Characteristics Of Catalytic-hydrogenation In Direct Shenhua Coal Liquefaction

Direct coal liquefaction (DCL) is an advanced clean coal technology. A major limitation to know the real process of coal liquefaction is fairly complicated coal structure and its variable physical and chemical properties. The purpose of this paper is to understand the characteristics and mechanism of catalytic-hydrogenation in direct coal liquefaction.A25ml tubing bomb reactor was designed as well as ancillary facilities consisting of inflatable device, sand bath furnace and Soxhlet extraction system. The apparatus had better properties to meet the requirements of DCL experiments.Orthogonal experiment was adopted to explore the effect of catalyst, temperatue, initial pressure and reaction time during the Shenhua(SH) DCL. The high oil yield is62.40%. The major factor on the oil yield is in the order of reaction time> initial pressure>temperature> catalyst. The condition of appropriate liquefaction technology is:SH catalyst1%(Fe, wt.%), the ratio of THN/coal2:1,60min,445℃and90Hz.The effect of catalyst on the SH DCL was investigated. The results show SH catalyst has higher catalytic activity than pyrite in liquefaction. The interaction between pyrite and coal not only reduces the decomposition temperature of pyrite but also promots the hydrogenation reaction of coal liquefaction. The activity of intermedium H2S, produced by H2reacting with S generated in pyrolysis of pyrite, was a major contributor to hydrogen transfer from gas to liquefaction products. H2S directly added to process has little influence on hydrogen transfer.The impact of H2S on the hydrogen-transfer in SH DCL was studied. It is found that there has little effect on DCL when H2S partial pressure was less than1%. Oil yield increases then decreases with increasing the partial pressure of H2S, and reaches the maximum49.95%at volume content of3%,5.23%higher than that without H2S. Higher initial pressure results in high solubility of H2S in solvent, which could accelerate the rate of hydrogen-transfer from gas to coal. As a result, oil yield increases by9.26%from7MPa to8MPa. The positive mechanism of H2S was related to catalyst and liquefaction solvent in reaction.