TLC-FID Calibration and Accurate Weight Determination of SARA Fractions in Heavy Crude Oil

Abstract

The authors specifically aimed to separate and characterize clean saturates, aromatics, resins, and asphaltenes (SARA) fractions and develop standards for accurate quantification purposes. A standard method ASTM D4124-86 was employed for the SARA separation of an Athabasca crude oil. These four recovered fractions were analyzed by using an Iatroscan thin-layer chromatograph with flame ionization detection (TLC-FID). The Iatroscan response to the complete burnoff of known sample weights of each fraction deposited on chromarods via known volumes of standard solutions was determined and area count versus sample weight calibration graphs subsequently obtained. From the established weight versus peak area calibration curves for each pure separated SARA fraction their accurate quantitative percentage in an Athabasca heavy crude oil was determined.     

Total and partial erucate of pentaerythritol. Infrared spectroscopy study of relationship between structure, reactivity, and thermal properties

Esters of neopentylpolyols are an important starting base for synthetic lubricants. These bulky esters are generally prepared by an esterification reaction between a carboxylic acid and a neopentylpolyol. Because neopentylpolyols have a number of primary alcohol sites, a variety of partial esters is formed before total esters. In the present study, we investigated the reaction between pentaerythritol and erucic acid. The composition of the reaction mixture in erucic acid, partial esters, and total esters was monitored by thin-layer chromatography, coupled with flame-ionization detection. The pure esters and the esters in solution at different concentrations in xylene at different temperatures were analyzed by Fourier transform infrared spectroscopy. Erucic acid and partial esters in xylene coexist in the free form and as bound complexes. These findings furthered understanding of the reactivity and thermal properties of the partial esters.     

HYDROCARBON GROUP TYPES ANALYSIS OF PETROLEUM PRODUCTS: A COMPARATIVE EVALUATION OF HPLC AND TLC ANALYTICAL PERFORMANCE

ABSTRACT

Four petroleum samples representing a range of hydrocarbon composition were analyzed using the HPLC and TLC–FID techniques that provided separation and quantitation of saturates, aromatics, polars (resins) and asphaltenes. The results obtained from the two methods, for residues and crude oil samples, were not comparable because these samples contain high amount of polars and asphaltenes whereas VGO shows a very good comparison between the results obtained from the two techniques because of its asphaltenes-free and low polar composition. TLC–FID separation required a number of solvents while in HPLC, only one type of solvent was used. In TLC method, a number of samples can be analyzed simultaneously while in HPLC, only one sample is analyzed at a time. HPLC system analyzes a large number of sample in a complete automated fashion without operator involvement while the TLC method needs more involvement and attention of the operators. In HPLC, the aromatics can be further classified based on number of rings while in TLC–FID, aromatics were detected as one peak. The reproducibility of TLC–FID analysis for individual fractions was found good.     

Interference of polar lipids with the alkalimetric determination of free fatty acid in fish lipids

An examination of the suitability of an alkalimetric method for the determination of free fatty acid (FFA) contents in fats, oils, and lipid extracts was conducted by comparing AOCS method Ca 5a-40 with a method based on a Chromarod-latroscan thin-layer chromatography-flame-ionization detector (TLC-FID) system. The FFA contents determined by the alkalimetric method were consistently higher than the genuine FFA contents obtained by the latroscan TLC-FID method. Phospholipids were found to be the major components that contributed to the alkali-titratable, nongenuine FFA in the total FFA determined alkalimetrically. Contributions from other polar lipid components were smaller, but they dominated as the proportion of phospholipids fell. The other alkali-titratable polar components may include oxidized lipids and their by-products bound to protein fragments. The accurate determination of FFA contents by alkalimetric methods may only be applicable to those commercially refined fats and oils that contain negligible amounts of phospholipids. Corrections for the alkalimetrically determined FFA contents should be made for those fats and oils with relatively high phospholipid contents by correlating the nongenuine FFA contents and the phospholipid contents.     

棒状薄层色谱法(TLC-FID)预测储层稠油粘度

介绍了一种利用棒状薄层色谱—氢火焰离子化检测器联用技术(TLC-FID)预测储层中稠油粘度的方法,方便、快捷、经济。该方法包括3个步骤:首先,在工作区块内选取代表性稠油样品,用柱色谱制备出饱和烃、芳烃、非烃、沥青质组分,标定各组分在TLC-FID上的相对峰面积—质量校正系数;在此基础上,对一定数量稠油样品进行粘度测定和TLC-FID分析,建立工作区内稠油粘度与TLC-FID数据之间的指数数学关系;最后,测定待预测油层油砂抽提物的TLC-FID数据,通过所建立的数学关系计算其粘度。文中基于我国某油田特定区块的27个稠油样品,对该油田一口单井的152个油砂样品进行了应用研究,建立了该井的储层稠油粘度剖面,与实际情况基本吻合。      

Interfacial and Thermal Characterization of Asphaltenes Separated from Crude Oils Having Different Geological Origins

Abstract

Three crude oils having different geological origins, namely, DK from Eocene (Sylhet limestone and Langpar), SL from Barail (Oligocene), and JN from Tipam (lower Miocene), were selected. Asphaltenes were separated and characterized. Fourier transform infrared (FTIR) spectroscopy showed the presence of polar groups. Interfacial tension studies of the asphaltenes between benzene–water, toluene–water, and xylene–water showed the lowest interfacial tension with SL asphaltenes in a toluene–water system. Thermogravimetric analysis of asphaltenes indicates greater thermal degradation for DK asphaltenes. Asphaltenes were pyrolyzed and the pyrolyzed products were analyzed by gas chromatography/mass spectrometry (GC/MS). Based on the distribution pattern of n-alkanes in pyrolyzed product of asphaltenes, crude oils, and kerogens, it was concluded that crude oil and asphaltenes originate from the same source and asphaltenes are the unconverted parts of kerogens.     

油藏地球化学中TLC-FID族组分定量方法探讨及初步应用

采用两种标样方法对新站地区原油与氯仿沥青"A"样品族组分进行了薄层色谱-火焰离子检测(TLC-FID)定量分析,分析了两种标样方法的差异,并与经典的柱层析硅胶-氧化铝法(柱色谱)进行对比,结合研究区地质特征探讨了其初步应用.结果表明,标样2法与经典方法更为接近,标样1法存在一定偏差.另外,依据分析结果对新站地区葡萄花与...     

Three extraction methods for determination of lipids in fish meal: Evaluation of a hexane/isopropanol method as an alternative to chloroform-based methods

Three different extraction methods were compared for the determination of lipids in both oxidised and antioxidant-stabilised brown fish meal. The three methods under investigation were those of Smith-Ambrose-Knobl using chloroform/methanol/water, Bligh and Dyer also using chloroform/methanol/water but monophasic, and Hara and Radin using hexane/isopropanol. The fat content, determined gravimetrically, was significantly lower (P < 0.05) when hexane/isopropanol was used for lipid extraction from both oxidised and antioxidant-stabilised fish meal, than when either of the chloroform systems was used. Determination of lipid classes in the lipid extracts using silica gel thin-layer chromatography on Chromarods-SIII, with flame ionisation detection by latroscan, suggested that the lower lipid recovery by the hexane/isopropanol method may be due to a less effective extraction of the more polar lipid classes. including oxidation products, present in brown fish meal.     

Study of hydrogen generation from heavy oil gasification based on ramped temperature oxidation experiments

Hydrogen is a clean energy because of its high energy density and pollution-free combustion. The main ways of hydrogen generation are from coal and methane, as well as hydrogen generation from by-products of chemical plants. It had been reported that heavy oil reservoir in Margaret Lake in Canada produced up to 15 mol% hydrogen indicating that it is feasible to produce hydrogen by in-situ gasification (ISG) from heavy oil reservoir. However, there are relatively few studies on the mechanism and characteristics of hydrogen generation from ISG of heavy oil, the lower limit of hydrogen-production temperature, the interaction of produced gas and so on. Previous studies focused on the upgrading of heavy oil rather than hydrogen generation. In order to study the hydrogen generation mechanisms of different samples, The 4 types samples covering heavy oil, light oil, carbon samples were used and the saturate, aromatic, resin and asphaltene (SARA) components was measured by thin layer chromatography and flame ionization detection (TLC-FID). Then, the ramped temperature oxidation (RTO) experiments of 7 Runs of reservoir cores and sand-filling model were designed. The compositions and molar contents of produced gas were analyzed combined with gas chromatography (GC), and the lower limit temperature and the advantages of hydrogen generation from heavy oil were analyzed under different air/nitrogen injection rates based on a constant water injection rate. The results showed that the lower limit temperature of hydrogen generation from crude oil was about 500–550 °C and that of carbon was 700–750 °C. The reservoir core may had catalytic effect, which can promote hydrogen production. The highest hydrogen rate of RTO experiment with reservoir core can reach 55–60mol%, while that of sand-filling experiment was only 5–10mol%. The main chemical reactions for hydrogen generation from crude oil were coke gasification and water-gas shift. Therefore, the hydrogen production of heavy oil with high hydrocarbon ratio was significantly greater than that of thin oil. It showed the advantages of hydrogen generation from heavy oil. In addition, in order to quantitatively evaluate the efficiency of hydrogen production by gasification, the definition and calculation equation of hydrogen generation efficiency (HGE) were given. The HGE was defined as the ratio of hydrogen production volume and hydrogen consumption volume in a certain period of time (Δt). The E_hg can be used to quantitatively represent HGE, and the calculation of E_hg is the ratio of hydrogen production and twice of oxygen consumption in a period of time. The E_hg of Run1 and Run3 were calculated to be 1.47 and 0.15. It indicated that the hydrogen production efficiency of Run1 was about 10 times higher than that of Run3.