1986 Volume 29 Issue 1 Pages 80-83
An automatic gas chromatographic system was developed for rapid on-line analysis of low molecular weight oxygenated compounds and C1-C5 hydrocarbons produced in the gas phase hydrogenation of CO. The system was suitable for the analysis of about 30 components of product gases (CH3COOH, C2H5OH, CH3CHO, CH3COOCH3, CH3COOC2H5, n-C3H7OH, iso-C3H7OH, n-C4H9OH, iso-C4H9OH, C2H5CHO, C2H5COOH, CH3OH, CH3OCH3, HCOOCH3, HCOOC2H5, C1-C5 hydrocarbons, CO, CO2, H2, Ar, N2). All the compounds could be determined within 25min. Additional few minutes were required for data processing and print-out. Thus, a complete monitoring of the reaction could be carried out in every 30 minutes (Figs. 2, 3).
This analytical system consisted mainly of three linked isothermal gas chromatographs equipped with four series of analytical columns, sampling valves, a switching valve, back flushing devices, and five detectors (Fig. 1). The gas eluted from the reactor was led into the sampling valves through a heat-traced line and injected into the four series of analytical columns which were: Series 1: PEG-6000+Chromosorb 101 for acetic acid, propionic acid, n-butanol, iso-butanol, n-propanol, methyl formate, methyl acetate, ethyl acetate, hexanes (Fig. 2-a, b). Series 2: Chromosorb 101 (equipped with a back-flush device)+PEG-1500 for C4-hydrocarbons, C5-hydrocarbons, acetaldehyde, methyl formate, methanol, propanal, ethanol, isopropanol, (Fig. 2-c). Series 3: PEG-1500 (equipped with a back-flush device)+Porapak QS for methane, ethane, ethene, propane, propene, butane, butenes, dimethyl ether (Fig. 2-d). Series 4: Porapak QS (equipped with a back-flush device)+Molecular sieve 5A and Porapak QS in parallel for Ar, N2, CO2, CO, methane, ethane, ethene, H2O (Fig. 2-e).
System control, peak identification, integration, data processing, and print-out were carried out by using three linked integrators (Shimazu C-R2AX) with five data acquisition ports. An example of print-out is shown in Fig. 4.
The system described could be used successfully about 4, 000 times (for 2 years) to analyze the products formed in high pressure hydrogenation of CO.
