Green River oil shales pyrolysis

BURNHAM AND SINGLETON Green River Oil Shale Pyrolysis... 

Table III. Heats of Pyrolysis for Green River Oil Shale and Devonian Shale (Unit cal/g)...

High-Pressure Pyrolysis of Green River Oil Shale... 

Oil shales contain large quantities of insoluble organic matter, kerogen, which upon pyrolysis at higher temperatures, yields oil products. Kerogen, which usually represents 80-90% of the total organic matter in Green River oil shales, is neither soluble in aqueous alkaline/acidic solvents nor in the common... 

This proposed silicate mineral catalytic effect is further demonstrated by TG measurements of the kerogen concentrate, Sample D, which show a decrease in the net pyrolysis yield from 68.8 wt% for the bitumen-, carbonate-free Sample C to 57.6 wt% for the now silicate-free sample. These results suggest that the optimum pyrolysis oil yield is achieved for Green River oil shales which are carbonate-free, but still retain their original silicate mineral concentration or, possibly, an increased silicate concentration. 

NMR measurements have been combined with elemental and mass balance data to determine the extent of aromatization during pyrolysis. Hershkowitz et al7 were the first to quantify the increase in the aromatic carbon formed during pyrolysis of Colorado oil shale. Their experiments were conducted at a slow heating rate, under high pressure (2600 kPa) N2 or H2 atmospheres, at temperatures up to 600°C, followed by a 10 min soak period at this temperature. In an N2 atmosphere, the total aromatic carbon in the products increased by 83% over that in the raw shale. In H2 the increase was only 17%. In addition, 87% of the raw shale carbon was recovered in the oil when heated under H2, compared with 67% under N2. An increase in aromatic carbon of about 83% has been observed in pyrolysis studies of Green River oil shale at heating rates of l-720 Ch to 500°C. ... 

Figure 3 shows model DSC data on a suite of Green River oil shale samples illustrating the sensitivity of the pyrolysis... 

More recently, Kelemen et al. [154] discussed the pros and cons of XPS, XANES, and N NMR for characterizing and identifying the chemical forms of nitrogen in complex carbonaceous systems. They used both XPS and N NMR quantitatively to study kerogen obtained by demineralization of a Green River oil shale and of a peat sample, as well as chars obtained by pyrolysis and isoquinoline- and quinoline-derived chars. The inherent advantage of using a combination of these methods has thus been demonstrated. 

Utilisa tion of shale oil products for petrochemical production has been studied (47—51). The effects of prerefining on product yields for steam pyrolysis of shale oil feed and the suitabiUty of Green River shale oil as a petrochemical feedstock were investigated. Pyrolysis was carried out on the whole oil, vacuum distillate, and mildly, moderately, and severely hydrogenated vacuum distillates. 

There is no geological or chemical definition of an oil shale. Any rock yielding oil in commercial amount upon pyrolysis may be considered as an oil shale. The composition of the inorganic fraction may vary from a shale where clay minerals are predominant, such as the Lower Jurassic shales of Western Europe (particularly France and West Germany.), to carbonates with subordinate amounts of clay and other minerals, such as the Green River shales of Colorado, Utah and Wyoming. 

Methane. The methane evolution profiles for all five shale samples are surprisingly similar, but occur at significantly higher temperatures than has been observed (2) for the Green River shale. Although some methane evolution accompanies the oil formation, the major part is formed in the secondary pyrolysis region. At least three major processes with maxima in the vicinity of 500, 580 and 700°C appear to contribute to the total methane formation. Activation energies for these processes were determined for Condor carbonaceous shale and are summarised in Table 6. 

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