Hydrogen-rich Syngas Production Research Articles

Hydrogen-rich syngas production by catalytic cracking of polypropylene over activated carbon based monometallic and bimetallic Fe/Ni catalysts

The aim of this study is to efficiently produce hydrogen-rich syngas. The thermal conversion experiment of polypropylene was carried out in a two-stage pyrolytic-catalytic device. Activated carbon based catalyst was developed, the catalytic performance of monomial and bimetallic catalysts was explored, and the influence of metal addition ratio in bimetallic catalysts on hydrogen production performance was analyzed. The microscopic morphology and structural characterization of the unreacted and spent catalyst were analyzed, and the effect of active substance in catalyst on the reaction performance was described. Under optimized reaction conditions, bimetallic catalyst 5Fe–10Ni had excellent catalytic activity, large hydrogen yield (136.32 mmol/gPP) and high carbon deposition quality. For this high performance catalyst, the catalyst stability was verified by 10 cycles of recycling experiments. The method of hydrogen production from waste plastic cracking in this paper will provide new ideas for high value utilization of plastic and hydrogen production.

Chemical Kinetic Modeling of Air-Steam Gasification of Eucalyptus Wood Sawdust for H2-Rich Syngas Production.

The aim of this research paper is to develop a chemical kinetic model, based on the mechanism of surface reactions, for air-steam gasification of eucalyptus wood sawdust (CH1.63O1.02) and analyze the hydrogen-rich syngas production. Experiments are performed on a bubbling fluidized-bed gasifier using air-steam as a gasifying agent. For validation of the developed kinetic model, the outcome of the model is compared with that of experimental data, which shows a root-mean-square error of less than 4. Different parameters such as equivalence ratios (0 ≤ ER ≤ 0.4), particle size (100 ≤ Dp ≤ 1000 μm), gasification temperature (900 ≤ T ≤ 1200 K), pressure (1 ≤ P ≤ 20 atm), and steam-to-biomass ratio (0 ≤ SBR ≤ 2) are considered for the analysis. The one-parameter-at-a-time concept is employed to maximize the production of H2-rich syngas. Results indicate that the maximum concentration of hydrogen is 55.04 vol % (experimental) and 51.81 vol % (predicted) at optimum conditions: ER = 0, Dp = 100 μm, T = 1100 K, P = 1 atm, and SBR = 0.75. Gasification performance parameters such as hydrogen gas yield, heating values, cold gas efficiency, etc., are evaluated.

ASPEN plus modelling of air-CO2 and air-steam-CO2 gasification of Parthenium hysterophorous for hydrogen and carbon monoxide rich syngas production

The simulation modelling of air-CO2 and air-steam-CO2 gasification of the aggressive weed, Parthenium hysterophorous is performed using an ASPEN Plus simulator and the outcomes are compared with an existing gasification study taken from the literature. The effect of temperature on the biomass gasification process, and the generation of the gases carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), and methane (CH4) are estimated in the temperature range of 300 – 1000 °C. The objectives of this study are to identify the important processes within the operating variables of elemental parameters with the gasifying agents (air-CO2 and air-steam-CO2) and to understand how temperature impacts the yield of syngas. Research findings from the gasification of biomass by air-CO2 and air-steam-CO2 are also used for comparison. The syngas yield appears to be significantly impacted by temperature variation. Due to the introduction of CO2, the studies of the gas evolution in this gasification process demonstrate a substantial increase in the output % of H2 and CO due to the introduction of CO2.

Hydrogen production from hazardous petroleum sludge gasification over nickel-loaded porous ZSM-5 and Al2O3 catalysts under air condition

In this study, the potential of petroleum sludge (PS) for hydrogen production via the gasification process was evaluated. For this purpose, nickel (Ni)-loaded ZSM-5 and γ-Al2O3 (Ni-ZS and Ni–Al) catalysts were prepared and employed for PS gasification in air condition. The effects of different supports, Ni loading content, and reaction temperatures on the production of hydrogen-rich syngas along with the stability and reusability of the best catalyst were investigated. Applying 5%Ni-ZS obtained more gas yield (68.09 wt%) and hydrogen selectivity (25.04 vol%) compared to those obtained by 5%Ni–Al mostly owing to weak metal-support interactions which led to the dominance of well-dispersed metallic Ni. At various Ni loading percentages, 10%Ni-ZS showed the highest catalytic efficiency, which increased both gas yield (70.92 wt%) and hydrogen selectivity (30.74 vol%). However, excessive Ni content (especially 20%) significantly reduced the gas yield and hydrogen selectivity because of limited accessibility of support's active sites, poor dispersion of Ni, and inappropriate acidity. Increasing the temperature promoted the gas yield and produced hydrogen, where the highest gas yield (73.18 wt%) and hydrogen selectivity (33.15 vol%) were obtained at 850 °C due to the endothermic nature of gasification reactions. The 10%Ni-ZS catalyst showed proper stability during three consecutive experiments at 850 °C. The spent catalyst was successfully regenerated without a significant reduction in activity or selectivity.

Hydrogen-rich syngas production from the lignocellulosic biomass by catalytic gasification: A state of art review on advance technologies, economic challenges, and future prospectus

Global population growth, modernization, and industrialization have all significantly increased energy consumption, which has worsened the climate and led to greenhouse gas emissions, forcing researchers to look into eco-friendly, renewable, and sustainable energy sources. Hydrogen (H2) is emerging as one of the cleanest and most carbon-free future energy carriers generated from diverse domestic resources, organic wastes, lignocellulosic biomass, natural gas, and fossil fuels by biochemical and thermochemical routes. Applying thermochemical routes, lignocellulosic biomass for sustainable H2 production have shown great potential for industrial implementation. As a result, the current study emphasizes the state-of-the-art review of developments in gasification technologies, operating circumstances, and catalysts employed for producing H2-rich syngas. Emerging catalytic technologies to improve H2-rich syngas production were discussed in detail. New technologies including, solar gasification, microwave gasification, plasma gasification, and integrated pyrolysis-gasification were also highlighted. Finally, the prospects and challenges of the process are also pointed out in brief to assist future researchers and stakeholders working for its commercialization.

Polypropylene pyrolysis and steam reforming over Fe-based catalyst supported on activated carbon for the production of hydrogen-rich syngas

The purpose of this study is to explore a method for the high-yield production of hydrogen by pyrolysis and steam reforming of polymer plastics. The developed Fe-based catalyst supported on activated carbon was applied to reactions with polypropylene for hydrogen production. The effects of iron loading (%) in the catalyst, the total catalyst amount, and the water content in the reaction atmosphere on the performance of hydrogen and gas production were investigated. Under the optimal conditions, the hydrogen yield without water added reached 38.73 mmol/gPP, and this yield was significantly improved by adding water into the reaction atmosphere. By optimizing the amount of water added, the hydrogen yield reached 112.71 mmol/gPP. The surface morphology and structural components of the fresh and used catalysts were characterized, and the morphology and quantity of carbon deposition on the catalyst were analysed. The catalytic stability of the 15Fe/AC catalyst was determined by repeating the test 10 times under the optimal reaction conditions. As the reaction time increased, the selectivity of the catalyst for hydrogen decreased and that for hydrocarbons increased. Moreover, the experimental method used in this study had excellent hydrogen production capacity. Thus, this study provided a novel method for the high-efficiency production of hydrogen by pyrolysis and steam reforming of polymer plastics.

Analysis of the behaviour of limestone sorbents for sorption-enhanced gasification in dual interconnected fluidised bed reactor

Sorption-Enhanced Gasification (SEG) is a promising technology based on the use of Ca-based sorbents (like limestone) to selectively remove CO2 from the gasification environment, for production of hydrogen rich syngas. This process benefits from the extensive understanding of “calcium looping”, a post-combustion technique aimed at removing CO2 from flue gas. Calcium looping is most typically carried out in Dual Interconnected Fluidised Bed (DIFB) reactors. The correct design of sorbent looping processes in DIFB reactors must consider: 1) sorbent deactivation (i.e., decay of CO2 capture performance) over repeated cycling; 2) the loss of sorbent material due to elutriation, that may be enhanced by attrition and fragmentation. The aim of this study is to investigate six different commercial limestones in terms of sorbent performance and attrition/fragmentation tendency under simulated SEG conditions.The experimental campaign was carried out in a lab-scale DIFB reactor, electrically heated. The six sorbents were limestones coming from different parts of Europe. A synthetic gas including air, CO2 and N2 was used to simulate SEG conditions. A “test” consisted of ten complete cycles of calcination/carbonation. Calcination was performed at 850 °C, fluidising the bed with a stream of 10 % CO2 (balance air) to simulate oxidising conditions typical of the combustor-calciner. In the carbonation stage, the temperature was kept at 650 °C and the CO2 concentration was set at 10 % (balance nitrogen) to account for reducing conditions typical of the gasifier-carbonator.During each carbonation stage, the CO2 concentration at the exhaust was continuously monitored to calculate the CO2 specific capture performance. The sorbent attrition rate was determined by working out the mass of fines elutriated at the exhaust and collected in filters, for each calcination and carbonation stage. After a test, each exhaust sorbent sample was sieve-analysed to obtain the particle size distribution and the fraction of generated fragments. Moreover, the characterisation was extended by carrying out, in an ex situ apparatus, impact fragmentation tests on samples preprocessed in DIFB.Results were critically analysed in the light of the adopted operating conditions, by also including: (a) a fitting equation of conversion data, able to give indications on the sorbent resistance to sintering; (b) a carbonation reaction model, that allowed the estimation of the decrease in the sorbent specific surface area as long as the number of cycles increases.

Oxidative catalytic steam gasification of sugarcane bagasse for hydrogen rich syngas production

Reactive Flash Volatilization (RFV) is an emerging thermochemical method to produce tar free hydrogen rich syngas from waste biomass at relatively lower temperature (<900 °C) in a single stage catalytic reactor within a millisecond residence time. Here, we show catalytic RFV of bagasse using Ru, Rh, Pd, or Re promoted Ni/Al2O3 catalysts under steam rich and oxygen deficient environment. The optimum reaction conditions were found to be 800 °C, steam to carbon ratio = 1.7 and carbon to oxygen ratio = 0.6. Rh–Ni/Al2O3 performed the best, resulting in highest hydrogen concentration in the synthesis gas at 54.8%, with a corresponding yield of 106.4 g-H2/kg bagasse. A carbon conversion efficiency of 99.96% was achieved using Rh–Ni, followed by Ru–Ni, Pd–Ni, Re–Ni and mono metallic Ni catalyst in that order. Alkali and Alkaline Earth Metal species present in the bagasse ash and char, that deposited on the catalyst, was found to enhance its activity and stability. The hydrogen yield from bagasse was higher than previously reported woody biomass and comparable to the microalgae.

Chemical looping gasification of biomass char for hydrogen-rich syngas production via Mn-doped Fe2O3 oxygen carrier

Because of its low cost, an iron-based oxygen carrier is a promising candidate for hydrogen-rich syngas production from the chemical looping gasification of biomass. However, it needs modification from a reactivity point of view. In this study effect of Mn doping on Fe2O3 has been investigated for hydrogen-rich syngas production from biomass char at different temperatures (700–900 °C) and steam flow rates (60–100 μL/min). Several techniques (XRD, XPS, BET, and TPR-H2) have been utilized to characterize fresh and spent oxygen carriers. The result demonstrated Mn-doing boosted the redox activity and the amount of oxygen vacancies, which increased hydrogen gas generation. Hydrogen production displayed different behavior across temperatures due to detecting Fe2O3 and MnFeO3 phases for spent oxygen carriers. For the Fe2O3 oxygen carrier hydrogen gas yield is 1.67 Nm3/kg which is due to reduction of Fe2O3 phase to Fe3O4. However, the MnFe2O4 spinel phase detected in the spent MnFeO3 oxygen carrier is a reason for improving hydrogen gas yield to 1.84 Nm3/kg. Change reaction temperature from 900 °C to 850 °C reduced hydrogen gas yield from 1.84 Nm3/kg to 1.83 Nm3/kg for with MnFeO3 oxygen carrier. Regarding different steam flows, the proper flow rates that can maintain the formed phases and obtained best hydrogen gas yield are 80 and 90 μL/min, respectively. Meanwhile, the best hydrogen gas yield (2.21Nm3/kg) are obtained with MnFeO3 oxygen carrier at optimum conditions (850 °C and 90 μL/min).

On the operating parameters for hydrogen-rich syngas production in a plasma co-gasification process of municipal solid wastes and polypropylene using a constrained model in Aspen plus

Polypropylene and municipal solid wastes (MSW) are produced in large quantities presenting a serious environmental problem. Plasma gasification is one of the most environmentally friendly processes for the elimination of plastic wastes and MSW due to the high temperatures that guarantee that toxic compounds are decomposed. The feasibility of the plasma co-gasification of MSW and polypropylene wastes was investigated through a constrained model developed in Aspen Plus®. A parametric study was performed to investigate the effect of important parameters such as temperature, equivalence ratio, steam-to-waste ratio, and different ratios of polypropylene in the feedstock on the quality of syngas and hydrogen production. The good agreement of the model results with literature results ensures the robustness of the simulation's performance. The results suggest that the highest molar fractions of hydrogen are obtained with higher proportions of polyethylene in the waste mixture. Low air-to-waste ratios and low equivalence ratios are favorable to hydrogen generation. The amount of steam injected into the co-gasification system and temperature variation have a minor effect on hydrogen production. These findings could help launch plasma co-gasification industrial projects as a new waste-to-energy management method.

Recent advances in dynamic modeling and control studies of biomass gasification for production of hydrogen rich syngas.

The conversion of biomass through thermochemical processes has emerged as a promising approach to meet the demand for alternative renewable fuels. However, these processes are complex, labor-intensive, and time-consuming. To optimize the performance and productivity of these processes, modeling strategies have been developed, with steady-state modeling being the most commonly used approach. However, for precision in biomass gasification, dynamic modeling and control are necessary. Despite efforts to improve modeling accuracy, deviations between experimental and modeling results remain significant due to the steady-state condition assumption. This paper emphasizes the importance of using Aspen Plus® to conduct dynamics and control studies of biomass gasification processes using different feedstocks. As Aspen Plus® is comprising of its Aspen Dynamics environment which provides a valuable tool that can capture the complex interactions between factors that influence gasification performance. It has been widely used in various sectors to simulate chemical processes. This review examines the steady-state and dynamic modeling and control investigations of the gasification process using Aspen Plus®. The software enables the development of dynamic and steady-state models for the gasification process and facilitates the optimization of process parameters by simulating various scenarios. Furthermore, this paper highlights the importance of different control strategies employed in biomass gasification, utilizing various models and software, including the limited review available on model predictive controller, a multivariable MIMO controller.

Investigation of hydrogen-rich syngas production from biomass gasification with CaO and steam based on real-time gas release behaviors

Real-time gas release behaviors in biomass gasification using steam and CaO under various operating conditions were investigated by on-line gas analysis to mechanistically understand the enhanced production of hydrogen-rich syngas. Without steam and CaO, the syngas yields increased from 146.6 mL/g at 600 °C to 831.5 mL/g at 850 °C with improved cold gas efficiency (CGE) but corresponding to a low H2/CO ratio of 0.14. By introducing steam with CaO, the syngas yield further increased to > 1000 mL/g with 4 times growth in H2/CO ratio, and the CGE increased to 71.6%. The release of H2 was prolonged and intensified with the synergistic use of steam and CaO, while CH4 and CO almost unchanged. The increase in steam/biomass ratio mainly contributed to the elevated releasing rate of H2 after 6 min, and the growth in CaO dosage led to improved H2 evolutions all through the reaction period where the peak was from 33.1 mL/min∙g without catalyst to ∼100 mL/min∙g under catalyst/biomass = 2. Ternary diagram analysis indicated that CaO and steam with higher addition amount (e.g., CaO/biomass = 1, steam/biomass = 7.5) were more suitable for producing hydrogen-rich syngas with less CO2 emission and the elevated CGE. These synergistic effects were possibly due to that CaO addition in the presence of steam can catalyze the volatiles cracking and absorb CO2 to drive the chemical equilibrium of steam reforming and water gas shift reactions shifting forward, which consequently facilitated H2 formation. The current work will provide fundamentals for efficient conversion of biomass waste to high quality syngas.

Production of hydrogen-rich syngas via gasification of refuse derived fuel within the scope of renewable energy

The main challenge facing the globe is the rapid increase in population, energy consumption, and waste production. As a result, gasification might be regarded a favorable, cost-effective, and eco-friendly solution to this issue. In this study was carried out using an updraft fixed bed circulating gasifier transforming refuse derived fuel (RDF) into syngas. It was employed at 700°C, 800°C, and 900°C with a dry air rate of 0.05 l/min. The effect of temperature on syngas, which is the product of gasification, was observed. The maximum heating value of produced syngas was observed about 2900 kcal/m3 at 900 ˚C. As a result of the gasification process; conducted under optimum conditions, the concentrations of H2, CH4, CO were found to be approximately 45, 20, and 20 %, respectively. In conclusion, the gasification process is a suitable method for obtaining high-quality syngas from RDF materials that has a high calorific value.

Gasification of charcoal derived from tropical wood residues in an updraft fixed bed reactor

This paper aims to produce hydrogen-rich synthesis gas from the charcoal of three tropical tree species. The approach involves sequentially the production and characterization of charcoal, the production of syngas by air gasification; and then the determination of the composition of syngas. Proximal analysis of charcoal gave ranging from 6.10 to 7.05 %; 71.51 to 77.50 %; 20.14 % to 26 % and 1.83 % to 2.48 % respectively for moisture contents, fixed carbon, volatile matter and ash contents. The gas proportions of the syngas for the three wood species do not vary significantly, with hydrogen content ranging from 20.98 % to 21.88 %, carbon monoxide (CO) from 22.2 % to 23.29 %, H2/CO ratios between 0.91 and 0.98, and the calorific value of the syngas around 6.21 MJ/Nm3. The above results show that the wood residue charcoals of the three species used in this study are suitable for the production of hydrogen-rich syngas.

Facile synthesis of low-cost Co-Cu/C alloy catalysts for hydrogen-rich syngas production from low-temperature steam reforming of biomass tar

Recovering beneficial metal ions from industrial effluents by suitable support can be an efficient and environment-friendly way to prepare specific catalysts directly. Herein, modified lignite was developed as an ion exchange material and used to prepare Co-Cu bimetallic catalysts for hydrogen-rich syngas production from steam reforming reactions. For all the catalysts studied, Co75Cu15/600 (carbonization temperature at 600 °C) exhibits the optimal catalytic activity and stability in both steam reforming of toluene and biomass tar under low temperatures. Fresh and spent catalysts were detailedly characterized to investigate the metal interactions and catalyst deactivation. The introduction of Cu contributes to the formation of Co-Cu alloy and the lower particle size of Co (4.17 nm), thereby suppressing the carbon deposition, the oxidation of metals and the change of catalyst structure after reaction. Therefore, the inexpensive and readily-available Co-Cu/C has the potential to serve as a promising catalyst for large-scale biomass gasification technology.

Hydrogen-rich syngas production from straw char by chemical looping gasification: The synergistic effect of Mn and Fe on Ni-based spinel structure as oxygen carrier

Chemical looping gasification (CLG) is one of the promising ways to exploit biomass resources and produce hydrogen-rich syngas. In this work, two spinel oxygen carrier (NiMn2O4 and NiFe2O4) were studied for hydrogen-rich syngas production. A series of characterizations techniques including XRD, XPS, BET, SEM, TPR-H2 and TPD-CO2 were used to investigate the fresh and spent oxygen carriers. The result reveals that the NiMn2O4 oxygen carrier has higher reactivity and redox performance due to its higher oxygen vacancy concentration. On the other hand, the NiMn2O4 oxygen carrier obtain greater reactivity for hydrogen generation due to its phases and structure changes. NiMn2O4 oxygen carrier was reduced form (NiO)0.25(MnO)0.75 to (NiO)0.75(MnO)0.25 to Ni + MnO phases at 650-850 °C. Ni generated adhere to sufure of MnO, and the structure become loose and porous. And the more oxygen vacancise was formed. However, NiFe2O4 oxygen carrier showed different reduction behavior, it reduced from Ni1.25Fe1.85O4 to Fe2O3 + Ni3Fe phases at 650–850 °C. The formed Ni phase for NiMn2O4 oxygen carrier promote hydrogen gas generation (2.65Nm3/kg) at 800 °C. Based on the charaterize analysis, the proposed reaction process was explained. For the hydrogen-rich syngas production, the optimum conditions in this works shows at temperature (800 °C), steam flow (80 μL/min) and ratio of oxygen carrier with straw char (1:1).

Thermodynamic simulation of the co-gasification of biomass and plastic waste for hydrogen-rich syngas production

Co-gasification of biomass and plastics is a waste-to-energy conversion that reduces waste volume and enhances product quality, thus improving overall process efficiency. Thermodynamic equilibrium simulation of biomass co-gasification with plastic is studied using HSC Chemistry Software. Properties of effluent products are evaluated as product gas yields, higher heating value and carbon conversion efficiency to gas. Among different plastics tested, polypropylene is the most beneficial. Increasing plastic-to-biomass ratio, up to 5, improves hydrogen and CO yields and increases the HHV of the gas from 21 to 25 MJ/kg. Using CO2 as gasifying agent lowers H2 quantity due to reverse water gas shift reaction and reduces HHV. Air gasification decreases the HHV, compared to oxygen, due to N2 dilution effect. Steam is the highly efficient gasifying agent, and steam-to-carbon ratio of unity is a good compromise for high gas yield and heating value. Finally, thermodynamic data are validated with published experimental work.

Steam Gasification of Refuse-Derived Fuel with CaO Modification for Hydrogen-Rich Syngas Production

Steam gasification of refuse-derived fuel (RDF) for hydrogen-rich syngas production was investigated in a lab-scale gasification system with CaO modification. A simulation model based on Aspen Plus was built to study the characteristics and the performance of the RDF gasification system. The influences of gasification temperature, steam to RDF ratio (S/R), and CaO adsorption temperature on the gas composition, heating value, and gas yield were evaluated. Under the gasification temperature of 960 °C and S/R of 1, H2 frication in the syngas increased from 47 to 67% after CaO modification at 650 °C. Higher syngas and H2 yield were obtained by increasing both S/R and gasification temperature. However, as the CaO adsorption temperature increased, a lower H2 fraction was obtained due to the limitation of the CaO adsorption capacity at high temperatures. The highest H2 fraction (69%), gas yield (1.372 m3/kg-RDF), and H2 yield (0.935 m3/kg-RDF) were achieved at gasification temperature of 960 °C, S/R of 2, and CaO modification temperature of 650 °C. The variation trends of simulation results can match well with the experiment. The deviation was mainly because of the limitation of contact time between the gasification agent and RDF, uneven temperature distribution of the reactors, and the formation of tar during the experiment.

Development of high-performance nickel-based catalysts for production of hydrogen and carbon nanotubes from biogas

Selecting a suitable catalyst for implementing the simultaneous production of hydrogen-rich syngas and multi-walled carbon nanotubes through the integration of dry reforming and methane decomposition reactions has recently gained great interests. In this study, a series of bimetallic (NiMo/MgO) and trimetallic (CoNiMo/MgO, FeNiMo/MgO, CoFeMo/MgO) catalysts was prepared and evaluated for a catalytic activity of CH4 and CO2 conversions of biogas in a fixed bed reactor at 800 °C and atmospheric pressure. Among the investigated catalysts, the bimetallic NiMo/MgO catalyst showed the outstanding catalytic performance with 86.4% CH4 conversion and 95.6% CO2 conversion as well as producing the highest syngas purity of 90.0% with H2/CO ratio = 1.1. Moreover, the characterization of the synthesized solid products proved that the well-aligned structured morphology, high purity, and excellent textural properties of CNTs were obtained by using NiMo/MgO catalyst. On the other hand, using trimetallic catalysts which have the composition of Co and Fe leads to the severe deactivation. This could be attributed the catalyst oxidation with CO2 in biogas, resulting in the transformation of metals into large metal oxides. The integrative process with NiMo/MgO catalyst is regarded as a promising pathway, which has a high potential for directly converting biogas into the high value-added products and providing a green approach for managing the enormous amounts of wastes.

Hydrogen-rich syngas production form biomass char by chemical looping gasification with Fe/Ca-based oxygen carrier

Iron based oxygen carrier is attractive for chemical looping gasification due to its abundance, however it suffers low reactivity. Several materials have been utilized in the literatures to solve this issue, of which Ca is promising. In this work, iron has been modified by two Ca ratios to obtain CaFe2O4 and Ca2Fe2O5 oxygen carriers via sol–gel method. Oxygen carriers have compared in hydrogen-rich syngas production form biomass char in a fixed-bed system, and the effect of temperature and cycling ability have also considered. A series of characterizations including X-ray diffraction, scanning electron microscope, H2-temperature-programmed reduction, nitrogen adsorption and desorption and X-ray photoelectron spectroscopy were utilized to investigate the fresh and spent oxygen carriers. The result showed that the CaFe2O4 sample obtained an excellent H2 yield (0.87Nm3/kg) at 750℃ and oxygen carrier: biochar ratio of 1:1. Compared with gas–solid and solid–solid reactions at different temperature, the only CO and CO2 were produced in solid–solid reaction, and the conversion activity of CO into CO2 noticeable increase with raising temperature. On the other hand, the H2 is dominant component on production, and the H2 yield (2.0 Nm3/kg) was a maximum at 850 ℃. In the cycle experiment, the H2 yield was stable through 5th cycles. However, the Si generated by biochar cause the destruction of CaFe2O4, decreasing the CO production and conversion.