The work described in this paper was fully supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (UGC/FDS25/E09/17). We also gratefully acknowledge the National Natural Science Foundation of China (21373038 and 21403026) for providing analytical instruments for catalyst characterization and fixed bed reactor for catalyst performance evaluation. Dr. Hongxu Qi would like to thank for the Research Assistantship granted by the Research Grants Council of Hong Kong (UGC/FDS25/E09/17).&#160;

CAUTION: For the proper handling methods, properties and toxicities of the chemicals described in this paper, refer to the relevant material safety data sheets (MSDS). Some of the chemicals used are toxic and carcinogenic and special care must be taken. Nanomaterials may potentially pose safety hazards and health effects. Inhalation and skin contact should be avoided. Safety precautions must be exercised, such as performing the catalyst synthesis in the fume hood and catalyst performance evaluation with autoclave reactors. Personal protective equipment must be worn.
1. Pretreatment of CNTs13
<ol>
	<li>Immerse 1.0 g of CNTs into 50 mL of nitric acid in a 100 mL beaker.</li>
	<li>Sonicate the solution at 25 &#176;C for 1.5 h to remove surface impurities and to enhance the anchoring effect of the catalyst.</li>
	<li>Transfer the solution into a 100 mL round bottom flask.</li>
	<li>Reflux the solution in a mixture of nitric acid (65%) and sulfuric acid (98%) at 60 &#176;C for overnight. Set the volume ratio at 3:1. This will create surface defects on the CNTs.</li>
	<li>Filter the solution to obtain the multiwall carbon nanotube solid. Wash the solid with deionized water.</li>
	<li>Dry the solid at 80 &#176;C for 14 h.</li>
</ol>
2. Preparation of HNbWO6 solid acid nanosheets15 by protonic exchange followed by exfoliation
<ol>
	<li>Mix stoichiometric amounts of Li2CO3 (0.9236 g) and metal oxides Nb2O5 (3.3223 g) and WO3 (5.7963 g) at a molar ratio of 1:1:2.</li>
	<li>Calcine the solid mixture at 800 &#176;C for 24 h with one intermediate grinding.</li>
	<li>Place 10.0 g of LiNbWO6 powder in 200 mL of 2 M HNO3 aqueous solution at 50 &#176;C and stir the solution mixture for 5 days (120 h) with one replacement of the acid at 60 h.</li>
	<li>Exchange the acid liquid every day and repeat step 2.3.</li>
	<li>Filter the solid and wash the solid with deionized water 3x.</li>
	<li>Dry the solid at 80 &#176;C overnight.</li>
	<li>Add an amount of 25 wt.% TBAOH (tetra (n-butylammonium) hydroxide) solution to 150 mL of deionized water solution with 2.0 g of protonated compound obtained in step 2.6 until the pH reaches 9.5 &#8211; 10.0.</li>
	<li>Stir the above solution for 7 days.</li>
	<li>Centrifuge the above solution and collect the supernatant solution that contains the dispersed nanosheets.</li>
</ol>
3. Preparation of HNbMO6 solid acid nanosheets
NOTE: The procedure is similar to that of step 2 except for the first and third steps.
<ol>
	<li>Mix stoichiometric amounts of Li2CO3 and metal oxides Nb2O5 and MoO3 in a molar ratio of 1:1:2.</li>
	<li>Calcine the above solid mixtures at 800 &#176;C in air for 24 h with one intermediate grinding.</li>
	<li>Place 10.0 g of LiNbMoO6 powder in 200 mL of 2 M HNO3 aqueous solution at 50 &#176;C and stir the solution mixture for 5 days (120 h) with one replacement of the acid at 60 h.</li>
</ol>
4. Preparation of HTaWO6 solid acid nanosheets
NOTE: The procedure is similar to that of step 2 except for the first and third steps.
<ol>
	<li>Mix stoichiometric amounts of Li2CO3 and metal oxides Ta2O5 and WO3 in a molar ratio of 1:1:2.</li>
	<li>Calcine the above solid mixtures at 900 &#176;C in air for 24 h with one intermediate grinding.</li>
	<li>Place 10.0 g of LiTaWO6 powder in 200 mL of 2 M HNO3 aqueous solution at 50 &#176;C and stir the solution mixture for 5 days (120 h) with one replacement of the acid at 60 h.</li>
</ol>
5. Preparation of HNbWO6/MWCNTs by the nanosheet aggregation method
<ol>
	<li>Add 2.0 g of multiwall CNTs obtained in step 1 to a 100 mL solution of HNbWO6 nanosheets in a 250 mL round bottom flask.</li>
	<li>Add 100 mL of 1.0 M HNO3 aqueous solution into the round bottom flask dropwise. This will aggregate the nanosheets samples.</li>
	<li>Continue to stir the solution at 50 &#176;C for 6 h.</li>
	<li>Filter the solid and wash the solid with deionized water 3x.</li>
	<li>Dry the solid at 80 &#176;C overnight.</li>
	<li>Weigh the dried solid and record the % loading of the solid acid on the MWCNT.</li>
</ol>
6. Preparation of Pt/20HNbWO6/CNTs by the impregnation method
<ol>
	<li>Dissolve the H2PtCl6&#8729;H2O into water (1.0 g/100 mL).</li>
	<li>Impregnate the as-prepared nanosheets modified CNTs materials with 1.34 mL of the above Pt aqueous solution.</li>
	<li>Dry the nanosheets CNTs materials at 80 &#176;C, and calcinate the materials at 400 &#176;C for 3 h.</li>
	<li>Obtain the Nb(Ta)-based solid acid nanosheets modified Pt/CNTs catalysts.</li>
</ol>
7. Hydrodeoxygenation of lignin-derived aromatic ether
NOTE: The chosen lignin-derived aromatic ether is diphenyl ether in this experiment. The chosen lignin-derived aromatic ether is diphenyl ether in this experiment. The activity of Pt/20HTaWO6/CNTs (88.8% conversion, not shown in this paper) is lower than Pt/20HNbWO6/CNTs (99.6%), thus the yield of cyclohexane decreases. Hence, although, higher selectivity of cyclohexane was obtained over Pt/20HTaWO6/CNTs, lower conversion of diphenyl ether limits its utilization. Using appropriate protective equipment and fume hood to perform the reaction using carcinogenic reagents.
<ol>
	<li>Dilute 0.05 grams of catalyst in 5 milliliters of quartz sand. Load the solution in the middle of a fixed bed reactor between two pillows of quartz wool.</li>
	<li>Reduce the catalyst in H2 (40 mL/min) at 300 &#176;C for 2 h.</li>
	<li>Pump the diphenyl ether feedstocks (including 5.0 wt.% reactant in n-decane and 2.0 wt.% n-dodecane as an internal standard for gas chromatography analysis) into the fixed bed reactor at different flow rates (0.05-0.06 mL/min)</li>
	<li>Collect the products at different space times defined as the ratio between the mass of catalyst W (g) and the flow rate of the substrate F (g/min). 
	<img alt="Equation 1" src="/files/ftp_upload/59870/59870eq1.jpg" /></li>
	<li>Identify the liquid products by an GC (HP-5, 30 m x 0.32 mm x 0.25 &#956;m) with 5977A MSD and analyze off-line by gas chromatography (GC 450, FID, FFAP capillary column 30 m x 0.32 mm x 0.25 &#956;m).</li>
	<li>Determine the conversion of reactants (conv.%), selectivity towards product I (Si %), and yield of product i (Yi %) using the following equations: 
	<img alt="Equation 2" src="/files/ftp_upload/59870/59870eq2.jpg" /> (1) 
	<img alt="Equation 3" src="/files/ftp_upload/59870/59870eq3.jpg" /> (2) 
	<img alt="Equation 4" src="/files/ftp_upload/59870/59870eq4.jpg" /> (3)</li>
</ol>

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We have nothing to disclose.

Pretreatment of CNTs with nitric acid does increase the specific surface area (SBET) significantly. Raw CNTs have a specific surface area of 103 m2/g while after treatment, the surface area was increased to 134 m2/g. Therefore, such pretreatment to create defects on the CNT surface will have a positive effect on the specific surface area on the catalysts after solid acid modification and platinum particle impregnation. Since the surface area will decrease after incorporation of nanosheets...

Many industrial processes for the manufacture of chemicals involve the use of aqueous inorganic acid. One typical example is the conventional H2SO4 process for the hydration of cyclohexane to produce cyclohexanol. The process involves a biphasic system, with the cyclohexane being in the organic phase and the cyclohexanol product being in the acidic aqueous phase, thus making the separation process by simple distillation difficult. Apart from difficulty in separation and recovery, inorganic acid is also highly toxic and corrosive to equipment. Sometimes, the use of inorganic acid generates byproducts that will lower the product yield and must be avoided. For example, the dehydration of 2-cyclohexene-1-ol to produce 1,3-cyclohexadiene using H2SO4 will lead to polymerization byproducts1. Thus, many industrial processes shift towards using solid acid catalysts. Various water tolerant solid acids are used to solve the above problem and to maximize the product yields, such as the use of HZSM-5 and Amberlyst-15. The use of high-silica HZSM-5 zeolite has been shown to replace H2SO4 in the production of cyclohexanol from benzene2. Since the zeolite is present in the neutral aqueous phase, the product will go to the organic phase exclusively, thus simplifying the separation process. However, due to Lewis acid-base adduct formation of water molecules to the Lewis acid sites, zeolitic materials still demonstrated lower selectivity due to the presence of inactive sites3. Among all these solid acids, Nb2O5 is one of the best candidates that contain both Lewis and Br&#216;nsted acid sites. The acidity of Nb2O5&#8729;nH2O is equivalent to a 70% H2SO4 solution, due to the presence of the labile protons. The Br&#216;nsted acidity, which is comparable to protonic zeolite materials, are very high. This acidity will turn to Lewis acidity following water elimination. In the presence of water, Nb2O5 forms the tetrahedral NbO4-H2O adducts, which may decrease in Lewis acidity. However, the Lewis acid sites are still effective since the NbO4 tetrahedral still have effective positive charges4. Such phenomenon has been demonstrated successfully in the conversion of glucose into 5-(hydroxymethyl)furfural (HMF) and the allylation of benzaldehyde with tetraallyl tin in water5. Water-tolerant catalysts are thus crucial in biomass conversion in renewable energy applications, especially when the conversions are performed in environmental benign solvents such as water.
Among the many environmental benign solid acid catalysts, functionalized carbon nanomaterials using graphene, carbon nanotubes, carbon nanofibers, mesoporous carbon materials have been playing an important role in the valorization of biomass due to the tunable porosity, extremely high specific surface area, and excellent hydrophobicity6,7. The sulfonated derivatives are particularly stable and highly active protonic catalytic materials. They can either be prepared by incomplete carbonization of sulfonated aromatic compounds8 or by sulfonation of incompletely carbonized sugars9. They have proven to be very efficient catalysts (e.g., for the esterification of higher fatty acids) with activity comparable to the use of liquid H2SO4. Graphenes and CNTs are carbon materials with a large surface area, excellent mechanical properties, good acid resistance, uniform pore size distributions, as well as resistance to coke deposition. Sulfonated graphene has been found to efficiently catalyze the hydrolysis of ethyl acetate10 and bifunctional graphene catalysts has been found to facilitate the one-pot conversion of levullinic acid to &#947;-valerolactone11. Bifunctional metals supported on CNTs are also very efficient catalysts for application in biomass conversion12,13 such as the highly selective aerobic oxidation of HMF to 2,5-diformylfuran over the VO2-PANI/CNT catalyst14.
Taking advantage of the unique properties of Nb2O5 solid acid, functionalized CNTs and bifunctional metal supported on CNTs, we report the protocol for the synthesis of a series of Nb(Ta)-based solid acid nanosheet modified Pt/CNTs with a high surface area by a nanosheet aggregation method. Furthermore, we demonstrated that Pt/20HNbWO6/CNTs, as a result of the synergistic effect of well-dispersed Pt particles and strong acid sites derived from HNbWO6 nanosheets, exhibit the best activity and selectivity in converting lignin-derived model compounds into fuels by hydrodeoxygenation.

<table>
	<tbody>
		<tr>
			<td>Carbon nanotubes (multi-walled)</td>
			<td>Sigma Aldrich</td>
			<td>724769</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitric acid (65%)</td>
			<td>Sigma Aldrich</td>
			<td>V000191</td>
			<td></td>
		</tr>
		<tr>
			<td>sulphuric acid (98%)</td>
			<td>MERCK</td>
			<td>100748</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium carbonate (&#62;99%)</td>
			<td>Aladdin</td>
			<td>L196236</td>
			<td></td>
		</tr>
		<tr>
			<td>Niobium pentaoxide (99.95%)</td>
			<td>Aladdin</td>
			<td>N108413</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten trioxide (99.8%)</td>
			<td>Aladdin</td>
			<td>T103857</td>
			<td></td>
		</tr>
		<tr>
			<td>Molybdenum trioxide (99.5%)</td>
			<td>Aladdin</td>
			<td>M104355</td>
			<td></td>
		</tr>
		<tr>
			<td>Tantalum oxide (99.5%)</td>
			<td>Aladdin</td>
			<td>T104746</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroplatinic acid hexahydrate, &#8805;37.50% Pt basis</td>
			<td>Sigma Aldrich</td>
			<td>206083</td>
			<td></td>
		</tr>
		<tr>
			<td>tetra (n-butylammonium) hydroxide 30-hydrate</td>
			<td>Aladdin</td>
			<td>D117227</td>
			<td></td>
		</tr>
		<tr>
			<td>Diphenyl ether, 98%</td>
			<td>Aladdin</td>
			<td>D110644</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Bromoacetophenone,98%</td>
			<td>Aladdin</td>
			<td>B103328</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyl ether,99.5%</td>
			<td>Sinopharm</td>
			<td>10009318</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Decane,98%</td>
			<td>Aladdin</td>
			<td>D105231</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Dodecane,99%</td>
			<td>Aladdin</td>
			<td>D119697</td>
			<td></td>
		</tr>
		<tr>
			<td>Autoclave Reactor</td>
			<td></td>
			<td></td>
			<td>CJF-0.05&#8212;0.1L (Dalian Tongda Equipment Technology Development Co., Ltd)</td>
		</tr>
		<tr>
			<td>Tube furnace</td>
			<td></td>
			<td></td>
			<td>SK2-1-10/12 (Luoyang Huaxulier Electric Stove Co., Ltd)</td>
		</tr>
	</tbody>
</table>

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.

X-ray diffraction patterns (XRD) have been studied for the precursor LiNbWO6 and the corresponding proton-exchanged catalyst sample HNbWO6 to determine the phase (Figure 1 and Figure 2). NH3-temperature programmed desorption (NH3-TPD) was used to probe the surface acidity of the catalyst samples (Figure 3). Scanning electron microscopy (SEM) with X-ray microanalysis and...

Watch this Scientific Journal Video about Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether at JoVE.com

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

Afinación de la acidez de los catalizadores Pt/ CNTs para la hidrodesoxigenación del éter de difenilo

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 ...

tuning-acidity-pt-cnts-catalysts-for-hydrodeoxygenation-diphenyl

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Acids and Bases

SCIENTISTS IN ACTION

8.8K vistas.  Dalian University of Technology. Los nanomateriales de carbono funcionalizados que utilizan grafeno, nanotubos de carbono, nanofibras de carbono y los materiales de carbono mesoporoso juegan un papel importante en la valorización de la biomasa debido a la porosidad sintonizable, la superficie específica extremadamente alta y la excelente hidrofobicidad. Este protocolo demuestra un método general para ajustar la acidez de los nanotubos de carbono de platino modificados de nanohoja de ácido sólido para la valorización de...

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

Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

Formación de estructuras biomoleculares ordenada por el auto-ensamblaje de péptidos cortos

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

Investigación

Química

Tuning a Parallel Segmented Flow Column and Enabling Multiplexed Detection

Active flow technology (AFT) is new form of column technology that was designed to overcome flow heterogeneity to increase separation performance in terms of efficiency and sensitivity and to enable multiplexed detection. This form of AFT uses a parallel segmented flow (PSF) column. A PSF column outlet end-fitting consists of 2 or 4 ports, which can be multiplexed to connect up to 4 detectors. The PSF column not only allows a platform for multiplexed detection but also the combination of both destructive and non-destructive detectors, without additional dead volume tubing, simultaneously. The amount of flow through each port can also be adjusted through pressure management to suit the requirements of a specific detector(s). To achieve multiplexed detection using a PSF column there are a number of parameters which can be controlled to ensure optimal separation performance and quality of results; that is tube dimensions for each port, choice of port for each type of detector and flow adjustment. This protocol is intended to show how to use and tune a PSF column functioning in a multiplexed mode of detection.

Here, we present a protocol for the operation and tuning of parallel segmented flow chromatography columns to enable multiplexed detection.

Puesta a punto del paralelo Columna de flujo segmentado y habilitación de detección de multiplexado

Active flow technology (AFT) is new form of column technology that was designed to overcome flow heterogeneity to increase separation performance in terms ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

Síntesis de Proteínas bioconjugados<em&gt; vía</em&gt; Química cisteína-maleimida

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Síntesis Facile de micelas similares a gusanos de luz visible mediada por dispersión Polimerización con catalizador Photoredox

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

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.

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.

La desoxigenación programada la temperatura de ácido acético en carburo de molibdeno Catalizadores

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

NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential nutrients. The objective of this work is to demonstrate the qualitative and quantitative analysis of encapsulated fish oil supplements using high-resolution 1H and 13C NMR spectroscopy utilizing two different NMR instruments; a 500 MHz and an 850 MHz instrument. Both proton (1H) and carbon (13C) NMR spectra can be used for the quantitative determination of the major constituents of fish oil supplements. Quantification of the lipids in fish oil supplements is achieved through integration of the appropriate NMR signals in the relevant 1D spectra. Results obtained by 1H and 13C NMR are in good agreement with each other, despite the difference in resolution and sensitivity between the two nuclei and the two instruments. 1H NMR offers a more rapid analysis compared to 13C NMR, as the spectrum can be recorded in less than 1 min, in contrast to 13C NMR analysis, which lasts from 10 min to one hour. The 13C NMR spectrum, however, is much more informative. It can provide quantitative data for a greater number of individual fatty acids and can be used for determining the positional distribution of fatty acids on the glycerol backbone. Both nuclei can provide quantitative information in just one experiment without the need of purification or separation steps. The strength of the magnetic field mostly affects the 1H NMR spectra due to its lower resolution with respect to 13C NMR, however, even lower cost NMR instruments can be efficiently applied as a standard method by the food industry and quality control laboratories.

Here, high-resolution 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy was used as a rapid and reliable tool for quantitative and qualitative analysis of encapsulated fish oil supplements.

Espectroscopía de RMN como una herramienta robusta para la Evaluación Rápida del perfil lipídico de los suplementos de aceite de pescado

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential ...

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.

Síntesis y Prueba de Catalizadores de Nanopartículas de Solución Sólida Pt-Cu Soportadas para la Deshidrogenación de Propano

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

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.

Método de precipitación química para la síntesis de Nb2O5 modificado a granel catalizadores de níquel con alta superficie específica

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 ...

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 método de síntesis rápida de Au, Pd y Pt Aerogels vía reducción directa basada en la solución

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

Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular physico-chemical properties of ionic liquids (ILs) are exploited to control both nucleation and growth processes. The nanoparticles form colloidal sols of very high colloidal stability in the IL, which is particularly interesting in view of their use as quasi-homogeneous catalysts. Procedures for both nanoparticle extraction in conventional solvents and for nanoparticle precipitation are presented. The size, structure and composition of the synthesized nanocrystals are confirmed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX). By this, we show that the nanocrystals are random-type alloy and of small (2-3 nm) size. The catalytic activity and selectivity in the hydrogenation of &#945;,&#946;-unsaturated aldehydes is tested in a semi-continuous batch-type reactor. In this context, the bimetallic Pt/Sn-based nanoparticles reveal a high selectivity towards the unsaturated alcohol.

A protocol for the synthesis of bimetallic nanoparticles in ionic liquids and the procedure of their catalytic testing in the selective hydrogenation of unsaturated aldehydes are described.

Síntesis de nanopartículas bimetálicas Pt/Sn-basados en líquidos iónicos

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular ...