sintering of the slawsonite matrix therefore took place. The oxygen-carrying solid after 250 oxidation-reduction cycles nevertheless retains a pore size distribution and a pore volume sufficient to limit the migration of copper within the particles.

Claims

Particle-carrying oxygen solid for a process for the combustion of a hydrocarbon feedstock by oxido-reduction in a chemical loop, comprising: an oxidation-reduction active mass constituting between 5% and 75% by weight of said carrier solid oxygen, said oxidation-reduction active mass comprising a metal oxide or a mixture of metal oxides and being capable of transporting oxygen in the chemical-loop oxidation-reduction combustion process; a ceramic matrix in which said oxidation-reduction active mass is dispersed, said ceramic matrix constituting between 25% and 95% by weight of said oxygen-carrying solid, and said ceramic matrix comprising between 60% and 100% weight of at least one feldspar or feldspathoid having a melting temperature above 1500 ° C and between 0% and 40% of at least one oxide; a porosity such that: the total pore volume of the oxygen-carrying solid, measured by mercury porosimetry, is between 0.05 and 0.9 ml / g, the pore volume of the macropores constitutes at least 10% of the total pore volume oxygen-carrying solid; the size distribution of the macropores within the oxygen carrier solid, measured by mercury porosimetry, is between 50 nm and 7 μηη.

An oxygen carrier solid according to claim 1, wherein the total pore volume of the oxygen-bearing solid is from 0.1 to 0.5 ml / g.

Oxygen carrier solid according to one of claims 1 and 2, wherein the pore volume of the macropores constitutes at least 50% of the total pore volume of the oxygen-carrying solid.

Oxygen carrier solid according to one of the preceding claims, wherein the size distribution of the macropores in the oxygen carrier solid is between 50 nm and 4 μηη.

5. Oxygen carrier solid according to one of the preceding claims, wherein said active redox active mass comprises at least one metal oxide included in the list consisting of the oxides of Fe, Cu, Ni, Mn and Co, a perovskite having redox properties, preferably a perovskite of formula CaMnO ₃ , a metal aluminate spinel having redox properties, preferably a metal aluminate spinel of formula CuAl ₂ O ₄ or a Cuprospinelle of formula CuFe ₂ 0 ₄ .

6. Oxygen carrier solid according to one of the preceding claims, wherein said active redox active mass comprises at least one copper oxide.

7. Oxygen carrier solid according to one of the preceding claims, wherein said at least feldspar or feldspathoid has a melting temperature greater than 1700 ° C.

An oxygen carrier solid according to claim 7, wherein said at least one feldspar or feldspathoid of said ceramic matrix is a feldspar selected from the list consisting of celsiana, slawsonite, anorthite, or a feldspathoid being the kalsilite, and is preferably celsiane 9. Oxygen carrier solid according to one of the preceding claims, wherein said at least one oxide of the ceramic matrix is selected from the list consisting of alumina, metal aluminates, silica, silicates, aluminosilicates, titanium dioxide, perovskites, zirconia.

10. Oxygen carrier solid according to one of the preceding claims, wherein the particles have a particle size such that more than 90% of the particles have a size between 50 μηη and 600 μηη.

Process for the preparation of an oxygen-carrying solid according to one of Claims 1 to 10, comprising the following steps:

(A) the preparation of a precursor of a ceramic matrix comprising: a1) the preparation of a macroporous zeolite material, said material comprising zeolite crystals with a mean diameter of less than or equal to 3 μηη, and preferably of average diameter in number between 0.4 μηη and 2 μηη; and a2) a cationic exchange of said macroporous zeolite material with a solution of precursor ions, the precursor ions being chosen to form a feldspar or feldspathoid with a melting temperature> 1500 ° C. of the ceramic matrix at the end of the step ( D), said cationic exchange being followed by a washing of said macroporous zeolite material to obtain said precursor of the ceramic matrix;

(B) impregnating said precursor of the ceramic matrix obtained in step (A) with a precursor compound of an oxidation-reduction active mass;

(C) forming particles of the precursor of the ceramic matrix during step (a1) or at the end of step (B);

(D) drying the precursor of the impregnated ceramic matrix in particle form obtained at the end of all of the steps (A), (B) and (C); and

12. Process for preparing an oxygen-carrying solid according to claim 11, in which step a1) comprises:

- a'1) agglomeration of zeolite crystals with a clay binder to form a zeolite agglomerate; - a'2) the shaping of the zeolite agglomerate obtained in step a'1) to produce particles, followed by drying of said particles, and possibly followed by a sieving and / or cycloning step ;

- a'3) calcining the particles of the zeolite agglomerate obtained in step a'2) at a temperature between 500 ° C and 600 ° C to produce the macroporous zeolite material in particulate form;

13. Process for preparing an oxygen-carrying solid according to one of claims 1 1 and 12, wherein said zeolite crystals comprise at least one zeolite with an Si / Al molar ratio of between 1.00 and 1.5, preferably, said zeolitic crystals comprising at least one zeolite chosen from zeolites A, X, LSX and low-silica EMT, said low-silica EMT having a Si / Al ratio of between 1.0 and 1.4. 14. Process for preparing an oxygen-carrying solid according to one of claims 1 1 to 13, wherein the cationic exchange in step a2) is carried out with a solution comprising alkaline ions, preferably K +, or alkaline earth ions, and preferably with a solution comprising alkaline earth ions.

15. A process for preparing a solid oxygen carrier according to claim 14, wherein the cation exchange step a2) is carried out with a solution comprising ions selected from Ba ^2+, Sr ² * Ca ²⁺ , and preferably with a solution comprising Ba ²⁺ ions.

16. Process for preparing an oxygen-carrying solid according to one of claims 1 1 to 15, wherein step (A) further comprises a step a3) of heat treatment of the macroporous zeolite material obtained at step a2), said heat treatment comprising a drying step at a temperature of between 100 ° C and 400 ° C. 17. Process for preparing an oxygen-carrying solid according to one of claims 1 1 to 16, wherein in step (C) the precursor of the ceramic matrix is placed in the form of particles having a particle size such that more than 90% of the particles have a size of between 50 μηη and 600 μηη.

18. Process for preparing an oxygen-carrying solid according to one of claims 1 1 to 17, in which the impregnation in step (B) is carried out with an aqueous or organic solution containing at least one precursor compound. soluble copper, nickel, cobalt, iron or manganese, preferably with an aqueous solution containing at least one precursor compound of the oxidation-reduction active mass selected from the list consisting of nitrates of the following formulas: Cu (N0 ₃ ) ₂ .xH ₂ O, Ni (NO ₃ ) ₂ .xH ₂ O, Co (NO ₃ ) ₂ .xH ₂ O, Fe (NO ₃ ) ₃ .xH ₂ O, Mn (NO ₃ ) ₂ . xH ₂ 0.

19. Process for the preparation of an oxygen-carrying solid according to one of claims 1 1 to 18, in which the impregnation in step (B) is carried out in one or more successive stages, and preferably comprises intermediate stages of drying at a temperature between 30 ° C and 200 ° C and / or calcination at a temperature between 200 ° C and 600 ° C when the impregnation is carried out in several successive steps.

20. Process for the preparation of an oxygen-carrying solid according to one of claims 1 1 to 19, wherein the drying in step (D) is carried out under air or in a controlled atmosphere, at a temperature between 30.degree. ° C and 200 ° C, and preferably in air at a temperature between 100 ° C and 150 ° C.

21. A process for preparing an oxygen-carrying solid according to one of claims 1 1 to 20, wherein the calcination in step (E) is carried out in air between 450 ° C and 1400 ° C, preferably between 600 ° C and 1000 ° C, more preferably between 700 ° C and 900 ° C, and is carried out for a period of 1 to 24 hours, and preferably for a period of 5 to 15 hours. 22. Process for preparing an oxygen-carrying solid according to one of claims 1 1 to 21, wherein in step a1) the zeolite crystals are mixed with at least one oxide selected from the list consisting of alumina, metal aluminates, silica, silicates, aluminosilicates, titanium dioxide, perovskites, zirconia, and / or a pore-forming agent for increasing the macroporosity of the macroporous zeolite material.

23. A process for the combustion of a hydrocarbon feedstock by oxido-reduction in a chemical loop using an oxygen-carrying solid according to one of claims 1 to 10, or prepared according to the method according to one of claims 1 1 to 23.

24. A process for the combustion of a hydrocarbon feedstock by oxido-reduction in a chemical loop according to claim 23, preferably in which the oxygen-bearing solid circulates between at least one reduction zone and an oxidation zone both operating. in a fluidized bed, the temperature in the reduction zone and in the oxidation zone being between 400 ° C. and 1400 ° C., preferably between 600 ° C. and 1100 ° C., and more preferably between 800 ° C. and 1100 ° C.