关键词: 油页岩, 页岩灰, 热解, 金属氧化物, 催化

Abstract:

In the solid-solid mixing pyrolytic process,the ash or bed material may influence the pyrolytic behaviors of the oil shale.Thus,pyrolysis of oil shale mixed with four metal oxides Al₂O₃,MgO,CaO and Fe₂O₃ were investigated.The results showed that CaO had a strong influence to the yields of products,and particularly promotes the formations of shale oil and char,while decreases the yield of gas product.On the contrary,Al₂O₃ in acidic property can most distinctly promote the devolatilization of oil shale with an augmented yields of shale oil,water and gas products.Comparatively,the effects of MgO and Fe₂O₃ to product yields were much weaker.All of the four metal oxides can promote the formation of H₂,CH₄ and C₂ hydrocarbons.The content of CO₂ decreased extremely for CaO,while all other metal oxides played promoting role to the formation of CO₂.H₂ and CH₄ can be most distinctly increased for Fe₂O₃ and Al₂O₃,respectively.The content of aromatics in shale oil can be augmented by all of the four metal oxides and the effect of Fe₂O₃ was most significant.For the components of chain hydrocarbons,the short-chain (C₆-C₁₂) alkanes and alkenes were promoted for both of CaO and MgO,while only the short-chain alkanes were increased under the effect of Al₂O₃.It was deduced that the alkalinic CaO and MgO firstly reacted with the fatty acids of the organic matters,forming a fatty acid salt.Then,a decarboxylating step was followed in the way of releasing CaCO₃,simultaneously generating intermediates that could be converted to both of alkanes and alkenes.However,under the acidic Al₂O₃,the decarboxylation product was CO₂,determined a prevalent alkane product.

Key words: oil shale, shale ash, pyrolysis, metal oxide, catalysis