Insight into the Adsorption Process of Ethanol and Water on the Pore Structure and Surface Chemistry Properties Engineered Activated Carbon Fibers

Review of the Pressure Swing Adsorption Process for the Production of Biofuels and Medical Oxygen: Separation and Purification Technology

The production of biofuels has had a great impact on climate change and the reduction of the use of fossil fuels. There are different technologies used for the separation and production of biofuels, which allow having compounds such as ethanol, methane, oxygen, and hydrogen, one of these promising technologies is the Pressure Swing Adsorption process (PSA). The objectives of this article focus on the production and purification of compounds that achieve purities of 99.5% bioethanol, 94.85% biohydrogen, 95.00% medical oxygen, and 99.99% biomethane through the PSA process; also, a significant review is contemplated to identify the different natural and synthetic adsorbents that have greater adsorption capacity, the different configurations in which a PSA operates are studied and identified, and the different mathematical models that describe the dynamic behavior of all the variables are established that interact in this PSA process, parametric studies are carried out in order to identify the variables that have the greatest effect on the purity obtained. The results obtained in this review allow facilitating the calculation of parameters, the optimization of the process, the automatic control to manipulate certain variables and to achieve the rejection of disturbances to have a recovery and production of biofuels with a high degree of purity.

Study on the applicability of pressurized physically activated carbon as an adsorbent in adsorption heat pumps

Activated carbon is a suitable adsorbent for adsorption heat pumps (AHPs) with ethanol refrigerants. Although chemically activated carbon with highly developed pore structures exhibits good ethanol adsorption, the associated high production costs inhibit its practical application as an AHP adsorbent. Moreover, although physical activation can produce inexpensive activated carbon, the limited pore development limits the ethanol uptake. Recently, we developed a pressurized physical activation method that can produce activated carbon with a well-developed pore structure and characteristic pore size distribution. In this study, we investigated the applicability of the pressurized physically activated carbon as an adsorbent in activated carbon–ethanol AHP systems. Because of the large number of pressurization-induced pores of appropriate size, the pressurized physically activated carbon showed effective ethanol uptake comparable with that of chemically activated carbon on a weight basis. Furthermore, on a volume basis, the pressurized physically activated carbon, with a high bulk density, showed much higher effective ethanol uptake than chemically activated carbon. These results confirm the potential of the pressurized physically activated carbon as a relatively inexpensive high-performance adsorbent for AHP systems with ethanol refrigerants.

Thanks to the large number of pressurization-induced pores of appropriate size and the high bulk density, the pressurized physically activated carbon showed much higher effective ethanol uptake than chemically activated carbon.