Tsuneyuki Homma

Catalytic activity of physically-mixed nickel compounds on the CO2 gasification of phenol-formaldehyde resin char

Abstract In order to account for the various activities of different nickel compounds in low temperature catalytic gasification of carbon the reducibility of individual nickel compounds in carbon dioxide to metallic was studied by thermogravimetry and the behaviour of mixture of nickel salts with a phenol-nickel formaldehyde resin char was investigated by temperature-programmed X-ray diffraction analysis. A correlation was found between the order of reducibility of the nickel salts and their order of activity in catalytic gasification. Low temperature gasification up to 98 wt% was demonstrated for char mixed with nickel acetate (up to 9/10 wt% Ni), which suggests that there may be good prospects for finding a method of complete gasification with nickel.

Catalytic activities of ion-exchanged nickel and iron in low temperature hydrogasification of raw and modified birch chars

Abstract Raw, HNO3 oxidized and carboxymethylated birch woods loaded with nickel or iron by the ion-exchange method were carbonized at 500 °C in a flow of nitrogen, and the resulting chars were hydrogasified in a thermobalance to examine their reactivities below 700 °C. The amounts of ion-exchanged metals on raw char were too small to give high gasification reactivity. However, oxidized and carboxymethylated woods with increased ion-exchange capacity produced much more reactive chars. Both nickel and iron exhibited larger catalytic activities on carboxymethylated chars than on oxidized chars, because better metal dispersion could be achieved on carboxymethylated wood with its larger cation exchangeability. It was noteworthy that only 1 wt% loading of iron, as well as nickel, on carboxymethylated char was sufficient to attain a gasification of 90 wt% at 700 °C. It was also noted that the catalytic effect, up to 600 °C, of iron on the gasification of oxidized and carboxymethylated chars was larger than that of nickel. This is ascribed to two factors; greater catalytic activity of metallic iron formed during the gasification than that of nickel metal, and low ash level in the chars. Above 600 °C, however, serious loss of activity of the iron was observed in the absence of wood ash. This showed the different influence of wood ash on the catalysis of iron in the low and high temperature regions.

Contact between catalyst and carbon in the tin- and lead- catalyzed gasification of carbon with carbon dioxide

Abstract The wettability and distribution of tin and lead metals on a phenol-folmaldehyde resin char were investigated by means of contact angle measurement and microscopic analysis. The wettability on the pelletized char was not so significant. However, stannic oxide was found to be distributed around a tin catalyst particle. This can be considered a result of the vapor phase transport of stannous oxide and its oxidation by CO 2 . Stannous oxide was formed through a red-ox type catalysis cycle. On the other hand, in the case of lead-catalyzed gasification, the mobile species was the lead metal itself. Thus, the high catalytic activity of tin and lead metals was appropriately ascribed to an intimate contact between the catalyst and the carbon substrate caused by the vapor phase transportation of stannous oxide and lead metal.

A Thermal Analysis of Copper Sulfate Pentahydrate under Pressure

The effect of pressure on the thermal dehydration process of CuSO4, 5H2O has been investigated using thermobalance and DTA apparatus under nitrogen pressure in the range between 1 and 40 atm.On the dehydration of four moles of coordination water, two peaks appeared at 1 atm and only one peak appeared above 4 atm on the DTG curves and three endothermic peaks appeared on DTA curves. The peak positions of DTG curves and one of three peaks of DTA curves shifted to higher temperature with the increase of pressure. This shift of peaks was observed at similar temperature both DTG and DAT curves, and the tempature was approximately the boiling point of water under each pressure applied. No peaks were observed on DTG curve that corresponded to the two unshifted peaks on DTA curves.From examinations of these results, two unshifted peaks on DTA curves were attributed to the dissociation of coordination water and the shifted peaks on DTG and DTA curves to the evaporation of liquid water dissociated from the heated sample. The activation energies of these reactions were calculated by Kissingers method.