Jacky Kister

Comparison by Fourier transform infrared (FTIR) spectroscopy of different ageing techniques: application to road bitumens

FTIR spectroscopy was used to compare a direct and continued methodological approach of bitumen oxidation process (adapted IR cell), a road ageing, along with two ageing conventional tests: the Rolling Thin Film Oven Test (RTFOT) and the Pressure Ageing Vessel (PAV). This work gave clear indication that oxidation inside a cell can partly simulate the chemical evolution of road bitumens actually in service. Indeed, regarding the formation of carbonyl functions, an hour of cell oxidation is equivalent to two years of ageing on site. Furthermore the PAV ageing protocol could be simulated by 25 min of cell oxidation.

Changes in the chemical structure of low rank coal after low temperature oxidation or demineralization by acid treatment: Analysis by FT-i.r. and u.v. fluorescence☆

The studies have been conducted on low rank coal: Flambant de Provence, France, PRV=0.44 FTIR and UV synchronous fluorescence spectroscopy are used to study structural changes in low rank coal after natural oxidation or acid (HCl/HF) demineralization. The observed variations deal mainly with a decrease in aliphatic structures and an increase in the oxygenated species. A quantitative oxidation study of the effect of temperature, time, mineral matter and oxygen concentrations has been conducted by FTIR. An attempt to describe the oxygenated species by FTIR and to compare their evolution has been conducted. Various oxidation mechanisms are proposed according to the results.

Characterization of chemical structure, degree of maturation and oil potential of torbanites (type I kerogens) by quantitative FT-i.r. spectroscopy

Abstract The kerogen of Torbanites of various origins (natural and laboratory-heated samples) was examined by quantitative Fourier transform infrared spectroscopy (FT-i.r.). This study was carried out from difference spectra, obtained by low temperature ash (LTA) subtraction, or from deconvoluted regions of such spectra. The various indexes thus obtained allowed for determining the degree of natural and artificial evolution of Torbanites and the associated changes in chemical structure; comparing artificial versus natural evolution; and assessing the oil potential retained by matured Torbanite samples. The scopes and limitations of these FT-i.r. indexes were considered and compared with those of previously used methods. Quantitative FT-i.r. thus appears more efficient than elemental analysis or microspectrofluorimetry (in assessing the degree of natural evolution, in the first and last steps of maturation, respectively) and than solid-state 13 C nuclear magnetic resonance (n.m.r.) (in showing the relative enrichment in ether groups during evolution). When kerogen isolation via demineralization is performed, prior to i.r. examination, the drastic acid treatments then required may alter the chemical structure of organic matter; such a drawback is not encountered in studies based on LTA preparation and difference spectra.

Direct and continuous methodological approach to study the ageing of fossil organic material by infrared microspectrometry imaging: application to polymer modified bitumen

Abstract A new simulation method was developed for studying the ageing of polymer modified bitumens (PmBs). An ageing cell specially was designed and fitted to a Fourier transform infrared (FTIR) microscope to continually and directly study the oxidation of PmB by FTIR microscopy imaging. The method was applied to a styrene–butadiene–styrene (SBS) modified bitumen. This PmB features a two-phase structure with polymer-rich areas along with polymer poor regions. Changes in the chemical properties were observed during ageing. This structural and functional evolution was monitored in both phases simultaneously to determine the kinetics of appearance and disappearance of chemical species. The method also allows the study of ageing by kinetic mapping. Moreover, this methodology allows the analysis of PmB samples without destroying their internal equilibrium. This paper presents some of the possibilities of this new ageing cell.

Study of jojoba oil aging by FTIR

As the jojoba oil was used in cosmetic, pharmaceutical, dietetic food, animal feeding, lubrication, polishing and bio-diesel fields, it was important to study its aging at high temperature by oxidative process. In this work a FT-MIR methodology was developed for monitoring accelerate oxidative degradation of jojoba oils. Principal component analysis (PCA) was used to differentiate various samples according to their origin and obtaining process, and to differentiate oxidative conditions applied on oils. Two spectroscopic indices were calculated to report simply the oxidation phenomenon. Results were confirmed and deepened by multivariate curve resolution-alternative least square method (MCR-ALS). It allowed identifying chemical species produced or degraded during the thermal treatment according to a SIMPLISMA pretreatment.

FTIR and SUVF spectroscopy applied to reservoir compartmentalization: a comparative study with gas chromatography fingerprints results

Abstract The purpose of this study was to evaluate reservoir continuities and geochemical evolution of oils from individual reservoirs by using gas chromatography (GC) fingerprints method and to compare the results with those obtained from Fourier transform infra red (FTIR) and synchronous ultra violet fluorescence (SUVF) spectroscopy techniques. Six crude oils which belong to different levels of exploitation were selected from Alam El Bueib (AEB) oil field (Western Desert, Egypt). The samples studied belong to three different reservoir units in different wells. The results show that the all-independent techniques provide results in good agreement and that the oils characteristics and their evolution in the reservoir can be described similarly by fingerprints GC, FTIR and SUVF spectroscopy. The FTIR and SUVF spectroscopy techniques therefore constitute a rapid and non-expensive alternative for reservoir organic geochemistry studies.

Assessing petroleum oils biodegradation by chemometric analysis of spectroscopic data.

This study was conducted to classify petroleum oils in terms of their biodegradation stage by using spectroscopic analysis associated to chemometric treatments. Principal Component Analysis (PCA) has been applied on infrared and UV fluorescence spectra of Brazilian and Pyrenean oils. For Brazil samples, the method allowed to distinguish the biodegraded oils from the non-affected ones. Pyrenean sampling including oils at different levels of biodegradation has been chosen to follow their alteration rate. PCA loadings have shown spectral regions which have differentiated oils after biodegradation whereas Simple-to-use Interactive Self-Modelling Mixture Analysis (SIMPLISMA) has permitted to obtain a repartition in terms of components families (saturated, aromatic and polar ones) characterizing chemical composition of oils at different biodegradation degrees. Results are in good agreement with conclusions of usual hydrocarbon biomarker analysis.

GC-MS identification of biomarkers in road asphalts and in their parent crude oils. Relationships between crude oil maturity and asphalt reactivity towards weathering

Abstract Asphalt cements (vacuum residues of petroleum) used as binders for road construction can undergo weathering phenomena or natural oxidation to various degrees depending on their chemical structures and on their origin. The first aim of this study was to determine the characteristics of the source rocks generating the parent crude oils. The second aim was to correlate the chemical structures of recovered asphalt cements to the genesis data of their parent crude oils in order to predict their sensitivity towards weathering. Towards these ends, saturated fractions of sixteen asphalt cements and their parent crude oils have been analysed by GC-MS (SIR). Many linear, branched and naphthenic compounds from the saturated hydrocarbon fraction have been identified. Hopanes ( m z = 191 ), norhopanes ( m z = 177, 163 ) and steranes ( m z = 217 and 218 ) have been selected to characterize original and weathered asphalts as well as their parent crude oils. Using geochemical indices ( T s T s + T m , %C29 steranes, etc.), aliphatic structures of the asphalts and corresponding crude oils could be differentiated through principal component analysis (PCA). The selected variables involve geochemical indices and asphalt rheological characteristics. Results are in good agreement with the classification obtained from FTIR indices (linear alkanes, branched aliphatics, aliphatics versus aromatic structures, etc.). Moreover, good correlations in geochemical indices have been found between asphalts and their parent crude oils. Finally, it was also possible to predict some rheological properties (e.g., stiffness at low temperature) using a multilinear regression which involves geochemical indices of parent crude oils before any physical transformation (distillation, etc.) and FTIR indices of corresponding asphalt cements.

APPROCHE METHODOLOGIQUE DIRECTE ET CONTINUE DU PROCESSUS D'OXYDATION DES BITUMES PAR SPECTROSCOPIE INFRAROUGE A TRANSFORMEE DE FOURIER

Abstract (Direct continuous method for studying oxidation of bitumens by Fourier-transform infrared spectrometry). The method is based on the standard rolling thin-film oven test with oxidation in air at 163°C. A specially designed infrared cell is used. FTIR spectrometry provides spectral fingerprints which are characteristic for each bitumen.

Analysis and evolution of coals: UV fluorescence spectroscopy study (demineralized coals-oxidized coals)

Abstract A structural analysis of the organic part of 2 coals of different rank (Gardanne coal and Freyming coal) was performed by UV fluorescence spectroscopy (synchronous excitation-emission technique). The spectral study was made on different extracts (hexane, toluene, tetrahydrofuran and pyridine extracts) obtained by ultrasonic multiple step extraction. On a spectroscopic basis it is thus possible to clearly show the differences between coals of different rank and bring out the notion of “fingerprint” characteristic of a given coal. UV fluorescence spectroscopy also makes it possible to detect structural changes occurring in the aromatic part of coals after demineralization or oxidation.