Henrik Leion

Chalmers University of Technology · Chemistry and Chemical Engineering

The greenhouse gas emissions from the boiler of pulp and paper industries can be minimized by adapting chemical looping combustion (CLC) technology. This work aims to analyze the energy, exergy, economic, and exergoeconomic performance of an industrial scale CLC plant for district heat and electricity generation using waste bark from the paper and...

Steel converter slag, also called LD slag, is a material that has been suggested for use as a low-cost oxygen carrier for chemical looping applications. Low-cost oxygen carriers are especially relevant for the conversion of solid fuels, which may contain large amounts of reactive ashes. Ash may limit the lifetime of the bed material, which is why a...

Chemical Looping Combustion (CLC) has been found to be a better alternative in converting Municipal Solid Waste (MSW) to energy and has the potential to reduce the generation of dioxins due to the inhibition of the de-novo synthesis of dioxins. This study comprehensively reviews the experimental studies of CLC of MSW, the oxygen carriers, reactor t...

Biomass conversion with carbon capture and storage (Bio‐Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical‐looping combustion (CLC) is examined in which the CO2 is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen ca...

Iron sand as an industrial by-product has a reasonable iron content (35 wt% Fe) and low economical cost. The reactivity of iron sand as an oxygen carrier was examined in a bubbling fluidized bed reactor using both gaseous and solid fuels at 850–975 °C. Pre-reductions of iron sand were performed prior to fuel conversion to adapt the less-oxygen-requ...

Oxygen carriers, in the form of metal oxide particles, are bed materials that transport oxygen in solid form in fluidized bed applications, such as in chemical-looping applications. In biofuel applications, it is well known that alkali from the fuel ash can react with the bed material and cause, among other operation issues, agglomeration. When usi...

One of the most essential features of an oxygen carrier is its ability to be oxidized and reduced in order to transfer oxygen in a chemical looping system. A highly reduced oxygen carrier can experience multiple performance issues, such as decreased reactivity, agglomeration, and defluidization. This is crucial for processes that require limited ox...

Chemical looping combustion (CLC) is a novel technology for heat and power generation with inherent CO2 capture. Using biomass in CLC (bio-CLC), negative CO2 emissions can be attained. Biomass usually contains high content of alkalis (mainly K and Na) which can be problematic in the process, such as potential alkali-bed interaction, and this is the...

Oxygen carriers used in chemical looping processes operated with biofuel are affected by the inorganic matter of the fuel. It is therefore expected that the lifetime of the oxygen carrier is limited, and preferably low‐cost oxygen carriers should be used. Oxygen carriers based on iron ore or steel manufacturing waste products are available in signi...

Tar management is one of the key components to achieve high energy efficiency and low operational costs connected to thermal gasification of biomass. Tars contain a significant amount of energy, and unconverted tars result in energy efficiency losses. Also, heavy tars can condense downstream processes, resulting in increased maintenance. Dual fluid...

Phosphorus (P) from biomass can cause operational problems in thermal conversion processes. In order to explore the release mechanism of P to the gas phase, carbothermic reduction of meta-, pyro-, and orthophosphates of ash elements commonly found in biomass; sodium, potassium, magnesium, and calcium was investigated. Mixtures of each phosphate and...

Steel converter slag, also called Linz-Donawitz (LD) slag, has been considered as an oxygen carrier for biofuel chemical looping applications due to its high availability. In addition to its content of iron which contributes to its oxygen-carrying capacity, LD slag also contains a significant amount of calcium. Calcium, however, is known to interac...

Chemical looping gasification (CLG) is an emerging process that aims to produce valuable chemical feedstocks. The key operational requirement of CLG is to limit the oxygen transfer from the air reactor (AR) to the fuel reactor (FR). This can be accomplished by partially oxidizing the oxygen carrier in the AR, which may lead to a higher reduction de...

Alkali is a problematic component in biomass and may create various operation issues in normal combustion as well as chemical looping combustion using biomass fuels (bio-CLC). To investigate the interaction of alkali with an oxygen carrier, a methodology has been developed where alkali salts are added with impregnated charcoal particles. This work...

Spinel ferrites (MxFe3-xO4) as oxygen carriers (OC) in chemical looping combustion (CLC) process have drawn significant interest owing to unique lattice structure and oxygen transfer properties. However, their employment in practice is likely cost prohibitive due to the complicated synthesis processes compared to natural occurring materials. In the...

Chemical-Looping Combustion (CLC) of biofuels is a promising technology for cost-efficient CO 2 separation and can lead to negative CO 2 emissions when combined with carbon capture and storage. A potential challenge in developing CLC technology is the effects of alkali metal-containing compounds released during fuel conversion. This study investiga...

The formation of NOx from fuel-bound nitrogen is important for the design of chemical-looping combustion (CLC) power plants. This work studied to what extent NO and NH3 reacts with the perovskite-like oxygen carrier ilmenite under conditions relevant to CLC. Based on mass balance calculations, N2 was the major outlet N-species in all experiments. M...

Manganese ores are promising oxygen carriers for chemical looping combustion (CLC), due to their high reactivity with combustible gases. In this work, a manganese ore called EB (Elwaleed B, originating from Egypt) is studied for its reaction rate with CH4, CO and H2 and the data are used in an analytically solved reactor model. The reactivity of fr...

Perovskites are well-known oxides for thermochemical energy storage applications (TCES) since they show a great potential for spontaneous O2 release due to their non-stoichiometry. Transition-metal-based perovskites are particularly promising candidates for TCES owing to their different oxidation states. It is important to test the thermal behavior...

Chemical looping combustion (CLC) is one of the most promising methods for carbon capture and storage (CCS). An oxygen carrier, i.e., a mineral that can be oxidized and reduced, is used to convert the fuel in the process. The produced CO2 is inherently separated from the air components that enables easier CCS. The use of biomass-based fuels is desi...

Oxygen carriers play an important role in chemical looping processes to transport oxygen for fuel conversion. In this study, the defluidization phenomena of oxygen carriers were examined under highly reducing conditions in a fluidized-bed batch reactor. This is highly relevant to chemical-looping gasification, where oxygen carriers could be reduced...

Alkali metal-containing compounds are readily released during thermal conversion of solid fuels, and may have both detrimental and beneficial effects on chemical looping combustion. Here, we characterize alkali interactions with the inner walls of a laboratory-scale reactor under oxidizing, reducing and inert conditions at temperatures up to 900 •...

A comparative study of CLC with paper, plastic, and coal as fuel was carried out. Experiments were carried out in a laboratory fluidized‐bed reactor by alternating between reduction and oxidation cycles. 0.1g of solid fuel was added to 20g of ilmenite (oxygen carrier). The result obtained showed that increasing temperature leads to an increase in t...

This study investigates vanadium extraction from steel converter slag from the LD (Linz-Donawitz) process. This slag has been used as an active bed material in a biomass boiler in a combustion technique called oxygen carrier aided combustion (OCAC). This usage in the boiler could be compared to the roasting step in the common roasting-leaching meth...

In this study, oxygen release/consumption behavior of calcium manganese-based oxides (CaMn1–xBxO3, where B: Cu, Fe, Mg and x = 0.1 or 0.2) used in a chemical looping oxygen uncoupling (CLOU) application was investigated. The effect of B-site dopants such as Fe, Mg, and Cu on the oxygen release behavior was also investigated with the aim to use thes...

Chemical Looping Gasification (CLG) is a dual fluidized bed gasification technique where an oxygen carrier is used as bed material instead of sand. An optimized process could have several advantages, including i) one concentrated CO2 stream, amiable for carbon capture, ii) less tar formation, iii) additional reaction pathways for syngas production,...

Thermochemical energy storage (TCES) is one of the most promising methods for utilization of solar energy. Metal oxides can exhibit reversible redox reactions that are useful for TCES applications. Especially, transitional metal oxides can undergo reduction reactions at high temperatures while absorbing energy given to the system. Later on, when th...

This study describes how potassium salts representative of those in bio ash affect the reactivity of the oxygen carrier ilmenite under moist and dry conditions. Ilmenite is a bench-mark oxygen carrier for chemical-looping combustion, a technique that can separate CO2 from flue gases with minimal energy penalty. Different potassium salts were mixed...

Chemical looping combustion (CLC) is a unique method which is developed for carbon capture and storage (CCS) to mitigate the climate change. In CLC, an oxygen carrier is used to convert the fuel and the produced CO2 is inherently separated from the air components which makes it suitable for CCS. CLC of biomass is a way to generate negative CO2 emis...

Facing increasingly severe environmental problems and substantial energy demand, chemical-looping with oxygen uncoupling (CLOU) is regarded as a highly promising technique to facilitate the application of carbon capture storage and utilization (CCS & U) due to its inherent gas separation. Thus, feasible oxygen carriers for continuous operation on t...

Carbon capture and storage (CCS) has been proposed as a bridging technology between the current energy production and a future renewable energy system. One promising carbon capture technology is chemical-looping combustion (CLC). In CLC the reactors are filled with metal oxide bed material called oxygen carriers. The interaction between oxygen carr...

As CO2 emission is one of the most critical issues which causes global warming, methods have been developed for carbon capture and storage. Chemical looping combustion (CLC) and chemical looping oxygen uncoupling (CLOU) are unique and useful methods for direct separation of carbon dioxide in combustion. In CLC and CLOU, metal oxides are used as an...

Chemical-Looping Combustion (CLC) is a combustion technology in which a solid oxygen carrier is used to convert fuel. The oxygen carrier is oxidized in air and subsequently transferred to a separate reactor in which it reacts with the fuel. The produced CO2 is inherently separate from the air components, making CLC an promising technology for Carbo...

Combined manganese-silicon oxides are promising candidates for thermochemical energy storage (TCES) since they show a great potential for spontaneous O2 release as utilized in chemical-looping with oxygen uncoupling (CLOU). For both concepts, as well as mechanical strength, cyclic stability of oxidation and reduction are very important. The high re...

Steel converter slag or LD slag is a byproduct of the basic oxygen steel production process, where raw iron from the blast furnace is converted to steel. LD slag contains mainly calcium and iron compounds and smaller amounts of magnesium, silicon, manganese and vanadium. The iron content, about 17 wt.% of the slag, makes this material a potential o...

Manganese ores have been identified as promising oxygen carriers for chemical-looping processes with solid fuels, including combustion and gasification systems. Such Mn-based minerals are readily available globally and could thus be a cheap alternative to other naturally occurring oxygen carriers, such as ilmenite. These ores are usually highly het...

Carbon capture and storage (CCS) has been acknowledged as an important strategy for mitigation of climate change. Although highly applicable for fossil fuels, CCS with biomass could have the added advantage of resulting in negative emissions of carbon dioxide. One promising carbon capture technology is chemical-looping combustion (CLC). In CLC the...

Combustion of organic materials in fluidized bed combustion is generally performed using an over‐stoichiometric air‐to‐fuel ratio. Despite excess air in the system, due to non‐perfect mixing in the system between reactants, there will be sub stoichiometric combustion regions present in the fluidized bed. These areas with oxygen‐deficient combustion...

We report an experimental evaluation of NH3 oxidation over three types of oxygen carrier materials under conditions relevant for chemical-looping combustion. The active metal and the oxidation state of the oxygen carrier is crucial to NO formation from NH3. Although, the carriers tested were equally efficient in terms of CO oxidation they differed...

The chemical-looping combustion (CLC) and chemical-looping oxygen uncoupling (CLOU) processes are unique and efficient methods for direct separation of carbon dioxide in combustion. In these processes, metal oxides are used under reducing atmosphere as an oxygen carrier to transfer oxygen between an air and a fuel reactor. The fuel is converted by...

The use of manganese ore as oxygen carrier has recently gained interest, primarily due to the combination of low cost and moderate to high reactivity. The possibility of an oxygen uncoupling reaction enhancing reactivity may be an additional advantage. In this paper, six manganese ores (Gloria, Tshipi, Gui Zhou, Metmin, Sibelco Calcined and SinAus)...

A small laboratory fluidized bed reactor is used to test the chemical reactivity of solid particles fluidized with a gas. The novelty of the system is that it can be used for testing any solid particles, and, in this work, oxygen carriers with Mn/Si oxide supported on TiO2 are used to present the possibilities and layout of the laboratory system. T...

Manganese‐iron oxide particles are a promising candidate for both chemical‐looping combustion (CLC) and thermochemical energy storage. In CLC, the ability of metal oxides to oxidize fuels in an oxygen‐free atmosphere and re‐oxidize in air is addressed. Whereas, reaction enthalpy is the main focus of thermochemical energy storage for, e.g. concentra...

In chemical-looping combustion (CLC), an oxygen carrier provides lattice oxygen for complete combustion of a fuel for heat and power production. The reduced metal oxide is then oxidized in a separate reactor. The combustion products CO2 and H2O are obtained in pure form, without any nitrogen in the gas. As no gas separation work is needed, this cou...

Chemical Looping Reforming (CLR) has been proposed as a new technology for tar removal from hot raw gas derived from biomass gasification. In this two-reactor fluidized bed process at atmospheric pressure, the bed material is circulating between a reformer, in which the bed material is in contact with the raw synthesis gas, and a regenerator, in wh...

In Chemical-looping combustion (CLC) an oxygen carrier is circulating, and transporting oxygen, between an air and fuel reactor, thus separating the flue gas stream from the nitrogen in the air. Except for the oxygen carrier all parts of a CLC system are conventional fluidized bed technology. Here, four iron-based industrial residues, and the conve...

In a Circulating Fluidized Bed (CFB) boiler one of the basic functions of the bed materials is to transport heat between different parts of the boiler to decrease heat gradients and thereby smoothen the operation. A novel concept Oxygen Carrier Aided Combustion (OCAC) replaces some or all of the bed materials with an oxygen carrier, which is a meta...

Manganese-based oxygen carriers can be used in chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU). This paper expands on a previous investigation into manganese ores as oxygen carriers for CLC. The paper presents reactivity data for eight ores with widely different compositions. Most importantly, the ores contained...

Raw gas derived from low-temperature biomass gasification usually contains condensable hydrocarbons referred to as “tars” as well as other hydrocarbons such as ethylene and other olefins. Reforming of these compounds via Chemical Looping Reforming has been recently proposed. In this work Cu supported on four different Al2O3/SiO2-based porous suppor...

The structural properties of (Fe0.2Mn0.8)xOy as a function of temperature under differing oxidizing and reducing atmospheres have been investigated using Thermal Gravimetric Analysis and neutron powder diffraction techniques. The principal observation is a reversible transition between the (low temperature) bixbyite and (high temperature) cubic spi...

Combined oxides, primarily manganese based, have shown great potential as oxygen carriers, as they often have oxygen uncoupling properties at relevant temperatures. These oxygen carriers could be a good alternative to copper-based materials. But in order to scale up or model the chemical-looping with oxygen uncoupling (CLOU) process reliable oxygen...

Combined Cu–Fe and Mn–Ni oxygen carriers were investigated as bed materials for chemical-looping combustion. The aim was to identify material combinations which yield oxygen carriers with a high reactivity towards gaseous fuels, such as CO, H2 and CH4, as well as sufficient mechanical durability. For this purpose, 18 different oxygen carriers were...

The oxygen carrier CaMn0.9Mg0.1O3-δ was successfully tested in different chemical-looping units. High methane conversion and oxygen uncoupling properties have been found for this type of material. Most of the CaMn0.9Mg0.1O3-δ oxygen carrier particles tested so far have been produced using the spray-drying method. In this work, the focus has been on...

The use of naturally occurring ores as oxygen carriers in CLC processes is attractive because of their relative abundance and low cost. Unfortunately, they typically exhibit lower reactivity and lack the mechanical robustness required, when compared to synthetically produced carriers. Impregnation is a suitable method for enhancing both the reactiv...

Measurements and modelling of the oxidation of ammonia over copper oxide (CuO) under conditions relevant to chemical-looping combustion with oxygen uncoupling show that CuO fully converts NH3 into NO or N2 under most of these conditions. Our experiments demonstrate that considerable amounts of NO are formed when the oxygen carrier is fully oxidised...

Oxygen carriers based on oxides of Mn and Si in combination with Mg, Al, Ca and Ti (Mn0.63Si0.27X0.1, X = Ca(OH)2, TiO2, MgO, AlOOH) were examined for CLOU (chemical-looping with oxygen uncoupling), in terms of oxygen uncoupling ability and ability to convert both methane and syngas. The focus was on the optimization of the production process to yi...

The oxidation of ammonia to NOx and N2 was investigated under conditions that pertain to the fuel reactor during the chemical-lopping combustion of coal with ilmenite. The catalytic decomposition of NH3, the oxidation of NH3 over ilmenite, and the reduction of NO by reduced ilmenite and NH3 were studied experimentally. The catalytic decomposition o...

Biomass gasification gas contains condensable hydrocarbons usually referred to as “tars”. The use of chemical-looping reforming (CLR) has been proposed as a downstream technology for tar removal from the hot raw gasification gas. In this work two different ZrO2 support materials impregnated with La, Sr, Fe and mixtures thereof have been investigate...

Biomass gasification gas contains condensable hydrocarbons usually referred to as “tars”. The use of chemical-looping reforming (CLR) has been proposed as a downstream technology for tar removal. In this work, the tar removal capabilities and the regeneration properties of two particularly promising bed materials, CuO/MgAl2O4 and La0.8Sr0.2FeO3/γ-A...

The reactivity and attrition resistance of Mn–Fe oxygen carriers with addition of Al2O3 as support have been investigated. Spray-dried oxygen-carrier particles with Mn:Fe molar ratios of 80:20 and 33:67 were prepared using different amounts of Al2O3. Each material was calcined for 4 h at 950 °C, 1100 °C or 1200 °C. The oxygen carriers were studied...

Combined oxygen carriers of Mn, Fe, and Si were screened for the chemical-looping with oxygen uncoupling process with the aim of identifying materials with high reactivity and sufficient attrition resistance. Eleven oxygen carrier materials were produced by spray-drying and then calcined for 4 h at 1100 and 1200°C. The ability of the oxygen carrier...

Due to discrepancy in the standard enthalpy of formation, (Formula presented.) , of copper(II) aluminate (CuAl2O4) reported in thermodynamic databases, the calculated reaction enthalpy, ΔHr, of CuAl2O4 with reducing gases varies considerably. In this work, the standard enthalpy of formation, (Formula presented.) , of CuAl2O4 is reassessed using the...

The chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) processes are novel solutions for efficient combustion with inherent separation of carbon dioxide. In this work, oxygen carriers based on CuO supported by zirconates of SrZrO3 and CaZrO3 are investigated. The oxygen carriers were produced by mechanical homogeni...

Sulfur tolerance and rate of oxygen release of combined Mn–Si oxygen carriers for chemical-looping with oxygen uncoupling (CLOU) is investigated. The oxygen carriers were produced by spray-drying and calcined at 1150 °C. The resistance toward sulfur and the rates of oxygen release were evaluated in a laboratory-scale fluidized-bed reactor. It was f...

A new type of Mn-based oxygen carrier was prepared by impregnating manganese ore with copper nitrate solution. Cyclic reduction and oxidation reactivity of the materials was investigated in a fluidized-bed reactor. The potential use of these oxygen carriers for chemical looping combustion (CLC) was examined. The reactivity of the manganese ore can...

Cheap and environmental friendly Mn-Si oxygen carriers manufactured from Mn3O4 and SiO2 by spray-drying have been investigated with respect to properties for chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU). Fifteen oxygen carriers with SiO2 content varying from 2wt% to 75wt% were prepared and calcined at 1050°C...

The feasibility of utilizing a combined oxide (Mn0.75Fe0.25)2O3 as an oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) has been investigated. To increase the strength and attrition resistance of such particles, the oxygen carrier was prepared together with MgAl2O4, CeO2, ZrO2 and Y2O3–ZrO2 as supports. The oxygen-carrier particles...

Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the oxygen carrier material will be lowered preferring low cost and environmental sound materials. In this work apparent kinetics describing the conversion of a natural rock ilmenite fro...

Ilmenite is an iron titanium oxide, extensively studied as oxygen carrier in the context of Chemical-Looping Combustion (CLC) as written by Berguerand and Lyngfelt (2009) and Schwebel et al. (2012). When used as bed material in conventional circulating fluidized bed (CFB) combustion, ilmenite was found to lower the emissions of carbon monoxide (CO)...

The removal of condensable hydrocarbons or tars from raw gas derived from biomass gasification presents an obstacle in the widespread application of biomass gasification. Hot catalytic tar cleaning as a secondary tar removal strategy is discussed as a tar cleaning technology. This can be realized in a dual-fluidized-bed reactor system, in which a c...

Oxygen carrier materials were synthesized using five different types of manganese ores with addition of iron oxide (Fe2O3), and they were investigated for their reactivity and properties in chemical looping with oxygen uncoupling (CLOU). Two different Mn/Fe molar ratios (1:2 and 2:1) were examined. The samples were manufactured by using a lab-scale...

Chemical-looping with oxygen uncoupling (CLOU) is an innovative method to oxidize fuels with inherent CO2 sequestration, which utilizes a solid oxygen-carrier material to provide O2 for fuel combustion. In this study, a range of CuO-based oxygen-carrier particles have been manufactured and examined. Out of 24 samples prepared, 10 were examined in a...

This study concerns production of oxygen-carrier particles using six different manganese ores. The ores were made to react with Ca(OH)2 at elevated temperature, forming calcium manganite. The method utilized to manufacture particles was extrusion. Methane and syngas conversion and oxygen release of the samples in inert atmosphere were investigated....

The chemical-looping combustion (CLC) process is a novel solution for efficient combustion with direct capture of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor, where the fuel reacts with the solid oxygen carrier. In this work, six different manganese ores are investigated as ox...

Oxygen-carrier materials for chemical-looping with oxygen uncoupling (CLOU) must be capable of taking up and releasing gas-phase O2 at conditions relevant for generation of heat and power. In principle, the capability of a certain material to do so is determined by its thermodynamic properties. This paper provides an overview of the possibility to...

Perovskite-structured oxygen carriers of the type CaxMn1–yMyO3−δ (M = Mg, Ti) have been investigated for the CLOU process. The oxygen carrier particles were produced by spray-drying and were calcined at 1300 °C for 4 h. A batch fluidized-bed reactor was used to investigate the chemical-looping characteristics of the materials. The effect of calcium...

The most widely used bed material in the existing fluidized bed systems is silica sand. Upon burning fuels with high alkali content, such as biomass, in a bed of silica sand, alkali silicates are formed as molten glassy phase that easily stick and form agglomerates, defluidization of the reactor and unplanned operational stops. Several materials ha...

Oxygen carriers based on manganese oxides have recently shown great promise for use in chemicallooping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU). In this work, different manganese ores have been investigated for application in CLC and CLOU. The reactivity towards methane and synthesis gas (50% CO in H2) and the oxygen unco...

The increasing CO2 levels in the atmosphere require an immediate action in order to avoid irreversible climate changes. Chemical-looping combustion (CLC) is an innovative technology that provides an energy and cost-effective separation of CO2 for further capture and storage and thereby helps to mitigate the anthropogenic CO2 emissions from thermoch...

The chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) processes are novel solutions for efficient combustion with inherent separation of carbon dioxide. In this work, oxygen carriers based on CuO supported by zirconia (ZrO2) and stabilized by calcia (CaO), magnesia (MgO) and ceria (CeO2) are investigated. The oxyg...