| 1. |
- Azimi, Golnar, 1985, et al.
(författare)
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Mn–Fe Oxides with Support of MgAl2O4, CeO2, ZrO2 and Y2O3–ZrO2 for Chemical-Looping Combustion and Chemical-Looping with Oxygen Uncoupling
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:25, s. 10358-10365
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of utilizing a combined oxide (Mn0.75Fe0.25)(2)O-3 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 were prepared using spray-drying. Each material was calcined for 4 h at 950, 1100 or 1200 degrees C. The materials were studied in a batch fluidized bed reactor to investigate their oxygen release and uptake potential and also their reactivity with CH4 and syngas. To gauge the mechanical stability of the different materials, the attrition resistance was measured in a jet-cup apparatus. With the exception of the material with MgAl2O4, the oxygen uncoupling property of the active combined oxides was largely kept intact using the added support materials. On the basis of the results from the reactivity tests and the measured attrition rates for all the particles, the material utilizing ZrO2 support seems to be the most promising candidate as an oxygen carrier for gaseous and solid fuels. However, due to phase transformations of the ZrO2 at higher temperatures, the calcination and operational temperature should likely not exceed 950 degrees C.
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| 2. |
- Hallberg, Peter, 1984, et al.
(författare)
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Experimental investigation of CaMnO3-δ based oxygen carriers used in continuous Chemical-Looping Combustion
- 2014
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Ingår i: International Journal of Chemical Engineering. - : Hindawi Limited. - 1687-806X .- 1687-8078. ; 2014:412517
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Tidskriftsartikel (refereegranskat)abstract
- Three materials of perovskite structure, (M = Mg or Mg and Ti), have been examined as oxygen carriers in continuous operation of chemical-looping combustion (CLC) in a circulating fluidized bed system with the designed fuel power 300 W. Natural gas was used as fuel. All three materials were capable of completely converting the fuel to carbon dioxide and water at 900°C. All materials also showed the ability to release gas phase oxygen when fluidized by inert gas at elevated temperature (700–950°C); that is, they were suitable for chemical looping with oxygen uncoupling (CLOU). Both fuel conversion and oxygen release improved with temperature. All three materials also showed good mechanical integrity, as the fraction of fines collected during experiments was small. These results indicate that the materials are promising oxygen carriers for chemical-looping combustion.
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| 3. |
- Jerndal, Erik, 1980, et al.
(författare)
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Investigation of NiO/NiAl2O4 Oxygen Carriers for Chemical-Looping Combustion Produced by Spray-Drying
- 2010
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 4:1, s. 23-35
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-looping combustion is a novel combustion technology with inherent separation of the greenhouse gas CO2. The technology uses circulating oxygen carriers to transfer oxygen from the combustion air to the fuel. In this paper, oxygen carriers based on commercially available NiO and α-Al2O3 were prepared using the industrial spray-drying method, and compared with particles prepared by freeze-granulation. The materials were investigated under alternating oxidizing and reducing conditions in a laboratory fluidized bed, thus simulating the cyclic conditions of a chemical-looping combustion system. The particles produced by spray-drying displayed a remarkable similarity to the freeze-granulated oxygen carriers, with high reactivity when the bed was fluidized and similar physical properties when sintered at the same temperature. This is an important result as it shows that the scaling-up from a laboratory production method, i.e. freeze-granulation, to a commercial method suitable for large-scale production, i.e. spray-drying, did not involve any unexpected difficulties. A difference noticed between the spray-dried and freeze-granulated particles was the sphericity. Whereas the freeze-granulated particles showed near perfect sphericity, a large portion of the spray-dried particles had hollow interiors. Defluidization was most likely to occur for highly reduced particles, at low gas velocities. The apparent density and crushing strength of the oxygen carriers could be increased either by increasing the sintering temperature or by increasing the sintering time. However, the fuel conversion was fairly unchanged when the sintering temperature was increased but was clearly improved when the sintering time was increased.
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| 4. |
- Jing, Dazheng, 1986, et al.
(författare)
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Effect of Production Parameters on the Spray-Dried Calcium Manganite Oxygen Carriers for Chemical-Looping Combustion
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:4, s. 3257-3268
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen carrier CaMn0.9Mg0.1O3-delta 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 CaMn(0.9)Mg(0.1)O(3-delta)oxygen carrier particles tested so far have been produced' using the spray-drying method. In this work, the focus has been on studying the effects of production parameters on the properties of this important oxygen carrier. The effects of three production parameters, i.e., milling time, calcination temperature, and calcination time, were examined for the spray-dried particles. The time of ball milling for the slurry prepared for spray-drying was varied from 5 to 45 min, the calcination temperature from 1300 to 1350 degrees C, and the calcination time from 4 to 16 h. None of these parameters had any influence on the final crystalline phases of the oxygen carrier, yet some of the properties were clearly changed. The bulk density, crushing strength, and resistance against physical attrition can be enhanced by increasing the calcination temperature, calcination time, or milling time. Further, the BET specific surface area and porosity of the oxygen carrier particles decreased when the slurry was milled or particles were calcined for extended periods. The average methane conversion of the oxygen carrier varied in a wide range, from 99% to 55% at 950 degrees C, depending upon the production parameters used. However, no obvious influence of the examined production parameters was observed for the oxygen uncoupling property of the oxygen carrier, which may be due to the thermodynamic limitation during testing.
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| 5. |
- Jing, Dazheng, 1986, et al.
(författare)
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Examination of oxygen uncoupling behaviour and reactivity towards methane for manganese silicate oxygen carriers in chemical-looping combustion
- 2014
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 29, s. 70-81
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Tidskriftsartikel (refereegranskat)abstract
- 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 and 1150°C. The ability of material to release O2 and their reactivity towards CH4 were examined in the temperature range 900-1100°C. Particles with a SiO2 content of more than 45wt% and calcined at 1150°C showed limited CLOU behaviour and poor reactivity towards CH4 at all temperatures investigated. The rest of the materials had significant CLOU properties and provided high conversion of CH4 under the experimental conditions chosen. Increasing the temperature of operation enhanced the CLOU behaviour and reactivity towards CH4. At temperatures above 950°C, the CH4 conversion was 90-100% for these materials. Crystalline phases identified by XRD in the oxidized samples with more than 45wt% SiO2 and calcined at 1150°C were mainly rhodonite MnSiO3. For materials with SiO2 content below 45wt%, braunite Mn7SiO12 was detected as the main phase in most of the samples after oxidation. This indicates that braunite Mn7SiO12 is the main active phase for oxygen transfer in CLC and CLOU, which is supported by thermodynamic calculations. The reactivity of all of the materials were also studied with syngas (50% CO and 50% H2), showing complete gas conversion at 950°C, except for materials with a SiO2 content of more than 45wt% and calcined at 1150°C. The mechanical integrity and attrition resistance of the oxygen carriers were examined in a jet-cup attrition rig, and although the attrition rates varied, some reactive material showed low rates of attrition, making them very promising oxygen carrier materials for applications related to CLC and CLOU. However, measures should probably be taken to improve the crushing strength to some extent. © 2014 Elsevier Ltd.
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| 6. |
- Jing, Dazheng, 1986, et al.
(författare)
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Innovative Oxygen Carrier Materials for Chemical-Looping Combustion
- 2013
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 37:2013, s. 645-653
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Konferensbidrag (refereegranskat)abstract
- In chemical-looping combustion, the oxygen needed for combustion of fuel is provided by metal oxides called oxygen carriers, and inherent separation of CO2 is achieved without energy penalty. For gaseous fuels, such as natural gas, Ni-based oxygen carriers have generally been shown to be the most reactive. But as Ni-based materials are burdened by high costs and environmental risks with respect to toxicity, it is of high importance to find viable non-Ni alternatives. In the EU-financed project INNOCUOUS, one of the key issues is to find novel non-Ni based oxygen carriers. In this paper results from reactivity investigations of three groups of oxygen carrier materials are reported. The materials were prepared by spray-drying, and are based on 1) CuO, 2) Ca-Mn-X-O where X = Cu, Fe, Ti and Mg, and 3) Mg-Mn-O. A number of materials showed a combination of sufficient mechanical strength, high release of gas phase oxygen and high reactivity with methane, and can thus be considered viable alternatives to Ni-based materials.
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| 7. |
- Mattisson, Tobias, 1970, et al.
(författare)
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Innovative oxygen carriers uplifting chemical-looping combustion,Chemical-looping combustion, natural gas, integrated project, oxygen carrier development
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 63, s. 113-130
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Konferensbidrag (refereegranskat)abstract
- This paper reports on the main results of the EU-financed project INNOCUOUS (Innovative Oxygen Carriers Uplifting Chemical-Looping Combustion). The project follows a series of successful projects with the aim of developing chemical-looping combustion (CLC) with gaseous fuels rich in methane. The project has included a wide range of experimental and modelling tasks, which included i) extensive screening of spray-dried and impregnated oxygen carriers, ii) production of impregnated and spray-dried oxygen carriers at >100 kg scale, iii) operation of several oxygen carriers at industrial conditions up to 120 kW scale and iv) techno-economic study of the next-scale CLC. One area of focus in the project has been the search for viable oxygen carriers which have low or no Ni. A large portfolio of interesting metal oxide systems has been found. Two oxygen carriers of CaMnxTiyMg1-x-yO3 were successfully produced in larger amounts by spray-drying and an oxygen carrier of Fe2O3/Al2O3 was produced in similar quantity using impregnation. The Ca-based material showed excellent behavior in a 10 kW and 120 kW unit, where complete combustion was achieved. With respect to the aim of replacing the bench-mark Ni-based material the project was thus very successful, as complete combustion has never been achieved in these units using Ni-based material.
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| 8. |
- Mattisson, Tobias, 1970, et al.
(författare)
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Testing of innovative Fe- and Ca-Mn-based oxygen carriers with natural gas in continuous operation
- 2017
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Ingår i: 9th Trondheim Conference on CO2 Capture, Transport and Storage, Trondheim, Norway, June 12-14, 2017.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chemical-looping combustion (CLC) of gaseous fuels, such as natural or refinery gas, could be a viable option in a variety of industries for production of heat and electricity with CCS. Further, CLC can be combined with conventional steam–methane reforming for efficientcarbon-neutral hydrogen production. A series of collaborate European projects have been carried out since 2002, which focused on oxygen-carrier development and upscaling of both the CLC process and oxygen-carrier production with natural gas and refinery gas as fuel. Inthe latest project, SUCCESS (2013-2017), a series of oxygen carriers based on Fe and Ca-Mn materials were developed using commercial and low-cost raw materials. Two commercial methods for particle production were used: impregnation of Fe2O3 on Al2O3 and spray-drying of CaMnO3. In this paper, selected results are presented from investigation of these two promising oxygen carriers using a laboratory-scale unit with continuous operation and a nominal fuel input of 10 kWth. In this unit, the gas velocities in the riser and in the grid jet zone of the gas distributor come close to gas velocities of industrial-scale units and the material is exposed to a large number of redox cycles. Therefore, this unit is highly applicable for judging particle lifetime. Both materials functioned well during operation with natural gas, with little or no agglomeration. The total time with fuel was 30 h and >100 h for the impregnated Fe-based material and the Ca-Mn-based material, respectively. Although the degree of elutriation was high for both materials, the actual fines production (
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| 9. |
- Moldenhauer, Patrick, 1983, et al.
(författare)
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Oxygen carrier development of calcium manganite-based materials with perovskite structure for chemical looping combustion of methane
- 2017
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Ingår i: Proceedings of the 42nd International Technical Conference on Clean Energy, Clearwater, FL, USA, June 11-15, 2017. ; , s. 12-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chemical-looping combustion (CLC) of gaseous fuels could be of interest in industrial processes for heat, power or hydrogen production with carbon capture. For instance, production of steam or hydrogen from refinery gas are possible applications. A series of collaborate European projects has been carried out since 2002, which focused on oxygen-carrier development and upscaling of both theCLC process and oxygen-carrier production with methane or natural gas as fuel. Most recently, in the FP7 SUCCESS project (2013-2017), Ca-Mn-based materials with perovskite structure, CaMnO3, were produced at a larger scale and with cheap and commercial raw materials. The main advantage with this type of oxygen carrier is the ability to release oxygen to the gas phase, hence promoting reactivity in the fuel reactor. In the project, a significant number of such materials were produced and tested. It was found that a perovskite structure can be obtained relatively easy with widely different raw materials for Ca, Mn, Ti and Mg. The produced materials generally had high reactivities and high attrition resistances, but were prone to sulfur poisoning.In this paper, selected results are presented from the different stages of material development and upscaling, i.e., from bench-scale reactors with batch and continuous operation, respectively, as well as from a laboratory-scale unit with continuous operation and a nominal fuel input of 10 kWth. In the 10 kW unit, the gas velocities in the riser and in the grid jet zone of the gas distributor come close to gas velocities of industrial-scale units and, therefore, this unit is used to assess particle lifetime. Results from the 10 kW unit show that very high degrees of fuel conversion can be reached while achieving very high lifetimes.
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| 10. |
- Moldenhauer, Patrick, 1983, et al.
(författare)
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Oxygen-Carrier Development of Calcium Manganite–Based Materials with Perovskite Structure for Chemical-Looping Combustion of Methane
- 2020
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Ingår i: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 8:6
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Tidskriftsartikel (refereegranskat)abstract
- The present work is related to the upscaling of calcium manganite–based oxygen-carrier materials, which have a perovskite structure, both with respect to the use of inexpensive raw materials, i.e., instead of pure chemicals, and the upscaling of production to multitonne batches. Results are presented from the two different stages of material development, i.e., raw material selection and upscaling. The evaluation involves both operation in chemical-looping combustor units of 300 W and 10 kW, and material characterization. In the latter unit, the gas velocities in the riser and in the grid-jet zone of the gas distributor come close to gas velocities of industrial-scale units and, therefore, this unit is also used to assess particle lifetime. Results from the various chemical-looping combustion units and oxygen-carrier materials produced from various raw materials of both high and low purity show that very high degrees of fuel conversion can be reached while achieving very high oxygen-carrier lifetimes. The composition of the oxygen-carrier materials seems robust and flexible with respect to the precursors used in its manufacturing.
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