Low-energy-consumption temperature swing system for CO_(2) capture by combining passive radiative cooling and solar heating

Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.

Solid amine sorbents for CO_(2) capture by chemical adsorption: A review

Amines are well-known for their reversible reactions with CO_(2),which make them ideal for CO_(2) capture from several gas streams,including flue gas.In this respect,selective CO_(2) absorption by aqueous alkanolamines is the most mature technology but the process is energy intensive and has also corrosion problems.Both disadvantages can be diminished to a certain extent by chemical adsorption of CO_(2) selectively.The most important element of the chemical adsorption of CO_(2) involves the design and development of a suitable adsorbent which consist of a porous support onto which an amine is attached or immobilized.Such an adsorbent is often called as solid amine sorbent.This review covers solid amine-based studies which are developed and published in recent years.First,the review examines several different types of porous support materials,namely,three mesoporous silica(MCM-41,SBA-15 and KIT-6)and two polymeric supports(PMMA and PS)for CO_(2) adsorption.Emphasis is given to the synthesis,modifications and characterizations-such as BET and PXRD data-of them.Amination of these supports to obtain a solid amine sorbent through impregnation or grafting is reviewed comparatively.Focus is given to the adsorption mechanisms,material characteristics,and synthesis methods which are discussed in detail.Significant amount of original data are also presented which makes this review unique.Finally,relevant CO_(2) adsorption(or equilibrium)capacity data,and cyclic adsorption/desorption performance and stability of important classes of solid amine sorbents are critically reviewed.These include severa PEI or TEPA impregnated adsorbents and APTES-grafted systems.

Effect of acoustic field on C02 desorption in a fluidized bed of fine activated carbon

Adsorption using solid sorbents has the potential to complement or replace current absorption technol- ogy, because of its low energy requirements. Among the commercially available adsorbent materials, attention is focused on activated carbons because they are easily regenerable by reason of their low heat of adsorption. These sorbents are generally available in the form of fine powders. Sound-assisted fluidization can process large amounts of fine powders, promoting and enhancing CO2 capture on fine sorbents, because it maximizes gas-solid contact. Temperature swing adsorption （TSA）, consisting of inducing sor- bent regeneration and CO2 recovery by appropriate temperature increase and gas purge, is one of the most promising techniques. This study investigates the CO2 desorption process by TSA in a sound-assisted flu- idized bed of fine activated carbon. Desorption tests were performed under ordinary and sound-assisted fluidization conditions to assess the capability of sound to promote and enhance the desorption efficiency in terms of CO2 recovery, CO2 purity, and desorption time. The results show that the application of sound results in higher desorption rates, CO2 recovery and purity. Regular and stable desorption profiles can be obtained under sound-assisted fluidization conditions. This stability makes it possible to successfully realize a cyclic adsorption/desorption process.

Greenhouses for CO_(2) sequestration from atmosphere

Escalating threat of global warming and the steady growth in world population require the development of transformative greenhouse gas control technologies and food production systems of high energy efficiency,small environmental footprint and low cost.To control the global temperature rise below 2℃ by 2050,global greenhouse gas emissions need to be cut by more than 80%.At the same time,our land needs to be utilized more efficiently and productively in order to produce enough food to feed projected 9 billion people with less available land area for food production in 2050.We propose to develop a modern urban vertical farming system,i.e.greenhouses equipped with a Carbon Enrichment for Plant Stimulation(CEPS)system,to enhance land use efficiency and thus increase food productivity and,at the same time,to sequestrate CO_(2) from ambient air.The deployment of such a CEPS system will have a potential to remove more than 500 million tonnes CO_(2) from air annually,and increase the current food productivity by more than 15 times than the open field operation.The deployment of the CEPS technology will also promote locally produced food,benefiting urban economical development and job creation.

Thermodynamic analysis on direct air capture for building air condition system:Balance between adsorbent and refrigerant

Direct air capture(DAC)is one of the most potential technologies to mitigate CO_(2) emission.Adsorption technol-ogy is recognized as a promising CO_(2) capture method in view of its desirable characteristics including reusability of adsorbents and low capital investment.To further improve thermal performance,evaporation/condensation heat of vapor compression refrigeration(VCR)cycle in air condition system of buildings is adopted for adsorp-tion/desorption process of DAC.Thermal performance of a 4-step temperature swing adsorption process(TSA)is analyzed at various adsorption/desorption temperatures by using different adsorbents.Analysis on Coefficient of Performance(COP)of VCR cycle is also conducted in search for a balance between adsorbent and refrigerant.Taking both real working capacity and COP into consideration,Mg-MOF-74&R134a is the best choice for more amounts of CO_(2).Real working capacity of Mg-MOF-74 is up to 0.38 mol•kg−1 at 70°C,which is twice as much as that of zeolite 13X.While zeolite 13X&R134a shows the best performance of two cycles in view of exergy efficiency and COP,which could reach 81.9%and 7.21,respectively,at 35°C.These matches will provide some guidelines for the practical application of the combination of DAC with heating,ventilation and air conditioning(HVAC).