Effects of molten tin catalyst on coal conversion in a hydrogen donor solvent

Abstract

Catalytic activity of molten tin for the liquefaction of Shin-yubari coal in tetralin solvent was investigated. The catalyst promoted the coal conversion when a small amount of donor solvent was used, while almost no catalytic effect was seen when a large excess of solvent was used. Among conversion data, those for asphaltenes showed most peculiar behavior when plotted against the solvent/coal ratio; a higher and almost constant conversion value was observed for the reaction over molten tin catalyst, while it was strongly dependent upon solvent/coal ratio in the non-catalytic reaction. The effects of reaction temperature on coal conversion with and without molten tin catalyst were also studied using a small amount of solvent. In the non-catalytic reaction the conversion to asphaltenes exhibited a maximum at around 420°C, suggesting that repolymerization of coal fragments became predominant at high temperatures. The temperature for the maximum asphaltene conversion raised to 440°C in the catalytic reaction, showing a radical stabilizing effect of this catalyst. The catalytic behavior of molten tin was also discussed in the light of kinetic analysis.