Study On The Green Synthesis Technology Of Succinimide Ashless Dispersant

Ashless dispersant is one of the important additives of lubricating oil, and is to disperse the precursors of oil sludge, paint film and carboning in oil, which can prevent their formations and prolong the operating life of engine and the oil change period. In this paper a green process was applied to synthesize ashless dispersant of polyisobutylene succinimide (TEPA) without pollution source of liquid chlorine.Synthesis process of ashless dispersant TEPA including alkylation and animation were studied in this paper. (1)Alkylation: Reactants of polyisobutylene (PIB) and maleic anhydride (MA) were firstly mixed uniformly and then were initiated to form polyisobutylene succinic anhydride (PIBSA) by dropping into benzoyl peroxide (BPO) in batches as initiator under the protection of N₂ and a reaction temperature (100 to 180℃). The effects of reaction atmosphere, reaction temperature and time, stirred speed, the contents and its adding ways of initiator and maleic anhydride were studied. Optimum reaction conditions were obtained as follows: under the protection of N₂, temperature of 150℃, reaction time of 12h, BPO/PIB mass ratio of 0.035, MA/PIB mole ratio of 1.3, stirred rate of 250rpm and dropping addition of BPO solution in butanone at 30min interval. Under these conditions, the highest conversion of PIB could be achieved. (2)Amination: Diethylenetriamine(DETA) was dropped into the the alkylation product (PIBSA) in batches under the protection of N₂ and temperature of 40℃ to 80℃. Amination reaction was carried out at temperature of 90℃ to 150℃ for 2h to 10h and then ashless dispersant of polyisobutylene succinimide (TEPA) would be obtained after dehydration with the operations of vacuum distillation and filtration. The effects of reaction temperature and time, stirred speed, the contents and its adding ways of diethylenetriamine were studied. Optimum amination conditions were determined as follows: PIBSA/DETA mole ratio of 1.1, reaction temperature of 140℃, amination time of 6h, amination stirred rate of 200rpm, and dropping addition of DETA at 50℃. Under these conditions, the highest yield of TEPA could be achieved.Infra-red (IR) spectrometry was used to analyze the products of alkylation andanimation. IR analysis indicated that both of the results were accorded with their standards IR spectrum and that the products of alkylation and animation were polyisobutylene succinic anhydride and ashless dispersant TEPA. Low temperature dispersivity of ashless dispersant TEPA was analyzed by the sludge spot distribution test (SDT). The results showed that the ashless dispersant prepared had low temperature dispersivity. The SDT value of TEPA increased first and then declined with the rising of animation temperature, and the optimum reaction temperature was 140℃. SDT was constant and then decreased when DETA/PIBSA mole ratio was more than 1.3, and the optimum mole ratio of DETA/PIBSA was 1.1.