As the hydrogen enrichment operation is being considered in the blast furnace to reduce the CO₂ emissions. Since the ash behavior of coke is one of the factors that deteriorate the permeability and stability in the blast furnace, it is important to understand the degradation behavior of coke during the H₂O gasification process. In this study, in order to find the effect of temperature on degradation behavior between CO₂ gasification and H₂O gasification, gasification experiments were conducted in CO₂ and H₂O atmospheres at different temperatures in 20% reaction ratio. Moreover, to investigate the pore behavior, we used the SEM to observe the cross-section of cokes.

Substituting air with either CO₂ or H₂O in the gasifying agents presents a viable strategy for promptly integrating a carbon-neutral energy vector into coal gasification technology, concurrently mitigating harmful particulate matter emissions. However, fully understanding the evolution of tar in the practical gasifier has proven to be challenging owing to complex mixture of the scale of reactors. This study presents a detailed kinetic investigation of tar and soot formations from the gas-phase reactions in the reductor of a two-stage entrained flow coal gasifier under oxy-fuel (O₂/CO₂, O₂/H₂O) atmospheres. The effects of temperature and coal types were studied. The results show that benzene, followed by naphthalene and phenanthrene, serves as the primary tar products. Higher temperature promotes tar reduction, especially under O₂/H₂O condition. Moreover, soot yield under the O₂/H₂O condition is less than that under the O₂/CO₂ condition owing to weaker hydrogen abstraction acetylene addition route. Soot yield decreases with the temperature rises. This work provides valuable insights and guidance for the reduction of tar and soot in the two-stage entrained flow coal gasifier under oxy-fuel atmospheres.

There is growing interest in the use of waste woody biomass as an alternative fuel to coal, because of its carbon neutral as an effective use of waste resources. To compensate for the low calorific value of biomass resources, we focused on biochar prepared by the lower-temperature pyrolysis. As the results, the calorific values and combustion conditions were improved to the same level as the used coal. Furthermore, the emissions of toxic polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 and PM₁₀ emitted during coal combustion were found higher than those of biochar. In the future, we would like to quantitatively evaluate PAHs generated in the entire processes, including during biochar preparation.

In recent large-scale pulverized coal-fired power plants, the co-firing of biomass fuels is being promoted to reduce carbon dioxide emissions per unit of power generation. One of the issues related to the biomass co-firing is the deposition and agglomeration of trace components in the boiler. In this study, we focused on silicon compounds as trace components that affect the combustion process. Silicon compounds are simultaneously combusted with biomass fuels, leading to the formation of silica particles, which can adhere to combustion boilers and cause performance deterioration, as well as contribute to atmospheric pollution as particles smaller than PM2.5. Therefore, countermeasures are necessary. The aim of this study is to investigate the combustion characteristics of organic silicon compounds and the behavior of silica particle formation within a pulverized coal combustion boiler. Siloxane, which is might be considered as one of the trace components in biomass, is used as a substitute for silicon compounds, and combustion experiments are conducted using a Drop Tube Furnace (DTF). The analysis of the generated particles provides insights into the formation behavior of silica particles under combustion conditions. When siloxane was combusted using the DTF (Drop Tube Furnace) apparatus, it resulted in the formation of primary particles consisting of white silica particles with amorphous structures at the nanoscale or below.

This study aimed to achieve continuous hydrogen generation through the direct reduction of iron sand with woody biomass. Increasing the biomass/iron sand mass ratio resulted in an increase in hydrogen production. However, supplying an excess of biomass had an impact on the fluidization within the fluidized bed, leading to a weakening of the reduction efficiency. In experiments where the particle size of the iron sand was varied, it was observed that larger particle sizes were advantageous. It is necessary to discuss the effects of these factors on iron content, thermal stability, and reactivity of the samples.

For the reduction of CO₂ emissions from pulverized coal power plants, utilization of biomass, such as wood pellet, is expected. However, there are some risks of self-heating and ignition of coal and biomass deposits in roller mill. In this study, effects of ambient temperature and biomass/coal ratio on self-heating propensities of biomass/coal deposits were evaluated by the wire-mesh basket tests. The results showed that the initial heat release rate of coal was affected by ambient temperature much more than biomass. Furthermore, the initial heat release rate of mixture was decreased with the increase of the ratio of biomass to coal.

CO₂ methanation is performed at 300-450°C and atmospheric pressure using Ni supported on CeO₂ or ZrO₂ as catalysts with moderate basicity. However, the cost of the catalyst is problematic. Therefore, the perovskite-type oxides, CaZrO₃, SrZrO₃ and BaZrO₃, which have moderate basicity, and BaZr_0.95Y_0.05O_3-δ, in which a part of Zr is replaced by Y and oxygen vacancies were increased, were focused on. In this study, the effect of Ni 10 wt% supported perovskite oxide catalysts on CO₂ methanation reaction at 300-450°C was investigated. Single-phase of perovskite oxides was seen in XRD patterns of the prepared catalysts. The CH₄ yields for Ni/SrZrO₃ and Ni/BaZrO₃ at 400°C were around 52 %, which was higher than that for Ni/CaZrO. CO₂-TPD analysis showed that CO₂ desorption of SrZrO₃ and BaZrO₃ was observed at higher temperatures than that of CaZrO₃, indicating that their basicity is stronger. Furthermore, the CH₄ yield using BaZr_0.95Y_0.05O_3-δ significantly increased to 69 mol%, suggesting that partial substitution of Zr for Y caused highly active the methanation reactions.

This paper reports a 3D computational fluid dynamics simulation of carbon dioxide (CO₂) methanation in a shell-and-tube reactor resolved to the catalyst geometry level. Fluid flow, heat transfer, and mass transfer are calculated, and the local distribution of gas and solid phases in the reactor is shown in detail. To generalize the simulation model, the catalyst effectiveness factor was treated as a variable, and the catalyst effectiveness factor equation and its parameters were investigated. As a result, the catalyst effective coefficient derived from the general Thiele modulus was the best agreement for the present computational model. For higher accuracy, the equations need to be improved to be more suitable for more reality models and chemical reaction equations.

The coke strength (DI) depends on coal blend ratio and operation conditons which are coal moisture content, coal particle size, coke oven temperature and more. Consequently, it is important for the target quality to predict coke strength at the time to decide coal blend. The conventional prediction method of DI has been obtained by an inductive model from the average coal properties. However, this prediction has often larger error because there is no additivity in some coal properties. Therefore, we try to predict DI with AI which makes a deductive model from coal blending ratio and time series parameters of an objective variable. As a result, AI prediction is more accurate than the conventional one for consideration of coal compatibility and adopting operation conditions as explanatory variables.

It is known that low bulk density region is formed around briquette when briquette is blended with power coal. To investigate the factors that form low bulk density region around briquette, low bulk density region around briquette was uantitatively evaluated when briquette was blended with several powder coals. In this time, low bulk density region around briquette was quantitatively evaluated as the product of the density difference from the powder part and the volume. As a result, it was confirmed that the formation of the low bulk density region around briquette was affected by the distribution and moisture of powder part.

In order to investigate the effect of heat treatment temperature and the chemical structures on the surface tension of coal, surface tension and ¹³C-NMR were measured for coal and semi-coke produced at the different temperature. The surface tension of coal slightly decreased by heat treatment at 300°C and increased as the heat treatment temperature elevated above 300°C. Based on ¹³C-NMR analysis, it was suggested that increase in surface tension of coal with increasing of heat treatment temperature caused by rise of the aromatic carbon ratio.

Ash deposition in pulverized coal-fired boilers can lead to operational issues and inhibit heat transfer. This study conducted combustion experiments using a laboratory-scale drop tube furnace (DTF) to investigate how adding biomass affects fly ash formation. During the experiments, two types of coal (CV and TOP coals) were mixed with black pine pellets (KP) and black pellets (BP) biomass samples at 5%, 15%, and 30% (based on anhydrous higher heating value). The study found that the particle size of fly ash increased as the biomass addition rate increased due to the reaction between coal mineral particles and biomass ash during combustion. An increase in aggregated-type particles was identified through shape classification of the produced ash using deep learning.

To develop a utilization of fly ash (FA) generated from coal-fired power plant, Si and Al oxides, which are the main components of FA, were converted into valuable chlorides by chlorination. FA was mixed with solid carbon and heated under chlorine stream at a maximum temperature of 1000°C. The chlorination rate was accelerated by planetary ball milling, and after chlorination at 1000°C for 1h, 84 % and 89 % of Si and Al were converted to SiCl₄ and AlCl₃, respectively, and the residue reduced to 16 % of the original ash. Generated chlorides were recovered in the cooling section set at 100°C and -40°C, and 90.8% of volatilized Si was distributed to the condense at lower temperature section, and the purity of Si was 95.1%.

Part of the ash generated during the combustion process of solid fuels such as pulverized coal can adhere to the surface of heat transfer tubes, causing heat transfer inhibition and impairing boiler operation. In this study, the physical properties of three types of coal were compared to evaluate the shape classification of fly ash. In addition, the accuracy of the shape classification was investigated by using deep learning, including the use of training images, various parameters, and data expansion, as well as the relationship between the shape classification and melting properties based on thermodynamic equilibrium calculation. We utilized deep learning to categorize the morphology of fly ash particles and analyzed the formation process of particles, considering the thermophysical characteristics of coal ash.

Catalytic methane decomposition on Fe/γ-Al₂O₃ to generate hydrogen is kinetically discussed utilizing TG experiments. Effect of hydrogen in the reaction gas should be examined for hydrogen production. It was found that a significant deactivation of the catalyst is observed in the pure CH₄ atmosphere, and hydrogen in the reaction gas can suppress the deactivation of the catalyst significantly, Steady state activity could be obtained at 650 °C in the presence of hydrogen, and this phenomenon is significantly dependent on the reaction temperature. Equilibrium constants could be determined using non-isothermal experiments. Initial reaction rate is also examined, and the activation energy of the rate constant could be determined to be 69 kJ/mol.

With concerns over the depletion of coking coal, there is a need to convert low-grade carbon resources and organic wastes into raw materials for coke making. In this study, we have proposed a method to produce a binder for coke making by co-processing biomass waste with heavy oil or waste plastic at around 350°C under normal pressure and the validity of the proposed method was investigated. Co-processing was conducted using cedar as biomass waste, residue of vacuum distillation of oil sand bitumen as heavy oil, and polystyrene as plastic. It was found that co-processed cedar and heavy oil or cedar and co-processed polystyrene had high performance as a binder to improve the strength of coke.

Carbon deposition on coke oven wall is one of the factors inhibiting operation, making it important to manage wall carbon deposits. This paper reports on a newly developed method for evaluating wall carbon. The measurement method involves filling a sealed experiment container processed from bricks with coal, hot charging it, and allowing the thermally decomposed gas from carbonization process to come into direct contact with high-temperature bricks. This became possible efficient collection of wall carbon deposits while suppressing the generation of roof carbon deposits and soot.

Coal was reacted with ¹⁸O₂ and H₂¹⁸O respectively in a closed cell by heat treatment at 60 °C, and the resulting evolved gases were quantified by isotope. As a result, CO and CO₂ containing ¹⁸O were confirmed under both conditions. H₂¹⁸O was also observed in the reaction with ¹⁸O₂.

From the above, it was found that there are chemical reactions in which water contributes to the low-temperature oxidation of coal and reactions in which water molecules are generated.

To clarify the mechanism of spontaneous oxidative exothermic reaction of coal, we have been analyzing the molecular structure of coal before and after oxidation. As a result, radical formation during the oxidation reaction was suggested. Therefore, in this study, ESR spectral measurements were performed while the coal was heated under an oxygen atmosphere. The higher the spontaneous exothermicity of coal, the more radicals increased immediately after the switch from nitrogen to oxygen in the atmosphere. This is expected to lead to a more detailed elucidation of the mechanism of natural heat generation in coal in the future.

Autoxidation mechanism for methyl-hexabenzocoronene was investigated by a reactive molecular hyperdynamics simulation. The simulation results at 270°C and 0.1 MPa for 16 ns were consistent with weight gain and product distribution experimentally obtained at 270°C and 0.1 MPa in 30 minutes. The atom trajectory analyses indicated that hydrogen peroxide and water play critical roles to form oxygen-containing functional groups, which could be overlooked in conventional autoxidation mechanisms.

Osaki-CoolGen Project, which was complex three-phase demonstration project, aimed to achieve ultimately efficient coal-fired power generation with near-zero emissions by integrating oxygen-blown Integrated Coal Gasification Combined Cycle (IGCC) - carbon capture technology with fuel cells. In the first phase we verified the basic performance of IGCC. In the 2nd phase and 3rd phase we verified the performance of IGCC with CO₂ Capture and confirmed the prospect of Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC) in March 2023.

To develop a technology to promote plant growth in salt-affected environments, humic acids were prepared from a peat and a biomass (sugarcane leaf), and the plant growth-improving effect of the obtained humic acids were confirmed by hydroponic cultivation of Arabidopsis thaliana. The original sugarcane leaf contains small amounts of humic acid-like substances, and humic acids were generated by hydrothermally treating the leaf in acidic and alkaline aqueous solutions. Addition of humic acids derived from peat and hydrothermal treated sugarcane leaf significantly recovered the germination ratio and root growth of Arabidopsis thaliana in the presence of NaCl. It was confirmed that humic acid derived from hydrothermally treated sugarcane leaf is more effective in reducing the stress that plants receive from NaCl than humic acid derived from peat.

Currently, Japan is dependent on imported coal, oil, and natural gas for resources. Therefore, the utilization of biomass, which are carbon neutral and abundant in Japan is needed. This study evaluated the CO₂ gasification of parts of zelkova tree char: trunk, branches, and bark. The CO₂ gasification was operated at atmospheric pressure and temperature was raised to 900°C with TG-DTA and product gas was analyzed GC-TCD. The results showed that the bark had a gasification start temperature ~ 30°C lower than the other parts of the tree. The highest amount of CO production was observed in the trunk, about 1.6 times higher than in the bark due to the higher carbon content in the trunk and the presence of reaction inhibitors such as silicon (Si). Therefore, CO₂ gasification of the bark has the advantage that it can be performed at relatively low energy. CO₂ gasification of the trunk has the advantage of producing more gas per mass.

Based on the idea that the process of convertinglow calorific value solid fuels such as brown coal and biomass into thermalenergy by combustion is inefficient, we have proposed a new process to convertthese low-grade fuels into electricity and hydrogen without relying on thermalenergy conversion, taking advantage of their high chemical reactivity. This paper outlines the new proposed process.

We investigated the use of deep learning for shape classification of ash sampled from actual pulverized coal boilers to evaluate the ash deposition phenomenon. As a method, images of individually sorted ash particles were classified into seven different shapes and evaluated with each of the five ash samples. The result showed that the number and mass distributions of each shape were characterized differently with samples. Based on the mechanism of ash deposition on heat exchange tubes, “fine” and “agglomerated” particles were thought to be involved in ash deposition. It was considered that these particle shapes could be used as a new method to evaluate the ash deposition phenomenon.

Stable operation of coal gasifier is the key subject for practical use of Integrated coal Gasification Combined Cycle (IGCC). It is necessary to maintain the gasifier temperature above the slag fusion temperature in order to ensure stable slag discharge. This temperature has been determined by the standardized coal ash fusion temperature measurement, which requires a lot of work and time. Therefore, in order to improve the operability of IGCC, coal ash fusion temperatures were predicted using ash composition and symbolic regression technique in this study. As a result, we have identified several key factors and a preferable estimation formula.

The degradative solvent extraction is well-known as one of the biomass reforming methods. In this method, a solid product containing a large amount of carbon can be extracted as Soluble from biomass at mild temperatures between 300-350°C in a non-polar solvent. In this study, the degradative solvent extraction of lignin and cellulose was performed to clarify the extraction mechanism of Soluble from biomass. Further, the addition of deep eutectic solvents (DES), which have an ability to cleave the bonds between carbon and oxygen in biomass, were also examined to increase Soluble yields and reduce oxygen content. The addition of DES decreased Soluble yield and oxygen content for lignin, while the addition of DES tended to increase the Soluble yield and decrease the oxygen content for cellulose.

In woody biomass or waste to energy plants, high temperature corrosion of boiler tubes, such as active oxidation which is caused by alkali chlorides has become a serious problem. In this study, the active oxidation of metal specimens in the presence of NaCl was evaluated with Thermogravimetry - Differential Thermal Analysis (TG-DTA) to elucidate the mechanisms and establish the highly practical solutions for the corrosion. As a result, the active oxidation had a dependency of the metal composition, and there was a correlation between increments of metal specimens with TG isothermal tests and decrements with immersion corrosion tests.

Some ash particles in municipal and industrial waste adhere to heat exchanger tube surfaces, which causes problems such as heat-transfer inhibition, high temperature corrosion and low utilization in Waste-to-Energy (WtE) plants. The objective of this study is to develop new surface treatment materials and techniques which can decrease the ash deposition and the corrosion. In this paper, mechanisms of NaCl-induced accelerated oxidation were evaluated through TG-DTA, hightemperature corrosion test, and understanding of reaction kinetics.

In the hydrogen production process within a chemical loop, the utilization of redox reactions of metal oxides is expected to facilitate the generation of high-purity hydrogen. This research aims to employ iron sand as the metal oxide and biomass as the reducing material. It investigates the particle size, shape, and fluidization characteristics of the iron sand during the chemical loop reaction, with the objective of achieving multiple cycles. The study also examines the influence of factors such as gas flow rate during reduction in the chemical loop and the ratio of biomass to iron sand on the particle size of the iron sand.

In this study, waste bamboo materials from abandoned bamboo groves were used as an alternative to plastics for the preparation of biomass-based products. Waste bamboo materials was thermally liquefied in a polyhydric alcohol mixture (10-30%) containing a sulfuric acid catalyst and cyclic carbonic acid. Optimization of conditions during thermal liquefaction, such as solvent composition, acid catalyst addition rate, and reaction time was investigated. The chemical structure, molecular weight distribution, and hydroxyl value of the liquefied product obtained were analyzed. It has showed that a liquefaction rate of 80% in 60 minutes was achieved with a reduced sulfuric acid catalyst ratio in 2% in a solvent with 20% ethylene carbonate. Therefore, it is possible to reduce the environmental impact of the preparation of resins and other products from liquefied biomass products.

In this study, liquefaction processes were performed for zelkova and sawtooth oak wastes collected in Saitama City, Japan, divided by site. The reaction conditions were decided using a medium-temperature acid catalyst method to investigate the effects of biomass type, temperature, acid catalyst amount, and solvent amount on the properties of the liquefied products. As a result, biomass liquefaction proceeded at once up to 60 minutes and then slowed down. It was also suggested that prolonged liquefaction beyond 60 minutes may cause an increase in molecular weight due to recondensation, which may affect the utilization of the liquefied product as a resin. Furthermore, the performance of polyurethane foams (PUFs) prepared under various conditions using the liquefied products obtained by liquefaction was investigated through biodegradation and functionality evaluation tests, with the aim of developing PUFs using these liquefaction products.

From our previous studies, we found that CuCeO₂ZrO₂ composite catalysts prepared by the sol-gel method showed good activity in the CO₂ reforming reaction of ethanol. In the present study, we aimed to further improve the activity by modifying CuCeO₂ZrO₂ composite catalysts with Au addition. AuCuCeO₂ZrO₂ composite catalyst improved the ethanol conversion, and the yields of H₂ and CO were maximized for the 2Au8Cu45Ce45Zr catalyst. TG-DTA measurements of the catalysts after the reaction suggested that Cu metal species of the active catalyst would be less susceptible to oxidation, facilitating the transfer of oxygen to the carbonaceous species to produce CO, which led to decrease in the coke formation for 2Au8Cu45Ce45Zr catalyst.

Into a zeolite-Al₂O₃ composite prepared by the kneading method was supported Pt using the impregnation method. The catalyst obtained was used for hydrocracking of n-heptadecane to produce jet fuel. 0.5Pt/Y(100)35A, where 0.5 means wt% of Pt, Y means zeolite type, 100 in a parenthesis means SiO₂/Al₂O₃ ratio and 35 means wt% of Al₂O₃, exhibited the high selectivity for jet fuel of 74%, the conversion of 99% and the high yield of jet fuel of 73% at 295℃. In contrast to this, 0.5Pt/Z(110)35A, where 0.5 means wt% of Pt, Z means ZSM-5 zeolite, 110 in a parenthesis means SiO₂/Al₂O₃ ratio and 35 means wt% of Al₂O₃, exhibited the increase in gaseous products, the low selectivity for jet fuel of 22%, the conversion of 97% and the low yield of jet fuel of 21% at 270℃.