While the broadness of the pyrolysis profile of most kerogens is described well by a parallel reaction model, the pyrolysis profile at a constant heating rate for certain well-preserved algal kerogens is narrower than can be described by a single first-order reaction. Further, these kerogens show an acceleratory period under isothermal conditions that is inconsistent with any parallel or nth-order reaction model. Three different models (serial, Bouster, and three-parameter) are tested against isothermal and nonisothermal pyrolysis data for a few samples, with the conclusion that the three-parameter model fits well and is the most stable and reliable. The three-parameter model reduces to a first-order model when the acceleration parameter is zero. The overall activation energy and frequency factor from this model are very close to those of the T max-shift method recommended earlier.

A convenient, high-yield synthesis of 5//-dibenzo[a,c]cyclohepten-5-one is reported and the properties of dibenzo[fl,c]cycloheptatrienylidene are examined. As previously reported2 for 4,5-benzocycloheptatrienylidene, dibenzo [ti,c]cycloheptatrienylidene rearranges rapidly in solution to an arylcarbene (9-phenanthrylcarbene). When the annelated cycloheptatrienylidenes were generated in the presence of dienes, Diels-Alder adducts of the cyclopropene intermediates were obtained. The molecular geometry of the single furan adduct of dibenzo[a,c]cycloheptatrienylidene was determined from an analysis of lanthanide-induced proton nmr shifts. The geometry of the adducts of both of the carbenes with cyclopentadiene is shown to be the endo-anti isomers. These are the products expected from cycloaddition of 3-monosubstituted cyclopropenes with this diene. The furan adduct was obtained under both thermal (125°) and photochemical (30 and -60°) conditions. Tetracyclone adducts were obtained in thermal reactions and cyclopentadiene and butadiene adducts were obtained from low-temperature ( -60°) reactions. The adducts were shown not to be secondary photoproducts, and a two-step thermal process has been ruled out. Also, irreversible cyclopropene formation competitive with rearrangement is shown to be an unsatisfactory explanation of the experimental results.

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nth-order kinetic parameter percent of dry bitumen free shale solubilized after treatment time t percent of dry bitumen-free shale solubilized after treatment time t = a percent of dry bitumen-free shale solubilized after treatment time t = 0 percent of dry bitumen-free shale solubilized as species having molecular weight x at time t percent of dry bitumen-free shale solubilized as species having molecular weight r at time t = percent of dry bitumen free shale solubilized as species having molecular weight x at time t = 0 molecular weight for which k ( 7 ) = K w ( x , t ) weight fraction of species having molecular weight Acknowledgment. The Fullbright fellowship for M.T. provided by the Moroccan-American Commission for Educational and Cultural Exchange and coordinated by Amideast is gratefully acknowledged. Our appreciation to ONAREP for providing the samples used in this study is also acknowledged. Funds for this research were also provided, in part, from the O.U. Energy Resources Institute and Oklahoma Mining and Minerals Resources Research Institute.x at time t.Ammonia (NHJ evolution during pyrolysis of three Green River Formation shales and one Eastern (Devonian) shale was studied. The yields of NH3 from Fischer assay type experiments were measured with an NH3-sensing electrode, and the time-dependent rate of NH3 evolution was measured with a triple-quadrupole mass spectrometer. We varied the peak temperature (PT) of the pyrolysis from 350 to 750 OC and the heating rate from 1 to 50 OC/min. The NH3 yields increased rapidly above the oil-generating temperatures to a maximum at PT -700 "C and then decreased at PT > 700 OC because of the decomposition of NH3. The NH3 yield showed no dependence on the heating rate at PT < 550 OC and decreased with increasing heating rate at higher peak temperatures. For Green River Formation shales, the yield of NH3 at PT < 500 "C reflected the organic nitrogen content. The extent of NH3 decomposition varied with gas environments, solid surface, and the conditions of the retort can. Because steam works as an inhibitor for the decomposition reaction, we used steam as a retorting gas to obtain the total yield of NH3. We developed a kinetic model for NH3 evolution; it takes into account NH3 generation from organic and inorganic nitrogen sources and NH3 decomposition.

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