Economical process of coal liquefaction is urgently needed in these days. Only Aoji process was successfully and economically operated in 1943. I improved the Aoji process and developed a tubular plug flow process named ‘M-coal’ process. The ‘M-coal’ reactor is an efficient direct liquefaction reactor characterized with (1) heterogeneous inner heating, (2) multiple tower with multiple H2 supply, (3) tubular plug flow and (4) inexpensive construction cost. The ‘M-coal’ process is expected to be realized as soon as possible.
The present review is mainly concerned with the study on the coal structure using solid state NMR, especially for the relationship between relaxation times and coal dynamic structures. The reports on the measurement of T1H (spin-lattice relaxation time) and T2H (spin-spin relaxation time) of coal were mainly reviewed. These two parameters directly relate to the molecular mobility. Thus the measurement of these relaxation times could make an investigation for coal molecular mobility. The influence of water existing in coals and the swelling of coals derived by organic solvents to the relaxation time and the changes of the coal molecular mobility by heating were also studied. More information on the chemical structure of coal and the structural changes of coal during various reactions could be obtained in the basis of molecular mobility using solid state NMR.
Methodology for evaluation of the environmental impacts of emissions, energy conservation and resource depletion in Life Cycle Assessment (LCA) are reviewed in this paper. Currently, the environmental impacts are evaluated by the classification, such as “Greenhouse effect” and “Ozone layer depletion”, and aggregation method, whose value are calculated by the product of the emissions volume/mass and the weighing factors. The weighing factors are presently estimated based on scientific knowledge as far as possible. In order to evaluate environmental impacts on the different classifications in the same unit, the method of the calculation of environmental costs has been the focus of attention recently. In the future, we should consider not only environmental costs caused by the emissions but also other costs such as resource depletion and energy conservation.
Understanding the behavior of sulfur capture reaction in boiler is very important for coal gasification and combustion which used injection desulfurization. In this review, the knowledges which have been accumulated during the past 30years on sulfur capture reaction and reaction rate are surveyed. Limestone and Dolomite are the most widely used sorbents as well as in fully or partially calcined conditions, and there are about 15 principal reactions occurring between these sorbents and the gaseous reactants H2S, COS, SO2, H2O and CO2. The major parameters that influnce tese reactions are sorbent type, particle size, temperature, pressure and gas atmosphere. Closure of pores is found to be a main reason for lowering the reactivity of the sorbent. On the other hand, gas atmosphere has the effect not only on reaction rate but also on the sintering of the solid reactant and product.
For CO2 removal from flue gases containing SO2 at thermal power plants, secondary alkanolamine with high molecular weight (abb. HIA) was selected as an absorbent because of low utility consumption. SO2 forms sulfite salt in absorbent and it is oxidized with O2 to form the sulfate. These salts called Heat Stable Salts (HSS) reduce CO2 removal ratio. On the other hand, the sulfite consumes O2 in the absorbent and the resistance to oxidation of HIA can be expected. We estimated the relationship between concentration of HSS and CO2 removal ratio, and the resistance to oxidation of HIA absorbent by the presence of SO2 in treated gas. Based on these results, pilot testing (flue gas capacity: 1, 000 Nm3/h, CO2 removal ratio: 90%) was carried using coal oil mixture-fired power plant flue gas for continuous 2, 000 hours (accumulating time of 2, 441 h) to evaluate the resistance to oxidation and regeneration heat of HIA. Oxalic acid by oxidative degradation was accumulated 0.0095% after completion of pilot testing, and its amount was 0.1 times as low as that of LNG-fired flue gas. Furthermore, four kinds of cyclic amines were detected by GC-MS analyses and three of them were compounds by oxidative degradation. Their amounts of the mixture were spectrophotometrically determined to be 0.19% based on a reasonable assumption of the average molar absorptivity of the mixture. Average oxidation rate of the mixture was estimated 8.8x10-5%/h. This was 0.4% of the total loss of HIA. Regeneration heat of HIA was 20% as low as that of the conventional absorbent even in the case of accumulation of HSS up to 2% as the reduced concentration of H2SO4.
Supercritical water extraction of Japanese sub-bituminous (Taiheiyo) coal was conducted with semi-batch type reactor (380°C, 25-40 MPa) and the results were compared with that for supercritical toluene extraction (380°C, 15-30 MPa). Higher coal conversion (55wt%) and liquid yield (45wt%) were obtained for supercritical water extraction, and this is found to be because of (1) the inhibition of polymerization or recombination of the primary products of thermal decomposition of coal and possibly due to the radical quenching with H or OH, and (2) the hydrolysis of ether or ester bond in coal.
NOx removal in diesel exhaust using selective catalytic reduction by methanol over alumina was investigated. Although a slight decrease in catalytic activity took place at the initial stage of the evaluation, a stable NOx conversion observed over a conventional honeycomb alumina for more than 4, 000 hours. The deNOx performance enhanced on a honeycomb-type alumina manufactured from improved materials, and nearly 50% of steady NOx conversion was obtained under the conditions of SV=10, 000 h-1, temp.=400°C and CH3 OH/NOx mole ratio=ca. 2. The deNOx performance of alumina was independent of the composition of diesel exhaust gas changing with the engine load. Although a gradual increase of emission pressure occurred due to the paticulates in diesel exhaust, the pressure increase was negligibly small by using the honeycomb alumina controlled to the pich size of 3.3 mm. The unreacted methanol and formaldehyde which are intermediate of methanol could easily be oxidated to CO2 by using a small amount of Ptcatalyst even at the low temperature.