Natural Gas Combustion Characteristics in a Chemical-Looping Combustor with Three Different Oxygen Carrier Particles

Abstract

Natural gas combustion characteristics of oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor (0.05 m ID, 0.6 m high). Three particles, NiO/bentonite, NiO/NiAl₂O₄, and Co_xO_y/CoAl₂O₄, were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. All three oxygen carrier particles showed high gas conversion, high CO₂ selectivity, and low CO concentration during reduction and no NO_x (NO, NO₂, N₂O) emissions during oxidation. Moreover, all three particles showed good regeneration ability during successive reduction–oxidation cyclic tests up to the 10th cycle. The gas conversion, CO₂ selectivity and CO concentration were maintained to 97% of initial values for all three particles. These results indicate that inherent CO₂ separation, NO_x-free combustion, and long-term operation without reactivity decay of oxygen carrier particles are possible in the natural gas fueled chemical-looping combustion system with NiO/beotonite, NiO/NiAl₂O₄ and Co_xO_y/CoAl₂O₄ particles.