Energy & Fuels 1988,2, 634-639
634
Iron-Catalyzed Gasification of Char in C 0 2 Edward Furimsky* and Paul Sears Energy Research Laboratories, Canada Centre for Mineral and Energy Technology ( C A N M E T ) , Energy, Mines and Resources, Canada, Ottawa, Ontario, Canada K I A OG1
Toshimitsu Suzuki Department of Hydrocarbon Chemistry, Faculty of Engineering, Kyoto University, Kyoto 606, Japan Received November 9, 1987. Revised Manuscript Received March 11, 1988 Gasification of Fe-loaded char was carried out a t 750 and 950 "C by using media containing 25, 50, and 100 vol 7% of C02. Mossbauer spectroscopy was used to determine the forms of Fe species present before and at the end of gasification. At 750 "C the reduction of magnetite by carbon was observed to be a rate-determining step. At 950 "C the gasification may be governed by a combination of mass-transfer effects and a loss of active Fe. At 950 OC both magnetite and wustite were present. The amount of the latter increased with decreasing C02 concentration in the gasification medium. ~
Introduction Iron-catalyzed gasification of carbon has been known for several decades.l McKee was the first to recognize that the catalytically active species was a metallic form of Fe.2 This state was approached when catalytic gasification was carried out in the presence of H2 An oxygen-transfer mechanism was used to explain the catalytic actions of Fe during gasification in C02 and H20.394 This involves a redox cycle in which metallic Fe is oxidized by COPand/or H20,yielding an iron oxide and CO and/or H2as products. The iron oxide is subsequently reduced by carbon giving CO and a catalytically active metallic form of Fe. These steps may be depicted as xFe
-
+ C02/H20 Fe,O
+C
Fe,O
xFe
+ CO/H2
+ CO
(1)
(2)
A temperature of at least 700 OC3 was required for Fe to have a noticeable catalytic effect. At this temperature the Fe oxidation reaction in C02was much faster than the iron oxide's reduction. However, the rate of the latter reaction increased with temperature. The temperature range of Fe-catalyzed gasification in steam was similar to that in C02.4 To ensure continuous catalytic action, the active Fe must exhibit some mobility. Otherwise the catalytic action would cease as soon as all carbon in the vicinity of the Fe is consumed unless diffusion of carbon to Fe takes place. These aspects of metal-catalyzed gasification were discussed extensively by Baker.5 Thus, Fe becomes mobile in contact with graphite a t about 700 "C. The mobility results in wetting and spreading of the metal on the graphite surface. This ensures an efficient contact between catalytically active metal and carbon. It appears that the presence of H2is not essential to maintain an active metallic form of Fe. It was shown by Kasaoka et al. that a t certain temperatures carbon is a stronger reducing agent of iron oxides than H2.6 Thus, Tudenham, W. H.; Hill, G. R. Znd. Eng. Chem 1955, 47, 2129. McKee, D. W. Carbon 1974,12, 453-464. Inui, T.; Otowa, T.; Okazumi, F. Carbon 1985,23, 193-208. Hermann, G.; Huttinger, K. Carbon 1986, 24, 429-435. Baker, R. T. K. In Carbon and Coal Gasification; Figueiredo, J . L., Moulijn, J. A., Eds.; NATO AS1 Series, Series E Applied Sciences-No. 105; Kluwer: Dordrecht, The Netherlands, 1986. (1) (2) (3) (4) (5)
0887-0624/88/2502-0634$01.50/0
during a temperature increase from 727 to 927 "C the log K values for reduction of iron oxides by carbon exhibited a dramatic increase in contrast to the small change of that for the reduction in H,.' Some evidence for Fe-catalyzed gasification in the absence of H2was presented by Suzuki et ala8 The catalytic effect of a lignite ash on steam gasification of an oil sand coke observed a t 930 "C and the absence of such an effect at 830 "C was also attributed to carbon participation in maintaining an active metallic form of Fe.9 The occurrence of Fe in several oxidation states suggests that a number of intermediate oxide forms may take part in the oxygen transfer betweeen Fe and carbon. This was indeed confirmed by Ohtsuka et al. during Fe-catalyzed gasification in H 2 0 and C02 in the 700-1000 "C range using an in-situ high-temperature XRD technique.lOJ1 Besides oxidic forms, Fe3C (cementite) and a- and y-Fe were also detected. The cementite may be a catalytically active form as was proposed by Holstein and Boudart.12 An electron transfer between Fe and carbon as part of the gasification mechanism was also proposed.13 However, solid experimental evidence supporting this mechanism has not yet been presented. The forms of Fe formed during high-temperature treatment of a graphite impregnated by an aqueous solution of Fe nitrate were investigated by Baker et al.14 Using the Mossbauer spectroscopy technique, these authors confirmed the presence of a- and y-Fe as the main Fe forms. The concentration of y-Fe relative to that of a-Fe increased with temperature of treatment. In the present work a series of chars was prepared a t different temperatures from an Fe-impregnatedbituminous coal containing a very small amount of sulfur. The reactivity of these chars was evaluated by introducing C 0 2 a t 750 and 950 "C in the absence of H2. The forms of Fe a t the beginning and (6) Kasaoka, S.; Sakata, Y.; Yamashita, H.; Nishino, T. Znt. Chem. Eng. 1981, 21, 419-434. (7) Barin, I.; Knacke, 0. Thermochemical Properties of Inorganic Substances; Springer-Verlag: West Berlin, 1973. ( 8 ) Suzuki, T.; Inoue, K.; Watanabe, Y. Chem. Express 1987,2,365. (9) Furimsky, E.; Palmer, A. Appl. Catal. 1986,23,355-365. (IO) Ohtsuka, Y.; Tamai, Y.; Tomita, A. Energy Fuels 1987,1,32-35. (11) Ohtsuka, Y.; Kuroda, Y.; Tamai, Y.; Tomita, A. Fuel 1986, 65, 1476-1478. (12) Holstein, W. L.; Boudart, M. Fuel 1983, 62, 162-166. (13) Long, F. J.; Sykes, K. W. R o c . R. SOC.London, A 1952,215,1001. (14) Baker, R. T. K.; Chludzinski, J. J.; Lund, C. R. Carbon 1987,25, 295-303.
Published 1988 by the American Chemical Society
Fe-Catalyzed Gasification of Char
Energy & Fuels, Vol. 2, No. 5, 1988 635
Table I. Properties of Coal (mfb) Proximate Analysis (wt %) ash 9.6 volatile matter 18.5 fixed carbon 72.3 Ultimate Analysis (wt %) carbon 81.2 hydrogen 4.3 sulfur 0.2 1.2 nitrogen oxygen (by diff) 3.6 Sulfur Forms (wt %) inorganic 0.18 organic 0.02
Table 11. Free Energies of Tentative Reactions Occurring during Fe-Catalyzed Gasification" -AG. kcal/mol reacn no. reacn 727 "C 927 "C Fe + Coz FeO + CO 0.95 1.92 2.05 4.04 3Fe + 4co2 Fe304+ 4CO 2Fe + 3c02 Fez03+ 3CO -5.33 -5.88 Fe304+ 4C 3Fe + 4CO 2.38 33.92 0.28 Fe304+ C 3Fe0 + CO 9.15 FeO + C Fe + CO 0.70 8.26 2.18 3Fe0 + COz Fe304+ CO 0.91 Fe3C + COz 3Fe + 2CO 1.49 9.57 3Fe + C Fe3C -0.39 0.09 "Note: FeO in the tables is wustite (Feo.M70).
at the end of gasification were determined by using Mossbauer spectroscopy. The gasification reactor used for the present work ensured a continuous withdrawal of reducing species such as CO and Hzin order to minimize their participation in reducing iron oxides to metallic Fe. Thus, another objective of this study was to confirm the catalytic effect of Fe in the absence of reducing species.
in the measured position of a single peak between the outermost iron peaks is estimated at h0.02 mm/s. The positions of overlapping peaks are less accurate.
Experimental Section Coal. The properties of the bituminous Balmer coal used in the present work are shown in Table I. The impregnation was performed by kneading the slurry of coal particles and an aqueous solution of Fe[NO3I3(4 w t % of Fe on the coal). The slurry was then spread on a metal plate and dried. Another method of Fe addition included mixing coal with Fez03 mechanically. Apparatus and Procedure. The fixed-bed reactor was a stainless-steel tube of 20 mm i.d. and was externally heated with a Lindberg furnace. The sample was supported on a 200 mesh sieve in the middle of the reactor. The gasification medium entered at the bottom, and products exited at the top of the reactor. The temperature was measured by two thermocouples placed near the bottom and the top in the center of the char bed. Experimenta were carried out with 10 g of impregnated samples (+20 to -10 mesh). The sample was held at 150 "C for 30 min in a flow of Nz(2 L/min) to remove the remaining moisture. The temperature was then raised to 950 "C and the charring continued for 30 min. The total weight loss that occurred during drying and charring was about 25% of the original coal load. The gasification run was begun by replacing N2 with the gasification medium. Usually, the temperature at the bottom of the char bed decreased on introduction of C 0 2 or H20; e.g., at 950 "C the temperature decreased to about 920 O C , indicating endothermic reactions. At the same time the setting of the automatic controller was increased to about 970 "C to offset the temperature decrease. After about 10 min the bottom temperature leveled off at about 940 OC, and that at the top leveled off at about 970 "C. At the end of the experiment the C02-containinggas was replaced by N2and the furnace raised well above the char bed. This ensured cooling the char bed to room temperature within about 60 min. The cooling rate gradually decreased with temperature. However, within the first 10 min, the temperature decreased from 970 to about 600 O C . Analysis. The gas exiting at the top of the reactor was split for simultaneous quantitative analysis using an on-line mass spectrometer and infrared analyzer. The data log system attached to the analyzers recorded product concentration every 60 s. The gas volume flowing per unit of time and product concentrations were used to calculate absolute and cumulativeyields of products. Mbssbauer spectra were run on Austin Science Associates equipment wit+ a 50 mCi 67C0in rhodium matrix source. A constant accelellation symmetric drive was used, and resulting spectra were recorded in a Canberra multichannel analyzer. A conventional nonlinear least-squares fitting program was used to fit Lorentzian lines to the digital data. The program combined the halves of the spectrum provided by the symmetric drive and provided for parabolic distortion of the base line. Calibration was provided by iron metal spectra, and all center shifta are given relative to the centroid of the six iron metal peaks. The error
--
-----
Results and Discussion Thermodynamics of Fe-Catalyzed Gasification. The reactions that may be part of the overall gasification mechanism and their AG values a t 727 and 927 "C are listed in Table 11. These results were calculated from data compiled by Barin and Knacke.' For carbon oxidation reactions the temperature increase from 727 to 927 "C resulted in a dramatic increase of the driving force compared with a much smaller increase for Fe oxidation reactions. The carbon oxidation may involve two consecutive reactions in which Fe304and subsequently FeO take part in oxygen transfer to carbon, i.e., reactions 5 and 6 in Table 11. This suggests that a coexistence of both oxides is possible. Cementite, if present, may also be part of an overall mechanism. Thus, the equilibrium constant for cementite formation is nearly one, and its formation cannot be excluded completely. It appears that oxidation of Fe to Fez03is not possible. The gasification rate may also be influenced by masstransport effects. For the Fe-catalyzed gasification both gas-solid and solid-solid reactions must be considered. The former are essential for Fe oxidation whereas solidsolid reactions play an important role during oxygen transfer to carbon. It is believed that for Fe oxidation the mass-transfer limitations are insignificant, especially at high COz concentrations. For solid-olid reactions, which dominate an oxygen transfer from Fe to carbon, the mass-transfer effects appear to be rather complex. Thus, after the carbon in proximity to Fe is consumed, a new contact must be developed either by diffusing C to Fe or wetting carbon by Fe, which requires a mobile form of Fe.' In the meantime, however, some Fe may have been converted to oxides. Then, the mobility of Fe oxides may also be important in maintaining catalyzed gasification. COz Gasification. Typical trends in CO formation during C 0 2 gasification are shown in Figure 1 where the zero time represents the point when the Nzflow was replaced by the flow of COz-containinggas. During the first few minutes the results were affected by the volume between the reactor and analyzer. The results in Figure l, together with the total gas flow per unit of time, were used to calculate the cumulative production of CO (Figure 2), which was used to calculate the instantaneous CO production rate (Figures 3 and 4). Instantaneous CO production rates were used to follow the effects of temperature and C 0 2 concentration on Fecatalyzed gasification. The results for Fe-loaded char prepared a t 950 "C and gasified a t 750 OC are shown in Figure 3. Initially high rates decreased sharply before attaining a steady state. From eq 1 and 2, the total CO
Furimsky et al.
636 Energy & Fuels, Vol. 2, No. 5, 1988
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0
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Figure 4. Change of instantaneous gasification rate with time (char prepared at 950 "C and gasified at 950 "C). Numbers in the agenda indicate COz concentration. achieved during impregnation compared with that for mechanical mixing. For Fe-loaded char prepared at 950 "C and gasified a t 950 O C the rate decrease in the course of gasification was much smaller (Figure 4) than that a t 750 "C (Figure 3). For the latter the steady-state gasification rate was nearly attained whereas that a t 950 O C was not. A t 950 *C the overall gasification rate was about 1order of magnitude higher, as indicated by large total CO yields (Table 111). Total CO yields in Table I11 may be used to estimate the number of redox cycles. For 50% COzgasification the estimate can be made from total CO yields for noncatalyzed and catalyzed gasification. Thus, by subtraction of
Energy & Fuels, Vol. 2, No. 5, 1988 637
Fe-Catalyzed Gasification of Char Table 111. Total CO Yields from Gasification of Chars Prepared at 950 O C (after 60 min of Gasification) yield at gasification COz concn in temp, mmol gasification medium, vol % 750 OC 950 O C 17.1 228.7 25 21.7 300.3 50 10.5 175.3 50a 6.3 54.4 50b 24.7 325.4 100 Coal admixed with FenOB. Yields for noncatalyzed gasification.
the CO yield for noncatalyzed from catalyzed gasification, the amount of CO produced via participation of active Fe species may be estimated. For one redox cycle involving the oxidation of Fe by C 0 2to Fea04and subsequent Fe304 reduction by carbon to metallic Fe and CO about 2.67 mmol of CO should be produced from 1.0 mmol of Fe. For about 7 mmol of Fe, one catalytic redox cycle should produce about 19 mmol of CO. At 750 and 950 "C about 15.4 and 245.9 mmol of CO, respectively, were formed. This translates to less than one and almost 13 redox cycles at 750 and 950 "C, respectively. Mechanism of Gasification. The number of redox cycles that occur during gasification may indicate the extent of mass-transfer effects on gasification mechanism. At 750 "C these effects should be insignificant. Thus less than one redox cycle should not cause any significant loss of contact between carbon and active Fe species. Also, for 50% C02 more than half of the CO was produced in Fe oxidation reactions as indicated by high rates during the early stages of gasification (Figure 3). The rapid decrease of gasification rates confirms that the reduction of Fe oxides by carbon is very slow and is a rate-determining step a t 750 "C. At 950 "C the presence of mass-transfer effects cannot be ruled out. High initial rates (Figure 4) confirm that gas-solid reactions involving metallic Fe are very fast. However, almost 13 redox cycles occurring a t 950 "C for 50% C02 may require an enhanced mobility of active Fe species and/or carbon especially a t later stages of gasification. A loss of active Fe due to sintering and agglomeration15 may increase the mass-transfer effects. In this case a portion of the bulk Fe may not be available for catalytic reactions. In other words, the oxygen transfer involving the outer surface of Fe particles will dominate catalytic gasification. Mossbauer spectroscopy was used to investigate the chemical form in which iron occurred in the samples. The spectra in Figure 5 are for chars prepared from Fe-impregnated coal by 30 min of charring at the indicated temperatures whereas those in Figure 6 are for residues obtained after 30 min of charring followed by 60 min of gasification in COP Fitted parameters from the Mossbauer spectra and those reported in the scientific literature for Fe forms identified in the present work are summarized in Table IV. The results in Figure 5 indicate the presence of three distinct species. There is a magnetic spectrum with center shift (cs) of 0.00 mm/s and a field of 330 kG. This may be attributed to metallic a-iron, probably in a martensitic phase, as the lines are in general somewhat broadened. An unsplit resonance at -0.09 mm/s is most likely due to an
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austenitic phase of metallic iron. A much weaker magnetic spectrum, of which only the +lI2 to +lI2and -'/2 to -'I2 lines may be clearly distinguished and the +'I2to +3/2 line appears as a shoulder on the +lI2to +lI2line of the first magnetic spectrum, has a cs of 0.18 mm/s and field of 206 kG. This corresponds very well to published data for cementiteI6 Fe&. The proportion of the austenitic or y-iron phase in the samples increased with temperature. The amount of cementite is always small, but is greatest in the 850 "C sample. For the gasification residues the distinctive spectrum of magnetite was present in every case. This was the dominant phase in residues from every run at 750 "C regardless of the C02 concentration in the gasification me(16) Preston, R. S.; Hanna, S. S.; Heberle, J. Phys. Reu. 1962, 128, 2207. (17) Cashion, J. D.; Aghan, R. L.; Doyle, E. D. Scr. Metall. 1974, 8, 1261-1265. (18) Shinjo, T.; Itoh, H.; Takaki, Y.; Nakamura, Y.; Shikazono, N. J. Phys. SOC.Jpn. 1964,19,1252-1253. (19) Bauminger, R.; Cohen, S. G.;Marinov, A.; Ofer, S.;Segal, E. Phys. Rev. 1961, 122, 1447-1450. (20) Baneriee, S. K.: OReillv, - . W.; Johnson, C. E. J. Appl. . _Phys. 1967, 38,'1289-1296. (21) Johnson, D. P. Solid State Commun. 1969, 7, 1785-1788. (22) Grant. R. W.: Wiedersich, W.: Muir, A. H., Jr.; Gonser, U.; Delgass, W. N. J: Chem. Phys. 1966,45; 1015-1019. (23) Greenwood, N. N.; Gibb, T. C. Miissbauer Spectroscopy; Chap man and Hall: London, 1971. '
(15) Huttinger, K. T.; Adler, T.; Hermann, G. In Carbon and Coal Gasification; Figueiredo, J. L., Moulijn, J. A., Eds.; NATO AS1 Series, Series E: Applied Sciences-No. 105; Kluwer: Dordrecht, The Netherlands, 1986.
Y
~~~
a
Furimsky et al.
638 Energy & Fuels, Vol. 2, No. 5, 1988 Table IV. Mossbauer Results
-0.09 0.18
measd as: m m / s 0.0 0.0 0.0
field, kG 330 0 206
cs, mm/s 0.0 -0.11 0.19
lit. as, mm/s 0.0 0.0 0.0
492 455
0.36" 0.6' 0.91 (0.86 1.27 1.09-1.18
0.0 0.0 0.46 0.78 2.73 highly variable
CB.
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A site B site FeOb
0.30 0.65
0.0 0.0
0.92
0.67
silicate/sulfate
1.14
2.72
0
field, kG 330 0 208 491 453 0 0 0 0
ref 16 17 18
19.20 19; 20 21 21 22 (FeSO,) 23 (silicates)
'Low-precision measurement (AO.1). bThe observed spectrum for wustite is an asymmetric doublet, which has been interpreted in a number of ways. In ref 21 the data are interpreted as two superimposed Fe" doublets as shown above, with a much weaker Fe"' resonance superimposed on the lower velocity peak. The relative intensities of the various components then vary with the exact composition of the material. qs = quadrupole shift. cn.nn.1
""&a,
high-spin Fe**compound, which may be ferrous sulfate though the measured cs is somewhat low. An iron(I1) silicate is another possibility. The ratio of the two oxides in the 950 "C experiments depended on the COz concentration. Figure 6 shows that the relative amount of wustite and the other ferrous species increased with decreased C02 concentration. The increased amount of wustite is consistent with the thermodynamic data in Table 11, which shoy that a lower C02/Fe ratio favors wustite formation. Comparison of the results in Figures 5 and 6 indicates an insignificant chemical change during the quench of gasification residues. Thus, the main reaction that could have occurred includes the reduction of Fe oxides to metallic Fe. For residues obtained a t 750 "C, the occurrence of such a reaction could not be confirmed. Also, no evidence for reduction of Fe oxides to metallic Fe was found for residues obtained a t 950 "C, though the possibility of magnetite reduction to wustite during the quench cannot be ruled out completely. However, a strong effect of C02 concentration on the content of magnetite and wustite in the residues suggests that the observed ratio of these oxides was attained during gasification rather than during the quench.
Conclusions
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-4
-8
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Figure 6. Mossbauer spectra of chars prepared a t 950 O C and gasified at 950 "C a t indicated C02 concentrations.
dium. There was also a small amount of absorbance at 0-1 mm/s, which is less easy to identify but may be due to wustite. At 950 "C, both magnetite and wustite were clearly present, the wustite appearing as an asymmetric doublet with cs of 0.92 mm/s and quadrupole splitting of 0.67 mm/s. Another doublet, with cs of 1.14 mm/s and quadrupole splitting of 2.72 mm/s, is due to another
The present experimental results support the oxygentransfer mechanism in which metallic Fe is oxidized by COz and subsequently reduced by carbon, yielding CO as the gasification product. This cycle re-forms an active Fe for another redox cycle. The rate-determining step of this mechanism is temperature dependent. Thus, a t about 750 "C, maintaining Fe in an active metallic form appears to be of crucial importance. Most of the studies published in the scientific literature, which indicate the Hz presence as an essential requirement for Fe-catalyzed gasification, were carried out at about this temperature. It is generally established that a beneficial effect of H2is evident only after its concentration in gasification medium exceeds a certain level. This suggests that H2 is adsorbed a t carbon sites, and only after such sites are saturated is the reducing action of H2observed. It should be noted that Fe-catalyzed gasification in the presence of H2 and/or CO in gasification medium has no practical application. At about 950 "C the catalytic effect of Fe is much more pronounced. Here, the reduction of iron oxides by carbon, which re-forms an active Fe, is rather fast because carbon is a much stronger reducing agent thant H2.6 It is assumed that a t temperatures approaching 950 "C the reestablishment of contact between carbon and iron oxides is the rate-determining step. The solid-solid reaction may be further affected by
Energy & Fuels 1988,2, 639-644 a loss of active Fe by sintering and agglomeration.
Acknowledgment. Part of this work was carried out under the "Japan/Canada Joint Research ProgramDeveloping Advanced Process for the Efficient Use of
639
Coal", sponsored by the Ministry of Education, Science and Culture, Japan. Registry No. FeO, 1345-25-1;Fe304,1317-61-9;Fe,Os, 130937-1; Fe, 7439-89-6; Fe&, 12011-67-5; COz, 124-38-9.
Performance of MoC1,-LiCl-KCl and NiCl2-LiC1-KCl Catalysts in Coal Hydroliquefaction with a Hydrogen Donor Vehicle Chunshan Song, Kouji Hanaoka, and Masakatsu Nomura* Department of Applied Chemistry, Faculty of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565, Japan Received February 29, 1988. Revised Manuscript Received June 2, 1988
The catalytic performance of MoC1,-LiCl-KC1 and NiC12-LiC1-KC1 salts in coal hydroliquefaction with the H donor tetralin was studied. Yilan subbituminous coal impregnated with the above catalysts and with LiC1-KC1 a t different loading levels (weight ratios of salts to coal of 0.1-1.0) was hydroliquefied a t 400 OC for 1h with an initial Hzpressure of 4.9 MPa. Increased loading of the MoCl, salt increased oil yield (up to 50 wt %), coal conversion, and H2 consumption, decreased the net hydrogen transfer from tetralin, and lowered the heteroatom content of oil. Addition of the NiC12 salt below a weight ratio of 0.2 led to more pronounced increases in oil yield, coal conversion, and H2 consumption and decreases in net hydrogen transfer from tetralin than with the MoCl, system. Higher loadings (>0.2) led to a small decrease in H2 consumption in spite of a further increase in oil yield (up to 50 w t %), implicating contributions of in situ formed H donors. The use of a LiC1-KC1 mixture slightly improved coal conversion while considerably suppressing H2 consumption. The relation between coal conversion and hydrogen consumption suggests that the action of the MoCl, and NiClz catalysts led to enhanced but selective hydrocracking reactions that contribute mainly to oil production. 'H NMR analysis of the oil revealed that hydroaromatic compounds increased and the average ring sizes of aromatics decreased with increased loading of the catalysts.
Introduction Numerous studies have been conducted of the application or improvement of existing catalysts and of the development of new catalysts for coal liquefaction.'-'l The (1)(a) Donath, E. E. Catalysis: Science and Technology; Anderson, J. R., Boudart, M., Eds.; Springer Verlag: West Berlin, 1982;Vol. 3,pp 1-37. (b) Weller, 5. W. Presented a t The 4th International Conference on the Chemistry and Uses of Molybdenum, Golden, CO, August 9-13, 1982. (c) Mochida, I. Shokubai Koza; Catalysis Society of Japan, Ed.; Koddansha: Tokyo, 1985;Vol. 9,pp 150-167. (2)(a) Lee, E. S. Coal Conversion Technology;Wen, C. Y., Lee, E. S., Eds.; Addison-Wesley: Reading, MA, 1979; pp 489-538. (b) Polinski, L. M.; Rao, V. U. S.; Stencel, J. M. The Science and Technology of Coal and Coal Utilization; Cooper, B. R., Ellingson, W. A., Eds.; Plenum: New York, 1984;pp 455-482. (3)(a) Tanabe, K.; Hattori, H. J. Jpn Pet. Inst. 1986,29,280-288.(b) Kamiya, Y.J. Fuel SOC.Jpn. 1979,58, 2-9. (4)(a) Kikkawa, S.;Nomura, M. Shokubai 1980,22,79-87. (b)Nomura, M.; Miyake, M. J. High Temp. SOC.(Suita,Jpn.) 1982,8,138-148. ( 5 ) Nomura, M.; Kimura, K.; Kikkawa, S. Fuel 1982,61,1119-1123. (6)Nomura, M.; Ikkaku, Y.; Nakatsuji, Y.; Kikkawa, S. J . Jpn. Pet. Imt. 1983,26,303-308. (7) Nomura, M.; Yoshida, T.; Morida, Z. Ind. Eng. Chem. Prod. Res. Deu. 1984,23,215-219. (8)Zielke, C. W.; Struck, R. T.; Evans, J. M.; Costanza, P.; Gorin, E. Ind. Eng. Chem. l'rocess Des. Dev. 1966,5,58-164. (9)Larsen, J. W.; Earnest, S. Fuel Process. Technol. 1979,2,123-130. (10)Grens, E. A., II; Hershkowitz, F.; Holten, R. R.; Shinn, J. H.; Vermeulen, T. Ind. Eng. Chem. Process. Des. Deu. 1980,19,396-401.
0887-0624/88/2502-0639$01.50/0
known catalytic materials14 include (1)metal oxides, (2) metal sulfides, (3) metal halides (molten salts), (4) metals and molten metals, etc. Two new coal liquefaction catalysts, MoC13-LiC1-KC1 and NiC12-LiC1-KC1 ternary salts, are effective hydrocrackingcatalysts for hydroliquefaction of a subbituminous coal without a vehicle.12 Differential thermal analysis indicated that these ternary salts exist in the molten state a t a coal liquefaction temperature of 400 OC. The catalytic activities for coal conversion and selectivity for oil formation of these MoC13- and NiClZcontaining salts are higher than those of the ZnC1,- and SnCl,-containing ones. ZnC12, SnC12,and their mixtures with alkali-metal chlorides are effective coal liquefaction catalysts."" Examination of these MoC13- and NiClZcontaining salts as catalysts for solvent-free hydroliquefaction of other brown, subbituminous, and bituminous coals also confirmed their high catalytic effectiveness for hydrocracking these coals and their high selectivity for production of oil (hexane ~ o l u b l e ) . ~ ~TemperatureJ~ programmed pyrolysis experiments revealed that these (11)Tanner, K.I.; Bell, A. T. Fuel 1981,60, 52-58. (12)Song, C.; Nomura, M.; Miyake, M. Fuel 1986,65,922-926. (13)Song, C.; Nomura, M. Bull. Chem. SOC.Jpn. 1986,59,3643-3648. (14)Song, C.; Nomura, M. Chem. SOC.Jpn.--Prepr. Symp. Pet. Chem. 1987,17,122-125.
0 1988 American Chemical Society
