The disclosure provides a tri-metallic ferrite oxygen carrier for the chemical looping combustion of carbonaceous fuels. The tri-metallic ferrite oxygen carrier comprises Cu.sub.xFe.sub.yMn.sub.zO.sub.4-δ, where Cu.sub.xFe.sub.yMn.sub.zO.sub.4-δ is a chemical composition. Generally, 0.5≦x≦2.0, 0.2≦y≦2.5, and 0.2≦z≦2.5, and in some embodiments, 0.8≦x≦1.2, y≦1.2, and z≧0.8. The tri-metallic ferrite oxygen carrier may be used in various applications for the combustion of carbonaceous fuels, including as an oxygen carrier for chemical looping combustion.

In accordance with one embodiment of the present disclosure, an oxygen carrying material may include a primary active mass, a primary support material, and a secondary support material. The oxygen carrying material may include about 20% to about 70% by weight of the primary active mass, the primary active mass including a composition having a metal or metal oxide selected from the group consisting of Fe, Co, Ni, Cu, Mo, Mn, Sn, Ru, Rh, and combinations thereof. The oxygen carrying material may include about 5% to about 70% by weight of a primary support material. The oxygen carrying material may include about 1% to about 35% by mass of a secondary support material.

Oxygen carriers for chemical looping and scalable methods of preparation thereof. Wet impregnation of active metal precursors into porous substrates, together with selective adsorption of the precursors on the pore surfaces, enables transition metal oxides derived from the precursors to disperse throughout the substrate, even at the nanoscale, without increased sintering or agglomeration. The porous substrate can be an oxide, for example SiO.sub.2. The oxygen carriers can comprise relatively large oxide loadings of over about 20 wt % and exhibit high reactivity over many regeneration cycles with substantially no loss in oxygen transport capacity or decrease in kinetics. The use of multiple transition metals, for example NiO in addition to CuO, can greatly enhance chemical looping performance.

The invention relates to an improved method for chemical-looping combustion of a solid hydrocarbon-containing feed using a particular configuration of the reduction zone with: a first reaction zone R1 operating under dense fluidized bed conditions; a second reaction zone R2; a fast separation zone S3 for separation of the unburnt solid feed particles, of fly ashes and of the oxygen-carrying material particles within a mixture coming from zone R2; fumes dedusting S4; a particle stream division zone D7, part of the particles being directly recycled to first reaction zone R1, the other part being sent to an elutriation separation zone S5 in order to collect the ashes through a line 18 and to recycle the dense particles through a line 20 to first reaction zone R1. The invention also relates to a chemical-looping combustion plant allowing said method to be implemented.

The invention relates to a process and to a unit for chemical looping oxidation-reduction combustion of a hydrocarbon feed, wherein heat exchanges are controlled through a level variation of a dense fluidized bed of active mass particles in an external heat exchanger (E1, E2), positioned on a transport line carrying particles circulating between a reduction zone (210) and an oxidation zone (200) for the particles in the chemical loop. The bed level variation is allowed through controlled application of a pressure drop on a fluidization gas outlet in the heat exchanger, said pressure drop being compensated by the level variation of an active mass particle bed in a reservoir zone provided on the particle circuit in the chemical loop.

The invention relates to a plant and to a method for chemical looping oxidation-reduction combustion of a gaseous hydrocarbon feed, for example natural gas essentially containing methane. According to the invention, catalytic pre-reforming of the feed is performed in a pre-reforming zone comprising a fixed reforming catalyst, while benefiting from a heat transfer between the reduction or oxidation zone of the chemical loop and the pre-reforming zone adjoining the reduction or oxidation zone. Pre-reforming zone (130) and oxidation zone (110) or pre-reforming zone (130) and reduction zone (120) are thus thermally integrated within the same reactor (100) while being separated by at least one thermally conductive separation wall (140).

The invention relates to a method and to a plant for chemical looping oxidation-reduction combustion (CLC) of a gaseous hydrocarbon feed, for example natural gas essentially containing methane. According to the invention, catalytic reforming of the feed is performed within the reduction zone where combustion of the feed is conducted on contact with an oxidation-reduction active mass in form of particles. The reforming catalyst comes in form of untransported fluidized particles within the reduction zone. The catalyst thus confined in the reduction zone does not circulate in the CLC loop.

The invention relates to a method and to a plant for chemical looping oxidation-reduction combustion (CLC) of a gaseous hydrocarbon feed, for example natural gas essentially containing methane. According to the invention, catalytic steam reforming of the feed is performed between two successive feed combustion steps on contact with an oxidation-reduction active mass in form of particles. The reforming catalyst is arranged in a fixed bed in an intermediate reforming zone (130) between the two reduction zones (120, 140) where the two combustion steps are conducted.

FIG. 2 to be published.

A calcium looping combustion process for sour gas combustion comprising a system that includes several reaction zones. The system is configured to provide oxygen transfer media production, generation of a syngas product stream, and in-situ H.sub.2S removal from the sour gas. The system is also configured such that the calcium-based transfer media and the calcium-based oxygen carrier are reproduced via reactions in another reaction zone, and recirculated in the system.

An improved chemical looping combustion (CLC) process and system includes a hopper containing oxygen carrier particles, e.g., metal oxides, that are gravity fed at a controlled rate of flow from the hopper into (a) a generally vertical downflow reactor where they are mixed with all of the hydrocarbon fuel feed to the system and (b) into one or more standpipes that are in communication with a plurality of staged fluidized reactor beds, the amount of the oxygen carrier particles introduced into the system being stoichiometrically predetermined to produce a syngas mixture of H.sub.2 and CO.sub.2; or to complete combustion of the fuel to CO.sub.2 and water vapor, thereby permitting capture of a majority of the CO.sub.2 produced in an essentially pure form.