Molecular Layer Deposition of Amine-Functional Groups on Fumed Silica Nanoparticles for CO2 Capture

Creating a Solid Adsorbent Material for Direct Air Capture

Hailey Loehde-Woolard – University of Colorado Boulder


Traditional liquid CO2 capture techniques have relied on the chemical reaction between the acidic CO2 and a basic absorbent, usually liquid amines such as monoethanolamine. However, more recently, solid adsorbent materials have received much attention due to the high regenerative energy requirements and physical limitations of liquid systems. Popular materials have included zeolites, metal organic frameworks (MOFs), microporous organic polymers (MOPs), and supported amines. Current processes of loading the amines have focused on impregnation (physical mixture of support and amine-containing compound) and grafting (bonding amine-containing compounds to the surface, usually through wet reactions). However, sorbents made through impregnation face poor regeneration stability and transport limitations; while grafted sorbents tend to have low adsorption capacities. Here, Particle Molecular Layer Deposition (MLD) is used as a loading method to improve the regeneration stability and adsorption capacity of supported amine sorbents.


0:00:02   Hello, everyone. I'm Hayley and we'll be talking to you today about CIA to capture with the meat
0:00:07   observance and the technique of molecular layer deposition to function alliances, materials. So
0:00:12   let's jump right in. The rate of anthropogenic carbon emission has surpassed the rate of natural
0:00:17   carbon position. We have accumulated over 400 ppm. See if you in our atmosphere along with other
0:00:22   greenhouse gasses, we've already reached a global mean warming of about one degree Celsius from pre
0:00:27   industrial levels. According to the 2018 i. P. C. C. Report, we're likely to see about a 1.5 degree
0:00:33   warming between 2030 and 2052 now. This increases the climate related risks for the natural and
0:00:39   human systems. Such a sea level rise will also habitat and more frequent severe weather events. Now,
0:00:45   in order to stay out or below the 1.5 degrees Celsius mark, we must reduce global neck anthropogenic
0:00:50   commissions at 45% by 2030 and reach net zero by 2050 now. We simply cannot do this by decreasing
0:00:58   emissions alone. So we must capture the release, see a to some methods of carbon capture, focus on
0:01:04   point sources or where the emissions were generated. This includes pre combustion and post
0:01:09   combustion methods that will cover many of the major station. Your producers, like power plants,
0:01:13   however captured from these sources is incomplete and does not account for random sources such as
0:01:18   vehicles, most of businesses or land use change and therefore it's imperative that we developed
0:01:23   technology for the direct heir capture of Sio two. Now direct air capture presents a myriad of
0:01:29   challenges. This includes huge processing volumes of air variability of relative humidity and
0:01:35   ambient temperature. Low Co. Two concentrations in the air and the operation costs for all of this.
0:01:41   Not to address these challenges. We need an adult material that's inherently scalable, performs
0:01:47   under a wide range of absorption conditions, is inexpensive to make him use and has a high
0:01:52   selectivity for C or to perform at low concentrations. Now together in these attributes will make
0:01:57   direct air capture. A simple process is actually feasible to implement. Now we're actually no
0:02:03   strangers describing CO two from gashes streams. Since the 19 thirties, you've been using liquid
0:02:07   amines such as model ethanol amine in industry to remove Seok cover these liquid amines and other
0:02:13   liquid basis require a lot of energy to regenerate their very caustic. And it can damage equipment
0:02:18   over time, not to mention the environmental concern upon disposal. To address these limitations, the
0:02:25   field of Salt Co. Two absorbent materials has grown over the last few decades. Many materials have
0:02:30   been investigated, including, but not limited to Z lights, metal, organic frameworks and micro
0:02:35   porous organic polymers. Many of these have focused on bluegrass operations as they were lying on
0:02:41   busy absorption and the higher C two concentration. Many of these materials also have issues with
0:02:46   humidity. Is water will keep the exercise, however supported a mean absorbent, have set the
0:02:53   precedent for direct air capture. They're currently implemented by commercial companies with his
0:02:58   Golden Pharma stat and climb works Now supported. It means combined some advantages of both the
0:03:02   traditional liquids and solids orbits that means their basic. And so, too, is the Lewis acid, the
0:03:08   acid. This reaction and provides selective Kennedy's option for the CO two Now, as you can see, the
0:03:13   schematics, both primary and secondary means can react with the CO two to form charged species. Now,
0:03:19   depending upon the functional groups and the surface coverage, it could create a few different in
0:03:22   sort of species. But nevertheless this is a stronger bond and more selective than the other. Solids
0:03:27   or materials, like the lights that rely on disease options and further water does not directly
0:03:32   inhibit the absorption of CO two, instead provides an alternative reaction. Foreign ammonium and a
0:03:38   bicarbonate ion pair. Now, furthermore, means they're widely regarded to absorb under ambient
0:03:45   temperatures and pressures, and have relatively low these option temperature under 120 degrees
0:03:50   Celsius. So it's really no wonder that amine functional materials have set the precedent for co two
0:03:55   capture indirect air capture in particular. Now, a variety of support there used their usually very
0:04:00   high surface area, and there are too many techniques of function izing. This materials impregnation
0:04:06   involves making physical mixture of the support and you need, and what grafting involves binding the
0:04:10   news to the surface through liquid reactions. However, impregnation results in poor regeneration,
0:04:16   stability and transport limitations, and the Grafton's often solvent intensive and can lead to some
0:04:21   lower fortune capacities. Now, to address these issues, we propose particle molecular layer
0:04:27   deposition are MLD now. MLD is closely related to atomic layer deposition, but it deposits larger
0:04:33   molecules that are option organic Now. Both processes rely on alternating and self women and gas
0:04:38   phase reactions, and these reactions result in a functional film film that's conveniently bound to
0:04:43   the surface now, by nature of the gas tanks reactions, we can use a minimal amount of precursor, and
0:04:48   there's no other seldom required. So we believe that MLB functional ization will create a low cost
0:04:55   immune absorbent with stable regeneration and high its origin. But for these specific materials, I'm
0:05:02   using teams. Silicon nanoparticles is my support. There are only a couple dollars for a kilogram,
0:05:07   and you can scale a powder however you need. And it has a high surface area of around 318 years
0:05:12   squared program, and it's already covered in hydroxyl groups on the surface that feed right into the
0:05:17   deposition chemistry for the NLD itself. I'm using a family about Cox C. Silence that are referred
0:05:23   to is the mono Di and Tri Means from here on out, and the reactions alternate between the precursor
0:05:29   and water at 150 degrees Celsius and a vibrating food. I spent reactor like the lunch on previous
0:05:34   slide. Now to confirm and quantify the deposition. We've done leeco nitrogen analysis now. This
0:05:42   showed increasing nitrogen content as a number of MLT cycles increased, which is what we would have
0:05:46   expected from performing additional cycles and further. The absorption capacity was measured through
0:05:51   thermo gravimetric analysis and should competitive in Munich. Efficiencies now keep in mind with
0:05:56   maximum and inefficiencies one half because to our fingers there needed trapped with the single co
0:06:01   two model.
0:06:04   Also through through a gravimetric analysis, we tested the regeneration stability that melding
0:06:08   materials with a representative computer. No absorption is at 30 degrees Celsius and these options
0:06:14   at 80 and it appears stable over the 25 cycles that we performed on. We also believe that the desert
0:06:19   don't be stable below the NLD temperature of 150 degrees Celsius, and finally, this table shows have
0:06:27   a preliminary NLD observance. Compared to the other supportive means in larger as a surgeon is
0:06:33   inherently a surface reaction. It's important to maximize the functionality of available surface
0:06:38   area when the absorption capacities standardized based on the surface area of the support instead of
0:06:43   weight are NLD absorbent directly compares actually outperforms many of these materials. So in terms
0:06:49   of making use of the available surface area, MLD appears to functional. Is the surface very well
0:06:54   making a successful method for C or to adore in preparation and further our materials right and
0:06:59   expected range for absorption and disruption temperature as well as a demonstrated with generation
0:07:04   ability.
0:07:06   So, in conclusion here, we've introduced the novel use of particle MLD on team silicon nanoparticles
0:07:12   to create supportive and you deserve materials for co two capture. Furthermore, we demonstrated the
0:07:17   performance of these preliminary materials that show competitive immune efficiency and surface
0:07:21   functionality as well as regeneration ability in terms of the dressings, uh, in terms of addressing
0:07:30   the servant requirements established earlier, thes MLD absorbent are inherently scalable in low cost.
0:07:36   We also demonstrated absorption near Indian temperatures and standard pressure.
0:07:43   The future work with these materials will involve optimizing the number of MLD cycles and studying
0:07:47   the fundamental thermodynamics and kinetics of the absorption toe. Understand the effects of
0:07:52   humidity and atmospheric C two concentrations on the absorption performance of these materials. On
0:07:57   with that, I'd like to thank my advisor, Professor Alan Weimer, as well as the rest of the Weimer
0:08:03   lab. Thank you for listening to the stock