パラフィン系および中東系常圧残油の熟分解反応と留出生成物の水素化処理 Thermal Cracking of Paraffinic and Middle East Atmospheric Residues and Hydrotreatment of Distillate Products

流通式反応装置を用い，440～520 ℃，N₂ 0.2～0.8 MPaの反応条件下でパラフィン系常圧残油の熱分解反応を行い，生成物分布に及ぼす反応温度と圧力の影響を調べた。減圧残油分は480 ℃まで徐々に減少し，それ以上の温度ではほとんど消失した。それに伴い，全留出油とコークの収率は増加し，480 ℃以上ではほぼ一定となった。重質留出油の収率は480 ℃以上で増加したことから，軽質留出油の収率は480 ℃で最高となり，それ以上の温度では減少した。反応圧力が高いほど，重質留出油の収率が減少するとともに，軽質な留出油およびコークが増加した。二種類のパラフィン系常圧残油と二種類の中東産常圧残油を，480 ℃，N₂ 0.4 MPa，0.5 hの条件下で熱分解し，得られた生成物の組成や性状を互いに比較した。パラフィン系常圧残油の留出油（C₄～500 ℃）収率は約90 %と高かったが，中東系常圧残油では70～80 %と低かった。パラフィン系常圧残油から得られた留出油生成物の硫黄含量は，中東系に比べて非常に低かったが，窒素含量は両者で同程度であった。中質および重質留出油の水素化処理を行い，脱硫反応性，脱窒素反応性を調べたところ，パラフィン系では中東系に比べて脱硫速度が4～6倍大きかった。一方，脱窒素速度は，中質留出油では大きな差が見られなかったが，重質留出油ではパラフィン系原料油の方が小さかった。

Thermal cracking of paraffinic atmospheric residue (AR) was performed in a continuous-flow reactor under the reaction conditions of 440-520 °C and N₂ 0.2-0.8 MPa, and the effects of the reaction temperature and pressure on the product distribution were examined. The vacuum residue fraction gradually decreased up to 480 °C and almost disappeared at higher temperatures. Accordingly, the yields of total distillate and coke increased and became nearly constant over 480 °C. As the heavy distillate yield increased over 480 °C, the yield of lighter distillates was the highest at 480 °C and decreased at higher temperature. When the reaction pressure was increased, the heavy distillate yield decreased with increasing yields of lighter distillates and coke. Two paraffinic and two Middle East ARs were thermally cracked under the conditions of 480 °C, N₂ 0.4 MPa and 0.5 h, and the product composition and properties were compared. The yield of distillates (C₄-500 °C) was around 90 % for paraffinic ARs, and 70-80 % for Middle East ARs. The sulfur contents of the distillate products from paraffinic ARs were much lower than those of Middle East ARs, but the difference in the nitrogen contents was not significant. Pyrolyzed middle and heavy distillates were hydrotreated to investigate their hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactivities. The HDS rates of the distillates obtained from paraffinic ARs were 4-6 times higher than those of Middle East ARs. The HDN rates were comparable for the middle distillates, but the HDN rates of the heavy distillates from paraffinic ARs were lower than those from Middle East ARs.