Reaction And Evolution Characteristics Of Intermediate During The Pyrolysis Of Oil Shale

The reaction and evolution characteristics of intermediates(pyrolysis bitumen)for pyrolysis of oil shale are investigated to make a better understanding of reaction mechanism of oil shale pyrolysis.Pyrolysis experiments were performed in traditional Fischer Assay reactor at different temperatures and the pyrolysis intermediates were obtained from shale char by Soxhlet extraction apparatus.The yield,composition and molecular structure of shale oil and pyrolysis intermediates are comprehensively analyzed.The generation and consumption of intermediates during pyrolysis process take place simultaneously,which can exist stably at the temperature range of 350-400? and reach the highest yield at 375?.Pyrolysis intermediates are unstable at high temperatures,which can be transformed to final pyro]ysis products quickly.With the consumption of intermediates,the components rich in hydrogen tend to transform into shale oil,while the intermediates poor in hydrogen tend to transform into semicoke.According to NMR spectrum of intermediates product at 375?,gas-potential and oil-potential carbons show contents of 11.77%and 85.79%,respectively.Intermediates derived at different pyrolysis temperatures have similar compound composition,and the content of light components will increase as the pyrolysis temperature rises.Results from cracking of pyrolysis intermediates show that heteroatom-containing compounds can be first released from kerogen to form components of intermediates products.Aromatic hydrocarbons in decomposition of intermediates are mainly mononuclear structures with long alkyl side chains.The aliphatic hydrocarbons in pyrolysis intermediates have longer average chain length than shale oil has,which can be shorter during further pyrolysis and converted into shale oil.Alkenes in shale oil may be mainly derived from direct decomposition of kerogen,without experiencing the stage of intermediates.