自由基引发剂用于渣油减黏裂化的研究

基于热裂化按照自由基反应机理进行的特点,在高压釜式反应器中分别添加四种自由基引发剂偶氮二异丁腈(AIBN)、过氧化特二丁基(DTBP)、单质硫(S)和单质碘(I2),考察引发剂在390℃～410℃,引发剂添加量0～3000×10-6条件下对三种减压渣油减黏裂化的影响。通过测定减黏前后渣油的运动黏度和四组分的变化,对引发剂的作用机理进行了初步研究。结果表明,自由基引发剂对不同基属的减压渣油减黏裂化反应均有明显的促进作用,大小依次为:LHVR≥GDVRDQVR,并且这种促进作用在较低的反应温度下更加明显,促进效果由渣油本身的物理化学性质所决定。在同等条件下,I2和S促进渣油减黏的效果是AIBN和DTBP降黏率的两倍,这与S和I2形成氢化物的"活性原子"可以多次循环发生作用有关。与S相比,单质I2减黏促进作用更为明显。

Effect of free radical initiators addition on visbreaking of vacuum residues

The effects of four free radical initiators including azodiisobutyronitrile (AIBN), di-tert-butyl peroxide (DTBP), sulfur(S) and iodine(I₂) on the autoclave-style visbreaking of three vacuum residues were investigated under the reaction conditions of 390℃～410℃ and the initiator dosage of 0~3000×10^-6 according to free radical chain reaction mechanism of thermal-cracking of vacuum residues. The improvement mechanisms of the free radical initiators were studied by analysis of the viscosity and chemical composition of the processed oil samples. The results show that the free radical initiators improve the visbreaking of different-base vacuum residues， in which the order of improvement is LHVR≥GDVR>DQVR. The improving effect, which is dependent on the chemical-physical character of the processed residues, could be outstanding at lower reaction temperatures. The effect of I₂ or S under the same reaction condition is twice higher than that of AIBN or DTBP, which could be attributed to the circulated initiation of ‘active atom’ originated from the inorganic HI or H₂S. Compared with S, the improvement of iodine is better.