Converting Co2 to Co : Two-Step Chemical Looping Dry Reforming Using a Composite Cafe-Zrce Oxygen Carriers

Chemical Looping Dry Reforming (CLDR) using oxygen carrier (OC) is a novel technology to convert CO 2 to CO. Currently, Ca 2 Fe 2 O 5 (CF) OC is found to be a potential material for CLDR. In this paper, Zr 0.5 Ce 0.5 O 2 (ZC) was used to improve the reduction rate of CF OC and alleviate the sintering. The reaction performance of modified OCs in CLDR were explored in a thermogravimetric analyzer and a fixed bed reactor, and the fresh and reacted OCs were characterized by an XRD and a TEM. The results show that CF6 (60wt%CF+40wt%ZC) has the best reduction activity. During CO 2 oxidation, the CO yield increases from 72.3 mL/g to 138 mL/g using CF6 as an OC. Since Fe and CaO can be oxidized to CF by CO 2 through a one-step reaction, the reduced Fe is directly oxidized to Fe 3+ by CO 2 , which omits the step of air oxidation. XRD shows that a new phase of CaZrO 3 , inhibited the redox reaction was formed in CF6 after 20 cycles. In addition, with the increase of the cycle numbers, the particle size of the sample gradually increases through the TEM analysis, which indicates that the sintering of OC sample occurred. Therefore, the CO yield from CO 2 oxidation shows a decrease trend with cycles, which decreases from 138 mL/g at 1 st cycle to 34.3 mL/g at the 5 th cycle and then tends to stable in the following 15 cycles. After 20 cycles, the extension of reduction time of OC facilitates the generation of CO, the CO yield increase from 35 mL/g to 60 mL/g when the reduction time is doubled. Although the cyclic performance decreases, the reactivity of CF6 OC is still better than that of CF OC, whose CO yield is about 20% lower than that of CF6