加氢精制深度对催化裂化柴油性质的影响

INFLUENCE OF HYDROTREATING DEPTH ON PROPERTIES OF LCO

在固定床小型加氢实验装置上,以不同的催化裂化柴油为原料,模拟两段加氢处理技术生产低硫低芳烃柴油,考察加氢精制深度对柴油性质的影响。评价时第一反应器装填Ni-W催化剂,第二反应器装填Pt-Pd贵金属催化剂,通过调整空速和反应压力,得到不同加氢精制深度的柴油。结果表明:经过深度加氢精制,柴油的密度、折射率、硫含量、氮含量、总芳烃含量均减小,氢含量、十六烷值提高;加氢精制后的柴油芳烃含量与化学氢耗、折射率、密度、十六烷值成线性关系;不同催化裂化柴油加氢精制后的芳烃含量与十六烷值的线性拟合斜率和截距各不相同,与柴油的烃类组成和碳数分布密切相关,截距代表了芳烃完全饱和时的十六烷值,斜率反映了芳烃饱和对十六烷值的贡献;对总芳烃质量分数为88.2%的催化裂化柴油LCO-Ⅰ,芳烃质量分数每降低1%,十六烷值可提高0.26个单位,芳烃完全饱和时十六烷值可达到42,对总芳烃质量分数为31.3%的混合柴油LCO-Ⅱ,芳烃质量分数每降低1百分点,十六烷值可提高0.66个单位。

The influence of hydrotreating depth on the properties of diesel with low-sulfur and low- aromatic was investigated by simulating two-stage hydrotreating technology using two separate fixed- bed microreactors and different light cycle oils （LCO） feeds. The first reactor was packed with Ni-W sulfide catalyst, and the second reactor was packed with Pt-Pd noble metal catalyst. By adjusting the space velocity and reaction pressure, diesels with various hydrotreating depths were obtained. The re- sults show that after deep hydrotreating, the density, refractive index, and the content of sulfur, nitro- gen, and total aromatics decrease, while the hydrogen content and cetane number （CN） increase. The aromatic content of hydrotreated diesel is linearly related to the chemical hydrogen consumption, refractive index, density, and CN. The slope and intercept of the linear fitting of aromatic content and CN are different for various LCO, closely relating to the hydrocarbon compositions and the carbon number dis- tributions. The intercept represents the CN of diesel after full aromatic saturation, and the slope reflects the contributions of aromatic saturation to CN. For feed LCO-Ⅰ with 88.2% of aromatic content, the CN will increase 0.26 units for every 1 percentage point reduction in aromatic content, and will reach up to 42 units after aromatic saturation in full. For the hybrid diesel LCO-Ⅱ with 31.3% of aromatic con- tent, every 1 percentage point reduction of aromatic content will increase the CN of 0. 66 units.