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Chemical looping with O2 uncoupling aims at using an oxygen carrier (OC) with O2 uncoupling behaviour to promote fuel conversion. Natural ilmenite ores have been considered highly promising OCs for chemical looping technology; however, they do not possess any O2 uncoupling behaviour. Mn‐modified ilmenite ores as OCs are capable of O2 uncoupling, while most of them are synthesized via complicated procedures by using costly chemicals. In this study, a strategy of calcination treatment on ilmenite ores mixed with manganese ores has been established to introduce Mn into the ilmenite OCs, endowing them with O2 uncoupling behaviour in a simple and low‐cost manner. The O2 uncoupling behaviour from Mn‐modified ilmenite ores is mainly due to the newly formed (Fe1−xMnx)2O3/(Fe1−xMnx)3O4 crystal phases generated during the calcination treatment, which also alleviate the thermodynamic limit of the Mn2O3‐Mn3O4 redox pair. As a result, the Mn‐modified ilmenite ore OCs can release O2 at high temperatures when decreasing the oxygen partial pressure. But more importantly, the reduced OCs can be restored in the air isothermally. This established simple calcination treatment method can be used as a low‐cost strategy for producing ilmenite‐based OCs with O2 uncoupling behaviour. The O2 uncoupling behaviour is expected to be beneficial to chemical looping combustion of fuels, promote fuel conversion, minimize OC loading, and reduce energy consumption. [ABSTRACT FROM AUTHOR]

The high contents of Ni, Co, and Mn in the retired cathode of ternary lithium-ion battery (rCTLIB) make it a promising raw precursor for preparing value-added reactive materials. However, most strategies for valorizing the rCTLIB highly depend on chemical leaching of Ni, Co, and Mn through complex procedures that involve the use of harsh liquids. Valorizing the rCTLIB through simple physical pathways is highly promising. Chemical looping combustion (CLC) is an innovative technology for producing energy from fossil fuels while inherently separating the resulting CO 2 into a nearly pure stream for subsequent permanent storage or utilization. In this study, high-performance oxygen carrier (OC) materials for the CLC of syngas have been successfully synthesized using a facile and scalable method that physically pelletizes the rCTLIB with Al 2 O 3 binder. Performance tests show that the H 2 and CO conversions in CLC of syngas exceed 90% for all prepared OCs. This performance is comparable to that of popularly employed OCs based on supported oxides. Moreover, the obtained OCs physically prepared from the rCTLIB demonstrate high stability with respect to reactivity and oxygen transport capacity, indicating a high potential for valorizing the rCTLIB into high-performance materials for applications involving CO 2 capture. [Display omitted] • A new strategy towards the valorization of retired cathode has been established. • High-performance oxygen carrier is synthesized non-chemically from retired cathode. • The oxygen carrier has been used for the chemical looping combustion of syngas. • Introducing Al 2 O 3 binder and pre-cycling Li improves the cyclic stability. • The optimized oxygen carrier exhibits syngas conversion over 90%. [ABSTRACT FROM AUTHOR]

Chemical looping reforming of CH 4 (CH 4 -CLR) is an advanced technology for syngas generation, and ilmenite ore has been considered a promising oxygen carrier material due to its extremely low cost. However, the weak reactivity of ilmenite ore over CH 4 prevents its practical application in CH 4 -CLR. This study has established a facile strategy to enhance the reactivity of CH 4 toward ilmenite ore by simply introducing the same but reduced ilmenite ore as the catalyst for a pre-activation of CH 4 , so as to accelerate the reaction between the CH 4 and ilmenite. Results show that the addition of reduced ilmenite ore as catalyst significantly accelerates the reaction between CH 4 and ilmenite ore, which successfully reduces the induction period from 150 min to almost 0 min. A higher catalyst to oxygen carrier ratio, higher temperature and deeper reduction stage of the catalyst are all beneficial in accelerating the reaction between CH 4 and ilmenite ore. [Display omitted] • A significantly accelerated syngas production for chemical looping CH 4 reforming. • Ilmenite ore functions as both oxygen carrier and catalyst. • The catalyst of reduced ilmenite shortens the induction period from 150 min to 0. [ABSTRACT FROM AUTHOR]

• Fe 2 O 3 /Al 2 O 3 pellets have been used as both the oxygen carrier and the catalyst. • Chemical looping CH 4 reforming has coupled with dry CH 4 reforming. • The co-conversion of CH 4 and CO 2 to syngas has been achieved in a single reactor. • The new reaction system provides an opportunity for CO 2 utilization. Chemical looping reforming of CH 4 (CH 4 -CLR) is a safe and efficient CH 4 upgrading technology for syngas production. The Fe 2 O 3 -based oxygen carriers (OCs) possess a higher potential for CH 4 -CLR among so many transition metal oxides as high syngas selectivity can be obtained from partial CH 4 oxidation by OCs with the step-by-step reduction of Fe3+/Fe2+ to Fe0. However, the impurity CO 2 in CH 4 -source feed gas, when using Fe 2 O 3 -based OCs, often causes the inhibition of reaction between CH 4 and OCs resulting in no partial CH 4 oxidation to syngas. The present work has employed the Fe 2 O 3 /Al 2 O 3 pellets as OCs with introducing the fully reduced same pellets as a catalyst in a bubbling fluidized-bed reactor to eliminate the inhibition effect of CO 2 during CH 4 -CLR. It has been demonstrated that the Fe species with low valent, e. g., Fe0, in the catalyst can effectively catalyze the dry CH 4 reforming. Thus, the CO 2 has been consumed before contacting with Fe 2 O 3 -based OCs and the inhibition effect of CO 2 has been eliminated. Meanwhile, both CO 2 and CH 4 can be converted to syngas in the reducer leading to an opportunity for CO 2 utilization. With the help of the catalyst of reduced OCs, not only the CO 2 in the feed gas but also that formed from full CH 4 oxidation by Fe 2 O 3 /Al 2 O 3 at the early CH 4 reforming stage is converted into syngas of CO and H 2. Semi-continuous cyclic CH 4 -CLR test has demonstrated the good stability of both Fe 2 O 3 /Al 2 O 3 OC and counterpart catalyst, which suggests the potential of such OC/catalyst pair in practical applications. [ABSTRACT FROM AUTHOR]

• Oxygen carriers (OCs) promote the conversion of fuel N to NO in the rotary kiln. • Fuels in the passive layer can obtain O 2 or lattice oxygen from OCs. • OCs promote the oxidation of S-containing compounds into SO 2. • Manganese and ilmenite ores promote the release of Cl as HCl at high temperatures. Rotary kiln incineration technology has become an important approach to achieve the harmless, reduced, and resourceful solid waste (SW) due to its wide range of fuel adaptability and high treatment efficiency. SW incineration through oxygen carrier (OC) aided combustion in the rotary kiln shows significant advantages in improving SW conversion and reducing CO emission. However, the impacts of introducing OC into the rotary kiln on the emissions of NO, SO 2 , and HCl, are still unknown. This research objective was to investigate the effects of OCs on the emission characteristics of NO, SO 2 , and HCl. Natural manganese and ilmenite ores as OCs, are added to a continuous-feeding rotary kiln during the combustion of biomass SW and hazardous SW. The results show that the introduction of OCs can significantly improve the uniformity of oxygen distribution in the furnace, and promotes the conversion of fuel N to NO. At high temperatures and low oxygen concentrations range, the reduction rate of NO by high-concentration CO or catalytic reduction by char and ash is faster than the oxidation of fuel N by OCs, which decreases NO concentration. Moreover, at high temperatures, when OCs are distributed in the bed of the rotary kiln, the fuel in the oxygen-poor zone can obtain O 2 or lattice oxygen from the OCs, which promotes the decomposition and oxidation of S-containing compounds in fuels and increase the SO 2 concentration. In addition, OCs in the bed provide more reaction sites for fuel conversion and promote the release of Cl as HCl at high temperatures. Specifically, during the oil sludge combustion at 900 °C, compared with the inert reference case, the addition of ilmenite ore increased the concentrations of NO, SO 2 , and HCl by 47.44%, 64.87%, and 20.28%, respectively, which is attributed to the better reactivity and redox cycle stability of ilmenite ore. This study highlights the potential of OC-aided combustion in rotary kilns as an approach to regulate SW combustion and offers a foundation for the future related research. [ABSTRACT FROM AUTHOR]