Biobutanol, or 1-butanol, is a very promising biofuel and platform chemical. As biofuel, it shows better properties than bio-ethanol, effectively breaking the blend wall. It also shows great promise for the use in chemical industry as C4 basic chemical and can be used as solvent, plasticiser or further processed in various chemicals and polymers1. 1-butanol can be produced from renewable resources via the acetone-butanol-ethanol (ABE) fermentation process. This fermentation process suffers from product inhibition, leading to final mixture concentrations of less than 2 wt%2. An efficient way to relieve product inhibition is via in situ removal of the produced 1-butanol via gas stripping3. However, this method is unselective towards 1-butanol: acetone and ethanol are also stripped into the gas phase. An energy-intensive distillation process4 is thus needed in the further downstream processing of 1-butanol, making the fermentation process uneconomical.

Adsorption has been identified as the most energy-efficient 1-butanol recovery method5. In this context, we studied the adsorption of 1-butanol from vapor phase mixtures, with the direct recovery and purification of 1-butanol from a stripping gas in mind. Three different zeolites were studied, with a first material being ITQ-29, an all-silica zeolite with LTA topology. Two other zeolites with a CHA topology were also studied: a polar SAPO-34 zeolite and an all-silica CHA. These materials were characterised via the measurement of vapor-phase isotherms and their dynamic selectivity was studied via the measurement of breakthrough profiles. ITQ-29 showed a high selectivity towards 1-butanol over the other mixture components, however, a small amount of ethanol and water co-adsorbed on this material. SAPO-34 and Si-CHA showed an opposite selectivity: ethanol and water were preferentially adsorbed over acetone and 1-butanol.

In a subsequent step, two fixed-bed adsorption columns containing a CHA-type zeolite and ITQ-29 were combined in one adsorption-desorption process for full 1-butanol purification. In a first step, an adsorption column containing ITQ-29 was completely saturated with a vapor phase ABE mixture. In a second step, this column was regenerated, by heating and flushing with an inert gas. This gas stream was then sent towards the column containing a CHA zeolite, removing ethanol and water co-adsorbed with 1-butanol on ITQ-29. Via this process, 99% of the adsorbed 1-butanol on ITQ-29 could be recovered at a purity of 99.5 mole-%.
Original languageEnglish
StatePublished - 10 Apr 2017
Event40th Annual Meeting of the British Zeolite Association - Preston, United Kingdom

Conference

Conference40th Annual Meeting of the British Zeolite Association
CountryUnited Kingdom
CityPreston
Period10/04/1712/04/17

ID: 30418087