Abstract: Commonly available carbon dioxide may contain unacceptable amounts of compounds containing greater than about ten carbon atoms, sulfur-containing materials, and nitrogen-containing materials which are particularly detrimental to semiconductor and silicon wafer processing-related uses of carbon dioxide. These impurities can be effectively removed by an apparatus containing a combination of metal oxide, silica gel, and activated carbon, thus permitting an on-site, on-demand, convenient, and economic method of purifying carbon dioxide ranging from laboratory scale operations to tank car scale operations.

Abstract: Commonly available carbon dioxide may contain unacceptable amounts of compounds containing greater than about ten carbon atoms, sulfur-containing materials, and nitrogen-containing materials which are particularly detrimental to semiconductor and silicon wafer processing-related uses of carbon dioxide. These impurities can be effectively removed by a combination of metal oxide, silica gel, and activated carbon, thus permitting an on-site, on-demand, convenient, and economic method of purifying carbon dioxide ranging from laboratory scale operations to tank car scale operations.

Abstract: A process for removing sulfur-containing compounds and halocarbons such as fluorocarbons and chlorocarbons from gases to provide gas streams which contain these compounds at unprecedentedly low levels using an adsorption train of four beds has been developed. The first bed serves to remove water, the second and third beds remove sulfur-containing compounds generally, and the fourth adsorbent bed removes sulfur-containing compounds and halocarbons such as chlorocarbons and fluorocarbons to very low levels.

Abstract: Industrial grade carbon dioxide may contain unacceptable amounts of sulfur-containing materials, oxygen, and organic materials particularly detrimental to food-related uses of CO.sub.2. These can be effectively removed by a bed of silver-exchanged faujasite and an MFI-type molecular sieve. This permits an on-site, on-demand method of purifying CO.sub.2 ranging from laboratory to tank car seals.

Abstract: The purge and trap procedure commonly used for analysis of volatile organic compounds in water or air can be significantly improved using traps employing molecular sieves as adsorbents. Silicalite and potassium-exchanged dealuminated zeolite Y form an effective mixture.