Quantitative estimation of particulate matter (PM) pollution from coal combustion, which is one of the major anthropogenic emission sources in China, is urgently needed to better understand transboundary pollution in the East Asian region. As a first step, we conducted laboratory experiments for the mass spectrometric characterization of fly ash from coal combustion using a fluidized bed reactor. Here, we report detection of notable signals at m/z 85, 87, and 133 in mass spectra for organic species obtained by an Aerodyne quadrupole aerosol mass spectrometer (AMS). Nine different coals, six of which were mined in north-east Asian region, were tested with three different combustion temperatures. The results showed that signals at m/z 85, 87, and 133 were significantly larger than those at the adjacent m/z, with similar observations having been made in different field studies carried out in western Japan. The m/z 85 to m/z 87 ratios were reproducible over the coals tested, suggesting the potential usefulness of these for fingerprinting coal combustion PM. The average ratio with the standard error of the mean was 2.8 ± 0.1. While the m/z 133 to m/z 87 ratios varied more, the mean ratio with the standard error of the mean was 1.5 ± 0.2, and the results were still reproducible. A comparison of the m/z 85 and 133 to m/z 87 ratios from other studies that also used AMS suggests that the ratios obtained in the current work are distinctive from those for vehicular emissions, plastic burning, and cooking emissions, but close to those for biomass burning. Despite this similarity, the results here still offer useful information for source identification of PM with the use of AMS measurements.

The characteristics of in situ coal tar reforming with char were investigated. Subbituminous coal was continuously fed and pyrolyzed at 1173 K in a drop-tube reactor in the presence of additional char. The ratio of the additional char to coal was varied to clarify the effect of the amount of the additional char on tar reforming. The effect of the operation pressure was also evaluated. The experimental results showed that the heavier tar having more than four ring aromatics decreased with the increase in the amount of char. The reforming reaction of the heavy tar with additional char was somewhat restricted with the increase in the operation pressure (<0.9 MPa). The pore structure analysis of the char indicated that the micro-, meso-, and macropores were plugged after the tar-reforming reaction. A reaction model was proposed considering the pore plugging of the additional char to explain the experimental results. The results of the model fitting indicated that the amount of pore available for tar reforming decreased with the increase in the operation pressure. The model also suggested that the kinetic constant and residence time are more effective in increasing the conversion of tar than the amount of the available pore.

Variation of reaction heat of cedar wood pyrolysis with the variation of product distribution was estimated by means of heat balance calculation. For estimating the reaction heat of pyrolysis, heat balance was calculated with heating values of gas products, oil and char. Heating values of char and oil, except for gas product, were estimated with an estimation equation using only elemental composition of the products. The above heat balance indicated that the reaction heat of pyrolysis distributed in a wide range from −0.5 to 1.5MJ/kg with the variation of product yields. The thermal decomposition of char and oil vapor to permanent gas during pyrolysis contributes to the endothermicity of reaction heat, while the production of the oil vapor from cedar pyrolysis contributes to the exothermicity of reaction heat. The gas composition also affects reaction heat distribution. Decrease in CO yield results in exothermicity of reaction heat. Increase in CH4 contributes to exothermicity of reaction heat.

For the biomass-to-liquid (BTL) process, pressurized gasification is an option in order to produce synthesis gas. Fixed bed gasification is promising as it results in relatively high conversion efficiencies as compared to other types of gasifiers on a smaller scale. Wood chips are adaptable feedstock for updraft fixed bed gasifiers. In considering whether to use waste materials or the use of powders for gasifiers, adaptability of the feedstock is a concern. For this study, a pressurized updraft fixed bed gasifier was chosen. The experimental setup comprised the gasifier, feedstock hopper, feeder, etc. inside a pressure vessel. Palm kernel shells (PKS) and wood pellets were used as feedstocks in this study. Although PKS is as adaptable feedstock as wood chips for updraft gasifiers, the adaptability of wood pellets, which are a kind of briquette biomass, has not been confirmed. As a result, good gasification was achieved with PKS, whereas problems such as channeling of the gas flow were caused using wood pellets. Such problems were reduced by lowering the bed height of the materials inside the gasifier, which increased the outlet gas temperature.

Estimation equations for determining the heating value of hydrocarbon fuels were evaluated. Several types of estimation equations were proposed so far to determine the heating value on the basis of the elemental composition. The estimation equations were used to evaluate the elemental composition and the heating value of 406 standard gaseous organic compounds. As a result of the evaluation, Dulong's formula was appropriate for estimating the heating value; however, only a limited range of heating values can be determined, because Dulong's formula was developed for determining heating value of coals, which have unidentified structures. Another reason for the limitation was that the effect of latent heat. Therefore, Dulong's formula were modified with the lower heating values (LHV) of 406 standard gaseous organic compounds, which have identified structures, to obtain the following modified formula taking latent heat into account:

Pyrolysis bio-oil is a promising source of liquid fuels, but requires upgrading to remove excess oxygen and produce a satisfactory fuel oil. Nickel phosphide has been shown to be an active composition for hydrodeoxygenation (HDO) of bio-oil model compounds. In this study, nickel phosphide catalysts were used for direct upgrading of an actual pyrolysis bio-oil derived from cedar chips. The activity of Ni2P deposited on an amorphous SiO2 support for HDO was first verified using the model compound, 2-methyltetrahydrofuran (2-MTHF), at the temperature of the pyrolysis oil treatment of 350 degrees C. The Ni2P/SiO2 catalyst showed high activity for 2-MTHF hydrodeoxygenation under atmospheric pressure hydrogen with low cracking activity.Fast pyrolysis and catalytic upgrading were conducted sequentially using a laboratory-scale, two-stage system consisting of a fluidized bed pyrolyzer and a fluidized bed catalytic reactor both operating at 0.1 MPa, with a hydrogen partial pressure of 0.06 MPa. It was found that the Ni2P/SiO2 catalyst was moderately effective in upgrading the biomass pyrolysis vapors and producing a refined bio-oil with decreased oxygen content. The moderate deoxygenation of the bio-oil was confirmed by elemental analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the treated bio-oil mainly consisted of phenolic compounds, and the MS spectra before and after upgrading suggested that reactions including hydrodeoxygenation, hydrogenation, decarbonylation, and hydrolysis occurred during the upgrading. Furthermore, Ni2P supported on ZSM-5 zeolite eliminated oxygen in the bio-oil with smaller reduction in the oil yield than Ni2P supported on SiO2. The deoxygenation activity of the nickel phosphide catalysts was higher than that of conventional catalysts such as Ni/SiO2, Pd/C and an FCC-catalyst. (C) 2015 Elsevier Inc. All rights reserved.

This paper examined possibility of reduction and/or reforming of tar emitted during gasification of low rank coal in low-temperature gasification. During low temperature gasification, large amount of tar emitted and then interact with carbonaceous solid residue, i.e., char. This interaction is called as volatile-char interaction (VCI), and VCI results in inhibition of char gasification. Therefore, it is important to examine effect of operating conditions on VCI in continuous reactor. In the present study, we developed a circulating fluidized bed reactor that consisted of pyrolyzer and combustor. Coal was fed in the pyrolyzer and then volatiles including tar and inorganic gas etc. and char were formed. The char and silica sand bed material were transported to the combustor to be partially combusted. It means that char was recycled to the pyrolyzer and then contacted with tar in the pyrolyzer. In our previous study, we reported reduction of heavy tar and light tar when coal was fed onto the bubbling bed (top feeding). On the contrary to the previous study, we fed coal into pyrolyzer at the bottom of the bubbling bed. The heavy tar and light tar yield decreased in comparison with the top feeding condition, because tar vapor could be cracked in the bed (secondary cracking). Furthermore, we applied Kendrick mass diagram method that was frequently used in analysis of heavy oil to detailed analysis of heavy tar. According to the Kendrick mass diagram method it was found that deoxygenation was enhanced during char recycling in the bottom feeding condition.

Partial hydrodeoxygenation (HDO) of bio-oil derived from the pyrolysis of lignin can yield higher value added products, such as phenol derivatives. The HDO of 2-methoxyphenol (guaiacol) was studied over nickel phosphide (Ni2P) supported on various acidic substrates. The substrates were the microporous zeolite ZSM-5, a fluidized catalytic cracking (FCC) support consisting of USY zeolite embedded in a silica–alumina matrix, and an amorphous silica–alumina (ASA) material. Guaiacol was used as reactant because it is a good model compound for species derived from the lignin portion of biomass. The order of activity was Ni2P/ASA > Ni2P/FCC > Ni2P/ZSM-5. Contact time measurements indicated that the main pathway on Ni2P/ASA, the most active catalyst, was conversion of guaiacol to the primary intermediate catechol, which was then dehydroxylated to phenol.

Monolith SCR catalysts coated with V2O5-WO3/TiO2 were prepared by varying binder and coating thickness. Comparing with a monolith extruded with 100% V2O5-WO3/TiO2 powder, a coated monolith with a catalyst-coating layer of 260 µm in thickness exhibited the similar initial NO x reduction activity at 250°C. After 4 h abrasion (attrition) in an air stream containing 300 g·m–3 fine sands (50–100 µm) at a superficial gas velocity of 10 m·s–1, the catalyst still has the activity as a 100% molded monolith does in a 24-h activity test and it retains about 92% of its initial activity at 250°C. Estimation of the equivalent durable hours at a fly ash concentration of 1.0 g·m–3 in flue gas and a gas velocity of 5 m·s–1 demonstrated that this coated monolith catalyst is capable of resisting abrasion for 13 months without losing more than 8% of its initial activity. The result suggests the great potential of the coated monolith for application to de-NO x of flue gases with low fly ash concentrations from, such as glass and ceramics manufacturing processes.

The effects of H-2 concentration on the performance of a three-layer bed of Mo/HZSM-5 catalyst in nonoxidative methane dehydroaromatization at 1073 K and the distribution of coke formed along the bed were investigated systematically. Stepwise increasing the H-2 concentration up to 30% causes stepwise increases in C2H4 selectivity, while having little influence on benzene selectivity. Simultaneously, it also narrows the coke distribution by suppressing the formation of aromatic-type coke inside the zeolite channels and that of graphite-like C on the zeolite surface. The performance and coke distributions of one- and two-layer beds, together with the results obtained over the three-layer bed, showed that the cracking of C2H4 is more likely to dominate the coking process than the polycondensation of formed aromatics. Estimates of C2H4 approach to equilibrium for the reaction CH4 -> 1/2C(2)H(4) + H-2 confirmed that C2H4 always attains its equilibrium concentrations to ensure its availability for cracking. (C) 2015 Elsevier Inc. All rights reserved.

An integrated coal-gasification combined-cycle (IGCC) power plant, which represents the most environmentally friendly coal-fired power generation technology, has been developed and its efficiency is higher than that of conventional coal-fired power plants. More recently, an advanced-type integrated coal-gasification combined-cycle system (A-IGCC) was proposed[1,2]. The A-IGCC system can drastically improve the thermal efficiency; as a result, its overall efficiency is theoretically higher than that of a conventional IGCC system. In the A-IGCC system, coal is gasified at a relatively low temperature (<1173 K) using only the steam generated by the exhaust heat of the GT. The design of the reactor for low-temperature steam gasification of coal is essential for development of the A-IGCC system. In the present study, a new pyrolyzer-separated circulating fluidized-bed gasification reactor was developed. Coal is continuously pyrolyzed in the downer and the resultant char is sent to the bubbling bed gasifier for steam gasification while evacuation of the volatiles avoids the charvolatile interactions. Any ungasified char is transferred from the gasifier to the bubbling bed combustor, where it is either completely combusted or partially combusted and then recycled to the downer. Steam gasification was successfully performed in the absence of pyrolysis-derived volatiles, which strongly inhibit gasification. The recycling of the partially combusted char greatly increased its concentration in the downer thereby enhancing the reforming of the volatiles, in particular that of tar over that of char, and the resultant gas formation. The total yield of gases from the downer and bubbling bed gasifier was 45% higher than that obtained under direct feeding of the coal into the bubbling bed gasifier and full combustion of the char, i.e., with steam gasification of char in the presence of volatiles and subsequent reforming over char at a much lower concentration.

Experimental investigation on the lifetime performance and coking behavior of a 6 wt% Mo/HZSM-5 catalyst in the non-oxidative methane dehydroaromatization was conducted in a three layers fixed-bed mode and at 1073 K and a space velocity of 5000 mL/g/h. Characterization of the coke in all spent samples recovered after different periods of the reaction was performed using TG, XPS and TPO techniques. The time-dependence of the catalytic performance revealed that the test catalyst undergoes three stages deactivation over its lifetime, the benzene selectivity remains high and constant in the second deactivation stage and then decreases very rapidly from 64 to 18% in the last stage, and the C2H4 formation rate keeps increasing in a wide region covering the whole second stage and the first one third of the last stage. On the other hand, quantification of the coke contents of the spent samples and their characterization revealed that the average coke formation rate in the last deactivation is obviously higher than that recorded over the second stage and the formation of the aromatic type of coke inside the zeolite channels is primarily accelerated in the last stage. Thus, both observations together lead to a conclusion that C2H4, which has a smaller molecular diameter than benzene and is allowed to form inside the narrowed zeolite channels, is the main source of coke formation in the last stage of catalyst deactivation. C2H4 has been well recognized to form throughout the whole course of the reaction, and therefore the present observations are expected to provide a clue to exploration of the pathway that dominates the coke formation in the period of the benzene selectivity remaining constant (the second stage of catalyst deactivation) as well. (C) 2014 Elsevier B.V. All rights reserved.

The catalytic stabilities of Fe-modified and -unmodified 5% Mo/HZSM-5 catalysts in non-oxidative methane dehydroaromatization were compared at 1073 K and three reaction/H-2-regeneration cycle periods: 5 min CH4-5 min H-2, 5 min CH4-10 min H-2, and 5 min CH4-20 min H-2. Fe addition proved capable of remarkably increasing the catalyst stability over the cycles of 5 min CH4-20 min H-2 but was hardly effective over the cycles of 5 min CH4-5 min H-2. On the other hand, SEM observation of all spent samples revealed that Fe addition causes a massive accumulation of carbon nanotubes under the latter cyclic condition but little in the former. Thus several sets of comparative tests were specially designed and performed to gain an insight into the role of Fe-catalyzed cyclic formation of carbon nanotubes in stabilizing the activity under the cyclic condition of 5 min CH4-20 min H-2. The results further confirmed that at this condition, cyclic formation of carbon nanotubes enhances cyclic evolution of H-2 and increases the H-2 concentration of the system, which is thermodynamically beneficial for suppression of formation of the activity-deactivating surface coke. Finally, it was further confirmed that at least a 20 min H-2 exposure is required to remove most of the carbon nanotubes and surface coke formed during a 5 min CH4 exposure and reactivate most of the Fe nanoparticles and make them available again for formation of catalytic carbon nanotubes with an enhanced H-2 evolution, i.e., with a controlled formation of the surface coke in the next CH4 exposure.

Estimation method for thermodynamic properties of organics in liquid fuel are proposed in this work. Especially this method can be applied to bio-oil produced from biomass pyrolysis. Thermodynamic properties of more than 600 compounds, which can be obtained in NIST chemistry webbook, were investigated for the estimation of thermodynamic properties. Simple estimation methods for the heat capacity and heating value are successfully provided with only the elemental composition of unknown compounds.

Annual production of sewage sludge in Japan has increased, and most of the sewage sludge is incinerated. With conventional sewage sludge incinerators, a large amount of energy is needed for operation. Additionally, the emissions of greenhouse gas N2O are expected to be high, because sludge contains a high concentration of nitrogen. In this R&D, an advanced sewage sludge incinerator “turbocharged fluidized bed incinerator,” which can achieve not only energy savings but also a low environmental impact, was proposed in collaboration with Public Works Research Institute and companies. This new system consists of a pressurized fluidized bed combustor coupled with a turbocharger. The R&D to achieve practical use of the proposed system is primarily explained in this paper.

A new type of circulating fluidized bed gasifier, which is called a fluidized bed gasifier with triple-beds and dual circulation, was proposed. Main features are the adoption of a triple-beds structure, the separation of circulation paths for tar-absorbing particle and fuel. Pyrolyzer and gasifier each have a two-stage fluidized bed. Tar can be processed in the gasifier. The two circulation systems each have an independent combustor. The purpose of this study is to evaluate the gasification characteristics of woody biomass by bed material in a fluidized bed gasifier. The bed material used porous alumina and limestone. As a result, the reforming of tar of porous alumina is much higher than that of limestone. Therefore, the porous alumina, which can process the tar in a fluidized bed gasifier, is suitable for the bed material. Additionally, the amount of tar absorbed by porous alumina was elucidated by the gasification experiment through which particles circulate continuously. The tar was generated because the fuel was supplied on the porous alumina particle bed. It is predicted that the amount of tar absorbed by porous alumina is more improved in a practical gasifier because the contact efficiency between the porous alumina and the tar in the proposed gasifier is much higher than that of this experimental condition.

In the present study, we attempted to reduce tar emitted during pyrolysis of coal by utilizing char-volatiles interaction (CVI) phenomena in a circulating fluidized bed (CFB) reactor. The CFB reactor is consisted of bubbling-bed pyrolyzer and combustor made of quartz, therefore, behavior of solids can be directly observed. Coal was fed in the pyrolyzer at the temperature range from 550 to 900℃ and then pyrolyzed to from volatiles including gas and tar. Product gas from the pyrolyzer was analyzed by GC, and light/heavy tar was collected by traps and then analyzed. Resultant char was circulated to the combustor at 850℃ to be partially combusted. Un-burnt char particles were circulated to the pyrolyzer. That is, char is recycled to the pyrolyzer. In other words, CVI would be enhanced by the char recycling. The product gases, especially, H_2 and CO were increased by the char recycling. On the other hand, light tar such as benzene, naphthalene etc. was decreased, and heavy tar was also decreased by the char recycling.

An in situ bio-oil upgrading process employing two circulating fluidized beds (CFBs) in series is proposed. One CFB allows the rapid pyrolysis of biomass and the other CFB facilitates bio-oil upgrading in the presence of a catalyst. In bio-oil upgrading CFBs, bio-oil is deoxygenated with hydrogen which is known as the hydrodeoxygenation (HDO) process. A system analysis was carried out on this process with respect to heat and mass balance to optimize the process efficiency and operating conditions. The product distribution of the pyrolysis CFB was experimentally obtained using a fluidized-bed reactor. According to the experimental results, a pyrolysis temperature of 823 K produced the highest bio-oil yield of 66 mass%. Based on the analysis of the bio-oil upgrading process, the maximum energy conversion from biomass to bio-oil was determined to be as high as 70% with respect to the biomass lower heating value (LHV). The energy conversion was strongly affected by the amount of hydrogen that was introduced to the bio-oil upgrading CFB. The bio-oil upgrading CFB produced a large amount of heat owing to the exothermic reaction of the HDO process. Heat elimination from the bio-oil upgrading CFB was required to maintain the catalyst temperature. It was found that the thermal utilization of unreacted hydrogen and an increased bio-oil yield during pyrolysis are required to further improve the energy conversion.