Non-oxidizing Atmosphere Research Articles

Thermal stability of oxide-supported gold nanoparticles

In this study, we report on the influence of support and gas atmosphere on the thermal stability of Au nanoparticles on oxidic supports. All samples were prepared with a modified impregnation method and have initial Au particle sizes in the range of 3–4 nm. We observed that in air, Au nanoparticles on SiO2 and Al2O3 are thermally much more stable than Au nanoparticles on TiO2. For instance, upon treatment up to 700 °C, on SiO2, Au particles grew from 4 to 6 nm while on TiO2 from 3 to 13 nm. For Au nanoparticles on TiO2, growth is accelerated by oxidizing atmospheres and the presence of water and/or chloride. On non-reducible supports and in non-oxidizing atmosphere, the supported Au nanoparticles were remarkably stable. The insight into the growth of oxide-supported Au nanoparticles in reactive atmosphere offers an additional tool for a rational choice of a support for high-temperature gas-phase reactions involving gold nanocatalysts.

Robust super‐hydrophobic ceramic coating on alumina with water and dirt repelling properties

AbstractArtificial super‐hydrophobic surfaces are required for various applications. The super‐hydrophobic surfaces are usually made by applying a low surface‐energy organic coating on a highly textured substrate. A major problem with the as‐created surfaces is their poor durability. This problem is even severer for the surfaces created by applying the organic coating on inorganic substrates. The present study reports for the first time the all‐inorganic super‐hydrophobic surface created by modifying the inorganic substrates with polymer‐derived inorganic coating. A polydimethylsiloxane (PDMS) film was applied to an alumina substrate having flower‐like hierarchal micro‐nano surface texture, and then subjected to pyrolysis at 400°C in a nonoxidizing atmosphere. As a result, a SixCyOz ceramic coating with low‐surface energy methyl groups was formed on the alumina substrate. The as‐modified alumina exhibited super‐hydrophobicity with a water contact angle of 170° and a sliding angle of 5°. The super‐hydrophobicity was well retained after abrasion with sandpaper and exposure to boiling water and acidic solution. The super‐hydrophobic alumina demonstrated desired water repelling and self‐cleaning function. The method explored in this study could also be used for super‐hydrophobic surface modification of other inorganic materials such as glass and metals.

Thermal upgrading of nickeliferous pyrrhotite tailings: Formation mechanism of ferronickel alloy

Current practices of handling pyrrhotite (Pyrr) tailings pose the risk of acid mine drainage (AMD), which is a significant environmental problem. A thermal upgrading process by which nickel value can be recovered in the form of ferronickel alloy is a possible alternative to treat nickeliferous pyrrhotite tailings analyzing 0.5–1.5% Ni. The basis of this process is that the formation of ferronickel alloy from Pyrr is possible at kinetically favorable temperatures once the Fe/S ratio of Pyrr is shifted to stoichiometric or near stoichiometric FeS (troilite) with the addition of iron and/or removal of sulfur under non-oxidizing atmosphere. In this study, the formation mechanism of ferronickel alloy was investigated by treating diffusion couples at 850 °C to better understand the transport phenomena of sulfur, iron and nickel. When a compact of Pyrr powder was coupled with metallic Fe, the ferronickel alloy was found: (1) in the newly-formed sulfide layer adjacent to the remaining metallic Fe; (2) at the outer edge of the remaining metallic Fe; and (3) within the sulfide away from the metal/sulfide interface. The formation mechanism of ferronickel particles in different locations within the diffusion couple was linked to the various mass transport phenomena involved.

Hydrothermal improvement for 3R-CuFeO2 delafossite growth by control of mineralizer and reaction atmosphere

Delafossite CuFeO2 oxides were grown inside a hydrothermal reactor using Cu2O and FeOOH as precursors and NaOH as mineralizer. During this work the effect of the NaOH mineralizer and the reaction atmosphere was studied by varying the amount of NaOH used in the hydrothermal synthesis and by changing the reactor atmosphere from room air to high purity nitrogen. The oxides obtained were analyzed with Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDS), in order to obtain their morphological, chemical and structural characteristics. It was found that increasing the amount of mineralizer from 0.4 g up to 1.02 g improves considerably the hydrothermal reaction efficiency obtaining a resulting oxide with 93% of 3R-CuFeO2 phase and a subsequent decrease of the 2H-CuFeO2 phase. Moreover, using the same hydrothermal route it was shown possible to obtain high purity CuFeO2 compounds using small amounts of NaOH (0.4 g) if the reaction is performed under a non-oxidative atmosphere injecting pure nitrogen gas to the hydrothermal reactor where an increase of 3R-CuFeO2 phase from 36% to 94% was obtained. Finally, direct band gap of the semiconducting oxides were estimated using Tauc method from UV–vis spectra obtained by Diffuse Reflectance spectroscopy.

Oxidative Dehydrogenation of Ethanol over Vanadium- and Molybdenum-modified Mg-Al Mixed Oxide Derived from Hydrotalcite

Hydrotalcite or Mg-Al LDHs were synthesized by co-precipitation method. The Mg-Al mixed oxide was then derived by calcination of hydrotalcite at 450°C. The metal modified catalysts (Mo/Mg-Al and V/Mg-Al) were prepared by incipient wetness impregnation method. The obtained catalysts were characterized by several useful techniques and tested the reactivity for dehydrogenation and oxidative dehydrogenation of ethanol (gas-phase) to produce acetaldehyde. The catalytic reactions were performed at temperature range from 200 to 400°C for both non-oxidative and oxidative atmospheres. The results showed that the vanadium-modified hydrotalcite (V/Mg-Al) exhibited the highest ethanol conversion (34.3%) and acetaldehyde yield (15.5%) at 400℃ in the non-oxidative atmosphere. For the oxidative dehydrogenation of ethanol, the V/Mg-Al catalyst showed the highest activity at 400°C giving the ethanol conversion and acetaldehyde yield of 73.7% and 29.5%, respectively. This result probably related to the highest base density of V/Mg-Al catalyst (6.13 µmol CO2/m2) measured by CO2-TPD. The catalytic activity of Mg-Al catalyst and metal modified catalyst slightly decreased upon time-on-stream test for 10 h on oxidative dehydrogenation of ethanol due to carbon deposition.

Fluorination-Enabled Monolithic Integration of Enhancement- and Depletion-Mode Indium-Gallium-Zinc Oxide TFTs

Common metal-oxide thin-film transistors (TFTs) are unipolar (n-type) in nature, operating either in the enhancement-mode (EM) or depletion-mode (DM). A simple technology allowing easy monolithic integration of both EM and DM TFTs is desirable for improved performance of a metal-oxide circuit. In this letter, the channel regions of select TFTs in a circuit were fluorinated. These TFTs remained EM when subjected to a heat-treatment in a non-oxidizing atmosphere, while the rest was turned DM. The difference between the threshold voltage of an EM and a DM TFT can be simply and precisely modulated by controlling the heat-treatment temperature and duration. An inverter monolithically constructed of EM and DM indium-gallium-zinc oxide TFTs is presented as a demonstration.

Thermogravimetric analyses and kinetic modeling of three Cameroonian biomass

Pyrolysis and combustion processes of three Cameroonian biomass have been performed in a thermobalance to determine their thermal degradation profiles and the associated kinetic parameters. The samples were heated from ambient temperature to $$900\,{{}^\circ }{\hbox {C}}$$ under four low temperature rates (5, 10, 15 and $$20\, {{}^\circ }{\hbox {C}}\,\hbox {min}^{-1}$$ ) and under non-oxidative (nitrogen) or oxidative (synthetic air) atmospheres. The kinetic parameters associated with the pyrolysis of the different samples have been estimated either using a differential isoconversional method with two reaction functions or through the extended independent parallel reaction (EIPR) model and these sets of values are compared. Under nitrogen, the mean values of the activation energies obtained using a differential isoconversional method with Mampel’s reaction function are found equal to $$121.2\,{\hbox {kJ}}\,\hbox {mol}^{-1}$$ for oil palm kernel samples, to $$158.8\,{\hbox {kJ}}\,\hbox {mol}^{-1}$$ for movingui samples and to $$172.5\,{\hbox {kJ}}\,\hbox {mol}^{-1}$$ for padouk samples. When using the 3D diffusion function, the mean value of the activation energies is the same for the two first samples and increases to $$178.8\,{\hbox {kJ}}\,\hbox {mol}^{-1}$$ for padouk samples. When applying the EIPR model, the activation energies of the cellulose part (the main part of these lignocellulosic biomass) of the samples are, respectively, equal to 142.5, 155.2 and $$149.0\,{\hbox {kJ}}\,\hbox {mol}^{-1}$$ and do not highly vary with the applied temperature ramp. Under air, the values of the kinetic parameters have been determined using the EIPR model and the values of the activation energies slightly vary with the temperature ramp for the three samples.

The effect of torrefaction on oil palm empty fruit bunch properties using microwave irradiation

In this study, torrefaction via microwave irradiation was introduced towards oil palm empty fruit bunches (EFB) samples. The samples was fed into the alumina type crucible inside the microwave with the power input limit at 385W. Experimental was carried in non-oxidative atmosphere at 50 ml/min continous flow of nitrogen gas into the torrefaction system. The effects of main parameters from temperature, residence time were studied towards mass yield, energy yield, proximate analysis and hydrophobicity percentage Result revealed the increased of energy value up to 22.4MJ/kg for torrefied samples, whereby from proximate analysis mark the increased of fixed carbon percentage whilst volatile matter decreased. Torrefaction products also shows the ability of reducing of moisture uptake up to 60%, which is prudent the good grindability.

Durability Improvement of Pt Shell-Pd Core Structured Catalyst Via Poly-Dopamine Coating

1. Introduction It is of great importance to decrease Pt usage in PEFCs for cost reduction. Carbon supported Pt shell-Pd core structured catalyst (Pt/Pd/C) is a promising candidate for the decrease owing to high Pt utilization and ORR activity [1]. We found that ORR specific activity of the catalyst drastically enhanced with an accelerated durability test (ADT), while electrochemical surface area (ECSA) largely decreased due to agglomeration of the catalyst nanoparticles (NPs), resulting in a moderate increase of ORR mass activity [2]. Thus, it is essential to mitigate the ECSA decay for further enhancement of the ORR mass activity. In the present study, poly-dopamine coating was investigated to suppress the catalyst NPs’ agglomeration with the ADT and further enhance the ORR mass activity of the catalyst. 2. Experimental Pt/Pd/C catalyst was synthesized by a modified Cu-UPD/Pt displacement method [2]. 200 mg of Pt/Pd/C catalyst was added in 200 mL of 10 mM tris-HCl buffer solution (pH8.5) containing 2 mg/mL of dopamine hydrochloride and stirred at 30°C for 6 h under O2 gas bubbling (500 mL/min.), followed by filtering, washing and drying at 60°C in air [3]. ADT was performed at 80°C for 10,000 cycles in Ar saturated 0.1 M HClO4 by using a rectangular potential cycling of 0.6 V (3 s)-1.0 V (3 s) vs. RHE. Characterization of the catalyst was carried out by using TG, XRD, XRF, TEM and CV techniques. ORR activity of the catalyst was measured by RDE technique performed at 1,600 rpm in O2 saturated 0.1 M HClO4with positive scan rate of 10 mV/s at 25°C. 3. Results and Discussion It has been reported that polymerization of the dopamine was accelerated by O2and that poly-dopamine (PD) can be coated on various materials such as metals, metal oxides, organic films and plastics at low temperature (30°C) [3, 4]. For carbon coating, carbonization of the PD is carried out by heat treatment in non-oxidative atmosphere [5] and it has been demonstrated that size of the PD coated PtFe NPs (6.5 nm) did not change before and after the heat treatment at 700°C, indicating that the carbon coating using the PD precursor well suppressed coalescence and sintering of the NPs against the heat treatment [6]. In this study, we investigated effect of the PD coating on durability of the Pt/Pd/C catalyst without the heat treatment. Figure 1 depicts TEM images of the Pt/Pd/C catalysts before and after the PD coating and after the ADT performed at 80°C for 10,000 cycles. Little morphological changes were observed before and after the PD coating and agglomeration of the catalyst NPs was well suppressed after the ADT, which mitigated the ECSA decay of the catalyst with the ADT (Figure 2). Figure 3 summarizes change in ORR mass activity of the catalyst with the ADT. The ORR mass activity of the PD coated Pt/Pd/C catalyst was enhanced by 3.8-fold of a reference Pt/C catalyst (TEC10E50E, TKK), implying that the PD coating without the heat treatment, i.e., not a carbon coating, effectively mitigated the catalyst NPs’ agglomeration and improved the durability of the Pt/Pd/C core-shell structured catalyst. In the meeting, the durability of the heat treated catalyst will be also presented. Acknowledgement This study was supported by NEDO, Japan.

Engineering durable hydrophobic surfaces on porous alumina ceramics using in-situ formed inorganic-organic hybrid nanoparticles

Hydrophobic surfaces are required for a variety of applications owing to their water repellent and self-cleaning properties. In this work, we present a novel approach to prepare durable hydrophobic surfaces on porous ceramics. A polydimethylsiloxane (PDMS) film was applied to a porous alumina wafer, followed by pyrolysis at 400°C in a non-oxidizing atmosphere (H2:N2=5:95), giving rise to nanoparticles. In these particles, Si, C and O elements formed amorphous networks to which methyl groups that had survived the pyrolysis were bonded. The as-modified porous alumina wafer was hydrophobic with a water contact angle of 136°, which is attributed to the presence of the methyl groups. The hydrophobicity was maintained after immersion in aqueous solutions in a pH range of 2–12 and acetone. The hydrophobicity was also retained after exposure to temperatures as high as 450°C in an oxidative atmosphere (air) and after mechanical abrasion with sandpaper. The hydrophobic porous alumina ceramics developed in the present study are promising for use as membranes in various separation processes.

An oxidation-last annealing for enhancing the reliability of indium-gallium-zinc oxide thin-film transistors

The dependence of device reliability against a variety of stress conditions on the annealing atmosphere was studied using a single metal-oxide thin-film transistor with thermally induced source/drain regions. A cyclical switch between an oxidizing and a non-oxidizing atmosphere induced a regular change in the stress-induced shift of the turn-on voltage, with the magnitude of the shift being consistently smaller after annealing in an oxidizing atmosphere. The observed behavior is discussed in terms of the dependence of the population of oxygen vacancies on the annealing atmosphere, and it is recommended the last of the sequence of thermal processes applied to a metal-oxide thin-film transistor be executed in an oxidizing atmosphere.

Thermal resistant, mechanical and electrical properties of a novel ultrahigh-content randomly-oriented CNTs reinforced SiC matrix composite-sheet

Abstract Development of a thermal resistant CNT based sheet is important for high temperature engineering perspectives with multifunctional purposes. This work reports a novel CNT reinforced SiC matrix composite-sheet by polymer derived ceramics (PDC) processes using polycarbosilane as SiC precursor. The microstructure contains the amorphous SiC matrix (4 phases: SiC, SiC x O y , SiO 2 and free carbon), the chemical sharp CNT/SiC interfaces and the ultrahigh density multi-walled CNTs that are randomly oriented. The composite-sheet is thermally and mechanically stable in non-oxidizing atmosphere up to 1000 °C. The mechanical properties of the composite-sheet are significantly enhanced, with the Young's modulus increased by ∼7 times, and the tensile strength ∼4 times, compared to those of pure CNT sheet. The strengthening mechanism is a bridging effect of the SiC matrix to the CNTs to favor better load transfers during fracturing. Therefore, the composite-sheet shows an elastic-brittle fracture response, with limited CNT pull-out in the fracture surface after tensile test. Finally, the composite-sheet shows an excellent electrical conductivity that is also comparable to the pure CNT sheet, and is found enhanced after post heat-treatment at temperatures >800 °C in non-oxidizing atmosphere, presumably due to the more content free carbon formations in the SiC matrix.

Characterization and electrolytic cleaning of poly(methyl methacrylate) residues on transferred chemical vapor deposited graphene

Poly(methyl methacrylate) (PMMA) residue has long been a critical challenge for practical applications of the transferred chemical vapor deposited (CVD) graphene. Thermal annealing is empirically used for the removal of the PMMA residue; however experiments imply that there are still small amounts of residues left after thermal annealing which are hard to remove with conventional methods. In this paper, the thermal degradation of the PMMA residue upon annealing was studied by Raman spectroscopy. The study reveals that post-annealing residues are generated by the elimination of methoxycarbonyl side chains in PMMA and are believed to be absorbed on graphene via the π–π interaction between the conjugated unsaturated carbon segments and graphene. The post-annealing residues are difficult to remove by further annealing in a non-oxidative atmosphere due to their thermal and chemical stability. An electrolytic cleaning method was shown to be effective in removing these post-annealing residues while preserving the underlying graphene lattice based on Raman spectroscopy and atomic force microscopy studies. Additionally, a solution-gated field effect transistor was used to study the transport properties of the transferred CVD graphene before thermal annealing, after thermal annealing, and after electrolytic cleaning, respectively. The results show that the carrier mobility was significantly improved, and that the p-doping was reduced by removing PMMA residues and post-annealing residues. These studies provide a more in-depth understanding on the thermal annealing process for the removal of the PMMA residues from transferred CVD graphene and a new approach to remove the post-annealing residues, resulting in a residue-free graphene.

Thermal degradations of used cotton fabrics and of cellulose: kinetic and heat transfer modeling

The thermal degradations of small samples of different used cotton fabrics and of cellulose, in comparison, in a thermogravimetric balance are considered under non-oxidative (100% N $$_{2}$$ ) or oxidative (20% O $$_{2}$$ , 80% N $$_{2}$$ ) atmospheres and for different temperature ramps (5–50 K min $$^{-1}$$ ). The associated kinetic parameters are determined for low temperature ramps using a differential isoconversional method or an Extended Independent Parallel Reaction model, with different reaction functions, and they are compared. Because these values of the kinetic parameters do not simulate in an appropriate way the thermal degradations of the materials at higher temperature ramps, a heat transfer model is proposed, which brings corrections to the temperature really acting inside the samples. With these corrections, the experimental and simulated mass loss rate curves do better superimpose, which leads to values of the kinetic parameters which are independent of the temperature ramp.

Energy evaluation of biochar obtained from the pyrolysis of pine pellets

The wood pellets are mainly used in heating environments, commercial and residential, as well as fuel for production of thermal and electric energy in industrial plants. Furthermore, the heterogeneity and variable moisture content, combined with the high cost of transport, are limiting challenges that must be overcome with new technologies and new products. In this context, torrefaction and pyrolysis are attractive alternatives for increasing energy density and decreasing the moisture content of the samples, based on thermochemical conversion in a non-oxidizing atmosphere. Samples were produced to perform the energetic characterization of biochar from pine pellet using different heating rates 5–30 °C min−1, different residence temperatures 200, 280 and 570 °C and different residence time (1 and 0.5 h). The high heating value (HHV) of each variable was measured and allowed to observe that the heating rate did not influence of a significant way the results, in other words, a 5 % variation between the lowest and highest heating rate. Notwithstanding, the HHV was expressive compared to the pellet in nature, when it has been found an energetic gain over 80 %. In general, the biochar from pine pellets obtained by torrefaction or pyrolysis has appropriated characteristics compared to pellets in nature, showing a greater amount of energy per unit, high stability, reduced moisture content and reduced ash content. The kinetic of combustion to biochar in oxygen-rich atmosphere showed the dependence between the activation energy and conversion degree, with a continuous decrease in the activation energy, characteristic of complex processes comprised by initial reversible reaction followed by an irreversible one.

Thermal degradations of wood biofuels, coals and hydrolysis lignin from the Russian Federation: Experiments and modeling

The thermal degradation of wood biofuels (spruce, pine), of coals from different fields of the Russian Federation and of hydrolysis lignin is investigated using a thermogravimetric analyzer under different heating conditions and under non-oxidative or oxidative atmospheres. The samples are indeed submitted to a linear temperature ramp of 10K/min or to a temperature ramp of 200K/min up to a residence temperature between 250 and 450°C where they are maintained during 4h (isothermal conditions). The values of the kinetic parameters are determined for these different samples in both thermal conditions, either using the differential isoconversional method or by means of an Extended Independent Parallel Reaction (EIPR) model. The values of the kinetic parameters obtained with this EIPR model for spruce trunk are also compared with that of its main constituents (hemicellulose, cellulose and lignin).

Thermal degradation study of pure rigid polyurethane in oxidative and non-oxidative atmospheres

With a modelled building insulation rigid polyurethane foam (RPU) based on polymeric 4,4′-diphenylmethane diisocyanate and polyether polyol, thermal degradation mechanisms of RPU in oxidative and non-oxidative atmospheres were systematically investigated. In the condensed phase, results of thermogravimetric analysis (TGA) and in-situ Fourier transforms infrared (FTIR) spectroscopy in N2 and air showed that, presence of oxygen began to accelerate the thermal degradation at 120°C, whereas the communal reactions occurred 30–70°C delay in N2. In the gas phase, thermogravimetry- Fourier transform infrared spectroscopy coupled with gas chromatography and mass spectrometry (TG-FITR-GC/MS) was used and more than 20 characteristic products reflecting the structure and reaction routes were identified. With fruitful information of solid and gaseous products, it can be adequately deduced the mechanism of RPU thermal degradation at elevated temperatures in different atmospheres.

Pyrolysis characteristics and kinetics of biomass torrefied in various atmospheres

This study aims at investigating into the pyrolysis characteristics and kinetics of torrefied Norway spruce obtained from our previous work on development of a biomass torrefaction process integrated with oxy-fuel combustion. Thermogravimetric analysis technique was employed to study the effects of different torrefaction conditions (including various torrefaction atmospheres and different temperatures) relevant to oxy-fuel combustion on the pyrolysis behavior of the torrefied biomass. Thereafter, a global kinetic model with an assumption of a three-pseudocomponent mechanism was used for kinetic modeling and evaluation. The results showed that torrefaction temperature and oxygen concentration in torrefaction gas have significant effects on the pyrolysis peak height and peak temperature of the torrefied biomass. In addition, more hemicellulose was removed during torrefaction in CO2, compared with torrefaction in N2 and CO2/H2O. Moreover, high oxygen concentration in torrefaction gas and high torrefaction temperature can completely remove hemicellulose. The kinetic evaluation revealed that non-oxidative torrefaction atmospheres do not influent the pyrolysis kinetics of three main biomass components, but only their contribution factors. However, the presence of oxygen in torrefaction gas and the torrefaction temperature have significant effects on the kinetic data.

Development of an in situ temperature stage for synchrotron X-ray spectromicroscopy.

In situ characterization of micro- and nanoscale defects in polycrystalline thin-film materials is required to elucidate the physics governing defect formation and evolution during photovoltaic device fabrication and operation. X-ray fluorescence spectromicroscopy is particularly well-suited to study defects in compound semiconductors, as it has a large information depth appropriate to study thick and complex materials, is sensitive to trace amounts of atomic species, and provides quantitative elemental information, non-destructively. Current in situ methods using this technique typically require extensive sample preparation. In this work, we design and build an in situ temperature stage to study defect kinetics in thin-film solar cells under actual processing conditions, requiring minimal sample preparation. Careful selection of construction materials also enables controlled non-oxidizing atmospheres inside the sample chamber such as H2Se and H2S. Temperature ramp rates of up to 300 °C/min are achieved, with a maximum sample temperature of 600 °C. As a case study, we use the stage for synchrotron X-ray fluorescence spectromicroscopy of CuIn(x)Ga(1-x)Se2 (CIGS) thin-films and demonstrate predictable sample thermal drift for temperatures 25-400 °C, allowing features on the order of the resolution of the measurement technique (125 nm) to be tracked while heating. The stage enables previously unattainable in situ studies of nanoscale defect kinetics under industrially relevant processing conditions, allowing a deeper understanding of the relationship between material processing parameters, materials properties, and device performance.

Efficiencies of metal separation and recovery in ash-melting of municipal solid waste under non-oxidative atmospheres with different reducing abilities

Ash-melting of municipal solid waste produces molten metal that contains Fe and Cu, and melting furnace fly ash (MFA) that contains Pb and Zn. To recover the metal from the fly ash, Pb and Zn are extracted from the ash by water or enriched in the ash by washing out salts; this separation depends on their leachability. In this study, we investigated the effects of the reducing ability of the atmosphere on the efficiencies of metal separation during melting and metal recovery in water treatment. Different feedstocks (incineration residues) were melted under N2 or CO + N2 atmospheres. In some of the feedstock materials, volatilization of metallic Cu into MFA was promoted under the atmosphere with greater reducing ability (CO + N2). This increased volatilization inhibited the metal separation in the ash-melting process. Moreover, the higher reducing ability inhibited the formation of water-soluble lead chlorides and decreased the efficiency of metal recovery from the MFA because of the water leaching of the lead compounds. The reducing ability of the atmosphere is difficult to control uniformly in actual ash-melting plants, and we investigated appropriate melting conditions under which the effect of the reducing ability was minimized to promote metal separation and recovery. This minimization was achieved by melting incineration fly ash without additives with Cl gas treatment at 1400 °C.