不同类型氧化铝对FCC轻汽油芳构化性能影响

Effect of alumina on aromatization performance of FCC light gasoline

针对第六阶段汽油国家(国Ⅵ)标准大幅度降烯烃同时保辛烷值的生产需要,本文通过改变氧化铝基质类型,制备了系列催化裂化(FCC)轻汽油芳构化催化剂,并对催化剂酸性质和织构性质进行调变。采用X射线衍射(XRD)、N;吸附脱附、扫描电子显微镜(SEM)、红外光谱(IR)和吡啶红外光谱(Py-IR)等手段对催化剂的物理性质进行表征,并以工业FCC轻汽油为原料对催化剂芳构化性能进行评价。实验结果表明,不同类型氧化铝的引入未对ZSM-5分子筛晶型产生影响,但可以显著调变ZSM-5分子筛的表面酸性,增加L酸中心数量。具有均一和相对较小比表面积和孔容的氧化铝材料更有利于轻汽油芳构化性能,轻汽油产品中,烯烃大幅下降(体积分数减少18.18%),异构烷烃(体积分数提高10.51%)和芳烃(体积分数提高2.75%)增幅较为明显,辛烷值损失(-5.1)较小并且可控。

In order to meet the olefins requirement of the nationalⅥstandard,a series of FCC light gasoline aromatization catalysts were prepared by changing the alumina species.Besides,the acidity and texture properties of the catalysts were investigated.The physico-chemical properties of the catalysts were characterized by XRD,N;adsorption desorption,SEM,IR and Py-IR.The aromatization properties of the catalysts were evaluated using FCC light gasoline as feedstocks.The results showed that the introduction of different types of alumina had no effect on the structure of ZSM-5 molecular sieve.However,the acidity of ZSM-5 zeolite could be significantly changed and the Lewis acid sites increased significantly.Besides,alumina materials with uniform and relatively small surface and pore volume were more favorable to the aromatization reaction of light gasoline.The olefins volume fraction of light gasoline decreased 18.18%significantly,volume fraction of isoparaffins increased 10.51%and aromatics increased 2.75%,and octane loss was small(-5.1)and controllable.