FCC催化剂组元上轻柴油裂化反应焦炭的结构组成

STRUCTURE AND COMPOSITION OF COKE DEPOSITED ON COMPONENTS OF FCC CATALYST DURING GAS OIL CRACKING

结合柱色谱层析分离、GC/MS和场解析质谱(FDMS)技术,建立了一种可萃取焦的分离检测方法,并考察了不同FCC催化剂组元轻柴油裂化反应焦炭的组成结构。结果表明,在较低反应温度下(400～460℃),Y型沸石上的焦炭含较大比例的可萃取焦,USY沸石的可萃取焦所占比例低于REY沸石的,表明USY沸石上焦炭的分子缩合度高于REY沸石;较高反应温度下(520℃),沸石上的焦炭中95%以上以高缩合度不可萃取焦状态存在。基质上的焦炭中,仅在较低的反应温度下(400℃)含有很少量可萃取焦,焦炭缩合度远高于沸石组分上的焦炭。可萃取焦以多环芳烃(3～8环结构,烷基侧链碳数不大于8)为主要组分;不可萃取焦呈无定形状态,nH/nC比在0.3～0.5之间。

An analytical method combining silica gel column chromatography separation, GC/ MS and FDMS was developed to determine the composition and structure of the soluble coke (S-coke). The characteristics of coke deposited on Y zeolites and the matrix of FCC catalyst during gas oil cracking under different reaction temperatures were investigated. The results indicate that, under lower reaction temperatures (400-460°C), most of the coke deposited on Y zeolites are soluble. Though the coke content was lower on USY zeolites, the coke substance was more condensed than those on REY zeolites. Under a higher temperature 520°C, insoluble coke (Ins-coke) appeared to be the main component of the coke. Only a little part of coke on the matrix was soluble even under a lower reaction temperature 400°C, which indicates that coke substance deposited on the matrix is more condensed than on Y zeolites. The S-coke comprised mainly methyl polyaromatic derivatives with 3-8 aromatic rings, having methyl amounts &le8. The Ins-coke was amorphous, with aromatic H/C ratio: 0.3-0.5.