In-situ reforming and combustion of liquid fuel using MnOx/Ce-γAl2O3 oxygen carrier in a chemical looping combustion process

Abstract

A new MnOx/Ce-γAl2O3 oxygen carrier is developed for liquid fuel based fluidized chemical looping combustion (CLC) process. The developed material serves both as a catalyst and as a source of solid phase oxygen for gasification/reforming of liquid fuel followed by the combustion of the gasified products. The support γAl2O3 is modified with cerium, improved thermal stability and minimized the interaction with the main active component MnOx. In order to validate the desired properties, the prepared MnOx/Ce-γAl2O3 samples are characterized using various physicochemical characterizations, including X-ray fluorescence (XRF), nitrogen adsorption, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). TPR, TGA and XRD analysis confirm that the Ce modification improves the thermal stability of γAl2O3 and hinders the formation of difficult reducing manganese aluminate. TPR profiles show excellent reduction and re-oxidation performances of the Ce modified samples. Based on characterizations, a selected sample is further evaluated in a fluidized CREC Riser Simulator (CREC: Chemical Reactor Engineering Centre) using n-hexane as a liquid fuel surrogate. Under the studied reaction conditions (500–650 C; 10–45 s reaction time), CO2 and CO are the main combustion products. At 650 °C, approximately 92% n-hexane combustion and 60% of CO2 selectivity was achieved, which is very encouraging, given the complexity of the interaction of liquid fuel with the solid metal oxides.