Synthesis and evaluation of demulsifiers with polyethyleneimine as accepter for treating crude oil emulsions

Demulsifiers provide an important means of breaking water‐in‐crude oil, which are formed during crude oil exploitation. In present work, twenty polyether copolymers based on polyethyleneimine (PEI) were synthesized. The interfacial properties of the PEI polyethers at the water‐crude oil interface were described by interfacial tension (IFT) and interfacial dilational modulus. The effects of position isomerism, size of intermediate and ratio of ethylene oxide (EO)/propylene oxide (PO) on the demulsification efficiency of these polyethers were studied. The results show that different positions of the EO and PO in copolymers lead to huge difference in both interfacial properties and demulsification performance. Polymers with hydrophilic core and hydrophobic tails (Ex‐mn series) are not efficient on demulsification of water‐in‐oil emulsion whereas polymers with hydrophobic core and hydrophilic tails (Px‐mn series) are. Meanwhile, Px‐mn series show higher IFT and lower interfacial dilational modulus than Ex‐mn series. In the same series, the IFT and interfacial dilational modulus decrease with decreasing EO/PO ratio. In the series with best demulsification performance (P199‐mn series), 60 min water removal rates of the polymers increase with decreasing EO/PO ratio at 65°C. In other words, the longer the hydrophobic blocks of polymers, the stronger the demulsification capacity. The effect of concentration of demulsifier on the demulsification efficiency was also investigated. Copyright © 2015 John Wiley & Sons, Ltd.     

Electrospray ionization for determination of non‐polar polyaromatic hydrocarbons and polyaromatic heterocycles in heavy crude oil asphaltenes

Electrospray ionization (ESI) is the most common ionization method in atmospheric pressure ionization mass spectrometry because of its easy use and handling and because a diverse range of components can be effectively ionized from high to medium polarity. Usually, ESI is not employed for the analysis of non‐polar hydrocarbons, but under some circumstances, they are effectively ionized. Polyaromatic hydrocarbons and aromatic heterocycles can form radical ions and protonated molecules after ESI, which were detected by Fourier transform ion cyclotron resonance mass spectrometry. The highly condensed aromatic structures are obtained from a heavy crude oil, and the results show class distribution from pure hydrocarbons up to more non‐basic nitrogen‐containing species. By using different solvent compositions [toluene/methanol (50/50 v/v), dichloromethane/methanol (50/50 v/v), dichloromethane/acetonitrile (50/50 v/v) and chloroform], the results show that the lack of proton donor agent helps to preserve the radical formation that was created at the metal/solution interface inside the electrospray capillary. The results demonstrate that with an appropriate selection of solvent and capillary voltage, the ratio between the detected radical ion and protonated molecule form can be manipulated. Therefore, ESI can be expanded for the investigation of asphaltene and other polyaromatic systems beyond the polar constituents as non‐polar hydrocarbons can be efficiently analyzed. Copyright © 2015 John Wiley & Sons, Ltd.     

A kinetic study on the reaction between glycidyl vinyl ether and carbon dioxide with quaternary ammonium salts as catalyst

The kinetics of the reaction between glycidyl vinyl ether (GVE) and carbon dioxide has been studied by using quaternary ammonium salts as catalyst. The catalysts having larger cations and more nucleophilic counter-anions showed higher activity. In a semi-batch reactor where CO₂ is continuously supplied, the reaction is first order with respect to the concentration of GVE. In a high pressure batch reactor, the reaction is first order with respect to both GVE and CO₂ and second order overall. In the latter case, a simple method to evaluate the rate constant and Henry's constant is also proposed.     

Syntheses of fluorous quaternary ammonium salts and their application as phase transfer catalysts for halide substitution reactions in extremely nonpolar fluorous solvents

Perfluoromethyldecalin solutions of the fluorous alkyl halides R_f8(CH₂)_mX (m=2, 3; X=Cl, I) are inert toward aqueous NaCl, KI, KCN, and NaOAc. However, substitution occurs at 100 °C in the presence of 10 mol % of the fluorous ammonium salts (R_f8(CH₂)₂)(R_f8(CH₂)₅)₃N⁺ I⁻ (1) or (R_f8(CH₂)₃)₄N⁺ Br⁻ (2) (10 mol %), which are fully or partially soluble in perfluoromethyldecalin under these conditions. Stoichiometric reactions of (a) 1 and R_f8(CH₂)₃Br, and (b) 2 and R_f8(CH₂)₂I are conducted in perfluoromethyldecalin at 100 °C, and yield the same R_f8(CH₂)_mI/R_f8(CH₂)_mBr equilibrium ratio (60-65:40-35). This shows that ionic displacements can take place in extremely nonpolar fluorous phases, and suggests a classical phase transfer mechanism for the catalyzed reactions. Interestingly, the non-fluorous ammonium salt mixture CH₃(CH₃(CH₂)_m)₃N⁺ Cl⁻ (3, Aliquat^® 336; m=2:1 7/9) also catalyzes halide substitutions, but under triphasic conditions with 3 suspended between the lower fluorous and upper aqueous layers. NMR experiments establish very low solubilities in both phases, suggesting interfacial catalysis.     

高胶质沥青质超稠油降粘剂YZ-31的研究

针对高胶质和沥青质含量超稠油的特点,室内研究了一种高效油溶性稠油降粘剂YZ-31,对不同降粘剂对超稠油降粘效果进行了比较。探讨了超稠油降粘剂YZ-31加量、温度等因素对降粘效果的影响。结果表明:油溶性降粘剂YZ-31对高胶质和沥青质含量的胜利油田郑家超稠油降粘效果明显。在50oC,5 wt%的降粘剂加量下对三种实验超稠油样品的降粘率都在95%以上。     

Preparation of molecular imprinted polymer with quaternary ammonium groups as recognition sites for separation of pig cyclophilin 18 and bovine serum albumin

We introduce a new type of molecular imprinted polymer (MIP) with immobilized assistant recognition polymer chains (ARPCs) to create effective recognition sites. In this work, cloned pig cyclophilin 18 (pCyP18) and BSA were used as templates, respectively. The template protein was selectively assembled with ARPCs from the library which consists of numerous limited length polymer chains with randomly distributed recognition sites of the quaternary ammonium cationic groups and immobilizing sites. The assemblies of protein and ARPCs were adsorbed by macroporous microspheres and immobilized by cross‐linking polymerization. After removing the templates, the two kinds of synthesized MIPs were used to adsorb cloned pCyP18 and BSA from protein mixtures respectively and both showed high selectivity. It confirms that this new method is suitable to separate proteins of both low and high molecular weight. The extended experiment on adsorption of natural pCyP18 from cytosol shows that the obtained MIP using cloned protein as template can be used to enrich natural protein of low content.     

Towards a combined use of Mn(Salen) and quaternary ammonium salts as catalysts for the direct conversion of styrene to styrene carbonate in the presence of dioxygen and carbon dioxide

The use of oxygen in combination with carbon dioxide to afford the direct conversion of alkenes into cyclic carbonates could help to promote the greenhouse gas while minimizing the impact of the oxidation reaction on the environment. In this work, we focused, for the first time, on the association of two catalytic systems individually efficient for the epoxidation of styrene (Mn(salen)/O₂ bubbling/isobutyraldehyde at 80 °C) and the cyclocarbonatation of styrene oxide (choline chloride/CO₂ at 15 bar and 120 °C). First, the feasibility of the cyclocarbonatation reaction, starting from the non-isolated epoxide, has been proven as styrene carbonate was formed with a 24% yield. The objective was, then, to determine the best conditions allowing the overall transformation in a common solvent. Taking into account the differences in optimal temperatures and kinetics of the two individual steps, it was decided to vary the temperature during the reaction [first 80 °C (3 h) and 120 °C (23 h)]. Under these conditions, styrene was converted into the epoxide but, unfortunately, styrene carbonate formation could not be demonstrated. Blank experiments have clearly shown that isobutyraldehyde, which is essential to the first step, must be completely consumed before the temperature rise. Otherwise, autoxidation of the aldehyde in the presence of styrene oxide at 120 °C leads to other products than styrene carbonate.     

Direct chlorine determination in crude oils by energy dispersive X-ray fluorescence spectrometry: An improved method based on a proper strategy for sample homogenization and calibration with inorganic standards

Official guidelines to perform chlorine determination in crude oil are (i) American Society for Testing and Materials (ASTM) D6470, which is based on the extraction of water from the oil and subsequent determination of the chloride by potentiometry, (ii) ASTM D3230, that measures the conductivity of a solution of crude oil in a mixture of organic solvents and (iii) US Environmental Protection Agency (EPA) 9075 that uses energy dispersive X-ray fluorescence spectrometry to quantify chlorine and it is applicable for the range from 200 μg g^− 1 to percent levels of the analyte. The goal of this work is to propose method to quantify lower amounts of chlorine in crude oil using energy dispersive X-ray fluorescence spectrometry using a simple calibration strategy. Sample homogenization procedure was carefully studied in order to enable accurate results. The calibration curve was made with standards prepared by diluting aqueous NaCl standard in glycerin. The method presented a linear response that covers the range from 8 to at least 100 μg g^− 1 of chlorine. Chlorine in crude oil samples from Campos Basin - Brazil were quantified by the proposed method and by potentiometry after extraction of chlorine from the oil. Results achieved using both methods were statistically the same at 95% confidence level.     

Evaluation of some functionalized imidazoles and 1,2,4-triazoles as antioxidant additives for industrial lubricating oils and correlating the results with the structures of additives using empirical AM1 calculations

Functionalized 4,5-diphenyl-imidazoles, 4,5-diphenyl-1,2,4-triazoles and 5-(o-hydroxyphenyl)-4-phenyl-1,2,4-triazoles at the 2-position with thiol, thiomethyl and thiobenzyl groups, have been tested as antioxidant additives for lubricating oils. Whereas the thiomethyl groups in such compounds increased the antioxidant property than the thiol group, the corresponding thiobenzyl groups did the reverse. The results can be explained, based on correlating the electron donating and withdrawing abilities of the substituents with the oxidation stability. The triazoles carrying a phenolic hydroxyl group have more antioxidant power than those without such a group. The imidazoles gave the oils more oxidation stabilities than the two types of triazoles with the same functionalities. The 4,5-diphenyl-2-thiomethyl-imidazole (2), as an additive, has the highest antioxidant property, reaching the level of standard one when its concentration is 1.0% wt. instead of the 0.8% wt. of the standard. The correlation of the antioxidant character of the heterocyclic additives with their structures has been investigated using the semiempirical gas phase AM1 calculations for the studied heterocycles. The relative stability of the imidazoles 1 and 3 compared to 2 were in the order 2 > 1 > 3. Similarly, the relative stability of the triazoles are in the same order where 5 > 4 > 6 and 8 > 7 > 9.     

Bis[4-monosubstituted-5(4H)oxazolinones] as coupling agents for block copolymer synthesis: Reaction with amine-terminated oligomers and with hydroxy-terminated/amine-terminated oligomer mixtures

Block copolymers were prepared by the bulk reaction of mixtures of amine-terminated aliphatic polyamides and polyethers with bis[4-monosubstituted 5(4H)-oxazolinones] as the coupling agents. The simultaneous chain-coupling reaction of amine-terminated polyethers and hydroxy-terminated polyesters with these coupling agents also was investigated. As indicated by NMR and size exclusion chromatography studies, block copolymers of M_n ≥ 10,000 were obtained without side reactions in a much shorter reaction time than required when the conventional reaction was used between oligomers bearing mutually reactive end-groups. The block copolymers behaved as thermoplastic elastomers. Their thermal and thermomechanical properties were evaluated by differential scanning calorimetry and dynamic mechanical thermal analysis and compared to the block copolymers synthesized in the conventional way. When low molar mass oligomers were used (M_n ≤ 1000), copolymers of low crystallinity or amorphous copolymers were obtained. This was assigned to the disruption of chain regularity induced by the presence of the chain-coupling-agent moieties. However, properties comparable to those of copolymers obtained by using the conventional method were obtained by reacting oligomers of M_n ≥ 2000. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4412–4421, 1999