Highly Active CaO-Based Sorbents for CO2 Capture Using the Precipitation Method: Preparation and Characterization of the Sorbent Powder

Solution combustion synthesis of MgO-stabilized CaO sorbents using polyethylene glycol as fuel and dispersant

The main limit for the calcium looping process is the sharp decrease of the capture capacity of the CO2 sorbents during multiple cycles. In this research, a solution combustion method was employed to synthesize MgO-stabilized CaO sorbents. Polyethylene glycol (PEG) was used as the fuel and dispersant, with the purpose to enhance the uniformity of the Ca and Mg distributions in the sorbent. The results show that highly reactive MgO-stabilized CaO sorbents can be obtained through a solution combustion method using PEG as the fuel and dispersant. The existence of MgO can effectively restrain the sintering of the sorbent, resulting in a more porous and stable micro-structure of the sorbent. The CO2 capture capacity of the MgO-stabilized CaO sorbent synthesized under the optimum conditions is 0.40 g(CO2)/g(sorbent) after 20 cycles, which is 75.3% higher than CaCO3.

Post-combustion CO2 capture via a variety of temperature ranges and material adsorption process: A review

Carbon dioxide (CO₂) emissions from fossil fuel combustion have been linked to increased average global temperatures, a global challenge for many decades. Mitigating CO₂ concentration in the atmosphere is a priority for the protection of the environment. This is a comparison of the three main technological categories available for CO₂ capture and storage. They include: oxy-fuel combustion, pre-combustion, and post-combustion. Each capture technology has inherent benefits and disadvantages in cost, implementation, and flexibility, but post-combustion CO₂ capture has demonstrated the most promising results in typical power plant configurations. This paper presents a review of different post-combustion CO₂ capture materials; solvents, membranes, and adsorbents, focusing on economical and environmentally safe low to high temperature solid adsorbents. Furthermore, the authors summarize the advantages and limitations of the materials investigated to provide insight into the challenges and opportunities currently facing the development of post-combustion CO₂ capture technologies. The solid sorbents currently available for CO₂ capture are also reviewed in detail, including physical and chemical properties, reactions, and current research efforts on improvement.

Synthesis and Formation Mechanism of Limestone-Derived Porous Rod Hierarchical Ca-based Metal-Organic Framework for Efficient CO2 Capture

Limestone is a relatively abundant and low-cost material used for producing calcium oxide as a CO₂ adsorbent. However, the CO₂ capture capacity of limestone decreases rapidly after multiple carbonation/calcination cycles. To improve the CO₂ capture performance, we developed a process using limestone to transform the material into a rod Ca-based metal-organic framework (Ca-MOF) via a hydrothermal process with the assistance of acetic acid and terephthalic acid (H₂BDC). The structural formation of rod Ca-MOF may result from the (200) face-oriented attachment growth of Ca-MOF sheets. Upon heat treatment, a highly stable porous rod network with a calcined Ca-MOF-O structure was generated with a pore distribution of 50-100 nm, which allowed the rapid diffusion of CO₂ into the interior of the sorbent and enhanced the CO₂ capture capacity with high multiple carbonation-calcination cycle stability compared to limestone alone at the intermediate temperature of 450 °C. The CO₂ capture capacity of the calcined porous Ca-MOF-O network reached 52 wt% with a CO₂ capture stability of 80% after 10 cycles. The above results demonstrated that rod Ca-MOF can be synthesized from a limestone precursor to form a porous network structure as a CO₂ capture sorbent to improve CO₂ capture performance at an intermediate temperature, thus suggesting its potential in environmental applications.

Interactions of acylated methylglucoside derivatives with CO2: simulation and calculations

Carbohydrates have drawn considerable interest from researchers recently due to their affinity for CO2. However, most of the research in this field has focused on peracetylated derivatives. Compared with acetylated carbohydrates, which have already been studied in depth, methyl D-glucopyranoside derivatives are more stable and could have additional applications. Thus, in the present work, ab initio calculations were performed to elucidate the characteristics of the interactions of methylglucoside derivatives with CO2, and to investigate how the binding energy (ΔE) is affected by isomerization or the introduction of various acyl groups. Four methyl D-glucopyranosides (each with two anomers) bearing acetyl, propionyl, butyryl, and isobutyryl moieties, respectively, were designed as substrates, and the 1:1 complexes of a CO2 molecule with each of these sugar substrates were modeled. The results indicate that ΔE is mainly influenced by interaction distance and the number of negatively charged donors or interacting pairs in the complex; the structure of the acyl group present in the substrate is a secondary influence. Except in the case of methyl 2-O-acetyl-D-glucopyranose, the ΔE values of the α- and β-anomers of each methylglucoside were found to be almost the same. Therefore, we would expect the CO2 affinities of the four derivatives studied here to be as strong as or even stronger than that of peracetylated D-glucopyranose. Graphical Abstract The binding energy between methyl D-glucopyranoside derivatives with various substituted acyl groups and CO2 are evaluated by ab initio calculations. The strong interaction between these methyl dglucopyranoside derivatives and CO2 showed the potential of their application for CO2 capture.

Influence of the operation conditions on CO2 capture by CaO-derived sorbents prepared from synthetic CaCO3

In this work, a statistical experimental design is performed in order to prepare CaCO3 materials for use as CaO-based CO2 sorbent precursors. The influence of different operational parameters such as synthesis temperature (ST), stirring rate (SR) and surfactant percent (SP) on CO2 capture is studied by applying Response Surface Methodology (RSM). The samples were characterized using different analytical techniques including X-ray diffraction, N2 adsorption isotherm analysis and Scanning Electron Microscopy-X-ray Energy Dispersive Spectroscopy (SEM-EDX). CO2 capture capacity was determined by means of a thermogravimetric analyzer which recorded the mass uptake of the samples when these were exposed to a gas stream containing diluted (15%) CO2. The statistical approach used in this work provides a rapid way of predicting and optimizing the main preparation variables of CaO-derived sorbents for CO2 sorption. The results obtained clearly indicate that four parameters statistically influence CO2 uptake: SR, the square of SR, its interaction with SP and the square of SP.