Kinetics of the Reactions Prevailing during Packed‐Bed Chemical Looping Combustion of Syngas using Ilmenite

Abstract

Chemical looping combustion has been identified as a very promising technology for power production with integrated carbon dioxide capture. The objective of this work is to study the kinetics of all reactions that are important in the combustion of syngas in a packed‐bed chemical looping reactor by using ilmenite as an oxygen carrier. The reaction kinetics of reduction, with hydrogen and carbon monoxide, and oxidation, with oxygen, of ilmenite‐based pellets have been determined in a thermogravimetric analyzer. The shrinking core model for a spherical geometry was used to obtain the kinetic parameters by considering mixed control by chemical reactions and diffusion through the product layer for all reaction involved. The reduction rate of ilmenite by hydrogen was at least an order of magnitude higher than that by carbon monoxide (especially at higher particle conversions) and the activation energies were found to be 45 and 30 kJ mol−1 for reduction with hydrogen and carbon monoxide, respectively. For the oxidation reaction, a much lower apparent activation energy of 5 kJ mol−1 was found, which indicated that the temperature did not have an important effect on the oxidation kinetics of ilmenite. In addition, the catalytic activity of ilmenite for water gas shift (WGS) was measured in a micro fixed‐bed reactor. An empirical power‐law model was used to describe the kinetics of the WGS reaction over ilmenite.

Determination of the oxidation kinetics of high loaded CuO-based materials under suitable conditions for the Ca/Cu H2 production process

“…The A shrinking core model (SCM) that has been able to describe reduction [26,29,38,41] and oxidation [26,36,39,41] reactions of different metal compounds was applied in Therefore this expression has been applied for plate-like geometry in the case of the material in powder form and cylindrical geometry for the pellet.…”

“…Although very important for the design of Ca-Cu loops, an extensive work specifically dealing with the oxidation kinetics of CuO-based materials is still lacking in the literature . Up to now, different gas-solid models such as the shrinking core model (SCM) [26,29,[36][37][38][39][40][41], the changing grains size model (CGSM) [39,42,43] and the nucleation models [44,45] have been reported in the literature to determine the kinetic parameters of oxidation reactions of different metal oxide materials. Regarding to the oxidation reaction, García-Labiano et al [26], applied the SCM to determine the kinetic behavior of a 10%wt.…”

Recent Insights into the Production of Syngas and Hydrogen Using Chemical Looping-Steam Reforming (CL-SR)

“…However, few investigations in the literature have focused on determining the kinetic characteristics of different oxygen carriers. Knowledge of kinetics data is critical in the design of a CL-SR process because it dictates the solid inventory required in the reactor, dimension of the reactor, and also the flow conditions . In the CL-SR process, the kinetic parameters such as rate, order, and activation energy are the function of various parameters such as temperature, concentration, and most importantly the type of oxygen carrier used.…”

Gas Switching as a Practical Alternative for Scaleup of Chemical Looping Combustion

“…Ilmenite has been shown to catalyze the WGS reaction and kinetics of this reaction has recently been determined . It is not yet known how the catalytic activity of ilmenite varies with the oxygen carrier conversion, but this study assumes that the catalytic reaction rate is proportional to the degree of oxygen carrier reduction [Eqs.…”