炭化水素タイプ分析のためのスクラバーに関する二,三の知見
スポンサーリンク
概要
- 論文の詳細を見る
The subtractive technique has been utilized in gas chromatography in order to have simpler chromatograms and to make identification of peaks easier. In applying this subtractive technique, chemical absorbing agents (scrubbers) are often employed. Attempts have been made by combining such scrubbers with hydrogen flame ionization detector (FID) in evaluating the emission of hydrocarbons in automotive exhaust gases. As the scrubbers that can be applied for such a system, those prepared by coating HgSO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB>, PdSO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB>, Ag<SUB>2</SUB>SO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB> and Hg (ClO<SUB>4</SUB>)<SUB>2</SUB> onto firebrick or diatomaceous earth have been known so far.<BR>However, the effect of the operating conditions of a scrubber on the selectivity in absorbing hydrocarbons is not sufficiently understood.<BR>In this paper, it was noted that a scrubber would be affected by its water content and the temperature under which this scrubber was applied. For instance, the Hg(ClO<SUB>4</SUB>)<SUB>2</SUB> scrubber, that is generally used in its dry state, removes olefins, acetylenes and aromatics at the room temperature. When this scrubber is put to use at a temperature in excess of 80°C, it further removes isoparaffins and cycloparaffins as well. As oppose to this trend, it does not remove specific portion of olefins and aromatics when the scrubber is wet. On the other hand, the HgSO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB> scrubber (this is normally used in its wet state) absorbs olefins (2-butenes, however, are not absorbed completely) and acetylenes at the room temperature. When this scrubber is put to use under its dry state and at a temperature higher than the room temperature, it functions in similar fashion as a scrubber using nothing but sulfuric acid. Other scrubbers are also affected by water content and operating temperature.<BR>In addition, a scrubber was prepared on trial basis by coating HgI<SUB>2</SUB>-KOH on diatomaceous earth in order to fractionate acetylene from olefins. It has been found that this scrubber could remove acetylene alone on selective basis out of a mixture consisting of hydrocarbons.<BR>Based upon the characteristics of such scrubbers, systems have been assembled on trial basis by combining the scrubbers and FID in order to apply such systems on the type analysis of hydrocarbons contained in automotive exhaust gases. For such systems, scrubbers by coating HgSO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB>, Hg (ClO<SUB>4</SUB>)<SUB>2</SUB> and HgI<SUB>2</SUB>-KOH onto diatomaceous earth have been put to use. It is for this reason, it is possible to measure paraffins, olefins, acetylenes and aromatics through such a system. The analyses of hydrocarbons found in automotive exhaust gases were done by using such systems. The results thus obtained agreed well with those obtained by the gas chromatographic analyses.<BR>The results noted in this paper can very well be applied in carrying out the type analysis of hydrocarbons in atmosphere.