encapsulated liquid sorbents for carbon dioxide capture - carbon dioxide absorbent

by:Demi     2019-09-06
encapsulated liquid sorbents for carbon dioxide capture  -  carbon dioxide absorbent
The shortcomings of current CO2 capture methods include corrosion, evaporation loss and dirt.
The separation of capture solvents from infrastructure and exhaust gas by capsule provides possible solutions to these problems.
Here we report materials that may make low carbon captureCost and energy
Capture carbon dioxide efficiently from flue gas.
A polymer microcapsule consisting of a liquid carbonated core and a highly permeable silicone shell was prepared by a microfluid assembly method.
This pattern combines the capacity and selectivity of liquid adsorption agents with a high surface area to facilitate rapid and controlled CO2 absorption and release in repeated cycles.
Although the mass transfer on the capsule shell is slightly lower relative to the neat liquid adsorption agent, the surface area enhancement obtained through the package provides an orderof-
For a given quality of the adsorption agent, the magnitude of the rate of absorption of carbon dioxide increases.
The capsule is stable under typical industrial operating conditions and can be used for large-scale-
Carbon capture scale.
A pair of capsules is used.
A capillary device consisting of an external square glass capillary, an internal circular capillary polished by flame, and a final circular capillary pulled to a fine tip.
Pull the pulled-out tip to a final diameter of 30-40 μm using a laser puller.
Insert two circular capillary tubes into the square glass capillary tube.
Epoxy is used to glue the tip of the syringe to the capillary and seal the device to the slide.
Double emulsion droplets produced by co-
Three kinds of fluid flowing in the device :(1)
Aqueous solution of carbonate (inner fluid)
For carbon capture solvents ,(2)
A kind of hydrophobic optical polymerization silica gel (middle fluid)(
Semicosil 949UV, Wacker Chemical Company)
For Shell material and (3)
Water-carrying fluid containing surface active substances (outer fluid).
After formation, the droplets leave the device, collect in the liquid and solidify under ultraviolet light (=365u2009nm).
After curing, the aggregated capsules can be transferred.
After manufacture, the capsule is stored in a potassium carbonate solution that is infiltrated with the liquid absorbent core to minimize infiltration expansion and rupture ().
When the infiltration gradient is minimized, the capsule is stable for many years without significant changes in size or leakage.
Before packaging, the introduction of the pH-indicated dye thymol blue into the carbonated solvent can visually confirm the absorption of CO's encapsulated carbonated molecules, thus causing pH swing.
When the carbonated solution absorbs CO, it reacts to form a bicarbonate based on the following conditions: when the carbonated ion acts as a buffer: Until CO is absorbed, the dissolved carbon is "undeposited" at the initial"
In contrast, after CO absorption, carbon exists in the form of bicarbonate, resulting in a decrease in pH and doubling the initial carbon content in a complete "loade" solution.
The calculated pH value of the liquid adsorption core as the CO absorption function and the corresponding thy phenol blue color transformation are provided in.
A custom test equipment has been established to control and quickly cycle capsules between different gases and temperatures.
In a single cycle, the capsule is first exposed to nitrogen in a wet flow (N)
Gas at 40 °c to achieve temperature balance.
Next, they are exposed to CO gas for loading at 40 °c (CO absorption).
Finally, they are exposed to N gas for unloading at 100 °c (
CO resolution).
80 cycles were repeated.
For the boiling bed test, the capsule is first removed from the storage solution, allowing for a short drying in the air, and then lightly powdered with potassium carbonate dust.
The capsule is then loaded in an improved graded cylinder, the mesh blocks the inlet and outlet and is connected to the N and CO gas sources to flow at a surface speed of 1.
Two kinds of gas, 6 u2009 m u2009 s.
When N is used for proof-of-concept testing at room temperature, industrial processes may regenerate at high temperatures using a mixture of CO or CO and steam as a streamer.
Adsorption line (
Balance capacity)
A new solid adsorption agent is usually reported.
However, the vapor-liquid equilibrium of carbonated solutions has been previously studied, and the MECS process is not expected to change the equivalent vapor-liquid equilibrium of the packaged solvent.
In contrast, encapsulation may strongly influence absorption dynamics.
Therefore, we focus on measuring the absorption rate at the associated CO pressure.
To measure CO absorption dynamics, we suspended the MECS on a sealed fixed steel mesh
Temperature-volume
Controlled vacuum chamber equipped with pressure gauge and valve introducing CO ().
Although the weight analysis method is usually used in the study of solid adsorption agents, the water exchange inside and outside the mixed liquid solid capsule system we are studying here makes this technology complicated.
The mesh size is selected to separate the capsules from each other and to maximize the accessible surface area.
The chamber was evacuated to the steam pressure of the solution, introducing a controlled amount of CO, then sealing the chamber and monitoring the total pressure over time.
Assume that the water vapor pressure remains the same and subtract from the total amount to give the CO split pressure.
Typical raw data for this absorption measurement are shown.
As shown in the figure, the absorption dynamics and absorption capacity of the material can be measured as the difference between the slope of the pressure over time trajectory and the starting and final CO differential pressure, respectively.
For the control experiment, we created a small pool in the equipment with a depth of 1mm, which is the average depth of the solution on the packaging in the typical packaging tower for CO capture.
Low load (high pH)
, Stirring or flow has little effect on the CO absorption rate of carbonated solution because the rate is driven by the reaction.
Therefore, the 1 u2009 mm pool is a reasonable representation of the absorption rate of a typical tower.
Since the encapsulated liquid adsorption agents and pools have the same composition, it is possible to make a meaningful comparison of their CO absorption kinetics.
To test the dynamics and capacity of the capsule in multiple absorption-regeneration cycles, we used the described sealing chamber and pressure measurements.
To regenerate the capsule after each exposure, we heated the capsule to 90 °c in wet air for 10 minutes.
Detailed information about the carbonate capacity, thermodynamics, and mass transfer models can be found in.
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