Behavior of CaO/CuO Based Composite in a Combined Calcium and Copper Chemical Looping Process

Integration of chemical looping combustion into calcium looping is an attractive approach to solving the problem of energy requirement for the regeneration of CaO-based sorbent. In this work, the behavior of MgO supported CaO/CuO composite in the new combined process (CaCuCL) was investigated. The composite was prepared via a simple wet mixing method and measured via a thermogravimetric analyzer for its chemical performance. It appears that the component of Cu/CuO has a significant influence on the cyclic performance of CaO, which is probably caused by the “wrapping” of Cu/CuO outside, due to its low melting point. However, this negative effect can be greatly reduced by using appropriate operating conditions in the successive reactions. When tested for 68 cycles, all synthetic sorbents showed good reactivity and stability of the Cu/CuO component, although loss-in-capacity of CaO was stilled observed

Fabrication of CaO-Based Sorbents for CO₂ Capture by a Mixing Method

Three types of sorbent were fabricated using various calcium and support precursors via a simple mixing method, in order to develop highly effective, durable, and cheap CaO-based sorbents suitable for CO₂ capture. The sorption performance and morphology of the sorbents were measured in a thermogravimetric analyzer and a scanning electron microscopy, respectively. The experimental results indicate that cement is a promising low-cost support precursor for contributing to the enhancement of cyclic CO₂ sorption capacity, especially when organometallic calcium precursors were used. A sorbent (with 75% CaO content) made from calcium l-lactate hydrate and cement showed the highest CO₂ sorption capacity of 0.36 g of CO₂/g of sorbent and its capacity decreased only slightly after 70 cycles of carbonation and calcination

High-Temperature Pressure Swing Adsorption Process for CO₂ Separation

This paper presents a novel pressure swing adsorption process and the development of specifically designed sorbents for the process. It is operated at high temperature (650–800 °C) using the reversible reaction of calcium oxide with CO₂, i.e., CaO + CO₂ ⇄ CaCO₃. The new process directly stores the reaction heat released from the forward reaction in the sorbent and then releases it for sorbent regeneration under reduced CO₂ partial pressure, so that the need of pure oxygen for oxy-fuel combustion is avoided. Two potential problems of the new process, namely, loss in capacity and slow and unmatched reaction rates of chemical-controlled carbonation and calcination, were discussed in detail. Three specifically designed calcium-based sorbents showed stable performance during 92 isothermal carbonation–calcination cycles at either 680 or 750 °C. The calcination rate was significantly enhanced by increasing the reaction temperature and the introduction of steam to match the reaction rate of chemical-controlled carbonation. This pressure swing adsorption process could be used for low-cost CO₂ separation using specifically designed sorbents under carefully selected operating conditions

Recycling Spent LiFePO₄ Battery to Prepare Low-Cost Li₄SiO₄ Sorbents for High-Temperature CO₂ Capture

Renewable energy and electric vehicles are well-acknowledged strategies for reducing CO2 emissions, and their development relies heavily on the core of energy storage systems using lithium-ion batteries. However, recycling of lithium-ion batteries is far from mature, and massive abandonment of spent batteries would lead to severe environmental pollution. Meanwhile, the shortage of lithium resources brought about by the rapid development of lithium-ion batteries, especially LiFePO4, significantly drives up the preparation cost of Li4SiO4 as a promise sorbent and greatly limits its application as a CO2 capture scheme. Hence, a strategy is urgently needed to alleviate the lithium resource contradiction between energy storage and CO2 mitigation. Herein, we report a novel concept in recycling spent LiFePO4 battery to prepare high-efficiency and low-cost Li4SiO4 sorbents for CO2 capture. The obtained Li4SiO4 sorbents demonstrate very stable CO2 capacities of 0.27–0.28 g/g in a typical test up to 80 cycles, a leading level in CO2 capture, while the cost is only 1/6 of the conventional preparation process. It suggests that the concept of recycling spent LiFePO4 for CO2 capture has broad implications on resource utilization of energy waste and the mitigation of CO2 emissions

Theoretical Study on CO₂ Absorption from Biogas by Membrane Contactors: Effect of Operating Parameters

Biogas upgrading and utilization is a novel technology to obtain resource-efficient vehicle fuel. In this study, a mass transfer model for CO₂ absorption from biogas into potassium argininate (PA) solutions was developed. The computational fluid dynamics (CFD) methods were employed to solve the differential equations in three domains of the membrane contactor. The simulations were focused on the characteristics of both gas and absorbent phases to demonstrate the concentration distributions in axial and radial directions in the module. The simulated results were in excellent agreement with experimental data when considering the effect of initial CO₂ concentration and gas velocity. Furthermore, the effect of operating pressure, flow pattern, flow condition, and modules in series on the membrane performance was investigated. The results showed the purity of CH₄ reached 95% with the operating pressure of 0.9 MPa. It was found that a fluid in the turbulent condition or counter-current configuration had a significant effect on improving the contactor performance. The simulation results also indicated that the use of two modules could increase CO₂ removal and obtain high CH₄ purity. Finally, the results confirmed that the developed 2D model was able to predict the behavior of CO₂ separation in the membrane contactors