【作者】 宋毅；

【导师】 翟玉春；

【作者基本信息】 东北大学 ， 冶金物理化学， 2014， 博士

【摘要】 在石油化工领域中,柴油馏分非临氢降凝加工过程是柴油改质、产品升级的核心技术之一。柴油馏分油非临氢降凝的化学本质是在沸石催化下直链烃异构化和裂解反应。适当调整沸石基催化剂的异构化与裂解活性,可以降低气态烃的产率,从而提高汽、柴油的总产率,尤其是柴油产率。针对这一科学命题,本论文对系列沸石催化剂及相关催化过程进行基础和应用研究。以环己胺(CHA)或六亚甲基亚胺(HMI)为结构导向剂,在Na2O-SiO2-Al2O3-H2O-CHA(HMI)水热体系中合成出ZSM-35和MCM-22亚微米沸石及MCM-22/ZSM-35共结晶沸石。考察了凝胶组成、晶化温度和时间、合成釜转速及十二烷基苯磺酸钠表面活性剂的存在对合成沸石的晶相、形貌和粒径的影响。合成的ZSM-35和MCM-22结晶性好、相纯度高,其中位径(D50)分别可减小至590 nm和770 nm,而MCM-22/ZSM-35共结晶沸石的中位径在1500～2500 nm之间。以ZSM-5、MCM-22、MCM-22/ZSM-35、ZSM-35、MOR、β. Y等沸石为催化剂主体,在不同反应温度和压力下,考察了该系列沸石的孔结构对模型化合物1-己烯异构化和裂解活性的影响。结果表明,对于十二元环孔口的沸石,具有一维孔道结构的丝光沸石(MOR)对己烯裂解反应的催化活性较高,己烯骨架异构化催化活性较低；三维孔道结构的p和Y沸石对己烯裂解、烯烃聚合反应活性均较高,但对己烯骨架异构化催化活性均较低。对于十元环孔口的沸石,具有二维孔道结构的ZSM-35和MCM-22亚微米沸石及MCM-22/ZSM-35共结晶沸石具有较高的己烯骨架异构化性能；三维孔道结构的ZSM-5沸石的异构化和裂解初活性均较高。在反应温度270℃、压力0.2 MPa、1-己烯重时空速1.0 h-1和H2/1-C6H12=8(摩尔比)条件下,1-己烯骨架异构体产率按ZSM-5、 MCM-22、MCM-22/ZSM-35、ZSM-35的顺序递增,但沸石ZSM-5仍是催化己烯骨架异构化的主要活性组分,而ZSM-35适合作为改进己烯骨架异构化性能的助剂。以沸石ZSM-5为主要活性组分,制备ZSM-5(99.0%)/ZSM-35(1.0%)复合沸石催化剂,分别以催化裂化柴油、减一线馏分油、常三线馏分油及加氢裂化尾油为原料油,在小型(500 mL)反应装置上,评价该复合沸石催化剂的非临氢降凝性能,并对操作条件进行优化和验证。结果表明,在适宜反应条件下,与ZSM-5工业催化剂相比,用ZSM-35改进的复合沸石催化剂对上述不同原料油均具有较好的非临氢降凝性能。对催化裂化柴油非临氢降凝过程,适宜反应温度327℃、压力0.2 MPa、重时空速1.5 h-1,柴油产率为94.02%,凝点为-21℃,凝点降低26℃；对常三线馏分油非临氢降凝过程,适宜反应温度310℃、压力0.2 MPa、重时空速1.0h-1,柴油产率为94.61%,凝点为-21℃,凝点降低43℃；对减一线馏分油非临氢降凝过程,适宜反应温度353℃、压力0.2 MPa、重时空速1.5h-1,柴油产率为93.92%,凝点为-21℃,凝点降低30℃；对加氢裂化尾油非临氢降凝与润滑油基础油生产过程,适宜反应温度400℃、压力0.2 MPa、重时空速1.2 h-1,基础油产率可达92.53%,基础油凝点不高于-20℃,其凝点下降幅度高达52℃。在适宜操作条件下,对ZSM-5(99.0%)/ZSM-35(1.0%)催化剂进行柴油馏分油非临氢降凝中试评价。结果表明,该复合沸石催化剂对催化裂化柴油、减一线馏分油和常三线馏分油具有较好的非临氢降凝和综合改质性能,生成柴油馏分油的产率较高而气体组分产率较低,气态烃产物中富含低碳烯烃。此外,该催化剂适用于加氢裂化尾油非临氢降凝加工。利用催化裂化柴油、减一线馏分油和加氢裂化尾油非临氢降凝小试评价数据,建立了考虑反应温度和空时影响的非临氢降凝一级表观反应动力学方程,并对生成气体和馏分油的产率进行分析和预测。结果表明,通过对不同柴油馏分油生成物族组成的简化和参数估值,所建模型简单,反应表观活化能和指前因子数量级合理,可有效地预测各族组成的产率。总体上,该组动力学模型对较重组分的产率拟合精度较高,预测能力较强,但对较轻组分的产率拟合精度偏低,预测能力也较弱。更多还原

【Abstract】 The non-hydrodewaxing technique of diesel distillate oils is one of key technologies for the upgrade of diesel products in the current petrochemical field. Non-hydrodewaxing reactions in essence are isomerization and cracking of long paraffinic hydrocarbons in diesel distillate oils. Therefore, an adequate improvement on the isomerization and cracking activities of zeolite-based catalysts can decrease the yield of gaseous hydrocarbons and increase the total liquid yield, particularly, the diesel oil yield. With regard to this scientific proposition the disquisition on the zeolite-based catalysts and relevant catalytic processes has been developed in present work.Zeolites ZSM-35 and MCM-22 with submicron sizes as well as their intergrowth zeolites, were hydrothermally synthesized in the Na2O-SiO2-Al2O3-H2O-CHA (HMI) system, herein the CHA and HMI refer to structure-directing agents of cyclohexylamine and hexamethyleneimine, respectively. Several factors, i.e. the gel composition, crystallization temperature and time, additive sodium dodecyl benzene sulfonate (SDBS), and the rotate speed of autoclavers, were examined, which were found to effect on the crystal phase, morphology and particle size. Crystallinity and phase purity of ZSM-35 and MCM-22 are fine powder, which were obtained with average particle diameters of 590 and 770 nm, respectively under the proper synthesis conditions while samples of MCM-22/ZSM-35 have average particle diameters of 1500-2500 nm.Zeolite such as ZSM-5, MCM-22, MCM-22/ZSM-35, ZSM-35, MOR, p, and Y are respectively as the body of catalyst. Zeolite pore structures impacting on the reactions of 1-hexene as a model compound were investigated by preparing and applying various zeolite catalysts. For the zeolites with 12-membering pores, the mordenite with 1-dimensional channels shows the higher catalytic activity to 1-hexene cracking reaction whereas the hexane isomerization activity is lower. Secondly, zeolites β and Y with 3-dimensional pore structures exhibit higher catalytic activities for both the hexene cracking and polymerization but the activity of hexane isomerization is also lower. However, for the zeolites with 10-membering pore structures, submicron zeolites ZSM-35 and MCM-22 (as well as MCM-22/ZSM-35 intergrowth zeolite) with 2-dimensional channels promotes isomerization reactions of 1-hexene; zeolite ZSM-5 with the known 3-dimensional pore system presents highly initial activities both for the 1-hexene isomerization and cracking reactions. In conclusion, under the reaction condition of temperature 270 ℃, pressure 0.2 MPa, weight hourly space velocity (WHSV) 1.0 h-1 and n(H2)/n(1-C6H12)= 8,1-hexene isomerizes more active in the sequence of ZSM-5, MCM-22, MCM-22/ZSM-35 and ZSM-35. Thus, zeolite ZSM-35 may be a potential active component to improve the catalytic performance of ZSM-5 catalysts in 1-hexene isomerization reactions.The catalyst composed of ZSM-5(99.0%) and ZSM-35(1.0%) were prepared, and the catalytic performance of the composite zeolite catalyst for diesel non-hydrodewaxing processes was evaluated in a 500 mL reactor by feeding different diesel distillate oils; moreover, reaction conditions were optimized and validated further. The evaluation results indicated that the composite catalyst reveals the considerably high catalytic performance for diesel non-hydrodewaxing compared with commercial ZSM-5 catalyst. For the catalytic cracking diesel oil, the optimum reaction conditions were temperature 327℃, pressure 0.2 MPa, WHSV=1.5 h-1, and under the optimum reaction conditions the diesel yield of 94.02% was obtained, diesel condensation point was-21℃ followed a drop of 26℃ as compared with the feedstock. For the diesel distillate oil from third atmospheric side-stream, the optimum reaction conditions:temperature 310℃, pressure 0.2 MPa, WHSV=1.0 h"1, the diesel yield was 94.61%, diesel condensation point arrived at-21℃ and condensation point dropped about 43℃. For the diesel fraction from first vacumm side-stream, the optimum reaction conditions:temperature 353 "C, pressure 0.2 MPa, WHSV=1.5 h-1, diesel yield of 93.92% was obtained followed condensation point at-21 ℃ and a condensation point drop about 30 ℃. For the hydrocracking tail oil, the optimum reaction conditions:temperature 400 ℃, pressure 0.2 MPa, WHSV=1.2 h"1, the yield and condensation point of basic oil separately achieved 93.92% and lower than-20 ℃,and a condensation point drop was more than 52℃.The ZSM-5(99.0%)/ZSM-35(1.0%) catalyst for diesel non-hydrodewaxing processes was evaluated under individual optimum conditions on pilot test scale. The pilot scale testing results demonstrated that the developed zeolite-based catalyst displayed the preferable non-hydrodewaxing performance for the processes of various diesel distillate oils, viz., the catalytic cracking diesel oil, the third atmospheric side-stream diesel oil, and the first vacumm side-stream diesel oil. Considerably high yields of diesel fractions were achieved while quite low yields of gas products were obtained, nevertheless the higher fractions of light olefins were observed in the gaseous hydrocarbons. Furthermore, the corresponding catalyst was substantiated to be a more potential option for non-hydrodewaxing processes of hydrocracking tail oil.Apparent first-order reaction kinetic equations to deal with the non-hydrodewaxing reaction temperature and residence time were established based on the bench test data of the above feedstock oils, and the analysis and prediction for yields of the both gas and distillate oils formed were performed by the first-order kinetic model. It can be see that the kinetic models with magnitude-reasonable apparent activation energies and pre-exponential factors were simple and available for predicting the yields of various gas and distillate oils due to that the simplified group compositions facilitate the parameter estimation. In general, this set of kinetic model equations were confirmed to be more available for the prediction of heavier liquid fractions but the fitting precisions were found lower for the lighter fractions.更多还原