Revisla ~lexicana de Física 20 (971) FAI_ FA;FA!

RADIAllON TREATMENT OF PETROLEUM !\¡\lO PETROLEUII PIWDU( 1 S

l. - EFFECr OF OOSE ANO OOSE RATE ON CRUDE FHOM POZA RiCA!OROONEZ, PEMEX.

J 3vier Reyes Luján

Programa d, Aplicaciont*s Induslrialt*s y T(*cnológicas

Comisión Nacional dt* En,rgía Nuc/t*ar and Inslilulo d, Física,

{',litJ(*rsidad Nacional A.utónoma d, ,\féxico

ABSTRACT: The e{{eCI oE dose in Ihe radiolytical Irealmenl of rrulic oil is 10

in crease (he contenl oE heavy products, due lo th(-, reaclionsbctween the radiation •.induccd radical s (o form hydrnearbons withmolecular wei~hl higher than Ih(-,originals. Thc yidd of light

producls increases with dose ratc, due lo Ihc reaclioll!'> belWeetlIhc radicals and the atomic hydrogcn.

t:-.lTRODUCTIO:-.l

Ir has becn reporteJ 1 thar rhe radiation treatrn(:nt of erude ni! offers awide possibility uf applic<lrion, due to the developrnent of hi~h intcll .•••ity radi-ation sources. Sincc 1960, Ruskin2 obtained parcnts in th<.' (Jniled Srates andEngland. protecting a radiation process rhat increases rhe yield of severalfractions in rhe irraJiated crude oil wirh respect ro rhe non.irradiateJ sample.

\2Reyes I.uján

!Iow{"\'cr, no applicarion has beco developcd up lO {he present time. The faer,bar lhe composition of rhe crude oil affeets the radiolytical yiclds oC rheproducts3 might make ir possible rhat diffefl'llt results be cxpected foc differ-

tOnl samples of crude uiJ.The purposc uf (his papee is tu prcscnt sorne rcsults obtained in rhe

U('.l(m('nt of crude (lit from rhe fields of poza Rica/Ordóñcz, PE~IEX, sup-

plied hy (he Refinería u log. Antonio.\t. Amor", PEMEX, Salamanca, Gro.,wilh lhe characrcristics dcscribed elsewlH.'r(.l,

EXPERIMENTAL

Irradiation d~sigll and dosime-try. - Samplcs of 100 ce WCfC irradiatcd with 1.0.\Ie\' clecreoos froro (he Van de Graaff accclcrator. al the Instituto de Física,U:'\A.\I, using an irradiation ehamber descrihed in figure l. Thc exit of thischambcr was connect{,d lO a cold trap in ordcr ro collcct the light productsproduced during radiolysis, and to a gasmerer ro measure rhe gas cvolution.

Dosc rate was dctermincd by rhe usual tcchniquc4 wirh a valuc of682 rad/sec ¡..LA of clc:crron bcam currcnt. The variadon of rhe bcam currenrallows us ro study the eHecr of dose rat{o. During irradiarions rhe rempera.ture of rhe sample was H.'corded continuously,

Ana/ytica/. - Samples of 80 ce of rhe irradiateo and non.irradiarl'd productswerc disrillcd by the convenrional rcchniques in rhe following ranges:

l. - Room tempcrature (RT) to I80°C, atmospheric prcssure (mm);

11. - 180-220 o C. atm ;

1II. - 220-300 o C. a tm ;

1\'.- 300-4000C, atm;

V. - RT-2000C, with maximum pressurc of 1 torr and

VI. - 200-3000C, 0.05 torro

The distillcd samp!es V and VI were cleaned by a rcdistillation.Thc distillcd products were then analizeo by GL chromalop:raphy u.'iing

a Varian Aerograph, moo(o¡ 1200, with the characteristics oescrib(,d dSl"whcré.

-Lab'oratory operated by Pro~rama de Aplicaciones Industriales y Tecnoló~icas,C~E~ and Instituto de Física, UNA~t.

Radiation Trratrnpnt o/ Pl'troleurn FA3

6- - - -

7

12

Fi~.l. Scheme (\f rhe inadiarion system used for the experiments. The electronlwam C'1l(crS rhe irradiation chamber through a 60 microos thick tiraniumwindow \ j) where r!-¡e crude oil'(S) is .stirred with a glass.covcred ma~net(7). Thc..'ctlamber v.as mOlde with Pyrex recipienr ~6) an~ a brass cap (.1),••ealed bar!-- with Epoxy resin (3). The [iramum v.lnJow lS sealed by meansuf O'ring. The exir of the chamber (H) is cono.ected through a val~'e (y~ toa solid cacbon dioxide cold tcamp, whcre [he ltghr products of radlOlyslsart:>colleeted (11). The volume of rhe ¡;;aseous products are measured bya ~asmeter (12).

RESUL TS ¡\NIl IllSCUSSIOl\'

The ..•ampIes of crude were irradi<lted at.\trad, distiIled at differenc ranges and each range1'he chrollluwgrams obtained for samples of meracion in more than 60 individual hydrocarhons.hydrocarhons of the irrad iated samples were theirradiared one.

doses uf 100, 500 and 1000analyzed by chromatography.ranges 1 [() IV, show a sepa.1'he distribucion of thesesame than chose of the non-

Hlf~ct o/ dos~, - Figure 2 shows the rel,Hinn hetwe(.n dose and the yield ofthe di."i(ill,uion fractions, for experiments con<lucted at adose rate uf13.65 Krad/sec. 1t is clcar that rhe u\'<-'full cHect of dose IS to ¡ncrease [hecontent uf heavy products.

FM

'0

,o

20

",o

Reyes Luján

"'.lDOS£. (M,adl

• orz¡ '00

O "'"I'!l 000

P,n""'t (lord

* I•• oo~

220-300

Fi~. 2. Relation betw{"eo dos(' and [he yicld oC (he distillation fractions obtainedfor [he radiolysis at a dos(' rau. oC 13.65 Krad/s{'c.

This rcsult may be explained by the following modcl. Irradiationproduces rupture of the C-IJ and C-C bonds uf rhe hydrocarbons rnolecul{'s(~t) forming atomic hydrogen and free radicals.

~l

M , RI

+

+

'11

, R2

( 1)

(2)

where R ami R arc radicals with different number of carbons.1 2rhe most probable reactions of rhese active species are:

i) rhe recombination o( rhe acomic hydrogcn and [he parent radical,to give again [he hydrocarbon molecule,

+ , 1I ~I

ii) rhe recombimHion uf rhe [wo fonned radical s lo give again rhehydrocarbon molecule

Radíalíon Trealmpnl 01 Pelro/f?um FA5

'RI

+ 'R2 (4)

iii) rhe reacrion of rhe rwo atomic hydrogens ro give molecular hydro-gen,

'11 + '11 (5)

iv) rhe rt.'acrion berween rhe aromic hydrogen and rhe radicals ro givehydrocarbons,

'11 + , R (or' R )I 2

• N (6)

where rhe number of carbons of rhe producr N (~) is less rhan rhe number ofe~rbons of rhe original molecule .\1, (n.\f).

v) rhe reacdon berween rhe formed radicals ro give hydrocarbon mole-cules,

'R1

'1{2

+

+

• R1

"R2

• N

• L

(7)

(8)

The evolurion of molecular hydrogen is observed during rhe irradi-ation and also in rhe distil1ation of the irradiared samples, and rhe rotalvolume inereases wirh dose, so reaerion (5) should be imporrant in rhe wholeproeess. The incremenr in rhe eonrenr of heavy produers with close, allowsus ro eonsider reaetion (8) as, al so, an importanr par~ of the proeess. Asracliolysis proeeecls (close increases) these rwo proeesses become more im-porrant.

F.11~et01 dos~ rat~. - The cffcer of rhe close rare was srudied in rhe rangeup ro 82 Krad/scc; rhis upper limir is given by rhe aeceleraror powcr obrainedfor rhe particular irradiadon design seleered. Figure 3 shows the relationberween dose rare and rhe yicld of rhe distillarion fracrions for a fixed doseof 100 Mead. As the dose rate ¡ncreases rhe producrion oí heavy productsdecreases and rhe yield of light producrs starts ro increase. A e€frain amountoí lighr producrs is collecred in the eold rrap connectcd ro rhe irradiationehamhcr, due ro rhe faer that rhe intense bcam eurrenr ¡ncreases rhe rempera-

FA6

(ure of (he samples up to 100 oC.electron beam proccss, du(' {() (he

irradiation.

Reyes Luján

This result offers a wide possibility forscpararion of light fractions at (he time of

, Vi •••

"'O

"'O

"

'O

DOS[ 100 MrodOO( 1•.•,1• COI'Iffol

¡;¡ IlISO

O ..,~D 8.,01.2

220-500 300-400 <200. '"'soo.. "£$IDUE f"'CI

Fig. 3. Relation betwecn close rate and (he yield oC (he distillation fractions oh .•tained Cor the radiolysis at a close oí 100 Mrad.

The Caer thar rhe yield of (he light products ¡ncreases with close rate?allows liS to consider that feaetioos (6) and (7) become more impocrant. The¡ncrease of close cate an'd tcmpcraturc during irradiation gives more energy tuthe free radicals and rhcir probability of reaetion with (he atomic hydrogenand other radicals ¡ncreases due to their greater rnobility.

CONCLUSIONS

Cornrnercial clectron accelerators designed fm industrial processcswith electron bcam currcnts up to la mA have bccn dcvcloped by severalcompanies7, so it will be posslble in the::futurc to (ncrease research in radi.ation cracking of crude oils with intcrest for pctrolcum companies.

Radia/ion Trf"a/mpn/ 01 Pe/ro/pum

ACKNOWLEDGEMENTS

FA7

The author is particularl)' grateful to associates of th" AcceleratorLaborator)' for their ~ssistance in the experiments; to Refinería" Ing. AntonioM. Amor", PEMEX, Salamanca, Gto., for supplying the samplcs and to A.Valladares for proof.rcading the manuscript.

REFERENCES

1. J. Reyes L., u Raoiólisis de productos del petróleo", Rev. Mex. Fís. 19(970) FA l.

2. S. L. Ruskin et al, "Trcatmcnt of petrolcum and pctroleum products byirradiation", Brit. Patcnt 88l 492 (961); e. Catalytic conversion ofpctroleum", USA parent 2953509(960).

3. E. F. Baxter and J. F. Black, "Effect of radiation on petroleum anO itsproducrs", USA AEC ESSO-~IA-I (1959).

4. J. Rcyc, l. ..• Radióli,i, del crudo PE~IEX", Proyecto 69.1, RcporteNo. 1, PAIR, OiEN, Diciembrc (1969).

5. J. ReYl's L., '.Radiólisis del sistema heterogéneo óxido de aluminio.heprano", Pr"yccro 70.A, Reportc No. 1, PAIR, CNEN, Abril (1970).

6. R. Montiel C., "Radiólisis del n+leptano", Tesis Profesional,Faculrad dc Cicncias, UNA~I (1970).

7. ••Large radiation sourccs for industrial processes", International AtomicEnergy Agcncy, Vicnna, STI/PUB/236, (1969).

RESUMEN

!.:i efecto principal de la dosis en el tratamiento radio lítico del crudoes aumentar el contenido de productos pesados, debido a las reacciones en.tre los radicales inducidos por la irradiación, las cuales dan lugar a hidrocar-buros con mayor peso molecular que los originales. El rendimiento de ft'oduc.tos ligeros se incrementa con la razón de dosis, debido principalmente a lasreacciones entre los radicales y el hidrógeno formado.