Additives from aromatic extracts

Aromatic extract residues, as by-products, are accumulated in local refineries through the refining of lubricating oils. These residues are dealt with as low economic value products, even their disposal imposes serious problems to the refineries. Therefore, the present work is aimed at upgrading these residues by using them to synthesis some different petroleum additives, e. g. antioxidants, ashless dispersant additives, pour point depressants and flow improvers for crankcase lubricating oils and fuels. Antioxidants are synthesised by reacting mono-aromatics with phosphorus pentasulphide (P₂S₅) in the presence of zince oxide (ZnO). Ashless dispersant additives are synthesised by reacting alkylated mono-aromatics (using chlorinated paraffin wax as alkylating agent) with formaldehyde solution (37%) in the presence of polyisobutylene succinimide. Pour point depressants and flow improvers are synthesised by acylating di-aromatics via a Friedel-Crafts' reaction. Comparative evaluation of the performance of the synthesised products with commercial additives showed their good efficiency.     

Polymeric structures as cold flow improvers for waxy residual fuel oil

Acrylic and methacrylic acids were esterified with dodecyl, hexadecyl and NAFOL 20⁺ (C_av = 21) alcohols. The monomers thus prepared were copolymerized with C₁₈ α-olefin at different molar ratios. The copolymers were purified, characterized and then assessed as cold flow improvers for a high-pour waxy residual fuel oil (RFO) by pour point and rheological measurements. The asphaltene, resin and wax contents of the RFO as well as the carbon number distribution of the wax fraction were determined. The results show that only the polymeric structures with long side chains of NAFOL 20⁺ have the potential to decrease the pour point and improve the rheological properties of the fuel oil. The storage stability of the treated RFO is good up to 3 days but then diminishes steadily. The effectiveness of the prepared additives is discussed on the basis of structure in relation to the fuel oil composition.     

Synthesis of polymeric pour point depressants for Nada crude oil (Gujarat,India) and its impact on oil rheology

Five flow improvers have been synthesized to study rheological properties of Nada crude oil (Gujarat, India). Anhydride copolymers were prepared making use of the copolymerization of acrylates of different alkyls with maleic anhydride and the Poly (n-alkyl acrylates-co-N-hexadecylmaleimide) were prepared by the reaction of copolymer with hexadecylamine. The additives were purified and characterized by FTIR, GPC. The prepared polymeric additives shows dual function both as wax dispersants and flow improvers and all of them acts as good pour point depressants. Yield stress and the viscosity of the crude oil at different temperatures and concentrations of additives were evaluated by zero friction advanced rheometer AR-500 of TA instrument. Comparison of morphologies and structures of wax crystals or aggregates in waxy crude oils beneficiated with and without a PPD was also done by micro photographic studies which show the modification in wax crystal morphology due to additives.     

Study on the relationship between the structure and activities of alkyl methacrylate–maleic anhydride polymers as cold flow improvers in diesel fuels

In order to find efficient cold flow improvers for diesel fuels derived from crude oil, copolymers (R¹MC–MA) were prepared making use of the copolymerization of methacrylate (R¹MC) of various alkyls with maleic anhydride (MA), and terpolymers (R¹MC–MA–R²MC) were prepared by the reaction of long-chain alkyl methacrylate (R¹MC), maleic anhydride (MA), and short alkyl methacrylate (R²MC). The additives were purified and characterized by IR, ¹H–NMR, and GPC. The activities of the synthetic products as the cold flow improvers in two diesel fuels were investigated. The results indicate that: (1) the alkyl chain length of R¹ in R¹MC–MA copolymers significantly affects the solid point depressing performance. When the long-chain alkyl R¹ is n–C₁₄H₂₉– and the reaction material molar ratio (R¹MC/MA) is 1:2, the C₁₄MC–2MA possesses the best ΔSP property; (2) the (C₁₄MC–MA–R²MC) terpolymers all demonstrate excellent solid point depression properties when the short-chain alkyl R² varies from CH₃– to n–C₈H₁₇–; (3) however, all of the tested copolymers and terpolymers do not demonstrate necessary cold filter plugging point depression performance.     

Polymeric additives for improving the flow properties and viscosity index of lubricating oils

Four sets of copolymeric additives were synthesized via copolymerization of dialkyl fumarates and dialkyl maleates with vinyl acetate (VAc) and vinylpyrrolidone (VP) monomers. The dialkyl esters were prepared by the esterification of maleic and fumaric acids with a series of n-alkanol having an increasing number of carbon atoms to produce two groups of diesters. The completion of the esterification reaction was confirmed by spectroscopic analysis. The molecular weights of the prepared esters and copolymers were determined and the influences of different parameters on the molecular weight of the produced copolymers were discussed. The efficiency of the prepared copolymers as viscosity index and flow improvers (pour point depressants) was investigated. It has been found that the dialkyl ester/VP copolymers are more efficient as viscosity index improvers than the dialkyl ester/VAc copolymers. On the other hand, it has been found that the copolymers based on didodecyl fumarate/VAc are the most effective pour point depressants.     

Co-adsorption behaviors of asphaltenes and different flow improvers and their impacts on the interfacial viscoelasticity

Commonly used flow improvers in oilfields, such as ethylene–vinyl acetate copolymer (EVA), poly(octadecyl acrylate) (POA), and polymethylsilsesquioxane (PMSQ) are proven to be effective to enhance the flowability of crude oil. However, the addition of these flow improvers may change the stability of the emulsion and make the crude oil treatment process challenging. In this research, the impacts of different flow improvers on the interfacial properties of the emulsions containing asphaltenes are systematically investigated. The co-adsorption behaviors of the flow improvers and asphaltenes are analyzed through dynamic interfacial tension (DIFT). The rheological properties of the interfacial layer after the adsorption are explored via dilational viscoelasticity. Significant difference is observed in the structural properties of the interface adsorbed by different flow improvers, which is attributed to different interactions between the flow improvers and asphaltenes. To investigate these interactions, conductivity, asphaltenes precipitation, dynamic light scattering (DLS), and contact angle experiments are conducted systematically. Results show that EVA and POA can alter the interfacial properties by changing the asphaltene dispersion state. The interaction between EVA and asphaltenes is stronger than that between POA and asphaltenes due to the difference in molecular structures. Unlike EVA and POA, the change of interfacial property with the addition of PMSQ is attributed to the partial adsorption of asphaltenes on PMSQ.     

Zum viskositäts-temperatur-verhalten organischer flüssigkeiten nach dotierung mit poly-N-butylmethacrylat als viskositäts-index-verbesserer

In tribology macromolecules in solution are used as viscosity index improvers. Thereby a smaller dependency of viscosity on temperature is obtained. Two reasons are mainly responsible for this effect:

• 1 Transition to a basal fluid of relative low viscosity with a low absolute value of temperature coefficient of viscosity and consequently with a low value of heat of activation for viscous flow Aη. Raising of viscosity into the operating range by addition of polymers.
• 2 Expansion of the dissolved polymers with increasing temperature (coil contraction is also possible).

Investigations showed that in the system poly(n-butylmethacrylat) (PBMA)/isopropanol (poor solvent) A_η decreases with increasing concentrations of PBMA. The intrinsic viscosity [η] as a measure for coil expansion passes through a maximum with rising temperature. On the other hand A_η increases slightly with increasing PBMA concentrations, if chloroform (a good solvent) is used. This system does not show an extremum of [η] in temperature dependence in the given range.     

Effect of wax inhibitors on pour point and rheological properties of Iranian waxy crude oil

A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of waxy crude oil. Flow improvers are used extensively to increase the mobility of crude oil. In this study, the influence of the ethylene-vinyl acetate copolymer (EVA), as flow improver, with different ranges of molecular weight on the viscosity and pour point of five Iranian waxy crude oils was evaluated. Five types of Iranian waxy crude oil were selected based on their similar wax (> 10%) but different asphaltene contents. Also, the effect of asphaltene content on the performance of this flow improver was studied. The rheological behavior of these crude oils, with middle range API gravity, in the absence/presence of flow improver was studied. The rheological data cover the temperature range of 5 to 40 °C. The results indicated that the performance of flow improver was dependent on the molecular weight and the asphaltene content. For crude oil with low asphaltene, higher molecular weight flow improvers are the best additive and lower molecular weight flow improvers showed good efficiency for crude oil with high asphaltene content. Addition of small quantities of asphaltene solvents such as xylene (1 wt.%), alone or in combination with flow improver, can improve viscosity of crude oil with high asphaltene content.     

柴油低温流动改进剂感受性的影响因素

选择南阳柴油以及T1804、XLT-1808(103#)、PAE等几种柴油低温流动改进剂进行了感受性的实验研究.结果表明:不同的低温流动改进剂对同一种柴油感受性存在差别;存在差别的影响因素主要表现在低温流动改进剂的化学结构方面,如:分子结构、碳数分布、支链长度、极性基团、非极性基团;柴油中正构烷烃含量高使低温流动改进剂感受性变差.     

Solid-state polycondensation of natural aldopentoses and 6-deoxyaldohexoses. Facile preparation of highly branched polysaccharide

Solid-state polycondensation of natural aldopentoses and 6-deoxyaldohexoses was found to take place in the presence of H₃PO₄ (5 mol%) at 100-110 °C under a N₂ flow, giving highly branched polysaccharide (Conv. 47-81%, M_w=2700-12?000, M_n=1400-2900); the reaction mixtures were powdery throughout the polymerization. The product polysaccharide was per-O-methylated and subjected to the structure analyses. The acid-hydrolysis, which gave a variety of the partially O-methylated monosaccharides, suggested that the product polysaccharides proved to have highly branched structures consisting of both furanose and pyranose units. MALDI-TOF mass analysis revealed that the 1,4-anhydride terminal unit was formed and participated to the polymerization.     

Isolation,physicochemical properties,and in vitro antioxidant activity of polysaccharides extracted from different parts of Pinus koraiensis

The isolation and purification of polysaccharides extracted from the cones, bark, and needles of Pinus koraiensis (Korean pine) were studied. The amounts of polysaccharides were 42.7%, 53.4%, and 48.4% for cones, bark, and needles, respectively. All these samples contained uronic acid. The total protein and polyphenols were <4.5% for all three samples. With acid hydrolysis, seven polysaccharides were found in different molar ratios in each sample: D-ribose, L-rhamnose, L-arabinose, D-xylose, D-mannose, D-glucose, and D-galactose. The relationships between in vitro antioxidant properties (AOP) of polysaccharides extracted from different parts of the P. koraiensis tree are correlated with physicochemical properties (the amount of neutral sugars, uronic acid, and proteins). Moreover, the pinecone polysaccharides (PKCP) confirmed previously observed beneficial antioxidant capacity with an EC₅₀ of OH radical, ABTS radical scavenging, and reducing power of 6.54, 5.06, and 9.15 mg/mL, respectively. PKCP had the best antioxidant activity among the three samples.     

Synthesis,characterization, and evaluation of poly[n-alkyl(oxy)-n-hexyl acrylates]

Oxoalkyl acrylates of long-chain 7-oxo alcohols were synthesized as intermediate monomers for the preparation of poly[n-alkyl (oxy) -n-hexyl acrylates] for the first time. These polymers have wide applications as fluidity improvers (pour point depressants) for petroleum crude oils. Characterization of all the intermediate monomers was done by IR, ¹H-NMR, and MS, and that of polymers by IR, ¹H-NMR, and GPC. These polymers were systematically investigated for their efficacy as pour point depressants on three types of high waxy Bombay High (Indian) crudes. In addition to establishing the pour points, relevant rheological parameters of the untreated and the additive-treated crude oils were determined in the laboratory with a rotational viscometer. Results of the crude oils that were pre- and posttreated with these new polymers have shown enhanced activity of flow properties as compared to the crudes that were treated with poly(n-alkyl acrylate) flow improver.     

生物柴油低温流动改进剂复配研究

采用碱催化法制备菜籽油生物柴油和棕榈油生物柴油,对其主要品质指标进行分析;考察了添加不同的柴油低温流动改进剂及其复配物对生物柴油低温流动性能的影响。结果表明,柴油低温流动改进剂能够改善生物柴油低温流动性能;将其进行复配后,能表现出协同效应,取得更好的降滤效果,尤其能使饱和脂肪酸甲酯含量高的棕榈油生物柴油冷滤点降低8℃;不同生物柴油对柴油低温流动改进剂或其复配物感受性存在较大差异,不饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类较多、分布较广的菜籽油生物柴油对单一低温流动改进剂感受性好,而饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类分布较集中的棕榈油生物柴油对复配物感受性好。     

CFD simulation of hydrodynamics of gas–solid multiphase flow in downer reactors: revisited

In the present work, a k₁–ε₁–k₂–k₁₂ two-fluid model based on the kinetic theory of granular flow (KTGF) was employed to predict the flow behavior of gas and solids in downers, where the particles of small size as 70 μm in diameter apparently interact with the gas turbulence. The turbulence energy interaction between gas and solids was described by different k₁₂ transport equations, while the particle dissipation by the large-scale gas turbulent motion was taken into account through a drift velocity. Johnson–Jackson boundary condition was adopted to describe the influence of the wall on the hydrodynamics. The simulation results by current CFD model were compared with the experimental data and simulation results reported by Cheng et al. (1999. Chem. Eng. Sci. 54, 2019) and Zhang and Zhu (1999. Chem. Eng. Sci. 54, 5461). Good agreement was obtained based on the PDE-type k₁₂ transport equation. The results demonstrated that the proposed model could provide good physical understanding on the hydrodynamics of gas–solid multiphase flow in downers. Using the current model, the mechanism for formation and disappearance of the dense-ring flow structure and the scale-up characteristics of downers were discussed.     

低温流动性改进剂对低凝柴油性能的影响

通过考察几种低温流动性改进剂的活加量对常一线馏分、常二线馏分、常三线馏分、催化轻柴油等基础调合组分以及成品柴油冷滤点的影响,对以华北油田原油为原料生产低凝柴油的油品调合进行了研究。结果表明Ｄｏｄｉｆｌｏｗ４１３８和ＰＳＭ可做为华北石油管理局第一炼油厂生产柴油时的低温流动性改进剂,并确定了两种适宜的柴油生产方案。     

Acid hydrolysis of commercial chitosans

Commercial chitosans were subjected to controlled acid hydrolysis and their degrees of deacetylation (DD), molecular size and rheological flow profiles determined (pre‐ and post‐hydrolysis) by ¹H‐NMR spectroscopy, high‐performance size‐exclusion chromatography and rheometry, respectively. Hydrolysis resulted in DD increases between 4 and 11%. Unhydrolysed chitosans had M_w and M_n values in the ranges 700–1200 and 130–210 kDa, respectively. Chitosan with the smallest initial molecular size averages had the smallest averages after hydrolysis; however, a chitosan with an intermediate initial molecular size proved to be most resistant to hydrolysis. Molecular size trends were paralleled by zero shear viscosity (η₀) measurements determined by application of the Williamson model to rheological flow profile data. Viscosity is obviously related to molecular size, but does not necessarily reflect relative ease of hydrolysis, since specific hydrolysis conditions affect structurally similar polysaccharides in different ways (in terms of rate of depolymerisation and de‐N‐acetylation, etc), which are not simply due to differences in molecular size profiles pre‐hydrolysis. Copyright © 2005 Society of Chemical Industry     

Stabilization of pluronic gels in the presence of different polysaccharides

Several different polysaccharides have been added to pluronic F127 (poloxamer 407) gels to test their ability to stabilize the gels against dissolution in aqueous media over time. The studied polysaccharides include κ‐carrageenan, chitosan, hyaluronic acid, pectin, alginate, hydroxyethylcellulose, and ethyl(hydroxyethyl)cellulose. Although all the considered polysaccharides slowed down the dissolution time of the pluronic gels, unmodified polysaccharides only had a modest stabilization effect. However, hydrophobic modification of polysaccharides with a sufficiently long hydrocarbon chain (C₁₆) was found to partly prevent the gels from dissolving for more than 6 months. Shorter hydrocarbon chains did not have the same effect, even at high degrees of hydrophobicity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40465.     

Experimental and analytical study of countercurrent flow limitation in vertical gas/liquid flows

An experimental and analytical study of adiabatic countercurrent flow limitation (flooding) in single vertical ducts is reported. The experiments were carried out in a rectangular channel using saturated liquid and vapour of Refrigerant 12 (CCl₂F₂). The steady-state liquid delivery (flooding) curves as well as local pressure drop and void fraction distributions in the countercurrent flow were measured in a range of system pressures from p/p_crit = 0.16 to p/p_crit = 0.31, and for various total liquid injection rates and locations. The measured flooding curves j₁ = f(j_g) as well as pressure drop and void fraction during partial liquid delivery (j₁ < j₁ⁱⁿ) were not affected either by the axial liquid feed location or by the excess liquid rate carried upwards by the vapour. Moreover, for given flow conditions during flooding pressure drop and void fraction were essentially the same at different axial positions. Radial void fraction distributions evaluated from optical fibre probe data indicate an annular-type flow pattern. Based on this experimental evidence, a mechanistic core/film flow model was developed for the calculation of flooding. The analytical results are compared with the present high pressure and with comparable atmospheric pressure experimental data, showing reasonable overall predictions not only of the flooding curves, but also of the pressure drop in countercurrent flow.     

Synthesis and evaluation of acrylate polymers for improving flow properties of waxy crudes

N-Alkyl acrylates and n-alkyl methacrylates were prepared by esterification of acrylic and methacrylic acids with two long-chain alcohol blends NAFOL 2022 and NAFOL 1822. The prepared monomers were characterized and polymerized individually. In addition, copolymers of n-alkyl acrylate-n-alkyl methacrylate, and n-alkyl methacrylate–vinyl acetate and a terpolymer of n-alkyl acrylate–acrylic acid–vinyl acetate were also synthesized. These polymers were also characterized and then evaluated as flow improvers in Khalda mixtureand Salam Egyptian waxy crudes. The majority of the prepared additives showed good performance in improving the flow properties of the tested crudes. © 1994 John Wiley & Sons, Inc.     

Viscosity-index and polymer rheology. Comparison of concepts by means of experiments with some of the technically most important systems

Poly(n-decyl methacrylate), a statistical copolymer of ethylene and propylene, and a diblock copolymer of styrene and hydrogenated butadiene were studied as representatives of various kinds of viscosity-index (VI) improvers. Essomarcol 52 and AF 1 from Schindler served as base-oils, toluene and 1-phenyl dodecane were also studied. By means of viscosity measurements in the temperature interval from 37.8 to 98.9°C up to a concentration of typically 1 wt.-% polymer, the viscosity indices of the different systems and the corresponding intrinsic viscosities, Huggins coefficients, and activation energies of flow, E^≠, were determined. The discussion of the obtained experimental material demonstrates that the VI of a base-oil can be raised in two clearly distinguishable ways: (i) via an increase in the viscosity due to the mere presence of the polymer, without a change in E^≠ and (ii), less general, via an additional reduction of E^≠ as a consequence of thermodynamic interactions. Formulae are given from which these two contributions can be calculated.