Gas chromatography, continuous reaction

Continuous reaction gas chromatography The dehydrogenation of cyclohexane over Pt/g-A1203 (with A.W. Wardwell and R.W. Carr, Jr.). American Chemical Society Symposium Series no. 196. Washington, D.C. American Chemical Society (1982). 

Continuous Reaction Gas Chromatography The Dehydrogenation of Cyclohexane over Pt/y-Al203... 

The cracking of diphenylmethane (DPM) was carried out in a continuous-flow tubular reactor. The liquid feed contained 29.5 wt.% of DPM (Fluka, >99%), 70% of n-dodecane (Aldrich, >99% solvent) and 0.5% of benzothiophene (Aldrich, 95% source of H2S, to keep the catalyst sulfided during the reaction). The temperature was 673 K and the total pressure 50 bar. The liquid feed flow rate was 16.5 ml.h and the H2 flow rate 24 l.h (STP). The catalytic bed consisted of 1.0 g of catalyst diluted with enough carborundum (Prolabo, 0.34 mm) to reach a final volume of 4 cm. The effluent of the reactor was condensed at high pressure. Liquid samples were taken at regular intervals and analyzed by gas chromatography, using an Intersmat IGC 120 FL, equipped with a flame ionization detector and a capillary column (Alltech CP-Sil-SCB). 

After the activation period, the reactor temperature was decreased to 453 K, synthesis gas (H2 CO = 2 1) was introduced to the reactor, and the pressure was increased to 2.03 MPa (20.7 atm). The reactor temperature was increased to 493 K at a rate of 1 K/min, and the space velocity was maintained at 5 SL/h/gcat. The reaction products were continuously removed from the vapor space of the reactor and passed through two traps, a warm trap maintained at 373 K and a cold trap held at 273 K. The uncondensed vapor stream was reduced to atmospheric pressure through a letdown valve. The gas flow was measured using a wet test meter and analyzed by an online GC. The accumulated reactor liquid products were removed every 24 h by passing through a 2 pm sintered metal filter located below the liquid level in the CSTR. The conversions of CO and H2 were obtained by gas chromatography (GC) analysis (micro-GC equipped with thermal conductivity detectors) of the reactor exit gas mixture. The reaction products were collected in three traps maintained at different temperatures a hot trap (200°C), a warm trap (100°C), and a cold trap (0°C). The products were separated into different fractions (rewax, wax, oil, and aqueous) for quantification. However, the oil and wax fractions were mixed prior to GC analysis. 

Solution of the educts and catalyst are pumped through the system, which is controlled by electronic balances. The actual reaction is performed in 87 ml continuous-flow reactor, from which samples are taken automatically and analyzed by gas chromatography (GC). The analytical data are processed online. 

A continuous-flow reactor with a fixed catalyst bed was employed at pressurized conditions. Gaseous dimethyl ether was supplied to the reactor at its vapor pressure with carbon monoxide while liquid reactants such as methyl acetate, methyl iodide, and water were fed with microfeeders. Methyl acetate used in this experiment was dehydrated by Molecular Sieve 5A before use. A part of the reaction mixture was sampled with a heated syringe and was analyzed by gas chromatography. 

To a 300 mL Hastelloy-B autoclave was added 31.0 mL (24.5 g, 765 mmol) of methanol, 90.0 mL (70.Og, 378 mmol) of tributyl amine, 33.0 mL (33.8 g, 251 mmol) of 1-chloropinacolone, 14.0 mg (0.019 mmol) of [(cyclohexyl)3P)]2PdCl2, and 28.0 mg (0.1 mmol) of tricyclohexylphosphine. The autoclave was sealed, flushed with carbon monoxide, and pressurized to 30 psi with CO. The autoclave was then heated to 120°C and the pressure was adjusted to 150 psi. The temperature and pressure were maintained using a continuous carbon monoxide feed for 3 h. The mixture was then cooled to yield a two phase reaction product. The entire product mixture (both layers) was diluted with 50.0 mL (39.55 g) of methanol to generate a homogeneous mixture and analyzed by gas chromatography. Variations in the procedure regarding temperature, pressure, catalyst levels (phosphine and Pd) are indicated in the tables and text. 

Small amounts (1.1 ml.) of 1-butene or butadiene were pulsed over ca. 1 gram of the oxide heated in a microreactor, the continuous gas current being He. The reaction products were separated by gas chromatography (8 meters 15% demethylsulfolane on Chromosorb 30/60). This was repeated for various temperatures of the microreactor. The oxides used (see Appendix) and their surface areas are given in Table I, which also summarizes the information derived from the runs. The following parameters were used ... 

The catalytic activity of SBA and AISBA samples toward cumene cracking were tested in a continuous flow fixed-bed microreactor system with helium (25 mL min 1) as carrier gas. The catalyst load for the tests was 100 mg and the catalyst was preheated at 573 K under helium flow for 3 h. For the reaction, a stream of cumene vapor in helium was generated using a saturator at room temperature. The reaction products were analyzed by gas chromatography. 

The effect of reaction conditions (temperature, pressure, H2 flow, C02 and/or propane flow, LHSV) and catalyst design on reaction rates and selectivites were determined. Comparative studies were performed either continuously with precious-metal fixed-bed catalysts in a trickle-bed reactor, or batchwise in stirred-tank reactors with supported nickel or precious metal on activated carbon catalysts. Reaction products were analyzed by capillary gas chromatography with regard to product composition, by titration to determine iodine and acid value, and by elemental analysis. 

A flame-dried flask containing nitroethane (0.4 mL) and catalyst (10.4 mg, 20 pmol, 0.1 equiv) was cooled to —20 °C, and then treated with the imine (50.0 mg, 200 pmol, 1.0 equiv). Stirring was continued at —20 °C and the reaction monitored by gas chromatography (GC). On complete consumption of the imine, the solution was concentrated in vacuo and purified by FC on silica gel... 

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