Novel Tri-Metallic Ferrite Oxygen Carriers Enhance Chemical Looping Combustion

Fri, 06/01/2018 - 12:00

USPN 9,797,594

Opportunity

A patented technology invented at the U.S. Department of Energy’s National Energy Technology Laboratory enhances chemical looping combustion by providing tri-metallic ferrite oxygen carriers that offer greater durability and better reactivity than traditional oxygen carriers. Tri-metallic ferrite oxygen carriers also eliminate agglomeration issues, improve reduction rates, and offer similar costs when compared to traditional oxygen carriers, with convenient preparation using readily available materials. This technology is available for licensing and/or further collaborative research from NETL.

Challenge

Overview

Oxy-combustion power generation provides oxygen to the combustion process by separating oxygen from air. Chemical looping systems take advantage of oxygen internal to the process, cutting the large capital, operating, and energy costs associated with oxygen generation. However, the development of robust oxygen carriers is critical for the efficient operation and adoption of CLC technology.

NETL researchers have developed novel tri-metallic ferrite oxygen carriers that comprise Cu_xFe_yMn_zO_4-8 – where Cu_xFe_yMn_zO_4-8is a chemical composition with generally 0.5≤x≤2.0, 0.2≤y≤2.5, and 0.2≤z≤2.5 – for CLC of solid fuels such as coal, pet coke, and biomass. The tri-metallic ferrite oxygen carrier is used by delivering it to a fuel reactor and mixing it with a carbon-based fuel at a reducing temperature, which reduces a portion of the carrier and oxidizes a portion of the fuel. Within the fuel reactor, the tri-metallic ferrite carrier interacts with the fuel and generates a reduced carrier. The reduced carrier subsequently enters an oxidation reactor, where it is infused with oxidizing gas to produce a re-oxidized carrier through an oxidizing reaction. The re-oxidized carrier, which comprises comprise Cu_xFe_yMn_zO_4-8, may then be returned to the fuel reactor for a cyclic operation.

CLC offers a major advantage over conventional coal combustion by directly producing a concentrated stream of CO₂ without expending the significant energy required for CO₂ separation. This NETL technology offers numerous advantages over traditional oxygen carriers for coal CLC. Tri-metallic ferrites perform better when compared to Fe₂O₃, demonstrating high and stable reactivity over multiple reduction/oxidation cycles and high attrition resistance. Ferrite-based oxygen carriers also display a low tendency to agglomerate at high temperatures, as with CuO. These metal ferrites can be produced using readily available materials at a cost comparable to Fe₂O₃ and CuO oxygen carriers.

Advantages

Improved reduction/oxidation rates, durability and reactivity compared to Fe₂O₃
Eliminates agglomeration issues associated with CuO
Stable at high temperatures and over multiple oxidation-reduction cycles
Can be produced using readily available materials at comparable cost to standard oxygen carriers
Carriers are environmentally benign

Applications

Chemical looping combustion of coal
Chemical looping gasification of coal to produce synthesis gas
Combustion/gasification processes using biomass, pet coke, and other solid fuels

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