Name: temperature-programmed deoxygenation of acetic acid on molybdenum carbide catalysts
Uploaded: 2017-02-07T15:00:00
Description: Watch this Scientific Journal Video about Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts at JoVE.com

This work was supported by the Department of Energy Bioenergy Technologies Office under Contract no. DE-AC36-08-GO28308. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

CAUTION: Consult safety data sheets (SDS) for all chemicals used prior to operation. Flammable gases may present explosion hazards if combined with air or oxygen and an ignition source. Hydrogen is an extremely flammable gas. Acids are corrosive, and in the case of skin or eye contact, are irritants and may produce burns. Acetic acid is a flammable liquid and vapor and thus may ignite and/or explode in the presence of open flames, sparks and oxidizing agents, in addition to potentially causing severe skin burns and eye d...

<ol>
	<li>Cvetanovi&#263;, R. J., Amenomiya, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+a+Temperature-Programmed+Desorption+Technique+to+Catalyst+Studies.">Application of a Temperature-Programmed Desorption Technique to Catalyst Studies.</a> Adv. Catal. 17, 103-149 (1967).</li><li>Falconer, J. L., Schwarz, 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=Temperature-Programmed+Desorption+and+Reaction:+Applications+to+Supported+Catalysts.">Temperature-Programmed Desorption and Reaction: Applications to Supported Catalysts.</a> Catal. Rev. - Sci. Eng. 25 (2), 141-227 (1983).</li><li>Hurst, N. W., Gentry, S. J., Jones, A., McNicol, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+Programmed+Reduction.">Temperature Programmed Reduction.</a> Catal. Rev. - Sci. Eng. 24 (2), 233-309 (1982).</li><li>Sanchez, A., 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=When+Gold+Is+Not+Noble:+Nanoscale+Gold+Catalysts.">When Gold Is Not Noble: Nanoscale Gold Catalysts.</a> J. Phys. Chem. A. 103 (48), 9573-9578 (1999).</li><li>Alayoglu, S., Nilekar, A. U., Mavrikakis, M., Eichhorn, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ru-Pt+core-shell+nanoparticles+for+preferential+oxidation+of+carbon+monoxide+in+hydrogen.">Ru-Pt core-shell nanoparticles for preferential oxidation of carbon monoxide in hydrogen.</a> Nat Mater. 7 (4), 333-338 (2008).</li><li>Wachs, I. E., Madix, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+oxidation+of+methanol+on+a+silver+(110)+catalyst.">The oxidation of methanol on a silver (110) catalyst.</a> Surf. Sci. 76 (2), 531-558 (1978).</li><li>Topsoe, N. Y., Topsoe, H., Dumesic, 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=Vanadia/Titania+Catalysts+for+Selective+Catalytic+Reduction+(SCR)+of+Nitric-Oxide+by+Ammonia.">Vanadia/Titania Catalysts for Selective Catalytic Reduction (SCR) of Nitric-Oxide by Ammonia.</a> J Catal. 151 (1), 226-240 (1995).</li><li>Clarke, D. B., Bell, A. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Infrared+Study+of+Methanol+Synthesis+from+CO2+on+Clean+and+Potassium-Promoted+Cu/SiO2.">An Infrared Study of Methanol Synthesis from CO2 on Clean and Potassium-Promoted Cu/SiO2.</a> J Catal. 154 (2), 314-328 (1995).</li><li>Schaidle, J. A., 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=Experimental+and+Computational+Investigation+of+Acetic+Acid+Deoxygenation+over+Oxophilic+Molybdenum+Carbide:+Surface+Chemistry+and+Active+Site+Identity.">Experimental and Computational Investigation of Acetic Acid Deoxygenation over Oxophilic Molybdenum Carbide: Surface Chemistry and Active Site Identity.</a> ACS Catal. 6 (2), 1181-1197 (2016).</li><li>Ruddy, D. A., 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+heterogeneous+catalysts+for+bio-oil+upgrading+via+"ex+situ+catalytic+fast+pyrolysis":+catalyst+development+through+the+study+of+model+compounds.">Recent advances in heterogeneous catalysts for bio-oil upgrading via "ex situ catalytic fast pyrolysis": catalyst development through the study of model compounds.</a> Green Chem. 16 (2), 454-490 (2014).</li><li>Dutta, A., Schaidle, J. A., Humbird, D., Baddour, F. G., Sahir, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conceptual+Process+Design+and+Techno-Economic+Assessment+of+Ex+Situ+Catalytic+Fast+Pyrolysis+of+Biomass:+A+Fixed+Bed+Reactor+Implementation+Scenario+for+Future+Feasibility.">Conceptual Process Design and Techno-Economic Assessment of Ex Situ Catalytic Fast Pyrolysis of Biomass: A Fixed Bed Reactor Implementation Scenario for Future Feasibility.</a> Top. Catal. 59 (1), 2-18 (2016).</li><li>Venkatakrishnan, V. K., Delgass, W. N., Ribeiro, F. H., Agrawal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxygen+removal+from+intact+biomass+to+produce+liquid+fuel+range+hydrocarbons+via+fast-hydropyrolysis+and+vapor-phase+catalytic+hydrodeoxygenation.">Oxygen removal from intact biomass to produce liquid fuel range hydrocarbons via fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation.</a> Green Chem. 17 (1), 178-183 (2015).</li><li>Bej, S. K., Thompson, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acetone+condensation+over+molybdenum+nitride+and+carbide+catalysts.">Acetone condensation over molybdenum nitride and carbide catalysts.</a> Appl. Catal., A. 264 (2), 141-150 (2004).</li><li>Sullivan, M. M., Held, J. T., Bhan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+site+evolution+of+molybdenum+carbide+catalysts+upon+exposure+to+oxygen.">Structure and site evolution of molybdenum carbide catalysts upon exposure to oxygen.</a> J Catal. 326, 82-91 (2015).</li><li>Lee, W. S., Kumar, A., Wang, Z. S., Bhan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+Titration+and+Transient+Kinetic+Studies+of+Site+Requirements+in+Mo2C-Catalyzed+Vapor+Phase+Anisole+Hydrodeoxygenation.">Chemical Titration and Transient Kinetic Studies of Site Requirements in Mo2C-Catalyzed Vapor Phase Anisole Hydrodeoxygenation.</a> ACS Catal. 5 (7), 4104-4114 (2015).</li><li>Ren, H., 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=Selective+Hydrodeoxygenation+of+Biomass-Derived+Oxygenates+to+Unsaturated+Hydrocarbons+using+Molybdenum+Carbide+Catalysts.">Selective Hydrodeoxygenation of Biomass-Derived Oxygenates to Unsaturated Hydrocarbons using Molybdenum Carbide Catalysts.</a> Chemsuschem. 6 (5), 798-801 (2013).</li><li>Grob, R. L., Kaiser, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Modern Practice of Gas Chromatography. , 403-460 (2004).</li><li>Guiochon Georges, L., Guillemin Claude, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Journal of Chromatography Library. 42, 563-586 (1988).</li><li>Guiochon Georges, L., Guillemin Claude, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Journal of Chromatography Library. 42, 587-627 (1988).</li><li>Guiochon Georges, L., Guillemin Claude, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Journal of Chromatography Library. 42, 629-659 (1988).</li><li>Guiochon Georges, L., Guillemin Claude, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Journal of Chromatography Library. 42, 661-687 (1988).</li><li>Baddour, F. G., Nash, C. P., Schaidle, J. A., Ruddy, D. A. <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+&#945;-MoC1-x+Nanoparticles+with+a+Surface-Modified+SBA-15+Hard+Template:+Determination+of+Structure-Function+Relationships+in+Acetic+Acid+Deoxygenation.">Synthesis of &#945;-MoC1-x Nanoparticles with a Surface-Modified SBA-15 Hard Template: Determination of Structure-Function Relationships in Acetic Acid Deoxygenation.</a> Angew. Chem., Int. Ed. n/a-n/a. , (2016).</li><li>Habas, S. E., 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=A+Facile+Molecular+Precursor+Route+to+Metal+Phosphide+Nanoparticles+and+Their+Evaluation+as+Hydrodeoxygenation+Catalysts.">A Facile Molecular Precursor Route to Metal Phosphide Nanoparticles and Their Evaluation as Hydrodeoxygenation Catalysts.</a> Chem. Mater. 27 (22), 7580-7592 (2015).</li><li>Zhang, Q., 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=Deconvolution+and+quantification+of+hydrocarbon-like+and+oxygenated+organic+aerosols+based+on+aerosol+mass+spectrometry.">Deconvolution and quantification of hydrocarbon-like and oxygenated organic aerosols based on aerosol mass spectrometry.</a> Environ Sci Technol. 39 (13), 4938-4952 (2005).</li><li>Ko, E. I., Benziger, J. B., Madix, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactions+of+Methanol+on+W(100)+and+W(100)-(5+X+1)C+Surfaces.">Reactions of Methanol on W(100) and W(100)-(5 X 1)C Surfaces.</a> J Catal. 62 (2), 264-274 (1980).</li><li>Pestman, R., Koster, R. M., Pieterse, J. A. Z., Ponec, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactions+of+carboxylic+acids+on+oxides:+1.+Selective+hydrogenation+of+acetic+acid+to+acetaldehyde.">Reactions of carboxylic acids on oxides: 1. Selective hydrogenation of acetic acid to acetaldehyde.</a> J Catal. 168 (2), 255-264 (1997).</li><li>Pestman, R., Koster, R. M., Van Duijne, A., Pieterse, J. A. Z., Ponec, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactions+of+carboxylic+acids+on+oxides:+2.+Bimolecular+reaction+of+aliphatic+acids+to+ketones.">Reactions of carboxylic acids on oxides: 2. Bimolecular reaction of aliphatic acids to ketones.</a> J Catal. 168 (2), 265-272 (1997).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NIST+Standard+Reference+Database+Number+69.">NIST Standard Reference Database Number 69.</a> NIST Chemistry WebBook. , (2016).</li><li>Ausloos, P., 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=The+critical+evaluation+of+a+comprehensive+mass+spectral+library.">The critical evaluation of a comprehensive mass spectral library.</a> J. Am. Soc. Mass Spectrom. 10 (4), 287-299 (1999).</li><li>Barwick, V., Langley, J., Mallet, T., Stein, B., Webb, 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> Best Practice Guide for Generating Mass Spectra. , (2006).</li><li>Lecchi, P., 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=A+Method+for+Monitoring+and+Controlling+Reproducibility+of+Intensity+Data+in+Complex+Electrospray+Mass+Spectra:+A+Thermometer+Ion-based+Strategy.">A Method for Monitoring and Controlling Reproducibility of Intensity Data in Complex Electrospray Mass Spectra: A Thermometer Ion-based Strategy.</a> J. Am. Soc. Mass Spectrom. 20 (3), 398-410 (2009).</li></ol>

The TPRxn method is a powerful tool for screening of catalytic materials, providing information about the activity and selectivity of a catalyst as a function of reaction temperature. Other temperature-programmed methods such as TPD, TPO and TPR can provide information on the adsorption strength of reactants, number of adsorption sites, and appropriate catalyst pre-treatment procedures, but do not provide direct catalytic performance data. It is important to note that the TPRxn method detailed in this work does not measu...

Temperature programmed reaction (TPRxn) is one of many temperature programmed methods, including desorption (TPD), oxidation (TPO), and reduction (TPR), and proceeds via exposure of a catalyst to a reactant concurrent with or followed by a steady increase in temperature.1,2,3 TPRxn is a transient technique that provides information about catalyst activity and selectivity as a function of reaction temperature.4,5,6 It is also a popular technique: a search of the keywords &#39;temperature programmed reaction&#39; in the literature yields over 1,000 sources citing its use.
TPRxn experiments are typically performed in a microreactor system, equipped with a mass spectrometer (MS) for real-time analysis of the reactor effluent and correlation of performance with temperature. Reactant gases can be introduced using mass flow controllers and liquids can be introduced via a syringe pump or as vapors by bubbling inert gas through a liquid. The catalyst is often pre-treated in situ to form the desired catalytic phase for the reaction. Some systems are equipped with additional analytical equipment, beyond the typical mass spectrometer, to provide quantitative or qualitative information about the catalyst selectivity, surface species present on the catalyst, or reaction mechanism. For example, temperature programmed in situ Fourier Transform Infrared Spectroscopy (FTIR) provides information about the evolution of surface species with varying reaction temperature.7,8 The TPRxn system demonstrated in this work is equipped with a gas chromatogram (GC) in addition to the more typical MS. This GC, equipped with four parallel columns, allows for more accurate quantification of the reaction products, but is limited in analysis frequency by the time it takes the products to elute through the columns. Thus, the combination of MS and GC can be particularly useful for coupling real-time identification with accurate quantification of reactants and products.
Here, we apply the TPRxn methodology to study the deoxygenation of acetic acid on molybdenum carbide catalysts. This is an interesting and important reaction in catalyst research, as acetic acid is a useful analog for the many carboxylic acids present in biomass pyrolysis vapors.9 The high oxygen content in biomass pyrolysis vapors necessitates oxygen removal to produce hydrocarbon fuels,10,11,12 and molybdenum carbide catalysts have shown promising deoxygenation performance for many biomass pyrolysis vapor model compounds, including furfural, 1-propanol, phenolics and acetic acid.9,13,14,15,16 However, the activity and selectivity of molybdenum carbide catalysts in deoxygenation reactions is dependent on the catalyst structure and composition, the reacting species and the reaction conditions.
The data collected from TPRxn of acetic acid shows that molybdenum carbide catalysts are active for deoxygenation reactions above ca. 300 &#176;C, and when combined with catalyst characterization information allows for quantification of the catalyst activity as a function of temperature via the calculation of acetic acid turnover rates. The TPRxn results show that deoxygenation (i.e., C-O bond-breaking) products are favored at temperatures below ca. 400 &#176;C and decarbonylation (i.e., C-C bond-breaking) products are favored at temperatures above ca. 400 &#176;C. Additionally, TPRxn studies illustrate the changes in the activity and selectivity of molybdenum carbide catalysts produced using various synthetic procedures (i.e., the production of different molybdenum carbide catalyst structures and compositions). Still, the value of this information and, more generally, the successful application of TPRxn experimental data toward catalyst design and process optimization is a function of the quality of the data obtained. Careful consideration and knowledge of the potential difficulties and limitations highlighted throughout the TPRxn procedure is paramount.

<table border="0" cellpadding="0" cellspacing="0" width="942">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">glacial acetic acid</td>
			<td style="width:179px;">Cole-Parmer</td>
			<td style="width:148px;">EW-88401-62</td>
			<td style="width:401px;">alternate supplier acceptable if ACS purity grade. See caution statement in protocol for safety information</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">UHP H&#8322;</td>
			<td style="width:179px;">Airgas</td>
			<td style="width:148px;">HY R300</td>
			<td>alternate supplier acceptable if &#62;99.99% purity</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">UHP He</td>
			<td style="width:179px;">Airgas</td>
			<td style="width:148px;">HE R300SS</td>
			<td>alternate supplier acceptable if &#62;99.99% purity</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">UHP Ar</td>
			<td style="width:179px;">Arigas</td>
			<td style="width:148px;">AR R200</td>
			<td>alternate supplier acceptable if &#62;99.99% purity</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">acetone</td>
			<td style="width:179px;">VWR International</td>
			<td style="width:148px;">BDH1101-4LP</td>
			<td>alternate supplier acceptable if &#62;99.5% purity</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">quartz chips</td>
			<td style="width:179px;">Powder Technology Inc.</td>
			<td style="width:148px;">Crushed Quartz</td>
			<td style="width:401px;">sieved 180-300 &#181;m, calcined in air at 500 &#176;C overnight</td>
		</tr>
		<tr height="56">
			<td height="56" style="height:56px;width:215px;">mass spectrometer - turbo vacuum pump</td>
			<td style="width:179px;">Pfeiffer Vacuum</td>
			<td style="width:148px;">TSU 071</td>
			<td style="width:401px;">mass spectrometer is controlled with LabVIEW 2010 software package (National Instruments)</td>
		</tr>
		<tr height="56">
			<td height="56" style="height:56px;width:215px;">mass spectrometer - turbo vacuum pump</td>
			<td style="width:179px;">Stanford Research Systems</td>
			<td style="width:148px;">RGA100</td>
			<td style="width:401px;"></td>
		</tr>
		<tr height="126">
			<td height="126" style="height:126px;width:215px;">micro gas chromatograph</td>
			<td style="width:179px;">Agilent</td>
			<td style="width:148px;">CP740388</td>
			<td style="width:401px;">490 Micro GC; 4-channel system 
			Channel 1: 494001360 Molseive 10m, heated backflush 
			Channel 2: 494001460 PPU 10m, heated backflush 
			Channel 3: 490040 AL2O3/KCL 10+0.2m, heated backflush SPECIAL 
			Channel 4: 492005750 5CB 15m, heated</td>
		</tr>
		<tr height="56">
			<td height="56" style="height:56px;width:215px;">GC software</td>
			<td style="width:179px;">Aglient</td>
			<td style="width:148px;">OpenLAB CDS EZChrom Edition</td>
			<td style="width:401px;"></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">clean gas filters</td>
			<td style="width:179px;">Agilent</td>
			<td style="width:148px;">CP17974</td>
			<td>for use on GC carrier gases (He, Ar)</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">quartz &#34;U-tube&#34; reactor</td>
			<td style="width:179px;">n/a</td>
			<td style="width:148px;"></td>
			<td>hand blown glass, custom built to order</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">bubbler</td>
			<td style="width:179px;">n/a</td>
			<td style="width:148px;"></td>
			<td>custom built to order</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">ceramic furnace</td>
			<td style="width:179px;">Watlow</td>
			<td style="width:148px;">discontinued</td>
			<td>Similar furnace part #: VC401J12A-B000R</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">heat tape controller</td>
			<td style="width:179px;">n/a</td>
			<td style="width:148px;"></td>
			<td>custom built with Watlow EZ-zone parts</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">heat tape</td>
			<td style="width:179px;">Omega</td>
			<td style="width:148px;">FGH051-060</td>
			<td style="width:401px;">alternate supplier for extreme temperature heat tape acceptable</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">heat tape insulation</td>
			<td style="width:179px;">JEGS</td>
			<td style="width:148px;">710-80809</td>
			<td>alternate supplier acceptable</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">thermocouple</td>
			<td style="width:179px;">Omega</td>
			<td style="width:148px;">e.g., KMQSS-062U-18</td>
			<td>K-type thermocouples; alternate sizes may be required</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">thermocouple o-ring</td>
			<td style="width:179px;">Swagelok</td>
			<td style="width:148px;">VT-7-OR-001-1/2</td>
			<td>perfluoroelastomer(fluorocarbon FKM) o-ring</td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">2 &#181;m solids filter, VCR gasket</td>
			<td style="width:179px;">Swagelok</td>
			<td style="width:148px;">SS-4-VCR-2-2M</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:58px;width:215px;">1 &#181;m orifice, VCR gasket</td>
			<td style="width:179px;">Lenox Laser</td>
			<td style="width:148px;">SS-4-VCR-2</td>
			<td>for mass spectrometer orifice</td>
		</tr>
		<tr height="93">
			<td height="93" style="height:94px;width:215px;">316/316L stainless steel tubing and fittings</td>
			<td style="width:179px;">Swagelok</td>
			<td style="width:148px;">Varies</td>
			<td style="width:401px;">See Swagelok &#39;VCR Metal Gasket Face Seal Fittings&#39; and &#39;Stainless Steel Seamless Tubing and Tube Support Systems&#39; catalogs for more information</td>
		</tr>
		<tr height="93">
			<td height="93" style="height:94px;width:215px;">316/316L stainless steel tubing and fittings</td>
			<td style="width:179px;">Swagelok</td>
			<td style="width:148px;">Varies</td>
			<td style="width:401px;">See Swagelok &#39;Integral-Bonnet Needle Valves&#39;, &#39;Bellows-Sealed Valves&#39; and &#39;One-Piece Instrumentation Ball Valves&#39; catalogs for more information</td>
		</tr>
	</tbody>
</table>

temperature-programmed deoxygenation of acetic acid on molybdenum carbide catalysts

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system includes a reactor, furnace, gas and vapor sources, flow control, instrumentation to quantify reaction products (e.g., gas chromatograph), and instrumentation to monitor the reaction in real time (e.g., mass spectrometer). Here, we apply the TPRxn methodology to study molybdenum carbide catalysts for the deoxygenation of acetic acid, an important reaction among many in the upgrading/stabilization of biomass pyrolysis vapors. TPRxn is used to evaluate catalyst activity and selectivity and to test hypothetical reaction pathways (e.g., decarbonylation, ketonization, and hydrogenation). The results of the TPRxn study of acetic acid deoxygenation show that molybdenum carbide is an active catalyst for this reaction at temperatures above ca. 300 &#176;C and that the reaction favors deoxygenation (i.e., C-O bond-breaking) products at temperatures below ca. 400 &#176;C and decarbonylation (i.e., C-C bond-breaking) products at temperatures above ca. 400 &#176;C.

The online MS provides the capability to analyze the gas composition at the reactor outlet in real-time. The online MS is not coupled with any device to separate products prior to analysis, and thus species identification is challenging when differentiating between compounds with overlapping mass fragmentation patterns. As shown in Table 2, many of the common products from acetic acid TPRxn experiments are characterized by multiple common m/z signals. Deconvolution of the...

Watch this Scientific Journal Video about Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts at JoVE.com

Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts

Presented here is a protocol for the operation of a micro-scale temperature-programmed reactor for evaluating the catalytic performance of molybdenum carbide during acetic acid deoxygenation.

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system ...

The overall goal of this temperature-programmed reaction method is to determine the deoxygenation performance of molybdenum carbide catalyst from the pyrolysis oil model compound acetic acid. This method can help answer key questions in the field of vapor phase upgrading using heterogeneous catalysts, such as those regarding catalytic activity and selectivity from pyrolysis oil model compounds. The main advantages of this technique is the ability to test catalytic performance over a range of temperatures in a single experiment.While this method could provide insight into catalytic performance with acetic acid vapors, it can also be applied to other pyrolysis oil model compounds such as acid aldehyde, ethanol, methanol, and anisole. First, remove a clean, dry quartz U-tube reactor from a drying oven. Once the reactor has cooled to room temperature, load a small amount of quartz wool into it using the minimum amount needed to support the catalyst bed.Using a clean, stiff metal wire packing word, gently push the wool down the quartz tube to the end of the straight section. Next, mix 50 milligrams of molybdenum carbide catalyst with 200 milligrams of sieved calcined quartz chips to prevent channeling and to ensure consistent temperature through the catalyst bed. Using weigh paper and a clean funnel, pour the catalyst and quartz chip mixture into the reactor such that the catalyst bed sits on top of the quartz wool support.Then, gently push a second small piece of quartz wool on top of the catalyst bed, securing the catalyst bed in place. It's important to ensure that the catalyst-quartz chip mixture is homogenous. Inhomogeneous mixtures can lead to channeling, temperature gradients, and an excessive pressure drop across the catalyst bed.Install the reactor by first connecting and tightening the fitting on the upstream side of the catalyst bed, which is the straight section of the reactor tube. Then, connect and tighten the fitting on the downstream side of the catalyst bed. Next, adjust the reactor thermocouple position by pushing the thermocouple through a bored-through fitting so that the tip of the thermocouple sits on the top edge of the catalyst bed.Install insulation around the upper section of the reactor, and then carefully raise the furnace to the highest level allowed by the U-tube reactor such that the top edge of the furnace does not touch the reactor. Begin purging the system by flowing ultra-high purity helium at 40 sccm through the calibrated mass flow controller, or MFC. Following this, open the mass spectrometer, or MS orifice valve, to allow gas to reach the MS ion source.After opening the hydrogen tank cylinder and regulator needle valves, begin flowing ultra-high purity hydrogen, but opening the system line shutoff valve immediately downstream of the hydrogen MFC and setting the MFC to flow at 1.3 sccm. Then, adjust the helium flow to 36 sccm, such that the gas mixture is 3.5%hydrogen. Once the hydrogen and helium gas phase concentrations have stabilized, enter the temperature program into the furnace controller, then begin the temperature program.For the temperature-programmed reaction, begin the flow of acetic acid vapors through the reactor by opening the inlet and outlet saturator valves and subsequently closing the saturator bypass valve. Route the gas flow to the microgas chromatograph, or micro GC, by switching the three-way valve downstream of the reactor to the micro GC position. After allowing the system pressure of acetic acid gas phase concentration to stabilize, program the furnace temperature controller to ramp from room temperature to 600 degrees Celsius at ten degrees Celsius per minute.Now begin collecting micro GC samples as frequently as possible. Begin the temperature program immediately after starting to collect the micro GC samples. When the temperature program has completed, stop the micro GC samples.Using the computer software associated with the MS, turn the MS ion source off, then close the one micrometer MS orifice valve. After the last micro GC sample has completed, load a method that sets the column temperatures to the maximum allowable limit as recommended by the manufacturer. Shut off the hydrogen flow by setting the hydrogen MFC to zero sccm and closing the hydrogen shutoff valve.Shut off the flow of acetic acid vapors to the reactor by opening the saturator bypass valve and closing the inlet and outlet saturator valves. After allowing the reactor to cool to ambient temperature, turn off the helium flow by setting the helium MFC to zero sccm, then close the shutoff valve located immediately downstream of the helium MFC. Once the system has reached ambient pressure, route the gas to the local exhaust ventilation using the three-way valve.Uninstall the reactor by first disconnecting the fitting on the downstream side of the reactor, which is the fitting connected to the flexible stainless steel tubing. Finally, disconnect the fitting on the upstream side of the reactor. As shown here, many of the common products from acetic acid temperature-programmed reaction experiments are characterized by common mass to charge signals in mass spectrometry, and thus signal deconvolution is required.Following deconvolution, the normalized and corrected MS data maybe used semiquantitatively to gather information, such as reactive conversion and relative product concentration as a function of reaction temperature. Representative data from a study comparing the deoxygenation performance of several molybdenum carbide catalysts in an acetic acid temperature-programmed reaction is shown here. A templated nanoparticle molybdenum carbide catalyst demonstrated greater acetic acid turnover rate compared to its untemplated counterpart in similar acetic acid turnover rates compared to the bulk molybdenum carbide catalysts below 400 degrees Celsius.Above 400 degrees Celsius, the templated catalysts demonstrated a greater acetic acid turnover rate than any of the other catalysts studied. The hydrogen turnover rates were lower in the nanoparticle catalysts than on the bulk catalysts at all temperatures. Both nanoparticle materials demonstrated higher selectivity to ketonization products above 400 degrees Celsius than their bulk counterparts, which was attributed to an increase in the fraction of strong acid sites relative to the bulk materials.Furthermore, the ratio of acid sites to hydrogen activation sites was identified as a key property in determining acetic acid deoxygenation performance. This technique can be performed in less than four hours, which makes the temperature-programmed reaction method an effective tool for screening the performance of catalytic materials and their various reaction conditions. After watching this video, you should have a good understanding of how to safely and effectively operate a temperature-programmed reaction using acetic acid vapors.

temperature-programmed-deoxygenation-acetic-acid-on-molybdenum

Research

Education

JoVE Journal

JoVE Core

Organic Chemistry

Chemistry

Unit 1

Thermodynamics and Chemical Kinetics

SCIENTISTS IN ACTION

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 ...

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.

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

Reverse Microemulsion-mediated Synthesis of Monometallic and Bimetallic Early Transition Metal Carbide and Nitride Nanoparticles

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The silica-encapsulated metal oxide nanoparticles are then carburized in a methane/hydrogen atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal carbide nanoparticles. During the carburization process, the silica shells prevent the sintering of adjacent carbide nanoparticles while also preventing the deposition of excess surface carbon. Alternatively, the silica-encapsulated metal oxide nanoparticles can be nitridized in an ammonia atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal nitride nanoparticles. By adjusting the reverse microemulsion parameters, the thickness of the silica shells, and the carburization/nitridation conditions, the transition metal carbide or nitride nanoparticles can be tuned to various sizes, compositions, and crystal phases. After carburization or nitridation, the silica shells are then removed using either a room-temperature aqueous ammonium bifluoride solution or a 0.1 to 0.5 M NaOH solution at 40-60 &#176;C. While the silica shells are dissolving, a high surface area support, such as carbon black, can be added to these solutions to obtain supported early transition metal carbide or nitride nanoparticles. If no high surface area support is added, then the nanoparticles can be stored as a nanodispersion or centrifuged to obtain a nanopowder.

A &#8220;removable ceramic coating method&#8221; is presented in visual format for the synthesis of non-sintered and metal-terminated monometallic and bimetallic early transition metal carbide and nitride nanoparticles with tunable sizes and crystal structures.

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The ...

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are demonstrated here. The catalyst forms a substitutional solid solution structure, with a small and uniform particle size around 2 nm. This is realized by careful control over the impregnation, calcination, and reduction steps during catalyst preparation and is identified by advanced in situ synchrotron techniques. The catalyst propane dehydrogenation performance continuously improves with increasing Cu:Pt atomic ratio.

A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are ...

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants. Low toxic sodium hypophosphite was chosen as the phosphorus source to react with olefin A (2,3-dimethyl-1-butene) to generate a monoalkylphosphinic acid intermediate. Amantadine was adopted to remove the dialkylphosphinic acid byproduct, as only the monoalkylphosphinic acid can react with amantadine to form an amantadine&#8729;mono-alkylphosphinic acid salt, while the dialkylphosphinic acid cannot react with amantadine due to its large steric hindrance. The purified monoalkylphosphinic acid was then reacted with olefin B (diisobutylene) to yield nonsymmetric dialkylphosphinic acid (NSDAPA). The unreacted monoalkylphosphinic acid can be easily removed by a simple base-acid post-treatment and other organic impurities can be separated out through the precipitation of the cobalt salt. The structure of the (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid was confirmed by 31P NMR, 1H NMR, ESI-MS, and FT-IR. The purity was determined by a potentiometric titration method, and the results indicate that the purity can exceed 96%.

A protocol for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants is presented, taking (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example.

We present the synthesis of (2,3-dimethylbutyl)(2,4,4&#39;-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high ...

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and cost savings through the &#34;scaling out&#34; strategy as opposed to the traditional &#34;scaling up&#34;. Herein, we report the reaction of diphenyldiazomethane with p-nitrobenzoic acid in both batch and flow modes. To effectively transfer the reaction from batch to flow mode, it is essential to first conduct the reaction in batch. As a consequence, the reaction of diphenyldiazomethane was first studied in batch as a function of temperature, reaction time, and concentration to obtain kinetic information and process parameters. The glass flow reactor set-up is described and combines two types of reaction modules with &#34;mixing&#34; and &#34;linear&#34; microstructures. Finally, the reaction of diphenyldiazomethane with p-nitrobenzoic acid was successfully conducted in the flow reactor, with up to 95% conversion of the diphenyldiazomethane in 11 min. This proof of concept reaction aims to provide insight for scientists to consider flow technology&#39;s competitiveness, sustainability, and versatility in their research.

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Flow chemistry carries environmental and economic advantages by leveraging superior mixing, heat transfer and cost benefits. Herein, we provide a blueprint to transfer chemical processes from batch to flow mode. The reaction of diphenyldiazomethane (DDM) with p-nitrobenzoic acid, conducted in batch and flow, was chosen for proof of concept.

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and ...

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of NixNb1-xO nanoparticles with different atomic compositions (x = 0.03, 0.08, 0.15, and 0.20) have been prepared by chemical precipitation. These NixNb1-xO catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The study revealed the sponge-like and fold-like appearance of Ni0.97Nb0.03O and Ni0.92Nb0.08O on the NiO surface, and the larger surface area of these NixNb1-xO catalysts, compared with the bulk NiO. Maximum surface area of 173 m2/g can be obtained for Ni0.92Nb0.08O catalysts. In addition, the catalytic hydroconversion of lignin-derived compounds using the synthesized Ni0.92Nb0.08O catalysts have been investigated.

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

A protocol for the synthesis of sponge-like and fold-like Ni1-xNbxO nanoparticles by chemical precipitation is presented.

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts

This paper presents a method to prepare charge-transfer chromophores using polyoxotungstate (PW12O403-), transition metal ions (Ce3+ or Co2+), and organic polymers, with the aim of photo-activating oxygen-evolving manganese oxide catalysts, which are important components in artificial photosynthesis. The cross-linking technique was applied to obtain a self-standing membrane with a high PW12O403- content. Incorporation and structure retention of PW12O403- within the polymer matrix were confirmed by FT-IR and micro-Raman spectroscopy, and optical characteristics were investigated by UV-Vis spectroscopy, which revealed successful construction of the metal-to-metal charge transfer (MMCT) unit. After deposition of MnOx oxygen evolving catalysts, photocurrent measurements under visible light irradiation verified the sequential charge transfer, Mn &#8594; MMCT unit &#8594; electrode, and&#160;the photocurrent intensity was consistent with the redox potential of the donor metal (Ce or Co). This method provides a new strategy for preparing integrated systems involving catalysts and photon-absorption parts for use with photo-functional materials.

Here, we present a protocol to prepare charge transfer chromophores based on a polyoxometalate/polymer composite membrane.

This paper presents a method to prepare charge-transfer chromophores using polyoxotungstate (PW12O403-), transition metal ions (Ce3+ or Co2+), and organic ...

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.

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

Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether

We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid nanosheets, a series of Pt/xHMNO6/CNTs with different solid acid compositions (x = 5, 20 wt%; M = Nb, Ta; N = Mo, W) have been prepared by carbon nanotube pretreatment, protonic exchange, solid acid exfoliation, aggregation and finally Pt particles impregnation. The Pt/xHMNO6/CNTs are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and NH3-temperature programmed desorption. The study revealed that HNbWO6 nanosheets were attached on CNTs, with some edges of the nanosheets being bent in shape. The acid strength of the supported Pt catalysts increases in the following order: Pt/CNTs &#60; Pt/5HNbWO6/CNTs &#60; Pt/20HNbMoO6/CNTs &#60; Pt/20HNbWO6/CNTs &#60; Pt/20HTaWO6/CNTs. In addition, the catalytic hydroconversion of lignin-derived model compound: diphenyl ether using the synthesized Pt/20HNbWO6 catalyst has been investigated.

A protocol for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs is presented.

We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid ...