石油沥青质的热解化学

THE CHEMISTRY OF THE THERMAL DEGRADATION OF PETROLEUM ASPHALTENES

石油沥青质热分解之所以引起人们的兴趣,是由于沥青质在石油加工过程中易生成高产率的焦炭,并使催化剂失活。总的说来是认为,生焦化学包括热不稳定键的热解生成活性物质,然后进一步反应生成焦炭。本文的数据表明:初次反应生成分子量较低的产物,这些分子中氮的存在促进了键的断裂。其它诸如环烷系的芳构化与芳环系的最终缩聚等反应将导致焦炭的生成。一个重要的新发现是焦炭的生成并不经由直接缩合反应,而是通过初次反应生成分子量较低的产物,它们的芳香度高,并含有原始沥青质中大部分的氮(氧或硫)。

The thermal decomposition of petroleum asphaltenes is of interest because of the tendency of the asphaltenes to form high yields of coke and to cause catalyst deactivation during processing. In a general sense the chemistry of asphaltene coking has been suggested to involve the thermolysis of thermallabile bonds to form reactive species which then reacts further to form coke. The current data show that the initial reactions produce lower molecular weight products in which bond cleavage is also promoted by nitrogen occurrence in the molecules. Other reactions such as aromatization of naphthenes systems and eventual condensation of the aromatic ring systems will produce coke.The most obvious new finding is that coke formation does not proceed by the immediate occurrence of condensation reactions but by the initial production of lower molecular weight species which are highly aromatic and which contain the majority of the nitrogen (as well as large portions of the oxygen and sulfur) originally present in the asphaltene.