We are grateful to the Canadian Natural Sciences and Engineering Research Council (RGPIN-2018-06748), the Canadian Foundation for Innovation (229288), the Canadian Institute for Advanced Research (BSE-BERL-162173), and Canada Research Chairs for financial support. This research was undertaken thanks in part to funding from the Canada First Research Excellence Fund, Quantum Materials and Future Technologies Program. We thank Ben Herring at the UBC Shared Instrument Facility for assistance with the GC-MS instrument and method development. We thank Dr. Monika Stolar for contributions to the development and editing of this manuscript. Finally, we thank the entire Berlinguette Group at the University of British Columbia for their continued support and collaboration in studying the membrane reactor.

1. Pd rolling
<ol>
	<li>Clean the Pd wafer bar with a mixture of hexanes using a cotton cloth. 
	CAUTION: Hexane is flammable, a health hazard, an irritant, and environmentally damaging. Work under proper ventilation (i.e., a snorkel or a fume hood).</li>
	<li>Roll the Pd wafer using a manual roller until reaching a thickness of &#8804;150 &#181;m, as determined by a digital micrometer.</li>
	<li>Roll the Pd using an automatic roller to a thickness of 25 &#181;m, as determined by a digital microme...

<ol>
	<li>Rytter, E., Hillestad, M., Austb&#248;, B., Lamb, J. J., Sarker, S., Lamb, J. J., Pollet, B. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+six+-+Thermochemical+production+of+fuels.">Chapter six - Thermochemical production of fuels.</a> Hydrogen, Biomass and Bioenergy. , 89-117 (2020).</li><li>Arpe, H. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Industrial Organic Chemistry. , (2017).</li><li>Orella, M. J., Rom&#225;n-Leshkov, Y., Brushett, F. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emerging+opportunities+for+electrochemical+processing+to+enable+sustainable+chemical+manufacturing.">Emerging opportunities for electrochemical processing to enable sustainable chemical manufacturing.</a> Current Opinion in Chemical Engineering. 20, 159-167 (2018).</li><li>May, A. S., Biddinger, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+to+control+electrochemical+hydrogenation+and+hydrogenolysis+of+furfural+and+minimize+undesired+side+reactions.">Strategies to control electrochemical hydrogenation and hydrogenolysis of furfural and minimize undesired side reactions.</a> ACS Catalysis. 10 (5), 3212-3221 (2020).</li><li>Tang, B. Y., Bisbey, R. P., Lodaya, K. M., Toh, W. L., Surendranath, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reaction+environment+impacts+charge+transfer+but+not+chemical+reaction+steps+in+hydrogen+evolution+catalysis.">Reaction environment impacts charge transfer but not chemical reaction steps in hydrogen evolution catalysis.</a> ChemRxiv. , (2022).</li><li>Iwakura, C., Yoshida, Y., Inoue, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+hydrogenation+system+of+4-methylstyrene+using+a+palladinized+palladium+sheet+electrode.">A new hydrogenation system of 4-methylstyrene using a palladinized palladium sheet electrode.</a> Journal of Electroanalytical Chemistry. 431 (1), 43-45 (1997).</li><li>Inoue, H., Abe, T., Iwakura, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successive+hydrogenation+of+styrene+at+a+palladium+sheet+electrode+combined+with+electrochemical+supply+of+hydrogen.">Successive hydrogenation of styrene at a palladium sheet electrode combined with electrochemical supply of hydrogen.</a> Chemical Communications. , 55-56 (1996).</li><li>Conde, J. J., Maro&#241;o, M., S&#225;nchez-Herv&#225;s, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pd-based+membranes+for+hydrogen+separation:+Review+of+alloying+elements+and+their+influence+on+membrane+properties.">Pd-based membranes for hydrogen separation: Review of alloying elements and their influence on membrane properties.</a> Separation and Purification Reviews. 46 (2), 152-177 (2017).</li><li>Wicke, E., Brodowsky, H., Z&#252;chner, H., Alefeld, G., VÖlkl, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+in+palladium+and+palladium+alloys.">Hydrogen in palladium and palladium alloys.</a> Hydrogen in Metals II. Topics in Applied Physics., edited by Alefeld, G., V&#246;lkl, J. 29, (1978).</li><li>Sato, T., Sato, S., Itoh, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+a+hydrogen-permeable+palladium+membrane+electrode+to+produce+hydrogen+from+water+and+hydrogenate+toluene.">Using a hydrogen-permeable palladium membrane electrode to produce hydrogen from water and hydrogenate toluene.</a> International Journal Hydrogen Energy. 41 (12), 5419-5427 (2016).</li><li>Sherbo, R. S., Delima, R. S., Chiykowski, V. A., MacLeod, B. P., Berlinguette, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+electron+economy+by+pairing+electrolysis+with+hydrogenation.">Complete electron economy by pairing electrolysis with hydrogenation.</a> Nature Catalysis. 1, 501-507 (2018).</li><li>Sherbo, R. S., Kurimoto, A., Brown, C. M., Berlinguette, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+electrocatalytic+hydrogenation+with+a+palladium+membrane+reactor.">Efficient electrocatalytic hydrogenation with a palladium membrane reactor.</a> Journal of American Chemical Society. 141 (19), 7815-7821 (2019).</li><li>Kurimoto, A., Sherbo, R. S., Cao, Y., Loo, N. W. X., Berlinguette, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrolytic+deuteration+of+unsaturated+bonds+without+using+D2.">Electrolytic deuteration of unsaturated bonds without using D2.</a> Nature Catalysis. 3, 719-726 (2020).</li><li>Jansonius, R. 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=Hydrogenation+without+H2+using+a+palladium+membrane+flow+cell.">Hydrogenation without H2 using a palladium membrane flow cell.</a> Cell Reports Physical Science. 1 (7), 100105 (2020).</li><li>Huang, 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=Electrolysis+can+be+used+to+resolve+hydrogenation+pathways+at+palladium+surfaces+in+a+membrane+reactor.">Electrolysis can be used to resolve hydrogenation pathways at palladium surfaces in a membrane reactor.</a> Journal of American Chemical Society Au. 1 (3), 336-343 (2021).</li><li>Delima, R. S., 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+hydrogenation+of+furfural+using+a+membrane+reactor.">Selective hydrogenation of furfural using a membrane reactor.</a> Energy and Environmental Science. 15 (1), 215-224 (2021).</li><li>Sato, T., Takada, A., Itoh, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-temperature+hydrogenation+of+toluene+by+electrolysis+of+water+with+hydrogen+permeable+palladium+membrane+electrode.">Low-temperature hydrogenation of toluene by electrolysis of water with hydrogen permeable palladium membrane electrode.</a> Chemistry Letters. 46 (4), 477-480 (2017).</li><li>Maoka, T., Enyo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overpotential+decay+transients+and+the+reaction+mechanism+on+the+Pd-H2+electrode.">Overpotential decay transients and the reaction mechanism on the Pd-H2 electrode.</a> Surface Technology. 8 (5), 441-450 (1979).</li><li>Kurimoto, 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=Physical+separation+of+H2+activation+from+hydrogenation+chemistry+reveals+the+specific+role+of+secondary+metal+catalysts.">Physical separation of H2 activation from hydrogenation chemistry reveals the specific role of secondary metal catalysts.</a> Angewandte Chemie International Edition. 60 (21), 11937-11942 (2021).</li></ol>

The Pd membrane enables hydrogen permeation and chemical hydrogenation. The preparation of this membrane is, therefore, important to the efficacy of the membrane reactor. The Pd membrane size, crystallography, and surface are tuned to improve the experimental results. Although Pd metal can evolve hydrogen at any thickness, the Pd membranes are rolled to 25 &#181;m. This standardization of membrane thickness ensures that the time it takes for hydrogen to permeate through the membrane is constant for all the experiments. M...

Thermochemical hydrogenation reactions are used in ~20% of all chemical synthesis1. These reactions require large quantities of H2 gas, which are usually derived from fossil fuels, temperatures between 150 &#176;C and 600 &#176;C, and pressures up to 200 atm2. Electrochemical hydrogenation is an appealing way to bypass these requirements and to drive hydrogenation reactions using water and renewable electricity3. For conventional electrochemical hydrogenation, an unsaturated feedstock is dissolved in a protic electrolyte in an electrochemical cell. When a potential is applied to the cell, water oxidation occurs at the anode, while hydrogenation occurs&#160;at the cathode. In this reaction setup, both electrochemical water oxidation and chemical hydrogenation occur in the same reaction environment. The organic substrate is dissolved in a protic electrolyte to enable both electrochemical water splitting and hydrogenation of the feedstock. The proximity of these reactions can lead to byproduct formation and electrode fouling when the reactant is susceptible to nucleophilic attack or if the reactant concentration is too high (&#62;0.25 M)4.
These challenges prompted our group to explore alternative ways to electrochemically drive hydrogenation reactions5,6,7. This search resulted in the use of a Pd membrane, which is conventionally used in hydrogen gas separation8. We use it as an electrode for water electrolysis on the electrochemical reactor side. This novel application of a palladium membrane enables the physical separation of the site of electrochemical water oxidation from the site of chemical hydrogenation. The resulting reactor configuration has two compartments: 1) an electrochemical compartment for hydrogen production; and 2) a chemical compartment for hydrogenation (Figure 1). Protons are generated in the electrochemical compartment by applying a potential across the Pt anode and the Pd membrane, which also serves as the cathode. These protons then migrate to the Pd membrane, where they are reduced to surface-adsorbed hydrogen atoms. The electrochemical compartment can be subdivided to include an optional cation exchange membrane to facilitate this proton migration. The surface-adsorbed hydrogen atoms permeate through the interstitial octahedral sites of the Pd fcc lattice9 and emerge on the opposite face of the membrane in the hydrogenation compartment, where they react with the unsaturated bonds of a given feedstock to form hydrogenated products7,10,11,12,13,14,15,16. The Pd in the membrane reactor, therefore, acts as (i) a hydrogen-selective membrane, (ii) a cathode, and (iii) a catalyst for hydrogenation.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65098/65098fig1v2.jpg" /> 
Figure 1: Hydrogenation in a membrane reactor. Water oxidation at the anode produces protons, which are reduced on the palladium cathode. H permeates through the Pd membrane and reacts with propiophenone to form propylbenzene. Hydrogen evolution is a competing reaction that can occur on either side of the palladium membrane. For atmospheric mass-spectrometry, no chemical feedstock is used, necessitating H to leave the reactor in the form of H2 gas in either the electrochemical or hydrogenation compartments. <a href="https://www.jove.com/files/ftp_upload/65098/65098fig1largev2.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The membrane reactor is assembled by sandwiching a Pd membrane between the anode and cathode compartments of an electrochemical H-cell12. Chemical-resistant O-rings are used to secure the membrane into place and ensure a leak-free seal. The electrochemical compartment of the membrane reactor contains a hydrogen-rich aqueous solution. In this study, we use 1 M H2SO4 and an anode that consists of a Pt wire enveloped in a 5 cm2 piece of platinum mesh. The anode is submerged in the electrolyte solution through a hole in the top of the electrochemical compartment. The chemical hydrogenation compartment contains a solvent and hydrogenation feedstock7,10,11,12,16,17. The hole at the top of the H-cell compartment is used for sampling. The experiments shown here use 0.01 M propiophenone in ethanol as the hydrogenation feed. However, the starting material (and concentration) can be varied to fit the experimental needs. For instance, a starting material that contains a long hydrocarbon chain and an alkyne functional group may be dissolved in pentane to improve solubility11. The applied current for the reaction can be between 5 mA/cm2 and 300 mA/cm2. All reactions are carried out under ambient temperature and pressure.
Atmospheric mass spectrometry (atm-MS) is used to measure the percent of hydrogen in the electrochemical compartment that permeates to the hydrogenation compartment11,12.&#160;This measurement is important to understand&#160;the energy inputs required for the membrane reactor, because it reveals the maximum possible hydrogen utilization (i.e., how much of the hydrogen being produced can actually be used for hydrogenation reactions). Hydrogen permeation through the Pd membrane is calculated by measuring the amount of H2 that evolves from both the electrochemical and hydrogenation compartments11,12. A permeation value of 100% means that all the hydrogen produced in the electrochemical compartment is transported through the Pd membrane to the hydrogenation compartment and then subsequently combines to form hydrogen gas. A permeation value of &#60;100% means&#160;that hydrogen evolution occurs in the electrochemical compartment prior to permeating through the membrane. As H2 is produced from either the electrochemical or hydrogenation compartment, it enters the instrument and is ionized to H2+. The quadrupole selects fragments of m/z = +2, and the corresponding charge is measured by the detector. The plot obtained by this technique is the ionic charge over time. The ionic charge is measured for the hydrogenation compartment first, and when the signal stabilizes, the channels are changed to measure the electrochemical compartment. Hydrogen permeation is calculated by dividing the average ionic charge in the hydrogenation compartment by the total ionic charge measured in the reactor (Equation 1)11,12. To calculate hydrogen permeation, H2 from the hydrogenation and electrochemical compartments are measured separately using atm-MS.
<img alt="Equation 1" src="/files/ftp_upload/65098/65098eq1v2.jpg" style="margin: auto;" /> (Eq. 1)
Gas chromatography mass spectrometry (GC-MS) is used to monitor the progress of the hydrogenation reaction12,14,15,16. To collect data for the example, the hydrogenation compartment of the reactor is filled with 0.01 M propiophenone in ethanol. By applying a potential across the Pt anode and the Pd cathode, reactive hydrogen is supplied to the hydrogenation compartment. The reactive hydrogen atoms then hydrogenate the unsaturated feedstock, and the products are quantified using GC-MS, where the sample is fragmented and ionized. By analyzing the mass of these fragments, the composition of the hydrogenation solution can be determined, and reaction rates can be calculated12,14,15,16.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
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		<tr>
			<td>Ag/AgCl Reference Electrode</td>
			<td>BASi research products</td>
			<td>MW-2021</td>
			<td>Reference electrode</td>
		</tr>
		<tr>
			<td>Analytical Balance</td>
			<td>Cole-Parmer</td>
			<td>RK-11219-03</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Atmospheric Mass Spectrometer</td>
			<td>ESS CatalySys</td>
			<td>NA</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Bench Power Supply</td>
			<td>Newark</td>
			<td>1550</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Conductive Copper Foil Electrical Tape&#160;</td>
			<td>McMaster Carr</td>
			<td>76555A711</td>
			<td>Electrochemical cell assembly</td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>Sigma Aldrich</td>
			<td>270997</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Electric Rolling Press with Dual Micrometer</td>
			<td>MTI Corporation</td>
			<td>MR100A</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Electrochemical glass H-cell</td>
			<td>University of British Columbia glass blowing</td>
			<td>NA</td>
			<td>Electrochemical cell assembly</td>
		</tr>
		<tr>
			<td>ESS catalysis QUADSTAR</td>
			<td>ESS CatalySys</td>
			<td>NA</td>
			<td>Software</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma Aldrich</td>
			<td>493511</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Flat Rolling Mill</td>
			<td>Pepetolls</td>
			<td>18700A</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Gas Chromatography Mass Spectrometer</td>
			<td>Agilent</td>
			<td>NA</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>GC-MS vial</td>
			<td>Agilent</td>
			<td>5067-0205</td>
			<td>Vial for GC-MS</td>
		</tr>
		<tr>
			<td>Hexanes</td>
			<td>Sigma Aldrich</td>
			<td>1.0706</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Hydrochloric Acid</td>
			<td>Sigma Aldrich</td>
			<td>258148</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution (30% v/v)</td>
			<td>Sigma Aldrich</td>
			<td>H1009</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Isopropyl Alcohol</td>
			<td>Sigma Aldrich</td>
			<td>W292907</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Masshunter Aquisition Software</td>
			<td>Agilent</td>
			<td>G1617FA</td>
			<td>Software</td>
		</tr>
		<tr>
			<td>Micropipette (100 &#181;L - 1000 &#181;L)</td>
			<td>Gilson</td>
			<td>F123602</td>
			<td>instrument</td>
		</tr>
		<tr>
			<td>Micropipette (20 &#181;L - 200 &#181;L)&#160;</td>
			<td>Gilson</td>
			<td>F123601</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Mitutoyo Digital Micrometer</td>
			<td>Uline</td>
			<td>H-2780</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Muffle Furnace</td>
			<td>MTI Corporation</td>
			<td>KSL-1100X</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Nitric acid</td>
			<td>Sigma Aldrich</td>
			<td>438073</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Nitrogen gas</td>
			<td>Sigma Aldrich</td>
			<td>608661</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Palladium (II) Chloride</td>
			<td>Sigma Aldrich</td>
			<td>520659</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Pd wafer bar, 1 oz, 99.95%</td>
			<td>Silver Gold Bull.</td>
			<td>NA</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Platinum Auxiliary Electrode</td>
			<td>BASi research products</td>
			<td>MW-1032</td>
			<td>Anode</td>
		</tr>
		<tr>
			<td>Potentiostat</td>
			<td>Metrohm</td>
			<td>PGSTAT302N</td>
			<td>Instrument</td>
		</tr>
		<tr>
			<td>Propiophenone</td>
			<td>Sigma Aldrich</td>
			<td>P51605</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Proton Exchange Membrane, Nafion 212</td>
			<td>Fuel cell store&#160;</td>
			<td>NA</td>
			<td>Electrochemical cell assembly</td>
		</tr>
		<tr>
			<td>Sulfuric acid&#160;</td>
			<td>Sigma Aldrich</td>
			<td>258105</td>
			<td>Reagent</td>
		</tr>
	</tbody>
</table>

hydrogen production and utilization in a membrane reactor

Industrial hydrogenation consumes ~11 Mt of fossil-derived H2 gas yearly. Our group invented a membrane reactor to bypass the need to use H2 gas for hydrogenation chemistry. The membrane reactor sources hydrogen from water and drives reactions using renewable electricity. In this reactor, a thin piece of Pd separates an electrochemical hydrogen production compartment from a chemical hydrogenation compartment. The Pd in the membrane reactor acts as (i) a hydrogen-selective membrane, (ii) a cathode, and (iii) a catalyst for hydrogenation. Herein, we report the use of atmospheric mass spectrometry (atm-MS) and gas chromatography mass spectrometry (GC-MS) to demonstrate that an applied electrochemical bias across a Pd membrane enables efficient hydrogenation without direct H2 input in a membrane reactor. With atm-MS, we measured a hydrogen permeation of 73%, which enabled the hydrogenation of propiophenone to propylbenzene with 100% selectivity, as measured by GC-MS. In contrast to conventional electrochemical hydrogenation, which is limited to low concentrations of starting material dissolved in a protic electrolyte, the physical separation of hydrogen production from utilization in the membrane reactor enables hydrogenation in any solvent or at any concentration. The use of high concentrations and a wide range of solvents is particularly important for reactor scalability and future commercialization.

Atm-MS is used to measure the ionic current of the hydrogen that is produced in the membrane reactor. We can use these measurements to quantify how much hydrogen permeates through the Pd membrane during electrolysis. First, the hydrogen evolving from the hydrogenation compartment is measured (Figure 3, left of the dotted lines). When the signal reaches a steady state, the channel is switched to the electrochemical compartment. The H2 gas evolving from the electrochemical compartme...

Watch this Scientific Journal Video about Hydrogen Production and Utilization in a Membrane Reactor at JoVE.com

Hydrogen Production and Utilization in a Membrane Reactor

Membrane reactors enable hydrogenation in ambient conditions without direct H2 input. We can track the hydrogen production and utilization in these systems using atmospheric mass spectrometry (atm-MS) and gas chromatography mass spectrometry (GC-MS).

Industrial hydrogenation consumes ~11 Mt of fossil-derived H2 gas yearly. Our group invented a membrane reactor to bypass the need to use H2 gas for ...

Our protocol describes a method to isolate electrochemical hydrogen production from chemical feedstock hydrogenation in a single reactor. We can characterize the amount of hydrogen used in the desired hydrogenation reaction. Electrochemistry is separated from hydrogenation chemistry.It reduces the chance of side reactions and allows working with more solvents and concentrations than if restricted to the use of an electrolyte. To begin, clean the palladium wafer bar using the cotton cloth dipped in hexane and roll it with a manual roller until the digital meter reads approximately 150 micrometers. Then use an automatic roller to reduce the thickness to 25 micrometers and cut it into pieces of the desired size.For annealing, load the rolled palladium foils into a muffle furnace under a nitrogen atmosphere. Heat them at 850 to 900 degrees Celsius for 1.5 hours by gradually increasing the temperature from 25 to 900 degrees Celsius at the rate of 60 degrees Celsius per hour. Prepare a cleaning solution by mixing 10 milliliters of nitric acid, 20 milliliters of 30%hydrogen peroxide, and 10 milliliters of deionized water.Submerge the annealed palladium foils in the cleaning solution for 20 to 30 minutes until the vigorous bubbling subsides or the solution turns yellow. After washing the palladium foils twice with deionized water, rinse with isopropyl alcohol and air dry. Then assemble the reactor using prepared palladium foils.To prepare the electroplating solution, dissolve palladium chloride into one molar hydrochloric acid. Fill the electrochemical compartment of the reactor with 24 milliliters of the prepared solution leaving the hydrogenation compartment empty. Place a platinum mesh anode and silver chloride reference electrode in the electrochemical compartment.Connect the electrodes to a potentiostat and apply the potential of 0.2 volts to palladium foil versus silver chloride until a 15C charge passes. After disassembling the reactor, rinse the resulting palladium membrane twice with deionized water and once with isopropyl alcohol. Once dried with air or nitrogen, check for a visible deposition of black palladium on the membrane surface.To assemble the reactor, sandwich the prepared palladium membrane between two halves of an electrochemical H cell. Place a chemical resistant gasket between the left side of the cell and the palladium membrane. Once an additional gasket is placed on the right side of the cell, use a clip to seal the reactor configuration.For electrochemical hydrogenation, fill the electrochemical compartment with 24 milliliters of one molar sulfuric acid. Insert a platinum counter electrode into the electrochemical compartment and connect it to the positive terminal of a power supply. Using copper tape, attach the palladium membrane to the negative terminal.Then apply a galvanostatic current of 250 milliamperes and 3 to 5 voltage across the cell for 15 minutes. After sampling 30 microliters of the reaction solution, add 24 milliliters in the chemical compartment maintaining galvanostatic current. Collect a sample every 15 minutes with a micro pipette.Dissolve in one milliliter of dichloromethane in GC-MS vial and store it until the reaction is complete. To analyze the samples, load them into the auto sampler tray. Then click on the MassHunter icon to launch the GC-MS software.Select sequence and then edit sequence to open the sequence editing window. Fill the sample name, vial position, method path, method file, data path, and data file into the chart. Set the sample type to sample and the dilution to 1.Click on the method followed by edit entire method to adjust the method. Check both method information and instrument acquisition and press OK.Also, verify data acquisition and data analysis are checked. Leave every other field blank and click OK.Set the sample inlet to GC and the injection source to GC ALS.Ensure the use MS box is checked, the inlet location is set to front, the MS is connected to front and then click OK.Under the inlet tab, set the heater temperature to 250 degrees Celsius, pressure to 7.2 pounds per square inch, and helium flow to 23.1 milliliters per minute. Under the oven tab, set the initial temperature to 50 degrees Celsius with a one minute hold. Set the ramp rate to 25 degrees Celsius per minute.The temperature to 200 degrees Celsius with a zero minute hold and press OK.Check that all display signals are not selected and click OK.Set the solvent delay to 2.50 minutes and select OK.Ensure the monitor includes GC oven temperature, GC inlet F temperature, GC inlet F pressure, GC column 2 flow calc, MS EM volts, MS MS source, MS MS quad, and click OK.Enter the desired method name to save the method. Click on the sequence followed by run sequence, and then select run sequence to start the sample analysis. Once the sequence is completed, open the MassHunter software and select the file name to view the data.To identify the product peaks, click spectrum, then library search report, and OK to compare the acquired mass spectra with the NIST database. Calculate the relative composition of starting materials and products using the equation. The atmospheric mass spectrometry measured the hydrogen produced in the hydrogenation compartment and an electrochemical compartment in the membrane reactor.The palladium membrane permeated 73%hydrogen with an average ionic current of 27 picoamperes in the hydrogenation compartment and 10 in the electrochemical compartment. In contrast, another membrane showed less than 1%permeation to hydrogen. GC-MS of hydrogenation under an electrochemical bias showed a sharp peak of the starting material propiophenone as the reaction progressed forming peaks represented propylbenzene and 1-Phenyl-1-propanol, while the propiophenone peak diminished.In contrast, propiophenone was not converted to the product when the palladium membrane was not electrochemically biased. However, the chromatogram displayed an unexpected peak attributed to an impurity. Under an electrochemically biased palladium membrane, the kinetic profile of the hydrogenation reaction demonstrated the composition change in starting material and products.In contrast, when the palladium membrane was not electrochemically biased, starting material composition was not changed as the product was not formed. It's important to assemble the reactor to prevent leakage between compartments. Sample the reaction with a precise instrument like a micro pipette to ensure quality data from the GC-MS.Additional characterization methods like H NMR can be performed to confirm the chemical structure of the reaction products.

hydrogen-production-and-utilization-in-a-membrane-reactor

Research

JoVE Journal

Chemistry

2.0K ビュー.  The University of British Columbia. 当社のプロトコルは、単一の反応器で電気化学的水素製造を化学原料水素化から分離する方法を説明しています。所望の水素化反応で使用される水素の量を特徴付けることができます。電気化学は水素化化学から分離されています。副反応の可能性を減らし、電解質の使用に制限されている場合よりも多くの溶媒と濃度での作業を可能にします。まず、ヘキサンに?...