Comparative evaluation of gas chromatographic techniques for determination of hydrogen used for isopropyl alcohol synthesis

Abstract

During the synthesis of isopropyl alcohol by the acetone hydrogenation reaction, it is necessary to control the content of impurities in the hydrogen used, since its purity determines the quality of the product, and impurities of CO and CO₂ are catalytic poisons for this reaction. At the «Omsky Kauchuk» plant, the purity of hydrogen is determined by gas chromatography using two different chromatographs — laboratory and flow. A comparison of the results of the parallel determination of hydrogen purity revealed a discrepancy of about 10 % wt., while the flow chromatograph did not detect impurities of CO and CO₂, the content of which, according to the laboratory chromatograph, was 0.10 and 0.016 % wt., respectively; the nitrogen content was significantly underestimated. Based on the conducted research, it was found that the sorbent of the nozzle column of the flow chromatograph is not suitable for the determination of CO₂ that distorts the results of hydrogen determination. In this regard, other options for nozzle columns with a CO₂-selective sorbent are proposed for use with a flow chromatograph, and it is also necessary to periodically warm up the column to remove volatile contaminants.