The NOx reduction activities of various supported silver catalysts were measured. Among the tested catalysts, Ag/Al2O3 showed the highest activity. Though Ag/ferrierite showed rather higher activities at low temperatures, the activities were almost the same with that of ferrierite itself. Other catalysts had lower activities. Reactivities of hydrocarbons had large effect on the NOx reduction over the Ag/Al2O3 catalyst at low temperatures. Hydrocarbons which have longer chain were liable to react at lower temperatures and were able to reduce NOx more effectively. Unsaturated hydrocarbons showed higher reactivity and gave higher NOx reduction rate than saturated ones. The effects of contact time and the concentrations of inlet NO, propene, oxygen, and water vapor on the reduction of NOx over the Ag/Al2O3 catalyst were also investigated. The reduction rate of NOx below 450°C was greatly decreased with the decrease of contact time. The reduction of NOx was promoted at higher propene/NO ratios. At constant propene/NO ratio, the proportion of propene which was used for NOx reduction increased with the increase of concentrations of propene and NO.The consumption of propene by oxygen was accelerated at high concentrations of oxygen. The effect of water vapor was large at low temperatures a small amount of water inhibited the reaction of propene and decreased the reduction rate of NOx significantly below 400°C.
Hydrotreatment of Yallourn coal liquid (b .p.180-240°C) was carried out using Co-Mo/Al2O3 and Ni-Mo/Al2O3 catalysts in a fixed bed flow reactor. Principal components in the feedstock are alkyl-phenols (34 .4wt%), alkyl-tetralins (23.8 wt%) and alkyl-naphthalenes (17.7wt%) and paraffins (9.8wt%) of carbon numbers from 8 to 17. Deoxygenation of phenol derivatives proceeds effectively with increasing a reaction temperature, a contact time and a hydrogen pressure . Products are substituted benzenes and cyclohexanes. Larger amounts of substituted cyclohexanes were obtained with Ni-Mo catalyst, indicating higher capability of hydrogenation of this catalyst. Alkyl-naphthalenes decreased with increasing severity of the reaction conditions, promoting dealkylation and hydrogenation reaction. Alkyl-tetralins increased slightly with an increase in the reaction temperature due to the hydrogenation of naphthalenes, and then decreased at 400°C to give alkyl-benzenes . In the temperature range of 280°C to 360°C deoxygenation of phenols proceeded more effectively with the Co-Mo catalyst, and hydrogenation of aromatic rings effectively occurred with Ni-Mo catalyst.
The CO2 gasification behavior of Ca-loaded Yallourn brown coal char was investigated in the presence of H2 or CO with a thermal balance . The chemical form of Ca catalyst was in situ analyzed with a high temperature X-ray diffraction. In addition, oxygen containing-compounds on Ca-loaded char were evaluated with transient kinetics and temperature programmed desorption techniques. On the basis of these results, the mechanisms of H2 and CO inhibition on Ca-catalyzed carbon gasification were discussed. It was found that the presence of H2 suppresses the formation of surface oxygen containing-compounds as reaction intermediate. Therefore, H2 inhibition can be attributed mainly to the adsorption of H2 an Ca catalyst or on carbon surface in contact with Ca catalyst. As a result, the following catalytic processes are disturbed; the adsorption of CO2 on Ca catalyst, and the formation of CaCO3-C complexes. The temperature dependence of CO inhibition was quite different form the case of H2 inhibition, and this implies that the mechanism may be different in the two inhibition cases.
Ge/C composites could be prepared by the polycondensation of anthracene with GeI4 at 400°C, followed by the high temperature treatments of polycondensed products from 750 to 3000°C. The lubricative properties of Ge/C composites formed were studied by measurement of friction factor, based on finding of their soft nature at time of pulverization. The friction of carbonized and graphitized Ge/C composites was found to decrease with the development of lamellar structure of the parent carbon materials. Nevertheless, Ge/C composites, prepared at even a lower temperature range from 1200 to 1500°C, showed small friction factors which were similar to those of graphite materials. This was considered to be due to the formation of composites with Ge.