【作者】 熊中强；

【导师】 米镇涛；

【作者基本信息】 天津大学 ， 化学工艺， 2005， 博士

【摘要】 本文以双环戊二烯（DCPD）为原料,通过双烯加成、分离、加氢反应得到目的产物——新型高密度液体燃料四氢三环戊二烯（THTCPD）,主要研究内容包括:1.三环戊二烯（TCPD）的合成采用两种方式对TCPD的合成进行了研究:DCPD直接热聚法、DCPD与环戊二烯（CPD）双烯加成法。其中双烯加成法通过将裂解、加成反应分步进行,解决了直接热聚法中裂解、加成反应温度不匹配问题,提高了加成反应转化率、选择性。产物TCPD的分析结果表明仅有两种TCPD异构体生成,反应温度、压力对双烯加成有较大影响,温度高反应加快、TCPD收率升高,但过高的温度导致产物中高聚物（四环戊二烯、五环戊二烯等）生成,反应选择性降低,由于高聚物难于分离且其加氢产物不适合作为液体燃料,因而加成反应过程中须控制反应温度以抑制高聚物的生成;升高压力反应速度加快,TCPD收率提高,可避免高温条件下反应时高聚物的生成;TCPD最佳合成条件为高压、低温。实验测定Diels-Alder反应动力学方程为:利用材料模拟软件Materials Studio 3.0对反应原料、产物的极性进行模拟计算,结果表明各组分极性:exo-exo-endo-TCPD>endo-exo-endo-TCPD>DCPD >CPD。在模拟计算基础之上,选择苯甲醇、环己酮、甲苯及十氢萘四种溶剂进行Diels-Alder反应的溶剂效应研究,考察温度、压力变化对反应速度、产物立体选择性的影响。结果表明,随着所使用溶剂极性增强,Diels-Alder反应速度加快、产物TCPD立体选择性降低。不同溶剂的使用对Diels-Alder反应的影响在于不同反应历程中所形成的中间过渡态及其产物性质不同,强极性溶剂中反应时生成极性更强的过渡态所需活化能更小,从而导致反应立体选择性变化;同样,由于TCPD两种异构体的极性均高于反应原料,故溶剂极性增强使得反应速率增加。根据溶剂效应影响及其产物结构分析可知,endo-exo-endo-TCPD为产物中的主要成分。实验测定使用不同溶剂时Diels-Alder反应动力学方程分别如下所示。2. Pd-B/γ-Al₂O₃非晶态合金催化剂的制备采用化学还原法以KBH4为还原剂制备了负载型Pd-B/γ-Al₂O₃非晶态合金催化剂,在XRD表征证实所得催化剂的结构为非晶态基础之上,以TCPD加氢为探针反应,深入考察了制备过程中催化剂前驱体焙烧温度、还原剂用量与滴加速度、还原温度对催化剂结构、活性的影响,并同300°C条件H2还原所得Pd/γ-Al₂O₃催化剂进行对比,结果表明非晶态合金催化剂活性更高。催化剂制备过程中,前驱体焙烧温度主要影响活性中心Pd与载体之间结合力,焙烧温度低、催化剂活性中心在还原过程中流失导致活性下降,300°C条件焙烧可保证活性中心无流失;还原剂用量主要影响催化剂活性中心Pd的还原度,采用1倍（KBH4:Pd=1:1,mol）还原剂时催化剂还原不完全导致活性低,而3倍以上还原剂用量可保证完全还原;还原剂滴加速度及其还原温度对还原度没有影响,主要影响催化剂结构从而影响其活性。实验范围内Pd-B/γ-Al₂O₃非晶态合金催化剂最佳制备条件为:前驱体焙烧温度300°C、还原剂0.2mol/L KBH4、使用量KBH4:Pd=3:1（mol）、滴加速度0.5mL/min、还原温度0°C。在N2气流中经过150°C⁶00°C条件热处理后,Pd-B/γ-Al₂O₃非晶态合金催化剂不同程度的晶化、活性降低,且热处理温度越高、晶化度越高、活性降低越多。不同晶化度催化剂的表征结果表明,其活性降低原因在于催化剂晶化后活性中心分散度降低、颗粒增大。非晶态合金催化剂晶化过程的原位分析结果表明,在热处理温度低于150°C条件下其结构基本保持稳定,而高于450°C条件下热处理后晶化度大于90%,600°C以上热处理后完全晶化。3. TCPD加氢反应与产物性能研究对TCPD加氢反应过程进行研究,利用1H-NMR对TCPD加氢反应原料、中间产物、产物进行研究,结果表明,同环戊烯基双键相比,TCPD分子中降冰片烯基双键更容易加氢,反应的中间产物主要为14,15-DHTCPD,确定了连串反应模式。采用釜式反应器,在排除内外扩散的条件下测定了以Pd-B/γ-Al₂O₃非晶态合金为催化剂的TCPD加氢反应本征动力学,实验条件范围为:温度110°C¹40°C、氢压2.0MPa³.5MPa。实验提出了Eley-Rideal型动力学方程,通过实验值优化计算得到动力学参数,两步加氢反应的活化能分别为11.1141kJ/mol、34.7217kJ/mol,计算值与实验值相对平均偏差小于13%。产物THTCPD性质测定结果表明,其常温条件下为液体,密度1.0283g/cm3 （20°C）,但粘度高,不能单独作为燃料使用。THTCPD与JP-10混配燃料拥有较好的性质,不仅密度提高且拥有很好的低温性能。更多还原

【Abstract】 This dissertation is concerned with the approaches to a new high density liquid fuel, tetrahydrotricyclopentadiene （THTCPD）, which can be synthesized with dicyclopentadiene （DCPD） as raw materials by three steps: Diels-Alder reaction, separation and hydrogenation. The main points of the paper are listed as follows.1. Synthesis of tricyclopentadiene （TCPD）Two methods of polymerization were analyzed in the synthesis of TCPD: thermal polymerization of DCPD, Diels-Alder reaction of DCPD and cyclopentadiene （CPD）. The results show that the latter was much better then the former. By separating the cracking and addition procedure, the contradiction of two different reaction temperatures was successfully solved. The conversion of DCPD, yield of TCPD and reaction selectivity were much higher then the thermal polymerization. GC analysis results show that only two TCPD isomers were founded in the product. Temperature and pressure has considerable effect on the Diels-Alder reaction. Higher temperature and pressure can speed up the reaction, but excessively high temperature and pressure may lead to the formation of higher oligomers of CPD, such as tetracyclopentadiene （TeCPD）, pentacyclopentadiene （PCPD）. The higher oligomers were very difficult to be separated from TCPD and the properties of their hydrogenation products were not suitable for liquid fuels, so the reaction temperature and pressure were controlled to prevent the higher oligomers present in the product. The best reaction condition is high pressure and low temperature. Kinetics of the Diels-Alder reaction was measured by experiment with the power exponent equation as following.Solvent effect on the Diels-Alder reaction was analyzed with four different kinds of solvents: benzyl alcohol, cyclohexanone, toluent and decalin. The results show that the rate of the Diels-Alder reaction increased in more polar solvents and stereoselectivity of TCPD decreased. The polarity of DCPD, CPD and TCPD was calculated by Materials Studio 3.0 and the result was: exo-exo-endo-TCPD> endo-exo-endo-TCPD>DCPD>CPD. The effect of solvent on the rate of the Diels-Alder reaction and stereoselectivity can be commonly explained by assuming atransition-state model. They can be related to the free energy difference between the transition states with different solvent. Taking in isolation of dipole, the transition state leading to the greater polarity product will have lower activation energy in greater polarity solvent. Similarly, the polarity of both TCPD isomers is greater then the reagents, this implies an overall rate increase in polar solvents. From these results we know that the main product of TCPD is endo-exo-endo-TCPD. Reaction kinetics with different solvent were as follow.2. Pd-B/γ-Al₂O₃ amorphous alloy catalystThe Pd-B/γ-Al₂O₃ amorphous alloy catalyst was prepared by regular impregnation following the chemical reduction with KBH4 aqueous solution. Its amorphous structure was confirmed by X-ray diffraction. The activity of the as-prepared catalyst was measured by using TCPD hydrogenation as a probe and compared with those of corresponding Pd/γ-Al₂O₃ catalyst obtained by H2 reduction at 300°C. The effects of catalyst precursor calcination temperature, reductant amount, adding speedand and reducing temperature on the catalyst structure and its catalytic activity were also under investigation. Experiment results show that Pd-B/γ-Al₂O₃ amorphous alloy catalyst exhibited higher activity than the corresponding H2 reduced Pd/γ-Al₂O₃. The optimum preparation condition is: calcination temperature 300°C, KBH4 aqueous solution 0.2mol/L, KBH4:Pd2+=3:1（mol）, adding speed 0.5mL/min and reducing temperature 0°C.When the as-prepared Pd-B/γ-Al₂O₃ amorphous alloy catalyst was pretreated at the temperature from 150°C to 600°C in N2 flow, the activity of the catalyst decreased with the increase of temperature. According to various characterizations, such as XRD, SEM, TEM, XPS, H2-chemisorption, H2-TPD, DSC and In-suit XRD, it was concluded that the effect of the pretreatment temperature on the activity should mainly attribute to the surface structure changes which was caused by the transformation from amorphous structure to crystalline structure. In-suit XRDanalysis of the catalyst show that its structure remained well after 150°C thermal treatment, the crystalline degree reaches 90% after 450°C thermal treatment and totally crystallized at 600°C.3. TCPD hydrogenation and product propertyHydrogenation material, intermediate product and product were characterized by ¹H-NMR. The results show that the two C=C double bond has different reactive behavior. Compared with the double bond of cyclopentene ring, the double bond of the norbornene ring has much more lower activation energy in the hydrogenation and the main intermediate product is 14,15-DHTCPD.The intrinsic kinetics of TCPD hydrogenation to THDCPD over Pd-B/γ-Al₂O₃ amorphous alloy catalyst was investigated using stirred kettle reactors in the absence of transport limitations over the ranges of temperature 110°C¹40°C and hydrogen pressure 2.0MPa³.5MPa. An Eley-Rideal equation model was proposed to describe the experimental data and its kinetic parameters were also regressed by comparing the calculated and experimental concentrations profiles of reactants and produces. It was found that the theoretical prediction on the concentration by the proposed model agreed well with the experimental data, the average relative error is less than 13%. The activation energy for the first and second reaction step is 11.1141kJ/mol and 34.7217kJ/mol.The characterization results show that THTCPD is liquid at room temperature with density 1.0283g/cm3 at 20°C. The mixture of THTCPD and JP-10 can be used as high density liquid fuel with good low temperature character especially for its low freezing point.更多还原