X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) spectroscopy, supplemented by other techniques, have been used to investigate the concentrations, solubility, and chemical speciation of sulfur and other key elements (As, Fe, Se, Zn) in ambient PM_2.5 samples collected in Lexington, KY, a location in the eastern central USA that is surrounded by many coal-burning electricity generating stations. The goals of the investigation were (i) to identify how these elements occur in PM_2.5, with emphasis on S, Fe and Zn because they have been implicated (albeit weakly) in epidemiological studies as agents in PM_2.5 that are potentially harmful to humans, and (ii) to establish the significance of emissions from coal-fired power plants contributing to ambient PM_2.5 in Lexington.

In this study, we conducted coal gasification experiments by electrical drop tube furnace. In the experiments, we used Low Pressure Impactor (LPI) for the particle sampling in different particle size. Captured particles are dissolved in the acid on each particle size and the trace element concentrations of the solutions in the particles are analyzed by ICP-AES. For the consideration of the result of the experiments, we conducted thermodynamic equilibrium calculations. Calculation results support to investigate the chemical compounds of trace elements in the gasification atmosphere.

The purpose of this research is to discuss the effect of physically-mixed Fe₂O₃ on the steam gasification behavior of Indonesian Adaro subbituminous coal (AD) and Japanese cedar (SG) mixture (1:1 in weight ratio) in 50 vol% H₂O/He atmosphere at 800°C for 1 h. The calculated amount of hydrogen evolution for the AD+SG sample, which was calculated by the sum of the amount of hydrogen evolutions for AD (87 mmol/g-char) and SG (82 mmol/g-char), was 86 mmol/g-char, but the actual hydrogen amount for the AD+SG sample was around 100 mmol/g-char. The sum of the amount of hydrogen evolution for Fe₂O₃-AD and Fe₂O₃-SG was around 121 mmol/g-char. On the other hand, Fe₂O₃-AD+SG could produce around 152 mmol/g-char of hydrogen, which was much larger than the calculated value. In this study, this increase in the amount of hydrogen evolution could be explained by the change in the form of the iron catalyst and the char structure during the pyrolysis stage.

The work studied the Oxygen carrier was further examined in a small fluidized bed reactor with coal char as fuel. The effect of oxygen carrier on coal char gasification gases in containing both H2 and CO was investigated by comparing the gasification behaviour of the (H2 + Oxygen carrier) and (CO + Oxygen carrier).

The authours have been investigating the effect of steam injection to IGCC gasifier to achieve higher thermal efficiency. Decreased temperature in gasifier is expected by injected steam, and we clarified that gasification reactivity and char characteristics were affected by pyrolysis temperature in the experiments of a sub-bituminous coal (AD coal). In this study, the effects of pyrolysis temperature on char gasification reactivity and characteristics were compared between AD coal and a bituminous coal (KZ coal). KZ char samples with various thermal histories were prepared with DTF, and gasified under CO2 or steam condition with TGA. Gasification reactivity of KZ char prepared at lower pyrolysis temperature was higher as with the case of AD char, while the difference was limited. Char characteristics were analyzed with XRD, STEM-EDX, and XAFS. The growth of graphitization, the dispersiveness of iron in char and the chemical forms of iron in coal were different between coal types.

Catalytic reaction of biomass cellulose into C₃ and C₄ light hydrocarbons over Pt supported catalyst was investigated. Pt supported on NH₄⁺-form ultra-stable Y type (NH₄-USY) zeolite catalyst (Pt/NH₄-USY) enabled direct conversion of cellulose into C₃ and C₄ hydrocarbons without hydrogen and other expensive reagents. Results revealed that 1wt%Pt/NH₄-USY(14) catalyst showed higher C₃+C₄ hydrocarbon yield than 1wt%Pt/H-USY(14). The yield reached 14.5C-% during reaction over the 1wt%Pt/NH₄-USY(14) at 443 K for 72 h reaction. Furthermore, because of their structural sensitivity, Pt/zeolite catalysts with Pt particle larger than 5 nm showed higher TOF values than catalysts with Pt particle smaller than 5 nm. The high index {311} facet was observed on Pt particles only when the Pt particle size was 5 nm or larger, suggesting that hydrocarbon formation mainly proceed over the facet.

Spontaneous combustibility of Indonesian lignite was studied with field test of 150-ton simulated pile and numerical simulation of the stockpile. The experimental results showed that the temperature of the coal was significantly increased from the bottom and outer part of the stockpile. 3D numerical simulation was performed for better understanding of the experimental results. The simulation predicted that the increase of the oxidation reactivity and the air permeability leads to increase of the spontaneous combustibility. Moreover, the results indicated that the higher air permeability leads the hot spot location more inner and upper part of the stockpile.

Mozambique has a great potential in terms of coal deposits, the most important is Moatize Coal Basin (MCB) located in Tete Province, Moatize district. The MCB has estimates reserves of about 2.5 billion tons, with thick coal seams allowing the open-pit exploitation. It is well known throughout the world that Moatize basin is a world class deposit for coking and thermal. However, recently, occurrences of spontaneous combustion are being resisted in both in situ coal seams and stockpiles of washed products (coking coal and thermal coal). Spontaneous combustion is a direct result of self-heating and it is a global issue affecting environment, economy and human health.

In this study, petrographic and chemical properties of samples of raw coal (in situ layers), coking coal and thermal coal were studied using image analysis through oil immersion microscopy and elemental and proximate analyzers (CHN, CS and TGA-DTA) respectively, to predict the propensity of self-heating. The microscopic characterization revealed important features such as changes in vitrinite reflectance, oxidation rims, micropores and cracks mainly on in situ coal and some signs of weathering and oxidation on thermal coal which are related to their reactivity and potential to self-heating leading later to spontaneous combustion

Low temperature oxidation mechanism of coal was investigated under the condition of 40~80°C in humid atmosphere. CO and CO₂ were the major products in each condition and the formation rate of CO₂ was larger than that of CO. Moreover, the formation rate of CO and CO₂, especially at the initial stage of the reaction, was larger at the temperature above 70°C. It is expected that the major reaction was different between the initial stage and the following stage, and the formation and decomposition of the peroxides were the key reactions in low temperature oxidation mechanism.

To remove nitric oxide (NO) in flue gas at low temperature, photochemical reaction using vacuum ultraviolet (VUV) was examined at room temperature. The wavelength of VUV was 172 nm. NO was converted to N₂, NO₂, and HNO₃. The products were controlled by the gas residence time. NO removal was increased in an increase of the gas residence time, about 100% removal was attained at the gas flow rate of 1.0 L/min. At the flow rate of 5.0 L/min (short residence time), removed NO was mostly converted to HNO₃ and NO₂. Contrary, the amount of HNO₃ and NO₂ was a little at long gas residence time though NO removal was high. Reaction mechanism of NO removal by VUV irradiation was proposed.

The efficient ammonia synthesis at a low temperature and an atmospheric pressure are desired to storage hydrogen generated by excess solar power. Ammonia production from nitric acid (HNO₃) may be an alternative technique for hydrogen storage. Reaction characteristics of reduction of HNO₃ using hydrogen with metal catalysts was investigated in this study. Ammonia production using Ni catalyst and hydrogen gas bubbles was examined at atmospheric pressure at the temperature of 60 °C. A 78.4 % yield was obtained at reaction time of 4 hours. The amount of the Ni catalyst strongly affected the yield of NH₄⁺.

To develop a mild chemical desulfurization method without residual chemicals in the treated Hyper-coal, desulfurization behavior was investigated by oxidation using hydrogen peroxide and acetic anhydride at room temperature and by pyrolyzing the treated sample under nitrogen stream. XANES analysis showed that the Hyper-coal contained only thiophenic sulfur and that the thiophenic sulfur changed to sulfone during the oxidation treatment. High removal extent of sulfur with high char yield was achieved by pyrolyzing the oxidized sample prepared at room temperature for 24 hour.

In a series of studies on the development of coal utilization process with pre-desulfurization, three types of coal were extracted by 1-methylnapthalene and sulfur distribution from raw coals to products (Soluble, Residue and Deposit) was clarified. XANES analysis indicated that most of pyritic sulfur was distributed to Residue. Soluble contained no inorganic sulfur. Every Soluble obtained from three types of coal contained organic sulfur, especially thiophenic sulfur only. Thiophenic sulfur content in Soluble decreased linearly with the increase of the steps of extraction using an ionic liquid of imidazolium type.

Desulfurization of bitumen was performed by combination of oxidative desulfurization (ODS) and ultrasound irradiation. Tetrahydrofuran (THF) was employed as solvent to emulsify the bitumen and improve the desulfurization ratio. In the result, the desulfurization ratio reached to 82.7% (ion-exchange water: 52%). We also investigated simultaneous recovery and desulfurization of bitumen from oil sand using ODS and ultrasound. Recovery ratio of bitumen from oil sand was 68.1% and the purity of recovered bitumen was 72.3%.

In a coal-fired power plant, the lightness of gypsum in the desulfurization process decreases when the unburnt carbon amount in gypsum increases. In this paper, we investigated the contamination mechanism of unburnt carbon in gypsum. As a result, it was found that unburnt carbon in gypsum is porous and has fine coal ash in its pores. We assume that the ash influences the unburnt carbon density and electrical resistivity and therefore decreases the collection efficiency of unburnt carbon in the electrostatic precipitator.

Selective recovery process of titanium, vanadium and tungsten has been developed for the spent denitrification catalyst produced from coal fired plant. Volatilization behaviors of the rare metals were followed in a chlorine gas stream with the addition of carbon as a reducing agent. Methanol vapor was supplied to a fixed bed of catalyst at 400 °C and fine carbon was deposited on the surface of catalyst. The volatilization rates of the rare metals ware enhanced drastically with the use of the deposited carbon compared to pyrolytic carbon prepared from phenolphthalein. The rare metals in the catalyst could be recovered selectively at 400 °C without silicon, iron and aluminum when the deposited carbon of 20 wt% was used.

In this study, we have prepared Cu and Zn-loaded carbons (brown coal and activated carbon) and evaluated the catalytic activity of these samples for a methanol synthesis reaction. The results revealed that methanol synthesis activity depended on the types of the carbon support and pretreatment temperature of the CuZn-loaded catalysts. The methanol yield per copper weight of CuZn-loaed activated carbon treated at 550°C was three times higher than that of a commercial catalyt, Cu/Zn/Al₂O₃.

Characteristics of tar reforming on a coal char were investigated. The difference of pyrolysis duration to producing char clearly affected the tar reforming activity. Two char samples having different production condition were employed for coal tar reforming in a drop tube reactor. The tar produced from the coal pyrolysis was effectively reformed on the coal char prepared with longer pyrolysis duration, while was not so effectively on that prepared with shorter pyrolysis duration. It was revealed that properties of the char such as pore and carbon structure and/or functional groups affected the tar reforming characteristics.

The blast furnace operation of low reducing agent rate and high pulverized coal rate (PCR) operation is required to reduce CO₂ emission. It is important to improve combustion efficiency of pulverized coal at high PCR operation, so better coal brand is selected for higher combustion efficiency. On the other hand, obstruction in a carrier piping and decrease of carrier amount occurs because of adhesion among pulverized coal particles by using a certain coal brand. In this study, we researched the relation between the shape of pulverized coal particles with different coal rank and the adhesion force of pulverized coal particles. The shape of particles were analyzed by an image analysis equipment and the degree of circularity was calculated. The tension stress of pulverized coal powder layer was measured and the adhesion force of between particles was calculated by corrected Rumpf equation. As the result, we confirmed the degree of circularity of particle affected the adhesion force.

Hyper-coal (HPC) is low ash coal produced by the solvent de-ashing technology. Coal is thermally (380 °C) extracted into the coal-derived solvent. HPC has excellent thermoplasticity and large potential for coke additive to make a strong coke. Also, the low impurity of HPC it can be used for carbon material. The yield of HPC depends on the coal solubility. Therefore, it is important for HPC process to optimize extraction condition to increase extraction yield. In previous research, we researched the effect of heating rate by bath test and continuous bench scale units (BSU) and that the extraction yield was increased with increasing heating rate. But it is unknown what components extracted in rapid heating process.

In this research, we evaluated compared HPCs produced by rapid heating method and by conventional heating (slow heating) method in BSU. HPC is analyzed molecular distribution, chemical structure, fluidity, and distensibility.

It is known that inert materials such as coke breeze have an influence on the fissure formation behavior of the coke cake. But, In changing fissure formation, it’s to assume that it changes how to crack of coke. Therefore, in order to investigate how to crack of coke, we applied the Gaudin-Meloy-Harris size distribution function to coke. It was found that coke breeze make the α-value decrease and anisotropy of crack increase.

To investigate effects of coke properties on the crack forming of coke, a three-dimensional model for the cokemaking process was developed, and thermal stress analyses coupled with heat conduction analyses were performed using the finite element method. As a result, a stress was concentrated at a crack tip. The concentrated stress would propagate the crack during carbonization. Furthermore, the intensity of the stress at the crack tip was dependent on interval and depth of crack and viscosity of sample. These results suggested that the crack interval and viscosity of sample affected the formation of the crack.

We investigated the influence of various reagents on the liquidity of coal to improve the fluidity of low grade coal. A low fluidity coal and reagents including amine type aromatic and oxygen-containing aromatic were mixed so that the reagents mass ratio was 10 mass%. The mixed sample was charged in a vessel for measuring the fluidity and heated to a re-solidification temperature at 3 °C/min to measure the maximum fluidity and the softening temperature range. Among the added reagents, it was found that addition of oxygenated aromatic compounds deteriorated the fluidity of coal. On the other hand, improvement of fluidity was observed at the time of addition of amine type aromatic. Among these, it was confirmed that the softening initiation temperature of coal was greatly shifted to the low temperature side when phenothiazine was added, and the maximum fluidity was greatly improved.

Addition of coal-tar pitch composed of poly-aromatic hydrocarbons to coal increases its dilatation of coal. In this study, we investigated the effect of organic compounds on the maximum dilatation (MD) for hard coking coals （MD = 107）. Twenty organic compounds with different carbon skeletons and functional groups were used. The value of MD increased with increasing the boiling point of coal samples. With regard to increasing of MD, the effect of addition of 9,10-dihydrophenanthrene (ΔMD = 25) was larger than that of phenanthrene (ΔMD = 7), which is probably because hydrogen at 9 and 10 positions inhibits polymerization of coal structure. Although the value of MD little changed by addition of a liner aliphatic hydrocarbon (C₂₈H₅₈), that drastically decreased due to addition of anthraquinone with carbonyl carbon (ΔMD = -43).

To expand the coal resources for power generation, R&D of Australian Loy Yang brown coal reforming technology has been conducted. Australian brown coal has the character of high moisture content, low calorific value and high spontaneous combustion property etc. In order to change Loy Yang coal properties suitable for power generation coal, the drying and carbonizing technologies were studied. In this paper, drying technologies was discussed. It was found that the moisture content of Loy Yang coal can be decreased from 60% to 50% under 60 °C by using fluidized bed dryer.

Co-combustion of coal and woody biomass is caught on coal fired power generation in order to reduce CO₂ emission. Measures to increase the co-combustion rate of woody biomass are being studied for the purpose of achieving a larger CO₂ reduction. So, torrefied pellet have attracted attention in order to increase energetic density and to improve grindability.

Physical properties (water absorbability, brittleness), low-NOx combustibility and electrostatic precipitator property were investigated as practical characteristics evaluation when torrefied pellet were used in coal boilers.

Oxy-Fuel IGCC system is expected to be a promising power generation system achieving both high thermal efficiency and low carbon emission. CO₂ concentration in a gasifier becomes higher than that in a conventional gasifier, hence basification behavior in a gasifier under high CO₂ concentration should be clarified prior to specific gasifier design. In this study, the effect of operation condition on the gasification behavior in the Oxy-Fuel IGCC condition was numerically investigated. Results showed that although coal gasification is occurred both combustor and reductor, gasification reaction in combustor is rather dominate. Moreover, Higher R/T condition increased coal gasifier performance. This is due to the fact that heat generated partial oxidation is effectively used by coal gasification without heat loss from the gasifier wall in higher R/T case.

The gasification reaction occurred in coal gasifier has not been expressed in chemical reaction formula because coal is a mixture of various chemical components contain unknown materials. We represented coal by CH_mO_n, where m and n were atomic ratios H/C and O/C respectively, and expressed gasification reaction by following formula, CH_mO_n+αO₂+βH₂O→γH₂+ΔCO+εCO₂+ζH₂O+ηCH₄. We have succeeded to derive some numerical expressions that represent material and thermal balances as a function of carbon conversion and oxygen ratio. It is important to make clear the scientific meanings of CH_mO_n and above reaction formula for further development of this stoichiometric analysis. The implications of CH_mO_n was examined mathematically assuming that coal is an aggregate of N kinds of components. Let ‘i-th ’component be n_i moles of C_aiH_biO_ci, coal can be represented by a numerical expression, ΣN i=1 (n_ia_i) CH_bi/ai O_ci/ai. We come to the conclusion that CH_mO_n is a mean chemical formula of coal, and gasification formula mentioned above is an averaged reaction formula of every constituent molecules in coal.

The coal’s self-heating is a risk when coal is stored in thermal power station. The characteristic of coal’s self-heating at normal temperature (20-80 degrees) was researched, because when coal was stored was at normal temperature. First, the influence of the heat generated when H₂O adsorbed coal was examined. When humidity was changed, the calorie generated from coal was measured by the calvet calorimetry. As a result, the characteristic of the moisture absorption heating was almost corresponding with the evaluation of coal’s self-heating based the experience in our company. Next, the heat generated when oxygen adsorbed coal was measured. As a result, there is a kind of coal with a large influence of the oxygen adsorption heating. In conclusion, the measurement of the heat generated when H₂O adsorbed coal is effective as the evaluation method of coal’s self-heating. Additionally, the evaluation method of coal’s self-heating improves by the method of evaluating the heat generated when oxygen is adsorbed.

A sensitive TG-DSC enabled the measurement of heat of adsorption/desorption of water on/from coal accurately at over 100 °C. This technique was applied to measure the heat of desorption of water during the thermal drying of as-received coal first. Next, the role of adsorption of water vapor on the dried coal in relative to coal-oxygen interaction was examined The transient changes of heats of adsorption/desorption of water on the way to reach equilibrium were also successfully estimated and discussed in relation to isosteric heat of adsorption/desorption and heat of vaporization of water.

An extraction method, which we call degradative solvent extraction, produces high quality extracts having similar physical and chemical properties from several types of low rank coals and biomasses. Three solid fractions, Residue, Deposit, and Soluble, were obtained from the extraction method. Residue is expected to be utilized as a high quality solid fuel because of its high heating value comparable to subbituminous coal. When the extraction product was not fractionated, we obtain solid upgraded product “solvent treated coal” (STC). STC is also expected to be a high quality solid fuel. To evaluate the potential of Residue, and STC as high quality solid fuels, estimation of their propensity to spontaneous heating is essential in addition to their heating values and rates of combustion and/or gasification. This work examines the propensity to spontaneous heating of Residue and STC prepared from two low rank coals using an index proposed in presentation, No.2-3.

In the gasification process, the reaction rate of biomass-derived char (hereinafter referred to as bio-char) is extremely slow. Therefore, it is necessary to overcome this drawback and investigate mechanisms to accelerate the reaction. In this study, the gasification of bio-char was activated by using a catalyst (Fe), which is a typical alkali metal. In addition, the mechanism for improving the gasification rate of bio-char, on which Fe was loaded, was examined by analyzing the elements on its cross section in detail and the pores by measuring the specific surface area and the pore diameter. The results obtained in this study are as follows: (1) when Fe was loaded on bio-char, although there were closed-pores in the initial stages of gasification, pores rapidly developed with the increase in carbon conversion; (2) α-FeOOH and α-Fe₂O₃, which could not be impregnated into bio-char immediately after Fe-loading, were mainly dispersed from being laminated on the surface into pores on the surface, to support gasification with the increase in carbon conversion; Fe partially moved into the bio-char after α-FeOOH and α-Fe₂O₃ were reduced; and (3), because the Fe-catalyst was difficult to volatilize and remained in the bio-char, the pores continuously developed until the end of gasification.

Air oxidation experiments of low rank coals ranging from 40 to 600 °C were performed using a TG-DSC analyzer by a TPR method. Weight changes and heat generation rates measured were analyzed by the so called distributed activation energy model (DAEM). With the rate analysis performed at constant temperatures below 150 °C, the rate equations covering all reaction stages were successfully formulated. Three reactions with the activation energies, E, of 7 to 46 kJ/mol below 150 °C, several reactions with E = ～50 to ～100 kJ/mol at 150 to ～280 °C, and two reactions with E = 100～110 kJ/mol and 40～150 kJ/mol over ～280 °C were found to represent the oxidation of two low rank coals.

This paper aims to clarify the effect of kaolin addition on fly ash emission during air combustion of two low-rank coals (coal A and coal B). The raw coals were mixed with 10 wt% kaolin and then combusted in a lab-scale drop tube furnace at 1400 °C. The particle size ranges of kaolin used were < 45 μm, 45 ~ 106 μm, 106 ~ 150 μm, 150 ~ 250 μm and 250 ~ 500 μm. The resulting ash was segregated as bottom ash, fine ash (cyclone ash), and ultrafine ash (LPI ash). The influence of the particle size of kaolin added on the ash partitioning was examined. The results indicated that, adding the kaolin with the particle size of 106~150 μm during coal combustion caused the lowest fly ash emission compared to the combustion of raw coal or the mixture of raw coal and kaolin with other particle size ranges. The ultrafine ash with particle size less than 0.5 μm generated from the combustion of the mixture of coal A with the kaolin (106~150 μm) was decreased relative to raw coal combustion.

In this study, a new experimental apparatus in which the spherical flame propagation of coal particle cloud in a homogeneous turbulent flow field can be conducted has been developed. By employing the developed experimental apparatus, the effect of the turbulence intensity on the flame propagation of bituminous coal particle cloud was investigated. As a result, it was found that the flame propagation velocity increases with increasing turbulence intensity. This is considered to be caused by that the area of flame leading edge is increased with the turbulence intensity, same as the gaseous fuel flame propagation.

The Osaki Coolgen Project began in April 2012 as an “Integrated coal Gasification Fuel Cell combined cycle (IGFC) demonstration project” subsidized by the Ministry of Economy, Trade and Industry. This project aims to realize innovative low-carbon coal-fired thermal power generation that combines IGFC, an extremely efficient coal-fired thermal power generation technology, with innovative CO₂ capture technologies. The first stage of this project, to demonstrate the oxygen-blown Integrated Coal Gasification Combined Cycle (IGCC), started in March 2017. The following will explain the project outline.

Several molecular weight (Mn) determination method were compared on a saturate fraction separated from atmospheric residue of oil sand bitumen by alumina column chromatography. Mn measured by cryoscopic method is available for samples having Mn < 500, and gas-chromatographic distillation is also available for those having both H/C atomic ratio>1.7 and atmospheric boiling range < 700 °C, but Mn by GPC was overestimated using polystyrene standards.

The activated carbon with large surface area (about 2500 m²/g) was able to be prepared from the mixture of Loy Yang coal and melamine by chemical activation using K₂CO₃. The mixed K₂CO₃ was changed to KOCN at 400°C. At 700°C, this KOCN reacted with the carbon in the char and then the specific surface area was increased. In this method, metallic potassium was not generated and there was no danger of ignition.

Integrated gasification combined cycle (IGCC) is believed to be an advanced coal power generation system because of its high efficiency. It is inevitable to develop the power generation system with carbon dioxide capture and storage (CCS) according to the Paris Agreement. In this study, oxy-fuel IGCC coupled with CO₂ recirculation for CCS is examined from the viewpoint of exergy analysis. Exergy analysis shows that much exergy lost in syngas cooler and heat recovery steam generator in the base process, in which the heat is recovered by water/steam. In the improved process, the heat is firstly recovered by CO₂ and O₂ to higher temperature, and the rest is recovered by water/steam. Net electrical efficiency of the improved process reaches up to 54.6% (HHV), and is higher than the base process by 6.7%.

Flexible operational performance, plant efficiency improvement and O&M (operation and maintenance) optimization are increasingly required due to market changes such as deregulation of electric market, introduction of renewable energy and etc. Therefore, we are engaged in developing ICT platform and various kinds of applications software consisting of three service categories, such as “operation improvement”, “performance improvement” and “O&M optimization”.

A newly developed system, which aims to automate boiler combustion tuning using artificial intelligence (AI) technique, has been demonstrated in the coal fired boiler, and we verified that AI combustion tuning are comparable to a highly skilled engineer. For AI combustion tuning system, we built high accuracy prediction models for each process values considered in combustion tuning e.g. NOx, UBC. Using the prediction models, the AI combustion tuning system can estimate boiler characteristics according to operation conditions and find optimal adjustment parameters.

Decreasing of activity of the denitration catalyst caused by arsenic adsorption is one of the big problems against the stable long term operation of the coal power plant. In order to remove arsenic from the catalyst by conversion of As₂O₅ to volatile As₂O₃, methanol was used as the carbon source for the reduction. Effects of treatment temperature, reaction time and partial pressure of methanol on changes in the removal extent of arsenic, the chemical forms of vanadium and the denitration activity were investigated.

We have proposed a novel highly-efficient power generation method in which biomass or low-rank coal reduces liquid phase inorganic media and subsequently electric power is generated by electrochemical oxidation of the reduced media by air. Whereas power generation efficiency by biomass or brown coal using a conventional boiler is only 10–20 %, theoretical power generation efficiency of the proposed method can be estimated to be as high as 80 % if VO²⁺ or Cu²⁺ is employed as inorganic media for example. In this study it is experimentally confirmed that the reduction of candidate inorganic media, VO²⁺ and Cu²⁺, by biomass or brown coal can proceed at as low as around 250 °C. Formation of by-products that may retard the electrochemical oxidation could successfully be suppressed by properly selecting the reaction conditions. These results suggest the possibility of realizing the proposed method.

A woody biomass, Leucaena, and a grassy biomass, rice straw, were subjected to a degradative solvent extraction method that treats them in a non-hydrogen donor and fractionate the product to three fractions: Soluble, Deposit, and Residue at 350 °C. One of the challenges for the practical application of the method is to find cheap and locally available solvents instead of expensive 1-methylnapthalene (1-MN) which we have used as a model solvent. In this work, we proposed to use two petroleum based solvents: kerosene (abbrebiated to KS, b.p. = 170 °C) and a distillate of oil refinery that is rich in benzene derivatives (A150, b.p. = 180 °C). The validity of the solvents on the solvent treatment was examined by reference to 1-MN. The results showed that the thermal degradation behavior of the biomass in the three solvents was rather similar and was controlled by temperature. The Soluble yields from Leucaena were respectively 4.6, 16.1, and 20.7%, and the Soluble yields from rice straw were respectively 6.4, 18.5, and 29.3% for KS, A150, and 1-MN. Detailed characterization of the Soluble showed the possibility of potential utilization of the Soluble from the two petroleum based solvents as a high quality fuels or precursors of carbon materials.

Hyper-coal (HPC) process, a thermal extraction process of coal, uses methylnaphthalene-like solvent, presupposes the solvent recycling. It means that there is no need to replenish the fresh solvent from outside. To perform this, coal-derived oil, which is distillable fraction produced by the thermal decomposition reaction of coal, will be utilized as the solvent. Solvent loss will be replenished by the coal-derived oil repeatedly, and composition of the coal derived oil will become the equilibrium composition. Therefore, to satisfy the necessary and sufficient condition for solvent recycling, the process has to produce enough quantity and quality of the coal-derived oil. Recent study revealed that several percent on coal of oil production satisfied the quantitative requirement, and coal-derived oil consisted with compounds having naphthalene ring structure (80%) and benzene ring structure (20%)³⁾. Influence of exiting such benzene ring compounds in the solvent to the extraction and sedimentation performances were investigated in this study. A model solvent, consisting 20wt% of p-xylene, performed rather decreasing in coal extraction yield compare to 1-MN. On the other hand, it performed rather increasing in the sedimentation velocity. It was considered that xylene influenced to the solid agglomeration behavior to change the boundary settling.