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Hydrodesulfurization (HDS) of atmospheric residue (AR) over Ni-Co-Mo catalysts supported on y-alumina was carried out to examine the effect of alumina pore size on HDS activity, hydrodemetallization (HDM) activity and initial catalyst deactivation under deep hydrodesulfurization conditions. HDM activity slightly increased with alumina pore size, but HDS activity decreased due to the decrease in the surface area of the support. Deactivation of the HDS catalyst was greater on large pore size supports than on medium pore size supports. The combination of HDS catalyst with large pore size supports (40%) and medium pore size supports (60%) did not improve the catalyst life. HDS was carried out with the large pore size support catalyst at the upstream side in the first reactor and the medium pore size support catalyst at the upstream side in another reactor. Catalyst deactivation was greater in the former than in the latter reactor. These results suggest that HDS catalyst supported on alumina with medium pore size has a higher performance than HDS catalyst supported on alumina with large pore size for deep HDS. To examine the behavior of asphaltene (ASP) at the reaction temperature, adsorption of ASP was investigated on catalyst supports with different pore size. ASP was a large molecule at low temperatures, but the molecular size decreased at HDS reaction temperature caused by the dissociation of the molecular structure. Furthermore, ASP containing sulfur was preferentially adsorbed on the catalyst support. The chemical interaction between ASP and alumina indicates that alumina is a good support for the HDS reaction.常圧残油の水素化脱硫反応HDSを細孔径の異なるγ-アルミナに担持したニッケル-コバルト-モリブデン触媒を用いて深度脱硫条件で常圧残油の反応を行い水素化脱硫HDS活性水素化脱メタルHDM活性および触媒活性劣化に及ぼす細孔径の影響を検討した。HDM活性は細孔径とともにわずかに増加したがHDS活性は細孔径とともに減少した。また大きな細孔径をもつ担体に担持した触媒の初期活性劣化は中位の細孔径をもつ触媒よりも大きくなった。大きな細孔径をもつHDS触媒40と中位の細孔径をもつHDS触媒60の組合せあるいは二つの触媒の充填順序を変えて反応を行ったが組合せによる触媒寿命の延長効果は小さく特に大きな細孔をもつ触媒を上流側に配置すると触媒寿命は短くなった。アスファルテンASPを多く含む重質な深度脱硫操作に対しては中位の細孔径をもつ触媒がすぐれた性能を発揮することが分かった。これらの結果を説明する目的で反応温度付近におけるASPの触媒担体への吸着実験を行った。ASPの吸着量は低温では細孔径とともに増加したが温度の上昇に従い細孔径による吸着量の差が小さくなった。すなわちASP分子は高温になるとミセルの状態を解いて比較的小さな分子になった。さらに硫黄を含むASPは触媒担体に吸着しやすい性質をもつことが分かった。このような化学的相互作用によりアルミナはHDS触媒の担体として高性能を示すと考えられる

Effects of Asphaltene Content in Atmospheric Residue and Mean Pore Size of Catalyst on Initial Deactivation of Hydrodesulfurization Catalyst