【作者】 于小桥；

【导师】 沈本贤；

【作者基本信息】 华东理工大学 ， 化学工艺， 2013， 博士

【摘要】 由于我国在α-烯烃生产及聚α-烯烃(PAO)合成技术方面存在明显不足,高档PAO合成润滑油长期依赖进口。随着石油资源的日益紧缺,拓宽蜡裂解制α-烯烃的原料范围,开发适应我国“多煤少油”国情特点的煤蜡裂解a-烯烃合成PAO新工艺技术是缓解我国高档PAO合成润滑油长期依赖进口的迫切要求,这不仅有利于提高煤蜡的附加值,而且对于开发非石油路线制取高性能润滑油基础油新技术更具有重要的意义。本文提出并成功实现了煤蜡裂解α-烯烃合成高性能PAO基础油的工艺技术,通过裂解高熔点煤蜡制备了适宜聚合反应的混合α-烯烃,并采用改进的催化剂合成了性能良好的PAO基础油产品。以煤蜡裂解烯烃为原料的自制PAO产品性能达到优质商业PAO-8产品指标,同时可调合提高石油类基础油的粘度指数等级。论文首先在验证裂解小试实验装置可靠性的基础上,考察了3种不同组成煤蜡的裂解性能及产物分布特点。结果表明,煤蜡1#在预热室温度540℃、裂解温度670℃、停留时间2.5s、水蜡比16%的优化裂解条件下,裂解单程转化率为62.6%,液烯单程收率和选择性分别为43.1%和68.9%,液烯中α-烯烃、二烯烃和正构烷烃含量分别为65.9%、9.7%和18.3%,α-烯烃单程收率和选择性分别为28.4%和45.4%。与54#石油蜡相比,煤蜡原料的裂解单程转化率和α-烯烃单程收率分别可提高约30个和10个百分点,单程转化率的提高能够显著降低原料蜡的回炼量,降低裂解能耗,提高裂解装置的经济性。随后,本文以癸烯-1为原料优选了适宜的催化剂体系及聚合反应条件,在此基础上进行了煤蜡裂解α-烯烃聚合反应效果研究。结果表明,AlCl3/TiCl4双金属催化剂具有良好的低温催化活性。采用AlCl3/TiCl4双金属催化剂,在反应温度80℃、反应时间3h、n(Al)/n(Ti)=5、催化剂质量分数3%的优化条件下,以正构α-烯烃含量分别为65.25%和64.06%的1#和2#煤蜡裂解液烯产物为聚合原料,合成油的收率分别为73.27%和76.21%,合成油40℃运动粘度分别为54.75mm2/s和54.19mm2/s、100℃运动粘度分别为8.77mm2/s和8.68mm2/s、粘度指数分别为138和137、凝点分别为-51℃和-52℃。煤蜡裂解烯烃合成PAO主要由聚合度在3-5的多聚体组成,聚合度大于5的多聚体含量较低,其中280～350℃的馏分含量最高。同时,论文还开展了拟浆态床聚合反应研究,初步实现了α-烯烃连续聚合反应工艺,连续运行时间超过150h。对煤蜡裂解反应机理分析结果表明,煤蜡裂解过程中以烷烃断链和脱氢反应为主,高温、低压、短停留时间有利于提高α-烯烃选择性。基于量子力学第一性原理的裂解反应计算结果,提高裂解温度烯烃更易裂解成二烯烃和烷烃。α-烯烃聚合反应机理分析结果表明,聚合反应过程中同时伴随着叠合、异构化、氢转移以及裂解等反应。以直链为主、碳链上适宜位置具有合适支链的聚合物分子是高性能PAO的理想组分。此外,论文还对煤蜡裂解以及a-烯烃聚合反应的动力学进行了研究。结果表明,将煤蜡裂解视作拟一级串连反应,建立的集总反应动力学模型可以较准确的预测不同反应条件下煤蜡的转化率、液烯和裂解气的收率。反应温度在343K～373K时,模型化合物癸烯-1在AlCl3/TiCl4催化下的聚合反应速率常数在0.165min-1～0.300min-1,动力学方程为：Xm/(1-Xm)=294.71×exp(-21383.61/(RT))to AlCl3/TiCl4催化下的聚合反应速率常数明显大于AlCl3催化剂,采用AlCl3/TiCl4催化剂时聚合反应的反应活化能较AlCl3催化时低3.14kJ/mol, AlCl3/TiCl4的催化活性高于AlCl3催化剂。最后,论文对煤蜡裂解α-烯烃合成PAO的应用情况进行研究。结果表明,精制后的合成PAO产品性能与商业PAO-8产品指标接近；同时,合成PAO产品可作为调合组分以提高石油加工基础油的粘度指数等级,调合30%的自制PAO后,石油加工基础油的粘度指数可从60左右提高到95以上,基础油等级由LVI升级为HVI,凝点由原基础油的-23℃降至-31℃,闪点无明显变化。更多还原

【Abstract】 Due to the lack of advanced technology on a-olefins production and polyalphaolefins (PAO) synthesis, the imported PAO is still the main resource of the high-performance synthetic lubricant. The increasing scarcity status of petroleum resource is pushing us to widen the raw materials for wax cracking plants and develop the proper technology for producing high-performance PAO using a-olefins cracked from coal liquefaction wax in order to meet the national conditions of being rich in coal but lack of petroleum resource and change the situation of import dependency of PAO products. This kind of work, thus, is of great importance not only for improving the value of coal wax but also for coping with the urgent problem of lacking of petroleum resource and producing excellent synthetic lubricant base oil.The synthesis process of PAO base oil using a-olefins cracked from coal liquefaction wax with high melting point was achieved. The mixed a-olefins were produced by cracking coal liquefaction wax and the high-performance PAOs were synthesized using improved catalyst. The properties of synthetic PAO can meet the performance requirement of superior commercial PAO-8products. Meanwhile, the synthetic PAO could be blended with mineral base oil in order to upgrade the viscosity index of the base oil.Firstly, the cracking performances of three kinds of coal liquefaction wax were studied and discussed on a steam cracking experimental equipment based on the reliability testing of this equipment. Under the optimal conditions of preheating temperature of540℃, cracking temperature of670℃, the residence time of2.5s, and the steam ratio of16%, the results indicate that the single pass conversions of waxl#is62.6%, the single pass yield and selectivity of the liquid product are43.1%and68.9%, and the single pass yield and selectivity of a-olefins are28.4%and45.4%. In addition, the contents of a-olefins, diolefins, and alkanes in cracked liquid product are65.9%,9.7%, and18.3%respectively. Compared with54# petroleum wax, the coal liquefaction waxes show around30percentage higher single pass conversion and10percentage higher single pass yield of a-olefins, therefore, will make the cracking plant have lower recycling amount, lower energy consumption, and better economy.Then the oligomerization performance of mixed a-olefins produced from coal liquefaction waxes was investigated while the optimal catalyst system and reaction conditions of decene-1oligomerization were found. The results show that AlCl3/TiCl4catalyst exhibits high catalytic activity under low temperature. Under the oligomerization conditions of catalyst of AICl3/TiCl4, temperature of80℃, time of3h, n(Al)/n(Ti) of5, and catalyst dosage of3%,1#coal wax, which has a normal a-olefins content of65.25%, shows a yield of73.27%,v40of54.75mm2/s, v100of8.77mm2/s, VI of138, and FP of-51℃. As for2#coal wax with a normal a-olefins content of64.06%, the yield, v40, v100, VI, and FP are76.21%,54.19mm2/s,8.68mm2/s,137, and-52℃, respectively. PAO products synthesized from cracked a-olefins is mainly consisted of oligomers with the degree of oligomerization of3-5. Moreover, the fraction with distillation range of280～350℃has the highest content in PAO products. Besides, the pseudo slurry bed oligomerization process was investigated and the synthesis of PAO can be performed continuously for more than150h at the present pseudo slurry bed reactor.The analysis results of cracking mechanism indicate that the main cracking reactions are the chain scission reactions and dehydrogenation reactions of alkane molecules. A high temperature, low partial pressure of alkane, and short retention time are beneficial to the selectivity of a-olefins. The calculation results based on quantum mechanical method show that olefins can crack into diolefins more easily at higher temperature. The mechanism of a-olefins oligomerization is also discussed and the results indicate that the oligomerization reactions occur along with isomerization, hydrogen transfer, and cracking reactions. Furthermore, the oligomers, which have one linear main chain and proper branches, are the excellent components of high performance PAO.In addition, the kinetics of the coal wax cracking and oligomerization of a-olefins were studied. A lumping kinetic model of coal wax cracking was developed based on the assumption of first order consecutive reaction. The kinetic model exhibits high accuracy for predicting the conversion of coal wax and the yields of liquid and gas products. The rate constants of decence-1oligomerization at the temperature from343K to373K with AlCl3/TiCl4catalyst are found in the range of0.165min-1and0.300min-1. The kinetic model can be expressed as:Xm/(1-Xm)=294.71×exp(-21383.61/(RT))t. AlCl3/TiCl4catalyst gives higher catalytic reaction rate constants and3.14kJ/mol lower activation energy as compared to AlCl3catalyst, suggesting higher catalytic activity than AlCl3catalyst.In the end, the application performance of synthesized PAO was researched and discussed. It is found that the refined PAO product exhibits the similar properties to the commercial PAO-8product. Meanwhile, the synthesized PAO can be blended into petroleum base oil to upgrade the viscosity index of the base oil. The viscosity index of petroleum base oil can be improved from60to above95by blending30%mass fraction of synthesized PAO. As a result, the blended petroleum base oil was upgraded from LVI to HVI. As compared to the petroleum base oil, the blended base oil shows a lower freezing point and similar flash point.更多还原