【作者】 杨在峰；

【导师】 郭新闻； 王祥生；

【作者基本信息】 大连理工大学 ， 工业催化， 2011， 硕士

【摘要】 随着汽车工业的发展和人们环保意识的增强,汽油的标准也愈来愈严格。我国最新汽油标准中规定,硫含量不得高于50 ppm,烯烃不高于25%(体积百分数,以下同),芳烃与烯烃含量之和不高于60%。我国汽油组成中约80%为FCC汽油,其表现为硫和烯烃含量高的特征,但芳烃还有上升空间。在使用加氢脱硫技术降低硫含量的同时,会导致烯烃含量的降低,从而辛烷值也会随之降低。为了保住产品的辛烷值,可以通过芳构化的方法将FCC汽油中的烯烃和烷烃转化高辛烷值的芳烃,从而使汽油的辛烷值不降低,亦可将直镏汽油等低品质汽油改质,达到提高汽油品质的目的。纳米HZSM-5分子筛具有外表面酸中心多,吸附量大,吸附能力强,扩散阻力少等性能特点,使具有优良的芳构化性能和抗积碳能力,已应用于多种烃类转化反应中。水热处理是调节催化剂酸性和稳定性的常用方法,一定浓度的硝酸酸洗可以除去水热处理后催化剂孔道中堆积的非骨架铝,起到疏通孔道的作用,金属镓和锌具有良好的芳构化能力。以不同温度水热处理并酸洗后的与氧化铝混合挤条后的纳米HZSM-5为母体,分别以金属Ga和Zn为活性组分制备催化剂,并尝试用其他金属对其改性,考察其对FCC和直镏汽油的芳构化能力。通过上述研究,得出以下结论：(1)以600℃水热处理并酸洗的HZSM-5为母体制备的Ga/HZSM-5在Ga系催化剂中表现出了最优的芳构化性能,在反应温度为480℃、WHSV=1 h-1的条件下,其所得产品中芳烃含量为58.3%,C3+4含量为7.6%。(2)水热处理可以降低纳米HZSM-5的酸量,同时降低其L酸及B酸量,随着水热处理温度的升高,酸洗后的水热处理HZSM-5的L/B值升高,酸强度降低。(3)使用金属Fe、Cu和Cr的盐对Ga/HZSM-5进行二次改性,在选定条件下,对其芳构化性能的提高并无有利影响。(4)La和P改性后的Zn/HZSM-5芳构化效果要好于Cu和Ni改性,并且以2%Zn及1%La的负载量为最佳。在反应温度为380℃、WHSV=1.5h-1时,其产品中芳烃含量为22.1%,烯烃25.7%,计算辛烷值89.7。(5)Ga和Zn改性后的HZSM-5遵循相同的反应机理,并不因活性组分不同而导致芳构化机理改变。更多还原

【Abstract】 Gasoline standards have become more and more stringent since the development of auto industry and human notice on environment protection. In China, the latest standard in which less than 50 ppm sulfur content, no more than 25V% olefins content and no more than 60V% aromatics plus olefins content is required has been executed in some city.In China, about 80% gasoline comes from FCC gasoline which has high sulfur and olefins content while aromatics still has growth room. The conventional hydrotreating technology results in the significant reduction of RON dut to the saturation of olefins in FCC gasoline. Aromatization can transfer olefins to aromatics to keep the octane number. The quality of straight run gasoline can also be improved by aromatization.ZSM-5 has been used in many hydrocarbon conversion reactions due to its excellent aromatization, isomerization and alkylation ability. The parent nano-HZSM-5 exhibited the properties of smaller crystallite, shorter micropore, and more acidic centers at external surface. Hydrothermal treatment can modify the acidity of HZSM-5 and its stability on the basis of retaining crystal structure. HNO3 treatment can remove the non-framework Al in the zeolite channel. Ga and Zn are excellent active component on aromatization process. In the study nano-HZSM-5 were prepared by hydrothermal & HNO3 treatment and loading Ga, Zn and other metal oxides. The aromatization performances of prepared catalysts for FCC and straight run gasoline were evaluated.Based on the above investigations, we got the following conclusions.(1) The Ga/HZSM-5 after nanoscale HZSM-5 was hydrothermal treated at 600℃showed the best aromatization performance (aromatization and C3+C4 contents were 58.3V%and 7.6V%, respectively) at reaction temperature 480℃, WHSV=1 h-1.(2) The total acid amount (including Leswis and Br(?)nsted acid) and strength decreased, and the ratio of L/B of prepared HZSM-5 increased as the hydrothermal treatment temperature rising.(3) Catalyst Ga/HZSM-5 which modified by Fe, Cu and Cr didn’t show any advanced aromatization performance on FCC gasoline in the selected reaction conditions.(4) Catalyst Zn/HZSM-5 modified by La and P showed better aromatization performance than catalyst modified by Cu and Ni respectively. The evalution of the prepared catalyst which was loaded with 2% wt.Zn and 1wt.% La for FCC gasoline aromatization was conducted at 380℃, WHSV=1.5 h-1. After aromatization, the aromatic content in gasoline increased from 15.2V% to 22.1V%, and olefin content decreased from 40.1V% to 25.7V%. Meanwhile, gasoline RON was 89.7.(5) HZSM-5 modified by Ga and Zn followed the same mechanism in the aromatization process no matter what the active component was.更多还原