接触剂性质和油膜厚度对减压渣油接触裂化反应性能的影响

Effects of Contact Agent Properties and Oil Film Thickness on Contact Cracking of Vacuum Residues

为考察接触剂对减压渣油接触裂化反应的影响,以石家庄减压渣油为原料,采用热解色谱(Py-GC)和热重质谱(TG-MS)分别评价无孔无酸接触剂(A)、有孔无酸接触剂(B)和有孔有酸接触剂(C)的孔结构、酸性,以及接触剂上油膜厚度对减压渣油裂化反应条件和反应产物的影响。结果表明,与无孔接触剂相比,接触剂上孔道的引入,使减压渣油分子能进入到孔径大于10 nm的孔道进行初步裂化,初步裂化产物能够进入孔径小于10 nm的孔道内进行二次裂化,生成更小分子。在A剂上减压渣油的油膜厚度对其热裂化反应产物的分布和生焦率没有明显影响;在B剂上减压渣油热裂化反应强度增强,生焦率增大至12%~13%;在C剂上,随着减压渣油油膜厚度的减小,其裂化产物中C 12-和C 12~C 20馏分相对质量分数增大,C 20+馏分相对质量分数减小,生焦率增大。TG-MS结果表明,接触剂上酸中心的引入大大降低了减压渣油的起始裂化温度。

Effects of non-porous acid-free agent(A),porous acid-free agent(B),porous acid agent(C)and film thickness on contact cracking of Shijiazhuang vacuum residues were investigated with pyrolysis chromatograph(Py-GC)and thermogravimetric mass spectrometer(TG-MS).Experimental results indicate that film thickness of vacuum residues formed on the non-porous contact agent is in the scale of micrometers,but the film thickness of the porous contact agent is in the scale of nanometers.Compared with non-porous contact agent,for porous contact agent,it can enable vacuum residue molecules to enter its pores which diameter is larger than 10 nm and initially crack there.The above initial cracking products then can enter the pores which diameter is less than 10 nm for secondary cracking reactions and generate smaller molecules.Oil film thickness of vacuum residues on the A agent has no significant effect on thermal cracking products distribution and coke yield.For the B agent,it can increase thermal cracking reaction intensity of vacuum residues,and also increase coke yield up to 12%-13%.For the C agent,due to thinner oil film,it can increase C 20-and C 12-C 20 mass fraction,but decrease C 20+mass fraction,and also increase coke yield.TG-MS results show that the acidity in the contact agent can significantly reduce initial cracking temperature of vacuum residues.