Enhanced coal tar-resistance of LaFeO3-based oxygen carrier for chemical looping reforming of coke oven gas

Chemical looping reforming of coke oven gas (COG) is a promising technology for producing cheap hydrogen, but the presence of coal tar with relatively high concentration presents an enormous challenge for the design of oxygen carriers. In the present work, the effect of naphthalene (a coal tar model compound) on the activity and structure stability of LaFeO 3 -based perovskite oxygen carriers for chemical looping reforming of COG were investigated. We found that the presence of naphthalene would inhibit the methane conversion and lead to serious carbon deposit on oxygen carriers, thus reducing the structure stability during the redox cycling. In response to the aforementioned findings, a series of La 1-x Y x Fe 0.93 Ni 0.07 O 3-λ perovskite oxygen carriers were designed based on co-doping of A and B sites strategy. The presence of Ni 2+ at B-site can improve the capacity of oxygen carrier for methane activation, and the Y 3+ substitution at A-site may enhance the activity of lattice oxygen via regulating the Fe-O bond-length. With a suitable content of Ni and Y, the La 0.9 Y 0.1 Fe 0.93 Ni 0.07 O 3-λ oxygen carrier shows superior performance for chemical looping reforming of COG, with the CH 4 conversion higher than 99% and excellent stability during long-term redox cycles in the presence of 400 ppm naphthalene at 800 °C. This work may provide a viable strategy for developing robust perovskite oxygen carriers for the chemical looping reforming of fuels with relativity high content of impurities. The synergy between the Y 3+ at A-site and Ni 2+ at B-site of LaFeO 3 significantly improves the coal tar resistance of oxygen carriers through mechanisms such as inhibiting carbon deposition and stabilizing the structure, which allows La 0.9 Y 0.1 Fe 0.93 Ni 0.07 O 3-λ to demonstrate excellent performance over 50 cycles. • The presence of coal tar reduces the structure stability of the oxygen carrier in CLSR. • Y doping enhances the tar-resistance of the LaFe 0.93 Ni 0.07 O 3-λ oxygen carrier. • The activity of lattice oxygen may be improved by weaking the Fe-O bonds. • The La 0.9 Y 0.1 Fe 0.93 Ni 0.07 O 3-λ also shows promising carbon deposit resistance.