THE DEVELOPMENT OF A NOVEL Cu-Mn OXYGEN CARRIER FOR THE CHEMICAL LOOPING GASIFICATION OF BIOMASS

摘要

Circulating fluidized bed technology applied to combustion processes in which oxygen and fuel are fed into separate reactors is referred to as Chemical Looping Combustion. Typically, oxygen reacts with a reduced metal (-oxide), then it is transferred to a second vessel where the metal oxide is reduced by a hydrocarbon. In chemical looping gasification, a fuel is contacted indirectly by oxygen and/or steam again with a metal oxide shuttling between two vessels reducing the contact between fuel and air. In this case, a concentrated stream of syngas exits the fuel reactor undiluted by nitrogen. The objective of this study is to develop a solids substrate capable of releasing oxygen in the fuel reactor. A bimetallic Cu-Mn oxygen carrier was synthesized by incipient wetness impregnation at ambient conditions over Al_2O_3. Copper-based oxygen carriers have superior oxygen transfer capacity and environmental and economical characteristics compared to nickel, iron and cobalt, but the operating temperatures are limited due to the low melting point of the metallic copper. Adding manganese to copper minimizes the formation of copper aluminate. Moreover, it inhibits copper agglomeration and carbon deposition. The developed oxygen carriers were characterized by BET, XRD and SEM analyzers. Also, oxygen transfer capacities of particles were tested using thermo gravimetric analysis (TGA). Results indicate that Cu-Mn is a superior carrier, which is suitable for the separation of oxygen in a chemical looping process. Also, adding manganese to copper allows working at high temperatures and improves the reactivity of copper.