Inert chemical looping conversion of biochar with iron ore as oxygen carrier: Products conversion kinetics and structural evolution

Hu, Qiang; Mao, Qiaoting; Ren, Xixi; Yang, Haiping; Chen, Hanping

doi:10.1016/j.biortech.2018.12.038

Cited by 19 publications

(6 citation statements)

References 45 publications

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“…During this stage, biomass particles and OCs shrink as a result of devolatilization and oxygen consumption, respectively. The chemical reaction model is also considered a suitable model for the gas–solid reaction. , For the solid–solid reaction, random nucleation and subsequent growth models are regarded as appropriate options. , The solid–solid reaction begins at the surface where biomass char interacts with the OCs. Biomass char is gasified to syngas, and a layer of residue is deposited on the solid products.…”

Section: Modelingmentioning

confidence: 99%

Review of Biomass Chemical Looping Gasification in China

et al. 2020

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Biomass chemical looping gasification (BCLG) is a novel and promising technology for syngas production, in which lattice oxygen in oxygen carriers (OCs) reacts with biomass. OCs can continuously supply oxygen for biomass gasification using a redox cycle between different reactors, and the reduced OC can serve as a good catalyst for biomass tar and char cracking, improving the gasification efficiency. The notable advantages of BCLG have attracted attention around the world, particularly in China. Chinese researchers have become the major drivers of the development of BCLG technologies. The experience gained from the experimental tests of BCLG in China is valuable for the further development of BCLG. In this review, we mainly focus on the biomass feedstock, the OC, the tar yield, the reactor, and the results of the BCLG tests in Chinese studies. On the basis of those findings, we summarize the criteria for biomass and the OCs in BCLG, and potential directions for reactor development are briefly discussed. In general, the mechanism of BCLG has been investigated in many studies, and the effects of the operating conditions are relatively well-understood. However, there are still few reports on BCLG units that have potential for industrial application. The controllable composition of syngas is worthy of further investigation, and this is required for downstream utilization. Additionally, as a result of the low pollutant emission, chemical looping gasification of solid wastes might be available in the future.

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Section: Modelingmentioning

confidence: 99%

Review of Biomass Chemical Looping Gasification in China

et al. 2020

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“…In a life‐cycle perspective, biomass is known to balance the CO 2 emissions which can significantly enhance the carbon capture capability of CLC by accounting the absorbed CO 2 in its growth stage . Recently, the utilization of the woody shaving biochar was characterized by Hu et al for the product conversion kinetics and structural evolution in an iron‐based CLC. Fe‐based chemical‐looping gasification was utilized by Hu et al to generate syngas from wheat‐straw.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO₂mitigation in chemical‐looping combustion

et al. 2020

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Summary Chemical‐looping combustion (CLC) provides a platform to generate energy streams while mitigating CO2 using iron oxide as a carrier of oxygen. Through the reduction process, iron oxide experiences phase transformation to ultimately produce metallic iron. To understand iron oxide reduction characteristics and optimally design the fuel reactor, kinetic and thermodynamic analyses were proposed, utilizing graphite. This study aims to evaluate the reduction behavior under the non‐isothermal process of various mixture ratios of hematite and graphite via thermogravimetric analysis with simultaneously evaluating evolved gases using a Fourier transform infrared spectrometer. The Coats‐Redfern model was employed to approximate the kinetic and thermodynamic parameters which assessed the different reaction mechanisms together with the distributed activation energy model (DAEM). The results revealed that the hematite‐to‐graphite ratio of 4:1 had the highest reduction degree and had three distinct peaks representing three iron oxide reduction phases. The zero‐order reaction mechanism agreed with the experimental results compared with other reaction models. The thermodynamic analysis showed an overall endothermic spontaneous reaction for the three phases which signified the direct reduction of the iron oxides. The DAEM result validated a stepwise reduction of iron oxides to metallic iron. The study aids the optimal design of the CLC fuel reactor for enhanced system performance.

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“…Kinetic studies are essential for guiding reactor design . Most studies have been based on the thermogravimetric analyzer (TGA) for macroscopic kinetic analysis. − The kinetics of the existing biomass CLG are relatively rare. Huang et al − found that all reactions can be carried out at temperatures of >923 K (650 °C) in the biomass CLG.…”

Section: Introductionmentioning

confidence: 99%

Chemical Looping with Oxygen Uncoupling of the Lignocellulosic Biomass Main Model Compound: Product Distribution and Kinetic Analysis on Lignin

Zhang

et al. 2020

Energy Fuels

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Product distribution and kinetic analysis of lignin were investigated during the chemical looping with oxygen uncoupling (CLOU) process. Thermodynamic simulation of the CLOU process was performed on the basis of the Gibbs free energy minimization method. The influence of the reaction temperature and mixing ratio of the oxygen carrier (CuO) on the product distribution was explored via a fixed-bed reactor combined with online mass spectrometry. Kinetic parameters from the formation of the main gas-phase products were solved by an isoconversion method. The results of the thermodynamic analysis showed that the optimal reaction conditions were 850 °C and the blending ratio of the oxygen carrier was 1.22. Overall, nearly 50% of the solid product was obtained, and the gas products from CLOU were mainly CO and CO2, accounting for more than 90%. When the temperature was raised from 700 to 850 °C, the CO2 content was reduced from 66.65 to 55.66% and the CO content was increased from 30.02 to 40.40%. The product distribution was similar to the thermodynamic simulation results. Among the gaseous products, the activation energy of H2 formation was the highest, which can reach 88.14 kJ mol–1. This study provides basic data for the thermochemical conversion of lignin and other papermaking wastes.

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Inert chemical looping conversion of biochar with iron ore as oxygen carrier: Products conversion kinetics and structural evolution

Cited by 19 publications

References 45 publications

Review of Biomass Chemical Looping Gasification in China

Review of Biomass Chemical Looping Gasification in China

Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO₂mitigation in chemical‐looping combustion

Chemical Looping with Oxygen Uncoupling of the Lignocellulosic Biomass Main Model Compound: Product Distribution and Kinetic Analysis on Lignin

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Inert chemical looping conversion of biochar with iron ore as oxygen carrier: Products conversion kinetics and structural evolution

Cited by 19 publications

References 45 publications

Review of Biomass Chemical Looping Gasification in China

Review of Biomass Chemical Looping Gasification in China

Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO2mitigation in chemical‐looping combustion

Chemical Looping with Oxygen Uncoupling of the Lignocellulosic Biomass Main Model Compound: Product Distribution and Kinetic Analysis on Lignin

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Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO₂mitigation in chemical‐looping combustion