A viable way to manage the inherently intermittent availability of solar energy in concentrated solar power plants is to store solar energy during on-sun hours to be able to use it later during off-sun hours, enabling on-demand electricity delivery. Thermochemical heat storage systems present some noteworthy advantages when compared with latent and sensible heat storage, namely (i) high energy storage density because the storage capacity by unit of mass or volume corresponding to the reaction enthalpy is generally high, (ii) heat storage at room temperature and long term energy storage because the products can be cooled and stored at room temperature without energy losses as heat can be stored indefinitely in chemical bonds, (iii) facility of transport because solid materials can be transferred over long distances, (iv) constant restitution temperature providing constant heat source because exothermic reactions are carried out at sufficiently high temperatures to generate electricity in constant conditions and therefore to produce a constant power. This paper presents an overview of the different potential thermochemical systems based on reversible solid-gas reactions operating at high temperatures and a screening of suitable materials that are interesting candidates in the 400–1200 °C range for thermochemical heat storage in concentrated solar power systems. The most promising materials belonging to the metal oxides, hydroxides, and carbonates solid-gas systems are selected for experimental validation and further investigations.

Screening of thermochemical systems based on solid-gas reversible reactions for high temperature solar thermal energy storage

Adsorption of arsenic, phosphorus and chromium by bismuth impregnated biochar: Adsorption mechanism and depleted adsorbent utilization

CO2 adsorption on a fine activated carbon in a sound assisted fluidized bed: Thermodynamics and kinetics

An investigation of CO2 adsorption kinetics on porous magnesium oxide

Biochar, a product of pyrolysis of biomass, represents an attractive alternative to non-renewable or unsustainably sourced biomass as an adsorbent material for treating gaseous effluents. Biomass from residues associated with agricultural and forestry operation, otherwise considered waste material or a storage issues, represents a potential sustainable source of adsorbent. There are several adsorbents for removal of contaminants from gases including carbon based, silica based, and metal oxide based adsorbents; however, availability of feedstock, low cost, and potential high adsorption capacity distinguish biochar from other adsorbents. This review includes common sorbents for removal of contaminants from gas, biochar production methods, and compares biochar with activated carbon as one of the most common commercial adsorbents. Adsorption isotherms, mechanisms, and process systems for removal of acid gases such as CO2 and H2S by biochars have been comprehensively reviewed. The application of molecular modeling to describe adsorption by activated carbons and possible extension to biochar were studied. There is still a lack of published information in the molecular modeling of biochars, and using these models to understand the complex adsorbent mechanisms on the very heterogeneous surfaces of biochar (relative to commercial adsorbent materials such as activated carbons). Therefore, further research needs to fill these gaps to identify all potentials of this promising adsorbent.

A review on common adsorbents for acid gases removal: Focus on biochar

In this work, highly porous MgO was synthesized for CO2 adsorption by a simple and economic thermal decomposition of basic magnesium carbonate and magnesium oxalate. Characterizations of the synthesized samples were accomplished using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and nitrogen adsorption–desorption isotherms. The results showed that the synthesized MgO possessed a high BET surface area in a range of 161–252 m2 g−1 and a highly porous structure. Thermo gravimetric analysis revealed that the synthesized MgO not only showed good selectivity to CO2 but also yielded a CO2 adsorption capacity of as high as 7.59 wt%. Besides, in situ FTIR spectroscopy and CO2 TPD curves demonstrated that the adsorption mechanism of synthesized MgO was mainly attributable to chemisorption and it could be regenerated at relatively low temperature. This work provides a new way to synthesize MgO with a highly porous structure for CO2 adsorption.

Synthesizing MgO with a high specific surface for carbon dioxide adsorption

Carbon dioxide adsorption characteristics of synthesized MgO with various porous structures achieved by varying calcination temperature

MgO is a promising candidate for CO2 capture. In general, MgO is prepared from different precursors, which have an important effect on its CO2 adsorption performance. Meanwhile, the effect of precursor on the porous structure and CO2 adsorption of MgO remains largely unknown. In this work, porous MgO was prepared from different precursors to investigate the effect of precursor source. Experimental results showed that the morphology of MgO was greatly influenced by that of the precursor and was similar to that of its precursor. Due to the emission of by-products during decomposition, MgO prepared from a precursor with a high molecular weight per single Mg atom exhibits a highly porous structure, large pore volume and pore size. The highly porous structure is favorable for the CO2 adsorption of MgO. The pores formed on the decomposition of precursor play an important role in CO2 adsorption performance, which is affected by the molecular weight per single Mg atom. Narrow pores of MgO from precursors with low molecular weights hinder CO2 diffusion and lead to a low CO2 capacity at fixed adsorption time. The results indicate that the adsorption performance of MgO could be enhanced through the regulation of precursor source and its morphology. This work provides a useful guidance for the synthesis of porous materials with high performance in CO2 capture.

Gan Song

Papers

An investigation of CO2 adsorption kinetics on porous magnesium oxide

Synthesizing MgO with a high specific surface for carbon dioxide adsorption

Carbon dioxide adsorption characteristics of synthesized MgO with various porous structures achieved by varying calcination temperature

Influence of the precursor on the porous structure and CO2 adsorption characteristics of MgO

Bench scale study of CO2 adsorption performance of MgO in the presence of water vapor