The separation of short-chained alkanes and alkenes is challenging because of their chemical similarity and thus being costly in energy. The implementation of a cryogenic adsorption process may overcome this problem, but systematic studies on light hydrocarbon adsorption at low temperatures are virtually lacking. Therefore, as a first step, in this paper, we present single-component adsorption isotherms of ethane, ethylene, propane, and propylene on activated carbon (AC) and zeolite 13X for temperatures of −80 to +20 °C and partial pressures of 5–1250 Pa. Based on these experimental data, the interactions of the adsorptives with the chemically different surfaces and their temperature dependence are discussed. Results show a strong increase in capacity with decreasing temperature for both AC and zeolite 13X. Cryogenic adsorption increases the overall (calculated) selectivity of alkane–alkene separation, especially for the zeolite 13X.

During the adsorptive separation of light hydrocarbons in the trace range, significant coadsorption of the carrier gas may occur due to low temperatures and much higher concentrations of the carrier gas compared to the adsorptive. This results in a reduction of the adsorbent's capacity, which leads to problems in industrial adsorber design and an incorrect interpretation of adsorption mechanisms. So far, there are only few studies on the carrier gas influence, and no data exist for low temperatures. In this work, we present experimental adsorption isotherms of methane and ethane from nitrogen and helium at temperatures between −80 and +20 °C on activated carbon and zeolite 13X. A comparison of the adsorption isotherms and the isosteric adsorption enthalpy reveals that coadsorption increases strongly with low temperatures, low partial pressures, and weak interactions between adsorptive and adsorbent. Finally, coadsorption is shown to be stronger on activated carbon than on zeolite 13X.

Auf der ACHEMA 2018 stellten sich 24 Firmen mit Bezug zum Themenfeld Adsorption vor. Das weit gefächerte Ausstellerfeld reichte von Adsorbentienherstellern über Messgeräteentwickler bis hin zu Anlagenbauern. Aufgrund der zeitlichen Nähe zur Fachmesse IFAT/Entsorga waren in diesem Jahr etwas weniger Aussteller vertreten als in den vorausgehenden Jahren. Der Bericht umreißt die wichtigsten Trends und Neuerungen aus der Adsorptionstechnik, die auf den Ständen präsentiert und in Gesprächen von den Ausstellern thematisiert wurden.

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