Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 746-752
746
Hydropyrolysis of Hydrocarbons Marian Tanlewskl, Alfred Lachowlcz, Krzysztof Skutll, and Danuta MacleJko Institute of Organic Chemistry and Technology, SHesian Polytechnical UniversQ, 44- 100 Gliwice, Poland
The nature of hydropyrolysis, the effect of hydrogen on kinetics of pyrolysis, and its effect on the products distribution are discussed. The results of the studies on hydropyrolysis of the model fractions at atmospheric and increased pressure (1-31 atm) under various operating conditions in the presence of HP, H2-CH, and H,-CO mixtures are presented. The results of the investigations on the effect of hydrogen on secondary transformations of primary olefins and methylbenzenes under hydropyrolysis conditions are presented and discussed.
Nature of Hydropyrolysis An increase of the rate of a homogeneous free-radical chain decomposition of hydrocarbons can be achieved either by a change of the physical parameters or by introduction of suitable additives. The introduced substances may cause one or more of the following consequences (Taniewski, 1978): (1) rise of the rate of radicals formation and thus of rate of chain initiation; (2) rise of the rate of an overall chain propagation by generation of a new “additional” propagation route, in which the additive or the product of its transformation participates, and is consumed; (3) rise of the rate of an overall chain propagation by generation of a new “catalytic” chain in which the additive or the product of its transformation participates but is not consumed, thus playing a part of homogeneous catalyst. The first category of the consequences is typical for commonly used chain initiators easily decomposing into radicals which initiate the “normal” propagation p + RH +OH + Re R-
-+ /3
products
where /3 = small radicals and R. = heavy radicals. The second category (usually accompanied by the first one) is caused by a group of compounds XY (e.g., CC14) capable of generation another propagation step p + XY -* px + Y.
-
Y- + RH YH + R. R. + products The third one is caused by the additives HX with labile “active” hydrogen (e.g., HC1) capable of creating still another mode of “catalytic” propagation /3 + HX -* PH X*
+
+
X* RH HX + R. R- p + products
-
-+
Acceleration of the reaction by the two latter routes through the increase of the rate of propagation is, as a rule, more effective than by the first route which affects the initiation step. This is the case at least when the kinetic chain is long enough. To the last mentioned category belongs the catalytic activity of hydrogen (X = H) exerted on thermal decomposition of hydrocarbons. The effectiveness of hydrogen in stimulating the pyrolysis of some organic compounds (dimethyl ether, some individual hydrocarbons) was obsd. long ago (Benson and Jain, 1959). Only in recent years, however, has this effect been studied more thoroughly 0196-4321/81/1220-0746$01.25/0
(Kunugi et al., 1966,1967; Yokomori et al., 1976; Zelencov and Stepanov, 1975, 1976; Magaril and Ioanidis, 1975; Magaril and Polskaya, 1976; Zhorov et al., 1976, 1977; Rybin and Jampolskii, 1976; Zelencov and Jampolskii, 1977; Taniewski et al., 1980, and some others). The kinetic effect exerted by large amounts of hydrogen on the rate of hydrocarbon pyrolysis is generally attributed to the competition between a set of elementary reactions involved in “hydropyrolysis”
0 + Hz He
-
+ RH
/3H + H.
-+
Hz
+ R.
(1) (2)
and corresponding reaction of conventional pyrolysis /3 + RH -/3H + R. (3) By reaction 1 alkyl radicals are converted into much more active hydrogen atoms which attack hydrocarbon molecule in reaction 2. Reaction 2 is much faster than reaction 3 and thus the catalytic effectiveness of hydrogen can be estimated from the ratio of the rate constants k l / k 3 . Kinetics data show that both constants are of similar magnitude. Depending on the hydrocarbon, their preexponential factors are in the range of 10’1-10’2 cm3 mol-’ s-l and activation energies of 29-71 kJ mol-’. Hydrogen is therefore a genuine homogeneous catalyst of decomposition, though of a rather moderate activity. A large excess of it is required in order to exert sufficiently effective acceleration. Apart from its effect on kinetics of pyrolysis, hydrogen also strongly affects the products distribution. A marked increase of the yield of ethylene is often reported, which of course is of primary importance to the industrial prospect of the process. One of the possible reasons for the change in product distribution arises from the change in distribution of isomeric heavy radicals. This, in turn, is the result of different selectivities of alkyl radicals and of hydrogen atoms in reactions of hydrogen abstraction from various C-H bonds of the hydrocarbon molecule. Probably more important than this, however, are the changes in the nature and in the extent of secondary reactions. They arise from the increasing conversion of the feed in the presence of hydrogen and from the effect of hydrogen on primary products. A complex effect of hydrogen on chemistry of hydrocarbon pyrolysis involves, undoubtedly, such secondary processes as hydrogenolysis of olefm and aromatics (hydrodealkylation of alkyl aromatics),hydrodecyclization of polycyclic compounds and some others. On the other hand, the presence of hydrogen should retard such reversible reactions as dehydrocondensation of aromatics, dehydrogenation of alkylaromatics, dehydrocyclizations, etc. Hydrogenolyses of propylene, toluene, xylenes, etc. 0 1981 American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 747
were studied in the past mainly as independent reactions or those involved in hydrogasification processes. Not much is known, however, about hydrotransformations of primary olefins and aromatics under the conditions of hydropyrolysis, especially under pressure. Acceleration of pyrolysis, observed increase in the yield of ethylene, and reported decrease in the coke formation may allow to carry out the industrial process of hydropyrolysis in a kinetically less favorable region of increased pressure with the use of the heavy oil fractions as a feedstock. The chances to replace in this way the light hydrocarbon feedstock in the olefins production by heavier feedstocks, which are poorer in hydrogen content and more easily coked and which cannot be used in conventional tubular pyrolytic furnaces, make hydropyrolysis an attractive possibility. An increased pressure in hydropyrolysis seems to be justified both by technical and economical reasons. It leads to the reduction in dimensions of apparatus (particularly important in the case of the processes with diluents). It also prevents the necessity of compressing the gases before fractionation, etc. Several patents concerning the realization of hydropyrolysis have been published. There is also some information about a pilot-scale investigations of the process carried out in France at 1073-1273 K, 10-31 atm, and at a short residence time of about 0.1 s (Barre et al., 1976; Chahvekilian, 1977). The object of the present study was to investigate some general aspects of the specific role of hydrogen in pyrolysis and its effect on secondary transformations of primary olefins and methylbenzenes under hydropyrolysis conditions.
Experimental Section Two laboratory apparatus were used, one designed solely for atmospheric pressure experiments (apparatus I), the other for investigations under atmospheric or increased pressure (apparatus 11). Apparatus I was a conventional system containing a flow tubular quartz reactor (length 600 mm, i.d. 30 mm or alternatively length 100 mm) inserted into an electrically heated furnace. The temperature was regulated by standard temperature regulators and controlled by a moving Ni-Ni/Cr thermocouple placed in the reaction zone. The reactor was connected with a cooling and condensing system comprised of a water cooler, an alcohol-dry ice cooled trap, condensers, and separators. The continuous charging of liquid feed was performed by micropumps PD2 (Unipan, Poland) and measured by the thinner calibrated burets. The continuous charging of gases was performed directly from the gas cylinders equipped with the necessary measuring devices. Apparatus I1 was essentially similar to that described earlier (Taniewski et al., 1980) with only few modifications and improvements. It is shown schematically in Figure 1. It consisted of a flow tubular reactor made of a heat-resistant stainless steel H25T (Cr, 24-27%, Ni, 0.6%, Mn, 0.8%, Ti, 0.8%) with inner diameter 12 mm, outer diameter 20 mm, and the heated length 400 mm. The reactor was inserted in the three-section electrically heated furnace (4 kW) and connected to evaporator, preheaters, coolers, storage tanks, etc., as shown in Figure 1. In some experiments an additional tubular reactor was applied for continuous catalytic hydropretreatment of the feed before its hydropyrolysis. The analyses of gaseous products were performed by gas chromatography. An ICSO-5 gas chromatograph with TCD and a column with activated carbon (length, 0.7 m; i.d., 4 mm) was used to determine Hz, N2,and CO. A Pye Unicam Model 104 with FID and a column with alumina
t
I-
-J
Aedstock
MT
Yr
”
Liquid Products
Figure 1. Schematic diagram of apparatus 11: R, reactor; EF, electric resistance furnace; AC, air cooler; PC, preliminary cooler; PLT, preliminary liquid products trap; WC, water cooler; LT, liquid products trap; BF, bubble flash with water and cotton wool; GV, gas volumeter; PWG, preheater of water vapor and gas; WE, water evaporator; PP, feeding pressure pump; GFR, gas flow regulator; PR, pressure regulator; T, thermocouple; MT, moving thermocouple; B, buret; F, flowmeter; M, manometer.
modified by K&03 (length, 1.5 m; i.d., 4 mm), alternatively with a Perkin-Elmer chromatograph with FID and column with dimethyl sulfolane on Chromosorb P, 80-100 mesh (length, 10 m; id., 4 mm) were used for determining hydrocarbons. The liquid products were analyzed alternatively on a ICSO-571E chromatograph with TCD and column with Carbowax 20 M (length, 2.0 m; id., 4 mm) or on a Perkin-Elmer Model 900 with FID and a column with 15% polyglycol adipinate on Chromosorb WNAW, 80-100 mesh (length, 1.8 m; id., 4.6 mm). All reactants were commercial pure grade compounds of predetermined sufficiently high purity. A concept of the research was based on the principle of comparison of the results obtained in the presence of hydrogen with those obtained in the presence of nitrogen under identical operating conditions. It was believed that such a procedure would safeguard the minimalization of the experimental errors and improve the reliability of the results and of the conclusions.
Results and Discussion Hydropyrolysis and Pyrolysis of Model Fractions. As we have shown before (Taniewski et al., 1980), the accelerating effect of hydrogen on pyrolysis was observed with any of the different feedstocks and experimental conditions applied. Table I presents the excerpt from our results on comparative hydropyrolysis and pyrolysis of two model fractions of different origin and the properties, decomposed under various conditions. Fraction A (boiling range 447-608 K, C/H w t ratio 6.18) originated from Romashkino crude oil, fraction B (351-570 K, C/H 7.68)was obtained by hydrogenation of a coal extract. Table I in-
748
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981
Table I. Yields (wt %) of C, -C, Hydrocarbons in Pyrolysis and Hydropyrolysis of Model Fractions A and B fraction A fraction B 1:8or 1:3:5 mol 1:8 or 1:3:5 973K 0.7 s
1073 0.9 s 31 atm
1123K
1173K
3s
Is
39.6 47.3 42.4
35.8 39.1 45.0
20.0 21.5 22.4
21.5 30.4 25.8
51.6 51.7
66.1 61.7
63.2 45.7
70.9 54.4
diluent N2
H,O N* + HZO H2 H2 + H*O
Table 11. Yields (wt %) of Products in Pyrolysis and Hydropyrolysis (1073 K, 0.9 s, Feedst0ck:Water:Diluent = 1:3:5) of Kerosine Fraction (Boiling Range 447-608 K, mol wt 198, C/H= 6.18 wt) presdilu- sure, total total ent atm CH, C,H, C,H, C2 C,H, C,-C, N, + H,O H, + H,O
1 11 21 31 1 11 21 31
15.3 14.1 14.6 9.9 21.1 23.7 24.8 22.1
1.9 6.5 8.4 8.0
5.4 19.9 21.6 22.7
30.4 17.6 12.9 10.4 39.5 18.9 13.2 9.8
32.3 24.1 21.3 18.4 44.9 38.8 34.8 32.5
6.5 11.7 9.1 10.5 5.6 7.1 6.2 4.1
57.0 55.4 49.2 45.0 74.3 73.4 68.9 61.7
cludes only the yield of C1-C4 hydrocarbons treated as an indirect measure of a feedstock conversion in the decomposition processes. Irrespectively of the range of the absolute values of the yields, the replacement of nitrogen by hydrogen leads to appreciable rise in the yield. The effect of temperature on the rate of hydropyrolysis, appearing to be similar in its general trends to that of pyrolysis, was characterized by a set of results given in our previous work (Taniewski et al., 1980). Typical results on the effect of a rising pressure (1-31 atm) on the main products distribution are presented in Table 11. A positive kinetic effect of hydrogen is observed under all reaction pressures applied. The pressure increase is followed by an expected conversion decrease (the light hydrocarbons yield) both in hydropyrolysis and pyrolysis. The stimulating effect of hydrogen compensates, however, for the unfavorable effect of the increased pressure. For example, the total C1-C4 hydrocarbon yield in hydropyrolysis at 31 atm appears to be, under experimental conditions, higher than in pyrolysis under atmospheric pressure. In both processes the rise of pressure is followed by a decreasing yield of ethylene and of the total C2yield. The absolute value of the ethylene yield is at a low pressure region much higher in the case of hydropyrolysis than pyrolysis, but at a high pressure region the situation tends to be changed. The total C2 yield is higher in hydropyrolysis under any pressure. As the pressure is raised, the yield of ethane grows slightly in pyrolysis and rapidly in hydropyrolysis. Evidently, hydrogenation of ethylene occurs at higher pressures, changing the composition of the C2 fraction considerably. Hydropyrolysis at lower pressures therefore leads to a rise in the ethylene yield, as compared with pyrolysis, whereas at higher pressures it favors ethane formation. However, as the total Cz yield is much higher in the case of hydropyrolysis independently of the pressure, the process of hydropyrolysis coupled with subsequent pyrolysis of ethane always leads to a considerable increase of the overall ethylene production. The yield of propylene is somewhat lower in hydropyrolysis
I
I
-02 I
Of
05
I
I
a9 13 RESIOENCE TIME, S
I
17
J
Figure 2. The molecular hydrogen balance in hydropyrolysis (H) and pyrolysis (P)of n-heptane (1123 K, atm pressure, n-heptane: water:diluent = 1:4.5:6.2mol). Table 111. Hydropyrolysis of a Model Kerosine Fraction (Boiling Range 447-608 K, mol wt 198), in the Presence of Pure Hydrogen or Hydrogen-Containing Mixtures (1073 K, 0.9 s, Ker0sine:Water:Diluent = 1:3:5 mol) yield of yield of pressure, ethylene, propylene, diluent atm wt % wt %
NZ H2
H, -!- CH,, 57:43 dol H2 + CO, 51:49 mol
1 1 16 31 1 16 31
16 31
26.6 32.2 14.8 12.2 32.1 13.2 10.4 17.2 12.5
10.6 8.7 7.2 10.3 9.4 7.1 6.1 10.1 9.8
than in pyrolysis, which leads, particularly in view of the simultaneous rise of ethylene yield, to an increase (often desirable) of the ethylene to propylene ratio. The possibility of increasing the yield of the products desired from the feed of the low potential value by coupling its catalytic hydropretreatment (hydrogenation, hydrocracking) with hydropyrolysis into one continuous process was proved experimentally. In such a way, by pretreatment of a fraction B (673 K, 31 atm, catalyst) before hydropyrolysis (1073 K, 0.9 s, 31 atm) the yield of Czwas increased from 4.1 to 7.7 wt. 90. The catalytic effect of hydrogen does not anticipate its consumption (apart from some decrease in its formation through decomposition of C2H,. and other radicals). However, secondary transformations of primary products are highly hydrogen-consuming processes. As a result, a balance of molecular hydrogen in hydropyrolysis can be either positive or negative. This depends on the ratio of hydrogen-producing processes (primary decomposition of the feed) to hydrogen-consuming ones (secondary hydrogenolyses). Parameters of the process (especiallypressure) or conversion of the feed determine the net result of the balance. As an example, the comparative hydrogen yields in pyrolysis and hydropyrolysis of n-heptane under atmospheric pressure, at constant temperature, as a function of residence time are shown in Figure 2. The results of our experiments with a CH4-H2 mixture (being a model for a top product from demethanizing column of a gas fractionating unit) as well as with a CO-H2 mixture (representing a synthesis gas produced from coal
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 748 METHANE
0 1
1
I
8
I
ETHYLENE
ETHANE
I ;+-$
,
1
1
Id
I
CONVERSION
METHANE
1 1
I
I
~
Figure 4. Conversion of propylene and selectivity of the main products formation in hydropyrolysis (H) and pyrolysis (P)of propylene (1073 K, 0.9 s, 1:8:ca. 15 mol).
T.€MP€RATURE, X
1
!--4 -A-
TEMPERATURE, K
Figure 5. Conversion of C4hydrocarbons and selectivity of the main products formation in hydropyrolysis (H)and pyrolysis (P)of butene-1-butenes-2 mixture (4258, atm pressure, residence time 0.2 s, 1:lO:ca. 15 mol).
cases, the selectivity of formation of decomposition products is higher in hydropyrolysis, thus indicating that hydrogen suppresses the other routes of transformation. The effect of hydrogen on propylene transformation is, undoubtedly, one of the factors responsible for substantial increase of ethylene (C,)yield in hydropyrolysis. The purpose of the next series of runs was to confirm that effects observed in the case of propylene are more universal. This time a near-equilibrium mixture of butene-1 and butene-2 (4258) was used at atmospheric
750
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 I CONVERSION
ETHANE
~
METHANE
1.1
9 I
'T o# +i
CONVERSION
I
1
I-
ETHANE
f-
METHANE
TEMPERATURE, K
Figure 6. Conversion of ethylene and selectivity of the main prodand pyrolysis (P) of ethylene ucts formation in hydropyrolysis (H) (atm pressure, residence time 1 a, ethy1ene:water:diluent = 1:3:5 mol).
pressure. The results shown in Figure 5 fully confirm that hydrogen accelerates butene decomposition. Under experimental conditions, along with the rise of temperature in the range 873-1123 K, conversion of butenes rises rapidly from very low values to almost full transformation, both in pyrolysis and hydropyrolysis. Thus, the product distribution at low temperatures corresponds approximately to the primary reactions. At high temperatures advanced secondary transformations of primary products occur. Methane, propylene, butadiene, and ethylene are the major gaseous products in the pyrolysis of butenes. The selectivities of methane and ethylene formation grow monotonously with temperature (conversion). Those of propylene and butadiene proceed through a maximum, evidently due to secondary decomposition. Methane, propylene, and ethylene are the main products of hydropyrolysis. The selectivities of methane and ethylene formation again grow with temperature (conversion), but propylene formed initially with high selectivity rapidly decreases with the progress of reaction. Under any conditions hydropyrolysis as related to pyrolysis leads to an increase in the selectivities of methane and ethylene formation and to a decrease in the selectivity of butadiene (hydrogenation). Initial increase in the selectivity of propylene formation rapidly disappears in the course of reaction (hydrogenolysis). Both in pyrolysis and hydropyrolysis, ethane is formed in minor quantities. By analogy with a hypothetical mechanism of propylene transformations in hydropyrolysis, in the case of butenes the following set of additional elementary reactions responsible for the reported experimental findings can be postulated.
PRESSURE, atm
Figure 7. Conversion of ethylene and selectivity of the main products formation in hydropyrolysis (H)and pyrolysis (P) of ethylene 1073 K, 0.9 s, 1:6:11 mol).
lectivities of methane and ethane remain very low. In the higher temperature region the selectivity of methane (decomposition) slightly rises. Some other products (acetylene,butenes, butadiene) were also detected, but only in minor quantities. The change of pressure does not affect the ethylene conversion much. In the presence of H2at atmospheric pressure the contribution of ethylene hydrogenation increases considerably. Ita selectivity appears to depend strongly on temperature, and, as may be expected from its exothermicity, it falls down at higher temperature. The selectivity of methane formation rises considerably at higher temperatures. The growth of pressure is followed by a rapid rise in the rate of hydrogenation to ethane. Accompanying unsaturated minor products (see above) are formed in hydropyrolysis merely in negligible quantities. Hence we may conclude that in the region of lower temperatures and higher pressures of hydrogen, ethylene hydrogenation predominates among the reactions of ethylene. On the other hand, at higher temperatures and under lower pressures ethylene decomposition predominates. Summing it up, the higher the temperature, the lower the pressure, and the shorter the residence time, the lower becomes the ethylene to ethane conversion. It has been confirmed that in the presence of large amounts of hydrogen in pyrolysis, a substantial increase in the contribution of secondary transformations of higher olefins into lower ones, particularly into ethylene, with its partial hydrogenation, is observed. All observed transformations can be represented as follows.
H. f
C4H8
+
C4H9.
I H* feedstock
The possibility cannot be ruled out that in this case the real mechanism is more complex. In order to determine the extent of secondary transformation of ethylene, the next series of experiments was undertaken. The results of transformation in presence of H2or N2are illustrated in Figures 6 and 7. As it is shown, under any conditions, hydrogen as compared with nitrogen increases conversion. Its effect, though, under atmospheric pressure is much weaker than that observed with propylene and butenes. At low temperatures of pyrolysis it is not decomposition but some other reactions (probably polymerization, etc.) which predominate, whereas the se-
HZ
C2H4
-
C4H8
C2H6
IH2
C3H6
Some Secondary Transformations of Aromatics. The aromatic hydrocarbons may be both present in the feedstock and formed in hydropyrolysis. Among possible reactions (dehydrocondensation to diphenyl structures or to cumulated rings, hydrodecyclization with the rings opening, dealkylation, and dehydrogenation of the side chains, etc.) our attention was directed to the interconversion of aromatics by dealkylation. Under experimental conditions thermal hydrodealkylation of alkyl aromatics
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 4, 1981 751 80
1
01
HYOROPYROLYS/J
P
pyRoLysis
I
I
I
benzene in condensate,
m-xylene transformation
K
diluent
wt%
toluene in condensate, wt %
1023 1023 1073 1073 1123 1123 1173 1173
NZ HZ NZ H,
1 5 2 18 3.8 32.8 5.4 61.5
0.4 8.4 5.0 25.7 8.4 33.4 13.5 24.6
temp,
N,
H2
NZ H,
t
I
I
Table V. Transformation of Toluene (1073 K , Residence Time 0.9 s, To1uene:Water:Diluent = 1:3:5 mol benzene in the pressure, atm diluent condensate, % wt
Table IV. Transformation of Toluene and of m-Xylene (Atm Pressure, Residence Time 0.5 s, Aromatic:Water:Diluent= 1:6:9 mol) toluene transformation
1
benzene in condensate, wt %
0.3 0.4 3.6 0.8 14.7 2.4 41.5
and particularly hydrodemethylation obeying the stoichiometry is practically irreversible. Pressure change has no effect on its equilibrium, but positively affects ita kinetics. The particular importance of hydrodealkylation among the secondary transformations of aromatics arises from the fact that it leads to the change in the proportions between individual aromatics produced in pyrolysis. The results of our investigation concerning the extent of hydrodemethylation (as related to demethylation) of toluene and of m-xylene at the region of temperatures and pressures applied in hydropyrolysis or pyrolysis, are presented in Tables IV and V. In this series of runs we were not interested in the products other than simple aromatics (e.g., in diphenyl, dibenzyl, etc.). It is obvious, however, that hydrogen retards the reversible dehydrocondensation reactions. As is shown, hydropyrolysis involves the extensive hydrodealkylation of alkyl aromatics, especially in high temperature and pressure regions. Transformation of m-xylene to toluene is, as may be expected (Silsby and Sawyer, 1956), somewhat faster than that of toluene to benzene. Nevertheless, at higher conversions of m-xylene
1 1 16 16 31 31
N2 H* Nl H2 N2 H2
1.5 2.3 1.3 17.4 2.1 18.5
the mixture of toluene and benzene is produced. Extensive secondary hydrodemethylation should therefore affect considerably the composition of BTX fraction (benzene-toluene-xylene) produced in hydropyrolysis. Relatively more benzene should be produced in hydropyrolysis than in pyrolysis, as usually desired. In Figure 8 some results of the experiments with the BTX misture which show a remarkable change in its composition during the process of hydropyrolysis, as compared with pyrolysis, are presented. The reactions under consideration can be represented as
Conclusions Hydropyrolysis is a modification of a conventional pyrolysis. Due to the beneficial effect of hydrogen on kinetics of pyrolysis and ita effect on relative contributions of the primary and secondary reactions, hydropyrolysis opens the way to the possible usage of heavy hydrocarbon feedstock in olefin production, to the application of higher pressure, and to the relative increase in the yield of ethylene and of benzene at the expense of their homologues. Depending on the applied operating conditions the rise in ethylene production could be achieved either directly in one oper-
Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 752-755
752
ation or by combination with subsequent pyrolysis of ethane. Hydropyrolysis can be considered as a possible route for production of ethylene from heavy oil fraction as well as from the coal liquids produced by different techniques. The process can be coupled with preliminary catalytic hydrotreatment of the feed. Literature Cited Amano, A.; Uchiyama, M. J. Phys. Chem. 1963, 67, 1242. Bane, C.; Chahvekilian, E.;Dumon, R. H y d m h o n Process. 1976, 55, 176. Benson, S. W. "Thermochemical Kinetics"; Wiley: New York, 1968; Chapter 2. Benson, S. W.; Jain, D. V. S. J. Chem. Phys. 1959, 37, 1008. Benson, S. W.; Shaw, R. J. Chem. Phys. 1967, 47, 4052. Chahvekillan, E. Pet. Technal. 1977, 249, 82. Kunugl, T.; Tominaga, H.; Abiko, S.; Namatame, A. J . Insf. Pet. Jpn. 1966, 9 , 890. Kunugi, T.; Tominaga, H.; Abiko, S. "Proceedings, 7th World Petroleum Congress", Mexlco City, XX119; Elsevier: 1967.
Magaril, R. Z.; Ioanidis, N. V. Zh. Phys. Khim. 1975, 49, 293. Magaril, R. 2.; Polskaya, N. Ch. Neffeper. Neftekhlm. 1976, No. 5, 25. Rybin, V. Ch.; Jampolskii, J. P. Neftekhimiya 1976, 76, 729. Silsby, R. I.; Sawyer, E. W. J. Appl. Chem. 1956, 6, 347. Taniewski, M. Wiad. Chem. 1978, 32, 389. Taniewski, M.; Lachowicz, A.; Maciejko, D.; Skutil, K.; Fabisz, E. Neffekhimiya 1980, 20, 400. Yokomori, Y.; Arai, H.; Tominaga, H. "Industrial and Laboratory Pyrolyses", Albright, L. E.: Crynes, B. L., Ed., ACS Symposium Series 32: Washington, 1976. Zelencov, V. V.; Stepanov, A. V. Khim. Tiechn. 1975, No. 4, 18. Zelencov, V. V.; Stepanov, A. V. Khim. Tiechn. 1976, No. 7 , 59. Zelencov, V. V.; Jampolskii, J. P. Neftekhimiya 1977. 77, 734. Zhorov, J. M.; Vasiiyeva, I.I.; Panchenkov, G. M. Nefteper. Neftekhim. 1976, No. 8, 29. Zhorov, J. M.; Vasllyeva, I. I.; Panchenkov, G. M.; Kuzmin, S. T. Khim. Tiechn. Topl. Masei. 1977, No. 3, 9.
Received for review July 22, 1980 Revised manuscript received April 21, 1981 Accepted May 6,1981
Investigation of the Type of Saturated Paraffins Present in Kuwait Diesel Oil Mousa J. Ijam,' Mohamed A. Abu-Elghelt, and Mohamed A. Fahlm Chemistry Deparhnenf, University of Kuwait, P.O. Box 5969, Kuwaif
nParaffins in diesel oil (bp 21 1-370 O C ) obtained from Kuwait crude oil have been identified with the aid of gas chromatography/mass spectroscopy in combination with other operations as distillation, column chromatography, etc. The gas chromatography and mass spectroscopy made it possible to 'dentify 15 components of the n-paraffins, namely, C13-C27 and 25 branched paraffins, namely C1&7.
Introduction The influence of high molecular weight normal paraffins on the flow properties of crude oils and their effect on the qualities of a lubricating oil have made the estimation of these paraffins of importance to the petroleum industry (Brunnock, 1966). Furthermore, the determination of n-paraffins in complex hydrocarbon mixtures is of interest both academically and industrially. Academically, n-paraffin determinations are important in studies of the mechanism of chemical evolution of life processes on earth (Calvin, 1966). Industrially, a knowledge of the content and distribution of n-paraffins is often necessary in evaluating process concerned with changing the n-paraffinslbranched paraffins ratio of various petroleum fractions. The number of the homologous compounds and their isomers will increase by increasing their boiling point, which goes parallel with the increase of c number of a certain fraction. Hence the possibility of the isolation and identification of the constituents of high boiling fractions is a very complicated task. This problem was solved in the case of gasoline fraction. In the field of the analysis of kerosine, several important attempts have been made (Rossini et al., 1953; Rossini and Mair, 1959; Topchiev, 1955; Musaev et al., 1963). Recently published papers described the isolation and identification of paraffinic hydrocarbons from light and heavy kerosine obtained from Kuwait Oil (Ijam and AI-Zaid, 1977; Ijam et al., 1977). The aim of this work is to estimate and identify the type of paraffiiic hydrocarbons present in diesel oil (bp 211-370 "C) which will complete the normal paraffin profile of 0196-4321/81/1220-0752$01.25/0
Table I. Physical Properties of the Diesel Oil Distillate characteristics
values
B,, "C specific gravity, 60160 "F flash point, "F sulfur content, wt % viscosity (kin.), 100 OF, cSt ash content, wt % sediment by extraction, wt % aniline point, "C diesel index carbon residue (Conradson)
211-370 0.8473 166 1.44 4.3 0.01 0.01 71.8 57 0.84
crude oil and thus enable a better assessment of its potential as a feed-stock for the manufacture of biodegradable detergents and single cell proteins. Experimental Section Chemicals. Diesel oil (bp 211-370 "C) was obtained from Kuwait National Petroleum Company (KNPC) as a distillate fraction of crude oil. Its physical properties are summarized in Table I. Commercially available reagent grade solvents were used without further purification except drying (n-heptane, diethyl ether, chloroform, ethanol). Chromatographic grade silica gel (100-200 mesh) was the product of B.D.H. Chemicals Ltd. Poole, England. Instrumental. The UV absorption spectra were measured on a Pye Unicam SP-8O00. To determine the number of components in each sample a Hewlett-Packard series 5840 recording gas chromatograph equipped with a flame ionization detector was used. The column was stainless 0 1981 American
Chemical Society
