3D-printed adsorbents for gas separations: A material development, kinetic assessment, and process performance investigation

“Adsorbent materials are promising for various gas purification processes, however, forming them into structured contactors is paramount in enhancing mass transfer properties and reducing pressure losses. In this research, various adsorbents were engineered into structured contactors with 3D printing. The overall goal of this research was to improve the formulation methods of 3D-printed adsorbents and understand their performances in gas separation processes. The specific objectives were to 1) develop new adsorbent 3D-printing strategies, 2) understand the kinetic properties of printed adsorbent monoliths, and 3) assess their process performances. Objective one was addressed by developing five 3D printing techniques: i) oxide seeding and secondary MOF growth (Paper I), ii) direct ink writing of amine-modified MOFs (Paper II), iii) polymer seeding with MOF growth (Paper III), IV) MOF precursor incorporation into printable sol-gels with thermal coordination (Paper V), and v) binderless zeolite printing with sacrificial pectin and gelatin biopolymers (Paper VI). Objective two was addressed by varying the monolith cell density (Paper IV), adsorbent loading method (Papers II-III, V-VI) and macropore space (Paper IV-VI) to determine how these properties relate to printed monoliths’ mass transfer rates. Objective three was addressed by varying the process conditions in a PSA system over a 3D-printed MOF-74 (Ni) monolith for CO2/H2 separation (Paper VII) and over an activated carbon monolith bed for CO2/CH4 separation (Paper VIII). Overall, this research indicated that developing new printing methods can enhance the physiochemical and kinetic properties of printed adsorbent monoliths, established that printed monoliths’ kinetic rates are limited by molecular diffusion, and demonstrated that printed adsorbent monoliths can achieve comparable PSA separation performance to established benchmarks”--Abstract, page iv