Experimental study on composite oxygen carrier NiFe2O4/Sr4Fe6O13 in chemical looping reforming coupled with thermochemical water splitting

In this study, a series of composite oxygen carriers (OCs) of NiFe 2 O 4 /Sr 4 Fe 6 O 13 (xNiySr 4 ) was synthesized by solid-phase synthesis method. The performance evaluation for syngas and hydrogen production was investigated in chemical looping reforming coupled with thermochemical water splitting using ethanol as fuel. The presence of NiFe 2 O 4 enhanced the lattice oxygen activity and intensified the reduction of Sr 4 Fe 6 O 13 . The Ni–Fe alloy was produced in fuel reactor (FR) and then promoted water splitting in steam reactor (SR) for hydrogen production. The presence of Sr 4 Fe 6 O 13 regulated the reactivity of NiFe 2 O 4 , which prevented the ethanol complete oxidation in FR and enhanced the syngas production. Additionally, the introduction of Sr 4 Fe 6 O 13 decreased the content of NiFe 2 O 4 and suppressed carbon deposition, which resulted in a high purity of hydrogen in SR. Moreover, the existence of Sr 4 Fe 6 O 13 mitigated the sintering of NiFe 2 O 4 . The composite oxygen carrier of NiFe 2 O 4 /Sr 4 Fe 6 O 13 exhibited better cyclic stability than the single NiFe 2 O 4 and Sr 4 Fe 6 O 13 oxygen carrier. The 0.4NiFe 2 O 4 /0.6Sr 4 Fe 6 O 13 oxygen carrier, termed as 4Ni6Sr 4 , exhibited a good performance for syngas and hydrogen production performance at 800 °C. A high syngas purity of 74.36% was observed with a yield of 1.05 Nm³/kg ethanol in FR. The hydrogen yield and purity in SR were 6.51 mmol/g OC and 96.60%, respectively.