Characterization of Indian origin oil shale using advanced analytical
techniques
Ravindra Kumar ⇑,Veena Bansal,R.M.Badhe,Indu Sekhara Sastry Madhira,Vatsala Sugumaran,Saeed Ahmed,Jayaraj Christopher,Mitra Bhanu Patel,Biswajit Basu
Indian Oil Corporation Limited,Rearch &Development Centre,Sector-13,Faridabad 121007,Haryan
a,India
h i g h l i g h t s
The paper highlights the detailed characterization of Indian origin oil shale. There is no work reported on detail characterization of Indian origin shale oil. The ICAP and XRD identify the metals and minerals in oil shale.
The IR,NMR and MS give the information regarding hydrocarbons and structural parameters. Indian origin shale oil is carbon rich in nature and contains a significant component of aromatics.
a r t i c l e i n f o Article history:
Received 5January 2013
Received in revid form 4May 2013Accepted 17May 2013
Available online 4June 2013Keywords:Oil shale
Metal analysis
Hydrocarbon analysis Analytical techniques
a b s t r a c t
The paper highlights the detailed characterization of Indian origin oil shale using various analytical tech-niques viz.,Elemental analysis,Induced Coupled Argon Plasma (ICAP),X-ray Diffraction (XRD),Gas Chro-matography (GC),Infrared spectroscopy (IR),Nuclear Magnetic Resonance (NMR)spectroscopy and High Resolution Mass Spectrometry (HRMS).The study also focud on the molecular characterization of two shale oil samples obtained by retorting method from oil shales.A method bad on NMR spectroscopy has been developed for the estimation of total aromatics,types of aromatic substituent’s and average alkyl chain length of saturates in shale oil samples.Detailed hydrocarbon type analysis in terms of 22class has been carried out by HRMS.The results of aromatics obtained by the 1H NMR method,corre-lated with HRMS data.The detailed analys of Indian origin oil shale provide in depth structural infor-mation regarding the metals,minerals and hydrocarbons.
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1.Introduction
Oil shale is a natural,impermeable,fine-grained,laminated black or brown combustible material,and it consists of complex organic material of high molecular weight called kerogen which is finely distributed in an inorganic matrix [1].As a kind of fossil fuel similar to coal,oil shale has a higher mineral content.It is be-lieved that the minerals in oil shale will affect the reaction of or-ganic matter physically and chemically [2,3].In the western United States,large oil shale deposits exist in Colorado,Utah,and Wyoming [4]and have been considered for utilization during peri-ods of high crude oil prices.Patterson [5]did substantial rearch on Australian oil shale from different deposits.Their main focus was on the mineralogy of Australian oil shale and its effect on oil shale retorting.Jabber et al.[6]described about Jordan oil shale from different deposits and compared with Colorado oil shale.According to Jabber et al.Jordan organic matter (shale oil)contains 8.5–10.3%of sulfur.Oil shales have been divided into three catego-ries bad on mineral composition –carbonate-rich shale,siliceous shale and cannel shale.Carbonate-rich shales derive their name from the large amount of carbonate minerals such as calcite and dolomite.Siliceous oil shales are usually dark brown or black shales.Siliceous oil shales are not rich in carbonates but rather in siliceous minerals such as quartz,feldspar,clay,chert and opal.Cannel shales are usually dark brown or black shales,which consist of organic matter that completely enclos other mineral grains [7].Wang et al.[8]identify the mineral composition of oil shale from different locations and relate it to their interval of
occurrence.The physical and chemical compositions of shale oil,a complex mixture of hydrocarbons,depend on the source of the raw shale and the type of process ud to obtain the oil.It is well-known that liquid products from petroleum,oil shale and coal are difficult to characterize in terms of chemical structure,as they consist of large numbers of structurally diver compounds.Basically,shale oils differ from petroleum primarily in that they have higher nitro-
0016-2361/$-e front matter Ó2013Elvier Ltd.All rights rerved.dx.doi/10.1016/j.fuel.2013.05.055
Corresponding author.Tel.:+911292294235.
E-mail address:kumarr88@indianoil.in (R.Kumar).
gen content and as shale oils are produced by pyrolysis,they also contain some concentrations of olefins,which are generally found in natural crude oils in low concentrations.Shale oil rich in alkanes, cyclanes,arenes,as well as nitrogen-,sulfur-,and oxygen-contain-ing non-hydrocarbons;Hence,it is hard to analyze oxygen com-pounds in question without pretreatment of oils.Earlier traditional methods such as column chromatography and also dis-tillation were ud for the component analysis of oils.With the development of chromatographic paration methods,the molecu-lar constit
utions of shale oil and coal tar were gradually estab-lished.Zhu[9]parated two kinds of shale oils from mountainous area(land)and coastal shelf rock(a),both China, into four fractions using silica gel column chromatography.The components of each fraction were identified by GC–MS.The results show that shale oil from land contains269compounds,with abun-dant hydrocarbon compounds(79%),and some sulfur,oxygen and nitrogen compounds.Shale oil from a rocks contains284com-pounds with a high amount of hydrocarbon and oxygen com-pounds(60%and29%,respectively),and some sulfur and nitrogen compounds.Guo and Ruan[10]analyzed by GC–MS shale oils from Fushun oil shale of Liaoning province and Maoming oil shale of Guangdong province,both China.The main oxygen-con-taining compounds identified are phenols,diphenols,2-,3-and 4-alkanones,furans and benzofurans.Among the oxygen com-pounds,phenols constitute7–8wt%of oil(<350°C),the next most abundant being ketones.Bae et al.[11]compared the molecular compositions of two shale oils of oil shales from US Western and Russian mines,using15T FT-ICR MS coupled with ESI,and atmo-spheric pressure photoionization(APPI).Geng et al.[12]was per-formed,a comprehensive compositional analysis of the oxygen containing compounds prent in shale oil and low temperature coal tar using FT-ICR MS and GC–MS.Due to the prence of the components,shale oils are relatively thermally unstable[13],have poor long-term storage stability and require modifications of the analytical methods ud for petroleum characterization.
Estimation of oil shale rerves in India is greater than15billion tons.North-East India is endowed with rich deposits of coal,found in the Barail formation of tertiary age.Carbonaceous shale occurs interblended with the coal.The prence of coal and shale has been recorded in wells drilled for hydrocarbons by Indian companies. The formations outcrop on the surface towards the south of the oilfields in a region called the Belt of Schuppen.Studies have indicated that this oil shale constitute the principal source rocks that have generated the hydrocarbons produced from the region. There is no work reported on detailed characterization of Indian origin oil shale.
The prent work discuss in-depth characterization of Indian origin oil shale using analytical techniques such as CHNS analyzer, Induced Coupled Argon Plasma(ICAP),Gas Chromatography(GC), Infrared spectroscopy(IR),Nuclear Magnetic Resonance(NMR) spectroscopy and High Resolution Mass Spectrometry(HRMS). The study also focud on the molecular characterization of two shale oil samples obtained by retorting method from Indian origin oil shale.
2.Experimental
2.1.Samples
Oil shale samples S1–S7were obtained from Upper Assam Oil shale deposits and S8–S10from neig
hboring area in Arunachal Pra-desh shale deposits.Indian origin oil shales were dark brown or black in color.Shale oil samples are obtained by retorting method from oil shale S-7and S-10.Retorting of oil shale has been carried out at$500–550°C in Retorter pilot plant using CO2as sweep gas.Shale oil samples were obtained by condensing the oil vapors downstream of the retorter.
2.2.CHNS Analysis
Oil shale and shale oil samples were analyzed by CHNS analyzer Vario EL-III from M/s Elementar,Germany as per ASTM D5291 method.
2.3.ICAP Analysis
The ICAP spectrometer ud in this study was radial viewing Optima5300V from Perkin Elmer,USA.Deionized water of Milli-pore quality and Suprapure grades of hydrochloric acid,hydroflu-oric acid,AR grade of perchloric acid and multi-element standards in water matrix from E.Merck(Germany)were ud throughout this analytical work.
2.3.1.Sample and blank preparation
Sample($0.5g)was taken in platinum dish and ashed at650°C in muffle furnace to remove carbonace
ous matter prior to the acid digestion.To this,10ml each of hydrofluoric acid and perchloric acid were added and the contents were heated on hot plate till dry-ness to remove silica.To the residue obtained,20ml of hydrochlo-ric acid was ud to get it dissolved.The solution was transferred to100ml volumetricflask and made up to100ml with water. Blank solution was also prepared by following exactly the same procedure as for the sample.
In order to maintain the same acid concentration,stock solution of multi-element standard(100ppm)was diluted with blank to prepare1,5and10ppm standard solutions.The peaking of ICAP spectrometer was performed with Mn line(257.61nm)to cover all the elements.
2.3.2.Calibration and analysis
After spectral lines alignment using10ppm standard to cover all the elements,ICAP was calibrated using blank and1,5and 10ppm standard solutions.Blank subtraction mode was ud for the sample analysis for all analytes.
2.4.X-ray diffraction(XRD)
XRD studies were carried out in an18KW X-ray diffractometer (Rigaku,Japan).XRD patterns were re
corded at50kV and250mA, at a scan rate of1°/min with a step size of0.01°in the temperature range of2–75°2-Theta.XRD patterns were procesd for smooth-en,determination of inter-planner distance(d)of obrved peaks and arch match was conducted by using arch match softwares tofind out different compounds prent in the sample.
2.5.IR Analysis
IR spectra of the oil shale samples are recorded on Perkin–Elmer BX-II FT-IR instrument.Known weight($2mg)of the sample is mixed with100mg KBr and KBr pellet is prepared using the entire sample under5–8kg pressure employing a Hydraulic Press.The IR Spectrum of the KBr pellet is recorded at4cmÀ1resolution and100 scans were collected.The IR spectra were corrected for baline correction and smoothed to remove the noi and then analyzed for the prence of organic and inorganic moieties.
2.6.Open-column chromatography
The shale oil samples were fractionated into saturate and aro-matic fractions as per the ASTM-2549/91(reapproved1995) method.
R.Kumar et al./Fuel113(2013)610–616611
2.7.NMR Spectroscopic analysis
The1H/13C NMR spectra were recorded on a Bruker ACP-300MHz NMR spectrometer.1H,13C,Distortion Enhancement Polarization Transfer(DEPT-135)and Heteronuclear Single Quan-tum Coherence(HSQC)experiments were carried out using the pul quence of as per the experimental conditions described in our previous work[14].
访问的近义词2.8.MS Analysis
Samples of shale oil were subjected to high resolution mass spectrometry using Auto Spec Ultima HRGC–MS instrument.Ioni-zation was carried out at70eV electron ionization(EI).The mass spectrometer was t at6000resolution for detailed analysis of 22class of hydrocarbon.
3.Results and discussion
3.1.Oil shale analysis
3.1.1.Elemental and metal analysis
The elemental and metal analysis data of all oil shale samples studied are given in Tables1and2resp
ectively.The elemental analysis shows the prence of carbon(6–25%),hydrogen(0.6–2.5%),nitrogen(0.08–1.5%and sulfur(2–11%).The elemental com-position of an oil shale can be correlated with oil yields[15].Oil yields of Indian origin oil shale samples are calculated according equation given by Cook and are given in Table3.The oil yields of the samples S8–S10from neighboring area in Arunachal Pradesh shale deposits are found to be high(36.3–50.1GPT),whereas the oil yields of upper Assam Oil shale deposits ranges from12.8to 33.4GPT(S1–S7).The oil potential values reported in Table3(esti-mated according to Cook)are found to be very high as compared to actual reported oil potential of Indian origin oil shales.The oil yields are lower comparative to other known oil shales.
The organic carbon content is a good indicator of the quality of organic matter in the oil shale.Indian origin oil shale contains low concentration of carbonates and bicarbonates which are confirmed by ICAP,calcium(0.07–0.2%)and XRD.The comparison of XRD pat-tern of oil shale samples with XRD pattern of standard CaCO3con-firmed the low concentration of carbonate minerals in all the samples.Indian origin oil shale is siliceous in nature and found to contain siliceous minerals such as quartz and clay.Other major deposits of world oil shale viz.,Kukersite(Estonia),Jurf ed Dara-wish and the Sultani deposits(Jordan)[6]and Colorado,Utah, and Wyoming(United States of America)[4]are car
bonaceous in nature.Due to the prence of very low concentration of carbon-ates,it is confirmed that carbon(6–25%)in Indian origin shale is organic in nature.The samples are found to contain aluminum (2–7%range),ferrous(1.8–9%range),calcium(0.07–0.2%),sodium (0.1–1.05%)and potassium(0.4–1.23%)as major metals.A correla-tion among the iron content of the samples with sulfur content is obrved,indicating the prence of iron sulfide type component in all the samples.
3.1.2.X-ray diffraction(XRD)
XRD is one of the techniques normally ud for characterization of shale[16–18].A labeled XRD pattern of reprentative Indian origin oil shale sample is shown in Fig.1.The XRD spectra are re-corded using high power12.5kW,becau at high power even though the crystalline compounds prent at low concentration le-vel can give visible diffraction peaks in XRD pattern and there will no doubt to distinguish between peak and noi.From the XRD spectrum the most probable crystalline compounds prent in the samples are obtained by the arch match programme,which is bad on inter-planner distances(D)and intensity of peak(I)va-lue.There are many compounds having the same D value and arch match programme will not able to pin point the compound and give number compounds with matching index.XRD analysis showed the prence of both crystalline and amorphous pha in all the samples.Bad on the arch match analysis,the crystalline components
were identified as quartz(SiO2)along with kaolin clay (Al2SiO5(OH)4),Illite and pyrite(FeS2).The XRD pattern shown in this paper are smoothened one which clearly distinguishes noi from peaks of kaolin and pyrite as evidenced from clear peaks of at(2h)degree,12.3,20.3,24.8for kaolin and33.1,37.1,40.8, 47.4for pyrite.The intensity of the components was found to be different in all the samples indicating that%weight of the components varies from sample to sample.However,in all the samples Quartz was found to be the major component.XRD anal-ysis also indicated prence of small amounts of oxides of Iron in all the samples.XRD analysis indicated that SiO2was high in S-3while low in sample S-9.Clay was high in sample S-2and low in S-7.Hydrotalcite(magnesium aluminum hydroxy carbonate) was found in few of the samples(S-2,4,9and10)while this pha was abnt in S-1,3and8.XRD spectrum showed a broad weak hump in the two theta range20–30°,which indicates the prence amorphous material in oil shale.Generally,in XRD even for100% material amorphous material it gives broad weak diffraction peak, in two theta range20–30°.Therefore,the weak diffraction ob-rved in the prent samples may be due to shale oil prent in the oil shale,which is amorphous in nature.差旅一号
3.1.3.IR Spectral analysis
The IR spectrum of Indian origin shale is shown in Fig.2,which compris aliphatic and aromatic stret
ching and bending vibra-tions from kerogen overlapped with contributions from the miner-als prent,in particular silica and clay materials.IR spectra of all the samples indicate the prence of various sharp hydroxyl bands in3700–3600cmÀ1region(3693,3676.1,3651.2,3620, 3398cmÀ1)along with hydrocarbon bands in3000–2700cmÀ1re-gion.A sharp band at3697cmÀ1has been attributed to O–H of kaolinite,the sharp band at3625cmÀ1aris from illite in the oil shale[19].The broad O–H band at3380cmÀ1is also attributed to kaolinite,with possible contribution from moisture in the oil shale,absorbed during sample preparation.The broad O–H band obscures aromatic C–H vibrations,expected around3030cmÀ1. Aliphatic hydrocarbon stretching bands are obrved at 2930cmÀ1(m as CH2)and(m s CH2)[20].A small peak obrved at 1865cmÀ1is most likely an overtone or combination band of the silicate mineral fundamental.A shoulder obrved at1710cmÀ1, due to carboxylic acids in kerogen,is not completely resolved as a strong band at1640cmÀ1(aromatic and olefinic carbon–carbon double bond)overlaps.The broad band at1460cmÀ1aris from methyl and methylene deformation modes,with overlap from car-bonate minerals,if prent.The three unresolved bands at1190, 1160and1105cmÀ1are characteristic of pyrite.The bands in the region1000–450cmÀ1are due to clay and minerals in the oil shale
Table1
CHNS data of oil shale samples(wt%).
Sample Carbon(%)Hydrogen(%)Nitrogen(%)Sulfur(%)
S-1 6.1 1.20.08 2.3
S-214.0 1.90.4 2.2
S-38.6 1.40.4 2.2
S-615.4 2.0 1.5 3.6
S-711.5 1.70.6 4.9
S-816.7 2.10.610.3
S-922.9 2.7 1.0 2.4
S-1017.2 2.10.8 4.6
612R.Kumar et al./Fuel113(2013)610–616
and silica,with characteristic silicate vibrations occurring at 537and 470cm À1.The band at 2930cm À1is associated with aliphatic hydrocarbons prent in the sample and is assumed to be corre-lated with the sample’s kerogen content [21].IR Spectral analysis of the sample as such indicates the prence of inorganic materials such as silica,and clay (Kaolin Clay –Al 2O 3Á2SiO 2Á2H 2O)as major constituents.
3.2.Molecular characterization of shale oil
3.2.1.Elemental analysis of shale oil
Two shale oil samples were obtained by retorting method from oil shale S-7and S-10.The elemental composition of shale oil À7and 10,given in Table 4showing H/C ratio as 0.123and 0.124respectively,indicating that the Indian origin shale oil is carbon rich in nature and contains a significant amount of aromatics.The main characteristics of the organic matter of oil shale are high hydrogen and a low nitrogen percentage.Oil shale organic matter contains on average 2.1%of organic sulfur (Table 4).The sulfur content of the In-dian origin shale oil is low (1.9–2.3wt%),whereas deposits of Jorda-nian oil shale ranges from 0.3%to 4.3%.The sulfur content of shale oil from the Jurf ed Darawish and the Sultani deposits (Jordanian)is high (8–10%)[6]compared to Indian origin sh海参什么样的好
ale oils.One of the combustible components of oil shale is pyrite with the general chemical formula FeS 2.The sum of organic and pyretic sulfur is called combustible or volatile sulfur:The elemental composition and chemical nature (H/C ratio and hydrocarbon),of Indian origin shale oil is similar to Estonian (Kukersite)shale oil [22].
3.2.2.Estimation of total aromatic content by 1H NMR method
Estimation of the total aromatic content in the Indian origin shale oil sample using a 1H NMR spectrum is bad on the group molecular weight method and the determination of the relative number of carbon atoms.The philosophy of the group molecular weight method is to first assign the 1H NMR spectrum in terms of CH n groups (n =1,2,and 3)in order to calculate the relative number of carbon atoms.The latter part requires estimation of the quater-nary carbons and the average chain length of the substituents at-tached to aromatic rings.1H NMR spectrum of a reprentative Indian origin shale oil sample is shown in Fig.3.Various resonance signals assigned to different groups have been marked in the spec-trum.The complete assignment of the 1H NMR spectrum in terms of various hydrocarbon groups is included in Table 5.The assignments with regard to a -CH n (n =1–3)have been made by the application of 2D HSQC and 13C-DEPT-135NMR experiments.
Shale oil samples are rich in aromatics;especially,the di-ring plus aromatics are prent in an appreciable amount.The degree of substituents (r )and the chain length of the alkyl substituents on the aromatics depend on the boiling range of the sample.The total aromatic content,therefore,will be the contribution of the ring and the substituents.Knowledge about the average chain length attached to aromatics (other than a -methyl groups)de-
Table 2
Metal analysis data of oil shale samples (in%).Sample Al Ca Cr a Fe Mg Na Ni a V a K Zn a Ti a S-1 4.570.1053 2.240.140.2797<500.8111255S-2 3.670.1457 3.190.480.1481560.9160154S-3 3.680.0453 2.850.140.18<50<500.69<50108S-6 4.210.1979 2.680.130.1199560.9284183S-7 4.670.1163 5.320.230.16120520.9382137S-8 2.020.07<509.060.270.18115720.4783109S-9 5.070.10103 1.760.250.131861060.6782283S-10
3.78
0.10
74
4.35
提醒的拼音0.12
0.13
86
75
0.63
64
155
a
Values in ppm.
Table 3
独当一面的拼音Oil yield of Indian origin oil shale [calculated equation given by Cook (11)].Sample name Carbon (wt%)Oil yield (in GPT)S1 6.112.8S214.030.3S38.618.3
R.Kumar et al./Fuel 113(2013)610–616
613
解读象形文字noted as‘‘n’’is a must for estimation of the total aromatics using the prent methodology.The nature and average length of the al-kyl substituents greater than CH3groups cannot be estimated di-rectly,as their signals are merged with the signals of paraffins (0.5–2.0ppm)in1H NMR spectra.Besides this,knowledge about the contribution of substituted aromatic ring(ARs)and bridge-head aromatic carbons(ARb)is also required.However,the car-bons cannot be estimated directly fr
om a1H NMR spectrum be-cau they are non-protonated and not appear in1H NMR spectrum.
In the prent method,an indirect approach has been adopted to obtain information about the parameters:ARs,ARb,and‘‘n’’. The relative ARs carbons have been realized from the signals in the region2.0–4.0ppm assigned to a-CH3and a-CH2groups.ARb carbons have been realized by the developed equations.An average value of‘‘n’’has been estimated from the1H NMR spectral analysis of the pure aromatic fractions collected from open-column chro-matographic paration of a shale oil sample.After the complete assignment of the1H NMR spectrum has been made and the rela-tive contribution of ARs and ARb has been realized,the total aro-matic content of a sample can be estimated by the following equations.
Tc¼A=1þB=2þC=3þD=1:25þE=2þF=3þARs=1
þARb=1ð1ÞTw¼13ðAþBÞþ9Cþ13:25D=1:25þ7Eþ5Fþ12Â0:7Idð2ÞAw¼13AþnÂ7Bþ5Cþ12ARsþ12Arbð3Þwhere Tc,Tw,Aw,and n are the relative total carbons,total group molecular weight of the sample,total group molecular weight of aromatics,and average alkyl chain length of the alkyl substituents (other than methyl groups)on the aromatic rings.
The total aromatic content(A)of the sample(weight%)can then be estimated as
A¼100½Aw=Tw ð4ÞThe total aromatic content for the shale oil samples have been estimated from the developed equation and the data are given in Table4.
Table5
Divisions of1H NMR spectrum of Indian origin shale oil(for measuring integral intensity as per Fig.1).
Region (ppm)Assignment Integral
intensity
东北雪景普通话来源9.0–6.5CH of aromatics rings A 4.0–2.65a-CH2to aromatic rings B 2.65–2.00a-CH3to aromatic rings C 2.00–1.40CH,CH2of naphthenes,and iso-paraffins
(average CH1.25groups)
D
1.0–1.4CH2E 0.5–1.0CH3F 4.5–6.5CH of olefins
7.4–9.0di-plus aromatic rings Id
