聚丙烯酸十八酯-乙酸乙烯酯梳状二元共聚物降凝剂对含蜡原油结晶特性与流变性的影响

在合成聚丙烯酸十八酯(POA)梳状均聚物和聚丙烯酸十八酯-乙酸乙烯酯(POA-VA)系列梳状二元共聚物的基础上,通过凝点测量、流变实验、差示扫描量热(DSC)分析及偏光显微镜观察等手段研究了POA与POA-VA对长庆含蜡原油结晶特性与流变性的影响.实验结果表明VA基团的引入调控了POA降凝剂对含蜡原油的作用效果.当OA与VA单体摩尔比为3∶1时,POA-VA对含蜡原油的流变改善效果最好,在降凝剂400 mg/kg剂量下可以降低凝点22℃,平均降黏率为51.45%;而单体摩尔比升高或降低均会使POA-VA对含蜡原油的流变改善效果变差.另外,从POA-VA分子的结晶放热特性和蜡晶微观形貌分析角度,探讨了VA含量对POA-VA作用性能的影响规律和机理.     

降凝剂对蜡油中蜡析出与溶解影响的物理化学研究

用DSC热分析仪研究了合成蜡油的加热与冷却过程,测定了蜡油在不同蜡浓度下,添加降凝剂前后的平衡蜡溶点和析蜡点以及溶解度和饱和度,并进行了热力学分析.结果表明,含蜡油的平衡蜡溶点高于平衡析蜡点,降凝剂使平衡蜡溶点进一步升高,析蜡点进一步降低,导致含蜡油凝点较大幅度降低.在实验浓度和温度范围内,该过程符合Van′tHoff方程,降凝剂使蜡的溶解焓和溶解熵增大,析出焓和析出熵减少.降凝剂提高了蜡晶析出的临界半径,增大了成核位垒,使蜡晶析出困难.     

含蜡原油降凝剂与石蜡作用机理的研究进展与探讨

高分子降凝剂产品已广泛应用于原油的开采和输送工艺中,但是,对降凝剂降凝机理认识的不足制约了降凝剂的开发和应用.降凝剂与油品中石蜡的相互作用决定其降凝机理.本文综述了近年来人们在研究降凝剂与石蜡作用机理方面所使用的研究方法和所取得的进展,并深入探讨了降凝剂与石蜡的具体作用方式.对于含蜡原油,降凝剂主要通过与石蜡的共晶、吸附作用使蜡晶结构更紧凑,并促进小蜡晶聚集成较大尺寸的聚集体,从而大大降低蜡.油界面积,破坏蜡晶三维网络的形成,宏观上表现为原油凝点降低,低温流动性改善.     

柴油降凝剂的合成及性能研究

合成了新型聚合物型柴油降凝剂,并采用红外光谱对聚合物进行了表征。X射线衍射技术对不同降凝剂的结晶性能分析表明,聚合物的结晶性能差别很大,结晶度不同,蜡晶分散效果不同。同时发现,当两者结晶性能状态匹配时蜡晶分散效果变好,降凝性能最佳,并由柴油体系降凝性能证实。     

正硅酸乙酯对高电压镍锰酸锂基全电池电化学性能的影响

为了提高镍锰酸锂全电池的电化学性能,本文采用物理混合的方法在负极浆料中加入正硅酸乙酯(TEOS),并按m(TEOS)∶m(石墨)=0∶100、5∶100、10∶100、16∶100、20∶100的比例进行搅拌混合。 以镍锰酸锂为正极,石墨为负极,组装成502030型软包装锂离子电池,并对该电池进行恒流充放电和内阻等测试。 测试结果显示,0TEOS(m(TEOS)∶m(石墨)=0∶100)样品的电池内阻为159 mΩ,循环200圈后,容量保持率为52.6%,放电比容量为46 mA·h/g;16TEOS(m(TEOS)∶m(石墨)=16∶100)样品的电池为105 mΩ,65.7%和62.9 mA·h/g。 实验结果表明:通过物理混合的方法在负极浆料中加入TEOS,有利于在负极表面形成结构稳定的人工固体电解质膜(SEI膜),提高镍锰酸锂材料的循环和倍率性能。     

含芳香基团的梳状聚合物型降凝剂与沥青质协同改善合成蜡油的流变性

采用流变学实验、 差示扫描量热(DSC)分析、 显微观察及沥青质沉淀实验研究了聚丙烯酸十八酯-马来酸酐(POM)、 聚丙烯酸十八酯-马来酸酐-苯胺(POMA)及聚丙烯酸十八酯-马来酸酐-萘胺(POMN)梳状聚合物对合成蜡油的流变性能的影响规律. 实验结果表明, 这3种梳状聚合物降凝剂均能在一定程度上改善不含沥青质合成蜡油(MO-1)的低温流变性, 其中POM对MO-1蜡油的流变性改善效果最佳. 添加500 mg/kg POM后, MO-1的凝点从29 ℃降至23 ℃, 屈服值从627.20 Pa降至83.35 Pa. 而POM, POMA和POMN可以显著改善含0.3%(质量分数)沥青质的合成蜡油(MO-2)的低温流变性, 且添加500 mg/kg POMA后MO-2蜡油的流变改善效果最佳: 凝点降至3 ℃, 屈服值降至1.27 Pa. 可见, 本文制备的梳状聚合物降凝剂均能与沥青质协同改善MO-2蜡油的流变性, 并且向POM中引入芳香基团能进一步促进沥青质与降凝剂分子的相互作用, 进而增强梳状聚合物降凝剂与沥青质的协同作用.     

十二烷基聚氧乙烯(n)醚与牛血清白蛋白的团簇化热力学模型

用表面张力和稳态荧光猝灭技术研究非离子表面活性剂十二烷基聚氧乙烯(n)醚(AEO_n)与牛血清白蛋白(BSA)的团簇化体系,根据质量作用定律建立AEO_n与BSA的团簇化热力学模型.从ΔH°>0,ΔS°>0及ΔG°＜0可以推知,AEO_n束缚胶束与BSA形成软物质团簇是熵驱动的超分子自组装过程,其间的超分子作用力以疏水作用为主.团簇化过程的(ΔG°)_clu与表面活性剂自由胶束化过程的(ΔG°)_mic皆小于零,且c₁＜cmc,可以圆满解释在团簇化体系中表面活性剂形成束缚胶束并与大分子经超分子自组装形成软团簇在先,而表面活性剂分子自组装形成自由胶束在后的实验事实.     

PP/EVA/OMMT纳米复合材料及其阻燃材料的动态燃烧行为

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/乙烯-醋酸乙烯酯共聚物(EVA)/有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/EVA/OMMT/氢氧化铝(ATH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加5%(质量分数)OMMT可以提高PP/EVA复合材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且OMMT与无卤复配阻燃剂之间可产生阻燃协同作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。     

巯基膨润土的制备工艺及性能

为了简化巯基膨润土(Bent-SH)的制备工艺、降低制备成本以便于实际应用,用3-巯丙基三甲氧基硅烷(MPS)与硅酸钠协同改性膨润土(Bent)。 优化了Bent-SH的工艺条件、表征了Bent-SH的结构、测定了Bent-SH的性能。 最佳制备工艺为:Bent与MPS的用量比为1∶0.05(g/mL);m(Na₂SiO₃)∶m(Bent)=7.0∶100;固液比为1∶20(g/mL);改性悬浮液的最佳pH值为8.0～10.0;改性时间为5～6 h,反应温度为室温。 Bent-SH较Bent胶质价、膨胀倍和阳离子交换容量均有所下降,但Bent-SH对镉的饱和吸附容量为20.86 mg/g,比Bent提高了20多倍。 硅酸钠和MPS协同改性没有改变Bent层状结构,而显著增强了Bent-SH的疏水性,分散性及对镉的吸附容量和吸附选择性。 Bent-SH是一种具有应用前景的重金属污染土壤的钝化剂。     

国内外常用降凝剂成分分析及性能表征

采用红外光谱法、凝胶色谱法、超导核磁共振波谱法、皂化滴定法以及气相色谱-质谱法等对国内外10种常用柴油降凝剂进行了成分分析,以寻找其成分对降凝剂性能的影响。结果表明:10种柴油降凝剂均属乙烯-乙酸乙烯酯聚合型降凝剂,样品聚合物部分相对分子质量较低,乙酸乙烯酯聚合物的质量分数一般在27%～37%之间,样品溶剂为重芳烃、以C₁₀为主的烷烃或者它们的混合物。其中,国外产品的相对分子质量较高（M_r>3 700）,乙酸乙烯酯聚合物质量分数大于30%,且溶剂添加了少量含氮类分散剂。     

Effect of modified nano-silica/EVA on flow behavior and wax crystallization of model oils with different wax contents

The nano-hybrid pour-point depressant (PPD) was prepared with organically modified nano-silica covering in EVA. The effects of modified nano-silica/EVA on the flow behavior and wax crystallization of model oils with different wax contents were evaluated. Compared with pure EVA and nano-silica/EVA, modified nano-silica/EVA exhibited a better effect, when doped with 500?ppm, the pour point of the model oil containing 20?wt% wax was reduced from 33°C to 0°C. However, it is noteworthy that pour point cannot accurately reflect the effect of YSiO2/EVA as cold flow improver for a high wax content. The crystal morphology and crystallization behavior of the model oils at low temperature were also observed using polarizing optical microscopy (POM). The results indicated that modified nano-silica/EVA can reduce the size of the wax crystals and disperse the wax crystals by heterogeneous nucleation.     

Submicron carbon-based hybrid nano-pour-point depressant with outstanding pour point depressant and excellent viscosity depressant

We have investigated the effective utilization potential of carbon nanomaterials in the field of pour point depressants, and reported three kind of carbon-based hybrid nano-pour-point depressants with different dimensions. In this paper, poly-α-olefins-acrylate high-carbon ester pour point depressant (PAA-18) was prepared by esterification and polymerization as the basic pour point depressant. Then, the basic pour point depressant PAA18 was modified by solvothermal method with graphene oxide (GO), carbon nanospheres (Cna) and carbon nanotubes (OCNTs). The morphology and structure of the composites were analyzed by SEM, FTIR and XRD. The results showed that PAA18 was successfully in situ polymerized on GO, Cna and OCNTs. We took the simulated oil as the experimental object, and evaluated its pour point, rheological properties and wax crystal morphology, and achieved excellent results. In the three carbon-based hybrid nano-pour-point depressants with different carbon contents, the oxidation carbon nanotubes composite pour point depressant (PAA18-1 % OCNTs) with carbon content of 1 % had the best pour point and viscosity reduction effect when the dosage was 1250 ppm, which could make the pour point of the simulated oil containing wax decrease by 16 °C. PAA18-1 % OCNTs reduced the pour point by 5 °C more than PAA18. This paper provides reference for the application of carbon nanomaterials in the field of pour point depressant.     

Advances in the research of polymeric pour point depressant for waxy crude oil

In the pipeline transportation of waxy crude oil when the temperature of the waxy crude oil drops lower than the wax appearance temperature (WAT), wax precipitates continuously from oil phase, which brings a series of negative impacts on pipeline performance and even causes complete blockage under severe conditions in recent decades, polymeric pour point depressants have a very important practical application in depressing the pour point and improving the fluidity of waxy crude oil, thus reducing the cost of waxy crude oil pipeline transportation. The most commonly used types of the polymeric pour point depressants include ethylene-vinyl acetate (EVA) copolymers, comb copolymers, and nano-hybrid pour point depressants. In this paper, the structural character, interactive types, and the action mechanism of the polymeric pour point depressants are reviewed with their application and research progress introduced.     

Effect of nanocomposite of attapulgite/EVA on flow behavior and wax crystallization of model oil

Nanocomposites of attapulgite (ATT)/ethylene vinyl acetate copolymer (EVA) were prepared with organically modified ATT covering in EVA. Organically modified ATT was prepared using KH550 and organic acid. The effect of nano-hybrid on the flow behavior of model oil containing 15?wt% wax was evaluated. The wax crystallization and crystal morphology of the model oil at low temperature were observed by polarizing optical microscopy (POM). The results indicated that the nano-hybrid with long-chain organic acid-modified ATT exhibited a better effect compared with the nano-hybrid with short-chain organic acid-modified ATT, pure EVA. In addition, it is interesting to note that EVA (VA?=?32%)/stearic acid-modified ATT composite polymeric pour-point depressant (PPD) S-AtPPD(32) provided better cold-flow improvement for the model oil than EVA (VA?=?32%)-modified nano-SiO₂ composite PPD N-SiPPD (32) with a low dose, which resulted in a regular, bar-shaped, and uniform arrangement of wax morphologies. The pour point of the model oil was reduced from 30°C to ?1°C when doped at 200?ppm S-AtPPD(32).     

Study on the Inherent Factors Affecting the Modification Effect of EVA on Waxy Crude Oils and the Mechanism of Pour Point Depression

The Ar-Sai waxy crude oils were taken as the research objects, and the viscosity reduction rates and the condensation point reduction rates were regarded as the evaluation indexes, the impacts of components content of the crude oils and carbon number distribution of waxes on the modification effect of EVA-type pour point depressant (PPD) were analyzed by using gray correlation analysis method. The oil wax was acquired by applying the extraction and separation techniques initially, then the structures and the lattice parameters of wax crystals before and after adding the PPD were studied by polarized light microscopy observation and x-ray diffraction techniques, the mechanism of pour point depression was discussed at last. The results indicate that wax content and the low carbon number wax have significant influences on the modification effect of PPD, while the impact of high carbon number wax is relatively small. Co-crystallization is the main mechanism of pour point depression, nevertheless, the impacts of the asphaltenes, resins, solid particles, and light components of the crude oils on the modification effect of the PPD cannot be ignored.     

Effect of gemini surfactant additives on pour point depressant of crude oil

Efficiencies of cationic gemini surfactant additives in improving the pour point depressant of crude oil were investigated. The length of alkyl chain is a major factor affecting the improvement of the pour point depression. The adsorption behavior of these gemini surfactants at air/solution and oil/solution interfaces were investigated by measuring the surface tension and interfacial tension as functions of concentration. It is found that there is a good relation between surface properties especially interfacial tension of the gemini surfactants and their efficiency in depressing the pour point. Also, the surface parameters and free energies of micellization and adsorption confirm the decreasing and improving of pour point depression. Crystallization study in crude oil revealed the relationship between the structure and activity of gemini surfactant additives. It is found that the x-ray diffraction patterns of waxes with additives are remarkably different from those without additives. The mechanism of the depressants action has been suggested according the adsorption of each additive. Adsorption of the additive on the surface of the wax particles inhibits their growth and alters the crystal habits through micelle core. Pretreatment of the crude oil with pour point depressants has received the greatest acceptance due to its simplicity and economy.     

新型聚丙烯酸酯类柴油降凝剂分子模型的建立及验证

在前期工作得出的正构烷烃含量与浊点、冷滤点、凝点的定量关系模型基础上，选择柴油降凝剂的基团对柴油降凝剂分子结构进行了设计，得出了设计模型。结果表明，将含氮基团引入柴油降凝剂可以显著提高柴油降凝剂的性能。根据设计模型合成了一系列聚丙烯酸单酯和混合酯柴油降凝剂，并通过对柴油降凝剂的性能测试结果和自行设计的计算程序对设计模型进行了验证，结果表明，从柴油正构烷烃含量对柴油降凝剂的配比进行设计是可行的。