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Molecular Sieve Desiccants in the Chemical Process Industry

Molecular Sieve Desiccants in the Chemical Process Industry

Molecular sieve desiccants are zeolite material with pores of uniform sizes. They efficiently adsorb gases and liquids based on their molecular size and polarity. Being a potential adsorbent for different liquids and gases, molecular sieve desiccants find their application in the steel production process, drying the inner space of the insulated glass window, filtration of oxygen in breathing apparatuses and air conditioning filter cores in our cars. It is used as a cost-effective and safe alternative in various applications in the chemical process industry. Based on the pore size, molecular sieve desiccants are mainly differentiated into four types: 3A, 4A, 5A, and 13X. The 3A molecular sieve desiccants find major application in petroleum and chemical industries for refining oil, polymerization, and chemical gas-liquid depth drying. The 3A and 4A molecular sieves can adsorb air contaminants, water or carbon dioxide powerfully. Due to the high performance and renewability of these desiccants, the lithium hydrogen canisters have been replaced by molecular sieve for carbon dioxide removal from the spacecraft cabin atmosphere.

As mentioned above molecular sieves are used in various sectors of industries and one of them is molecular sieve oxygen concentrators, which is used primarily in pharmaceutical production, water treatment, and glass manufacturing. Oxygen concentrators use these molecular sieves that work on the principle of rapid pressure swing adsorption of atmospheric nitrogen onto zeolite minerals, thus removing the nitrogen gas, leaving oxygen the major gas remaining.

Being highly porous with a pore diameter of 10A°, the 13x molecular sieve beads and pellets are used in adsorbing and drying water and moisture from different gases such as H2S, H2, CO2, O2, NH3, etc. It is used in general gas drying in air compressor units.  It also acts as a catalyst carrier. Due to their lower absolute retention, 13x types are used in the petroleum industry for the PONA analysis or the separation of naphthenes from paraffins, olefins, naphthenes and aromatics. It also is used in sweetening natural gases and liquid hydrocarbon streams by removing H2S and Mercaptans.