Virgin bitumen

Source Louisiana Virgin Hydrodesulfurized Virgin Hydrodesulfurized Oklahoma California Gilsonite Bitumen... 

Characterization of Feedstock and Catalysts. The elemental analysis and physical properties of various feedstocks used in this study are given in Table I. The data show that the virgin bitumen contains... 

Virgin Bitumen Vis- breaking Products Maltenes Hydro- pyrolysis Products... 

The virgin bitumen is vaporized only partially at normal cracking temperatures and obtaining reproducible catalyst-bitumen contact presents a significant problem. Two modes of operation were used—semibatch and batch. In the semibatch mode, the catalyst and feed were preheated separately before contact was made in a downflow fixed-bed reactor. Preheat of the feed was held to 350°C to minimize thermal-cracking reactions prior to contact. This reactor had contact between bitumen and catalyst at reaction temperature, but it did not achieve uniform contact and meaningful cat-to-oil ratios. The batch mode provided ultimate contact with the bitumen but it had longer heat-up times... 

Symbol designation Bt (virgin bitumen) S/A (silica-alumina catalyst) MS (molecular sieve catalyst) SB (semibatch Cat A mode) B (batch mode) f (powdered catalyst) T (thermal coking). 

Symbol designation M (maltenes from virgin bitumen) VB (visbroken bitumen) HP (hydropy roly zed bitumen). See also Table IV. 

The virgin bitumen and fractions were characterized by 13C NMR. Results shown in Figure 1 show that the spectra of the maltenes and the virgin bitumen are virtually superimposable. The high resolution spectra reveal several resolved peaks in the saturates region attributable to n-alkyl species, some of which are of notably lower intensity in the maltenes spectrum, but in general, the vast majority of the saturates carbon (>80%) is found under the envelope and is probably due to complex alicyclic and/or isoparaffin structures. These results are consistent with an earlier observation (1) that saturated hydrocarbons from Uinta Basin bitumen are high in naphthenes and low in free paraffins. 

Property Virgin Bitumen Maltenes Asphaltenes Weighted Average of Maltenes and Asphaltenes Asphaltene-Enhanced Bitumen8... 

Simulated Distillation Results. Important insight concerning the molecular-size distribution of asphaltenes vs. maltenes is gained by the simulated distillation data. The boiling point distribution curves are shown in Figure 3. These curves were drawn as follows. Quantitative simulated distillation data was obtained on the virgin bitumen and the maltenes. Direct information is obtained up to a nominal boiling point of 535°C shown by the vertical dashed line. The area under the curve for the nonvolatile portion is... 

Figure 3. Simulated distillation boiling point curves for virgin bitumen, mal-tenes, and asphaltenes...

The results in Table III show that the virgin bitumen that contains the asphaltenes produced relatively more gas and nonhydrocarbon products than did the maltenes. This trend with respect to gases and liquids appears to be confirmed by the results of the run with the asphaltene-enhanced bitumen however, appreciable quantities of coke were formed at the reaction conditions used and good material balances on this run were not achieved. Without essentially complete reduction of coke formation by hydropyrolysis, the significance of results for the asphaltene-enhanced bitumen are suspect. Removal of carbon in the form of coke will have an unknown effect on results that may not be attributable to asphaltenes. These results are included principally as negative results to show the dramatic effects that can result if asphaltenes are not fully dispersed and coke formation is not inhibited during hydropyrolysis. 

In an attempt to quantify the effect of asphaltenes, a calculation that synthesized results of a hypothetical feed of 100% asphaltenes was made based on the maltene and virgin bitumen results. This calculation is useful to break out the relative effect of asphaltenes and maltenes to the total results. The calculation is based on the general relationship 0.794 (maltene results) + 0.206 (asphaltene results) = virgin bitumen results. Results of this calculation show that asphaltenes have a marked effect on increasing the gas production, and correspondingly, require appreciable quantities of hydrogen for conver-... 

Values for asphaltenes were calculated based on the weighted difference between results for the maltenes and the virgin bitumen. 

Small amounts of coke that may be formed from the maltene and virgin bitumen feeds are counted as gases in the calculations. rfNA—not available. 

Perhaps one of the more significant results of this work can be seen in comparison of asphaltenes produced from maltenes and those from virgin bitumen. Taking into account the condensable product yields, it can be shown that hypothetical yield of product asphaltenes from precursor asphaltenes is only about double that of asphaltenes yield from maltenes [e.g., by the previous method of calculation 0.794 (0.11 x 0.803) + 0.206 (X) = 0.15... 

Product Properties Maltene Virgin Bitumen Asphaltene- Enhanced Bitumen... 

The structure and chemistry of tar sand bitumen asphaltenes were studied indirectly by inference from processing and characterization of virgin bitumen and deasphaltened bitumen (maltenes). Results differ significantly from those derived from characterization of asphaltenes as isolated... 

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