流化催化裂化汽油改质前后组分变化分析

An Analysis of Changes in FCC Gasoline Components before and after Upgrading

生产低硫、低烯烃和高辛烷值的清洁汽油,是国家保持能源经济可持续发展的必然要求。由于我国原油组成中重质油比重较大,造成我国80%以上的商品汽油来源于流化催化裂化(FCC)汽油。缘于原油性质和FCC的工艺特点,决定了其产品中硫含量和烯烃含量高,商品汽油中90%以上的硫和绝大部分烯烃均来自于FCC汽油。所以,降低FCC汽油硫含量和烯烃含量是生产清洁汽油的关键。本文分析全馏分流化催化裂化汽油加氢改质前后烃类组成、碳数分布、辛烷值贡献的变化。改质前,正构烷烃含量占汽油馏分的5%～10%(体积分数)左右,异构烷烃含量占汽油馏分的30%(体积分数)左右,烯烃含量占汽油总量的30%(体积分数)以上,环烷烃主要集中在C6～C8之间,芳烃主要分布在C7～C10之间,碳数主要分布在C5～C8之间。改质后,正构烷烃、烯烃含量下降,异构烷烃和芳烃含量上升,总体辛烷值下降,高辛烷值的C5、C6烯烃损失严重。在反应体系中,增加烯烃的骨架异构化,并使其发生氢转移反应,可生成高辛烷值的异构烷烃,避免低辛烷值的正构烷烃生成,同时促进烯烃自身氢转移和烯烃与环烷烃之间氢转移反应,增产芳烃,可以提高改质后FCC汽油的辛烷值,为流化催化裂化汽油加氢改质路线的选择和工艺优化提供理论指导。

The production of low-sulfur,low-olefin and high-RON clean gasoline products is essential for China to maitain the sustainability of its energy supply and economy.As heavy crude oil represents a large proportion of China＇s crude oil supply,over 80% of gasoline products sold in China are derived from FCC gasoline.By the nature of crude oil and the characteristics of FCC technology,FCC gasoline has high contents of sulfur and olefin.Over 90% of sulfur and the majority of olefin in commercial gasoline products are from FCC gasoline.For these reasons,reducing the contents of sulfur and olefin in FCC gasoine is the key to producing clean-burning gasoline.This article analyzes the changes in hydrocarbon composition,carbon number distribution and RON contribution of full-range FCC gasoline before and after hydropgrading.Before the upgrading, normal paraffin represented 5%-10% （by volume fraction） of gasoline fraction,isoparaffin represented about 30% and olefin represented over 30%.Most cycloparaffins were between C6-C8,arenes distributed between C7-C1o and carbon numbers were primarily distributed between Cs-Cs.After the contents of normal paraffins and olefin dropped,the contents of isoparaffins and arenes were primarily the upgrading, rose, total RON fell and C5 and C6 olefins with high RON dropped considerably.In the reaction system,strengthening olefin skeletal isomerization and inducing a hydrogen transfer reaction can generate isoparaffins with high octaine numbers and avoid the production of normal paraffins with low RON,while simultaneously promoting olefin＇s hydrogen transfer and the hydrogen transfer reaction between olefin and cycloparaffins.Increasing the contents of arenes can raise the RON of FCC gasoline after upgrading ,in turn providing theoretical guidance for the selection and optimization of FCC gasoline hydro-upgrading routes