饱和烃促进渣油热反应初期生焦的考察

PROMOTING EFFECT OF SATURATE HYDROCARBONS IN INITIAL COKE FORMATION FROM PETROLEUM RESIDUA UNDER THERMAL CRACKING

研究了石油渣油饱和烃的热裂化夺氢化学对渣油热反应体系生焦的影响。对由饱和烃 供氢探针、饱和烃 沥青质组成的二元模型反应体系 ,以及由饱和烃 供氢探针 沥青质组成的三元模型反应体系 ,分别进行高压热反应 ;然后关联二元反应体系和三元反应体系中饱和烃夺氢能力及供氢探针的供氢量和沥青质生焦率。结果表明饱和烃夺氢能力可促进沥青质生焦 ;并且饱和烃的热裂化夺氢反应性能与饱和烃的物理沉积性能相比较 ,前者更能促进沥青质形成凝聚相而生焦。进而测定四种减压渣油的热反应生焦趋势 ,发现渣油饱和分的夺氢量与渣油热反应初期的生焦趋势密切相关 ,而较苛刻的条件下的生焦趋势主要是由原料渣油残炭值所决定。

Relationship between hydrogen abstraction abilities (H a) of saturates in vacuum residua and initial coke formation under thermal treatment was tentatively correlated in this study H a of saturate structures found in residue species crack down by radical mechanism and favor to deplete transferable hydrogens in hydroaromatic structures, causing radicals of coke precursor uncapped and concentrated, and accelerating coke formation Model reaction systems composed of saturated hydrocarbons (i e n hydrocarbons, paraffins, or residue saturates series) and asphaltenes showed that H as of saturated hydrocarbons increased coke formation from asphaltenes When hydrogen abstraction behaviors of saturate hydrocarbons under thermal cracking and precipitating properties of saturate hydrocarbons were evaluated, the former showed the stronger effect on controlling coke formation through liquid asphaltene phase Then hydrogen amounts abstracted by four residue saturates (H A) were correlated with coke induction period of corresponding residue under thermal cracking Results indicated that higher hydrogen amount abstracted by saturates shortened coke induction period Further investigation gave evidence that bulk coke formation during higher severities seems to be irrelevant to hydrogen abstraction behaviors of saturates, but a positive function of carbon residue of the residua was found