Atsushi Inaba

Fluid Catalytic Cracking of Coal Liquids (Part 2)

石炭液化油中質油留分の流動接触分解反応についてナフサおよび中質成分の収率ならびにコーク生成量に与える予備水素化処理の効果を実験的に検討した。試料としたカナダ産バトルリバー炭からの液化油中質油留分の水素化処理は, 通常の固定床流通反応装置によってNi-Mo/Al2O3触媒を用いて反応温度370°CおよびLHSV 1h-1の条件で水素圧を50, 100ならびに150kg/cm2•Gと変化させて行った。水素化処理油のH/C原子比は水素圧が高くなるに従って上昇し, 芳香族化合物の環水素化反応も前報で取り上げた重質油留分の場合よりも一層効果的に進行した。次に, 得られた水素化処理油について, ASTMに準じて設計された小型試験装置によって, スチーミング処理済のFCC触媒を使用して反応温度482°CおよびWHSV 16wt/wt/hの条件で接触分解反応を行った。予備水素化処理によって接触分解によるコーク生成量は1.3wt%まで減少し, また中質油留分の蒸留性状は大きく変化し, ナフサ成分の収率が2.5～5倍まで上昇するなど予備水素化処理を組み合わせることによって効果的に軽質化できることがわかった。また, 石炭液化油中に含まれているn-パラフィンならびに一環から三環までのシクロパラフィン, 部分水素化芳香族および芳香族化合物の中から主なものをモデル試料として選び, 接触分解反応を行って各々の化合物タイプによる反応性を検討した。

Fundamental study of the effect of hydrogen donor solvent on coal liquefaction

Abstract To evaluate the hydrogen donating ability of solvent for coal liquefaction, the liquefactions of Taiheiyo coal (Japanese subbituminous coal) and Yallourn coal (Australian brown coal) have been carried out in a 500 ml autoclave at 430–450°C under high pressure of hydrogen or nitrogen using a red mud—sulfur catalyst in the presence of different kinds of hydrogen donor solvents such as tetralin, decalin, methyl substituted tetralins and naphthalenes, etc. Liquefactions of Taiheiyo coal and Yallourn coal using hydrogen donor solvents such as tetralin or methyl substituted tetralins showed higher conversion and yield of SRC than that obtained using decalin. On the other hand, to estimate the effect of the hydrogen donor solvent, ab initio SCF molecular orbital calculation for several solvent molecules, such as tetralin, decalin, naphthalene and their methyl substituted homologues, has been applied. Calculated reactivity indices, for example, frontier electron density of hydrogen atoms in the solvent molecule and atomic orbital bond population of Cue5f8H bond, were discussed and compared with the experimental results.

Two stage liquefaction using bottom recycle. (I). The effect of hydrogenation catalyst at the first stage.

To investigate the feasibility of nondistillable bottom recycle for the enhancement of liquid yields, two stage liquefaction of Yallourn and Taiheiyo coals were conducted using NiMo/Al2O3 with red mud at the first stage.Over successive passes, high coal conversion (>96wt%) at the first stage was maintained, and yields of gas and THFI were not increased. It was also indicated that 60wt% of both coals were converted to cyclohexane solubles at the initial stage accompanied with the promoted conversion of coal and/or cyclohexane insolubles. The improvement of conversion and product selectivity seems to be related with the changes in quality of recycle solvent in terms of the efficiency of hydrogen transfer reaction, and with the removal of hetero compounds causing the regressive reaction.The above results suggest the possibility of highly efficient conversion of organics inherent in both brown and subbituminous coals to liquid products.