Kinetics and thermodynamics evaluation of carbon dioxide enhanced oil shale pyrolysis

Abstract

The pyrolysis process of oil shale is significantly affected by atmospheric conditions. In this paper, the pyrolysis experiments of oil shale under non-isothermal conditions are carried out using nitrogen and carbon dioxide as heat-carrying fluids. The results show that the activation energy of the second stage of oil shale pyrolysis under carbon dioxide is less than that under nitrogen. The thermodynamic analysis of the second stage of oil shale pyrolysis shows that Gibbs free energy, activation enthalpy and activation entropy are higher under carbon dioxide than those under nitrogen, which obeys the law of carbon dioxide promoting oil shale pyrolysis. In addition, the volatile release characteristics of oil shale in the second stage of pyrolysis were analyzed, which proves that the volatile release characteristics of oil shale under carbon dioxide are higher than that under nitrogen. Therefore, carbon dioxide is helpful to promote the pyrolysis of oil shale and increases the release of volatile substances during pyrolysis.

CO2-Assisted Chemical Looping Process of Lignocellulosic Biomass: Thermogravimetric Behaviors, Kinetics, and Product Distribution

“…The different kinetic models employed might cause the inconsistency. In addition, it was observed that HTZ-E was affected by V CO 2 ; a high concentration of CO 2 increased the reaction rate and the efficient collision rate (i.e., the pre-exponential factor), and HTZ-E increased accordingly due to the compensation effect …”

“…In addition, it was observed that HTZ-E was affected by V COd 2 ; a high concentration of CO 2 increased the reaction rate and the efficient collision rate (i.e., the pre-exponential factor), and HTZ-E increased accordingly due to the compensation effect. 26 Pyrolysis and Reduction. Pyrolysis and Reduction Behaviors.…”

Study on the pyrolysis behavior and kinetics of Jimusar oil shale with H2O/CO2 injection

“…The FWO method was used to validate the kinetic parameters, based on which g(α) was expressed using Eq. ( 10): (10) Combined with the mechanism functions f(α) = 1-α and g(α) = -ln(1-α) for the second stage of JM oil shale pyrolysis after the N 2 injection, f(α) = [-ln(1-α)] -1 and g(α) = (1-α)ln(1-α) + α after the CO 2 injection, and 2 after the H 2 O injection, α was solved using Eq. ( 11): (11) shale pyrolysis in different atmospheres and at different β were determined; the results are given in Table 4.…”

“…The second stage is the main stage of organic matter decomposition in oil shale and requires a high amount of energy to break the chemical bonds in the organic matter. Zhao et al [10] conducted pyrolysis experiments on oil shale under non-isothermal conditions with N 2 and CO 2 as thermal-carrying fluids and confirmed that compared with N 2 , CO 2 reduced the activation energy of oil shale because it redounds the liberation of volatile matter during the second stage of oil shale pyrolysis.…”

Effect of N2 and CO2 on shale oil from pyrolysis of Estonian oil shale

“…They explained that since the heat capacity of N2 is higher than CO2 therefore, the heat transfer resistance is larger as well, leading in greater dispersion of oil shale pyrolysis. [21]. These results show that different oil shales -due to their complex structures and different properties -show different behaviors and therefore, predicting them may not lead into the most correct conclusion.…”