供氢(氘)剂在减压渣油四组分裂化中的作用及其同位素效应

研究了辽河减渣四组分在微型高压釜内中临氮热裂化、临氢热裂化和临氢催化加氢反应，考察了供氢剂或供氘剂对上述反应的影响。结果表明，临氮热裂化时沥青质是大量生焦的物种，胶质的生焦能力不显著，芳香分、饱和分不生焦；临氢热裂化沥青质生焦量减少，胶质很少生焦，芳香分和饱和分不生焦；临氢催化加氢时，辽河减渣四组分在临氢反应基础之上，生焦量进一步降低。辽河减渣四组分在临氮热裂化、临氢热裂化和临氢催化加氢过程中添加供氢剂或供氘剂后，生焦反应得到显著抑制，相比之下供氢剂的作用更为明显。三种氢源都具有抑制渣油四组分缩合或缩聚反应的作用。渣油四组分从供氢剂或供氘剂中获得氢（氘）的能力不同，沥青质>胶质>芳香分≈饱和分。就同一组分而言，供氢剂或供氘剂的表观供氢（氘）率随反应条件不同而不同，临氮热裂化> 临氢热裂化>临氢催化加氢过程。供氢剂与供氘剂在所有的过程中都存在明显的动力学效应，并且这个动力学效应随加工环境的不同而变化，在临氮热裂化过程中动力学同位素效应明显。在临氢热裂化过程，尤其是催化加氢裂化过程中动力学效应逐渐变得不明显。2H-NMR分析表明，氘代四氢萘的环烷环中的α位比β位的脱氢选择性高，氘代四氢萘脱氢选择性大小的顺序为：临氮热裂化>临氢热裂化>临氢催化加氢过程。

Hydrogen (deuterium) donor effects and isotopic effect in substractions cracking in residue

Four subfractions (saturates, aromatics, resin and asphaltene, SARA) from Liaohe vacuum residue (LHVR) were cracked in the thermal, hydrothermal and catalytic hydrocracking system without or with detuerated tetralin and tetralin in a high-pressure microreactor. The effects of D-donor, H-donor and molecular hydrogen on the cracking reaction of SARA were investigated. The results show that asphaltene is the major precursor of coke, and resin could produce some coke in thermal cracking. However, aromatics can hardly result in coking, and saturates is not precursor of coke compared with asphaltene and resin. In the hydrothermal cracking and catalytic hydrocracking systems, the trend of coking of SARA could be decreased by participation of molecular hydrogen, especially in the catalytic hydrocracking system. Three hydrogen sources including D-donor, H-donor and H_2 could decrease the formation of coke and asphaltene of SARA, especially the first two donors. D-donor and H-donor have the similar effect on the cracking and condensation of SARA. However, there is clear isotopic effect between H-donor and D-donor based on the difference of donation ability at same condition. The stable isotope study shows that C-H bond scission of tetralin or C-D bond scission of detuerated tetralin is incorporated into the race-controlling reaction pathway in the cracking systems of SARA. The degree of isotopic effect shows the race-controlling reaction pathway depended on the reaction system. The isotopic effect in thermal cracking system was clearest among the hydrothermal cracking and catalytic hydrocracking systems as a result of the change of race-controlling reaction pathway of thermal cracking of SARA by molecular hydrogen and dispersed catalysts.