Wei Qiang, Zhang Jiarui, Liu Xiaodong, Zhang Pengfei, Wang Shuqin, Wang Yan, Zhang Zhenli, Zhang Tao, Zhou Yasong
State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, China.
Petrochemical Research Institute, China National Petroleum Corporation, Beijing, China.
Front Chem. 2019 Oct 29;7:705. doi: 10.3389/fchem.2019.00705. eCollection 2019.
Citric acid-treated zeolite Y (CY) and zeolite beta were mechanically mixed to obtain composite zeolites (CY-Beta) with various zeolite beta contents. The composite zeolites were used as the acid components of hydrocracking catalyst supports. The physical and chemical properties of the supports and catalysts were analyzed by N adsorption-desorption, XRD, SEM, and NH-TPD. The mechanical mixing of CY and zeolite beta does not destroy the textual properties of the original zeolites. However, the acidity of the composite zeolite does not fit the linearly calculated value of the two zeolites because some of the acid sites are covered or reacted with other acid sites during the mixing process. In addition, weak acid sites favor the high yield of tail oil with low BMCI value. Compared with the CY-based and beta-based catalysts, the conversion and light oil yield of the CY-Beta-based catalyst was increased. The conversion, light oil yield, and petrochemical yield of the Ni-W/20CY-Beta(20)/ASA catalyst are 78.15, 65.0, and 83.7%, respectively. The BMCI value of the tail oil is 4.7, and the aromatic potential content (APC) of heavy naphtha (boiling point 65-177°C) is 42%. The 1,500 h pilot plant test of Ni-W/20CY-Beta(20)/ASA at 350°C, 7.0 MPa, 2.0 h LHSV, and 800 H/oil (v/v) shows that the activity remains stable during the 1,500 h evaluation. The heavy naphtha (APC about 41.0) yield of 41.2 illustrates that the catalyst has the ability to aromatize and cyclize the light fractions. The yield of diesel is about 25% with a cetane index (CI) of 59.2; the frozen point is lower than -45°C, and the cold filter plugging point is -35°C, demonstrating the isomerization performance for middle distillations. The yield of tail oil is 14.9% with a BMCI of 4.4, showing the high hydrogenation performance of the catalyst to transform the un-cracked tail oil to saturated hydrocarbon in order to reduce the BMCI value.
用柠檬酸处理的Y型沸石（CY）与β型沸石进行机械混合，以获得具有不同β型沸石含量的复合沸石（CY - Beta）。这些复合沸石用作加氢裂化催化剂载体的酸性组分。通过N吸附 - 脱附、XRD、SEM和NH - TPD对载体和催化剂的物理化学性质进行了分析。CY与β型沸石的机械混合并未破坏原始沸石的结构性质。然而，复合沸石的酸度并不符合两种沸石线性计算的值，因为在混合过程中一些酸位点被覆盖或与其他酸位点发生了反应。此外，弱酸位点有利于获得低BMCI值的尾油高产率。与基于CY的催化剂和基于β型沸石的催化剂相比，基于CY - Beta的催化剂的转化率和轻油产率有所提高。Ni - W/20CY - Beta(20)/ASA催化剂的转化率、轻油产率和石化产率分别为78.15%、65.0%和83.7%。尾油的BMCI值为4.7，重石脑油（沸点65 - 177°C）的芳烃潜含量（APC）为42%。在350°C、7.0 MPa、2.0 h LHSV和800 H/oil（v/v）条件下对Ni - W/20CY - Beta(20)/ASA进行1500小时的中试装置测试表明，在1500小时的评估过程中活性保持稳定。41.2%的重石脑油（APC约为41.0）产率表明该催化剂具有使轻质馏分芳构化和环化的能力。柴油产率约为25%，十六烷指数（CI）为59.2；凝点低于 - 45°C，冷滤点为 - 35°C，表明该催化剂对中间馏分具有异构化性能。尾油产率为14.9%，BMCI为4.4，表明该催化剂具有高加氢性能，可将未裂化的尾油转化为饱和烃以降低BMCI值。
