Analysis of Syneresis of HPAm/Cr(II) and HPAm/Cr(III) Acetate Gels Through 1H Nuclear Magnetic Resonance,Bottle Testing,and UV-vis Spectroscopy

Abstract

Polymer solutions with 7500 mg/L of partly hydrolyzed polyacrylamide were crosslinked with Cr(III) acetate 50% active, Cr(III) acetate hydroxide, and Cr(II) acetate respectively. A syneresis-inducing polymer to crosslinker weight ratio of 5/1 was employed. An empirical correlation was found between ¹H NMR data and gel syneresis. Chromium speciation indicated that at the experimental conditions used aging the gels did not favor the oxidation of Cr(II) or Cr(III) to Cr(VI). The polymer solution crosslinked with Cr(III) acetate 50% active behaved similar to that cross-linked with Cr(III) acetate hydroxide.     

The Structural Characterization of Saturate,Aromatic, Resin,and Asphaltene Fractions of Batiraman Crude Oil

Abstract

The structural characterization of fractions of Batiraman crude oil, which is the heavy crude oil from a field in the southeastern part of Turkey, was investigated. Batiraman crude oil and its saturate, aromatic, resin, and asphaltene (SARA) fractions were seperated. Treatment of crude oil with n-heptane provided the separation of asphaltene. Maltene was collected by evaporating the n-heptane from the filtrate. Then, maltene was separeted into saturates, aromatics, and resins by SARA technique. Maltene was separated into saturate, aromatic, and resin fractions using column chromatography. SARA fractions were quantified on a weight percent basis. Fractions of Batiraman crude oil were characterized by elemental analysis, proton nuclear magnetic resonance (¹H NMR) analysis, electrospray ionization mass spectrometry (ESI-MS), and Fourier transform infrared (FTIR) spectroscopy techniques.     

Study of the coordinative nature of alkylaluminum modified Phillips CrOx/SiO2 catalyst by multinuclear solid-state NMR

Solid-state nuclear magnetic resonance spectroscopy was used to investigate the coordinative states of surface Al species on various alkylaluminum-modified Phillips CrOx/SiO2 catalysts.The alkylaluminum-modified Phillips CrOx/SiO2 catalysts were examined via ethylene homopolymerization.1H and 27Al magic angle spinning（MAS） nuclear magnetic resonance（NMR） spectra clearly demonstrated that the existing states of surface Al species in alkylaluminum-modified catalysts strongly depended on the type of alkylaluminum cocatalyst,concentration of alkylaluminum and the calcination temperature.1H MAS NMR spectra of alkylaluminum-modified Phillips CrOx/SiO2 catalysts,calcined at two different temperatures,exhibited similar trends in peak shift.1H spectra showed that with an increase of Al/Cr ratio and calcination temperature,the main peak shifted to high field,indicating that the dominant surface proton species changed from hydroxyl to ethoxyl and ethyl groups.27Al MAS NMR spectra showed the presence of three different coordination states（6-,5-,and 4-coordinated Al species） in the alkylaluminummodified Phillips catalysts.In comparison of different alkylaluminum cocatalysts,it was found that the reactivity of alkylaluminum modified Phillips catalyst decreased in the order of TEA〉DEAH〉DEAE.The amount of 4-coordinated Al species of Phillips catalysts modified by TEA,DEAE and DEAH also decreased in the order of TEA〉DEAH〉DEAE,indicating that the presence of 4-coordinated Al species is related to the polymerization activity.     

Synthesis,interface activity and oil flooding experiment with an authentic sandstone microscopic model of cationic gemini surfactant

In this work, a series of cationic gemini surfactants with different hydrophobic tails were prepared and characterized by element analysis, IR spectra, and ¹H NMR spectra. The influencing factors of physic-chemical properties of these surfactants were carefully studied. The critical micelle concentration (CMC) of all the surfactants ranged from 3.87 × 10^?4 mol L^?1 to 8.97 × 10^?4 mol L^?1 and the values (γ_cmc) also ranged from 28.62 mN m^?1 to 34.07 mN m^?1 at CMC level by surface tension experiments. The consequences of the oil/water interface tension experiments indicated that all these prepared surfactants could lower oil/water interface tension to ultra-low with the combination of Na₂CO₃. C₁₂-2-C₁₂, and C₁₄-2-C₁₄ were chosen as the representative to evaluate the displacement efficiency in the oil flooding experiments using authentic sandstone microscopic model. The results showed that these surfactants could effectively improve the displacement efficiency by 10–20%.     

Changes in Asphaltenes Properties Modified with Fe in Hydrotreating Reactions

Abstract

The properties of the Hamaca of asphaltenes extra-heavy crude oil (AsfH) of Petroliferous Orinoco Belt can be modified for evaluating the changes produced with hydrotreating (HDT). One characterized the solid modified by means of UV-visible spectroscopy and nuclear magnetic proton resonance (NMR ¹H). The samples were put under hydrotreating to 200°C to avoid thermal cracking, atmospheric pressure, and a flow of feeding of 10.5 mL/hr in a fixed-bed reactor in the presence of H₂S generated in situ. The reactivity was followed by gas chromatography (GC). All the samples were evaluated before and after being hydrotreated by ¹H NMR, total sulfur analysis, and determination of molecular weight average by vapor pressure osmometry (VPO). The obtained results suggest the iron possibly is inserted in the structure of the asphaltene forming a new active phase catalytically, presumably a mixed sulfide (pyrrotite type) of iron-metal of transition (V and Ni) present in the asphaltene.     

Modification and characterization of NaY molecular sieve by Cr3+ and its adsorptive denitrogenation from model fuel

Abstract

The CrY, which was modified by Cr³+ from NaY, was confirmed by characterization with FT-IR, XRD, N₂ adsorption-desorption, and it was used to adsorb quinoline from model fuel. The suitable modification conditions were modified twice by 0.5?mol/L cobalt nitrate solution at 40?°C. The FT-IR spectra indicated the disappearance of 1147?cm^?1 peak and the blue shift of 1024?cm^?1, implying that Cr³+ had exchanged Na⁺ and successfully incorporated into the framework of NaY. The static denitrogenation experimental results indicated that the adsorption between quinoline and CrY was the coordination adsorption and π complex adsorption. The suitable conditions were 30?min at room temperature and the adsorption temperature had minor effect on denitrogenation. The kinetic model of CrY adsorbing quinoline belonged to Langmuir and Freundlich adsorption model.     

Synthesis and Surface Active Properties of Novel Nonionic Aryl Oleic Diethanolamide Surfactants

Abstract

A series of novel aryl oleic diethanolamide (AOD) surfactants with different hydrophobic groups were synthesized. An aromatic ring introduced to a long alkyl chain had a significant effect on reducing water surface tension. The critical micelle concentration (CMC) and the surface tension (γ _cmc ) at the CMC were investigated. The CMC was 4.56 × 10^?8 mol/L to 5.83 × 10^?6 mol/L for AOD1:1 (molar ratio of aryl oleic acid: diethanolamide = 1:1) and corresponding γ _cmc was 36.4 mN/m to 39.3 mN/m. The CMC of AOD1:2 (molar ratio of aryl oleic acid: diethanolamide = 1:2) were in 1.21 × 10^?7–9.98 × 10^?6 mol/L and γ _cmc were in 31.6–34.4 mN/m.     

NaAlO2溶液中铝酸根离子的微观结构

 应用IR、²⁷Al NMR 和UV3种波谱方法对不同方式配制的Al₂O₃浓度和苛性系数基本相同的四种NaAlO₂溶液进行了详细的表征。结果表明IR、²⁷Al NMR和UV3种光谱方法给出的信息可以相互补充支持,共同给出NaAlO₂溶液中铝酸根离子的微观结构。溶液配制方式对NaAlO₂溶液中铝酸根离子的微观结构具有显著影响,4种NaAlO₂溶液中铝酸根均以四配位[Al(OH)₄]^-为主体离子,可以排除六配位[Al(OH)₆]^3-的存在; 二聚[Al₂O(OH)₆]^2-含量因配制方式不同存在显著差别,在方式Ⅰ配制的溶液中二聚[Al₂O(OH)₆]^2-含量很少或不存在,在方式Ⅱ、Ⅲ、Ⅳ配制的溶液中显著存在二聚[Al₂O(OH)₆]^2-,在溶液Ⅱ、Ⅲ中还存在尚未确定结构的离子。     

n-DIOCTADECYL FUMARATE–VINYL ACETATE COPOLYMER: SYNTHESIS,CHARACTERIZATION AND APPLICATION AS FLOW IMPROVER FOR OILS

ABSTRACT

Monomer n-dioctadecyl fumarate (DOF), and copolymers (C₁₈FVA) of DOF with vinyl acetate were synthesized. Monomer and copolymers were characterized by IR, ¹H-NMR, VPO and DSC. Due to the special structure of DOF, only copolymers containing 45.9%–97.8% (mol) DOF were obtained. The crystalline CH₂ numbers on polymer side chain χ were calculated from enthalpy determined by DSC, and it was found that χ slightly decreased with increasing vinyl acetate content. C₁₈FVA can be used as flow improver for viscous oil and residual oil, and the more the crystalline CH₂ number on the side chains, the better lattice match between copolymer and wax crystal structure of oils.     

Structural Aspects of Crude Oil Derived Asphaltenes by NMR and XRD and Spectroscopic Techniques

Abstract

Asphaltene samples obtained from crude processed at two Indian refineries were characterized for chemical composition and structure by nuclear magnetic resonance (NMR), X-ray diffractometry (XRD), fluorescence spectroscopic techniques, and chromatographic (column and GPC) techniques. Estimation of NMR average structural parameters were obtained by combined ¹H, NMR ¹³C, NMR DEPT-45, and QUAT pulse sequence spectral editing techniques. The macrostructure and crystalline parameters of these samples were obtained by XRD. The nature of the functional groups have been obtained by IR technique. A combined NMR and XRD parameters were used to estimate the size of average aromatic structural units. Asphaltenes from one of the crudes (ASP-A) was found to be highly pericondensed, highly substituted, and higher molecular size compared to ASP-B asphaltene molecules. The number of aromatic sheets per unit sheets are 3.7 and 2.5 in the sample ASP-A and ASP-B, respectively. Both the asphaltene molecules in the samples have periodically and systematic arrangement of aromatic sheets in the unit sheet. The number of aromatic rings per unit sheet in ASP-A and ASP-B are 6.0 and 5.0, respectively. The fluorescence spectral studies has also exhibited λ _max (the wavelength of maximum intensity) at 505 and 509 nm confirming to pericondensed higher polycondensed aromatic ring system in both the samples. The analysis of liquid chromatographic fractions of these samples show that each sample is composed of several polycondensed aromatic systems where unit sheet of ring sizes vary from 1.8 to 6.3 with varying molecular sizes. These structural parameters allowed a model structure of the asphaltenes to be constructed.     

STUDY ON THE STRUCTURE OF HEAVY OILS

ABSTRACT

The structural parameters of six heavy oils have been calculated with n-d-M, Brown-Ladner and ¹HNMR/IR method in this paper. The aliphatic H/C atomic ratio Hs/Cs i.e. x values were obtained from IR spectra combining with ¹HNMR spectra. The comparison of structural parameters calculated by ¹HNMR/IR, Brown Ladner and n-d-M methods were carried out for the six heavy oils. It is proposed that the ¹HNMR/IR method gives more precise average molecular parameters than the Brown-ladner method. N-d-M method can gives right molecular structural parameters for some heavy oils with lower molecular weight, but the information of molecular structure obtained by it is limited.     

Effect of Severity on Hydrotreating of Demetallized Oil Monitored by 1H-NMR Spectroscopy

Abstract

A study on aromatic hydrogenation of demetallized oil has been carried out using a commercial catalyst under pilot plant reaction conditions similar to those found in industrial processes. The feedstock was contacted with the catalysts in a trickled bed reactor unit at 330°C, 350°C, and 370°C. A combination of physicochemical characterization of feed and products and ¹H-NMR spectra was used to monitor changes in the aromatic fractions caused by variation in reaction temperature. Analysis of the ¹H-NMR spectra, along with the quantitative variation in the areas of the resonance lines, showed that the diaromatics with relatively long alkyl changes present in the lightest distillation cuts of the products were highly hydrogenated. In contrast, smaller changes in aromaticity in the heaviest fractions were observed under the same conditions. A limit of about 2 wt% of the integrals corresponding to the diaromatic+ species suggests a thermodynamical limitation of hydrogenation under the studied reaction conditions.     

CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES IN FORTIES AND KUWAIT PETROLEUM CRUDES

ABSTRACT

Alkane hydrocarbon fractions from Forties (North Sea) and Kuwait petroleum crudes, separated by distillation, solvent extraction and silica-gel column chromatography and sub-fractionated by molecular-sieve adsorption, have been examined by gas chromatography (GC) ¹H and ¹³C ( NMR spectroscopy, GC-mass spectrometry (MS) and field desorption (FD)MS. GC indicates that Forties contains rather more acyclic isoprenoids and cyclic alkanes than Kuwait; FDMS of Kuwait shows molecular-weight ranges for mono-, di-, tri-, tetra- and pentacyclic alkanes. ¹³C NMR spectra provide evidence of higher aromatic carbon, C_A, in Forties than Kuwait and longer T₁ relaxation times.     

Kinetics Study of CO2 Absorption into Solutions of UDS

Abstract

CO₂ absorption kinetics in united-developed desulfur solvent (UDS; a multicomponent solvent) and methyldiethanolamine solutions are measured in a disk column under the temperature range from 303 to 323 K and solution concentrations range from 0.35 to 4.371 mol·L ^?1. Under the condition of UDS concentration of 50% (4.371 mol·L ^?1) and temperature of 313 K, N and k_obs are 5.561 × 10^?6 kmol·m ^?2·sec ^?1 and 4,183.372 sec^?1 , respectively. The absorption activation energy of CO₂ into UDS is 44.92 kJ·mol ^?1.     

A novel La3+–Zn2+–Al3+–MoO42− layered double hydroxides photocatalyst for the decomposition of dibenzothiophene in diesel oil

A new type of photocatalyst, La³⁺-Zn²⁺-Al³⁺-MoO₄^2? layered double hydroxide (LDH) (La:Zn:Al = 1:7:2), was prepared by a complexing agent-assisted homogeneous precipitation technique. The LDHs were used as catalysts for the desulfurization of diesel oil under UV irradiation. As revealed by the results, the catalyst showed superior desulfurization efficiency and recycling performance. Under UV irradiation, the desulfurization efficiency was 84% in 60 min. In La³⁺–Zn²⁺–Al³⁺–MoO₄^2? LDHs, the introduction of MoO₄^2? increased the interlayer space for promoting the adsorption of dibenzothiophene, and MoO₄^2? might act as the active sites for the oxidation of dibenzothiophene, resulting in the high desulfurization efficiency.     

A novel carbonate as a diesel fuel additive

A new oxygenate 2, 2^/-diethoxyethyl carbonate was synthesized through transesterification using dimethyl carbonate and ethylene glycol monoethyl ether as raw materials and its chemical structure was identified through FT-IR, ¹H NMR, and GC-MS analyses. The oxygenate is miscible with individual hydrocarbons at normal temperature. When 2, 2^/-diethoxyethyl carbonate is added to diesel fuel, kinematic viscosity decreases slightly, smoke point increases linearly, flash point and solidifying point decline remarkably even at low content level of 5%(v), whereas they do not decrease further with the increase in its content level. When a diesel engine was fueled with a diesel fuel containing 25%(v) of the oxygenate, the smoke emissions were reduced up to 83.3%, the energy consumption was decreased by up to 15.5%, whereas the power output dropped noticeably at high speed.     

The Behavior of Polymers as Viscosity Index Improvers

Abstract

In the present work, six copolymers were prepared by reaction of 2-ethylhexyl methacrylate with vinyl acetate monomer by different molar ratio to produce copolymers (ν₁, ν₂, ν₃, ν₄, ν₅, and ν₆). The composition of these copolymers were determined by molecular weight (using Gel Permeation Chromatography (GPC) Water 600 E.) and by ¹HNMR (by 300 MHz Spectrometer w-P-300, Bruker) which indicate that the copolymers are alternating copolymers with reactivity ratio of 2-ethyl hexyl methacrylate is 0.65 and vinyl acetate is 0.51. The efficiency of the prepared copolymers as viscosity index improvers for lube oil was studies. From the data obtained, it was found that the efficiency as viscosity index improvers increases by increasing the molecular weight of the prepared polymers and increasing the concentration of these copolymers. The data were discussed on light of the chemical structure and reactivity ratio of the prepared copolymers.     

Synthesis,characterization, and thermal analysis of a new energetic salt based on 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate

4-Amino-1,2,4-triazolium 1?-hydroxy-1H,1?H-5,5?-bitetrazol-1-olate (ATHBTO) was synthesized by reacting 4-amino-1,2,4-triazole (AT) and 1H,1′H-5,5′-bistetrazole-1,1′-diolate dihydrate (H₂BTO·2H₂O). Its crystal structure was characterized through single-crystal X-ray diffraction. Meanwhile, FTIR, ¹H NMR, ¹³C NMR, and elemental analysis were also introduced to analyze its composition. The thermal stability was investigated by differential scanning calorimetry, thermogravimetric analysis, and thermogravimetric tandem infrared spectrum. Results indicated that ATHBTO exhibited excellent resistance to thermal decompositions reaching 511.4 K and had a 64.6% mass loss between 475.7 and 552.3 K. The kinetics parameters were calculated by Kissinger’s method and Ozawa–Doyle’s method. Moreover, according to the Kamlet–Jacobs formula, the calculated detonation velocity and detonation pressure of ATHBTO attained 8218 m/s and 28.69 GPa, respectively.     

A New Synthetic Route for 3,3′-Bis(fluorodinitromethyl)difurazanyl Ether (FOF-13) and Its Energetic Properties

A new protocol for preparation of 3,3-bis(fluorodinitromethyl)difurazanyl ether (FOF-13) was developed. It involves (i) nitration of 3,3’-bis(chlorohydroxyminomethyl)difurazanyl ether with N₂O₅/MeCN to give 3,3-bis(chlorodinitromethyl)difurazanyl ether (4), (ii) reduction of 4 with KI/MeOH to obtain potassium salt of 3,3’-bis(dinitromethyl)difurazanyl ether (6) and (iii) fluorination of 6 with XeF₂ in anhydrous acetonitrile to form the desired FOF-13. FOF-13 was fully characterized by IR, ¹³C NMR, ¹⁹F NMR, and elemental analysis. FOF-13 exhibits excellent physicochemical and detonation properties, such as high density (1.91 g cm^?3), good thermal stability, reasonable impact sensitivity (14 J) and friction sensitivity (64%), high measured detonation velocity (8497 m s^?1 at 1.69 g cm^?3). Furthermore, the precursors 4 and 6 were developed for the first time.     

Synthesis and optimization of a new MIL-100 adsorbent for removing basic N-compounds from liquid fuels

Abstract

In this work, the effects of synthesis conditions of MIL-100(Cr) as an adsorbent for quinoline (QUI) were evaluated by performing Taguchi-designed experimental tests. According to the analysis of variance (ANOVA), synthesis temperature was the most influential factor in maximizing QUI adsorption capacity of MIL-100(Cr). Moreover, the optimum temperature, time and reactants molar ratio were found to be 393?K, 15?h and 0.67, respectively. The QUI adsorption capacity of optimized MIL-100(Cr) was 15.70?mg_N.g^?1_ads. This adsorbent was characterized by specific surface area (BET), X-ray powder diffraction patterns (XRD) and Fourier transform infrared spectroscopy (FTIR) tests.