Molecular Simulation of Chain Initiation Mechanism in Oxidation of Lubricant Base Stock

Chain initiation reactions in the oxidation process of lubricant base stock molecules were studied by molecular simulations.Two ways to initiate lubricant oxidation were investigated.They included the dissociation of chemical bonds in base stock molecules and the reaction between base stock molecules and oxygen(O_(2)),respectively.Reaction activation energy of above methods was calculated.The results show that C‒C bonds are more likely to break than C‒H bonds to generate free radicals by the pyrolysis of chemical bonds.The C‒C bonds with tertiary carbon atoms are preferential positions to crack.However,their bond dissociation energy is above 360 kJ/mol,which is difficult to occur under lubricant working conditions.The chain initiation is more likely to occur by the way that O_(2) attacks the two atoms in C‒H bonds at the same time,and is then embedded into the C‒H bond to produce hydrocarbon peroxides.And then,the O‒O bond is cracked to form hydroxyl radicals and alkoxy radicals.The C‒H bonds with tertiary carbon atoms are preferential reaction sites,the reaction activation energy of which is about 190.11 kJ/mol.

Oligomerization of 1-Decene: Catalyzation by Immobilized AlCl_3/γ-Al_2O_3 Catalyst in Fixed-bed Reactor

1-Decene was oligomerized over the supported AlCl3/γ-Al2O3 catalyst in a fixed-bed reactor. The effects of temperature and LHSV on oligomerization of 1-decene were investigated and the synthetic PAO was characterized with GC technique. Furthermore, the life of immobilized catalyst was tested and the mechanism of catalyst deactivation was discussed. The results showed that with an increasing temperature, the PAO yield increased and the kinematic viscosity of oil decreased. The GC results indicated that the synthesized PAO was a mixture consisting of dimers, trimers, tetramers and pentamers. The results of chloride content measurements and BET tests showed that catalyst deactivation could be mainly attributed to the loss of active components.

Synthesis of Polyalphaolefins on AlCl_3/TiCl_4 Catalyst

The oligomerzation reactions on different catalysts were investigated and discussed. 1-Octene, 1-decene, 1-do- decene, a mixture of olefins （with a mass ratio of w（l-octene）： w（1-decenc）：w（1-dodecene） equating to 30：40：30）, and the products from paraffin cracking were oligomerized on the AlCl3/TiC14 catalyst. The results indicated that the AlCl3 catalyst led to severe coking reaction. With an increase in carbon number of alpha-olefins, the freezing point of oligomers increased and the kinematic viscosity decreased. The oligomers formed from the mixed olefins and the paraffin cracking products showed higher kinematic viscosity. Normal paraffins contained in the cracked products could increase the freezing point of oligomers. Furthermore, the distillation range of oligomers obtained from the cracked products was close to those of oligo- mers originated from 1-octene and 1-decene, while the oligomers obtained from the mixed olefins and 1-dodecene had simi- lar distillation ranges.