Sviluppo dei metodi di sintesi per gli aerogel catalitici è stato finanziato mediante concessione di National Science Foundation (NSF) No. DMR-1206631. Progettazione e costruzione di UCAT è stato finanziato mediante concessione di NSF No. CBET-1228851. Finanziamenti supplementari è stato fornito da parte del fondo di ricerca di facoltà College dell'Unione. Gli autori desidera ringraziare anche i contributi di Zachary Tobin, Aude Bechu, Ryan Bouck, Adam Forti e Vinicius Silva.

<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>

Gli autori non hanno nulla a rivelare.

L'utilità del metodo RSCE per la fabbricazione di aerogel catalitico e il sistema UCAT per dimostrare la capacità catalitica è stata dimostrata nel presente documento. Vantaggi principali di questi protocolli rispetto ad altri metodi sono la velocità di fabbricazione aerogel RSCE e l'approccio relativamente poco costoso per prove catalitiche di UCAT.
Gel da estrarre può essere preparato attraverso una varietà di metodi, tra cui impregnazione di sali metallici in un'allumina o silice gel ...

Gli aerogel di silice e allumina-based hanno notevoli proprietà, tra cui densità bassa, alta porosità, alta area superficiale, buona stabilità termica e bassa conducibilità termica1. Queste caratteristiche rendono i materiali aerogel attraente per una varietà di applicazioni1,2. Una applicazione che sfrutta la stabilità termica ed elevata area superficiale dell'aerogel è catalisi eterogenea; vari articoli esaminano la letteratura in questa zona2,3,4,5. Esistono molti approcci alla fabbricazione di catalizzatori a base di aerogel, tra cui incorporazione o allettamento di specie catalitica nel quadro di un silice o allumina aerogel5,6,7, 8,9,10,11. Il presente lavoro si concentra sui protocolli per la preparazione tramite rapida estrazione supercritica (RSCE) e prove catalitiche dei materiali aerogel per la mitigazione dell'inquinamento automobilistico e utilizza rame-contenente aerogel come esempi.
Catalizzatori a tre vie (TWC sono) sono comunemente impiegati nelle apparecchiature di mitigazione dell'inquinamento per benzina motori12. TWC sono moderni contenga platino, Palladio e/o rodio, metalli del gruppo del platino (PGM) che sono rare e, di conseguenza, costosi e ambientalmente costoso da ottenere. Materiali catalizzatori basati su metalli più facilmente disponibili avrebbe significativi vantaggi economici e ambientali.
Gli aerogel possono essere preparati da bagnato Gel utilizzando una varietà di metodi1. L'obiettivo è quello di evitare il collasso dei pori come solvente è rimosso dal gel. Il processo impiegato in questo protocollo è un metodo di estrazione supercritica rapida (RSCE) in cui l'estrazione si verifica da un gel confinato all'interno di uno stampo di metallo in una Pressa oleodinamica a caldo programmabile13,14,15, 16. L'uso di questo processo RSCE per la fabbricazione di monoliti di aerogel di silice è stata dimostrata in precedenza in un protocollo17, in cui il tempo di preparazione relativamente breve connesso con questo approccio è stato sottolineato. Supercritica CO2 estrazione è un approccio più comune, ma richiede più tempo e maggiore utilizzo di solventi (comprese le CO2) rispetto RSCE. Altri gruppi hanno recentemente pubblicato i protocolli per la preparazione di una varietà di tipi di aerogel che utilizzano supercritici CO2 estrazione18,19,20.
Qui, protocolli per fabbricare e cataliticamente testing di una varietà di tipi di aerogel catalitici contenenti rame sono presentati. Basato sulla riduzione di NO e CO ossidazione attività classifica dei catalizzatori di metalli di base supportate da carbonio sotto condizioni di interesse alla mitigazione dell'inquinamento automobilistico fornito da Metz et al. 21, rame è stato selezionato come il metallo catalitico per questo lavoro. Approcci di fabbricazione includono (a) impregnazione (IMP) di sali di rame in allumina o silice gel bagnato11, (b) utilizzo di sali di alluminio e rame (II) come co-precursori (Co-P) quando fabbricando gli aerogel di allumina rame6,22, e (c) intrappolare rame-contenente nanoparticelle in una matrice di aerogel di silice durante la fabbricazione10. In ogni caso, un metodo RSCE viene utilizzato per la rimozione del solvente dai pori del bagnato gel matrice13,14,15.
Un protocollo per la valutazione dell'idoneità di questi materiali come TWC sono per la mitigazione dell'inquinamento automobilistico, utilizzando il Testbed catalitica dell'Unione (UCAT)23, inoltre è presentato. Lo scopo del sistema UCAT, parti principali di cui sono schematicamente in Figura 1, è quello di simulare la chimica, termica e sperimentate in un convertitore catalitico a motore benzina tipiche condizioni di flusso. Funzioni UCAT passando una miscela di scarico simulato su un campione di aerogel ad un tasso di flusso e temperatura controllato. Il campione di aerogel viene caricato in un flusso di 2,25 cm-diametro base imballata tubolare cellula (sezione di test""), che contiene il campione tra i due schermi. La cella di flusso caricato viene inserita in un forno per il controllo del gas di scarico, temperatura del catalizzatore e campioni di gas di scarico trattata (cioè scarico attraversato nella base imballata) e gas non trattati (cioè bypassando nella base imballata) vengono esaminate a una gamma di temperature fino a 700 ˚C. Le concentrazioni delle tre principali inquinanti - CO, NO, e gli idrocarburi incombusti (HCs) - sono misurati utilizzando un analizzatore di gas di cinque dopo essere stati trattati per il catalizzatore di aerogel e, separatamente, in un non trattato flusso (by-pass""); da questi dati viene calcolata la conversione percentuale "" per ciascun inquinante. Per il test descritto nel presente documento, si fondono uno scarico commercialmente disponibile, basse emissioni Bureau California di riparazione automobilistica (BAR) 97 blend è stato impiegato. Dettagli completi di UCAT's design e funzionamento sono presentati in Bruno et al.23
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57075/57075fig1.jpg"> Figura 1. Sezione Test UCAT e sistemi di campionamento. Ristampato con il permesso dal 2016-01-0920 (Bruno et al. 23), copyright 2016 SAE International. Ulteriore distribuzione di questo materiale non è consentito senza previa autorizzazione da SAE. <a href="//cloudflare.jove.com/files/ftp_upload/57075/57075fig1large.jpg" target="_blank">Clicca qui per visualizzare una versione più grande di questa figura.</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

Protocolli per la preparazione e test catalitica aerogels incorporando specie metalliche nelle piattaforme di aerogel di silice e allumina sono presentati. Vengono descritti tre metodi di preparazione: (a) l'incorporazione di metallo sali in silice o allumina gel bagnato utilizzando un metodo di impregnazione; (b) l'incorporazione di metallo sali in gel bagnato di allumina utilizzando un metodo di co-precursore; e (c) l'aggiunta di nanoparticelle metalliche direttamente in una miscela di precursore aerogel di silice. I metodi utilizzano una Pressa oleodinamica a caldo, che permette per una rapida (< 6h) estrazione supercritica e risultati in aerogel di densità bassa (0,10 g/mL) e ad alta area superficiale (200-800 m2/g). Mentre il lavoro qui presentato si concentra sull'uso di sali di rame e rame nanoparticelle, l'approccio può essere implementato utilizzando altri sali metallici e nanoparticelle. Un protocollo per testare la capacità catalitica a tre vie di questi aerogel per la mitigazione dell'inquinamento automobilistico inoltre è presentato. Questa tecnica utilizza attrezzature su misura, il Testbed catalitica dell'Unione (UCAT), in cui una miscela di scarico simulato viene passata sopra un campione di aerogel a una temperatura controllata e portata. Il sistema è in grado di misurare la capacità di aerogel catalitica, in entrambi ossidanti e ridurre condizioni, per convertire CO, NO e non bruciato idrocarburi (HCs) a meno specie dannose (CO2, H2O e N2). Esempio catalitiche risultati sono presentati per l'aerogel descritto.

Immagini fotografiche dell'aerogel risultante sono presentati nella Figura 2. Perché il gel bagnato sono stati suddivisi in pezzi prima del cambio solvente, l'aerogel Al-Cu IMP e IMP Si-Cu sono in piccoli, di forma irregolare pezzi monolitici. È chiaro dalla colorazione di questi campioni contenenti l'aerogel rame specie e che variazioni nella struttura di speciazione e/o legante rame si verificano all'interno dei materiali. Al-Cu IMP aerogel (<strong class...

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

Qui presentiamo i protocolli per la preparazione e test catalitica aerogels incorporando specie metalliche nelle piattaforme di aerogel di silice e allumina. Metodi per la preparazione di materiali usando sali di rame e rame-contenente nanoparticelle sono presenti. Catalitica dei protocolli dei test dimostrano l'efficacia di questi aerogel per applicazioni di catalisi di tre vie.

Fabbricazione e collaudo di aerogel catalitico preparato tramite rapida estrazione supercritica

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 de Cartagena UDEC

Research

JoVE Journal

Chemistry

7.2K Views.  Union College. Qui presentiamo i protocolli per la preparazione e test catalitica aerogels incorporando specie metalliche nelle piattaforme di aerogel di silice e allumina. Metodi per la preparazione di materiali usando sali di rame e rame-contenente nanoparticelle sono presenti. Catalitica dei protocolli dei test dimostrano l'efficacia di questi aerogel per applicazioni di catalisi di tre vie.

Video: 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.

Preparazione Silica Aerogel Monoliti tramite una rapida supercritica metodo di estrazione

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

Ricerca

Chimica

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.

Sintesi e prestazioni catalitica dell&#39;oro intercalata nelle Mura di mesoporosi silice

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.

Elaborazione azoto supercritica per la purificazione di reattivi materiali porosi

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.

Sintesi e funzionalizzazione di 3D Materials Nano-grafene: grafene Aerogels e grafene Assemblee Macro

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

Ingegneria

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.

Preparazione del biopolimero Aerogels che utilizzano solventi verdi

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.

Laboratorio produzione di biocarburanti e biochimici da un olio di colza attraverso cracking catalitico di conversione

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.

Un metodo di sintesi rapida per Au, Pd e Pt Aerogels tramite riduzione diretta basata su soluzione

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.

Metodo di sintesi per Cellulosa Nanofiber Biotemplated Palladium Composite Aerogels

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.

incapsulante citocromo<em&gt; c</em&gt; In Silica Aerogel nanoarchitetture senza metallo nanoparticelle, pur mantenendo bioattività gas-phase

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

Bioingegneria

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.

Aerogel di silice esteticamente migliorato tramite incorporazione di incisioni e coloranti laser

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

Fabbricazione e collaudo di aerogel catalitico preparato tramite rapida estrazione supercritica

Riepilogo

Esplora Altri Video

Capitoli in questo video