Study On Hydrocracking Of Diarylalkanes Compounds

As the most relevant petroleum model compounds, diarylalkanes(DAAs) were used to study the hydrocracking mechanism of residue, the effect of partial hydrogen pressure on cracking of 4-hexylbiphenyl, 4,4-ditertbutylbiphenyl, diphenyl-methane and 2,2-diphenylpropane were examined in a micro batch reactor under the hydrogen system, hydrogen-decahydronaphthalene system, hydrogen-decalin-tetralin system, hydrogen-decalin-tetralin-catalyst system and the hydrogen-decalin-tetralin-catalyst- CS₂ reaction system.The results show that:(1)Under the hydrogen system, the increasing of pressure promoted the hydrogenolysis reactions and inhibited the free radical reactions. The conversion of 4-hexylbiphenyl which is prone to the radical reactiongs was declined with increasing pressure. But as regard to the reactants that are not easily cracking under thermal conditions, such as 4,4-ditertbutylbiphenyl, diphenyl-methane and 2,2-diphenylpropane, the conversion will increased with the raising of hydrogen pressure.(2)Under the hydrogen-decalin systerm and hydrogen-decalin-tetralin systerm, the presence of solvent promoted the radical reactions and inhibited the hydrogenolysis reactions. Nevertheless, both kinds of reactions were prompted with the increasing of hydrogen pressure.(3)In decalin solvent and hydrogen donor tetralin existing system, the conversion of reactants raised with the increasing of pressure. Hydrogen donor tetralin restricted the taking place of free radical reaction and hydrogenolysis reaction. Hydrogenation of tetralin to decalin was promoted with the increasing of pressure, but dehydrogenation of tetralin to naphthalene was restricted. (4)In the presence of catalyst and carbon disulfide, the raising of pressure prompted the hydrogenolysis reactions and dehydrogenation. Changing of pressure had different effects on free radicals reaction.