Name: high-pressure sapphire cell for phase equilibria measurements of co2/organic/water systems
Uploaded: 2014-01-24T15:30:00
Description: Watch this Scientific Journal Video about High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems at JoVE.com

1. Assembly of the Sapphire Cell
<ol>
	<li>Place a 116 size backing ring and 210 size O-ring onto the piston. Verify that O-ring material is compatible with chemicals used during the experiment prior to assembly.
	<ol>
		<li>Some backing rings have a flat and a curved edge. If this is the case, place the flat edge down and the curved edge against the O-ring.</li>
	</ol>
	</li>
	<li>Thread rod into the bottom of the piston using a rod with a threaded tip (Figure 3).</li>
	<li>W...

<ol>
	<li>Hallett, J. P., Pollet, P., Eckert, C. A., Liotta, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recycling+homogeneous+catalysts+for+sustainable+technology.">Recycling homogeneous catalysts for sustainable technology.</a> Catal. Org. React. 115, 395-404 (2007).</li><li>Hallett, J. 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=Hydroformylation+catalyst+recycle+with+gas-expanded+liquids.">Hydroformylation catalyst recycle with gas-expanded liquids.</a> Ind. Eng. Chem. Res. 47, 2585-2589 (2008).</li><li>Pollet, P., Hart, R. J., Eckert, C. A., Liotta, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organic+Aqueous+Tunable+Solvents+(OATS):+A+Vehicle+for+Coupling+Reactions+and+Separations.">Organic Aqueous Tunable Solvents (OATS): A Vehicle for Coupling Reactions and Separations.</a> Accounts Chem. Res. 43, 1237-1245 (2010).</li><li>Fadhel, A. Z., 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=Exploiting+Phase+Behavior+for+Coupling+Homogeneous+Reactions+with+Heterogeneous+Separations+in+Sustainable+Production+of+Pharmaceuticals.">Exploiting Phase Behavior for Coupling Homogeneous Reactions with Heterogeneous Separations in Sustainable Production of Pharmaceuticals.</a> J. Chem. Eng. Data. 56, 1311-1315 (2011).</li><li>Briones, J. A., Mullins, J. C., Thies, M. C., Kim, B. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ternary+Phase-Equilibria+for+Acetic+Acid-Water+Mixtures+with+Supercritical+Carbon+Dioxide.">Ternary Phase-Equilibria for Acetic Acid-Water Mixtures with Supercritical Carbon Dioxide.</a> Fluid Phase Equilib. 36, 235-246 (1987).</li><li>Wendland, M., Hasse, H., Maurer, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiphase+High-Pressure+Equilibria+of+Carbon-Dioxide-Water-Isopropanol.">Multiphase High-Pressure Equilibria of Carbon-Dioxide-Water-Isopropanol.</a> J. Supercrit. Fluid. 6, 211-222 (1993).</li><li>Traub, P., Stephan, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Pressure+Phase-Equilibria+of+the+System+CO2+Water+Acetone+Measured+with+a+New+Apparatus.">High-Pressure Phase-Equilibria of the System CO2 Water Acetone Measured with a New Apparatus.</a> Chem. Eng. Sci. 45, 751-758 (1990).</li><li>Peng, D. -. Y., Robinson, D. B. <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+Two-Constant+Equation+of+State.">A New Two-Constant Equation of State.</a> Ind. Eng. Chem. Fund. 15, 59-64 (1976).</li><li>Stryjek, R., Vera, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PRSV+-+An+Improved+Peng-Robinson+Equation+of+State+with+New+Mixing+Rules+for+Strongly+Nonideal+Mixtures.">PRSV - An Improved Peng-Robinson Equation of State with New Mixing Rules for Strongly Nonideal Mixtures.</a> Can. J. Chem. Eng. 64, 334-340 (1986).</li><li>Michelsen, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Modified+Huron-Vidal+Mixing+Rule+for+Cubic+Equations+of+State.">A Modified Huron-Vidal Mixing Rule for Cubic Equations of State.</a> Fluid Phase Equilib. 60, 213-219 (1990).</li><li>Lazzaroni, M. J., 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=High-pressure+phase+equilibria+of+some+carbon+dioxide-organic-water+systems.">High-pressure phase equilibria of some carbon dioxide-organic-water systems.</a> Fluid Phase Equilib. 224, 143-154 (2004).</li><li>Lazzaroni, M. J., Bush, D., Brown, J. S., Eckert, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-pressure+vapor-liquid+equilbria+of+some+carbon+dioxide+plus+organic+binary+systems.">High-pressure vapor-liquid equilbria of some carbon dioxide plus organic binary systems.</a> J. Chem. Eng. Data. 50, 60-65 (2005).</li><li>Lazzaroni, M. J., Bush, D., Eckert, C. A., Glaser, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-pressure+vapor-liquid+equilibria+of+argon+plus+carbon+dioxide+2-propanol.">High-pressure vapor-liquid equilibria of argon plus carbon dioxide+2-propanol.</a> J. Supercrit. Fluid. 37, 135-141 (2006).</li><li>Laugier, S., Richon, D., Renon, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+Determination+of+Vapor-Liquid+Equilibiria+and+Volumetric+Properties+of+Ternary+Systems+with+a+New+Experimental+Apparatus.">Simultaneous Determination of Vapor-Liquid Equilibiria and Volumetric Properties of Ternary Systems with a New Experimental Apparatus.</a> Fluid Phase Equilib. 54, 19-34 (1990).</li><li>Fontalba, F., Richon, D., Renon, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+determination+of+vapor--liquid+equilibria+and+saturated+densities+up+to+45+MPa+and+433.">Simultaneous determination of vapor--liquid equilibria and saturated densities up to 45 MPa and 433.</a> 55, 944-951 (1984).</li><li>Lazzaroni, M. 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> Georgia Institute of Technology. , (2004).</li><li>Diandreth, J. R., Ritter, J. M., Paulaitis, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental-Technique+for+Determining+Mixture+Compositions+and+Molar+Volumes+of+3+or+More+Equilibrium+Phases+at+Elevated+Pressures.">Experimental-Technique for Determining Mixture Compositions and Molar Volumes of 3 or More Equilibrium Phases at Elevated Pressures.</a> Ind. Eng. Chem. Res. 26, 337-343 (1987).</li></ol>

The sapphire cell apparatus is a unique tool for measuring phase behavior without sampling, and thus equilibrium is not disturbed. To ensure accurate repeatable data, there are critical steps in the protocol (Protocol 4 entitled &#8220;Operation of the Sapphire Cell Apparatus&#8221;) that must be followed. For any system in which phase composition is measured, it is critical to reach equilibrium prior to measurement. The sapphire cell is placed on a rotating shaft that facilitates mixing to more rapidly achieve equilibri...

When reactions are being conducted with a hydrophilic catalyst and a hydrophobic substrate to form a hydrophobic product, it is quite common to employ mixed solvents in order to provide a homogeneous reaction system. For example, THF-water and acetonitrile-water are commonly mixed solvent vehicles for these homogenous reaction processes. Ideally, it would be advantageous to develop a process in which the reaction is performed under homogeneous conditions followed by an induced phase split to separate the aqueous and organic solvent components. The hydrophilic catalyst would then be located in the aqueous phase and the hydrophobic product in the organic phase. The overall process would enable a facile separation/isolation of product and a means to recycle the catalyst. Organic Aqueous Tunable Solvents (OATS) provide a vehicle to accomplish this strategy. The first step in developing OATS was to understand the phase behavior of the organic-aqueous solution as a function of organic/water proportion, CO2 pressure and temperature. The efficiency of the phase separation upon addition of CO2&#160;(i.e.&#160;the cross-solubility in each phase) is important to quantify. In fact from a process standpoint, cross-solubility can translate directly to product and catalyst losses in the undesired, respective phases. Therefore, knowing phase composition as a function of pressure is key information for &#8220;real-world&#8221; applications. Sampling methods are available;5-7&#160;however, direct sampling from high pressure systems may alter the equilibrium of the system and result in phase separation or flashing as a result of abrupt changes in pressure or temperature in the sample line. Therefore, a method that does not disturb the system and enables fast acquisition and reproducible data was preferable. The high pressure sapphire cell apparatus is indeed a versatile tool to measure phase behavior without sampling. Using a cathetometer, very precise volume measurements can be recorded. These experimental volume measurements are then used with the Peng-Robinson cubic equation of state (modifications of Stryjek and Vera) and modified Huron-Vidal mixing rules to effectively calculate volume expansion and phase compositions as a function of temperature and pressure8-10. This technique was specifically designed to measure phase equilibria of vapor-liquid-liquid systems. It should be highlighted that the sapphire cell is not suited to study systems that involve solids. The data acquired with the high-pressure sapphire cell guided the choice of experimental conditions for OATS mediated reactions, separations and catalyst recycling. Furthermore, the sapphire cell was also used to (1) measure solvent expansion (or swelling) as a function of CO2 pressure with organic solvents and ionic liquids, (2) determine catalyst partitioning in multiphase systems as a function of pressure, solvent system and temperature and (3) understand phase behavior in complex reaction systems conducted under pressure. Herein, we report (1) the description of high- pressure sapphire cell apparatus, (2) the possible limitations and safety precautions, (3) its operating protocol, and (4) specific proof of principle results.
The high-pressure sapphire cell discussed above was custom made (Figure 1). The equilibrium cell consists of a hollow sapphire cylinder (50.8 mm O.D. x 25.4&#177;0.0001 mm I.D. x 203.2 mm L). The cell is divided into two chambers separated by a piston. The bottom cell contains water used as a pressurizing fluid (dyed blue for demonstrative purposes) and the top cell contains the equilibrium components (Figure 2). The air bath was custom-constructed of Plexiglas to fit specific setting and hood-size. The cell is placed inside a temperature controlled airbath, which is maintained with a digital temperature controller. The temperature of the airbath is monitored with thermocouples (Type K) and digital readouts. There is an additional thermocouple (Type K) inside the sapphire cell that is also monitored with a digital readout. The pressures were measured with a pressure transducer and digital readout. Two high pressure, 500 ml, syringe pumps capable of maintaining pressure up to 10 MPa were required for operation. The first high pressure syringe pump contains water that is used to pressurize the system. The second high pressure pump was used to introduce CO2&#160;(or other gas) to the system. The gas inlet is at the top of the sapphire cell. The pressure is controlled with the high pressure syringe pump to achieve equilibrium pressure on both sides of the piston. The cell is mounted on a rotating shaft, and mixing is achieved by manually rotating the entire cell.
Liquid and vapor volumes are calculated by measuring the height of the meniscus with a micrometer cathetometer. For displacements less than 50 mm, the accuracy is 0.01 mm; for larger displacements, the accuracy is 0.1 mm.

<table border="0" cellpadding="0" cellspacing="0" width="623">
	<colgroup>
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:245px;">Hollow sapphire cylinder</td>
			<td style="width:379px;">50.8 mm O.D. &#215; 25.4&#177;0.0001 mm I.D. &#215; 203.2 mm L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressurizing fluid</td>
			<td>Water</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe pumps</td>
			<td>Teledyne Isco Model 500D</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital temperature controller</td>
			<td>Omega CN76000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital readouts</td>
			<td>HH-22 Omega</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermocouples</td>
			<td>Omega Type K</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressure transducer &#38; readout</td>
			<td>Druck, DPI 260, PDCR 910</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CO2</td>
			<td>SCF grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cathetometer</td>
			<td>Gaertner Scientific corporation or any scientific lab suppliers.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Relief valve</td>
			<td>Spring loaded releive valve (swagelok)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">mounting bracket</td>
			<td>UNISTRUT&#160; bracket</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hollow spacers</td>
			<td>3/4 inch</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4 stainless steel bolts, 4 nuts, 2 washers</td>
			<td>3/4 inch</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3 O-rings&#160;</td>
			<td>Kalrez, 210 size&#160;&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3 backing rings&#160;</td>
			<td>116 size for piston; 2 8210 size for end caps</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 multi-port fitting</td>
			<td>HiP</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">High pressure tubing</td>
			<td>Stainless steel, 1/16 in.</td>
		</tr>
	</tbody>
</table>

high-pressure sapphire cell for phase equilibria measurements of co2/organic/water systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

The schematic of the high-pressure sapphire cell is shown in Figure 2, along with a picture of the cell. The sample is in the top cell and in the bottom cell is water with blue dye for demonstration purposes. The liquid components are fed via a syringe and valve, while the CO2 (gas component) is pumped through a high pressure syringe pump. The pressure can be controlled through the piston (the water is also fed via high pressure syringe pump in our setup). The liquid and gas phases can be clea...

Watch this Scientific Journal Video about High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems at JoVE.com

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

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