{"id":2538,"date":"2026-06-25T18:44:27","date_gmt":"2026-06-25T18:44:27","guid":{"rendered":"https:\/\/www.vogelbusch-biocommodities.com\/process-units\/dehydration\/molecular-sieve-process\/"},"modified":"2026-06-25T18:56:34","modified_gmt":"2026-06-25T18:56:34","slug":"molecular-sieve-process","status":"publish","type":"page","link":"https:\/\/www.vogelbusch-biocommodities.com\/en\/process-units\/dehydration\/molecular-sieve-process\/","title":{"rendered":"Molecular Sieve Process"},"content":{"rendered":"

Ethanol drying with molecular sieves<\/h2>\n

Water and ethanol form an azeotrope that limits how much water can be extracted by conventional distillation.<\/p>\n

The Vogelbusch molecular sieve system allows the dehydration of ethanol past 95 % purity. It removes water from the ethanol\/water vapor mixture that exits the rectification column to gain a dehydrated product. The dryness of this product can be tailored to meet specifications – anywhere from bioethanol with a water content of 0.5 % to super dry ethanol for pharmaceutical or industrial applications with a water content of 0.01 % or less.<\/p>\n

Design options<\/h3>\n

Depending on the condition of hydrous ethanol feedstock and the presence of an alcohol distillation plant, there are two different design options for the dehydration unit: integrated or stand-alone.<\/p>\n\n

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For key figures for dehydration plant construction<\/p>\n

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Integrated drying units for vaporous feed<\/strong><\/p>\n

are linked to a distillation and receive hydrous ethanol vapors directly from the rectification column. The regeneration, or purge, stream is returned to the distillation for recovery of ethanol.<\/p>\n

The greatest advantage of the integrated system is a considerable reduction in energy consumption when compared to uncoupled systems. The energy-efficient heat integration of dehydration with distillation \/ rectification \/ evaporation – a proprietary system introduced by Vogelbusch – also minimizes capital costs.<\/p>\n

Feed requires a minimum pressure of 0.5 barg.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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Stand-alone drying units for liquid feed<\/strong><\/p>\n

are used for hydrous ethanol liquid from storage. The hydrous ethanol is vaporized in a small recycle column. The regeneration, or purge, stream is returned to the recycle column for recovery of ethanol.<\/p>\n

The energy consumption of the ethanol drying unit is minimized by an optimal design of heat recovery under consideration of feedstock and utility conditions.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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Process principle<\/strong><\/p>\n

Molecular sieve dehydration employs an adsorption process using synthetic zeolite, a crystalline, highly porous material. The process is based on the principle that zeolite’s affinity for water changes at different pressures. The water loading of the zeolite depends on the partial pressure of the water in the feed which can be influenced by altering the pressure.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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PSA – Pressure swing adsorption process<\/strong><\/p>\n

The molecular sieve bed is fed with superheated vapor so that no condensation will occur. Water vapor is adsorbed into the pores of the zeolite, and ethanol vapor passes through the bed.<\/p>\n

Once the molecular sieve bed is saturated with water and a breakthrough is imminent, it has to be regenerated: the water is desorbed from the zeolite by reducing the pressure applied to it.<\/p>\n

Continuous production is realized by utilizing a pressure swing adsorption system with two molecular sieve beds. One bed is in dehydration service, while the other bed is regenerated under vacuum. During regeneration, bed pressure is lowered and the desorbed water is swept out of the bed with product vapors from the other bed in dehydration service. This regeneration, or purge, stream is then condensed and pumped to distillation for recovery of ethanol.<\/p>\n

The process is fully automated.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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Zeolite testing<\/strong><\/p>\n

For best quality selection we examine molecular sieve materials of various manufacturers. In a standardized quick test developed by Vogelbusch, the key performance parameters are analyzed and compared. This quick test is done on every batch of molecular sieve material before it is loaded into a commercial molecular sieve unit.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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Skid-mounted installation<\/strong><\/p>\n

For ease of installation, and reduced field erection time and costs, Vogelbusch can supply prefabricated molecular sieve units. They are compact to ship and easily reassembled on site.<\/p>\n

More about Skid-mounted solutions<\/a><\/strong><\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n \n

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Example<\/strong><\/p>\n

Double set of molecular sieve beds with a daily dehydration capacity of 1.3 million liters ethanol.<\/p>\n\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n\n

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FAQ<\/h2>\n \n

Frequently asked questions on the installation of a molecular sieve unit:<\/p>\n \n

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