Name: fabrication and testing of catalytic aerogels prepared via rapid supercritical extraction
Uploaded: 2018-08-31T12:30:00.000+00:00
Duration: 9 min 28 s
Description: Watch this Scientific Journal Video about Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction at JoVE.com

催化气凝胶合成方法的发展由国家科学基金会 (NSF) 资助。DMR-1206631。UCAT 的设计和建造是通过 NSF 资助号提供的。CBET-1228851。另外的经费由联合学院教职员研究基金提供。作者还想确认托宾、奥得河 Bechu、瑞安 Bouck、亚当法院和 Vinicius 席尔瓦的贡献。

<ol>
	<li>Aegerter, M. A., Leventis, N., Koebel, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Aerogels Handbook. , (2011).</li><li>Pierre, A. C., Pajonk, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemistry+of+Aerogels+and+Their+Applications.">Chemistry of Aerogels and Their Applications.</a> Chem. Rev. 102 (11), 4243-4266 (2002).</li><li>Schneider, M., Baiker, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aerogels+in+Catalysis.">Aerogels in Catalysis.</a> Catal. Rev. 37, 515-556 (1995).</li><li>Vallribera, A., Molins, E., Astruc, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aerogel+Supported+Nanoparticles+in+Catalysis.">Aerogel Supported Nanoparticles in Catalysis.</a> Nanoparticles and Catalysis. , (2007).</li><li>Amonette, J. E., Matyas, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalized+silica+aerogels+for+gas-phase+purification,+sensing,+and+catalysis:+A+review.">Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review.</a> Mircopor. Mesopor. Mater. 250, 100-119 (2017).</li><li>Juhl, S. J., Dunn, N. J. H., Carroll, M. K., Anderson, A. M., Bruno, B. A., Madero, J. E., Bono, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epoxide-Assisted+Alumina+Aerogels+by+Rapid+Supercritical+Extraction.">Epoxide-Assisted Alumina Aerogels by Rapid Supercritical Extraction.</a> J. Non-Cryst. Solids. 426, 141-149 (2015).</li><li>Bono, M. S., Dunn, N. J. H., Brown, L. B., Juhl, S. J., Anderson, A. M., Bruno, B. A., Mahony, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catalyst,+Catalytic+Converter+and+Method+for+the+Production+Thereof.">Catalyst, Catalytic Converter and Method for the Production Thereof.</a> US Patent. , (2016).</li><li>Smith, L. C., Anderson, A. M., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+vanadia-containing+aerogels+by+rapid+supercritical+extraction+for+applications+in+catalysis.">Preparation of vanadia-containing aerogels by rapid supercritical extraction for applications in catalysis.</a> J. Sol-Gel Sci. Technol. 77, 160-171 (2016).</li><li>Bouck, R. M., Anderson, A. M., Prasad, C., Hagerman, M. E., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cobalt-alumina+Sol+Gels:+Effects+of+Heat+Treatment+on+Structure+and+Catalytic+Ability.">Cobalt-alumina Sol Gels: Effects of Heat Treatment on Structure and Catalytic Ability.</a> J. Non-Cryst. Solids. 453, 94-102 (2016).</li><li>Anderson, A. M., Donlon, E. A., Forti, A. A., Silva, V., Bruno, B. A., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Characterization+of+Copper-Nanoparticle-Containing+Silica+Aerogel+Prepared+Via+Rapid+Supercritical+Extraction+for+Applications+in+Three-Way+Catalysis.">Synthesis and Characterization of Copper-Nanoparticle-Containing Silica Aerogel Prepared Via Rapid Supercritical Extraction for Applications in Three-Way Catalysis.</a> MRS Advances. , 1-6 (2017).</li><li>Tobin, Z. M., Posada, L. F., Bechu, A. M., Carroll, M. K., Bouck, R. M., Anderson, A. M., Bruno, B. A. <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+Copper-containing+Alumina+and+Silica+Aerogels+for+Catalytic+Applications.">Preparation and Characterization of Copper-containing Alumina and Silica Aerogels for Catalytic Applications.</a> J. Sol-Gel Sci. Technol. , (2017).</li><li>Heck, R., Farrauto, R., Gulati, 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> Catalytic Air Pollution Technology. , (2009).</li><li>Gauthier, B. M., Bakrania, S. D., Anderson, A. M., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Fast+Supercritical+Extraction+Technique+for+Aerogel+Fabrication.">A Fast Supercritical Extraction Technique for Aerogel Fabrication.</a> J. Non-Cryst. Solids. 350, 238-243 (2004).</li><li>Gauthier, B. M., Anderson, A. M., Bakrania, S. D., Mahony, M. K., Bucinell, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+and+Device+for+Fabricating+Aerogels+and+Aerogel+Monoliths+Obtained+Thereby.">Method and Device for Fabricating Aerogels and Aerogel Monoliths Obtained Thereby.</a> US Patent No. , (2008).</li><li>Gauthier, B. M., Anderson, A. M., Bakrania, S. D., Mahony, M. K., Bucinell, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+and+Device+for+Fabricating+Aerogels+and+Aerogel+Monoliths+Obtained+Thereby.">Method and Device for Fabricating Aerogels and Aerogel Monoliths Obtained Thereby.</a> US Patent. , (2011).</li><li>Roth, T. B., Anderson, A. M., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+a+Rapid+Supercritical+Extraction+Aerogel+Fabrication+Process:+Prediction+of+Thermodynamic+Conditions+During+Processing.">Analysis of a Rapid Supercritical Extraction Aerogel Fabrication Process: Prediction of Thermodynamic Conditions During Processing.</a> J. Non-Cryst. Solids. 354 (31), 3685-3693 (2008).</li><li>Carroll, M. K., Anderson, A. M., Gorka, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparing+Silica+Aerogel+Monoliths+via+a+Rapid+Supercritical+Extraction+Method.">Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method.</a> J. Vis. Exp. (84), e51421 (2014).</li><li>Harper-Leatherman, A. S., Pacer, E. R., Kosciuszek, N. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulating+Cytochrome+c+in+Silica+Aerogel+Nanoarchitectures+without+Metal+Nanoparticles+while+Retaining+Gas-phase+Bioactivity.">Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity.</a> J. Vis. Exp. (109), e53802 (2016).</li><li>Subrahmanyam, R., Gurikov, P., Meissner, I., Smirnova, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+Biopolymer+Aerogels+Using+Green+Solvents.">Preparation of Biopolymer Aerogels Using Green Solvents.</a> J. Vis. Exp. (113), e54116 (2016).</li><li>Campbell, P. G., Worsley, M. A., Hiszpanski, A. M., Baumann, T. F., Biener, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Functionalization+of+3D+Nano-graphene+Materials:+Graphene+Aerogels+and+Graphene+Macro+Assemblies.">Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies.</a> J. Vis. Exp. (105), e53235 (2015).</li><li>Kapteijn, F., Stegenga, S., Dekker, N. J. J., Bijsterbosch, J. W., Moulijn, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternatives+to+noble+metal+catalysts+for+automotive+exhaust+purification.">Alternatives to noble metal catalysts for automotive exhaust purification.</a> Catalysis Today. 16 (2), 273-287 (1993).</li><li>Baumann, T., Gash, A., Chinn, S., Sawvel, A., Maxwell, R., Satcher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+high-surface-area+alumina+aerogels+without+the+use+of+alkoxide+precursors.">Synthesis of high-surface-area alumina aerogels without the use of alkoxide precursors.</a> Chem. Mater. 17, 395-401 (2005).</li><li>Bruno, B. A., Anderson, A. M., Carroll, M. K., Brockmann, P., Swanton, T., Ramphal, I. A., Palace, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Benchtop+Scale+Testing+of+Aerogel+Catalysts.">Benchtop Scale Testing of Aerogel Catalysts.</a> SAE Technical Paper 2016-01-920. , (2016).</li><li>Anderson, A. M., Wattley, C. W., Carroll, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silica+Aerogels+Prepared+via+Rapid+Supercritical+Extraction:+Effect+of+Process+Variables+on+Aerogel+Properties.">Silica Aerogels Prepared via Rapid Supercritical Extraction: Effect of Process Variables on Aerogel Properties.</a> J. Non-Cryst. Solids. 355 (2), 101-108 (2009).</li></ol>

作者没有什么可透露的。

本文 RSCE 了催化气凝胶的制备方法和 UCAT 体系的应用。这些协议在其他方法上的主要优势是 RSCE 气凝胶的制造速度和相对便宜的 UCAT 催化试验方法。
要提取的凝胶可以通过多种方法制备, 包括将金属盐浸渍成氧化铝或硅胶湿胶基质, 将金属盐与铝盐作为共同前体, 并将含金属纳米粒子纳入硅胶气凝胶。当湿凝胶毛孔只含酒精和水 (即二氧化硅协议) 时, 不需要溶剂交换。在这种?...

硅和氧化铝基气凝胶具有密度低、孔隙率高、表面面积大、热稳定性好、导热系数低1的特点。这些属性使气凝胶材料具有吸引力的各种应用1,2。利用气凝胶的热稳定性和高表面积的一种应用是异质催化;几篇文章回顾文献在这个区域2,3,4,5。有许多方法来制造气凝胶基催化剂, 包括在硅或氧化铝气凝胶的框架内加入或诱捕催化物种5,6,7, 8,9,10,11。目前的工作重点是通过快速超临界萃取 (RSCE) 和气凝胶材料的催化试验制备汽车污染缓解的协议, 并以含铜气凝胶为例。
三路催化剂 (TWCs) 通常用于汽油机12的污染缓解设备。现代 TWCs 含有铂, 钯和/或铑, 铂族金属 (PGMs) 是罕见的, 因此, 昂贵和环境昂贵的获得。基于更容易获得的金属的催化剂材料将具有显著的经济和环境优势。
气凝胶可以通过湿凝胶制备, 采用多种方法1。目的是避免孔隙坍塌, 因为溶剂从凝胶中除去。本协议所使用的过程是一种快速超临界萃取 (RSCE) 方法, 其中萃取发生在一个金属模具内的凝胶在可编程液压热压机13,14,15, 16。以前在17号议定书中已经证明了使用这一 RSCE 工艺制备二氧化硅气凝胶石柱, 其中强调了与这种方法相关联的相对较短的准备时间。超临界 CO2萃取是一种更常见的方法, 但需要更多的时间, 需要更多的使用溶剂 (包括 CO2) 比 RSCE。其他团体最近发表了一系列协议, 用于制备各种类型的气凝胶, 利用超临界 CO2萃取18,19,20。
本文介绍了各种类型的含铜催化气凝胶的制备和催化试验规程。基于 Kapteijn等对汽车污染缓解有利的条件下碳基金属催化剂的无还原和 CO 氧化活性分级。21、铜被选作这项工作的催化金属。制造方法包括 (a) 铜盐浸渍 (IMP) 成氧化铝或硅胶湿凝胶11, (b) 使用铜 (II) 和铝盐作为共同前体 (co) 时, 制造铜氧化铝气凝胶6,22,(c) 在10制造过程中, 将含铜纳米粒子活捉成二氧化硅气凝胶基质。在每种情况下, RSCE 方法用于从湿凝胶基质13、14、15的毛孔中去除溶剂。
还介绍了利用联合催化试验台 (UCAT)23对这些材料作为汽车污染缓解 TWCs 的适用性的评估协议。UCAT 系统的目的, 其中的关键部分显示在图 1中, 是模拟在一个典型的汽油发动机催化转化器的化学, 热和流动条件。UCAT 函数通过模拟排气混合物在气凝胶样品上的控制温度和流速。气凝胶样品被装入一个2.25 厘米直径的管状填料床流动细胞 ("测试部分"), 其中包含样品在两个屏幕之间。将负载的流动单元放入烤箱中, 以控制废气和催化剂温度, 处理过的排气 (即排气流经填料床) 的样品, 以及未经治疗的气体 (即绕过填料床) 在温度范围内进行检查, 直至700 ˚C。三主要污染物 (CO、NO 和未燃碳氢化合物) 的浓度 (HCs) 是在气凝胶催化剂处理后使用五气体分析仪进行测量的, 并分别在未经治疗的 ("旁路") 流中进行测定;从这些数据中计算出每个污染物的"百分比换算" 。在这里描述的测试, 一个商业上可用的排气混合, 加利福尼亚汽车修理局 (酒吧) 97 低排放混合使用。UCAT 的设计和功能的完整细节在布鲁诺等23中提出。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57075/57075fig1.jpg"> 图1。UCAT 测试部分和取样系统。转载许可从 2016-01-0920 (布鲁诺等。23), 版权所有 2016 SAE 国际。未经 SAE 事先许可, 不允许进一步分发此种材料。<a href="//cloudflare-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/57075/57075fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

<table><tbody><tr><td>Variable micropipettor, 100-1000 &amp;micro;L</td><td>Manufactured by Eppendorf, purchased from Fisher Scientific www.fishersci.com</td><td>S304665</td><td>Any 100-1000 &amp;micro;L pipettor is suitable.</td></tr><tr><td>Variable Pipettor, 2.5-10 mL</td><td>Manufactured by Eppendorf, purchased from Fisher Scientific www.fishersci.com</td><td>21-379-25</td><td>Any variable pipettor is suitable.</td></tr><tr><td>Pasteur pipettes</td><td>FisherScientific</td><td>13-678-6A</td><td></td></tr><tr><td>Syringe</td><td>Purchased from Fisher Scientific</td><td>Z181390 syringe with Z261297 needle</td><td></td></tr><tr><td>Digital balance</td><td>OHaus Explorer Pro</td><td></td><td>Any digital balance is suitable.</td></tr><tr><td>Beakers</td><td>Purchased from Fisher Scientific</td><td></td><td>Any glass beaker is suitable.</td></tr><tr><td>Graduated Cylinder</td><td>Purchased from Fisher Scientific</td><td></td><td>Any glass graduated cylinder is suitable.</td></tr><tr><td>Magnetic Plate/Stirrer</td><td>FisherScientific Isotemp</td><td>SP88854200P</td><td>Any magnetic plate/stirrer is suitable.</td></tr><tr><td>Ultrasonic Cleaner</td><td>FisherScientific FS6</td><td>153356</td><td>Any sonicator is suitable.</td></tr><tr><td>Mold</td><td>Fabricated in House</td><td></td><td>Fabricate from cold-rolled steel or stainless steel.</td></tr><tr><td>Hydraulic Hot Press</td><td>Tetrahedron www.tetrahedronassociates.com</td><td>MTP-14</td><td>Any hot press with temperature and force control will work. Needs maximum temperature of ~550 F and maximum force of 24 tons.</td></tr><tr><td>UCAT (Union Catalytic Testbed)</td><td>Fabricated in House</td><td></td><td>Described in detail in reference #21:&amp;nbsp; Bruno, B.A., Anderson, A.M., Carroll, M.K., Brockmann, P., Swanton, T., Ramphal, I.A., Palace, T. Benchtop Scale Testing of Aerogel Catalysts. SAE Technical Paper 2016-01-920 (2016).</td></tr><tr><td>Bar 97 Gas</td><td>Praxair</td><td>MS_BAR97ZA-D7</td><td></td></tr></tbody></table>

fabrication and testing of catalytic aerogels prepared via rapid supercritical extraction

介绍了将金属种类纳入二氧化硅和氧化铝气凝胶平台制备和测试催化气凝胶的规程。三制备方法: (a) 采用浸渍法将金属盐纳入二氧化硅或氧化铝湿凝胶中;(b) 采用共同前体方法将金属盐纳入氧化铝湿凝胶中;(c) 将金属纳米粒子直接添加到二氧化硅气凝胶前驱体混合物中。该方法利用液压热压机, 可快速 (< 6 小时) 超临界萃取, 结果为低密度气凝胶 (0.10 克/毫升) 和高表面积 (200-800 米2/克)。虽然这里的工作重点是使用铜盐和铜纳米粒子, 该方法可以实施使用其他金属盐和纳米粒子。文中还介绍了用于汽车污染缓解的气凝胶三路催化性能测试协议。这种技术使用定制的设备, 联合催化试验台 (UCAT), 其中模拟排气混合物通过气凝胶样品在控制温度和流速。该系统能够测量催化气凝胶在氧化和还原条件下的能力, 将 co、NO 和未燃烃 (HCs) 转化为较小的有害物种 (co2、H2O 和 N2)。举例说明了气凝胶的催化效果。

图 2显示了产生气凝胶的照相图像。由于湿凝胶在溶剂交换前被分解成块, 铝铜 imp 和硅铜 imp 气凝胶在小而不规则形状的单片中。从这些样品的着色清楚地看出, 气凝胶含有铜种类, 并且在材料中发生铜形态和/或配体结构的变化。铝铜 IMP 气凝胶 (图 2a) 呈红色, 呈绿色-灰色, 颜色为11。铝铜条子气凝胶 (未显示) ?...

Watch this Scientific Journal Video about Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction at JoVE.com

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

在这里, 我们提出了制备和测试催化气凝胶的协议, 将金属种类纳入二氧化硅和氧化铝气凝胶平台。介绍了用铜盐和含铜纳米微粒制备材料的方法。催化试验协议证明了这些气凝胶用于三路催化应用的有效性。

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 ...

fabrication-testing-catalytic-aerogels-prepared-via-rapid

Universidad San Sebastian

Research

JoVE Journal

Chemistry

7.2K 次观看.  Union College. 在这里, 我们提出了制备和测试催化气凝胶的协议, 将金属种类纳入二氧化硅和氧化铝气凝胶平台。介绍了用铜盐和含铜纳米微粒制备材料的方法。催化试验协议证明了这些气凝胶用于三路催化应用的有效性。

视频: Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

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 ...

科研

化学

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

合成和金插在介孔二氧化硅的墙壁催化性能

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml-1, modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 &#197;. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.

Nitrogen is an effective supercritical fluid for extraction or drying processes due to its small molecular size, high density in the near-liquid supercritical regime, and chemical inertness. We present a supercritical nitrogen drying protocol for the purification treatment of reactive, porous materials.

超临界氮处理的活性多孔材料的净化

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

合成和3D纳米石墨烯材料的功能化:石墨烯气凝胶和石墨烯宏组件

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

工程学

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

生物聚合物气凝胶制备使用绿色溶剂

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil (HGO) for production of transportation fuels through a fluid catalytic cracking (FCC) route. Cracking experiments are performed with a fully automated reaction unit at a fixed weight hourly space velocity (WHSV) of 8 hr-1, 490-530 &#176;C, and catalyst/oil ratios of 4-12 g/g. When a feed is in contact with catalyst in the fluid-bed reactor, cracking takes place generating gaseous, liquid, and solid products. The vapor produced is condensed and collected in a liquid receiver at -15 &#176;C. The non-condensable effluent is first directed to a vessel and is sent, after homogenization, to an on-line gas chromatograph (GC) for refinery gas analysis. The coke deposited on the catalyst is determined in situ by burning the spent catalyst in air at high temperatures. Levels of CO2 are measured quantitatively via an infrared (IR) cell, and are converted to coke yield. Liquid samples in the receivers are analyzed by GC for simulated distillation to determine the amounts in different boiling ranges, i.e., IBP-221 &#176;C (gasoline), 221-343 &#176;C (light cycle oil), and 343 &#176;C+ (heavy cycle oil). Cracking of a feed containing canola oil generates water, which appears at the bottom of a liquid receiver and on its inner wall. Recovery of water on the wall is achieved through washing with methanol followed by Karl Fischer titration for water content. Basic results reported include conversion (the portion of the feed converted to gas and liquid product with a boiling point below 221 &#176;C, coke, and water, if present) and yields of dry gas (H2-C2's, CO, and CO2), liquefied petroleum gas (C3-C4), gasoline, light cycle oil, heavy cycle oil, coke, and water, if present.

This paper presents an experimental method to produce biofuels and biochemicals from canola oil mixed with a fossil-based feed in the presence of a catalyst at mild temperatures. Gaseous, liquid, and solid products from a reaction unit are quantified and characterized. Conversion and individual product yields are calculated and reported.

通过催化裂化转换从菜籽油生物燃料和生物化学实验室生产

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

直接溶液还原法快速合成金、钯、铂气凝胶的研究

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

纤维素纳米纤维生物模板复合气凝胶的合成方法

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol&#8211;gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

This procedure describes how to encapsulate cytochrome c (cyt. c) in silica (SiO2) sol-gels, process these gels to form bioaerogels, and use these bioaerogels to rapidly recognize nitric oxide (NO) through a gas-phase reaction. This type of protocol may aid in the future development of biosensors or other bioanalytical devices.

细胞色素封装<em&gt;ç</em&gt;在二氧化硅气凝胶Nanoarchitectures没有金属纳米粒子，同时保持气相生物活性

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are ...

生物工程

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 ...