Reduction kinetics of iron oxides used for hydrogen production in various gas media

Abstract

The paper examines the physicochemical features of the reduction of iron oxides (as multicomponent scale waste) in various gases: H 2, CH 4 , CO, and generator gas containing 33% CO and 67% N 2 . At the initial stage of reduction, the activity of the gases decreases in the above sequence. It is analyzed how blocking of iron oxide surface with carbon formed in the conversion of methane and carbon monoxide influences the reduction processes. The deposition of carbon in these media is intensified when the reduction degree is higher than 70%. The thermodynamic dependencies of oxide reduction on the ratio of P CO 2 /Pco partial pressures are given. Noteworthy is high sensitivity of Fe 3 O 4 and FeO reduction to the change in CO 2 content.The papers [1, 2] consider the reduction of iron oxides contained in a multicomponent mixture of metallurgical waste with the purpose of their use in hydrogen production with the iron vapor method. Metallurgy can use gases with different reducing properties, such as H 2 , CH 4 , CO, and generator gas containing different gas components. The gases differ in physical and chemical properties, which greatly determine the reduction mechanism and rate and the properties of metals reduced.This paper analyzes the effect of the above gases on the reducing processes, kinetic indicators, chemical transformations, and features of reduction products, and their effect on the surface activity of reduced oxides used in redox cycles in hydrogen production with the iron vapor method.Characteristics of the material in question containing to 70% iron oxides are provided in [1]. There are no accompanying chemical transformations during reduction in hydrogen, and no byproducts form. The use of carbon monoxide determines the probability of Boudoir's reversible reaction. Possible deposition of carbon on the surface of oxide being reduced can change parameters of chemical transformations, including the reducing mechanism. The use of methane and, possibly, mixed (H 2 , CH 4 , CO, CO 2 ) effluent metallurgical gases makes the process complex, which involves the conversion of gases in the reaction area on the surface of reduced oxides. The conversion of methane [2] can lead to the formation of hydrogen and deposition of carbon, which can change chemical processes. Active carbon may not only participate in reducing processes but also block the reaction surface of reduced oxide.Kinetic studies were conducted using an automatic gravimetric unit measuring the weight with an accuracy of 1 ⋅ 10 -5 g. This accuracy permitted analyses in different molecular and dissociated gas media at pressures between

Syngas Production from Chemical‐Looping Reforming of Methane Using Iron‐Doped Cerium Oxides

“…Carbon intermediates [C] a was a reported high‐active component in the reduction of iron oxide,, which would accelerate the production of metallic iron Fe 0 . According to this reaction features, it could be assumed that the production of H 2 and CO would show similar acceleration effect.…”

Performance and Properties of Suspension Plasma Sprayed Metal‐Supported Cu‐Co‐Ni‐SDC SOFC Anodes in Methane

“…On components such as these, it has been shown that iron oxides are particularly important in increasing coking rates because they can enhance the surface area of active Fe particles at the surface when the oxides are reduced , . Several studies have demonstrated the reducibility of high surface area iron oxide catalysts in CH 4 and H 2 atmospheres , . Therefore, it is suggested that local reduction of iron oxides formed on the supports during plasma spray processing or cell testing in this study contributed to the enhanced coking behavior in CH 4 of the anodes on the metal supports.…”

How to synthesize pure Li2−xFeSi1−xPxO4/C (x = 0.03–0.15) easily from low-cost Fe3+as cathode materials for Li-ion batteries

“…51 The amount of produced NH 3 is small so that it could adsorb on the surface of material particles and/or fill in the porosity in the large for a period of time. 53,54 To confirm this mechanism, as an example, the gas produced in the process of calcination between 350-650°C with the molar ratio of n(NH 4 H 2 PO 4 )/n(NH 4 H 2 PO 4 +SiO 2 )=20% was collected and analyzed through the gas chromatography. Compared with the H 2 atmosphere from the outside of the block of the reactants, the needed amount of H 2 produced by this system itself should be far little and the security is higher obviously.…”