Solvent Drying
and Treating
Various hydrocarbon solvents from propane to alcohols sometimes contain impurities such as water, sulfur and oxygenates that must be removed to meet product and customer specifications. Zeochem molecular sieves are utilized for removal of these impurities to meet those requirements. The most common impurities are water and sulfur compounds such as hydrogen sulfide and mercaptans. Alcohol itself can be a solvent, but it can also be an impurity in various hydrocarbon solvents that must be removed in some cases.
Zeochem’s Z3-06 molecular sieve is commonly used for dehydration of solvent streams when only water removal and no additional component removal is needed. It minimizes co-adsorption of other stream components such as hydrocarbons, carbon dioxide and sulfur contaminants. For systems using a slipstream of the dry product for regeneration, the product and regeneration streams have a more consistent and predictable composition, minimizing spiking of contaminants in these streams, which could potentially cause off-specification product or the inability to dispose of a spent regeneration stream. Zeochem’s Z3-06 is normally regenerated at a temperature of 450°F (232°C) with a typical range of 400–500°F (204–260°C).
Zeochem’s Z3-03 molecular sieve is commonly used for the dehydration of alcohol streams to minimize co-adsorption of alcohol. It is normally regenerated at a temperature of 450°F (232°C) with a typical range of 400–500°F (204–260°C).
Zeochem’s Z4-04 molecular sieve is a standard grade of the 4A type zeolite that is used for dehydration of solvent streams. It can also be used to effectively remove methanol. While it can also remove some H2S and CO2, for targeted removal of these contaminants, one of the products listed below would be more suitable and therefore recommended. Also, if H2S and CO2 are present in the stream, the formation of COS can occur. To avoid COS formation, we offer alternative products that will minimize the occurrence. Z4-04 is normally regenerated at a temperature of 550°F (288°C) with a typical range of 500–600°F (260–315°C).
Our Z5-01 and other 5A molecular sieves are recommended for solvent treating when removal of small sulfur compounds such as H2S, methyl mercaptan or ethyl mercaptan is required. These products have excellent physical properties and a controlled pore structure, which provide optimum physical strength coupled with particularly high hydrothermal stability when used for sulfur removal in regenerative applications. These products also have excellent sulfur adsorption kinetics. The line of 5A molecular sieves contains a special grade recommended when hydrogen sulfide and carbon dioxide are present to minimize the formation of carbonyl sulfide (COS). 5A products normally regenerate at a temperature of 550°F (288°C) with a typical range of 500–600°F (260–315°C).
Our 13X molecular sieves are recommended when removal of larger sulfur species (mercaptans, sulfides) is required. It also removes water, alcohols and CO2, in addition to the smaller hydrogen sulfide, methyl mercaptan and ethyl mercaptan sulfur species. These products have an open pore structure, giving them excellent equilibrium and dynamic performance which is ideally suited for removal of sulfur compounds in regenerative and nonregenerative applications. For regenerable applications, these molecular sieves normally regenerate at a temperature of 550°F (288°C) with a typical range of 500–600°F (260–315°C).
