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

Abstract

Chemical looping with oxygen uncoupling (CLOU) is a promising technology due to its potential to reduce energy efficiency penalty and cost associated with CO2 capture. In this work, a CuO/CuAl2O4 oxygen carrier (OC) prepared by sol–gel was investigated in its oxygen release kinetics (4CuO → 2Cu2O + O2). Based on several well-organized temperature-programmed reduction experiments which were conducted in a thermogravimetric analyzer, the activation energy E (343.7 kJ mol−1) and pre-exponential factor A (3.78 × 1012 s−1) were determined and the Avrami–Erofeev random nucleation and subsequence growth model fitted well with the reduction experimental data. The enhancement of OC reduction rate in real fluidized bed CLOU reactor using different types of solid fuels (petroleum coke, anthracite, bituminous, and lignite) was identified in terms of the chemical kinetics and thermodynamics for the first time. It was found that the CuO reduction rate is more sensitive to the local temperature change than the oxygen concentration driving force. The results could contribute to the design, operation, and performance prediction of real CLOU reactors.