Highly Cyclic Stability and Absorbent Activity of Carbide Slag Doped with MgO and ZnO for Thermochemical Energy Storage

Abstract

Carbide slag is a solid waste with a high content of reactive CaO, which can be used as an active material for the chemical absorption of CO2 and calcium looping. Calcium looping of CaO-based absorbents is one of the most promising methods of thermochemical energy storage. However, the sintering of pores and a reduction in the CO2 diffusion rates as the carbonization/calcination cyclic reaction progresses have posed challenges to the practical application of CaO-based absorbents. This study proposes a method for alleviating the sintering of the pore structure by improving the activity and cycling stability of such absorbents by doping carbide slag with MgO and ZnO powders. Results showed that the raw material ratio, reaction temperature, and reaction time have a considerable influence on the CO2 absorption rate. Furthermore, the specific surface area and pore volume of the absorbents increased with increasing ZnO and MgO doping levels in the carbide slag. Thus, the problems of sintering and clogging of pores in CaO-based absorbents were effectively alleviated, and the MgO and ZnO-doped absorbents CMZ85 and CMZ90 maintained 41–42% CO2 absorption after 10 cycles. These results confirmed that the cyclic stability and absorbent activity improved significantly with the MgO and ZnO doping of carbide slag for the calcium looping process.

A Dual Modification Method to Prepare Carbide Slag into Highly Active CaO-Based Solar Energy Storage Materials

“…Previous experiments have explored the effects of the reaction temperature and reaction atmosphere on the carbonation conversion rate in carbonation reactions. The experiments have shown that when the reaction is carried out under 650 °C and pure CO 2 conditions, the carbonation conversion rate of composite materials is the highest . In addition to the carbonization temperature and atmosphere, the carbonization reaction time also affects the energy storage performance of the carbide slag materials.…”

Influence of Long-Term CaO Storage Conditions on the Calcium Looping Thermochemical Reactivity

“…Sensible heat stored accounts for around 40% of the high-temperature storage scheme (Figure 8b). (9) where X is the conversion, ΔH R is the reaction enthalpy (GJ/ kmol), c p,i is the specific heat of component i (MJ/kmol•K), T reactor is the decomposition reaction temperature (K), T i,vessel is the storage temperature of component I (K), υ i is the specific volume of component i at storage conditions (m 3 /kmol), ε i is the internal porosity of component i, and ϕ is the particle packing density, whose value is set to 0.6 as a standard value for the random loose packing fraction of irregularly shaped particles under gravity.…”

“…The use of CaL as a mid to high-temperature carbon capture and storage technology is currently at the technology readiness level (TRL) 7. , As a TCES system, CaL displays several advantages, such as high energy density, nontoxicity, and the wide availability and affordability of the potential raw materials, which include Ca-containing minerals, rocks, and even industrial wastes. ,− …”

Analysis of the Variable Influence and Energy Storage Performance in Preparation of Solar Energy Storage Materials via Modification of Carbide Slag Using MnO2 through Wet Doping

“…Calcium carbide slag is a type of industrial solid waste with Ca­(OH) 2 as its main component . Most industrially produced calcium carbide slag is discarded in landfills, which not only causes major environmental problems but also wastes resources. , Because calcium carbide slag contains a large amount of Ca­(OH) 2 , it is considered a promising CO 2 absorbent in calcium-cycling technology. Thermochemical energy storage CaL is based on the reversible carbonation/calcination reaction.…”