Name: Preparation of Wet Grafted Silica with N&#8217;-(3-Trimethylsilyl Propyl) Diethyleneamine (DAS)
Uploaded: 2023-09-29T14:40:00
Description: Watch this Scientific Journal Video about Preparation of Wet Grafted Silica with N'-3-Trimethylsilyl Propyl Diethyleneamine DAS at JoVE.com

preparation of wet grafted silica with n’-(3-trimethylsilyl propyl) diethyleneamine (das)

Imprægnering og podning af aminerede forbindelser på silicasubstrater

The anthropogenic CO2 emissions over the past several decades have been widely implicated as the main factor driving the greenhouse gas effect and consequently, related climate change1,2,3,4. There are two general methods for CO2 capture, point source and direct air capture. For more than 50 years, wet-scrubbing CO2 capture technologies have been utilized for point source capture within the industry to mitigate CO2 emissions5,6. These technologies are based on liquid-phase amines that react with CO2 to form carbamates under dry conditions and hydrogen carbonates in the presence of water7,8, see Figure 1. The main reason that carbon capture and storage is utilized at large point (industrial) sources is to prevent the further release of large quantities of CO2, thus having a neutral effect on total CO2 concentration in the atmosphere. However, point-source carbon capture systems suffer from several drawbacks, such as equipment corrosion, solvent degradation, and high energy requirements for regeneration9. Direct air capture (DAC) goes beyond emission reduction and can facilitate the removal of CO2 from the atmosphere. The removal of this existing CO2 is necessary to limit continued climate change. DAC is an emerging methodology and must address the difficulties of removing low concentrations of CO2 in atmospheric conditions (400 to 420 ppm), operate in a variety of different environmental conditions, and address the need for cost-effective materials that can be reused many times1,2,3. Significant work is needed to identify materials that meet these requirements, which will accelerate the adoption of DAC and improve its economic feasibility. Most importantly, community consensus on critical parameters of measurement needs to be established, which is essential for benchmark materials to be developed.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65845/65845fig01.jpg" /> 
Figure 1: Schematic of the expected liquid amine adsorbent CO2 capture mechanism. The top reaction is in dry conditions, and the bottom reaction is in the presence of moisture. <a href="https://www.jove.com/files/ftp_upload/65845/65845fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In an effort to remedy these drawbacks, considerable research and development of novel porous material technology have resulted in a wide array of promising materials that have the potential to be utilized as either capture materials or substrates for DAC. Some examples of such materials include mesoporous silica species10,11,12,13, zeolites14,15, activated carbon16,17, and metal-organic frameworks18. Many solid-supported amine adsorbents also show a higher tolerance to water, which is a vital consideration in CO2 removal through DAC approaches. For DAC applications, researchers must consider wet/dry environmental conditions, hot/cold temperatures, and an overall dilute atmospheric CO2 concentration. Amongst the various substrate materials, silica is commonly used because of its adjustable pore sizes, ability to surface functionalize, and large surface area1,2,3. Typical synthetic procedures and primary features of both impregnated and grafted amine-silica composites are described within this work (Figure 2). Direct synthesis, where the material is made in situ with both components, substrate and amine, is another commonly used methodology2.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/65845/65845fig02.jpg" /> 
Figure 2: Schematic representations of impregnation. Mixing of PEI and silica substrate in methanol through diffusion (top) and grafted amine-silica composites through covalent tethering (bottom). <a href="https://www.jove.com/files/ftp_upload/65845/65845fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Impregnation&#160;is a method in which an amine is physically adsorbed onto a surface, in this case, a porous silica medium, through van der Waals forces and hydrogen bonding between the amine and silica surface19,&#160;see Figure 2. Solvents such as ethanol and methanol are commonly used to promote the diffusion of the molecules into the porous structure of the substrate material. The solution can also be heated to increase the solubility of the high molar mass polyamines, thereby increasing the homogeneity of amine penetration within the pores. In the case of impregnated materials, the amount of amine introduced to a silica substrate is determined by the initial quantity of the amine and the surface area of the substrate. If the amount of amine introduced exceeds the available surface area of the silica substrate, the amine species will agglomerate on its surface. This agglomeration is readily apparent, as the impregnated material will appear to have a gel-like coating, often yellow, rather than the expected white and powdery appearance1. Among the many types of amine-base solid adsorbents, polyethyleneimine (PEI) and tetraethylene pentamine (TEPA) are the most widely used due to their high stability and high nitrogen content20. For physically impregnated systems, the theoretical loading quantity of amine can be calculated from the pre-weighted amounts of the substrate and the density of the amine. The obvious advantage of physical impregnation lies in the straightforward synthesis procedure to prepare it, as well as the potential for a large amine content due to the high porosity of the silica substrate. Conversely, the stability of the amine within the silica is limited because there is no covalent bonding between the amine and silica support. Therefore, after multiple cycles of CO2 uptake and regeneration through heat or steam, the amine can leach out of the pores. Despite these drawbacks, the implementation of such materials for DAC holds great promise for removing CO2 from the atmosphere.
Another option for the preparation of DAC materials is grafting. Grafting is a method through which amines are immobilized onto a porous silica substrate through a chemical reaction, as shown in Figure 2. This reaction proceeds by reacting an aminosilane with the surface&#39;s silanol functional group, resulting in a covalent bond. Therefore, the number of functional groups on the surface of the silica substrate impacts the grafted amine density21,22. Compared to amine-impregnated adsorbents, chemical grafting methods have had lower CO2 adsorption capacity mainly due to the low amine loading21. Conversely, chemically-grafted amines have increased thermal stability due to their covalently bound structure. This stability can be useful in the regeneration of the material as adsorbents (such as grafted silica) are heated and pressurized to remove the captured CO2 for reuse to save material and cost. In a typical synthesis procedure, the mesoporous silica substrate is dispersed in a solvent (e.g., anhydrous toluene), which is then followed by the addition of aminosilanes. The resulting sample is then washed to remove unreacted aminosilanes. Improvements in aminosilane density are reported to have been achieved through water addition, specifically with SBA-15, to expand pore size23. The procedure for grafting that will be described herein uses moisture-sensitive techniques. Therefore, additional water will not be used. Implementation of grafted aminosilane materials for DAC is promising due to their expected stability during CO2 adsorption and desorption processes. However, the major drawbacks of this methodology include the complex reactions/preparation of these materials, leading to increased cost, and their overall low CO2 adsorption capacity, meaning larger quantities are required.
Overall, results of many previous studies indicate that the structure of the substrate and amine-related modification has a significant impact on the adsorption performance with specific studies utilizing techniques such as transmission electron microscopy (TEM) and quasi-elastic neutron scattering (QENS) to fully characterize these materials24,25. In other words, the structural properties (e.g., porosity and surface area) of the substrate material determine the amine loading, so increasing these parameters can improve CO2 capacity24,25. Continued research into the optimization and design of substrate materials and preparation processes is critical to the development of high-performance adsorbents for DAC. The goal of this work is to provide guidance on impregnation and grafted amine synthesis in hopes of facilitating better transparency of synthetic techniques. Within the literature, specific details on the amounts of solvent, substrate, and amines are not always described, making it difficult to understand the correlation between experimental loading amounts and quantitative measurements of amine-silica composites. The exact loading amounts and a detailed description of the experimental procedures will be provided herein to better facilitate these types of comparisons.

Forfatter Spotlight: Standardisering af udviklingen af aminbaserede silicakompositter som CO2-adsorbenter til direkte luftopsamling 

En syntetisk metode til fremstilling af imprægnerede og podede aminbaserede silicakompositter til kulstofopsamling

Scientists here at NIST are developing critical measurement science and benchmark materials to accelerate innovation and explore timely, effective, and scalable direct air capture, or DAC, for carbon-dioxide removal from the atmosphere. This work focuses on promoting best practices for preparation, measurement, and reporting of amine-functionalized silica composites for DAC applications. This protocol addresses outstanding research challenges and reproducible synthetic procedures for DAC materials by providing clear guidelines and conditions while identifying critical steps.In addition, we aim to enable a meaningful comparison of carbon-dioxide capabilities of these materials through clear documentation of specific adsorption experimental parameters. We are turning our efforts towards characterizing benchmark materials and developing standard techniques to foster greater comparability and confidence in reported results.

Watch this Scientific Journal Video about Preparation of Wet Grafted Silica with N'-3-Trimethylsilyl Propyl Diethyleneamine DAS at JoVE.com

Preparation of Wet Grafted Silica with N&#8217;-(3-Trimethylsilyl Propyl) Diethyleneamine (DAS)  

Fremstilling af vådpodet silica med N'-(3-trimethylsilylpropyl)diethylenamin (DAS)

For at begynde tørre alt glasvarer i ovnen i mindst to timer før brug. For at sikre en fugtfri overflade. Opbevar aminosilan DAS i en lågflaske med septumkappe.Overvej den passende DAS-belastning for at øge sandsynligheden for aminosilanen. Lokalisering af silanolgrupperne på silica til kovalent binding. Tilsæt den ønskede mængde silicastøtte i en rundbundet Schlenk-kolbe udstyret med en magnetisk omrøringsstang.Og indsæt en gummiseptum i reaktionsbeholderen, før du fjerner luft og fugt fra beholderen, der er forbundet med Schlenk-linjen. Åbn først reaktionsbeholderens stophane for at forbinde den til vakuumet i ca. 30 sekunder. Luk derefter stophanen, skift til en inert gasforsyning i yderligere 30 sekunder.Indsæt en linje inaktiv gas i lågflasken med septumlåg, der indeholder vandfri toluen. Brug en gastæt sprøjte til at trække den ønskede mængde toluen og rens sprøjten med inaktiv gas. Før opløsningsmidlet fjernes fra flasken, skal du sikre dig, at den magnetiske omrøring inde i reaktionsbeholderen omrøres jævnt, og punktere septum på reaktionsbeholderen med den gastætte sprøjte, der indeholder den vandfrie toluen, og overføre toluen til beholderen.Når den inaktive gasnål er fjernet fra toluen, skal nålehovedet ændres. Derefter overføres den ønskede mængde DAS som tidligere demonstreret til reaktionsbeholderen. Brug en adapter til at fastgøre en linje fra Schlenk-apparatet til en vandkondensator ved hjælp af vakuumfedt.Pak bunden af kondensatorapparatet ind med polytetrafluorethylen eller PTFE-tape, og fastgør en septum til bunden af kondensatoren. Efter at have udsat ledningen for vakuum og inert gascyklus tre gange, fastgøres kondensatorapparatet til den runde bund Schlenk-kolbe. Fastgør derefter koldtvandsledningerne til vandkondensatoren, og tænd for vandcirkulationen.Sænk reaktionsbeholderen ned i et silikoneoliebad ved en temperatur på 80 til 100 grader Celsius. Stophanen lukkes for den inaktive gas på den rundbundede Schlenkkolbe, og stophanen på kondensatoren står åben. Rør reaktionen under opvarmning i seks timer.Derefter afkøles reaktionsbeholderen til stuetemperatur. Tilslut derefter Erlenmeyer-kolben til vakuumet via en slange. Placer en gummispuns ved åbningen, før du placerer en Buchner-tragt oven på gummispunsen.Efter anbringelse af et filter i Buchner-tragten vådes filteret med vandfri toluen. Tænd for vakuumet, før opløsningen hurtigt fordeles på filteret for at opsamle den faste podede aminsilica på filterpapir. Skyl det opsamlede materiale tre gange med ca. 10 ml vandfri toluen.Brug en ren, tør laboratoriespatel til at overføre det hvide podede silanmateriale fra filterpapiret til et hætteglas. Når hætteglasset er dækket med punkteret aluminiumsfolie, skal du placere det i en vakuumovn og tænde for støvsugeren. Indstil ovnen til ca. 100 grader Celsius.Og lad det tørre i ca. 18 timer for at fjerne overskydende toluen.

Research

JoVE Journal

Chemistry

Preparation of Wet Grafted Silica with N’-(3-Trimethylsilyl Propyl) Diethyleneamine (DAS)

A Synthetic Methodology for Preparing Impregnated and Grafted Amine-Based Silica Composites for Carbon Capture

Recently, there has been a significant effort towards reducing or mitigating CO2 emissions through the use of carbon capture materials for point source or ...