Chemical looping is one of the ideal processes for generating power and capturing CO₂ simultaneously without requiring additional energy. In this process, oxygen carriers are used for combusting solid fuels, and their activity should be improved to enhance energy efficiency in the process. In this study, we focus on the effect of K addition on the chemical looping reactivity of ilmenite (IL) used as an oxygen carrier. Scanning electron microscopy and X-ray diffraction measurements were performed to evaluate the K dispersion in K-added IL and the structural changes in IL by the K addition.

Hydrogen has been attracting increasing attention in response to the rising global demand for energy. This study investigates chemical looping combustion (CLC) as a promising technology for practical hydrogen production utilizing carbonaceous fuel. In the CLC process, hydrogen, CO₂, and oxygen-depleted air are separately extracted through the cyclic redox reactions of iron oxide with steam, fuel, and air, respectively. The hydrogen is separated from CO₂ and other byproducts during the process, thereby reducing the cost associated with hydrogen purification. Furthermore, when biomass is employed as the fuel, CLC offers a sustainable pathway for the production of renewable (green) hydrogen. In this study, a triple-fluidized bed hydrogen production system consisted of a fuel-reactor, a hydrogen-reactor, and an air-reactor is proposed to apply the CLC method. In the experiment, a thermogravimetric analyzer (TGA) was used to measure the reactivity of oxygen carrier particles, and the dependence of the hydrogen production rate on water vapor concentration and deactivation with repeated use were evaluated. In addition, steam gasification of char obtained from a triple-fluidized bed reactor was performed. Hydrogen production and CO, CO₂ emissions were also determined. The results can be used to determine the optimal temperature for the hydrogen-reactor of the triple-fluidized bed process.

In recent years, Japan has been focusing on the use of hydrogen in anticipation of global energy demand. This study focused on chemical looping combustion (CLC) as a practical hydrogen production technology using biomass. In the CLC process, oxygen carrier (based on iron oxide) particles are circulated while reacting with fuel, water, and air, enabling the simultaneous production of hydrogen, CO₂, and oxygen-depleted air, separately. In the experiment, a small-scale fluidized bed reactor was used to confirm whether iron oxide particles could be reduced to FeO since reduction degree to FeO is needed to produce hydrogen by introducing steam. The amount of supplied biomass was changed to determine the optimum feed to biomass to produce H₂. An operating guideline of 0.08 mol-H₂/kg-particle was obtained for K-ilmenite. The effect of coexisting gases (H₂O, CO₂) during particle reduction step on hydrogen production and char formation depended on type of oxygen carrier particles.

Hydrogen is attracting attention due to increasing global demand for energy. This study focused on chemical looping combustion (CLC) as a practical hydrogen production technology using renewable energy sources. In the CLC process, hydrogen, CO₂, and oxygen-depleted air can be simultaneously extracted by using oxygen carrier particles such as iron oxides with steam, fuel, and air. The hydrogen produced in this process is recovered separately from other gases such as CO₂, thus the cost of hydrogen separation can be reduced. In addition, when biomass fuel is used, “green hydrogen” production becomes possible. Therefore, in this study, a triple-fluidized bed hydrogen production system consisted of a fuel-reactor, a hydrogen-reactor, an air-reactor was built to apply the CLC method. Three types of iron oxide particles were used in the experiment: iron ore/alumina mixture, iron ore, and potassium-loaded ilmenite particles. Kerosene and woody biomass were used as fuels. Potassium-supported ilmenite particles emitted the highest amount of H₂ compared to the other particles. However, they also emitted a significant amount of CO₂. To prevent this CO₂ formation from the unburned char particles, it is necessary to gasify the char as much as possible in the fuel-reactor.

Torrefied Biomass Pellets (TBP) are a promising alternative fuel to coal for reducing CO₂ emissions. In this study, the combustion characteristics of TBP were evaluated by measuring the volatile matter (VM) content and the combustion rate constant of char using a Drop Tube Furnace (DTF) and an ash balance method. The results showed that the TBP contains approximately 90 wt% volatile matter, enabling rapid ignition and combustion. The remaining fraction primarily consists of char, and the combustion rate constant of char in the TBP was found to be equal to or greater than that of subbituminous coal.

The coke gasification process with CO₂ or H₂O was simulated and compared with experimental data. For both gasification reactions, the simulation initially overpredicted the experimental values, though showed good agreement as the reaction progressed. Furthermore, the overall pattern of the porosity distribution was consistent with the experimental results, confirming the validity of our simulation model.

In response to the need for a low-carbon society, the steel manufacturing industry has introduced hydrogen to partially replace fossil fuels in blast furnace operation. When hydrogen is injected, it generates a significant amount of H₂O in the gas phase and react with coke in the furnace. Therefore, understanding ash transformation during the H₂O gasification process is essential for mitigating coke performance in the blast furnace. In this study, to find the effect of temperature on ash behavior between CO₂ gasification and H₂O gasification, gasification experiments were conducted in CO₂ and H₂O atmospheres at different temperatures in target conversion ratio. To further characterize the composition and distribution changes of individual ash particles, computer-controlled scanning electron microscopy (CCSEM) analysis was performed, enabling quantitative assessment of compositional shifts under different gasification conditions.

In our coke ovens, a high blending ratio of low-volatile matter coal has led to a sharp increase pushing clogging. To mitigate this problem, coal blend optimization was examined with the aim of reducing pushing energy in the initial cycles. Laboratory tests demonstrated that (i) avoiding coals exhibiting high coking pressure at high temperatures secures clearance by allowing primary contraction, and (ii) increasing Total Inertinite promotes the formation of microcracks and suppresses large cracks. Consequently, the optimized blend showed improved contraction ratio and reduced coking pressure. Application in the plant resulted in approximately 7.5% reduction in pushing energy and a significant decrease pushing clogging.

To investigate the carbonization behavior of non-caking coal after pulverization and briquetting, polished

surface of coke samples carbonized at 500-900 °C were observed using a Scanning Electron Microscope (SEM). SEM

observations provided evidence of bond formation between coal particles during carbonization at 500-800 °C.

Elemental analysis of the coke samples revealed an increase in the number of condensed aromatic rings per aromatic

ring systems (ARS) with increasing carbonization temperature. These results suggest that the growth of ARS accelerate

the interparticle bond formation in non-caking coal during carbonization.

In this study, CO₂ and H₂O gasification experiments were conducted on coke derived from non-caking coal and coke derived from a mixture of non-caking coal and torrefied biomass, and the tensile strength of the samples before and after the gasification reaction was measured using a universal testing machine. Coke derived from a mixture of non-caking coal and torrefied biomass showed higher gasification reactivity than coke derived from non-caking coal and tended to have lower tensile strength. Additionally, when the CO₂ concentration was low and the H₂O concentration was high, the tensile strength increased at a comparable reaction rate.

β-zeolite was prepared using Vietnamese Quang Ninh coal ash containing multiple metal elements, with TEAOH as the structure directing agent and NaOH aqueous solution as the base. After cation exchange to the H-type, catalytic cracking of low-density polyethylene was performed using the Curie point pyrolizer method under the following conditions: LDPE 0.2 mg, catalyst 1.0 mg, carrier gas He 0.6 MPa, reaction temperature 500°C, reaction time 5 seconds. For catalysts prepared using colloidal silica with SiO₂/Al₂O₃ ratios of 13, 26, 39 and 52, the amount of acid sites decreased and the conversion tended to decrease as the SiO₂/Al₂O₃ ratio increased. However, the degree of crystallinity increased. Consequently, the catalyst with an SiO₂/Al₂O₃ ratio of 52 exhibited enhanced activity.

To utilize fly ashes derived from coal and woody-biomass combustion, adsorption behavior of phosphate ion by the ashes was evaluated. The adsorption isotherms of phosphate ion by the ashes were Langmuir-type, and woody biomass-derived ash showed a higher saturated adsorption capacity (74 mg-PO₄^3-/g) than subbituminous coal-derived ash (40 mg-PO₄^3-/g). When the ashes were heated under chlorine gas stream to convert the main components of ash, Si and Al, to valuable chlorides, the saturated adsorption capacity for P increased increasing temperature and time. Chlorination of the ashes at 1000°C for 1 h increased Ca content in the residual samples, and the saturated adsorption capacity increased five times that of untreated ashes. More than 90% of P adsorbed on the ashes and the residual samples was in forms (water and Peterman’s citric acid solution soluble) that could be directly absorbed by plants.

Some fly ash hardens in humid air, making it difficult to store and transport. It has been reported that calcium compounds such as calcium sulfate and ettringite are formed during the hardening process, but the characteristics of the ash that cause hardening have not been clarified. In this study, the calcium forms in ash that had hardened during transportation were investigated by Ca K-edge XANES analysis using synchrotron radiation light source. It was confirmed that calcium sulfate, sulfide, and hydroxide exist in the fly ash, and that the sulfide is converted to hydroxide during transportation. Calcium sulfide was added to fly ash that does not harden, and the hardening strength of the fly ash when exposed to humid air was measured using Vicat needle. It was found that the small amounts of calcium sulfide accelerate the hardening of the fly ash.

Humic acid, a plant growth promoter, was prepared from hydrochar obtained by acidic hydrothermal treatment of sugarcane leaves. Effect of hydrochar oxidation with HNO₃ on humic acid yield was investigated by varying the HNO₃ concentration, reaction temperature, and reaction time. The results showed that under conditions of high HNO₃ concentration and high reaction temperature, humic acid was decomposed into smaller molecules, resulting in a decrease in yield. Humic acid obtained from hydrochar oxidized with HNO₃ had lower C content, and higher N and O contents than humic acid prepared from hydrochar. In the presence of humic acid obtained from oxidized hydrochar, obtained by oxidation with 10 % HNO₃ at 50°C for 1 h, the root length of a model plant (Arabidopsis thaliana) was 1.8 times longer than in the case of humic acid from hydrochar. It was confirmed that oxidation of hydrochar with nitric acid increased the yield of humic acid and improved the plant-growth activity of humic acid.

Rice husks are discarded without effective utilization due to inconsistent composition and high ash content. To utilize them as a carbon source, it is necessary to remove the ash and make a homogeneous material. In this study, we focused on solvent extraction to resolve these issues. The objective was to improve the electronic conductivity of LiNi_0.5Mn_1.5O_₄ (LNMO), a cathode active material for lithium-ion batteries, by applying carbon coating using Soluble extracted from rice husks. Carbon coating on LNMO was applied by mixing Soluble and LNMO, heating at 150°C for 30 min in N₂ atmosphere, followed by heating at 330°C for 1 h in air. The thickness of carbon coated on LNMO(LNMO/C) was 10-45 nm. The charge-discharge performance at high current density of 10C showed that LNMO failed to perform charge-discharge cycles, LNMO/C exhibited a discharge capacity of 30 mAh/g. This result suggests that the coating of conductive carbon derived from Soluble on LNMO particle surface improved conductivity, thereby enhancing battery performance at high current density.

In recent years, research aimed at achieving carbon neutrality has gained attention, increasing interest in biomass utilization and the chemical conversion of carbon dioxide. This study investigates the dry reforming of ethanol obtained from biomass, where ethanol reacts directly with carbon dioxide to produce synthesis gas. Previously, we reported that adding Ag and Au to CuCeO₂ZrO₂, which exhibits activity for this reaction, improves both catalyst activity and product selectivity. In this study, focusing on the CuCeO₂ZrO₂ catalyst, we varied the raw materials for the CeO₂ and ZrO₂ supports and investigated their effects on activity and selectivity. Catalysts with high CeO₂ content showed high values in ethanol conversion, CO yield and H₂ yield, regardless of the preparation method. When the catalyst preparation method was changed, the catalyst prepared by the impregnation method showed higher activity and selectivity than the catalyst prepared by the sol-gel method.

To elucidate the spontaneous oxidation and heat generation mechanism of carbonized biomass, its molecular structure was analyzed and compared with that of coal. It was found that a carbonized biomass sample (BP-A) has bigger cluster sizes and shorter side chains than that of the coal known for its high spontaneous heating tendency. Furthermore, the ESR spectrum of BP-A was measured while switching the atmosphere from N₂ to O₂ under heating conditions. While the radical concentration increased in the coal, it decreased in BP-A. These results suggest that BP-A exhibits a different low-temperature oxidation and heat generation mechanism compared to the coal.

Characteristics of water sorption of torrefied biomass pellets were investigated by experimental and kinetic study. Two types of the pellets and two types of coals were soaked in distilled water at 25°C, 40°C or 60°C, and the moisture content of those during soaking were measured. Assuming water absorption of the 4 samples was in the second falling-rate period, an approximate solution to the diffusion equation was employed, and the values of parameters of B1 for the diffusion model were found to be approximately 0.8; therefore, the experimental results were fitted to the exact solution for the infinite plane sheet diffusion model. Moreover, extracted diffusion coefficients showed temperature dependence followed an Arrhenius relation.

The spontaneous combustibility of biomass char was investigated, focusing on the influence of feedstock type and pyrolysis atmosphere. EFB (empty fruit bunch) char exhibited a higher spontaneous combustibility compared with that of acacia and sorghum chars. This difference is attributed to several factors, including the varying proportions of the three main biomass components, the fundamental structure of lignin between woody and herbaceous biomass, and the presence of potassium in the ash. The study revealed that using steam during pyrolysis reduced the spontaneous combustibility at a fuel ratio of 6 or higher, which is believed to be due to the loss of active functional groups via the steam gasification reaction.

Recently a graphical method which was named “Pseudo Master Curve Analysis” has been presented by one of the authors to analyze an infinite number of parallel first-order reactions. In this paper the method was extended to analyze reaction systems which may consist of several n-th order reactions. The method allows us to estimate the number of reactions involved, the rate parameters of each reaction, and the consistency of experimental data rationally and easily. The applicability of the method was verified by applying it to the pyrolysis of a plastic (PE).

We have proposed a method to produce a substitute for coke feedstock by treating plastic waste at around 350°C under atmospheric pressure. We demonstrated that the chemical interaction caused by the heat treatment of mixed waste plastics allows the heat-treated material to partially replace coking coal without impairing the strength of the coke, even when mixed with coking coal.

To develop a method for producing pitch—a raw material for graphite and carbon-based materials—from non-fossil resources, we investigated the transformation of rosin, a natural resin component derived from pine trees, into pitch via a two-step chemical conversion process. This process involved catalytic deoxygenation/dehydrogenation/aromatization, and subsequent polymerization. The proposed methodology yielded a synthetic pitch with a high conversion efficiency of approximately 35% by weight. Elemental analysis confirmed the absence of nitrogen, sulfur, and ash, and the product exhibited favorable graphitization characteristics. These findings demonstrate the feasibility of producing graphite-compatible clean pitch, termed "green pitch," from biomass, thereby offering a promising route toward renewable carbon material synthesis.

Osaki CoolGen carried out the NEDO project “Biomass Co-Gasification of Technology Development for IGCC with CO₂ Capture” with the aim of further reducing carbon emissions by replacing part of the coal fuel with biomass fuel while utilizing existing technologies and equipment, and contributing to the realization of carbon neutrality. As a result, we have achieved that operating with a biomass blending ratio of 50% on a calorific value basis and have obtained prospects for commercialization.

This work investigated the reactivity of biomass char with activated ilmenite carrier using two-stage fluidized bedreactors.

CLC Poly-generation technology is assumed to be able to produce both electricity and hydrogen. It is believed that if the electrical load decreases, it can be shifted to produce hydrogen to maintain high energy conversion.

Co-firing coal with biomass is a promising strategy for reducing CO₂ emissions in coal-fired power plants. In this study, three types of bituminous coals (CV, TOP, and TN) were blended with woody pellets (KP) and black pellets (BP1), and the resulting ash particle morphologies were systematically investigated. Ash particles were classified into two categories: an Aggregate type, formed by solid-phase bonding, and a Melting type, formed by partial melting and solidification. The results demonstrated that both the type of biomass and the blending ratio significantly influenced the relative proportion of these particle types. In particular, co-firing with BP1 increased the fraction of Melting type particles, and at higher blending ratios their proportion approached that of Aggregate type particles. These findings indicate that the combination of coal type, biomass type, and mixing ratio plays a critical role in determining ash deposition behavior, and under certain co-firing conditions may increase the risk of adherent ash deposition on heat transfer surfaces.

In Waste-to-Energy (WtE) plants, ash particles originating from municipal and industrial waste tend to adhere to the surfaces of heat exchanger tubes. This adhesion leads to several operational issues, including decreased heat transfer efficiency, accelerated high-temperature corrosion, and reduced energy recovery. This study aims to develop novel surface treatment materials and techniques to mitigate ash deposition and corrosion under high-temperature conditions. Field tests were conducted to evaluate the performance of the newly developed material in an actual WtE plant environment. The results demonstrated that the new material significantly suppressed high-temperature corrosion caused by molten salts, showing superior performance compared to conventional SUS310S stainless steel.

In this study, we investigated the possibility of co-producing ironmaking raw materials (de0gangue metallic-Fe and modified-biomass with fluidity) and valuable materials (H₂ and organic acid) by alcohol/alkali treatment of iron ore and biomass (BM). H₂ and organic acids were coproduced by this treatment. In addition, it was possible to produce metallic-Fe with reduced Si, Al, and P contents. It was clarified that modified-BM acts as a binder for coke production when mixed with non-caking coal. The optimal conditions for producing H₂, organic acids, de-gangue metallic-Fe, and high-yield modified-BM were 220°C, 30min, amount of iron ore: ≤0.5g, NaOH amount: 5g, and particle size or iron ore: <100μm.

To understand the oxidation reactions of coal at low temperature, it is important to grasp the amount of oxygen consumed during the reaction and the behavior of gas generation. In this report, we measured the time-dependent changes in O₂ consumption and CO, CO₂ generation under constant temperature and atmosphere using a gas-flow-type coal oxidation apparatus. As a result, the decrease in O₂ concentration and the increase in CO and CO₂ concentrations followed the order: Coal X > Coal Y > Coal Z, which matched the previously evaluated order of heat generation. Furthermore, when comparing the amount of O₂ consumed with the amount of CO and CO₂ generated, it was found that the amount of gas generated as CO and CO₂ accounted for less than 15% of the O₂ consumed.

To analyze the low-temperature oxidation reaction process of carbonized biomass, isotope-labeled ¹⁷O₂ was used to measure the oxidation of carbonized biomass and the resulting CO and CO₂, which were then compared with coal. The carbonized biomass sample (BP-A) used in this study had a slow heat rate and, like coal with a slow heat rate, produced a small total amount of gases. However, the concentrations of ¹⁷O-containing CO and CO₂ were lower. This was likely since BP-A underwent minimal repeated chemical reactions caused by gas generation following atmospheric oxidation and the subsequential formation of reactive radicals.

CO₂ methanation is a promising reaction for reducing greenhouse gas emissions while producing methane as a useful fuel. In this study, Ni-supported BaZrO₃ catalysts with different calcination times were prepared, and the effect of calcination time on catalyst structural properties and CH₄ yield were investigated. The CH₄ yield obtained with Ni/BaZrO₃ catalysts calcined for 6 and 12 h was higher than that with the catalyst calcined for 24 h. At this time, the crystallite size of BaZrO₃ decreased with shorter calcination times, while the CO₂ adsorption capacity increased. These results suggest that the crystal growth of BaZrO3 does not proceed sufficiently with shorter calcination times, leading to the remaining of defects in part of the structure, which serve as active sites and consequently enhance the CH₄ yield.

The aim of this study was to extract kerosene-soluble components by hydrocracking Soluble prepared from biomass using bifunctional catalysts consisting of Y zeolite (solid acid) and hydrogenation-active metals. Only 24.5% TSKS components were obtained from the Soluble, but the TSKS yield increased significantly when hydrogenated at 350°C for 120 min using catalysts. In the case of TI component, the yield was 13.2% without catalyst, but decreased with PtY catalyst. On the other hand, the TSKI yield decreased when the NiY catalyst was used. These phenomena were discussed in terms of the hydrogenation ability and acidity of the catalyst.

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) is key to producing value-added chemicals from biomass. This study investigates the effect of nitrogen-doping of a carbon support on the dispersion of supported palladium (Pd) and its catalytic performance in HMF hydrogenation. Nitrogen-doping was found to be effective in enhancing the dispersion of the supported Pd nanoparticles. Furthermore, the product distribution in HMF hydrogenation was significantly altered by the use of the nitrogen-doped support, indicating a strong influence on catalytic selectivity.

In recent years, the reduction of iron ore using hydrogen instead of coke has been proposed with the aim of reducing

carbon dioxide emissions. Iron produced by hydrogen reduction does not contain carbon and is not suitable for use as a

product as it is. Therefore, this study focused on the addition of carbon to iron produced by hydrogen reduction and

conducted two types of experiments: basic research using ceramic tubes and experiments using a fixed-bed batch

reactor with added methane. In the ceramic tube experiment, we verified the conditions for CO generation. When

reduction was insufficient, C decomposed from CH₄ reacted with O in the iron ore fine, resulting in CO generation. In

the batch reactor experiment, we measured changes in reaction rates with temperature. We found that reaction rates

increased with higher temperatures, and that reverse reactions occurred when H₂ was present.