Materials for Chemical-Looping with Oxygen Uncoupling

Abstract

Chemical-looping with oxygen uncoupling (CLOU) is a novel combustion technology with inherent separation of carbon dioxide. The process is a three-step process which utilizes a circulating oxygen carrier to transfer oxygen from the combustion air to the fuel. The process utilizes two interconnected fluidized bed reactors, an air reactor and a fuel reactor. In the fuel reactor, the metal oxide decomposes with the release of gas phase oxygen (step 1), which reacts directly with the fuel through normal combustion (step 2). The reduced oxygen carrier is then transported to the air reactor where it reacts with the oxygen in the air (step 3). The outlet from the fuel reactor consists of only CO 2 and H 2 O, and pure carbon dioxide can be obtained by simple condensation of the steam. This paper gives an overview of the research conducted around the CLOU process, including (i) a thermodynamic evaluation, (ii) a complete review of tested oxygen carriers, (iii) review of kinetic data of reduction and oxidation, and (iv) evaluation of design criteria. From the tests of various fuels in continuous chemical-looping units utilizing CLOU materials, it can be established that almost full conversion of the fuel can be obtained for gaseous, liquid, and solid fuels.

Kinetic analysis of a Cu-based oxygen carrier: Relevance of temperature and oxygen partial pressure on reduction and oxidation reactions rates in Chemical Looping with Oxygen Uncoupling (CLOU)

“…Cu-based [2][3][4] and Mn-based materials mixed with Ca, Mg, Cu, Ni, Fe or Si [5] have focused great attention. Adánez et al [6] and Mattisson [7] summarize the oxygen carrier developed for CLOU and the facilities where have been tested. However, the proof of the concept of CLOU process burning coal in a continuous unit has been only demonstrated with a Cu-based oxygen carrier [8].…”

“…On the other hand, reaction rate also depends on the oxygen concentration in Eq. (7). Different values for the activation energy were obtained either Eq.…”

Examination of Perovskite Structure CaMnO3-δwith MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas

“…[27] showing that such oxides had CLOU capability and rapid oxidation rate at 850 ∘ C. Jing et al [28] have studied the Mn-Si combined oxide system and CLOU behavior; high methane and syngas conversion were reported. Rydén et al [29] provided an overview of six combined manganese oxides systems which have been studied so far with respect to CLOU, and Mattisson has provided a general overview of CLOU materials [30].…”

Reduction kinetics analysis of sol–gel-derived CuO/CuAl2O4 oxygen carrier for chemical looping with oxygen uncoupling

“…Obviously, the reaction order j in Eq. (2) is no longer zero during the oxygen release in the fluidized bed reactor. Assuming a first-order [28] dependence on p O 2 [32], the OC reduction rate has been analyzed by the following general form:…”

“…Chemical looping with oxygen uncoupling (CLOU) is a novel and attractive technology that allows the combustion of fossil fuels with inherent CO 2 separation [1,2]. It utilizes a special oxygen carrier (OC) which is able to decompose to a reduced metal oxide and gas-phase oxygen in the fuel reactor (FR) and regenerate in the air reactor (AR).…”