Ind. Eng. Chem. Prod. Res. Dev. 1983, 22, 250-255
250
Nomenclature
L i t e r a t u r e Cited
S = weight fraction sulfur remaining t = reciprocal of weight hourly space velocity, g/(h g of catalyst) A = catalyst activity k = apparent rate constant K = adsorption constant P = partial pressure, psi
Albert, D. K. Anal. Chem. 1078, 5 0 , 1822. Benesi, H. A. J. Catal. 1073, 2 8 , 176. Bertolacini, R. J.; Sue-A-Quan, T. A. US. Patent 4 140 626, 1979. Brown, H. C.; Gintls, D.; Domask, L. J. Am. Chem. SOC. 1056, 78, 5387. Drushel, H. V. Anal. Chem. 1077, 4 9 , 932. Kirsch, F. W.;Shallt, H.; Heinemann, H. Ind. Eng. Chem. 1050, 57, 1379. Meisel, S. L.; Koft, E.;Ciapetta. F. G. Am. Chem. SOC., Div. Pet. Chem., Prepr. 1957, 2(4), A45. Mllls, G. A.; Boedeker, E. R.: Oblad, A. G. J. Am. Chem. SOC. 1050, 72,
Subscripts A = ammonia B = nitrogen in base feed
Oswald,.A. A.; Noel, F. J. Chem. Eng. Data 1061, 6 , 294. Plank, C. J.; Nace, D. M. Ind. Eng. Chem. 1055, 4 7 , 2374. Satterfleld, C. N.; Modell, M.; Mayer, J. F. AIChE J . 1975, 27, 1100. Viland, C. K. Am. Chem. SOC.,Div. Pet. Chem., Prepr. 1957, 2(4), A41.
C = added nitrogen compound Registry No. Cobalt, 7440-48-4; molybdenum, 7439-98-7; 2,5-dimethylpyrrole,625-84-3; 4-methylaniline, 106-49-0;benzylamine, 100-46-9;Cethylpyridine, 536-75-4; 3,5-dimethylpyridine, 591-22-0;2,4-dimethylpyridine, 108-47-4;2,6-dimethylpyridine, 108-48-5;2,4,6-trimethylpyridine,108-75-8.
1554.
Received for review September 9, 1982 Accepted January 24, 1983 Presented before the Seventh North American Meeting of the Catalysis Society, Boston, MA, Oct 1981.
Comparison of Hydrodesulfurization and Hydrodenitrogenation over API Reference Clays, Silica, Alumina, and Cobalt Molybdate Yusaka Sakatat and Charles E. Hamrln, Jr.' Department of Chemlcei Engineering and Institute for Mlnlng and Mlnerals Research, University of Kentucky, Lexlngton, Kentucky 40506
A pulse reactor at 723 K and 239 kPa was used to study the catalytic activity and selectivity of several clays found in coal mineral matter. Of these, montmorillonite 22a gave the maximum thiophene conversion of 13% while kaolinite 5 produced the maximum conversion of 33% for n-butylamine. The latter value was higher than that found for silica (7%), cobalt molybdate (20%), or alumina (29%). The clay activity of HDS was correlated with the impurity iron content (correlation coefficient, R = 0.995) and the surface area (R = 0.91). For HDN the AVSi ratio gave the best correlation with R = 0.87, while the titanium content was marginally significant. I t was found that even under a hydrogen atmosphere the six clays tested gave primarily butenes from thiophene, pyrrolidine, and n -butylamine.
Heteroatom (S,N,O) removal is one of the prime goals of coal liquefaction processes. Dissolution of the coal takes place at elevated temperatures and pressures in the presence of hydrogen and a solvent. In all current processes under investigation the feed coal contains inherent mineral matter. For 65 Illinois Basin coals more than 50% of the mineral matter consists of clays such as kaolinite, illite, and illitemontmorillonite (Rao and Gluskoter, 1973). In another study of 57 U.S. coals O'Gorman and Walker (1972) found kaolinite in all of them at a median value of 30% of the mineral matter. The purpose of this study was to carry out HDS and HDN of several compounds over clays which constitute a significant portion of mineral matter. It was not deemed feasible to separate the clays from coal mineral matter so six samples of the API reference clays (API, 1951) were chosen: kaolinite 5 and 9, illite 35 and 36, and montmorillonite 22a and 27. Methods Catalyst Treatment and Characterization. Chemical analyses of the six clays chosen for study were reported in API project 49 and are reported in Table I. Complete t Department of Synthetic Chemistry, Okayama University, Okayama, 700 Japan.
0198-4321/83/1222-0250$01.50/0
Table I. Chemical Analysis of Clay Minerals (API 49,1951)' montkaolinite morillonite illite no. 5 no. 9b no. 22a no. 27 no. 35 no. 36 SiO, 45.58 45.98 51.52 58.53 56.91 57.41 A1,0, 37.62 37.61 17.15 19.61 18.50 17.96 4.99 3.10 4.99 1.00 0.63 5.65 Fe,O, FeO 0.13 0.13 0.32 0.13 0.26 0.26 0.01 2.65 2.07 2.25 2.80 MgO 0.03 0.25 0.35 1.72 1.59 0.64 CaO 0.32 0.32 0.15 Na,O 0.42 0.15 1.68 0.43 0.85 0.31 5.10 5.75 0.49 0.44 K,O 6.21 5.98 6.70 H,O+ 13.42 13.46 8.55 7.89 2.86 2.97 H,O0.63 0.46 11.22 TiO, 1.42 0.50 0.48 0.12 0.81 0.82 a H,O' is water lost above 383 K. H,O- is water lost at 383 K.
geological identification and other physical and chemical properties are also reported therein. Samples were crushed with a mortar and pestle and sieved to 24/42 mesh (average particle size, 0.533 mm). They were then treated at 723 K for 15 h in flowing helium (2.5 mL/s (STP)) to prevent changing of their physicochemical character by decomposition while testing for catalytic activity. In ad0 1983 American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 22, No. 2, 1983 251 Table 11. Weight Changes of Clays b y Heat Treatment and Sulfidation and Packing Densities of Catalysts ~~
fractional weight changea decom- sulfiposition, dation, sample
%
%
kaolinite no. 5
-13.31
-0.49
kaolinite no. 9 montmorillonite no. 22a montmorillonite no, 27 illite no. 35 illite no. 36 SiO, A1203 CoMo/Al,O,
-12.23 -14.31 -12.32 -3.99 -8.78
-0.32 +0.01 -0.31 -0.57 +1.27
aPP packing density, kg/m3 0.77 X 103 1.20 0.95 1.08 1.22 1.13 0.52 0.78 0.92
Positive value means weight increase; negative, weight loss.
dition, the heat-treated samples were presulfided with a 1% H2S-He mixture at 723 K for 3 h prior to testing. Kaolinite and montmorillonite lost from 12.2 to 14.3 wt 90, but illite lost only 4.0 to 8.8% as a result of the heat treatment. Appreciable weight changes were not detected by sflidation except for illite 36 which gained 1.3% based on the decomposed sample weight. These data are summarized in Table I1 for the clays. Also given are the apparent packing densities of the clays and some reference catalysts. The reference catalysts were SiOz (-325 mesh, 99.9%), Alz03(1/8-in.cylinders, Harshaw Chemical A1-104T) and cobalt molybdate (l/,4n. cylinders, Harshaw CoMo-402T). The silica was die-pressed under 331 MN/m2 for 2 min, crushed, and sieved to 24/42 mesh. The pellets were also crushed and sieved to this size before use. X-ray Fluorescence (XRF) Analysis. To allow comparison of the clays based on their chemical constituents, XRF analyses were carried out at low energy for elements for atomic numbers 12 (Mg) to 26 (Fe) and at high energy for elements from 26 to 42 (Mo). Data were obtained on a Finnigan Model 900 spectrometer operated at 14 kV and 0.4 mA, under 0.133 kPa vacuum with a 3-mm collimator but without a filter for the low-energy values. For high energy the conditions were 40 kV and 0.80 mA, atmospheric pressure, a 3-mm collimator, and Rh filter. In both cases the sample counting time was lo00 s and the values reported in Table I11 are averages of five determinations. Values are reported for the raw, decomposed, and sulfided clays. Elements which were not detected in any of the samples included Mg, P, Ge, Se, and Br. It is noted that no sulfur was detected in any of the kaolinite samples: raw, decomposed, or sulfided. Montmorillonite 22a and the two illites increased in sulfur content upon H2Streatment, and illite 36 is seen to have the highest sulfur content. A least-squares fit of the chemical analysis data in Table I w. the XRF data in Table 111gave the followingR values: A1203-Al, 0.997; Si02-Si, 0.922; K20-K, 0.978; CaO-Ca, 0.427; TiOz-Ti, 0.944; and (Fe203+ Fe0)-Fe, 0.949. Except for the calcium value, the correlation coefficients R are very good and XRF data are used as indicators of the element contents of the clays. X-ray Diffraction (XRD) Analysis. To determine any crystalline changes of the raw clay upon heat treatment and H2S treatment at 723 K, X-ray diffraction patterns were examined. A General Electric Model XRD-5 instrument was used under the following conditions: Cu Ka, Ni filter, 50 kV, 15 mA, 200 counts/s, time constant = 4 s, and scanning speed = 2O(28)/min. Samples were
28, Degrees
Figure 1. X-ray diffraction patterns of kaolinites and changes after heat treatment and H2S treatment. IO
20
l l ' ' 1 I l
30
I " '
40
50
60
IM
z e . Degrees
Figure 2. X-ray diffraction patterns of montmorillonites and illites after heat treatment.
spread in a thin layer on two-sided adhesive tape which was attached to a glass slide. In this way no dissolution or other effect from water was introduced. The tape (Nichiban Co., Japan, Cat. No. 430) also did not contribute any peaks. The XRD results are shown in Figures 1to 3. A drastic change by heat treatment was observed only for kaolinite which is indicated in Figure 1. The bottom pattern is for kaolinite 9 showing many sharp peaks designated by K with the major peak designated by K*. Quartz (Q) is also apparent as an impurity. The curve immediately above shows the absence of the sharp K peaks and only a few quartz peaks remaining. This structural change of kaolinite to metakaolinite was reported by Mitchell and Gluskoter (1976) for coal mineral matter containing this
Ind. Eng. Chem. Prod. Res. Dev., Vol. 22, No. 2, 1983
252
33
20
IO
1
'
' ' / \ M I
1
1
MI
50
40
"
'
' IC
-
I
COIC l e
60 62
,
S10,
&O, CoMo/AI1O,
0
5
10
15
Tot01 Conrerr8on l o
25
20
30
35
95
)O
C, Comwnentr , Y.
Figure 5. Comparison of total conversion to C4 Components.
1
1
1
I 10
20
30
50
40
60 62
2 8 . Degrees
Figure 3. X-ray diffraction p a t t e r s of decomposed montmorillonites and illites after H2S treatment. VenI 3
Venl I
t
t Pulse Inlet
Controllers
He
Hewlell- Pockord 5830 Gas Chromologroph
Tonk
H.S
Tonk
H,
Tonk Temperature Controller Thermocouple
Figure 4. Flow diagram of pulse reactor system.
clay and by Ryland et al. (1960). The same is true for the sulfided clay. For kaolinite 5 the decomposed clay shows impurity peaks for chlorite (CH) which is (Mg,A1,Fe)lz(Si,A1)8020(OH)16 and quartz with the former persisting after sulfidation. The chemical analysis in Table I shows a low concentration of magnesium suggesting this element has been ion-exchanged. In Figure 2 the heat-treated samples of montmorillonite show peak shifts to 8.8' (d = 0.1 mm) from 6.8O for no. 22a and 7.6O for no. 27 for the raw clays. This shift was also reported by O'Gorman and Walker (1972). Characteristic peaks for illite (I) did not shift upon heat treatment. Quartz was present in all the samples, but pyrite was found only in the illites. Sulfided samples of the montmorillonite and illite clays indicate the presence of pyrite, but the major effect is seen for illite 36 a t 33O indicating the weight change in Table I1 and the XRF increase in sulfur are due to pyrite formation from the iron oxides present. Surface Area Measurement. Surface areas of the clays after testing were measured by low-temperature nitrogen adsorption at five pressures with a Micromeritics Digisorb 2500. Samples were outgassed a t 523 K under vacuum (10" torr or less) for 4 h prior to adsorption. Experimental System and Procedure A flow diagram of the experimental system used for decomposition, sulfidation, and catalytic activity testing is shown in Figure 4. For decomposition and sulfidation a quartz reactor (10 mm i.d. X 0.92 m long) was loaded with a 2.5 X kg sample on quartz wool and gas passed down through the bed and vented a t vent 2. For the pulse studies a SS reactor tube (0.89 mm i.d. X 65 mm long) was
charged with 500 mg of sulfided clay and maintained at 723 K and 239 kPa. Hydrogen (UHP, Matheson, 99.999 ~ 0 1 %was ) passed through the reactor at 1.167 m L / s , and a 0.5 mL/s flow through the reference side of the gas chromatograph (Hewlett-Packard Model 5830A). Separation of the products which included n-butane, l-butene, trans-2-butene, cis-2-butene, and 1,3-butadiene was accomplished with a SS column (6.35 mm i.d. X 7.32 m long) of 20% bis-2-methoxy ethyl adipate on 60180 mesh Chromasorb W. Column temperature was maintained at 308 K to give good resolution. Total conversion was calculated from the amount of the C4 gases produced and selectivity for each C4 product was also determined. Thermal cracking of the reactants was not important below 748 K in the empty reactor. Reagent grade thiophene, pyrrole, pyrrolidine, and n-butylamine were obtained from Aldrich Chemical Co. and were used without purification. Normal sequence of pulsing was in the order above to assure that the HDN reaction took place on a sulfided (H2S adsorbed-thiophene pulsed) surface. Results reported represent averages for three to five pulses. The reference catalysts were pretreated with a 6.32% H2S-Hz mixture a t 723 K for 3 h at atmospheric pressure. The gas flow rate was 1.167 mL/s (STP). Weight losses were determined after each activity test and amounted to less than 3% for all the clays, but 5% for the SiOz and 6% for the cobalt molybdate catalyst. All comparisons are made based on the initial catalyst weight. Results Total Conversion. Conversions of thiophene, pyrrole, pyrrolidine, and n-butylamine to total C4 components at 723 K are shown in Figure 5 for the clays and the reference catalysts. As expected, the CoMo/A1203catalyst which has been used in commercial hydrodesulfurizationand coal liquefaction processes shows a high conversion of 97% for thiophene. It is less impressive for HDN where tha maximum conversion was 20% for n-butylamine. Pure Alz03exhibits opposite behavior: about 1% conversion for HDS, but for pyrrole, pyrrolidine, and n-butylamine HDN, good activity yielding 22-29% conversion. Pure SiO, catalyst shows the poorest activity for HDS and HDN of the three reference catalysts. Both kaolinite clays give good conversion for n-butylamine (17-33%) comparable with pure A1203but almost no activity for HDS. Montmorillonite and illite clays give 5-13% conversion for HDS and n-butylamine HDN under the test conditions employed. HDN conversions are in following order, except for AZO3 C-C-C-C-NH?
>>
pp H
(1)
H
This order has also been found for the same reaction conditions using coal mineral matter as catalyst (Sakata and Hamrin, 1983).
Ind. Eng. Chem. Prod. Res. Dev., Vol. 22, No. 2, 1983 253 l
l
c-c-c-.:
I
l
/
c- c-c- c
0 K a o l ~ n < t# e 5 0 Kaolinite # 9 V Monl # 22 o A Monf # 27
c;c-L'-;
c-c:c'-c
c =c- c-c
0 I l l l t e #35 0 I l l l t e # 36
C-,C=C-C
c-/c=c-c C-/c=c\-C
c = c -c = c
0 CoMo/Al,O, 0
10
20
30
40
Selectiwty of C,
60
50
70
80
90
I
Components , %
c=c-c=c
Figure 6. Selectivity of C, components produced by n-butylamine HDN with clays.
I
I
I
I
I
1
0
IO
20
30
40
50
Selectivity
,%
Figure 9. Comparison of selectivity for HDS with reference catalysts.
1
I 0
10
I
I
I
20
30
40
60
50
S e l e c t ~ w t y, %
Figure 7. Comparison of selectivity for HDS and HDN with montmorillonite no. 22a. l
0
IC
20
40
30 Selectivity,
50
,
I
60
70
YO
Figure 8. Comparison of selectivity for HDS and HDN with illite no. 36.
Selectivity of Clay Catalysts. Selectivities for n-butane, 1-butene, trans-2-buteneYcis-2-butene, and 1,3-butadiene calculated for n-butylamine HDN are shown in Figure 6 for the clay catalysts. Selectivity is defined as % conversion to a given compound divided by the total conversion to C4 compounds. Both kaolinites, montmorillonites, and illites give similar product distributions (Figure 6). Butane and 1,3-butadiene concentrations are very low, and the selectivity order of the three butenes is as follows kaolinite: C-C-C-C > cis-butene > trans-butene (2) montmorillonite: cis-butene, trans-butene> C=C-C-C (3) >> trans-butene > cis-butene (4) illite: C=C-C-C It is surprising that the hydrogen-saturated n-butylamine pulse always gives these partially dehydrogenated butenes as major products even in a hydrogen-carrier gas flow. These selectivity patterns are kept for other HDN and HDS reactions. Figures 7 and 8 give examples for comparison of product distributions for thiophene HDS and pyrrolidine and n-butylamine HDN reactions catalyzed by montmorillonite 22a and illite 36, respectively. It is very interesting that an unsaturated five-membered sulfur compound (thiophene), a saturated five-membered nitrogen compound (pyrrolidine), and a saturated chain amine produce butenes mainly and show a similar distribution of products in spite of the big differences in total conversion. Selectivity of Reference Catalysts. Figures 9 and 10 show the product distributions for thiophene HDS and n-butylamine HDN reactions catalyzed by pure SO2,gure A1203 and CoMo/A1203 catalysts. For these materials
Figure 10. Comparison of selectivity for n-butylamine HDN with reference catalysts.
similarity of product distribution for HDS and HDN reactions is less than that of the clays. For the n-butylamine HDN reaction, Figure 10 is comparable with Figure 6. CoMo/A1203catalyzes this reaction to produce n-butane and NH3 almost completely (selectivity to n-butane is 88%) but both the pure Si02 and A1203catalysts give about 95% selectivity to unsaturated butenes and butadiene. A1203gives cis-2-butene as the major product, whereas Si02 gives 1-butene predominantly and the selectivity pattern is very close to that of illite. Butenes were also found to be the sole products of deamination of 1-and 2-aminobutane over aluminum oxide at 547 K and porous glass at 532 K by Lycourghiotis et al. (1979). Discussion Reaction Scheme. Previous investigators (Owens and Amberg, 1961; Rollman, 1977) report the path in eq 5 for
-
c=c-c-c C=C-C=C
t H2S
4
C-C=C-C
c-c=c-c c-c-c-c
4
(5)
thiophene HDS which indicates desulfurization does not require ring saturation. Cocchetto and Satterfield (1976) proposed the reaction scheme in eq 6 for pyrrole HDN
. H
H
(6)
based on the experimental work of Smith (1957). The steps are ring saturation (I), ring opening by C-N cleavage (II), and denitrogenation (111). The results of this work shown in Figure 5 and eq 1 indicate the relative ease of nitrogen removal from n-butylamine compared to that for the ring compounds. In addition to the above studies total conversion of HDS and HDN for many model compounds have been reported experimentally (Qader et al., 1968; Namba et al., 1970; McIlvried, 1971; Satterfield et al., 1975; Sattefield and Cocchetto, 1975),but few papers (Bevgeling et al., 1971; Sonnemans and Mars, 1974) have reported the distribution of the product hydrocarbons as shown in eq 5 and 6. CoMo/A1203 catalyst showed good hydrogenation character even at the low pressure of 239 kPa (20 psig) resulting in good selectivity to saturated n-butane for unsaturated thiophene and pyrrole reactions (total con-
254
Ind. Eng. Chem. Prod. Res. Dev., Vol. 22, No. 2, 1983
Table I11 kaolinite element
statea
no. 5
montmorillonite no. 9
no. 22a
no. 27
illite no. 35
no. 36
1.4 1.4 1.3 9.6 9.8 9.6 1.0 0.5 1.0 0.9 1.0 0.9 0 0 0 4.9 5.6 6.5 0.8 0.9 0.8 0.5 0.5 0.5 0 0 0 33.6 34.9 33.4
1.5 1.4 1.3 10.0 8.8 8.8 0 0 1.1 0.7 0.6 0.5 11.0 10.6 10.2 5.4 5.2 4.7 3.6 3.4 3.3 0.2 0.3 0.3 0.3 0.2 0.1 41.0 40.0 39.1
1.4 1.3 1.3 10.4 9.1 9.4 0.9 1.0 2.5 0.6 0.6 0.3 9.0 9.0 8.4 1.7 1.7 0.9 2.9 3.0 2.8 0.6 0.6 0.5 0 0 0 50.9 57.2 51.9
Energy) 66.7 70.9 68.0 0 0 0 0 0 0 0.9 1.7 1.7 0.2 0.3 0.3 0.8 0.7 0.8 0 0 0 17.1 19.8 32.4 10.0 8.3 10.8 0 0 0
81.8 82.6 80.7 0 0 0 0.7 0.5 0.5 0.6 1.2 1.3 0 0 0 0.8 0.5 0.4 6.7 6.0 5.5 2.4 1.9 1.9 5.8 4.7 3.9 0 0
122.3 126.8 114.9 0.5 0.7 0.7 0.5 0.4 0.4 1.4 2.1 2.2 0 0 0 0.9 0.8 0.8 5.2 4.6 4.1 11.4 7.1 9.6 5.3 4.5 4.4 5.8 5.0 4.7
A. Results of XRF Analysis for Clay Catalysts (Low Energy) Ai
R D S
Si
R
D S S
c1 K
R D S R
D S R D S
Ca
R
Ti
D S R D S
Cr
R
Mn
D S R D S
Fe
R
D S Fe Ni cu Zn Ga AslPb
Rb Sr
Zr
Mo
R D S R
D S R D S R D S R D S R D S R D S R D S R D S R D S
2.8 3.0 2.9 6.9 6.7 6.8 0 0 0 1.0 0.6 0.6 0 0 0 0 0 0 6.7 6.9 6.8 0.8 0.4 0.4 0 0 0 4.0 4.5 4.4
2.8 2.9 2.9 7.6 7.0 7.3 0 0 0 1.1 0.6 0.6 0 0 0 0 0 0 2.5 2.2 2.2 0.6 0.2 0.2 0 0 0 7.4 7.3 7.5
1.2 1.3 1.2 9.5 8.9 9.3 0.4 0.1 1.6 1.0 1.0 0.8 1.0 1.0 1.5 2.4 2.5 1.8 3.4 3.4 3.2 0.5 0.5 0.3 0.8 0.8 0.9 73.9 74.4 72.0
B. XRF Analyses for Clay Catalysts (High 7.1 13.2 155.2 7.5 13.7 160.0 7.3 13.6 152.6 0.2 0 0 0.4 0 0 0.4 0 0 0.3 0 0 0.3 0 0 0.3 0 0 0.1 0 1.1 0.9 0.9 1.9 1.0 0.9 1.2 0.5 0.5 0 0.5 0.7 0 0.6 0.6 0 0.6 0.6 0.5 0.5 0.5 0.4 0.5 0.5 0.5 0 0 1.4 0 0 1.1 0 0 1.2 1.8 1.0 4.2 1.5 0.8 3.2 1.9 1.0 3.1 7.8 32.5 35.9 5.5 24.7 23.1 6.9 23.5 23.7 0 0 0 0 0 0 0 0 0
0
R = raw; D = decomposed in He; S = sulfided. Mg, P, Ge, Se, Br were not detected in 6 clays.
version to C4 components, 98.5% and 4.5%;selectivity to n-butane 37% and loo%, respectively) and saturated pyrrolidine and n-butylamine reaction (total conversion to C4s,6.7% and 19.9%; selectivity to n-butane, 100%and 87.8%).
Correlation of HDS and HDN With Clay Properties. As shown in Tables I and 111, the reference clay
samples contain many elements as impurities, which may act as catalysts for specified reactions. A least-squares fit of total conversions for thiophene HDS and n-butylamine HDN against relative intensity of XRF spectra for each element determined was carried out. Results are given in Table IV of the correlation coefficient R and the slope and intercept. Any element with a negative value of the slope
Ind. Eng. Chem. Prod. Res. Dev., Vol. 22, No. 2, 1983 255 Table IV. Results of Least-Squares Fit of Total Conversion vs. Element Concentration from XRF Data thiophene HDS element
coeff.
const.
A1 Si Al/Si K Ca Ti Cr Fe
-5.35 3.53 -31.2 0.475 0.37 7 -0.882 16.1 0.198
15.4 -24.4 12.9 4.20 4.91 8.32 0.00744 -1.07
Fe Ni cu Zn Ga Rb Sr Zr
0.0909 0.706 6.01 -0.434 -20.4 0.999 0.0225 0.0302
a-butylamine HDN R Low Energy 0.857 0.814 0.846 0.431 0.198 0.380 0.384 0.994
High Energy 0.997 0.031 0.279 0.058 0.854 0.451 0.05 3 0.054
-0.828 5.58 4.03 6.32 12.7 3.90 5.60 5.42
coeff.
const.
R
10.3 -7.26 62.9 -1.45 -2.11 3.53 -15.2 -0.268
-4.33 76.2 -0.0343 19.1 19.2 4.10 19.7 23.5
0.842 0.852 0.869 0.673 0.566 0.776 0.185 0.688
-0.122 1.30 --34.8 -4.76 37.8 -2.95 -0.220 0.135
23.1 13.8 24.4 20.1 1.36 19.8 16.1 12.6
0.686 0.029 0.408 0.325 0.808 0.679 0.265 0.123
could result in the creation of active catalytic surfaces. Further work is necessary to establish the ranges over which the impurity levels of iron are responsible for HDS activity and the Al/Si ratio and titanium content are responsible for the HDN activity of the six clays. In addition, the relation between the chemical form of these elements and activity needs to be clarified. Acknowledgment Appreciation is expressed to R. I. Barnhisel for helpful discussions and use of his XRD facilities, to W. G. Lloyd and T. V. Rebagay for analytical work, and to K. Weaver and A. H. Johannes for experimental help. Prepared for the U S . Energy Research and Development Administration under Contract No. EX-76-C-01-2233. This support is gratefully acknowledged. Registry No. A1,0,, 1344-28-1; CoMoO,, 13762-14-6; SiO,,
1
:g#9
0‘ 0
I
IO
Fe Relotive
7631-86-9; Kaolinite, 1318-74-7; illite, 12173-60-3; montmorillonite, 1318-93-0; thiophene, 110-02-1; n-butylamine, 109-73-9;pyrrolidine, 123-75-1; pyrrole, 109-97-7; nitrogen, 7727-37-9. “ 20 30
I
40
’
50
60
’
70
80
1
90
intensity of X - Ray Fluorescence AnolysIs
Literature Cited
100
[ counts/s
I
Figure 11. Total conversion of thiophene vs. Fe intensity by XRF.
and a large value of the intercept was eliminated. By this analysis, iron is revealed as the most favorable element in the clays for thiophene HDS (Figure 11). The iron content as the best predictor of thiophene HDS activity agrees with our previous results on the catalytic activity of mineral matter from western Kentucky coals (Sakata and Hamrin, 1983). For n-butylamine HDN, A1 showed the best correlation, but the relative intensity Al/Si gave a slightly higher R value. Titanium was found to be just below the 95% confidence level for HDN. These correlations are based on the assumption that conversion (catalytic activity) is proportional to the concentration of the effective element. HDS also correlated significantly at the 95% confidence level ( R = 0.909) with the clay surface area measured after testing. No significant correlation was found between HDN and surface area, but one was found between HDN and HzO+(water loss above 383 K). It is believed this loss
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Received for review July 9, 1982 Accepted January 12, 1983
