Production of Adsorption-Active Carbon Monoliths by 3D Printing and Study of Their Primary Characteristics

Traditionally, activated carbons are used as loose granular beds, which have several drawbacks, the most significant being granule attrition and high hydraulic resistance. An alternative is the use of adsorption-active materials in the form of monolithic structures. The classical shaping method for such materials is extrusion, which can produce both granular and monolithic forms, but the process is complex and limited in its ability to generate diverse geometries. In this work, a new method is proposed for producing carbon monoliths from thermosetting resins using 3D printing. The method involves 3D printing a mold of a specified geometry from a thermoplastic polymer whose melting temperature is lower than the polycondensation temperature of the thermosetting resin, filling the mold with the thermosetting resin, carrying out polycondensation inside the mold, and subsequently performing carbonization and steam–gas activation. Using this approach, monoliths with heights ranging from 2.6 to 8.6 cm and straight circular channels were obtained. The compressive strength in the axial direction was shown to be independent of monolith height and amounted to 2.5 MPa. The hydraulic resistance of the monoliths was an order of magnitude lower than that of granular beds and only weakly dependent on monolith height. Dynamic adsorption experiments with benzene vapor under conditions typical for testing respiratory protective equipment demonstrated that no instantaneous breakthrough of the adsorptive occurred, and the performance of the monoliths was comparable to that of industrial granular activated carbon AG-3.