Abstract:
A process is provided for hydrocracking a heavy oil bitumen and chemically related feedstock. The process comprises reacting said feedstock with a gaseous superacid in the presence of hydrogen with or without the use of a hydrogen transfer agent to thereby yield lower boiling point distillates.

Description:
FIELD OF THE INVENTION 
     This invention relates to a process for the catalyzed hydrocracking of heavy hydrocarbons into a refinery treatable product. 
     BACKGROUND OF THE INVENTION 
     Hydrogenation processes for the upgrading of heavy cretaceons crude oil and bitumens are well known. Upgrading processes are normally carried out to remove or reduce the contaminants in the oil and to convert the heavier components of the oil into lower boiling point hydrocarbon products. The contaminants include the heteroatoms oxygen, sulphur and nitrogen and the metals vanadium, nickel and iron. 
     Current commercial upgrading processes typically involve the use of a heterogeneous catalyst, exemplary of which would be cobalt, molybdenum or nickel sulfides deposited on an alumina substrate. Deleteriously, the higher molecular weight components of the heavy oils tend to accumulate on the catalyst pellet surfaces, clogging the pore system and thus reducing the rate of hydrogenation. Ultimately, the deposition of coke and metals on the pellet surface will despoil the catalytic performance. This becomes a serious operational problem when feedstocks such as bitumen, which are high in asphaltenes are hydrocracked. 
     The types of reactor employed in hydrocracking processes typically comprise a tubular reactor containing a fixed bed of the catalysts mentioned supra, or a fluidized bed of catalyst. Recovery of spent catalyst, and indeed replacement thereof, is a major expenditure in the process. 
     Typical hydrocracking reaction conditions are undertaken at high temperatures, of the order of between 400°-840° C. and at high pressures namely about 2,000-3,000 psi or higher. 
     It would be desirable, therefore, if a process not requiring a solid catalyst and requiring less severe reaction conditions could be arrived at. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a process for hydrocracking a heavy hydrocarbon to produce lower boiling point distillates. More specifically, the process involves reacting the feedstock with a gaseous superacid in the presence of hydrogen. 
     Preferably, addition of a hydrogen transfer agent to the reactants would be made. 
     Typical heavy hydrocarbon feedstocks would include heavy oil, bitumen or chemically related substances, for example, asphaltenes. 
     As the catalytic superacidic fluorine compound, acids which contain elements of group III, IV and/or V of the periodic table could be considered. Exemplary superacids would include, but are not limited to, HF.BF 3 , H 2  SiF 6  and HPF 6 . Preferably, the superacid utilized would comprise HF.BF 3 . 
     As stated earlier, it is a preferred condition that the hydrogenation reaction take place in the presence of a hydrogen transfer agent. Suitable hydrogen transfer agents would comprise the cycloalkanes and low molecular weight alkanes. Particularly suitable hydrogen transfer agents include methylcyclohexane (MeCH), methylcyclopentane, dimethylcyclohexane or dimethcyclopentane. The preferred hydrogen transfer agent would be methylcyclohexane. 
     Preferred conditions for the hydrogenation reaction are such that the reaction is conducted at temperatures ranging from between 25° C. and 300° C. A preferred temperature range would be between 170° C. and 250° C. It will be readily appreciated however, by one skilled in the art, that if the temperature is too low, no reaction takes place and if too high, molecular over-degradation will result. 
     The requisite reaction time would probably range between one to twenty four hours. However, there exists the possibility of instantaneous reaction, and thus the time is not to be restricted to this stated range. 
     Again, there is no criticality with respect to pressure. Typically, the HF.BF 3  pressure would be 500 psi. 
     As a result of practising the present process, the bitumen or heavy oil feedstock is rendered into lower boiling point distillates. Advantageously under the mild conditions of the process the bitumen is converted to volatiles in at least a 56% yield in one hour. Additionally, removal of the undesirable heteroatoms is effected. Furthermore, a reduction in the vanadium, nickel and iron content takes place. 
     Following the hydrogenation reaction, the superacid HF.BF 3  has to be removed prior to further processing of the reaction products and this is easily and inexpensively done because of the high volatility and solubility of the superacid in water. Thus, the catalyst is reusable without involving a complex regeneration technique. 
     The main facets of HF.BF 3  superacid catalysis may be summarized as follows: 
     the catalyst molecule diffuses to the substrate molecule; 
     the HF.BF 3  activates the hydrocarbon, unlike conventional catalysts which activate the hydrogen molecule; 
     catalysis proceeds efficiently at low temperature and hydrogen pressure; 
     catalysis involves an ionic mechanism versus the free radical mechanism of conventional catalysis and therefore it results in different, more desirable products; and 
     fluorine incorporation into the bitumen products does not occur. 
     When these characteristics are taken in conjunction with the ready separability of HF and BF 3  from the hydrocracking products and with their reusability it becomes evident that the HF.BF 3  superacid catalyzed hydrocracking of oil sand bitumens offers good potential for commercial application. 
     Broadly stated the invention comprises a process for hydrocracking a heavy oil bitumen, or chemically related feedstock, which comprises reacting said feedstock with a gaseous superacid preferably in the presence of a hydrogen transfer agent and hydrogen to thereby yield low boiling point distillates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an infrared spectrum (IR) of the &#34;saturate&#34; fraction of Cold Lake (CL) superacid-treated asphaltene, stored under N 2 . 
     FIG. 2 is an IR spectrum of the &#34;saturate&#34; fraction of CL superacid - treated asphaltene exposed to air. 
     FIG. 3 is a gas chromatogram of the &#34;saturate&#34; fraction of CL superacid - treated asphaltene. 
     FIG. 4 is a mass chromatogram (GCMS) of the &#34;saturate&#34; fraction of CL superacid - treated asphaltene. 
     FIG. 5a, 5b and 5c are a mass spectra of scans 246, 261 and 280 (C 16  H 24 ) of FIG. 4. 
     FIGS. 6a, 6b and 6c are a mass spectra of scans 286 (C 16  H 24 ), 294 and 297 (C 17  H 26 ) of FIG. 4. 
     FIG. 7 is a mass chromatogram (GCMS) of the &#34;saturate&#34; fraction of CL superacid - treated asphaltene after ionic hydrogenation. 
     FIGS. 8a and 8b are the mass spectra of scans 237 (C 16  H 30 ) and 249 (C 17  H 32 ) of FIG. 7. 
     FIG. 9 is a chemical ionization mass chromatogram GCMS of the &#34;saturate&#34; fraction of CL superacid - treated asphaltene. 
     FIGS. 10a, 10b, 10c are the mass spectra of scans 1082(a), 1102(b) and 1156(c) of FIG. 9. 
     FIG. 11 is the gas chromatogram of the &#34;saturate&#34; fraction of superacid - treated CL bitumen. 
     FIG. 12 is the gas chromatogram of the &#34;saturate&#34; fraction of Athabasca bitumen. 
     FIG. 13 is a plot of the total recovery as a percentage of the starting material utilized versus the volume of MeCH added. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Having reference to the accompanying drawings, there is provided an alternative process to the conventional catalytic hydrocracking of oil sand bitumens, heavy oil or chemically related feedbacks. More specifically, the process involves a superacid-catalyzed hydrocracking process which proceeds via a free radical (or ionic) mechanism. The preferred superacid catalyst would be in the gaseous state. 
     The sole superacid which is in the gaseous state is HF.BF 3 , or fluoroboric acid. However, other superacids, or the salts thereof may be contemplated for use as catalysts. Exemplary superacids would include, but are not limtied to HF.BF 3 , H 2  Si F 6  and HPF 6  or the like. 
     It is desirable that the reaction take place in the presence of a hydrogen transfer agent. Suitable hydrogen transfer agents would include the cycloalkanes and low molecular weight alkanes. A particularly suitable hydrogen transfer agent is methylcyclohexane (MeCH). Contrary to expectation it was found that using MeCH as the solvent desirably resulted in the oligomerization of MeCH to produce conjugated olefinic oligomers. It had been anticipated that the MeCH would be inert under these experimental reaction conditions. Upon exposure to air, these oligomers reacted with oxygen, turning the clear liquid of the separated oligomers to a partially, soluble, translucent gum. 
     Various experiments were conducted both in the presence and absence of the MeCH solvent. In the presence of MeCH, the yields of non-volatile products were higher and were dependent upon the amounts of solvents used, as can be illustrated in tables 1-7 given hereinafter. 
     The hydrogenation reaction, typically, takes place under mild reaction conditions. The reaction temperatures range between 25° C. to 300° C. A preferred temperature between about 170° C. and 250° C. The reaction time can range from an instantaneous time to about 24 hours. Typically, a preferred reaction time is from about one hour to about twenty four hours. Preferred conditions for hydrocracking are such that the reaction is conducted at a pressure of 500 psi H 2 . 
     
                       TABLE 1______________________________________Superacid treatment of CL asphaltene______________________________________Reaction conditions:     210° C.     500 psi H.sub.2     500 psi BF.sub.3      50 mL HF      30 mL MeCH      2.50 g asphaltene     Reaction time 24 hrsProduct yields:maltene        5.59 g         86.8% of productasphaltene     0.85 g         13.2% of productClass composition of maltene:Saturates      66.3Monoaromatics  13.2Diaromatics    4.4Polyaromatics  2.4Polar          13.6Elemental analysis:          maltene        asphalteneC              87.92          81.66H              10.30          7.20N              0.06           0.87S              0.23           0.81O              1.19           3.77MW             329            ND(H/C).sub.atomic          1.53           1.05______________________________________ 
    
     
                       TABLE 2______________________________________Superacid treatment of CL bitumen______________________________________Reaction conditions:     285° C.     500 psi H.sub.2     500 psi BF.sub.3      50 mL HF      5 mL MeCH      3.5 g bitumen      24 hrs reaction timeProduct yields:maltene   1.87 g   85% of products                           53.4% of bitumenasphaltene     0.33 g   15% of products                           9.4% of bitumenClass composition of maltene:Saturates 34.4Monoaromatics     14.2Diaromatics     11.2Polyaromatics     17.7Polar     22.5Elemental analysis:     maltene  asphalteneC         84.25    80.18H         11.31    7.83N         0.22     1.05S         3.49     7.84O         0.79     2.27MW        447      2,345(H/C).sub.atomic     1.6      1.16______________________________________ 
    
     
                       TABLE 3______________________________________Superacid treatment of Suncor Coker Feed bitumen______________________________________Reaction conditions:     200° C.     500 psi H.sub.2     500 psi BF.sub.3      50 mL HF      30 mL MeCH      2.64 g bitumen      24 hrs reaction timeProduct yields:maltene   5.5 g    89.4% of products                           208% of bitumenasphaltene     0.65 g   10.6% of products                           24% of bitumenClass composition of maltene:Saturates 54.4Monoaromatics     22.7Diaromatics     2.7Polyaromatics     0.6Polar     19.6Elemental analysis:     maltene  asphalteneC         87.95    77.44H         10.88    7.13N         0.02     1.49S         0.76     7.56O         0.76     6.38MW        324      ND(H/C).sub.atomic     1.47     1.10______________________________________ 
    
     
                       TABLE 4______________________________________Superacid treatment of Suncor Coker Feed asphaltene______________________________________Reaction conditions:     200° C.     500 psi H.sub.2     500 psi BF.sub.3      50 mL HF      30 mL MeCH      2.5 g bitumen      24 hrs reaction timeProduct yields:maltene   5.0 g    84.9% of products                           200% of as-                           phalteneashpaltene     0.89 g   15.1% of products                           35.6% of as-                           phalteneClass composition of maltene:Saturates 39.2Monoaromatics     41.4Diaromatics     1.0Polyaromatics     0.0Polar     18.3Elemental analysis:     maltene  asphalteneC         87.35    76.46H         10.81    7.51N         0.0      1.81S         0.74     7.33O         1.14     6.88MW        332      ND(H/C).sub.atomic     1.47     1.17______________________________________ 
    
     
                       TABLE 5______________________________________Superacid treatment of Suncor Coker Feed bitumenand asphaltene. Effect of the quantity of MeCH added..sup.aExpt. No.   1      2       3    4     5    6______________________________________Bitumen (g) 2.69   2.88    --   --    3.08 --Asphaltene (g)       --     --      2.50 2.50  --   2.50MeCH (mL)   5      30      5    30    15   15______________________________________ .sup.a Conditions: 1 h, 200° C., 500 psi H.sup.2, 500 psi BF.sub.3 50 mL HF, reactor volume 25 mL 
    
     
                       TABLE 6______________________________________Gravimetric results of superacid experiments on CokerFeed bitumen and aphaltene                           TotalAsphaltene        Maltene       recoveryVolume           % of            % of   % ofMeCH    % re-    starting % re-  starting                                   starting(mL)    covered  material covered                            material                                   material______________________________________Bitumen5 mL    18.5      8.1     81.5   35.7   43.815 mL   13.1      9.4     86.9   62.3   71.730 mL    5.8     11.7     94.2   191.6  203.3Asphaltene5 mL    57.1     44.6     42.9   33.5   78.115 mL   54.6     49.2     45.3   40.8   90.030 mL   19.1     38.4     80.9   161.6  200.0______________________________________ .sup.a Asphaltene content of bitumen was 15.5%. 
    
     
                       TABLE 7______________________________________Class composition of the maltenes.sup.a        Superacid experiment     Starting 1 (bi-  2 (bi-                            3 (as- 4 (as-Fraction  material tumen)  tumen)                            phaltene)                                   phaltene)______________________________________Saturates 24.9     27.0    58.9  20.8   42.7Monoaromatics     10.8     9.6     18.2  4.6    22.2Diaromatics     8.5      4.4     0.5   1.5    1.4Polyaromatics     20.0     8.7     1.0   6.0    1.1Polars    35.8     50.2    21.4  67.0   32.6______________________________________ .sup.a As wt % of maltene. Separation done on an alumina/silica gel column. 
    
     Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever.