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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 Fe 2 O 3 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-H 2) 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 Fe 2 O 3 and MnFeO 3 phases for spent oxygen carriers. For the Fe 2 O 3 oxygen carrier hydrogen gas yield is 1.67 Nm3/kg which is due to reduction of Fe 2 O 3 phase to Fe 3 O 4. However, the MnFe 2 O 4 spinel phase detected in the spent MnFeO 3 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 MnFeO 3 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 MnFeO 3 oxygen carrier at optimum conditions (850 °C and 90 μL/min). • Mn-doped Fe 2 O 3 oxygen carrier shows greatest gas yield 2.21Nm3/kg at 850 °C and 90 μL/min. • Hydrogen production displayed different behavior across temperatures of Fe 2 O 3 and Mn-doped Fe 2 O 3 oxygen carriers. • The suitable steam flow can maintain phase formatted and reduced of Fe 2 O 3 and MnFe 2 O 4. [ABSTRACT FROM AUTHOR]

In biomass gasification, bio-oil is the main component of the condensable by-products. It is considered an attractive source for H 2 production via steam reforming. This study conducted acetic acid as a bio-oil model compound with LaNiO 3 perovskite catalyst due to its high oxygen vacancies and active sites. However, the perovskite structure of LaNiO 3 catalysis can be destroyed by produced H 2 gas, forming additional phases, including La 2 NiO 4 , La 2 O 3 and Ni. The LaNiO 3 and different phases were synthesized via a sol-gel method to probe its contribution and interaction with the H 2 gas produced from steam reforming of acetic acid. Through 300 min of reaction in steam to carbon (S/C) ratio of 3, the results showed that reduced-LaNiO 3 has stable H 2 gas production, while the other phases decrease with time. In particular, CH 4 is the main composition with the La 2 O 3 phase. A series of characterization techniques, such as XRD, BET, XPS, SEM, TG, H 2 -TPR and (CO 2 and O 2)-TPD, were utilized to investigate fresh and used samples. The results showed that the LaNiO 3 -reduced phase has high oxygen storage capacity, oxygen mobility, oxygen vacancies and surface area, preventing coke deposition. In contrast, the LaNiO 3 and La 2 NiO 4 phases have poor coke deposition resistance. • Ni/La 2 O 3 phase with LaNiO 3 catalyst play the main role in hydrogen-rich syngas production in steam reforming of acetic acid. • Ni/La 2 O 3 phase can easier produce amorphous coke. • Ni/La 2 O 3 phase has stable H 2 gas production throughout 300 min of reforming. [ABSTRACT FROM AUTHOR]

• NiMn 2 O 4 oxygen carrier shows great perform for hydrogen-rich syngas production at 800 °C. • NiMn 2 O 4 and NiFe 2 O 4 oxygen carriers shows different reduce pathway for Ni formatted. • The NiMn 2 O 4 and NiFe 2 O 4 oxygen carriers compares with reactivity. • The conditions for hydrogen-rich syngas production were considered at temperature, steam flow and ratio of oxygen carrier with straw char. 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 (NiMn 2 O 4 and NiFe 2 O 4) were studied for hydrogen-rich syngas production. A series of characterizations techniques including XRD, XPS, BET, SEM, TPR-H 2 and TPD-CO 2 were used to investigate the fresh and spent oxygen carriers. The result reveals that the NiMn 2 O 4 oxygen carrier has higher reactivity and redox performance due to its higher oxygen vacancy concentration. On the other hand, the NiMn 2 O 4 oxygen carrier obtain greater reactivity for hydrogen generation due to its phases and structure changes. NiMn 2 O 4 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, NiFe 2 O 4 oxygen carrier showed different reduction behavior, it reduced from Ni 1.25 Fe 1.85 O 4 to Fe 2 O 3 + Ni 3 Fe phases at 650–850 °C. The formed Ni phase for NiMn 2 O 4 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). [ABSTRACT FROM AUTHOR]

In this paper, a novel swirl multi-nozzle micromix combustor has been designed for the Integrated Gasification Combined Cycle (IGCC) gas turbine. The flame structure within the equivalence ratio of 0.3–0.9 and air flow speed of 30∼80 m/s was captured with OH* chemiluminescence measurements at atmospheric pressure and high air temperature (∼691 K). The flame structure characteristics were investigated and an intrinsic link between flame structure and stability was established. The results show that the peak flame axial OH* intensity was 1.44D∼1.89D from the nozzle exit. When the equivalence ratio increases, the single micromix flame transitions from a V-shaped (on the verge of blowing out) to an attached M-shaped (on the verge of flashback) flame, and the equivalence ratio of the transition increases with the flow rate increases. The flames were categorized into four characteristic structures, of which the corner flame morphology is an important basis for determining stability. [Display omitted] • V flame on the verge of blowing out, M flame on the verge of flashback. • The equivalent ratio for flame transit from V to M increases with the flow rate. • Flames near the inner shear layer are the core of the combustion. • The corner flame is a basis for determining the stability of the swirling flame. • Equivalence ratio does not affect the axial peak position of the OH* intensity. [ABSTRACT FROM AUTHOR]

• CaFe 2 O 4 oxygen carrier shows great perform for hydrogen-rich syngas production at 850℃. • Hydrogen gas is generated in gas–solid reaction, while, carbon oxidized react in solid–solid reaction. • CaFe 2 O 4 oxygen carrier shows stability after 5th cycles. • The different ratio of Fe/Ca formats oxygen carrier (CaFe 2 O 4 and Ca 2 Fe 2 O 5) and compared with reactivity. 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 CaFe 2 O 4 and Ca 2 Fe 2 O 5 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, H 2 -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 CaFe 2 O 4 sample obtained an excellent H 2 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 CO 2 were produced in solid–solid reaction, and the conversion activity of CO into CO 2 noticeable increase with raising temperature. On the other hand, the H 2 is dominant component on production, and the H 2 yield (2.0 Nm3/kg) was a maximum at 850 ℃. In the cycle experiment, the H 2 yield was stable through 5th cycles. However, the Si generated by biochar cause the destruction of CaFe 2 O 4 , decreasing the CO production and conversion. [ABSTRACT FROM AUTHOR]