Charlotte M. Wentz 感谢通过 NIST 奖 # 70NANB8H165 获得的资金。Zois Tsinas 希望通过 NIST 奖 # 70NANB22H140 获得资助。

注意: 与本节中使用的设备、仪器和化学品相关的详细信息可在 材料表中找到。
1. 用摩尔质量为 800 g/mol 的聚乙烯亚胺浸渍二氧化硅 （PEI 800）
<ol><li>反应的制备<ol><li>在该反应中使用无水甲醇作为溶剂。它的沸点低;因此，它的挥发性有利于以后在较低温度下去除。 注:无水溶剂很重要，因为水可以防止PEI 800进入二氧化硅载体的孔隙。另一种常用的溶剂是乙醇，其沸点较高，需要更长的干燥时间和更高的干燥温度。</li>
		<li>使用公式 1 计算胺的质量分数 （%），其中 m 胺 =胺 的质量，m 二氧化硅 = 所用二氧化硅 的质量。 公式 1: <img alt="Equation 1" src="/files/ftp_upload/65845/65845eq01.jpg" style="margin: auto;"></li>
		<li>MCM-41 二氧化硅中胺（w胺）的质量分数为 59.9%（750 毫克胺和 500 毫克二氧化硅）。每 1 g 胺，使用 10 mL 无水甲醇。这样做是为了让整体混合物成为稀浆料。这些计算量将被归类为实验量（w amine_exp），并针对每种合成方法（例如，w amine_exp_imp（浸渍）和 w amine_exp_graft（嫁接））进一步分类。</li>
		<li>为确保所有玻璃器皿没有水分，请在使用前将它们放入 140 °C 的烤箱中至少 1 小时。</li>
	</ol></li>
	<li>二氧化硅载体的制备 注:MCM-41二氧化硅是该工艺中使用的固体基质。由于MCM-41是吸附剂二氧化硅，因此有望从大气中或制造过程中吸附水。<ol><li>干燥 MCM-41 二氧化硅，以确保没有水吸附到其孔隙中。将所需量的二氧化硅放入玻璃培养皿中，用刺破的铝箔覆盖，然后将其放入真空烘箱中。</li>
		<li>首先，施加真空（通常小于 3 kPa，根据每个单独的真空系统而变化），然后将烤箱设置为约 110 °C 的温度以确保除水。在进行合成之前，执行此步骤至少2小时。</li>
	</ol></li>
	<li>浸渍方法<ol><li>使用干净、干燥的实验室刮刀，将所需量（750mg）的聚乙烯亚胺（PEI）转移到反应容器中（在这种情况下，为35mL干燥小瓶）。运输时盖上反应容器的盖子。</li>
		<li>将反应容器转移到化学通风橱中，将其夹紧或固定在通风橱内，然后将其放在搅拌板上。取下反应容器的盖子。</li>
		<li>将干净、干燥的搅拌棒放入反应容器中。 注意:使用搅拌棒将确保均匀混合，可以使溶液搅拌更长时间，促进更好的分散，并且可以在不需要手动混合的情况下安全加热反应。</li>
		<li>使用移液管，从量筒中加入 7.5 mL 无水甲醇（每 1 g 胺使用 10 mL 甲醇）。打开搅拌板。让溶液混合15分钟，以确保PEI完全溶解并均匀分散在溶剂中。 注意:混合后，溶液将呈现清澈/透明，表示聚合物完全溶解。</li>
		<li>使用干净、干燥的实验室刮刀将所需量（500 mg）的预干燥二氧化硅（在本例中为 MCM-41）转移到称量纸上。将二氧化硅转移到通风橱内的反应容器中。 注意:该实验负载量的胺将与热重分析（TGA）的实际测量量相匹配。 注意:吸入二氧化硅粉尘会损害肺组织。建议在使用二氧化硅基材时佩戴 N95 呼吸器（有关个别实验室的适当选择，请参阅当地安全指南）并在化学排气罩中工作。这些二氧化硅材料通常表现出"静态粘附"特性，并且很容易分散在通风橱内。快速执行此步骤，以避免水分从空气中吸附到二氧化硅上。</li>
		<li>如果需要，添加额外的甲醇以将二氧化硅冲洗到容器中，以确保完全暴露于溶液中的PEI。混合物将以浆状形式出现;请参阅 图 3。</li>
		<li>将容器置于 40 °C 至 50 °C 的硅油浴、加热块或加热罩中，以确保 PEI 的完全溶解度、均匀混合，并促进胺负载到多孔二氧化硅中。 注意:在浸渍过程中并不总是使用高温，文献表明其他温度在室温 （RT）1,2,3 下混合。在该协议中，加热用于促进均匀混合。</li>
		<li>确保搅拌棒均匀混合溶液。让溶液在加热下搅拌约1小时。 注:根据反应大小和个人偏好，反应容器的选择可能会有所不同。因此，反应的加热方式（油浴、加热块或加热罩）可能会有所不同，以最好地适应反应容器的选择。</li>
		<li>将反应容器从热源中取出，使其冷却至室温，同时仍在搅拌。完全冷却后，停止搅拌并取下搅拌棒。</li>
		<li>将装有样品的容器置于舒伦克管路上的真空下（通常为 <3 kPa，缓慢降低压力以避免碰撞）。</li>
		<li>让反应容器保持在舒伦克管路上，直到所有溶剂明显去除。然后，将样品转移到不同的储存容器中，例如玻璃培养皿。</li>
		<li>然后将样品放入真空烘箱中，打开真空（通常为<1.3 kPa），然后将烘箱设置为约70°C。 让样品在真空下干燥至少18小时，以确保已除去足够量的甲醇。 注意:在将所选容器放入真空烘箱之前，请考虑溶剂的液位，因为样品和溶液可能会因真空而不规则地离开容器。通常，在将样品/容器放入真空烘箱之前，样品/容器中残留的溶剂不超过 1 mL。</li>
		<li>干燥后，物料呈白色粉末状。将其存放在无湿气、无空气的环境中，直到需要进一步使用。 注意: 此步骤可以在真空干燥器或手套箱中进行，该干燥器或手套箱是在无空气和无湿气的环境中制备的。有关预期的最终产品外观，请参见 图 4 。</li>
	</ol></li>
</ol><img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/65845/65845fig03.jpg"> 图3:反应的代表性图像。 （A） PEI 浸渍期间 PEI 二氧化硅浆料（在甲醇中）的照片，然后转移到加热块中，以及 （B） 加热 6 小时后 DAS 接枝装置完成。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig03large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/65845/65845fig04.jpg"> 图4:干燥后最终产品的代表性外观。 （A） PEI浸渍在wamine_exp_imp = 59.9 %。（B） 接枝 DAS 的 wamine_exp_das = 90.0 %。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig04large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
2.N'-（3-三甲基硅丙基）二乙烯胺（DAS）湿法接枝二氧化硅的制备
<ol><li>溶液的制备<ol><li>在该反应中使用无水甲苯。它具有高沸点（110°C），因此可以进行高温混合。氨基硅烷（N'-（3-三甲基硅丙基）二乙烯胺（DAS）在这种介质中极易溶解。 注:在无水条件下进行该反应很重要，因为水可以与氨基硅烷相互作用，从而改变其与二氧化硅表面键合的性质。使用的无水甲苯带有隔膜盖。因此，将使用气密注射器将溶剂转移到反应容器中。每 1 g DAS，使用 5 mL 甲苯。因此，对于 5 mL DAS （1.028 g/mL），使用 25 mL 溶剂。</li>
	</ol></li>
	<li>二氧化硅载体的制备<ol><li>使用上述步骤1.2中的程序干燥二氧化硅。</li>
	</ol></li>
	<li>硅氧烷的制备<ol><li>氨基硅烷对水分敏感，因为水的存在会导致聚合。因此，将反应作为无水分反应处理。将 DAS 储存在带隔盖的瓶中，并使用气密注射器进行转移。 注意:氨基硅烷存在许多健康风险和危害。在开始实验之前，请重新view 安全数据表，并遵守所有推荐的安全预防措施。</li>
	</ol></li>
	<li>接枝二氧化硅方法<ol><li>需要注意的是，与浸渍方法不同，氨基硅烷在二氧化硅基底上的接枝氮含量预计较低。因此，在该反应中，通过实验将 wamine_exp_graft = DAS 的 90.0% 负载量增加氨基硅烷在二氧化硅载体上定位硅醇基团并成功共价键合的概率。</li>
		<li>使用前在烤箱中干燥所有玻璃器皿至少 2 小时，以确保表面无潮。</li>
		<li>用所需量（500mg）的二氧化硅支持物（MCM-41）填充装有磁力搅拌棒的圆底舒伦克烧瓶。</li>
		<li>将橡胶隔膜插入反应容器中，并在舒伦克管路上循环反应容器三次，以去除空气和水分。为此，将反应容器的旋塞阀打开至真空约 30 秒，关闭旋塞阀，切换到惰性气体（N 2 或 Ar2）约 30 秒，然后重新打开旋塞阀。反应容器循环后，保持惰性气体环境以进行以下程序步骤。</li>
		<li>将一行惰性气体插入隔膜盖（确保密封）瓶中，然后使用气密注射器并用惰性气体吹扫注射器，然后除去所需量的无水甲苯（在这种情况下，25 mL）。 注: 有关带有惰性气体入口和气密注射器的密封容器的图像，请参见 图 5 。在转移之前将弯头（蓝色箭头）放入管中以防止任何滴落。这种技术适用于任何需要气密注射液体时。溶剂的用量由氨基硅烷的添加量决定。每1 mL氨基硅烷，使用5 mL无水甲苯，以保证溶解度。重要的是用 25 mL 甲苯填充注射器，然后将针头抬高到瓶内的溶液水平以上。然后从甲苯上方的顶部空间抽出一些惰性气体，然后再从甲苯容器中取出注射器。</li>
		<li>在开始此步骤之前，确保反应容器内的磁力搅拌棒搅拌平稳。通过刺穿反应容器上的隔膜并将甲苯释放到容器中，转移气密注射器中所含的无水甲苯。</li>
		<li>用惰性气体取下针头。</li>
		<li>用氨基硅烷（4.8mL DAS）重复相同的步骤（2.4.6至2.4.8）。</li>
		<li>使用适配器将舒伦克管线的管线连接到使用真空润滑脂的冷凝器。用聚四氟乙烯 （PTFE） 胶带包裹冷凝器设备的底部（此步骤确保不会被油脂污染）。然后将冷凝器装置连接到圆底舒伦克烧瓶上，以准备玻璃器皿设置;请参阅 图 3。</li>
		<li>将"冷"水管连接到冷凝器并打开它。 注意: "冷"水（低于 23 °C）将进入冷凝器底部，然后从顶部进入水槽。管子将被固定（用电线、扎带或钢制软管夹），以避免连接点漏水。</li>
		<li>将反应容器放入硅油浴或加热块中，或将其置于80°C至100°C之间的加热罩中。 选择此温度有助于促进氨基硅烷 （DAS） 的接枝、均匀混合并促进胺负载。</li>
		<li>关闭旋塞阀，关闭圆底舒伦克烧瓶上的惰性气体，并使冷凝器上的旋塞阀保持打开状态;参见 图 3B。 注意:执行此步骤是为了防止甲苯上升到靠近设备（舒伦克烧瓶侧臂）的管中，同时由于冷凝器顶部的入口而将反应保持在惰性气氛下;有关此设置，请参见 图 3 。</li>
		<li>确保搅拌棒均匀混合溶液。加热6小时时搅拌。</li>
		<li>使用真空过滤捕获滤纸上的固体接枝胺二氧化硅，并用大量无水甲苯冲洗（10 mL 冲洗 3 次）。</li>
		<li>要进行真空过滤，请为锥形过滤器烧瓶配备臂，以通过软管进行真空抽真空。在开口处放置一个橡胶塞，将 Buchner 漏斗放在橡胶塞的顶部，最后在 Buchner 漏斗中放置一张滤纸。用无水甲苯润湿滤纸。</li>
		<li>打开真空吸尘器，快速将溶液分配到滤纸上。它有助于在洗涤过程中将无水甲苯倒入滤纸上之前用无水甲苯冲洗反应容器。</li>
		<li>最终材料在滤纸上显示为白色。使用干净干燥的实验室刮刀从滤纸上去除接枝的硅烷材料，并将其放入小瓶中。</li>
		<li>用刺破的铝箔盖住小瓶，然后将其放入真空烘箱中。打开真空吸尘器。将烤箱设置为约100°C，并干燥约18小时以除去多余的甲苯。 注意: 材料干燥后呈白色粉末状，并储存在无湿气、无空气的环境中。这可以放在真空干燥器或手套箱中，该干燥器或手套箱是在无空气和无湿气的环境中制备的。最终产品外观见 图 4 。</li>
		<li>此过程再重复两次（总共 3 次，步骤 2.4.1 - 2.4.16）。</li>
	</ol></li>
</ol><img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/65845/65845fig05.jpg"> 图 5:密封容器的照片。 （A） 带有连接到惰性气体（N 2 或 Ar2）的针头的容器，以及 （B） 连接惰性气体并连接气密注射器的容器，带有"弯曲"针头（蓝色箭头），用于转移而不会泄漏。<a href="https://www.jove.com/files/ftp_upload/65845/65845fig05large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
3. TGA对二氧化硅复合材料的分析
注:与此测量相关的标准不确定度约为质量± 0.01±%，温度约为 1 °C。
<ol><li>利用仪器的 TGA 应用软件，去皮一个空锅。</li>
	<li>从样品装载区域取出去皮的平底锅，然后将样品添加到平底锅中。将标本放在烤盘中央，至少使用2mg，以确保质量损失的充分解决。将装有试样的平底锅放回装载区域。</li>
	<li>使用仪器软件，定制程序运行，首先在100%N2环境中在约50°C下平衡5分钟，气体流速为60 mL/min。然后将斜坡设置为2°C/min至5°C/min至1000°C。 标记循环的结束。这些测量值表示为 wamine_TGA，因为它们使用 TGA 评估材料中的真实胺含量。这进一步分类为每种合成方法（例如，w amine_TGA_imp（浸渍法）和wamine_TGA_graft（接枝法））。 注意:对于单个 TGA，流速的具体建议可能有所不同。在为单个实验选择合适的流速之前，请咨询制造商的规格。</li>
	<li>重复步骤 3.1-3.3 进行任何其他实验运行。</li>
	<li>将步骤3.1应用于CO2 吸附实验设置。</li>
	<li>使用仪器软件，自定义程序运行，首先在 100 °C 下平衡 5 分钟，然后以 20 °C/min 的速率升温至 40 °C。 然后，在40°C下等温保持10分钟，然后在N 2中引入5%CO2的混合气体，流速为60mL / min。</li>
	<li>在这种气体混合物条件下将样品保持在40°C下100分钟。执行此程序以通过重量增加来测量 CO2 吸附。这些测量值表示为 wCO2，因为它们评估材料内的 CO2 吸附。这进一步分类为每种合成方法（例如，w CO2_imp（浸渍法）和wCO2_graft（接枝法））。 </li>
	<li>对于循环研究，使用仪器软件，自定义程序运行，首先打开至 100% N2 气体，等温保持 5 分钟，然后以 20 °C/min 升温至 105 °C，等温线保持 5 分钟。</li>
	<li>接下来，以10°C / min的速度下降到40°C，等温线保持1分钟，然后释放N 2中5%CO2的混合物，等温线保持35分钟。重复程序步骤 10 次。</li>
	<li>在软件中，根据需要多次附加此运行以添加额外的循环步骤。确保不要更改平移数，也不要在第一次运行后删除附加运行的重量稳定步骤。这允许用户将多个 10 个周期的运行放在一个方法中。</li>
</ol>4. 使用衰减全反射 （ATR） 附件通过傅里叶变换红外光谱 （FTIR） 分析二氧化硅复合材料
注:与该仪器相关的标准不确定度在峰值强度± 1%，波数± 4 cm−1 ，因此，使用不确定度的线性传播，报告曲线中的强度不确定度± 1.4%。
<ol><li>用低绒湿巾和甲醇清洁 FTIR-ATR 附件上的窗口（金刚石）。</li>
	<li>使用软件的基本测量窗口收集背景光谱。</li>
	<li>使用干净干燥的刮刀，将样品放在FTIR-ATR窗口上。使用ATR压缩探头将样品推入窗口接触。</li>
	<li>通过按基本测量窗口中的"收集样品"按钮 收集样品 光谱，然后从步骤 4.2 中获得的文件中加载相关的背景。</li>
	<li>对所有样品重复步骤 4.1 到 4.4。</li>
</ol>5. 通过扫描电子显微镜（SEM）分析胺浸渍和接枝前后的二氧化硅复合材料
<ol><li>小心地将样品铺在碳导电双面胶带上，将粉末状样品安装在铝桩上。体视显微镜通过增加样品扩散的可见性来帮助完成此过程。</li>
	<li>溅射涂覆每个样品的 5 nm 金钯 （Au-Pd） 导电涂层，以获得最佳成像条件。</li>
	<li>在高真空（即小于 0.4 mPa，3 x 10−6 torr）下，在双光束场发射 SEM 上浸渍或接枝前后对基底二氧化硅材料的表面形态进行成像。 注:所选的光束能量 （1 keV） 和探头电流（6.3 pA 和 25 pA）参数经过优化，图像清晰，充电、伪影和漂移最小。</li>
</ol>

胺化化合物的浸渍和接枝到二氧化硅基材上

<ol>
	<li>Zhu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+direct+air+capture+by+adsorption.">Recent advances in direct air capture by adsorption.</a> Chemical Society Reviews. 51 (15), 6574-6651 (2022).</li><li>Zhao, P., Zhang, G., Yan, H., Zhao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+latest+development+on+amine+functionalized+solid+adsorbents+for+post-combustion+CO2+Capture:+Analysis+review.">The latest development on amine functionalized solid adsorbents for post-combustion CO2 Capture: Analysis review.</a> Chinese Journal of Chemical Engineering. 35 (8), 17-43 (2021).</li><li>Chen, D., Zhang, S., Row, K. H., Ahn, W. -. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amine-silica+composites+for+CO2+capture:+A+short+review.">Amine-silica composites for CO2 capture: A short review.</a> Journal of Energy Chemistry. 26 (5), 868-880 (2017).</li><li>Nie, L., Mu, Y., Jin, J., Chen, J., Mi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+and+considerations+issues+in+solid+adsorbents+for+CO2+capture+from+flue+gas.">Recent developments and considerations issues in solid adsorbents for CO2 capture from flue gas.</a> Chinese Journal of Chemical Engineering. 26 (11), 2303-2317 (2018).</li><li>Nithyashree, N., Manohara, G. V., Maroto-Valer, M. M., Garcia, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+high-temperature+CO2+sorbents+with+improved+long-term+cycling+stability.">Advanced high-temperature CO2 sorbents with improved long-term cycling stability.</a> American Chemical Society Applied Material Interfaces. 12 (30), 33765-33774 (2020).</li><li>Song, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternative+pathways+for+efficient+CO2+capture+by+hybrid+processes-A+review.">Alternative pathways for efficient CO2 capture by hybrid processes-A review.</a> Renewable and Sustainable Energy Review. 82, 215-231 (2018).</li><li>Rochelle, G. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amine+scrubbing+for+CO2+capture.">Amine scrubbing for CO2 capture.</a> Science. 325 (5948), 1625-1654 (2009).</li><li>Vaidye, P. D., Kenig, E. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2-alkanolamine+reaction+kinetics:+A+review+of+recent+studies.">CO2-alkanolamine reaction kinetics: A review of recent studies.</a> Chemical Engineering &amp; Technology. 30 (11), 1467-1474 (2007).</li><li>Veawab, A., Tontiwachwuthikul, P., Chakma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corrosion+behavior+of+carbon+steel+in+the+CO2+adsorption+process+using+aqueous+amine+solutions.">Corrosion behavior of carbon steel in the CO2 adsorption process using aqueous amine solutions.</a> Industrial &amp; Engineering Chemical Research. 38 (10), 3917-3924 (1999).</li><li>Chen, S., Bhattacharjee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trimodal+nanoporous+silica+as+a+support+for+amine-based+CO2+adsorbents:+Improvement+in+adsorption+capacity+and+kinetics.">Trimodal nanoporous silica as a support for amine-based CO2 adsorbents: Improvement in adsorption capacity and kinetics.</a> Applied Surface Science. 396, 1515-1519 (2017).</li><li>Jiao, J., Cao, J., Xia, Y., Zhao, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+adsorbent+materials+for+CO2+capture+by+amine+functionalized+mesoporous+silica+with+worm-hole+framework+structure.">Improvement of adsorbent materials for CO2 capture by amine functionalized mesoporous silica with worm-hole framework structure.</a> Chemical Engineering Journal. 306, 9-16 (2016).</li><li>Guo, X., Ding, L., Kanamori, K., Nakanishi, K., Yang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalization+of+hierarchically+porous+silica+monoliths+with+polyethyleneimine+(PEI)+for+CO2+adsorption.">Functionalization of hierarchically porous silica monoliths with polyethyleneimine (PEI) for CO2 adsorption.</a> Microporous and Mesoporous Materials. 245, 51-57 (2017).</li><li>Fatima, S. S., Borhan, A., Ayoub, M., Ghani, N. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+progress+of+functionalized+silica-based+adsorbents+for+CO2+capture.">Development and progress of functionalized silica-based adsorbents for CO2 capture.</a> Journal of Molecular Liquids. 338, 116913 (2021).</li><li>Cheng, J., Liu, M., Hu, L., Li, Y., Wang, Y., Zhou, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethyleneimine+entwine+thermally-treated+Zn/Co+zeolitic+imidazolate+frameworks+to+enhance+CO2+adsorption.">Polyethyleneimine entwine thermally-treated Zn/Co zeolitic imidazolate frameworks to enhance CO2 adsorption.</a> Chemical Engineering Journal. 364, 530-540 (2019).</li><li>Zagho, M. M., Hassan, M. K., Khraisheh, M., Al-Maadeed, M. A. A., Nazarenko, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+on+recent+advances+in+CO2+separation+using+zeolite+and+zeolite-like+materials+as+adsorbents+and+fillers+in+mixed+matrix+membranes+(MMMs).">A review on recent advances in CO2 separation using zeolite and zeolite-like materials as adsorbents and fillers in mixed matrix membranes (MMMs).</a> Chemical Engineering Journal Advances. 6, 100091 (2021).</li><li>Wang, J., Wang, M., Zhao, B., Qiao, W., Long, D., Ling, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+carbon-supported+solid+amine+sorbents+for+low-temperature+carbon+dioxide+capture.">Mesoporous carbon-supported solid amine sorbents for low-temperature carbon dioxide capture.</a> Industrial &amp; Engineering Chemistry Research. 52 (15), 5437-5444 (2013).</li><li>&#220;nveren, E. E., Monkul, B. O., Sario&#287;lan, S., Karademir, N., Alper, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solid+amine+sorbents+for+CO2+capture+by+chemical+adsorption:+A+review.">Solid amine sorbents for CO2 capture by chemical adsorption: A review.</a> Petroleum. 3 (1), 37-50 (2017).</li><li>Demir, H., Aksu, G. O., Gulbalkan, H. C., Keskin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MOF+membranes+for+CO2+capture:+Past,+present+and+future.">MOF membranes for CO2 capture: Past, present and future.</a> Carbon Capture Science &amp; Technology. 2, 100026 (2022).</li><li>Xu, X., Song, C., Andresen, J. M., Miller, B. G., Scaroni, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+polyethylenimine-modified+mesoporous+molecular+sieve+of+MCM-41+type+as+high-capacity+adsorbent+for+CO2+capture.">Novel polyethylenimine-modified mesoporous molecular sieve of MCM-41 type as high-capacity adsorbent for CO2 capture.</a> Energy &amp; Fuels. 16 (6), 1463-1469 (2002).</li><li>Gelles, T., Lawson, S., Rownaghi, A., Rezaei, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+development+of+amine+functionalized+adsorbents+for+CO2+capture.">Recent advances in development of amine functionalized adsorbents for CO2 capture.</a> Adsorption. 26 (94), 5-50 (2020).</li><li>Rao, N., Wang, M., Shang, Z., Hou, Y., Fan, G., Li, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2+adsorption+by+amine-functionalized+MCM-41:+A+comparison+between+impregnation+and+grafting+modification+methods.">CO2 adsorption by amine-functionalized MCM-41: A comparison between impregnation and grafting modification methods.</a> Energy Fuels. 32 (1), 670-677 (2018).</li><li>Anyanwu, J. T., Wang, Y., Yang, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amine-grafted+silica+gels+for+CO2+capture+including+direct+air+capture.">Amine-grafted silica gels for CO2 capture including direct air capture.</a> Industrial &amp; Engineering Chemistry Research. 59 (15), 7072-7079 (2020).</li><li>Anyanwu, J. -. T., Wang, Y., Yang, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2+capture+(including+direct+air+capture)+and+natural+gas+desulfurization+of+amine-grafted+hierarchical+bimodal+silica.">CO2 capture (including direct air capture) and natural gas desulfurization of amine-grafted hierarchical bimodal silica.</a> Chemical Engineering Journal. 427 (14), 131561 (2022).</li><li>Sanz, R., Calleja, G., Arencibia, A., Sanz-P&#233;rez, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amino+functionalized+mesostructured+SBA-15+silica+for+CO2+capture:+Exploring+the+relation+between+the+adsorption+capacity+and+the+distribution+of+amino+groups+by+TEM.">Amino functionalized mesostructured SBA-15 silica for CO2 capture: Exploring the relation between the adsorption capacity and the distribution of amino groups by TEM.</a> Microporous and Mesoporous Materials. 158, 309-317 (2012).</li><li>Moon, H. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+the+impacts+of+support-polymer+interactions+on+the+dynamics+of+poly(ethyleneimine)+confined+in+mesoporous+SBA-15.">Understanding the impacts of support-polymer interactions on the dynamics of poly(ethyleneimine) confined in mesoporous SBA-15.</a> Journal of the American Chemical Society. 144 (26), 11664-11675 (2022).</li><li>Xu, X., Song, C., Andresen, J. M., Miller, B. G., Scaroni, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+novel+CO2+&amp;#34;molecular+basket&amp;#34;+absorbents+based+on+polymer-modified+mesoporous+molecular+sieve+MCM-41.">Preparation and characterization of novel CO2 &amp;#34;molecular basket&amp;#34; absorbents based on polymer-modified mesoporous molecular sieve MCM-41.</a> Microporous and Mesoporous Materials. 62 (1-2), 29-45 (2003).</li><li>Sousa, J. A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=H2S+and+H2O+combined+effect+on+CO2+capture+by+amino+functionalized+hollow+microsphere+silicas.">H2S and H2O combined effect on CO2 capture by amino functionalized hollow microsphere silicas.</a> Industrial &amp; Engineering Chemistry Research. 60 (28), 10139-10154 (2021).</li><li>Rim, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sub-ambient+temperature+direct+air+capture+CO2+using+amine-impregnated+MIL-101(Cr)+enables+ambient+temperature+CO2.">Sub-ambient temperature direct air capture CO2 using amine-impregnated MIL-101(Cr) enables ambient temperature CO2.</a> JACS Au. 2 (2), 380-393 (2022).</li></ol>

所有作者均未披露任何竞争性利益冲突。本文中使用的程序的完整描述需要识别某些商业产品及其供应商。包含此类信息绝不应被解释为表明此类产品或供应商已获得NIST的认可，或由NIST推荐，或者它们一定是所述目的的最佳材料、仪器、软件或供应商。

本文中描述的方法旨在提供制备浸渍和接枝胺二氧化硅复合吸附剂的方案。我们记录的程序是基于对文献中报道的技术和我们实验室中改进的技术的回顾。1,2,3.这些材料的制备在二氧化碳去除研究领域中很有用，可以开发或基准测试可用于降低大气（直接空气捕获）或工业过程中（点源捕获）中二氧化碳排放的其他材料。在固体胺吸附剂中，通常使用介孔二氧化硅。二氧化硅基质往往具有简单的合成或可以在商业上购买，其结构特性使其成为浸渍或接枝胺基固体吸附剂的良好选择21。在此过程中，MCM-41 被用作二氧化硅基质，因为它的表面积大，孔径分布在 35 Å 和 38 Å 之间很窄。然而，另一种常用的二氧化硅载体是 SBA-15，由于其大表面积、孔体积和均匀的介孔尺寸24，它也被用于碳捕获研究。通过浸渍利用 MCM-41 和 PEI 的系统研究表明，随着 PEI 负载量的增加，CO2 吸附量增加26。Xu 及其同事26 给出了浸渍 MCM-41 二氧化硅复合材料的重量损失，Sousa 及其同事27 给出了接枝二氧化硅复合材料的重量损失，他们实验了 H 2 S 和 H 2 O 对 CO2捕获的影响。Xu 和同事26 发现，他们的 MCM-41 在 PEI 负载量为 50% （wt%） 时具有 112 mg CO2/g 吸附剂的吸附能力。这些浸渍材料的减肥TGA也出现在手稿中。相比之下，本手稿中 MCM-41 59.9 % （wt %） 浸渍的 PEI 的容量为 61.6 mg CO2/g 吸附剂。虽然这似乎比报告的量少得多，但考虑到测量参数不同 - Xu 及其同事将样品加热至 75 °C，在 N 2 中混合 99.8% 的 CO2，流速为 100 mL/min 150 分钟。温度升高和接近 100% CO 2 的实验条件可能都有助于 CO2 的吸附。这凸显了比较实验程序不同的研究的挑战。
即使是浸渍等看似简单的方法，溶剂的选择、二氧化硅/溶剂浓度、胺/溶剂浓度、搅拌/混合方法、温度和混合时间在文献中也有很大差异。本文旨在描述一种制作这些材料的方法，但每个研究人员都可以根据自己的研究目标进行选择。此外，这些方法适用于其他用于碳捕获的吸附剂基质。我们的目的是通过为这种方法的此类工作提供起点，帮助促进对二氧化碳去除材料的研究。
许多研究表明，对于浸渍胺和接枝胺，二氧化硅复合材料结构中胺的位置可能会发生变化。负载PEI的浸渍材料在表面具有较高的功能化程度（即胺含量），可以防止CO 2扩散到孔隙中1,2,3,24。孔隙堵塞与较冷的反应温度条件、较高的胺负载量和空间位阻有关，从而降低了胺位点的可及性和吸附能力28。
接枝材料已被证明在孔道内具有胺，因此 CO2 扩散很容易发生在整个结构中，从而最大限度地提高捕获效率24,25。由于接枝材料和氨基硅烷中胺含量的变化，将接枝胺二氧化硅复合材料相互比较会带来困难。
然而，"相同材料"内研究之间的可比性仍然存在显着局限性，例如（1）合成，（2）材料和（3）测量的变化。首先，虽然许多研究和评论文章描述了浸渍或接枝二氧化硅材料的制备，但合成方案往往各不相同，对合成中最关键的步骤没有明确的指南。其次，从外部供应商采购的二氧化硅基质与通过这些协议中使用的合成路线制备的二氧化硅基质之间存在性能差异。由于PEI摩尔质量、氨基硅烷中的胺含量以及接枝或负载百分比的变化，很难比较这些不同材料之间测得的CO2 吸附能力。第三，CO2 吸附能力可以使用许多不同类型的商业或专门设计的测量工具进行测量，所有这些工具都具有不同的相关测量不确定度。气源中 CO2 的总百分比、气体流速、活化、吸附、解吸温度的选择以及气源内的湿度可能因研究和仪器而异。在比较单个材料的吸附能力时，所有这些实验参数都是重要的考虑因素。
虽然该程序侧重于二氧化硅基材，但消除碳排放和降低大气中二氧化碳浓度的 总体目标是一个复杂的、多方面的问题，需要解决材料创新问题，需要就要报告的测量参数达成共识，并明确指出关键的程序步骤。因此，继续研究具有 CO2 吸附剂功能的新型固体支撑吸附剂对于实现既定气候目标变得越来越重要。本文强调了社区就相关参数达成共识的必要性，并展示了对基准材料的需求。

过去几十年来，人为的二氧化碳排放被广泛认为是驱动温室气体效应的主要因素，因此也是相关的气候变化1,2,3,4。CO2 捕获有两种通用方法，点源和直接空气捕获。50 多年来，湿法洗涤 CO 2 捕集技术一直被用于行业内的点源捕集，以减少 CO2 排放 5,6。这些技术基于液相胺，液相胺在干燥条件下与 CO2 反应形成氨基甲酸酯，在水存在下形成碳酸氢盐7,8，见图 1。在大点（工业）源利用碳捕获和封存的主要原因是为了防止大量 CO2 的进一步释放，从而对大气中 CO2 的总浓度产生中性影响。然而，点源碳捕集系统存在一些缺点，例如设备腐蚀、溶剂降解和再生的高能源需求9.直接空气捕获 （DAC） 不仅能减少排放，还有助于从大气中去除 CO2。去除现有的二氧化碳对于限制持续的气候变化是必要的。 DAC 是一种新兴方法，必须解决在大气条件（400 至 420 ppm）中去除低浓度 CO 2 的困难，在各种不同的环境条件下运行，并满足对可多次重复使用的具有成本效益的材料的需求 1,2,3 .需要大量工作来确定满足这些要求的材料，这将加速DAC的采用并提高其经济可行性。最重要的是，需要就测量的关键参数建立社区共识，这对于开发基准材料至关重要。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65845/65845fig01.jpg"> 图 1:预期的液胺吸附剂 CO2 捕获机理示意图。 顶部反应在干燥条件下，底部反应在水分存在下。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig01large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
为了弥补这些缺点，对新型多孔材料技术的大量研究和开发产生了一系列有前途的材料，这些材料有可能被用作DAC的捕获材料或基板。此类材料的一些实例包括介孔二氧化硅物种 10、11、12、13、沸石 14、15、活性炭 16、17 和金属有机框架 18。许多固体负载的胺吸附剂还显示出更高的耐水性，这是通过DAC方法去除CO2的重要考虑因素。对于 DAC 应用，研究人员必须考虑潮湿/干燥的环境条件、热/冷温度以及大气中整体稀薄的 CO2 浓度。在各种基材中，二氧化硅因其孔径可调、表面功能化能力和大表面积而被普遍使用1,2,3。本文描述了浸渍和接枝胺-二氧化硅复合材料的典型合成程序和主要特征（图2）。直接合成，即材料由基质和胺两种成分原位制成，是另一种常用的方法2.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/65845/65845fig02.jpg"> 图 2:浸渍示意图。 PEI和二氧化硅基质通过扩散在甲醇中的混合（上图）和通过共价系留法接枝的胺-二氧化硅复合材料（下图）。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig02large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
浸渍是一种通过范德华力和胺与二氧化硅表面之间的氢键将胺物理吸附到表面（在本例中为多孔二氧化硅介质）上的方法，见 图2。通常使用乙醇和甲醇等溶剂来促进分子扩散到基材的多孔结构中。还可以加热溶液以增加高摩尔质量多胺的溶解度，从而增加胺在孔内渗透的均匀性。在浸渍材料的情况下，引入二氧化硅基材的胺量由胺的初始量和基材的表面积决定。如果引入的胺量超过二氧化硅基材的可用表面积，则胺类将在其表面团聚。这种团聚是显而易见的，因为浸渍材料看起来具有凝胶状涂层，通常是黄色的，而不是预期的白色和粉末状外观1。在众多类型的胺基固体吸附剂中，聚乙烯亚胺（PEI）和四乙烯五胺（TEPA）因其高稳定性和高氮含量而应用最广泛20。对于物理浸渍体系，胺的理论负载量可以根据基材的预加权量和胺的密度计算得出。物理浸渍的明显优势在于制备它的合成程序简单明了，并且由于二氧化硅基底的高孔隙率，有可能产生大量胺含量。相反，胺在二氧化硅中的稳定性是有限的，因为胺和二氧化硅载体之间没有共价键。因此，经过多次循环的CO2 吸收和通过加热或蒸汽再生后，胺可以从孔隙中浸出。尽管存在这些缺点，但用于DAC的这种材料的实施对于从大气中去除CO2 具有很大的希望。
制备DAC材料的另一种选择是接枝。接枝是一种通过化学反应将胺固定在多孔二氧化硅基底上的方法，如图2所示。该反应通过氨基硅烷与表面的硅醇官能团反应进行，从而产生共价键。因此，二氧化硅基底表面官能团的数量影响接枝胺密度21,22。与胺浸渍吸附剂相比，化学接枝方法具有较低的CO2吸附能力，这主要是由于胺负载量低21。相反，化学接枝胺由于其共价结合结构而具有更高的热稳定性。这种稳定性可用于材料的再生，因为吸附剂（如接枝二氧化硅）被加热和加压以去除捕获的 CO2 以供重复使用，从而节省材料和成本。在典型的合成过程中，将介孔二氧化硅底物分散在溶剂（例如无水甲苯）中，然后加入氨基硅烷。然后洗涤所得样品以除去未反应的氨基硅烷。据报道，氨基硅烷密度的改善是通过加水实现的，特别是用SBA-15，以扩大孔径23。本文将要描述的嫁接程序使用湿敏技术。因此，不会使用额外的水。接枝氨基硅烷材料在DAC中的应用前景广阔，因为它们在CO2吸附和解吸过程中具有预期的稳定性。然而，这种方法的主要缺点包括这些材料的反应/制备复杂，导致成本增加，以及它们的整体 CO2 吸附能力较低，这意味着需要更大的数量。
总体而言，许多先前研究的结果表明，底物的结构和胺相关的修饰对吸附性能有重大影响，具体研究利用透射电子显微镜 （TEM） 和准弹性中子散射 （QENS） 等技术来充分表征这些材料24,25.换句话说，基材的结构特性（例如孔隙率和表面积）决定了胺负载量，因此增加这些参数可以提高 CO2 容量24,25。对衬底材料和制备工艺的优化和设计的持续研究对于开发高性能DAC吸附剂至关重要。这项工作的目的是为浸渍和接枝胺合成提供指导，以期促进合成技术的透明度。在文献中，并不总是描述溶剂、底物和胺含量的具体细节，因此很难理解实验负载量与胺-二氧化硅复合材料定量测量之间的相关性。本文将提供确切的加载量和实验程序的详细描述，以更好地促进这些类型的比较。

<table><tbody><tr><td>Anhydrous methanol</td><td>Sigma-Aldrich</td><td>322415</td><td>Does not come with sure-seal</td></tr><tr><td>Anhydrous toluene</td><td>Sigma-Aldrich</td><td>244511</td><td>Comes with sure-seal</td></tr><tr><td>Ceramic Stirring Hot Plate</td><td>NA</td><td>NA</td><td>The size, watage, and thermal capabilities of the stirr plate will differ depending on individual lab facilities.</td></tr><tr><td>Fourier Transform Infrared Spectroscopy (FTIR)&amp;nbsp;</td><td>Nicolet i550 series spectrometer</td><td>NA</td><td>Run on OMNIC standard software</td></tr><tr><td>Gastight syringe&amp;nbsp;</td><td>NA</td><td>NA</td><td>As long as the gas tight syringe has a PTFE plunger and luer tip, is suited for air sensitive technique and can be used in this protocol.&amp;nbsp;</td></tr><tr><td>Glass vial</td><td>NA</td><td>NA&amp;nbsp;</td><td>As long as the vial is made if borosilicate glass and has a screw based cap the brand name, size, or general shape does not matter for the protocol.</td></tr><tr><td>MCM-41 silica</td><td>ACS Material&amp;nbsp;</td><td>MSM41A01&amp;nbsp;</td><td>Cas no. 7631-86-9</td></tr><tr><td>Metal needle</td><td>NA</td><td>NA</td><td>Syringe needles need to be stainless steel. It is recommended to determine length and outerdiameter of needle by what will be transferred using the gas tight syringe. For large quantities of liquid a larger outer diameter will improve transfer rates.&amp;nbsp;</td></tr><tr><td>N&amp;rsquo;-(3-trimethylsilyl propyl) diethyleneamine (DAS)</td><td>Sigma-Aldrich</td><td>104884</td><td>Comes with sure-seal&amp;nbsp;</td></tr><tr><td>Polyethyleneimine (PEI)</td><td>Sigma-Aldrich</td><td>408719</td><td>Does not come with sure-seal</td></tr><tr><td>Schlenk round bottom flask</td><td>ChemGlass AirFree</td><td>NA</td><td>As long as the flask is suited for high pressure and temperture but the brand name, size, or general shape does not matter for the protocol</td></tr><tr><td>Thermogravemetric Anlysis (TGA)&amp;nbsp;</td><td>TA Advantage</td><td>NA</td><td>550 series from Waters and TA Instruments</td></tr></tbody></table>

a synthetic methodology for preparing impregnated and grafted amine-based silica composites for carbon capture

最近，通过使用碳捕获材料作为点源或直接空气捕获 （DAC） 方法，在减少或减轻 CO2 排放方面做出了重大努力。这项工作的重点是用于DAC的胺官能团化CO2 吸附剂。这些材料具有低再生能耗和高吸附能力，因此具有去除 CO2 的前景。将胺类掺入多孔基材中结合了胺类对 CO2 的亲和力以及多孔基材的大孔体积和表面积的优点。胺基CO2 吸附剂的制备常用方法有三种，具体取决于胺种类、材料载体和制备方法的选择。这些方法是浸渍、接枝或化学合成。二氧化硅是基板材料的普遍选择，因为它具有可调节的孔径、耐湿性、温度稳定性以及在 DAC 应用中吸附低浓度 CO2 的能力。本文描述了浸渍和接枝胺-二氧化硅复合材料的典型合成方法和主要属性。

TGA通常用于量化这些材料在二氧化硅表面负载或接枝的胺量。得到的TGA曲线显示，在60 °C至100 °C之间，残留溶剂和水的损失，在衍生物重量（重量%/°C）曲线中显示为第一个峰，胺的损失在衍生物重量曲线（重量%/°C）中显示为第二个峰。对于PEI浸渍的二氧化硅，胺的损失预计将出现在200°C至300°C左右，这是衍生物重量曲线中的第二个峰，而对于DAS接枝二氧化硅，胺的损失预计将出现在350°C至550°C左右（图6）。总重量损失表明负载或接枝到二氧化硅基底上的胺的量，是判断合成质量的重要表征参数。对于PEI浸渍的样品，TGA的w胺（w amine_TGA_imp）= 59.2%±0.3%（n = 3），而实验（wamine_exp_graft）= 59.9%（图6B）。对于DAS接枝标本，w amine_TGA_graft = 22.3 % ± 0.1 % （n = 3），而当合成重复三次时，wamine_exp_graft = 90.0 %（图6A）。 
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/65845/65845fig06.jpg"> 图6:TGA。 （A） PEI浸渍在w amine_exp_imp = 59.9 %，w amine_TGA_imp = 59.2 %±0.3 %（n = 3），（B）接枝材料在w amine_exp = 90.0 %时观察到，wamine_TGA = 22.3 % ± 0.2 % （n = 3）。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig06large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
在图7中，使用TGA在N 2中5%CO 2，流速为60 mL / min，并在40 °C下保持60 min，测量CO2的总吸附量。在图7A中，显示了PEI浸渍试样的CO 2吸附曲线，平均CO2%吸附重量（wCO2_imp）为6.16%±0.2%（n = 3）。在图7B中，显示了DAS接枝标本的CO2吸附曲线，w CO2_graft = 2.03 %±0.04 % （n = 3）。在这些TGA曲线中，基线被校正为从100%开始。
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/65845/65845fig07.jpg"> 图 7:CO2 吸附的 TGA 曲线。 （A） 浸渍 PEI MCM-41 试样 wCO2_imp= 6.16 % ± 0.3 % （n = 3）。（B） 移植的 DAS MCM-41 标本 wCO2_graft = 2.03 % ± 0.04 % （n = 3）。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig07large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
傅里叶变换红外-ATR光谱是一种振动光谱，通常用于了解材料的化学结构。图 8 显示了纯 PEI、DAS 和 MCM-41 与 PEI 浸渍或 DAS 接枝 MCM-41 材料的 FTIR-ATR 光谱。从2500 cm-1到3600 cm-1的不同峰归因于胺化材料预期的基于胺的N-H信号。当比较浸渍和接枝材料的光谱时，观察到峰强度降低，这归因于接枝材料中胺的含量较低。在光谱中可以看到对应于 Si-O-Si 的强峰范围为 400 cm-1 至 1200 cm-1。所呈现的光谱经过校正，经过衰减的全反射率校正，然后通过仪器的软件自动进行基线校正。
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/65845/65845fig08.jpg"> 图8:FTIR光谱。 纯PEI、MCM-41、DAS、DAS接枝试样和PEI浸渍材料试样的代表性FTIR光谱。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig08large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
在图9中，将未改变的MCM-41的SEM显微照片与用PEI浸渍的MCM-41（w amine_TGA_imp = 59.2%）和用DAS接枝的MCM-41（wamine_TGA_graft = 22.3%）的形态和表面差异进行比较。
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/65845/65845fig09.jpg"> 图 9:SEM 图像 。 （A） PEI 浸渍的 MCM-41，（B） 纯 MCM-41 和 （C） DAS 接枝的 MCM-41。 <a href="https://www.jove.com/files/ftp_upload/65845/65845fig09large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
在图 10 和图 11 中，使用 TGA 测量纯起始材料，例如 MCM-41、DAS 和 PEI 800，作为失重和 CO2 吸附的基线参考。在图10A中，整齐的MCM-41 TGA曲线可以看作是缓慢、逐渐的重量损失，但衍生物重量（重量%/°C）没有明显的峰值。在图10B中，可以看到整齐的PEI 800 TGA曲线，总失重范围为200 °C至370 °C。
<img alt="Figure 10" class="xfigimg" src="/files/ftp_upload/65845/65845fig10.jpg"> 图 10:TGA 曲线。（A） 纯 MCM-41 wMCM41 = 8.58 % ± 0.5 % （n =3 ）。（B） PEI 800 分子量 wPEI = 98.9 % ± 0.9 % （n = 3）。。<a href="https://www.jove.com/files/ftp_upload/65845/65845fig10large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
<img alt="Figure 11" class="xfigimg" src="/files/ftp_upload/65845/65845fig11.jpg"> 图 11:TGA 曲线。 （A） 纯 MCM-41 wCO2 的 CO 2 吸附 = 0.223 % ± 0.2 % （n = 3）。（B） 纯 PEI 800 wCO2 的 CO2 吸附率 = 0.879 % ± 0.3 % （n = 3）。（C） 纯 DAS wCO2 的 CO2 吸附率 = 0.247 % ± 0.1 % （n = 3）。<a href="https://www.jove.com/files/ftp_upload/65845/65845fig011large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>
在图11A中，显示了纯MCM-41的CO 2吸附曲线，其中CO2吸附最小，CO2 = 0.222 %±0.2 %（n = 3）。在图 11B 中，显示了 PEI 800 的 CO 2 吸附曲线，其中 CO 2 吸附最小，CO2 = 0.879 % ± 0.3 % （n = 3）。 在图11C中，显示了CO 2吸附最少的纯DAS的CO2吸附曲线，即CO2 = 0.247 %±0.1 %（n = 3）。请注意，纯材料的吸附率很低，因为 CO2 吸附仅发生在暴露于混合气体环境的表面。值得注意的是，DAS 对空气和湿气敏感，并且在加载到 TGA 的过程中会暴露在空气中，这可能会影响其吸附 CO2 的能力。
在图 12 中，显示了浸渍的 MCM-41（图 12A）和接枝的 MCM-41（图 12B）的 CO 2 吸附和解吸循环曲线。在该方案中，首先通过在100%N 2下加热至105°C5分钟来激活样品，然后升温至40°C并保持1分钟，然后施用N 2中的5%CO2的混合物35分钟。然后重复此过程（图12C）。该图显示了十个重复循环，随着时间的推移，材料的吸附能力会降低。可以通过 https://doi.org/10.18434/mds2-3017 的机构数据资产管理（MIDAS）访问数据。
<img alt="Figure 12" class="xfigimg" src="/files/ftp_upload/65845/65845fig12.jpg"> 图 12:循环 TGA 吸附和解吸研究。 （A） PEI 浸渍的 MCM-41，（B） DAS 接枝的 MCM-41，以及 （C） （A） 和 （B） 程序运行的温度曲线。<a href="https://www.jove.com/files/ftp_upload/65845/65845fig12large.jpg" target="_blank">请点击这里查看此图的较大版本.</a>

Watch this Scientific Journal Video about Standardizing the Development of Amine-Based Silica Composites as CO2 Adsorbents for Direct Air Capture at JoVE.com

作者聚焦:胺基二氧化硅复合材料作为直接空气捕获的 CO2 吸附剂的标准化开发 

这项工作旨在促进将胺化化合物浸渍或接枝到二氧化硅基质上的标准化技术的发展，这些技术通常在文献中被广泛描述。将详细讨论溶剂、底物、胺的具体用量以及其他重要实验参数的值。

一种制备浸渍接枝胺基二氧化硅复合材料的合成方法

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

NIST的科学家正在开发关键的测量科学和基准材料，以加速创新，并探索及时、有效和可扩展的直接空气捕获（DAC），用于从大气中去除二氧化碳。这项工作的重点是推广用于DAC应用的胺官能化二氧化硅复合材料的制备、测量和报告的最佳实践。该协议通过提供明确的指南和条件，同时确定关键步骤，解决了 DAC 材料的突出研究挑战和可重复的合成程序。此外，我们的目标是通过明确记录特定的吸附实验参数，对这些材料的二氧化碳能力进行有意义的比较。我们正在将工作转向表征基准材料和开发标准技术，以提高报告结果的可比性和可信度。

a-synthetic-methodology-for-preparing-impregnated-grafted-amine-based

Nanyang Technological University

Research

JoVE Journal

Chemistry

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

2.2K 次观看.  National Institute of Standards and Technology (NIST). NIST的科学家正在开发关键的测量科学和基准材料，以加速创新，并探索及时、有效和可扩展的直接空气捕获（DAC），用于从大气中去除二氧化碳。这项工作的重点是推广用于DAC应用的胺官能化二氧化硅复合材料的制备、测量和报告的最佳实践。该协议通过提供明确的指南和条件，同时确定关键步骤，解决了 DAC 材料的突出研究挑战和可重复的合成程序。此外，我们的目?...

视频: 作者聚焦:胺基二氧化硅复合材料作为直接空气捕获的 CO2 吸附剂的标准化开发 

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

科研

化学

Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and lignin. Layer-by-layer (LbL) assembly process which relies on the assembly of oppositely charged molecules from aqueous solutions was used to build a freestanding composite film of isolated wood polymers of lignin and oxidized nanofibril cellulose (NFC). To facilitate the assembly of these negatively charged polymers, a positively charged polyelectrolyte, poly(diallyldimethylammomium chloride) (PDDA), was used as a linking layer to create this simplified model cell wall. The layered adsorption process was studied quantitatively using quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. The results showed that layer mass/thickness per adsorbed layer increased as a function of total number of layers. The surface coverage of the adsorbed layers was studied with atomic force microscopy (AFM). Complete coverage of the surface with lignin in all the deposition cycles was found for the system, however, surface coverage by NFC increased with the number of layers. The adsorption process was carried out for 250 cycles (500 bilayers) on a cellulose acetate (CA) substrate. Transparent free-standing LBL assembled nanocomposite films were obtained when the CA substrate was later dissolved in acetone. Scanning electron microscopy (SEM) of the fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle (PDDA-Lignin-PDDA-NC) was estimated to be 17 nm for two different lignin types used in the study. The data indicates a film with highly controlled architecture where nanocellulose and lignin are spatially deposited on the nanoscale (a polymer-polymer nanocomposites), similar to what is observed in the native cell wall.

The objective of this research was to form synthetic plant cell wall tissue using layer-by-layer assembly of nanocellulose fibrils and isolated lignin assembled from dilute aqueous suspensions.&#160; Surface measurement techniques of quartz crystal microbalance and atomic force microscopy were used to monitor the formation of the polymer-polymer nanocomposite material.

朝仿生学木：纳米纤维素，木质素的装配式自由站立电影和合成聚阳离子

Woody materials are comprised of plant cell walls that contain a layered secondary cell wall composed of structural polymers of polysaccharides and ...

Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10-3 molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

This article describes a rapid supercritical extraction method for fabricating silica aerogels. By utilizing a confined mold and hydraulic hot press, monolithic aerogels can be made in eight hours or less.

通过快速超临界萃取法制备二氧化硅气凝胶巨石

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The ...

Manufacturing of Three-dimensionally Microstructured Nanocomposites through Microfluidic Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite in&#64257;ltration of 3D interconnected microfluidic networks. The manufacturing of the reinforced beams begins with the fabrication of microfluidic networks, which involves layer-by-layer deposition of fugitive ink filaments using a dispensing robot, filling the empty space between filaments using a low viscosity resin, curing the resin and finally removing the ink.&#160;Self-supported 3D structures with other geometries and many layers (e.g.&#160;a few hundreds layers) could be built using this method. The resulting tubular micro&#64258;uidic networks are then infiltrated with thermosetting nanocomposite suspensions containing nanofillers (e.g.&#160;single-walled carbon nanotubes), and subsequently cured. The infiltration is done by applying a pressure gradient between two ends of the empty network (either by applying a vacuum or vacuum-assisted microinjection). Prior to the infiltration, the nanocomposite suspensions are prepared by dispersing nanofillers into polymer matrices using ultrasonication and three-roll mixing methods. The nanocomposites (i.e.&#160;materials infiltrated) are then solidified under UV exposure/heat cure, resulting in a 3D-reinforced composite structure. The technique presented here enables the design of functional nanocomposite macroscopic products for microengineering applications such as actuators and sensors.

Three-dimensional (3D) microstructured composite beams are fabricated through the directed and localized infiltration of nanocomposites into 3D porous microfluidic networks. The flexibility of this manufacturing method enables the utilization of different thermosetting materials and nanofillers in order to achieve a variety of functional 3D reinforced nanocomposite macroscopic products.

通过微流体渗透制备三维微结构纳米复合材料的制造

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

快速超临界萃取制备催化气凝胶的制备与试验研究

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

Preparation of Functional Silica Using a Bioinspired Method

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally purify the same by acid elution. By combining sodium silicate with a polyfunctional bioinspired additive, silica is rapidly formed at ambient conditions upon neutralization. 
The effect of neutralization rate and biomolecule addition point on silica yield are investigated, and biomolecule immobilization efficiency is reported for varying addition point. In contrast to other porous silica synthesis methods, it is shown that the mild conditions required for bioinspired silica synthesis are fully compatible with the encapsulation of delicate biomolecules. Additionally, mild conditions are used across all synthesis and modification steps, making bioinspired silica a promising target for the scale-up and commercialization as both a bare material and active support medium.
The synthesis is shown to be highly sensitive to conditions, i.e., the neutralization rate and final synthesis pH, however tight control over these parameters is demonstrated through the use of auto titration methods, leading to high reproducibility in reaction progression pathway and yield. 
Therefore, bioinspired silica is an excellent active material support choice, showing versatility towards many current applications, not limited to those demonstrated here, and potency in future applications.

Here, we present a protocol to synthesize bioinspired silica materials and immobilize enzymes therein. Silica is synthesized by combining sodium silicate and an amine &#39;additive&#39;, which neutralize at a controlled rate. Material properties and function can be altered either by in situ enzyme immobilization or post-synthetic acid elution of encapsulated additives.

用 Bioinspired 法制备功能性二氧化硅

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

合成纳米碳和二氧化硅矩阵的表面性能

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

利用表面有机金属化学方法，利用硅支持的催化剂进行Imine金属分析

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

Aesthetically Enhanced Silica Aerogel Via Incorporation of Laser Etching and Dyes

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid supercritical extraction method, large silica aerogel monolith (10 cm x 11 cm x 1.5 cm) can be fabricated in about 10 h. Dyes incorporated into the precursor mixture result in yellow-, pink- and orange-tinged aerogels. Text, patterns, and images can be etched onto the surface (or surfaces) of the aerogel monolith without damaging the bulk structure. The laser engraver can be used to cut shapes from the aerogel and form colorful mosaics.

This protocol describes a method for etching text, patterns, and images onto the surface of silica aerogel monoliths in native and dyed form and assembling the aerogels into mosaic designs.

通过将激光蚀刻和染料结合，美学增强硅气凝胶

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid ...