Abstract:

Blending inferior gas oil into hydrocracking feedstock not only achieves efficient utilization of inferior gas oil, but also expands the source of feedstock for hydrocracking units, while it is really a tremendous challenge to realize ultra-deep hydrodenitrogenation (HDN) for inferior gas oil. This paper made deep analysis of the basic properties, distributions and molecular structure of nitrogen compounds in three gas oil, including straight-run VGO (SR-VGO), ebullated-bed VGO (EB-VGO) and slurry-bed VGO (SB-VGO). The results showed that nitrogen content and aromatics content of SB-VGO, especially for three-ring and four-ring PAHs, were higher than SR-VGO and EB-VGO. But the distribution and molecule structure of nitrogen compounds were similar in those three gas oil. More specifically, basic nitrogen had DBE values between 9 and 16, while DBE values of non-basic nitrogen were concentrated in 9, 10, 12 and 13. The HDN difficulty decreased in this order: SB-VGO > EB-VGO > SR-VGO. And compared to non-basic nitrogen, basic nitrogen was facile to remove during the hydrotreating process. When total nitrogen was reduced to around 100μg/g, the remaining nitrogen species were mainly neutral with DBE values of 10—14 and carbon numbers of 19—29.

Key words: inferior gas oil, distribution of nitrogen compounds, structure of nitrogen, hydrodenitrogenation, hydrocracking

摘要：

在加氢裂化原料油中掺炼劣质蜡油，既实现了劣质蜡油的高效利用，又增加了加氢裂化装置的原料来源；而实现劣质蜡油超深度加氢脱氮是劣质蜡油进入加氢裂化装置的主要技术难点之一。本文以直馏蜡油、沸腾床蜡油和浆态床蜡油为代表，分析了3种蜡油的基本性质、氮化物分布及结构，比较了3种蜡油氮化物的脱除难度，并探究了氮化物在加氢过程中的转化规律。结果表明：与直馏蜡油和沸腾床蜡油相比，浆态床蜡油的氮含量和稠环芳烃含量更高；但3种蜡油氮化物的分布与分子结构相近，其中碱性氮化物不饱和度（DBE）主要分布在9~16，中性氮化物DBE则集中分布在9、10、12和13。氮化物的脱除难度顺序为：浆态床蜡油>沸腾床蜡油>直馏蜡油。在加氢转化过程中，碱性氮化物优先脱除，当蜡油总氮量脱除至100μg/g时，产物的剩余氮化物主要以DBE分布在10~14、碳数分布在19~29的中性氮化物为主。

关键词: 劣质蜡油, 氮化物分布, 氮化物结构, 加氢脱氮, 加氢裂化