The Experts below are selected from a list of 20939529 Experts worldwide ranked by ideXlab platform
Zhen Huang - One of the best experts on this subject based on the ideXlab platform.
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in situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier
Energy, 2020Co-Authors: Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhen Huang, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.
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biomass chemical looping gasification coupled with water co2 splitting using NiFe2O4 as an oxygen carrier
Energy Conversion and Management, 2019Co-Authors: Zhen Huang, Guoqiang Wei, Kun Zhao, Guixia Wang, Xiangfei Kong, Yanyan Feng, Haijun Tan, Shili Hou, Guangbin Jiang, Yanjun GuoAbstract:Abstract Bio-syngas generation with flexible H2 to CO ratios via biomass chemical-looping gasification (CLG) coupled with water/CO2-splitting using NiFe2O4 as an oxygen carrier (OC) was proposed in the present work. The presence of NiFe2O4 OC promotes biomass conversion, especially bio-char conversion at elevated temperature stage. Addition steam and/or CO2 into the carrying gas increased the weight loss rates of biomass. Up to 5.88 wt%/min and 4.97 wt%/min of the maximum weight loss rates were achieved during biomass conversion with NiFe2O4 OC in CO2 and steam flows in a TGA reactor, respectively. With NiFe2O4 as an oxygen carrier, an optimal lattice oxygen/biomass mass ratio is 0.51 giving the highest syngas yield of 0.77 m3/kgbiomass in the absence of steam or CO2 at 850 °C. Steam/biomass mass ratio of 2.25 gave the maximum carbon conversion of 92.53% and syngas yield of 1.38 m3/kgbiomass suggesting that steam addition significantly improves the biomass conversion and the syngas yield. Introducing a fraction of CO2 into steam could reduce the steam consumption as well as enhance the carbon conversion in biomass gasification step. NiFe2O4 OC serves as an effective catalyst for tars cracking in biomass-CLG. The tars content in the syngas generated in biomass-CLG with NiFe2O4 is 2.83 g/m3, which is much lower than that (14.25 g/m3) in biomass gasification with inert ZrO2. The productivities of H2 and CO are 211 ml/gOC and 101 ml/gOC in water- and CO2-splitting steps. The proposed approach can potentially be applied for providing bio-syngas with flexible H2 to CO ratios from 1:1 to 2.2:1 for purpose of various synthesis processes such as Fischer-Tropsch, acetic acid, and oxo-synthesis.
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reactivity investigation on chemical looping gasification of biomass char using nickel ferrite oxygen carrier
International Journal of Hydrogen Energy, 2017Co-Authors: Zhen Huang, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Chemical looping gasification (CLG) involves the use of an oxygen carrier (OC) which transfers oxygen from air to solid fuel to convert the fuel into synthesis gas, and the traditional gasifying agents such as oxygen-enriched air or high temperature steam are avoided. In order to improve the reactivity of OC with biomass char, facilitating biomass high-efficiency conversion, a compound Fe/Ni bimetallic oxide (NiFe2O4) was used as an OC in the present work. Effect of OC content and oxygen sources on char gasification were firstly investigated through a TG reactor. When the OC content in mixture sample attains 65 wt.%, the sample shows the maximum weight loss rate at relatively low temperature, indicating that it is very favorable for the redox reactions between OC and biomass char. The NiFe2O4 OC exhibits a good performance for char gasification, which is obvious higher than that of individual Fe2O3 OC and mechanically mixed Fe2O3 + NiO OC due to the Fe/Ni synergistic effect in unique spinel structure. According to the TGA experimental results, effect of the steam content and cyclic numbers on char gasification were investigated in a fixed bed reactor. Either too low steam content or too high steam content doesn't facilitate the char gasification. And suitable steam content of 56.33% is determined with maximum carbon conversion of 88.12% and synthesis gas yield of 2.58 L/g char. The reactivity of NiFe2O4 OC particles shows a downtrend within 20 cycles (∼64 h) due to the formation of Fe2O3 phase, which is derived from the iron element divorced from the Fe/Ni spinel structure. Secondly, the sintering of OC particles and ash deposit on the surface are also the reasons for the deactivation of NiFe2O4 OC. However, the carbon conversion and synthesis gas yield at the 20th cycle are still higher than those of the blank experiment. It indicates that the reactivity of NiFe2O4 OC can be maintained at a relatively long time and NiFe2O4 material can be used as a good OC candidate for char gasification in the long time running.
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screening of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production
Energy & Fuels, 2016Co-Authors: Shuai Liu, Yipeng Feng, Anqing Zheng, Zhen Huang, Yang Shen, Peter GlarborgAbstract:The objective of this paper is to systematically investigate the influences of different preparation methods on the properties of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production (CLH). The solid state (SS), coprecipitation (CP), hydrothermal (HT), and sol–gel (SG) methods were used to prepare NiFe2O4 oxygen carriers. Samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurement, as well as Barrett–Joyner–Halenda (BJH) porosity test. The performance of the prepared materials was first evaluated in a TGA reactor through a CO reduction and subsequent steam oxidation process. Then a complete redox process was conducted in a fixed-bed reactor, where the NiFe2O4 oxygen carrier was first reduced by simulated biomass pyrolysis gas (24% H2 + 24% CO + 12% CO2 + N2 balance), then reacted with steam to produce H2, and finally fully oxidized by a...
Zengli Zhao - One of the best experts on this subject based on the ideXlab platform.
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in situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier
Energy, 2020Co-Authors: Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhen Huang, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.
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reactivity investigation on chemical looping gasification of biomass char using nickel ferrite oxygen carrier
International Journal of Hydrogen Energy, 2017Co-Authors: Zhen Huang, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Chemical looping gasification (CLG) involves the use of an oxygen carrier (OC) which transfers oxygen from air to solid fuel to convert the fuel into synthesis gas, and the traditional gasifying agents such as oxygen-enriched air or high temperature steam are avoided. In order to improve the reactivity of OC with biomass char, facilitating biomass high-efficiency conversion, a compound Fe/Ni bimetallic oxide (NiFe2O4) was used as an OC in the present work. Effect of OC content and oxygen sources on char gasification were firstly investigated through a TG reactor. When the OC content in mixture sample attains 65 wt.%, the sample shows the maximum weight loss rate at relatively low temperature, indicating that it is very favorable for the redox reactions between OC and biomass char. The NiFe2O4 OC exhibits a good performance for char gasification, which is obvious higher than that of individual Fe2O3 OC and mechanically mixed Fe2O3 + NiO OC due to the Fe/Ni synergistic effect in unique spinel structure. According to the TGA experimental results, effect of the steam content and cyclic numbers on char gasification were investigated in a fixed bed reactor. Either too low steam content or too high steam content doesn't facilitate the char gasification. And suitable steam content of 56.33% is determined with maximum carbon conversion of 88.12% and synthesis gas yield of 2.58 L/g char. The reactivity of NiFe2O4 OC particles shows a downtrend within 20 cycles (∼64 h) due to the formation of Fe2O3 phase, which is derived from the iron element divorced from the Fe/Ni spinel structure. Secondly, the sintering of OC particles and ash deposit on the surface are also the reasons for the deactivation of NiFe2O4 OC. However, the carbon conversion and synthesis gas yield at the 20th cycle are still higher than those of the blank experiment. It indicates that the reactivity of NiFe2O4 OC can be maintained at a relatively long time and NiFe2O4 material can be used as a good OC candidate for char gasification in the long time running.
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Evaluation of multi-cycle performance of chemical looping dry reforming using CO2 as an oxidant with Fe-Ni bimetallic oxides
Journal of Energy Chemistry, 2016Co-Authors: Huanqi Jiang, Yipeng Feng, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Zengli Zhao, Fang He, Kun Zhao, Haibin LiAbstract:Chemical looping dry reforming (CLDR) is an innovative technology for CO2 utilization using the chemical looping principle. The CLDR process consists of three stages, i.e. CH4 reduction, CO2 reforming, and air oxidation. Spinel nickel ferrite (NiFe2O4) was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated. X-ray diffraction (XRD) and Laser Raman spectroscopy showed that a pure spinel crystalline phase (NiFe2O4) was obtained by a parallel flow co-precipitating method. NiFe2O4 was reduced into Fe-Ni alloy and wustite (FexO) during the CH4 reduction process. Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state: a mixture of spinel Ni1-xFe2+xO4, Fe2+yO4 and metallic Ni. And CO was generated in parallel during this stage. Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle. The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni1+xFe2-xO4 and Fe2O3. Although the original state of oxygen carrier (NiFe2O4) was not fully regenerated and agglomeration was observed, a good recyclability was shown in 10 successive redox cycles.
Guoqiang Wei - One of the best experts on this subject based on the ideXlab platform.
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in situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier
Energy, 2020Co-Authors: Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhen Huang, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.
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biomass chemical looping gasification coupled with water co2 splitting using NiFe2O4 as an oxygen carrier
Energy Conversion and Management, 2019Co-Authors: Zhen Huang, Guoqiang Wei, Kun Zhao, Guixia Wang, Xiangfei Kong, Yanyan Feng, Haijun Tan, Shili Hou, Guangbin Jiang, Yanjun GuoAbstract:Abstract Bio-syngas generation with flexible H2 to CO ratios via biomass chemical-looping gasification (CLG) coupled with water/CO2-splitting using NiFe2O4 as an oxygen carrier (OC) was proposed in the present work. The presence of NiFe2O4 OC promotes biomass conversion, especially bio-char conversion at elevated temperature stage. Addition steam and/or CO2 into the carrying gas increased the weight loss rates of biomass. Up to 5.88 wt%/min and 4.97 wt%/min of the maximum weight loss rates were achieved during biomass conversion with NiFe2O4 OC in CO2 and steam flows in a TGA reactor, respectively. With NiFe2O4 as an oxygen carrier, an optimal lattice oxygen/biomass mass ratio is 0.51 giving the highest syngas yield of 0.77 m3/kgbiomass in the absence of steam or CO2 at 850 °C. Steam/biomass mass ratio of 2.25 gave the maximum carbon conversion of 92.53% and syngas yield of 1.38 m3/kgbiomass suggesting that steam addition significantly improves the biomass conversion and the syngas yield. Introducing a fraction of CO2 into steam could reduce the steam consumption as well as enhance the carbon conversion in biomass gasification step. NiFe2O4 OC serves as an effective catalyst for tars cracking in biomass-CLG. The tars content in the syngas generated in biomass-CLG with NiFe2O4 is 2.83 g/m3, which is much lower than that (14.25 g/m3) in biomass gasification with inert ZrO2. The productivities of H2 and CO are 211 ml/gOC and 101 ml/gOC in water- and CO2-splitting steps. The proposed approach can potentially be applied for providing bio-syngas with flexible H2 to CO ratios from 1:1 to 2.2:1 for purpose of various synthesis processes such as Fischer-Tropsch, acetic acid, and oxo-synthesis.
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reactivity investigation on chemical looping gasification of biomass char using nickel ferrite oxygen carrier
International Journal of Hydrogen Energy, 2017Co-Authors: Zhen Huang, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Chemical looping gasification (CLG) involves the use of an oxygen carrier (OC) which transfers oxygen from air to solid fuel to convert the fuel into synthesis gas, and the traditional gasifying agents such as oxygen-enriched air or high temperature steam are avoided. In order to improve the reactivity of OC with biomass char, facilitating biomass high-efficiency conversion, a compound Fe/Ni bimetallic oxide (NiFe2O4) was used as an OC in the present work. Effect of OC content and oxygen sources on char gasification were firstly investigated through a TG reactor. When the OC content in mixture sample attains 65 wt.%, the sample shows the maximum weight loss rate at relatively low temperature, indicating that it is very favorable for the redox reactions between OC and biomass char. The NiFe2O4 OC exhibits a good performance for char gasification, which is obvious higher than that of individual Fe2O3 OC and mechanically mixed Fe2O3 + NiO OC due to the Fe/Ni synergistic effect in unique spinel structure. According to the TGA experimental results, effect of the steam content and cyclic numbers on char gasification were investigated in a fixed bed reactor. Either too low steam content or too high steam content doesn't facilitate the char gasification. And suitable steam content of 56.33% is determined with maximum carbon conversion of 88.12% and synthesis gas yield of 2.58 L/g char. The reactivity of NiFe2O4 OC particles shows a downtrend within 20 cycles (∼64 h) due to the formation of Fe2O3 phase, which is derived from the iron element divorced from the Fe/Ni spinel structure. Secondly, the sintering of OC particles and ash deposit on the surface are also the reasons for the deactivation of NiFe2O4 OC. However, the carbon conversion and synthesis gas yield at the 20th cycle are still higher than those of the blank experiment. It indicates that the reactivity of NiFe2O4 OC can be maintained at a relatively long time and NiFe2O4 material can be used as a good OC candidate for char gasification in the long time running.
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Evaluation of multi-cycle performance of chemical looping dry reforming using CO2 as an oxidant with Fe-Ni bimetallic oxides
Journal of Energy Chemistry, 2016Co-Authors: Huanqi Jiang, Yipeng Feng, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Zengli Zhao, Fang He, Kun Zhao, Haibin LiAbstract:Chemical looping dry reforming (CLDR) is an innovative technology for CO2 utilization using the chemical looping principle. The CLDR process consists of three stages, i.e. CH4 reduction, CO2 reforming, and air oxidation. Spinel nickel ferrite (NiFe2O4) was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated. X-ray diffraction (XRD) and Laser Raman spectroscopy showed that a pure spinel crystalline phase (NiFe2O4) was obtained by a parallel flow co-precipitating method. NiFe2O4 was reduced into Fe-Ni alloy and wustite (FexO) during the CH4 reduction process. Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state: a mixture of spinel Ni1-xFe2+xO4, Fe2+yO4 and metallic Ni. And CO was generated in parallel during this stage. Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle. The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni1+xFe2-xO4 and Fe2O3. Although the original state of oxygen carrier (NiFe2O4) was not fully regenerated and agglomeration was observed, a good recyclability was shown in 10 successive redox cycles.
Kun Zhao - One of the best experts on this subject based on the ideXlab platform.
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in situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier
Energy, 2020Co-Authors: Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhen Huang, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.
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biomass chemical looping gasification coupled with water co2 splitting using NiFe2O4 as an oxygen carrier
Energy Conversion and Management, 2019Co-Authors: Zhen Huang, Guoqiang Wei, Kun Zhao, Guixia Wang, Xiangfei Kong, Yanyan Feng, Haijun Tan, Shili Hou, Guangbin Jiang, Yanjun GuoAbstract:Abstract Bio-syngas generation with flexible H2 to CO ratios via biomass chemical-looping gasification (CLG) coupled with water/CO2-splitting using NiFe2O4 as an oxygen carrier (OC) was proposed in the present work. The presence of NiFe2O4 OC promotes biomass conversion, especially bio-char conversion at elevated temperature stage. Addition steam and/or CO2 into the carrying gas increased the weight loss rates of biomass. Up to 5.88 wt%/min and 4.97 wt%/min of the maximum weight loss rates were achieved during biomass conversion with NiFe2O4 OC in CO2 and steam flows in a TGA reactor, respectively. With NiFe2O4 as an oxygen carrier, an optimal lattice oxygen/biomass mass ratio is 0.51 giving the highest syngas yield of 0.77 m3/kgbiomass in the absence of steam or CO2 at 850 °C. Steam/biomass mass ratio of 2.25 gave the maximum carbon conversion of 92.53% and syngas yield of 1.38 m3/kgbiomass suggesting that steam addition significantly improves the biomass conversion and the syngas yield. Introducing a fraction of CO2 into steam could reduce the steam consumption as well as enhance the carbon conversion in biomass gasification step. NiFe2O4 OC serves as an effective catalyst for tars cracking in biomass-CLG. The tars content in the syngas generated in biomass-CLG with NiFe2O4 is 2.83 g/m3, which is much lower than that (14.25 g/m3) in biomass gasification with inert ZrO2. The productivities of H2 and CO are 211 ml/gOC and 101 ml/gOC in water- and CO2-splitting steps. The proposed approach can potentially be applied for providing bio-syngas with flexible H2 to CO ratios from 1:1 to 2.2:1 for purpose of various synthesis processes such as Fischer-Tropsch, acetic acid, and oxo-synthesis.
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reactivity investigation on chemical looping gasification of biomass char using nickel ferrite oxygen carrier
International Journal of Hydrogen Energy, 2017Co-Authors: Zhen Huang, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Chemical looping gasification (CLG) involves the use of an oxygen carrier (OC) which transfers oxygen from air to solid fuel to convert the fuel into synthesis gas, and the traditional gasifying agents such as oxygen-enriched air or high temperature steam are avoided. In order to improve the reactivity of OC with biomass char, facilitating biomass high-efficiency conversion, a compound Fe/Ni bimetallic oxide (NiFe2O4) was used as an OC in the present work. Effect of OC content and oxygen sources on char gasification were firstly investigated through a TG reactor. When the OC content in mixture sample attains 65 wt.%, the sample shows the maximum weight loss rate at relatively low temperature, indicating that it is very favorable for the redox reactions between OC and biomass char. The NiFe2O4 OC exhibits a good performance for char gasification, which is obvious higher than that of individual Fe2O3 OC and mechanically mixed Fe2O3 + NiO OC due to the Fe/Ni synergistic effect in unique spinel structure. According to the TGA experimental results, effect of the steam content and cyclic numbers on char gasification were investigated in a fixed bed reactor. Either too low steam content or too high steam content doesn't facilitate the char gasification. And suitable steam content of 56.33% is determined with maximum carbon conversion of 88.12% and synthesis gas yield of 2.58 L/g char. The reactivity of NiFe2O4 OC particles shows a downtrend within 20 cycles (∼64 h) due to the formation of Fe2O3 phase, which is derived from the iron element divorced from the Fe/Ni spinel structure. Secondly, the sintering of OC particles and ash deposit on the surface are also the reasons for the deactivation of NiFe2O4 OC. However, the carbon conversion and synthesis gas yield at the 20th cycle are still higher than those of the blank experiment. It indicates that the reactivity of NiFe2O4 OC can be maintained at a relatively long time and NiFe2O4 material can be used as a good OC candidate for char gasification in the long time running.
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Evaluation of multi-cycle performance of chemical looping dry reforming using CO2 as an oxidant with Fe-Ni bimetallic oxides
Journal of Energy Chemistry, 2016Co-Authors: Huanqi Jiang, Yipeng Feng, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Zengli Zhao, Fang He, Kun Zhao, Haibin LiAbstract:Chemical looping dry reforming (CLDR) is an innovative technology for CO2 utilization using the chemical looping principle. The CLDR process consists of three stages, i.e. CH4 reduction, CO2 reforming, and air oxidation. Spinel nickel ferrite (NiFe2O4) was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated. X-ray diffraction (XRD) and Laser Raman spectroscopy showed that a pure spinel crystalline phase (NiFe2O4) was obtained by a parallel flow co-precipitating method. NiFe2O4 was reduced into Fe-Ni alloy and wustite (FexO) during the CH4 reduction process. Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state: a mixture of spinel Ni1-xFe2+xO4, Fe2+yO4 and metallic Ni. And CO was generated in parallel during this stage. Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle. The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni1+xFe2-xO4 and Fe2O3. Although the original state of oxygen carrier (NiFe2O4) was not fully regenerated and agglomeration was observed, a good recyclability was shown in 10 successive redox cycles.
Anqing Zheng - One of the best experts on this subject based on the ideXlab platform.
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in situ removal of toluene as a biomass tar model compound using NiFe2O4 for application in chemical looping gasification oxygen carrier
Energy, 2020Co-Authors: Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhen Huang, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Efficient removal of tar is a major challenge for biomass gasification. A scheme based on chemical looping gasification (CLG) provides a promising alternative for converting biomass into syngas with low tar content. The current study investigates the reactivity of NiFe2O4 oxygen carrier for toluene (biomass tar model compound) removal. The NiFe2O4 oxygen carrier shows a dual-function of oxidation-catalysis for toluene cracking and significantly promotes toluene cracked into carbon and H2. A suitable temperature for toluene cracking is determined at 850 °C. As the weight hourly space velocity (WHSV) increases by approximately a factor of nine, the toluene removal decreases slightly by 2.78%. The toluene removal does not significantly decrease with the crystal phase transformation of the oxygen carrier. Addition of steam significantly eliminates the carbon deposition, which decreases to 4.97% at S/C (steam/toluene) ratio of 1.20. The catalytic activity of NiFe2O4 initially remained stable for a long time, and then started showing a slight decrease after transitory activation during the long-term experiment (82 h). These results fully demonstrate that the NiFe2O4 is a good oxygen carrier for tar removal in biomass CLG.
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reactivity investigation on chemical looping gasification of biomass char using nickel ferrite oxygen carrier
International Journal of Hydrogen Energy, 2017Co-Authors: Zhen Huang, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Kun Zhao, Zhengbing Deng, Zengli ZhaoAbstract:Abstract Chemical looping gasification (CLG) involves the use of an oxygen carrier (OC) which transfers oxygen from air to solid fuel to convert the fuel into synthesis gas, and the traditional gasifying agents such as oxygen-enriched air or high temperature steam are avoided. In order to improve the reactivity of OC with biomass char, facilitating biomass high-efficiency conversion, a compound Fe/Ni bimetallic oxide (NiFe2O4) was used as an OC in the present work. Effect of OC content and oxygen sources on char gasification were firstly investigated through a TG reactor. When the OC content in mixture sample attains 65 wt.%, the sample shows the maximum weight loss rate at relatively low temperature, indicating that it is very favorable for the redox reactions between OC and biomass char. The NiFe2O4 OC exhibits a good performance for char gasification, which is obvious higher than that of individual Fe2O3 OC and mechanically mixed Fe2O3 + NiO OC due to the Fe/Ni synergistic effect in unique spinel structure. According to the TGA experimental results, effect of the steam content and cyclic numbers on char gasification were investigated in a fixed bed reactor. Either too low steam content or too high steam content doesn't facilitate the char gasification. And suitable steam content of 56.33% is determined with maximum carbon conversion of 88.12% and synthesis gas yield of 2.58 L/g char. The reactivity of NiFe2O4 OC particles shows a downtrend within 20 cycles (∼64 h) due to the formation of Fe2O3 phase, which is derived from the iron element divorced from the Fe/Ni spinel structure. Secondly, the sintering of OC particles and ash deposit on the surface are also the reasons for the deactivation of NiFe2O4 OC. However, the carbon conversion and synthesis gas yield at the 20th cycle are still higher than those of the blank experiment. It indicates that the reactivity of NiFe2O4 OC can be maintained at a relatively long time and NiFe2O4 material can be used as a good OC candidate for char gasification in the long time running.
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screening of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production
Energy & Fuels, 2016Co-Authors: Shuai Liu, Yipeng Feng, Anqing Zheng, Zhen Huang, Yang Shen, Peter GlarborgAbstract:The objective of this paper is to systematically investigate the influences of different preparation methods on the properties of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production (CLH). The solid state (SS), coprecipitation (CP), hydrothermal (HT), and sol–gel (SG) methods were used to prepare NiFe2O4 oxygen carriers. Samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area measurement, as well as Barrett–Joyner–Halenda (BJH) porosity test. The performance of the prepared materials was first evaluated in a TGA reactor through a CO reduction and subsequent steam oxidation process. Then a complete redox process was conducted in a fixed-bed reactor, where the NiFe2O4 oxygen carrier was first reduced by simulated biomass pyrolysis gas (24% H2 + 24% CO + 12% CO2 + N2 balance), then reacted with steam to produce H2, and finally fully oxidized by a...
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Evaluation of multi-cycle performance of chemical looping dry reforming using CO2 as an oxidant with Fe-Ni bimetallic oxides
Journal of Energy Chemistry, 2016Co-Authors: Huanqi Jiang, Yipeng Feng, Guoqiang Wei, Dezhen Chen, Anqing Zheng, Zengli Zhao, Fang He, Kun Zhao, Haibin LiAbstract:Chemical looping dry reforming (CLDR) is an innovative technology for CO2 utilization using the chemical looping principle. The CLDR process consists of three stages, i.e. CH4 reduction, CO2 reforming, and air oxidation. Spinel nickel ferrite (NiFe2O4) was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated. X-ray diffraction (XRD) and Laser Raman spectroscopy showed that a pure spinel crystalline phase (NiFe2O4) was obtained by a parallel flow co-precipitating method. NiFe2O4 was reduced into Fe-Ni alloy and wustite (FexO) during the CH4 reduction process. Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state: a mixture of spinel Ni1-xFe2+xO4, Fe2+yO4 and metallic Ni. And CO was generated in parallel during this stage. Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle. The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni1+xFe2-xO4 and Fe2O3. Although the original state of oxygen carrier (NiFe2O4) was not fully regenerated and agglomeration was observed, a good recyclability was shown in 10 successive redox cycles.
