渣油加氢脱残炭的动力学模型研究

根据渣油残炭的构成来源和加氢脱残炭的反应历程．提出了渣油加氢脱残炭的三集总一级反应动力学模型．并建立一集总和二集总加氢脱残炭反应动力学模型与之进行了比较。结果表明．三集总一级加氢脱残炭反应动力学模型的预测精度优于一集总和二集总的反应动力学模型。     

柴油加氢脱芳烃的集总动力学模型的分析研究

为了改善柴油的燃烧性能以及减少尾气污染,要求柴油向低硫、低芳烃、低密度方向发展。开发优良的加氢脱芳烃催化剂对于油品质量升级和清洁燃料生产有着重要意义。芳烃加氢反应动力学研究的主要应用就是指导工艺优化、通过动力学参数的内在联系反映出催化剂的性能,为催化剂的研制提供依据,以及与反应器相结合,为反应器的设计开发提供理论依据。结合 PA/MA 的比例以及原料氮含量对指前因子的关联修正,建立了柴油加氢脱芳烃的集总反应动力学模型,并验证了模型参数和检验模型的合理性。建立的模型可以为不同操作条件下芳烃加氢反应的预测及工艺条件优化提供准确的理论计算数据,同时也可为指导新催化剂的研制提供一定的理论基础。     

煤焦油轻质油加氢制清洁燃料油试验研究

我国石油短缺,对数量可观的煤焦油进行加氢生产燃料油和精细化学品具有重要意义。以煤焦油预处理后的3种轻质馏分油混合油为原料,在固定床加氢装置上进行了轻质油全馏分加氢提质试验研究,考察了反应温度、反应压力、空速和氢油比对原料油脱硫脱氮及芳烃加氢饱和的影响。最后对加氢提质产物油性质进行分析。结果表明,产物氮、硫及芳烃含量均随着反应温度、压力、氢油比的增大而减少,随着空速的增大而增大;在反应温度为360℃,反应压力为16 MPa,液体体积空速为0.25 h~(-1),氢油比为1 800的最优工艺条件下,液体收率达到98.03%。对加氢后全馏分油进行精密蒸馏切割得到170℃的石脑油馏分和170℃的柴油馏分;石脑油馏分20℃密度为776.9 kg/m~3,几乎不含硫、氮,芳烃潜含量67.6%,可以作为优质的催化重整原料;加氢后的柴油馏分不含硫、氮,芳烃含量低,闪点高,凝点低,馏程适宜,可以作为柴油的调和油。     

柴油加氢脱芳烃动力学模型研究进展

简述了国内外在柴油加氢脱芳烃反应动力学模型方面的最新研究进展。指出芳烃的存在会降低柴油的质量,也是对健康的威胁,降低柴油中的芳烃含量十分必要。提出催化加氢是降低柴油中芳烃含量的有效途径。介绍了芳烃加氢反应的动力学和热力学特点。详细叙述了柴油馏分加氢脱芳烃反应的简单集总模型和复杂集总模型。简单集总模型比较简洁实用,但在精确性上略有不足。复杂集总模型计算准确,但对于普通应用而言,复杂且费用不菲,这限制了它的应用。最后总结指出对于新开发的动力学模型,还需要在准确性上下功夫,同时尽可能降低模型开发和使用的成本。这对于模型的推广和应用有着重要的意义。     

煤直接液化柴油深度加氢脱芳烃反应动力学

为了研究煤直接液化柴油加氢脱芳烃反应规律,采用贵金属加氢催化剂在30 mL连续加氢实验装置上对煤直接液化柴油进行了深度加氢实验,考察了不同反应压力6～12 MPa,反应温度80～240℃,体积空速0.4～1.2 h-1条件下煤直接液化柴油芳烃饱和行为。研究表明,在合适的加氢条件下产品油中芳烃质量分数可以降低到0.01%以下。将外扩散传质过程与芳烃加氢反应过程相结合,通过动力学方程推导建立了直接液化柴油芳烃加氢反应动力学模型方程。模型预测结果表明,随着流体空塔流速提高,外扩散有效因子先增大然后趋于1,芳烃转化率呈先增大后趋于不变;反应温度越高,消除外扩散影响所需的流体空塔流速越大。可通过模型预测得到,在消除外扩散影响下,保证直接液化柴油馏分油加氢后芳烃含量低于0.01%所需的反应温度和体积空速。     

渣油加氢装置运行中存在问题及对策

渣油加氢处理的化学反应主要是渣油、催化剂、氢气发生的催化加氢反应,具体反应有加氢脱金属反应(HDM)、加氢脱硫反应(HDS)、加氢脱氮反应(HDN)、加氢脱残炭反应(HDC)和不饱和键的加氢饱和(芳烃、烯烃)反应等。本文主要探讨渣油加氢装置运行中存在的问题及对策。     

反应条件对轻质页岩油加氢脱氮性能的影响

在固定床加氢微反装置上,采用硫化态NiMoW/Al2O3催化剂,以东宁轻质页岩油(＜350℃馏分)为原料,考察反应条件对加氢脱氮性能的影响.结果表明,适当降低反应空速、提高反应压力、提高反应温度均有利于提高催化剂加氢脱氮反应活性,提高产物的质量.在反应温度380℃、反应压力8.0MPa、体积空速0.8h-1、氢/油体积比750∶1的条件下,加氢生成油的硫、氮、芳烃含量均明显降低,石脑油馏分可作为化工轻油,柴油馏分可直接作为清洁柴油调和组分使用.     

工业NiW/Al2O3催化剂上喹啉的加氢脱氮宏观动力学

以喹啉为含氮模型化合物,在高压滴流床反应装置中考察了工业NiW/Al2O3催化剂RN-10上的加氢脱氮动力学规律,研究了反应温度330～420℃、氢分压1.2～5.2MPa、氢油比200～800(v/v)、重量空速(WHSV)20～70 h-1等反应条件对喹啉的加氢脱氮反应结果的影响.结果表明,反应温度对喹啉的脱氮率影响较大,提高反应温度可有效提高喹啉的脱氮率;同时,氢分压也是喹啉加氢脱氮的一个重要的影响因素,但是,当氢分压和氢油比较大时,氢分压和氢油比的变化对喹啉的脱氮率基本无影响.采用修正的n(n＜1)级反应动力学模型对实验数据进行拟合,求得了喹啉加氢脱氮反应的表观活化能为180.4 kJ·mol-1.经检验,模型计算结果与实验结果能较好地吻合.     

煤焦油重质芳烃选择性加氢制单环芳烃

采用固定床反应器对煤焦油中重质芳烃进行选择性加氢,研究反应温度和反应压力对重质芳烃饱和率和单环芳烃选择性的影响。通过制备的4种催化剂进行对比,获得单环芳烃选择性较高的Ni-Mo-P体系催化剂。煤焦油馏分原料的加氢反应结果显示,在反应温度360℃、反应压力6 MPa、空速0.5 h^-1和氢油比800∶1条件下,多环芳烃饱和率为84.2%,单环芳烃选择性为60.4%。通过煤焦油馏分与脱酚余油原料的加氢实验结果对比,脱酚余油中的重质芳烃能获得更高的转化率及单环芳烃选择性。     

加氢脱氮反应与加氢脱氮催化剂的研究进展

介绍石油馏分中主要含氮组分和其结构特性，以及典型含氮化合物的加氢脱氮反应网络、反应机理、反应动力学，阐述了加氢脱氮催化剂改性的不同途径：载体的改性、活性组分和助剂的选择、活化方法的改进等。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.