Koichi Matsuoka

Reaction of NO with soot over Pt-loaded catalyst in the presence of oxygen

Abstract NO x and particulate matter are the main environmental hazards in the diesel exhaust. In order to explore a suitable method to remove NO X as well as particulate matter, we have examined the catalytic reduction of NO X with soot in the presence of oxygen. Pt catalyst loaded on Al 2 O 3 -coated honeycomb was found to be more active than K, Ca and Cu catalysts. Even in the presence of 8% O 2 , NO can be reduced to N 2 by soot with Pt catalyst. NO was completely converted to N 2 in the isothermal reaction at 500°C, and the high activity of the catalyst retained for a long time period. The effects of Pt catalyst and O 2 on the mechanism of C-NO reaction was examined by using step response experiment.

Simple Continuous High‐Pressure Hydrogen Production and Separation System from Formic Acid under Mild Temperatures

A simple and continuous high‐pressure (>120 MPa) hydrogen production system was developed by the selective decomposition of formic acid at 80 °C using an iridium complex as a catalyst, with a view to its application in future hydrogen fuel filling stations. The system is devoid of any compressing system. The described method can provide high‐pressure H2 with 85 % purity after applying an effective gas–liquid separation process to separate the generated gas obtained from the decomposition of formic acid (H2/CO2=1:1). The efficiency of the catalyst lies with its high turnover frequency (1800 h−1 at 40 MPa) to produce high‐pressure H2 with a good lifetime of >40 h. Interestingly, only very low levels carbon monoxide (less than 6 vol ppm) were detected in the generated gas, even at 120 MPa.

Mode of occurrence of calcium in various coals

Abstract Calcium in coal can be classified into two parts: mineral matter and cationic metals associated with organic matrix. Chemical leaching with aqueous ammonium acetate (NH 4 OAc) solution has been widely used for the purpose of removing only ion-exchanged metals. However, it still remains uncertain whether the leaching can remove only these metals, because the leaching experiments have been mainly carried out using low rank coals. In this study, the leaching of three Argonne premium coals was carried out under different conditions to examine the effect of operating variables on leaching, and furthermore the species leached out were identified. Calcium leaching of Pocahontas #3 (POC) coal by aqueous NH 4 OAc solution was examined in detail. Under our standard condition, the leaching yield was 80%, almost the same as for aqueous HCl leaching. Furthermore, we analyzed the mineral matter in the three coals before and after the NH 4 OAc leaching by X-ray diffraction analysis (XRD) and computer controlled scanning electron microscopy (CCSEM). According to the results from XRD and CCSEM, it was found that a substantial portion of calcite was removed by the NH 4 OAc leaching. In conclusion, not only ion-exchanged calcium but also calcite was leached out with NH 4 OAc solution.

Mechanism of N2 formation during coal char oxidation

In spite of many studies, the reaction mechanism of the evolution of nitrogen-containing gases during coal oxidation is not fully understood yet. One reason is that the nitrogen mass balance has not been well established in most studies. In the present study, we attempted to clarify the N 2 formation mechanism during the reaction between coal char and O 2 by paying special attention to nitrogen mass balance. The closure of the nitrogen mass balance was 100±6%. Blair Athol coal char was used as a sample, and the formation of N-containing species was determined during temperature-programmed reaction as well as isothermal reactions at 700 and 850°C in a packed-bed reactor. In all the cases, N 2 was the major product, with a little amount of NO as a minor product. Under the isothermal reaction conditions, the ratio of NO/N 2 was low in the initial stage and increased in the later stage. The effect of bed height on the product gas distribution was examined, and it was found that the shallower the bed, the higher the ratio of NO/N 2 . When the O 2 /He gas mixture was switched to He, the formation of N 2 and NO became almost negligible. From these observations, we proposed the following reaction mechanism for the N 2 formation: the formation of NO as a primary oxidation product, and the reaction of NO with surface nitrogen species to form N 2 . The NO capture on carbon surface to form surface nitrogen species is thought to be an important step during the course of this reaction.

Mg-modified ultra-stable Y type zeolite for the rapid catalytic co-pyrolysis of low-rank coal and biomass

To improve the quality of oil derived from the fast co-pyrolysis of low-rank coal with biomass, various metal-modified ultra-stable Y type (USY) zeolites are mixed with the samples for the co-pyrolysis process. It is found that Mg-modified USY zeolite shows high catalytic activity with high coking resistance ability in this study. A further treatment of Mg-modified USY zeolite by steaming process further improves the coke resistance and the catalytic activity toward production of more hydrocarbons in the pyrolytic oil. It is indicated that Al atoms in the original zeolite framework could be dislocated by the steam treatment and a new framework consisting of Al–Mg–Si could be formed on the outside of the zeolite framework, which is beneficial to change the physical and chemical properties of the zeolite and increase the catalytic activity and coke resistance ability in the process of rapid catalytic co-pyrolysis of low rank coal with biomass.

HCN and N2 formation mechanism during NO/char reaction

The reaction of phenol/formaldehyde, resin char with NO was carried out in the temperature raoge from 850 to 1100°C. Nitrogen-containing species formed during the reaction were carefully examinedby ahigh-speed gas chromatograph and a mass spectrometer. Large amounts of N 2 and CO and small amounts of CO 2 and N 2 O were formed by the NO/char reaction. In addition to these, products, a significant amount of HCN was observed in the high-temperature region. The mechanism of HCN formation behavior was examined by step response experiments. It was found that HCN was formed through nitrogen-containing surface species on char, C(N), and its formation rate was greatly affected by the amount of available hydrogen. The N 2 formation was also affected by the amount of available hydrogen in the following manner. N 2 was formed mainly by the reaction of C(N) with gaseous NO. However, a part of C(N), was consumed through the conversion to HCN if sufficient hydrogen was present in the vicinity of C(N). When the HCN formation took place, the amount of C(N) decreased, leading to less N 2 formation. Thus, it is suggested that even in the char-related reaction, hydrogen content is an important factor for the fate of nitrogen.

Ultrasonic loading of calcium on coal for enhanced SO2 captured

Abstract The mixture of coal and lime was ultrasonically hydrated to impregnate calcium onto coal. The calcium-loaded coal was combusted in a fixed bed reactor to examine the desulfurization effectiveness of calcium. The results showed that compared to the mechanical stirring, the ultrasonic treatment significantly improved the SO 2 removal, particularly at the Ca/S atomic ratios below 1.5. This is rationalized by the high dispersion of calcium on coal particles caused by the physical and chemical effects of ultrasonic irradiation.

Effects of Impurities Contained in Coal-Derived Syngas on the Performance of SOFCs

Power generation tests using a single-cell SOFC fueled by coal-derived syngas were conducted under a constant voltage of -0.8 V versus air (reference). The syngas was produced in the steam gasification of pulverized coal in a laboratory-scale fluidized-bed gasifier and was supplied to SOFC anode with different gas cleaning conditions: with/without filtrations and water washing. It was possible to generate the electrical current by the coal-derived syngas for several hours and we found that the degradation behavior of SOFC anode was notably affected by gas cleaning conditions. A SEM-EDX analysis confirmed that the micro-scale change in morphology of SOFC anode occurred due to the sintering of Ni particles over the anode layer, suggesting that eutectic melting of Ni might be enhanced by some impurities contained in the coal derived syngas.

Estimation of thermodynamic properties of liquid fuel from biomass pyrolysis

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.