SiO2MoO3) catalysts

Hydrocracking of Athabasca bitumen binary metal oxide (SiO,-Moo, and CoO/SiO,-Moo,) catalysts Refa

ii.

K&eoglu,

Zbigniew

Jablonski

and

Colin

Department of Chemical Engineering and Applied Chemistry, Toronto, Ontario M5S lA4, Canada (Received 4 March 7986; revised 29 December 7986)

over

R. Phillips University

of Toronto,

The hydrocracking of Athabasca bitumen was studied over SiOzPMoO, (80:20 wt T”,), 2.92 and 5.54 wt % Co0 on SiOzPMoO,, and commercially available COO-MoO,/Al,O, catalysts at temperatures in the range 648-698 K for 2 h under an initial hydrogen pressure of 7.0 MPa in a batch reactor. The reaction products were separated into coke, asphaltenes, resins, aromatics, saturates and gases. The severity of cracking increased with increased reaction temperature. At 698 K, asphaltene and resin yields were low (0.59 and 13.22 wt %, respectively) and gas yields high (40.5 wt %). SiOzPMoO, and CoO/SiO,-Moo, catalysts showed higher activity than commercial CoOPMoO,/A1,O, catalyst in the conversion of heavy fractions (asphaltenes and resins) and in the formation of iight fractions (saturates and aromatics). (Keywords: bitumen; bydrocracking; catalysis)

oil sands deposit of Canada is of major economic significance. Bitumen from this deposit is, however, low in hydrogen and requires extensive upgrading by means such as cracking and hydrocracking. In the thermal and catalytic hydrocracking of Athabasca bitumen over COO-MoO,/Al,O, catalyst, Parsons and co-workers’ found that the amount of residuum remaining in the products was essentially the same for both thermal and catalytic hydrocracking. The removal of sulphur from the bitumen in thermal and catalytic reactions was found to be 25 and 73-75x, respectively, under optimal conditions. Herrmann et cd2 investigated the catalysts Fe on black carbon, Fe on lignite, iron oxide residue, zinc chloride on iron oxide, pure zinc chloride and COO-MoO,/Al,O, in the hydrocracking of bitumen. Of the catalysts examined, Fe on lignite was found to result in the highest conversion of residuum, the lightest liquid products and the highest gasoline yield. COO-Mo03/A120, catalyst was found to be the most efficient in sulphur removal. Ternan and Parsons3 investigated the hydrocracking of Athabasca bitumen using COO-MoO,/Al,O, on coal as catalyst. The liquid products obtained were low in sulphur (1.8 wt %), Conradson carbon residue (CCR) (2.0 wt %), total metal (Fe, Ni and V, 40 ppm) and pitch (2.5 wt %). Speight and Moschopedis4 hydrocracked Athabasca bitumen to produce liquids of low sulphur content in both the presence and the absence of COO-MoO,/Al,O, catalyst. The sulphur content of the liquid products decreased by 4.95-2.5 % in the presence of a catalyst. Little change in the sulphur content was observed in the absence of a catalyst. A hydrocracking process which uses an additive of pulverized coal impregnated with iron sulphate is the basis for Petro-Canada’s 5 Mbpd demonstration unit’. The system is expected to provide yields of distillates close to 100 ~01% and 90.5 ~01% conversion of the > 797 K The Athabasca

001&2361/87/060735-06$3.00 0 1987 Butterworth & Co. (Publishers) Ltd.

(> 524°C) fraction. The liquid products are expected to contain < 5 ppm total metals in the heaviest fraction and a total sulphur content of 1.8 y0 (reduced from the original 5.2%). The pulverized coal additive results in high residuum conversion, although still less than the commercial COO-MoO,/Al,O, hydrotreating catalyst. The development of new catalyst systems that have higher cracking and hydrogenating activities than commercially available catalysts is desirable in order to process heavy feedstock more efficiently. In the present work, SiO,-Moo, (80:20 wt %) and 2.82 and 5.54 wt % Co0 on SiO,-Moo, catalysts were prepared and applied to the hydrocracking of Athabasca bitumen. The activities of these catalysts were compared with that of a commercially available COO-MoO,/Al,O, (3: 13:86 wt %) catalyst.

EXPERIMENTAL The reaction apparatus and gas sampling are described in detail elsewhere6. The Athabasca bitumen was obtained from Suncor Ltd at Fort McMurray, Alberta. The properties of the bitumen are given by Kiiseoglu and Phillip@. Hydrocracking reactions were performed at 648 K (375”(Z), 673 K (400°C) and 698K (425°C) and at an initial hydrogen pressure of 7.0 MPa for 2 h. In each experiment, the reactor was charged with bitumen (25 g) and catalyst (2.5g). At the completion of reaction, the reactor was quenched by a flow of water through a cylindrical cooling jacket. Sepmation

and analysis

of products

Figure 1 shows the product separation scheme employed. After the reactor reached room temperature, the gas was passed through a wet test meter to determine its volume. Part of the gas was directed to the gas

FUEL, 1987, Vol 66, June

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1 min and counted in a y-ray spectrometer for 1 min. The silica content was calculated by difference. For comparison, a COO-MoO,/Al,O, (3: 13:86 wt %) catalyst was obtained from Ventron/Alfa Products, Danvers, MA, USA, and used as -40 mesh cm-’ powder. RESULTS

Figure

1

Product

separation

scheme

sampling bottle and saved for gas chromatographic analysis using a Carle 111 H series S gas chromatograph7. After the reactor reached atmospheric pressure, it was opened and the products collected. Coke and catalyst were separated from the liquid products by filtration using a medium size (10-15 pm) sintered glass filter and washed with methylene chloride. After evaporation of solvent, the asphaltene fraction was precipitated with pentane (1:40 v/v liquid oil/solvent) according to Syncrude Analytical Methods’. The pentane-soluble products were then separated into resins, aromatics and saturates using liquid chromatography’. Sulphur analysis was carried out using a combination of a hightemperature method’ and an oxygen flask methodlO. Preparation

FUEL, 1987, Vol66,

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The method of Tanabe and co-workers” was used in the preparation of catalyst. A mixture of ethyl orthosilicate (402cm3) and a 10% aqueous solution of ammonium molybdate (35.3 cm3) was dissolved in isopropanol (400 cm3). To this solution dilute nitric acid (pH = 1) was added and the solution held at 343-353 K (7CrSO”C) in a water bath for 16 h to facilitate gelation. The resulting gel was dried at 373 K (1WC) for 24 h, ground and screened on a 40 meshcm-’ screen. The catalyst was then calcined in air at 773 K (500°C) for 3 h. The SiO,-Moo, support was promoted with Co0 by mixing with an aqueous solution of cobalt nitrate [Co(NO,), .6H,O]. The resulting solution was evaporated, dried and calcined. The cobalt and molybdenum content of the catalyst was determined by neutron activation analysis using the Slowpoke nuclear reactor of the University of Toronto. The samples were irradiated under a neutron flux of 10” neutron cm-’ for

736

The product yield versus temperature curves for the hydrocracking of Athabasca bitumen in the absence of a catalyst6 and in the presence of SiO,-Moo,, 2.92 and 5.54 wt % Coo-promoted SiO,-Moo,, and commercially available COO-MoO,/Al,O, catalysts are shown in Figures 24. The yield of coke increased with temperature in the absence of a catalyst, and decreased in the presence of a catalyst. The yield of asphaltenes, maltenes and resins decreased continuously with reaction temperature in all cases, and the yield of gases increased. The yields of saturates and aromatics do not exhibit any simple trend. At 648 K (375°C) and 673 K (400°C) (Figure 7), coke yield was significantly lower for non-catalytic hydrocracking reactions than for catalytic reactions. Gates et ~1.‘~ suggest that the acid sites of the catalyst cause extensive cracking and thus increase the formation ofcoke. However, at 698 K (425°C) the formation of coke at lower yield in the presence of catalysts than in their absence is probably due to hydrogenation of coke precursors at the high temperature. The hydrocracking of asphaltenes is promoted by catalysts (Figure 8), as also observed by Nomura et a1.13. In the presence of catalysts, the asphaltene hydrocracking reactivity increases in the order SiO,-Moo,, 2.92 wt %

..

of catalyst

AND DISCUSSION

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370

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Temperature

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Figure 2 Conversion of bitumen for hydrocracking with SO,-MOO, catalyst. 0, Maltenes; A, resins; 0, saturates; 0, aromatics; V, gases; W, coke; A, asphaltenes

Hydrocracking

of bitumen

over binary metal oxides: R. ti. Ktiseoglu

et al.

separated from coal. The decrease in the concentration of asphaltenes with temperature is lower for non-catalytic reactions than for catalytic reactions. Gas production at all temperatures is low in the presence of CoO~MoO,/Al,O, and 5.54 wt % Co0 on

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Temperature ,‘C Figure 5 Conversion of bitumen for hydrocracking with CoOMoO,/AI,O, (3: 13 wt% COO/MOO,) catalyst. (For legend see Figure 2)

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Temperature, “C Figure 4 Conversion Co0 on SD-Moo,

of bitumen for hydrocracking catalyst. (For legend see Figure

with 5.54 wt% 2)

Co0 on SiO,-Moo,, 5.54 wt % Co0 on SiOzPMoO, The yield of asphaltenes and COO-MoO,/Al,O,. decreases as the reaction temperature increases for all reactions. This result is consistent with the results of of asphaltenes Miyake et a1.14 for the hydrocracking

390

400

410

Temperature, “C Figure 6 Conversion of bitumen (For legend see Figure 2)

for hydrocracking

without

FUEL,1987,Vol66, June

catalyst.

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Hydrocracking

of bitumen I

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390

over binary metal oxides: R. 0. Kiiseoglu

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The severity of hydrocracking of resins increases as the reaction temperature increases (Figure IO). The addition of a catalyst promotes cracking of the resins, particularly at higher temperatures (673 and 698 K). The 5.54 wt % Co0 on SiOzPMoO, catalyst was the most active in the conversion of resins.

430

Temperature,% Figure 7 Comparison with different catalysts. Co0 on SiO,-Moo,; MoO,/AI,O,

of coke yields from hydrocracking of bitumen W, SiOzPMoO,; A, 2.92 wt y0 0, 5.54 wt % Co0 on SiO,-Moo,; 0, COO-

l , No catalyst;

390

410

Temperature,72

T-----Figure 9 Comparison with different catalysts.

14

w ti 3

400

of gas yields from hydrocracking (For legend see Figure 7)

of bitumen

12

2

t 370

390

390

409

410

420

430

Temperature,'?2 Figure 8 Comparison bitumen with different

of asphaltene yields from hydrocracking catalysts. (For legend see Figure 7)

of

SiO,-Moo, catalysts (Figure 9). The SiO,-Moo, catalyst produced the most gas. The yield of gases was lowest for non-catalytic reactions at 648 K (375°C). The gas yield increases for both catalytic and non-catalytic reactions as the reaction temperature increases.

738

FUEL, 1987, Vol66,

June

, 379

390

I

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400

4io

1

420

430

Temperature,% Figure 10 Comparison with different catalysts.

of resin yields from hydrocracking (For legend see Figure 7)

of bitumen

Hydrocracking

of bitumen

The overall maltene yield decreases with increasing temperature (Figure I I). At 648 K (375”(Z), the yields of maltenes do not differ much for different treatments and are Y 85 wt %. However, at higher reaction temperatures, yields of maltenes are higher for catalytic hydrocracking reactions than for non-catalytic hydrocracking reactions. Moreover, more maltenes are formed when the hydrogenation component of the catalyst is increased. Thus with 5.54 wt “/, Co0 on SiOzPMoO, catalyst, more maltenes (80.0 wt ‘A at 673 K and 74.7 wt o/, at 698 K) are produced than with 2.92 wt % Coo-promoted catalyst (70.2 wt % at 673 K and 68.3 wt o/, at 698 K). The yields of saturates and aromatics are shown in Figures 12 and 13. The yield of saturates decreases with temperature in both the absence of a catalyst and in the presence of the SiO,-Moo, catalyst. However, the yield of saturates increases with temperature for all other catalysts used. The 5.54 wt % Co0 on SiO,-Moo, catalyst produced higher yields of saturates at all temperatures than the other catalysts. At 698 K (425”C), 47.3 wt % of saturates were produced in the presence of 5.54 wt % CoO/SiO,-Moo, catalyst. The aromatic content of the products shows that, as the reaction temperature increases, the yield of aromatics decreases, except for the reaction at 698 K (425°C) in the presence of a SiO,-Moo, catalyst (Figure 13). The yield of aromatics was low for the non-catalytic reactions and for the reaction in the presence of 2.92 wt y0 CoO/SiO,PMoO, catalyst. Increasing the hydrogenation component of catalysts did not increase the rate of hydrogenation of aromatics, presumably because the hydrogenation reactions become unfavourable at high temperatures (> 648 K)15. The aromatic content of the products was found to be less for reactions in the presence of SiO,MOO, and 2.92 wt % CoO/SiO,-Moo, catalysts than for reactions in the presence of 5.54 wt % CoO/SiO,P

over binary metal oxides: R. ti. Ktiseoglu I

I

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I

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Temperature,? Figure 12 Comparison of saturate yields from hydrocracking bitumen with different catalysts. (For legend see Figure 7)

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Temperature, "C Figure 13 Comparison of aromatic yields from hydrocracking bitumen with different catalysts. (For legend see Figure 7)

380

390

400

410

420

430

TemperaturePC Figure 11 Comparison of maltene yields from hydrocracking bitumen with different catalysts. (For legend see Figure 7)

of

of

MOO, catalyst, suggesting that the last-mentioned catalysts have higher cracking activity. The sulphur content of the maltenes fractions decreased with increasing reaction temperature and in the presence of catalyst (Figure 14). In the absence of a

FUEL, 1987, Vol 66, June

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Kiiseo@lu et al. CONCLUSIONS Of the catalysts tested, 5.54 wt % Co0 on SiO,-Moo, catalyst was found to be the most effective in maximizing the formation of oils (saturates and aromatics) and maltenes and minimizing the formation of resins and gases. SiO,-Moo, based catalysts were found to have higher activity in the hydrocracking of Athabasca bitumen than a commercially available COO-MOO, / Al,O, catalyst. Commercial COO-MoOJ/A1,O, catalyst produced the highest yields of aromatics (26 wt %) of all the catalysts tested. ACKNOWLEDGEMENTS This work was supported by a Strategic Grant from the Natural Sciences and Engineering Research Council of Canada. The work of Sheldon Hamilton in the sulphur analyses is gratefully acknowledged. REFERENCES 1

2

9-

1

370

300

I

390

I

I

I

400

410

420

430

3 4

with

5

Temperature,"C Figure 14 Changeofconcentration ofsulphur different catalysts. (For legend see Figure 7)

in maltenefraction

6 7 8

catalyst, the sulphur content of the maltenes fraction decreased from 3.62 to 2.06 wt % over the reaction temperature range 648-693K (375420°C). In the presence of 5.54 wt % CoO/SiO,-Moo, catalyst, the sulphur content of the maltenes fraction fell to 0.96 wt %. Both Coo-promoted catalysts and unpromoted catalysts were more effective in the hydrodesulphurization of the maltenes fraction than commercially available CoOMoO,/Al,O, catalyst.

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9 10 11 12 13 14 15

Cameron, J. J., O’Grady, M. A. and Parsons, B. I. Mines Branch Research Report, Department of Energy, Mines and Resources, Ottawa, Canada, 1969, R-217 Herrman, W. A. O., Mysak, L. P. and Belinko, K. CANMET Report, Department of Energy, Mines and Resources, Canada, 1977, 50 Ternan, M. and Parsons, B. I. US Patent, 1976, 4 176051 Speight, J. G. and Moschopedis, S. E. Fuel Process. Technol. 1979, 2, 295 Silva, A. E., Rohrig, H. K. and Dufresne, A. R. Oil Gas J. 26 March 1984, 81 Koseoglu, R. 0. and Phillips, C. R. Fuel 1987, 66, 741 Phillips, C. R., Haidar, N. I. and Poon, Y. C. Fuel 1985,64,678 Syncrude Canada Ltd, Syncrude Analytical Methods for Oil Sand and Bitumen Processing, 1979, p. 121 American Society for Testing Materials, 1979, ASTM D1552-79 Ahmed, S. M. and Whalley, B. J. P. Fuel 1972, 51, 90 Maruyama, K., Hattori, H. and Tanabe, K. Eul1. Chem. Sot. Japan 1977, SO(l), 86 Gates, B. C., Katzer, J. R. and Schuit, G. C. A. ‘Chemistry of Catalytic Processes’, McGraw-Hill, New York, 1979, 15 Nomura, M., Terao, K. and Kikakwa, S. Fuel 1981, 60, 699 Miyake, M., Kagajyo, T. and Nomura, M. Fuel Process. Technol. 1984, 9, 293 Sapre, A. V. and Gates, B. C. Ind. Eng. Chem. Process. Des. Deu. 1982, 21(l), 86