Solid sorbents with enhanced capacity and selectivity towards CO2 are crucial in the design of an efficient capture process.Among the possible alternatives,K2CO3-doped activated carbons have shown high CO2 capture cap...Solid sorbents with enhanced capacity and selectivity towards CO2 are crucial in the design of an efficient capture process.Among the possible alternatives,K2CO3-doped activated carbons have shown high CO2 capture capacity and rapid carbonation reaction rate.In this work,a sustainable and low-cost approach is developed with a biomass-based activated carbon or biocarbon as support.The CO2 capture performance in cyclic sorption–desorption operation and the sorption kinetics have been investigated under different scenarios in a purpose-built fixed-bed set-up.Independent of the H2O concentration in the flue gas,a constant relative humidity(~20%)in the K2CO3-doped biocarbon bed promoted the carbonation reaction and boosted the CO2 sorption capacity(1.92 mmol/g at 50℃ and 14 kPa partial pressure of CO2).Carbonation is slower than physical adsorption of CO2 but wise process design could tune the operation conditions and balance capture capacity and sorption kinetics.展开更多
Carbon nanotubes-based materials have been identified as promising sorbents for efficient CO_(2)capture in fluidized beds,suffering from insufficient contact with CO_(2)for the high-level CO_(2)capture capacity.This s...Carbon nanotubes-based materials have been identified as promising sorbents for efficient CO_(2)capture in fluidized beds,suffering from insufficient contact with CO_(2)for the high-level CO_(2)capture capacity.This study focuses on promoting the fluidizability of hard-to-fluidize pure and synthesized silica-coated amine-functionalized carbon nanotubes.The novel synthesized sorbent presents a superior sorption capacity of about 25 times higher than pure carbon nanotubes during 5 consecutive adsorption/regeneration cycles.The low-cost fluidizable-SiO_(2)nanoparticles are used as assistant material to improve the fluidity of carbon nanotubes-based sorbents.Results reveal that a minimum amount of 7.5 and 5 wt%SiO_(2)nanoparticles are required to achieve an agglomerate particulate fluidization behavior for pure and synthesized carbon nanotubes,respectively.Pure carbon nanotubes+7.5 wt%SiO_(2)and synthesized carbon nanotubes+5 wt%SiO_(2)indicates an agglomerate particulate fluidization characteristic,including the high-level bed expansion ratio,low minimum fluidization velocity(1.5 and 1.6 cm·s^(–1)),high Richardson−Zaki n index(5.2 and 5.3>5),and lowΠvalue(83.2 and 84.8<100,respectively).Chemical modification of carbon nanotubes causes not only enhanced CO_(2)uptake capacity but also decreases the required amount of silica additive to reach a homogeneous fluidization behavior for synthesized carbon nanotubes sorbent.展开更多
文摘Solid sorbents with enhanced capacity and selectivity towards CO2 are crucial in the design of an efficient capture process.Among the possible alternatives,K2CO3-doped activated carbons have shown high CO2 capture capacity and rapid carbonation reaction rate.In this work,a sustainable and low-cost approach is developed with a biomass-based activated carbon or biocarbon as support.The CO2 capture performance in cyclic sorption–desorption operation and the sorption kinetics have been investigated under different scenarios in a purpose-built fixed-bed set-up.Independent of the H2O concentration in the flue gas,a constant relative humidity(~20%)in the K2CO3-doped biocarbon bed promoted the carbonation reaction and boosted the CO2 sorption capacity(1.92 mmol/g at 50℃ and 14 kPa partial pressure of CO2).Carbonation is slower than physical adsorption of CO2 but wise process design could tune the operation conditions and balance capture capacity and sorption kinetics.
文摘Carbon nanotubes-based materials have been identified as promising sorbents for efficient CO_(2)capture in fluidized beds,suffering from insufficient contact with CO_(2)for the high-level CO_(2)capture capacity.This study focuses on promoting the fluidizability of hard-to-fluidize pure and synthesized silica-coated amine-functionalized carbon nanotubes.The novel synthesized sorbent presents a superior sorption capacity of about 25 times higher than pure carbon nanotubes during 5 consecutive adsorption/regeneration cycles.The low-cost fluidizable-SiO_(2)nanoparticles are used as assistant material to improve the fluidity of carbon nanotubes-based sorbents.Results reveal that a minimum amount of 7.5 and 5 wt%SiO_(2)nanoparticles are required to achieve an agglomerate particulate fluidization behavior for pure and synthesized carbon nanotubes,respectively.Pure carbon nanotubes+7.5 wt%SiO_(2)and synthesized carbon nanotubes+5 wt%SiO_(2)indicates an agglomerate particulate fluidization characteristic,including the high-level bed expansion ratio,low minimum fluidization velocity(1.5 and 1.6 cm·s^(–1)),high Richardson−Zaki n index(5.2 and 5.3>5),and lowΠvalue(83.2 and 84.8<100,respectively).Chemical modification of carbon nanotubes causes not only enhanced CO_(2)uptake capacity but also decreases the required amount of silica additive to reach a homogeneous fluidization behavior for synthesized carbon nanotubes sorbent.
