The devolatilization of oil shale during retort process would cause significant changes to the pore structure of oil shale semi coke

which would have important effects on the semi coke combustion and ash formation.The pore structures of oil shale semi coke prepared at different retorting temperatures and different residue times were analyzed by SEM and nitrogen adsorption and desorption.The results were discussed with the combustion results of the same samples which conducted by other researchers.The results show that

the pore specific area and volume of oil shale semi coke would initially increase and then decrease with the increase of retorting temperature within experimental parameters range

which might be explained by coke blocking pore.With the increase of residue time

pore coalescence would happen.So the pore specific area of oil shale semi coke would initially increase and then decrease

while the pore specific volume would increase.