Energy & Fuels 1990,4, 197-201
197
Mo-A1203catalysts using the pulse microreactor technique
cluding Ti0,S and/or AlO,S,, and/or elemental sulfur. Thus, the excgange data must be evaluated in the light of uncertain sulfide compounds and stoichiometry. First we note that the assumption that organic sulfur compounds derived from the coal/solvent are adsorbed on the catalyst only makes the problem more perplexing. The sulfur compounds derived from the coal will have a b(34S) value of 2.5; correcting the 6(%3) values of the catalyst for any coal derived from adsorbed organosulfur compounds decreases the amount of sulfur that rapidly exchanged. If we assume that Ni and Fe are present as NiS and FeS and that these exchange rapidly, we can account for only 43% of the total rapid exchange; assuming only NiS is formed and rapidly exchanges can account for about 39% of the total rapid exchange. If it is assumed that (1)MoS2 is formed and does not exchange rapidly and (2) all other sulfur is present in a form that rapidly exchanges, then the rapid exchange should be 27.8% of the total sulfur rather than the 34.5% that is observed. The data are suggestive that a significant fraction of the sulfur present in “molybdenum sulfide” does not exchange rapidly. To define the source of the rapidly exchanging sulfur will require further work with a series of sulfided preparations: alumina only, Mo-A1203, Ni-A1203, Ni-Mo-Al,O,, etc. Isagulyants and c o - ~ o r k e r s ~utilized ~ J ~ the 35Sradioisotope to follow the exchange of sulfur isotope in Co-
and lower temperature and pressure conditions. They found that about 60% of the sulfur in the catalyst is not involved in exchange during the conversion of thiophene. More recently Dobrovolszky et al.l8utilized a pulse reactor at low-pressure conditions to follow the retention and exchange of radioactive sulfur with nonradioactive sulfur during the conversion of thiophene. These later workers found a release of about 20% of the sulfur added to the catalyst was removed during subsequent reactions. The present results, obtained at high pressure in a large 6 ton/day plant, show remarkable agreement with data reported for small-scale, low-pressure laboratory reactors. It is apparent that stable sulfur isotopes can be utilized in appropriate situations even in large-scale reactors and at industrial/process conditions. The efforts expended in catalyst preparation and pretreatment to produce highly dispersed sulfided molybdenum species appear to be merited since at least two-thirds of the sulfur initially present in Ni-Mo-alumina catalysts exchanges very slowly. This is taken to indicate that the small molybdenum sulfide crystals retain their original structure for long time periods (days or months); if rapid reorganization of these crystals were to occur, it is expected that sulfur exchange would quickly occur between the sulfur present in the reactant and the sulfur pool initially present in the catalyst.
(16) Isagulyants, G. V.; Greish, A. A.; Kogan, V. M.; V’yunova, G. M.; Antoshia, G. V. Kinet. Katal. 1987, 28, 632.
Acknowledgment. The operators of the Wilsonville, AL, pilot plant have been exceptionally helpful by providing samples as well as advice and guidance.
(17) Isagulyants, G. V.; Greish, A. A.; Kogan, V. M. In Catalysis. Theory to Practice (Proceedings of the Ninth International Congress on Catalysis);Phillips, M. J., Ternan, M., Eds.; Chemical Institute of Canada: Ottawa, ON, Canada, 1988; Vol. 1, p 35.
(18) Dobrovolszky, M.; Tetenyi, P.; Paal, Z. Chem. Eng. Commun. 1989, 83, 1.
31PNMR Spectroscopic Analysis of Labile Hydrogen Functional Groups: Identification with a Dithiaphospholane Reagent C. Lensink and J. G. Verkade* Department of Chemistry and Ames Laboratory, Iowa State University, Ames, Iowa 50011 Received November 27, 1989. Revised Manuscript Received January 29, 1990 Six chlorophospholanes (2-7) are evaluated as 31PNMR tagging reagents for labile hydrogen functional groups known to be present in coal materials. In this series, 2 (C1PSCH2CH2S)is demonstrated to be best for resolving the 31PNMR chemical shifts of a variety of model compounds within a given functional group class, as well as for the separation of the shift ranges among the various classes. I
Introduction In our quest for appropriate NMR-active derivatizing reagents for the NMR analysis of labile hydrogen functional groups in coal materials, we have in recent years been exploring a series of 1,3-dioxaphospholanes,of which 1,3-Dithiaphospholanes(2-4) appeared 1 is an e-ple.1-3 (1) Schiff, D. E.; Verkade, J. G.; Metzler, R. M.; Squires, T. G.; Venier, C. G. Appl. Spectrosc. 1986.40, 348. (2) Wioblewski, A. E.; Markuszewski, R.; Verkade, J. G. Prepr. Pap.-Am. Chem. SOC.,Diu. Fuel Chem. 1987, 32, 202. (3) Wroblewski, A. E.; Lensink, C.; Markuszewski, R.; Verkade, J. G. Energy Fuels 1988, 2, 765.
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i
to be able to yield improved 31PNMR peak resolution for differentiating various compounds within a functional group class, according to preliminary results we obtained with 2.4 Herein we report in detail our findings with 2 and a comparison of the substituted derivatives 3 and 4 as reagents. We also evaluate reagent 5 in order to test the effect of the absence of heteroatom substituents on phosphorus and reagents 6 and 7 (on which we had reported in preliminary form4) to determine the influences (4) Lensink, C.; Verkade, J. G. Prepr. Pap.-Am. Fuel. Chem. 1988,33, 906.
0 1990 American Chemical Society
Chem. SOC.,Diu.
198 Energy & Fuels, Vol. 4 , No. 2, 1990
Lensink and Verkade
of steric hindrance and ring size, respectively.
Table I. Chemical Shift Ranges (ppm) for Model ComDounds Derivatized with Reagents 2-7
reagent 2 3 4 5 6 6
5
7
7
Since our last report, in which the previous literature on tagging labile hydrogen functional groups with NMRactive nuclei was summarized? the results of experiments using Ph2P(0)C1as a reagent have been described? This reagent does not resolve the 31Pchemical shifts for variously substituted phenols, however, and the thrust of that work was directed at determining a total phenolic -OH content.
5
0
alcohols acids amines 143.4-146.0 152.2-159.8 91.4-103.9 151.8 144.9-158.5 138.3-149.7 154.9-164.1 170.5-174.0 144.6-154.4 144.5-151.0 61.0-78.2 131.2-138.4 124.3-133.1 130.3-132.7 146.1-152.5 141.5-154.4 135.8-141.5 76.0-131.8 phenols 152.1-167.4
-c1
Experimental Section Reagents. Triethylamine was distilled from KOH pellets and kept under nitrogen. Chloroform-d was used as received. Samples
of the model compounds (substituted phenols, alcohols, carboxylic acids, amines, and thiols) were purchased from various sources and used as received. The reagents 1,6 2,' 5,s 6: and 71° were synthesized according to published procedures. meso -2-Chloro-4,5-dimethyl- 1,3,2-dithiaphospholane (meso-ClPSCHMeCHMeS, 3). A solution of meso-2,3-butanedithioll' (3.80 g, 31.1 mmol) and NEt3 (6.30 g, 62.2 mmol) in diethyl ether (25 mL) was added dropwise to a solution of PC13 (4.30 g, 31.1 mmol) in EhO (125 mL) and methylene chloride (25 mL) cooled to -40 O C . The reaction mixture was allowed to warm to room temperature and was left stirring for 3 h. A precipitate of Et3NHClwas removed by filtration, and the solvent was removed under reduced pressure. Vacuum distillation yielded pure 3 (1.3 g, 6.9 mmol) as a colorless, moisture-sensitive liquid: bp 52-54 OC/O.O5 mmHg; 31PNMR (CDC13)170.21 ppm; 'H NMR = 6.6 Hz), 4.19 ppm (2 H, m); (CDCl,) 1.39 ppm (6 H, d, 3JHH 13C NMR (CDC1,) 16.1 ppm (CH,), 57.8 ppm (CHMe). dl-2-Chloro-4,5-dimethyl-1,3,2-dithiaphospholane( d l ClPSCHMeCHMeS, 4). A solution of dl-2,3-butanedithio111 (6.93 g, 56.7 mmol) in methylene chloride (20 mL) was added dropwise to a solution of PCl, (7.80 g, 56.9 mmol) in methylene chloride (100 mL) at room temperature. The reaction mixture was left stirring overnight while a slow stream of nitrogen was bubbled through the solution. Removal of the solvent followed by vacuum distillation yielded 4 as a clear liquid bp 49.5-50.5 OC/0.05 mmHg; 31PNMR (CDCl,) 163.95 ppm; 'H NMR 1.52 ppm (3 H, d, 3 J c -H~ = 6.7 HZ), 1.58 ppm (3 H, d, 'JCH~,-H~ = 6.7 HZ), 3.62 ppm (1 k, m, 3JH-H, = 9.0 HZ, 3JpH = O HZ), 3.93 ppm (1 H, my 3JH-Ht = 9.0 HZ, 3JpH, = 1.2 HZ). 31PNMR Spectroscopy. 31PNMR spectra for model compounds derivatized with reagents 2-7 were recorded on a Bruker WM-300 spectrometer operating at 121.5 MHz. Chemical shifts of the respective derivatives are expressed in parts per million relative to 85% H3P04. In a typical analysis, an NMR tube (10 mm) was charged under N2 with the reagent (0.20 mL), chloroform-d (2.0 mL),and triethylamine (0.3 mL). The reagent solution was reacted with model compounds and the 31PNMR spectra recorded. I
.
I
(5) Dadey, E. J.; Smith, S. L.; Davis, B. H. Energy Fuels 1988,2,326. (6) Zwierzak, A. Can. J. Chem. 1967, 45, 2501. (7) Denney, D. B.; Denney, D. 2.; Liu, L. T. Phosphorus Sulfur 1985, 22, 71.
(8) (a) Somner, K. Z . Anorg. Allg. Chem. 1970, 379, 56. (b) Wolfsberger, W. J. Organomet. Chem. 1986, 317, 167.
(9) Ramirez, F.; Patwardhan,A. V.; Kugler, H. J.; Smith, C. P. J. Am. Chem. SOC.1967,89, 6276. (10) Nifantiev, E. E.; Sorokina,S. F.; Borisenko, A. A.; Zavalishina, A. I.; Vorobjeva, L. A. Tetrahedron 1981,37, 3185. (11) Iqbal, S. M.; Owen, L. N. J. Chem. SOC.1960, 1030.
60
70
80 90 100 110 120 130 140 150 160 170 3 ' P Chemical S h i f t (ppm)
Figure 1. Ranges of 31PNMR chemical shifts for model compounds derivatized with reagents 2-7.
Results and Discussion Derivatization. The reagents 1-7 react easily with labile hydrogen functional groups according to reaction 1 Et,N + -QH + ClP< -QP< + Et,N*HCl (1)
-
wherein -QH represents a labile hydrogen functional group (e.g., -C02H, ROH) and ClP< denotes one of the reagents. The newly synthesized reagents 3 and 4 have physical properties similar to those of the analogous reagent 2. All of the reagents are sensitive to moisture, with reagent 5 being considerably more sensitive than the rest. Derivatization of model compounds with these reagents is conveniently carried out in an NMR tube, using syringe techniques. The slightly exothermic reactions are generally completed within 15 min. Reagent Evaluation. For evaluating the effectiveness of a given reagent, several criteria must be considered (1) In order to be able to analyze for the presence of different functional group classes in a mixture as complex as a coal condensate, the reagent of choice should give 31PNMR chemical shifts with a minimum of peak overlap between chemical shift ranges of derivatized functional groups. In other words, derivatized phenols, for example, should ideally possess 31PNMR chemical shifts that fall outside the chemical shift range of derivatized alcohols, acids, etc. (2) In order to be able to achieve resolution of derivatives within a given functional group class, e.g., to identify individual phenols, a sufficiently large chemical shift range for each of the derivatized functional group classes should be observed. Should such a reagent not be found, it may be possible to use two or more complementary reagents. (3) The reagent and the derivatized products should be sufficiently stable to be manipulated without undue effort. (4) The derivatization reaction should give a single product for virtually any ratio of reagent to substrate. 31PNMR chemical shifts were recorded for several functional group classes derivatized with reagents 2-7. In an initial screening, the reagents were reacted with mixtures of phenols, alcohols, acids, and amines in order to establish the chemical shift ranges for each of these
Chlorophospholanes as 31PNMR Tagging Agents Table 11. 31PNMR Chemical Shifts (ppm) of Phenols Derivatized with 2" phenol o-cresol m-cresol p-cresol 2,3-dimethylphenol 2,4-dimethylphenol 2,5-dimethylphenol 2,6-dimethylphenol 3,4-dimethylphenol 3,5-dimethylphenol 2,3,5-trimethylphenol 2,3,6-trimethylphenol 2,4,64rimethylphenol 3,4,5-trimethylphenol p-ethylphenol o-isopropylphenol o-phenylphenol 4,4'-biphenol 5-indanol
5,6,7,84etrahydro-@naphthol a-naphthol @-naphthol 8-quinolinol catechol hydroquinone 2-methoxyphenol (guaiacol) 2-methoxy-6-methylphenol 3-methoxyphenol 2-methylresorcinol 3-ethylphenol
153.59 155.93 154.02 153.06 155.51 155.26 156.36 161.99 153.72 154.50 154.48 161.76 161.52 154.48 153.23 156.42 160.95 154.85 153.79 154.08 159.70 155.27 158.17 161.40 154.69 161.68 166.29 154.75 157.35 153.50
Energy &Fuels, Vol. 4, No. 2, 1990 199 Table 111. 3*PNMR Chemical Shifts (ppm) of Alcohols, Acids, Amines, and Thiols Derivatized with 2" Alcohols methanol benzyl alcohol isoamyl alcohol menthol tert-butyl alcohol cyclohexanol
145.98 145.11 143.41 151.78 145.66 147.17
Acids benzoic acid &mandelic acid 2,4,6-trimethoxybenzoic acid a-methylcinnamic acid
154.55 152.18 159.83 153.19
Amines 2,6-dimethylaniline o-toluidine diisopropylamine N-ethylaniline pyrazole
103.88 100.61 92.63 99.97 91.43
Thiols 2-propanethiol thiophenol o-thiocresol 3,4-dimethylthiophenol
102.16 113.43 112.31 112.94
"The chemical shift of the hydrolysis product of 2 (8) was used as the internal standard.
"The chemical shift of the hydrolysis product of 2 (8) was used as the internal standard.
functional group classes. The mixtures of model compounds3 representing each functional group were chosen such that they would provide a broad spectrum of compounds within that functional group class. The chemical shift ranges obtained are presented in Table I and are depicted in Figure 1. To obtain the 31PNMR shifts, a CDC13 solution of triethylamine and the reagent was reacted with one of the model compounds (a drop of liquid or a few crystals of solid). 31PNMR spectra were then recorded after successive additions of series of different model compounds until the reagent was almost exhausted. Reagents 2-7. Reagents 2 , 3 , and 4 are all members of the 1,3-dithiaphospholane class of compounds, with 3 and 4 possessing two methyl substituents in different stereochemical relationships. From the analogous 1,3-dioxaphospholane reagents, we learned that ring substituents such as methyl groups influence the observed chemical shift ranges of derivatized functional group c l a ~ s e s .In ~ order to determine whether a similar influence exists within the 1,3-dithiaphospholane series, reagents 2 , 3 , and 4 were evaluated. Unfortunately, the series could not be completed with the tetramethyl reagent (analogous to 1) because a synthetic route for this 1,3-dithiophospholane is not available. From Figure 1, it is seen that the chemical shift ranges of amines and thiols derivatized with 2 fall well outside the region observed for the derivatized -OH functional group classes (i.e., phenols, acids, and alcohols). Reagent 2 is the only one investigated so far for which derivatized -OH functional groups do not overlap their 31Pchemical shifts with those of any other heteratom functional group, thus making reagent 2 a good candidate for total -OH functional group analysis. Furthermore, the 31Pchemical shift regions of phenols and alcohols derivatized with 2 show almost no overlap. This is not true, however, for carboxylic acids and phenols derivatized with 2. The 31P data for the model compounds derivatized with 2 are recorded in Tables I1 and 111.
I
OH
I
I
160
159
I
I
157
I
1
156 155 "P Chemicol Shift (ppm)
158
154
I
1
153
152
Figure 2. 31PNMR spectrum of a mixture of phenols derivatized with reagent 2.
In Table IV are recorded substituent parameters for the
31P chemical shifts for compounds derivatized with 2. These parameters are comparable to or a t least 3 times larger than their counterparts wherein 1 is the derivatizing agent.3 All of the calculated 6(31P)values are within 0.3 ppm of the calculated values except for 2,3,5-Me3C6H20H (A[6(31P)] = 1.46 ppm) and for 3,4,5-Me3C6H20H(A[6(31P)] = 0.56 ppm). Such deviations were not observed for these compounds with 1, and the reason for their Occurrence with 2 is presently obscure. Owing to the substantial shift associated with a second o-Me group in phenols derivatized with 2 (Table IV), the 31PNMR chemical shifts fall into two separate regions, namely, 161.0-162.0 and 153.0-157.5 ppm (Table 11). In a future publication the advantageous resolution capabilities quantitatively analyzing individual phenols present in a coal pyrolysis will be demonstrated.12 The chemical shift range of 15.3 ppm observed for phenols derivatized with reagent 2 is the largest thus far observed for this functional group class, thus rendering this reagent an excellent candidate for the analysis of complex (12) Lensink, C.; Verkade, J. G. Manuscript in progress.
Lensink and Verkade
200 Energy & Fuels, Vol. 4, No. 2, 1990
Table IV. Substituent Parameters (ppm) for Calculations of rlP Chemicals Shifts (ppm) for Alkyl-Substituted Phenols Derivatized with Reagent 2 o-Me +2.34
m-Me
substituent parametersa p-Me o,m-Me
+0.43 +0.43 +0.43
+2.34 +2.34 +2.34
6(31P)
second o-Me
-0.85 +6.06 -0.53 -0.53 -0.53
+2.34 +0.43 +0.43 +0.43 +0.43
+2.34 +2.34 +2.34
-0.85 -0.85 -0.53 -0.53 -0.53
+0.43 +0.43
+6.06 +6.06
phenol group substituents 2-Me 3-Me 2,5-Me2 2,3-Mez 2,6-Me2 4-Me 2,4-Mez 3,4-Mez 3,5-Mez 2,3,5-Me3 2,3,6-Me3 2,4,6-Me3 3,4,5-Me3 5-hydroxyindan
calcd 155.93 154.02 156.36 155.51 161.99 153.06 155.40 153.49 154.45 155.94 161.57 161.46 153.92 153.49
obsvd 155.93 154.02 156.36 155.51 161.99 153.06 155.26 153.72 154.50 154.48 161.76 161.52 154.48 153.79
aBased on the 31Pchemical shift of 153.59 ppm for phenol derivatized with 2.
mixtures of phenols. This is illustrated in Figure 2, wherein is displayed a 31PNMR spectrum of 22 phenols, derivatized with reagent 2. It is seen that a high degree of resolution has been achieved with this reagent compared with reagents such as 1,3 making it possible to identify individual components. Reagent 2 can be very sensitive toward relatively small changes in the substituent on the phenol ring. For example, p-cresol and p-ethylphenol differ by only a CH, group in the substituent in the phenyl ring para position, which is six bonds away from the phosphorus nucleus. The chemical shift difference observed for these compounds derivatized with reagent 2, however, is a substantial 0.17 ppm. On the other hand, 3,5-dimethylphenol and, as noted above, 2,3,5-trimethylphenol and 3,4,5-trimethylphenol derivatized with 2 have identical 31Pchemical shifts. When reagent 2 is reacted with difunctional compounds such as 1,2-diols, transesterification apparently occurs, giving rise to two chemical shifts as illustrated in reaction 2. The position of one of the chemical shifts (214.8 ppm)
63'P: 214.8
108.8
in the product is close to those observed for thiols derivatized with 1,3-dio~aphospholanes.~The resonance at 108.8 ppm lies in the region associated with thiols derivatized with 2 (Figure 1 and Table 111). An interesting property of reagents of the phospholane class is the reaction of two molecules of reagent to react with one molecule of water to give an anhydride (e.g., reaction 3) when the ratio of reagent to water is high.3J3 Me
Me
Me
Me
Me
Me
1
The 31Pchemical shift a t 152.4 ppm observed when 2 is hydrolyzed under these conditions is assigned to the analogous hydrolysis product 8. Although 2 could conp '\s S
C P ' O '
1
8
ceivably be used for the quantitative analysis of trace (13) Reinartz, K.; Verkade, J. G. Manuscript in progress.
moisture contents in nonaqueous solutions, the chemical shift of 8 falls between the chemical shift ranges observed for phenols and alcohols derivatized with reagent 2. This result may be a complicating factor in the analysis of mixtures of phenolic and alcoholic -OH moieties when moisture is present. Reagent 4 reacts with model compounds in a manner more complicated than anticipated on the basis of products isomeric at phosphorus The evaluation of reagent 4 was therefore not pursued further. Screening of reagent 3 with mixtures of model compounds shows that derivatized phenols give 31PNMR signals in the 144.4-158.5 ppm region and that derivatized alcohols display signals in the 138.3-149.7 ppm region (Table I). The observed 31P chemical shift ranges for model compounds derivatized with reagent 3 are of the same magnitude as those observed for 2, but the former reagent displays more overlap between the alcohol and phenol regions. It can therefore be concluded that the introduction of methyl substituents in the 3- and 4-positions of the dithiaphospholane ring does not lead to an improvement in observed chemical shift ranges. Reagent 5 is very sensitive toward moisture and air. Although it reacts in the expected manner with phenols and carboxylic acids to give well-defined ranges of chemical shifts for these functional group classes, it reacts in a complex and presently poorly understood manner with alcohols, making it a less desirable candidate for the analysis of -OH functional groups. Moreover, the phenol region of 31Pchemical shifts fully overlaps the carboxylic region for this reagent. On the other hand, the observed chemical shift range of 61.0-78.2 ppm for amines derivatized with reagent 5 falls well outside the region observed for phenols or carboxylic acids. The signals observed for model compounds derivatized with reagent 6 are relatively broad compared with other reagents, probably owing to the presence of quadrupolar nitrogen nuclei near the NMR-active phosphorus atom. The chemical shift ranges of phenols, alcohols, and acids derivatized with 6 all overlap. Because of the broadening of the signals compared with other reagents and because of the chemical shift ranges observed are no better than for the other phospholanes, compound 6 is not considered to be a candidate derivatizing reagent. All the reagents screened so far are members of the phospholane series, in which the phosphorus atom is part of a five-membered ring. Until now, the major variation (14)See ref 3 for a more detailed discussion of this isomerism when the 1,3-dioxa analogue of 3 is employed.
Energy & Fuels 1990,4, 201-206 in the reagents tested is the type of ring heteroatom bonded to the phosphorus atom. In order to investigate whether a different ring size has a salutory effect on the observed chemical shift ranges, reagent 7 was evaluated. Reagent 7 is a 1,3-dithiaphosphorinane in which the phosphorus atom is part of a conformationally mobile six-membered ring. The observed 31Pchemical shift ranges for phenols and alcohols completely overlap, and moreover, they are not as large as was observed for reagent 2, for example. Furthermore, carboxylic acids derivatized with reagent 7 provide unstable products which decompose rapidly to a complex mixture of products. The increased
20 1
ring size in 7 does not, therefore, appear to enhance the effectiveness of this reagent.
Acknowledgment. Ames Laboratory is operated for the U S . Department of Energy by Iowa State University under Contract No. W-7405-ENG-82. This work was supported, in part, by the Assistant Secretary for Fossil Energy through the Pittsburgh Energy Technology Center. Partial support through DOE Grant No. DE-FG2288PC88923 is also acknowledged. Registry No. 1, 14812-59-0; 2, 4669-51-6; 5, 30148-56-2; 6, 6069-36-9; 7, 28896-84-6.
Tritium as a Tracer in Coal Liquefaction. 3. Reactions of Morwell Brown Coal with Tritiated Hydrogen Molecules Toshiaki Kabe,* Kenichi Kimura, Hideo Kameyama, Atsushi Ishihara, and Kyoko Yamamoto Department of Chemical Engineering, Tokyo University of Agriculture and Technology, Nakamachi, Koganei-shi, Tokyo 184, Japan Received September 22, 1989. Revised Manuscript Received January 29, 1990
The liquefaction of Morwell brown coal was carried out with tritium-labeled gaseous hydrogen. The effects of Ni-Mo-Alz03 catalyst, reaction time, and temperature on the hydrogen transfer were studied. The relationships between liquefaction conversions and hydrogen-tritium transfers were investigated. Morwell brown coal was easily liquefied at 350 "C, and the conversion reached ca. 100% at 400 "C even without catalyst. The liquefaction proceeded by the hydrogen donation from solvent to coal. Ni-Mo-Alz03 was not so useful for the coal conversion but was effective for the cracking of the coal liquids. Furthermore, the catalyst promoted hydrogen exchange between the gas phase and the coal. At the initial stage of the reaction, tritium concentrations in heavy components were higher than those in light components, in both the presence and absence of the catalyst, which was reversed a t the final stage.
Introduction In order to develop a practical process for coal liquefaction, it is important to elucidate the mechanisms of coal liquefaction. The estimation of the mobility of hydrogen in coal gives a key to solve them. Since the pioneering study of deuterium under magnetic resonance spectroscopy (2H NMR) by Schweighardt et al.,I a number of attempts have been made to elucidate the mechanisms of coal liquefaction by using deuterium tracer and NMR or MS methods.z-12 However, because of the lack of quantitative (1)Schweighardt, F. K.; Bockrath, B. C.; Friedel, R. A.; Retkofsky, H. L.Anal. Chem. 1976,48, 1254. (2)Heredy, L.A.; Scowronski, R. P.; Ratto, J. J.; Golberg, I. B. Prepr. Pap.-Am. Chem. Soc., Diu. Fuel Chem. 1981,26, 114. (3) Ratto, J. J.; Heredy, L. A.; Skowronski, R. P. Prepr. Pap.-Am. Chem. SOC.,Diu. Fuel Chem. 1979,24, 154. (4)Franz, J. A. Fuel 1979, 58, 405. (5) Franz, J. A.; Camaioni, D. M. Prepr. Pap.-Am. Chem. Soc., Diu. Fuel Chem. 1981,26, 106. (6)Cronauer, D.C.; Mcneil, R. I.; Young, D. C.;Ruberto, R. G. Fuel 1982, 61, 610. (7) Brower, K. P. J. Org. Chem. 1982, 47, 1889.
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data from 2H NMR, there are very few examples that enable the quantitative analysis of hydrogen transfer in coal liquefaction. We reported that the tritium and 14C tracer techniques were effective tracing the reaction pathways of hydrogen atoms in Taiheiyo, Wandoan, and Datong coal liquefaction and gave quantitative information related to hydrogen transfer in the subbituminous and bituminous coal^.'^-'^ (8) Wilson, M. A,; Collin, P. 4.; Barron, P. F.; Vassalo, A. M. Fuel Process. Technol. 1982,5, 281. (9) Wilson, M. A,; Vassalo, A. M.; Collin, P. J. Fuel Process. Technol. 1984, 8,213. (10) Skowronski. R. P.:Ratto. J. J.: Goldbera. - I. B.; Heredv, L. A. &el 1984, 63, 440. (11) Maekawa, Y.; Nakata, Y.; Ueda, S.; Yoshida, T.; Yoshida, Y. In Coal Liauefaction Fundamentals: Whitehurst. D. D.. Ed.: ACS SWIIDOsium Shies 139; American Chemical Society: Washington, DC, f986; p 315. (12)King, H.H.;Stock, L. M. Fuel 1982, 61, 129. (13) Kabe, T.;Nitoh, 0.; Kim, S. J. J p n . Pet. Inst. 1983, 26, 424. (14)Kabe, T.;Nitoh, 0.;Kawakami, A.; Okuyama, S.; Yamamoto, K. Fuel 1989,68,178. (15) Kabe, T.; Nitoh, 0.; Funatsu, E.; Yamamoto, K. Fuel Process. Technol. 1986,14, 91.
0 1990 American Chemical Society
