In recent years, carbon capture and utilization (CCU) has been proposed as a potential technological solution to the problems of greenhouse‐gas emissions and the ever‐growing energy demand. To combat climate change and ocean acidification as a result of anthropogenic CO2 emissions, efforts have already been put forth to capture and sequester CO2 from large point sources, especially power plants; however, the utilization of CO2 as a feedstock to make valuable chemicals, materials, and transportation fuels is potentially more desirable and provides a better and long‐term solution than sequestration. The products of CO2 utilization can supplement or replace chemical feedstocks in the fine chemicals, pharmaceutical, and polymer industries. In this review, we first provide an overview of the current status of CO2‐capture technologies and their associated challenges and opportunities with respect to efficiency and economy followed by an overview of various carbon‐utilization approaches. The current status of combined CO2 capture and utilization, as a novel efficient and cost‐effective approach, is also briefly discussed. We summarize the main challenges associated with the design, development, and large‐scale deployment of CO2 capture and utilization processes to provide a perspective and roadmap for the development of new technologies and opportunities to accelerate their scale‐up in the near future.

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Metal-organic frameworks (MOFs) have shown promising performance in separation, adsorption, reaction, and storage of various industrial gases; however, their large-scale applications have been hampered by the lack of a proper strategy to formulate them into scalable gas-solid contactors. Herein, we report the fabrication of MOF monoliths using the 3D printing technique and evaluation of their adsorptive performance in CO removal from air. The 3D-printed MOF-74(Ni) and UTSA-16(Co) monoliths with MOF loadings as high as 80 and 85 wt %, respectively, were developed, and their physical and structural properties were characterized and compared with those of MOF powders. Our adsorption experiments showed that, upon exposure to 5000 ppm (0.5%) CO at 25 °C, the MOF-74(Ni) and UTSA-16(Co) monoliths can adsorb CO with uptake capacities of 1.35 and 1.31 mmol/g, respectively, which are 79% and 87% of the capacities of their MOF analogues under the same conditions. Furthermore, a stable performance was obtained for self-standing 3D-printed monolithic structures with relatively good adsorption kinetics. The preliminary findings reported in this investigation highlight the advantage of the robocasting (3D printing) technique for shaping MOF materials into practical configurations that are suitable for various gas separation applications.

Structured adsorbents, especially in the form of monolithic contactors, offer an excellent gas-solid contacting strategy for the development of practical and scalable CO capture technologies. In this study, the fabrication of three-dimensional (3D)-printed 13X and 5A zeolite monoliths with novel structures and their use in CO removal from air are reported. The physical and structural properties of these printed monoliths are evaluated and compared with their powder counterparts. Our results indicate that 3D-printed monoliths with zeolite loadings as high as 90 wt % exhibit adsorption uptake that is comparable to that of powder sorbents. The adsorption capacities of 5A and 13X monoliths were found to be 1.59 and 1.60 mmol/g, respectively, using 5000 ppm (0.5%) CO in nitrogen at room temperature. The dynamic CO/N breakthrough experiments show relatively fast dynamics for monolithic structures. In addition, the printed zeolite monoliths show reasonably good mechanical stability that can eventually prevent attrition and dusting issues commonly encountered in traditional pellets and beads packing systems. The 3D printing technique offers an alternative, cost-effective, and facile approach to fabricate structured adsorbents with tunable structural, chemical, and mechanical properties for use in gas separation processes.

One of the main challenges in the power and chemical industries is to remove generated toxic or environmentally harmful gases before atmospheric emission. To comply with stringent environmental and pollutant emissions control regulations, coal-fired power plants must be equipped with new technologies that are efficient and less energy intensive than status quo technologies for flue gas cleanup. While conventional sulfur oxide (SO x ) and nitrogen oxide (NO x ) removal technologies benefit from their large-scale implementation and maturity, they are quite energy intensive. Given this, development of lower cost, less energy intense technologies could offer an advantage. Significant energy and cost savings can be realized using advanced adsorbent materials. One of the major barriers to the development of such technologies remains development of materials that are efficient and productive in removing flue gas contaminates. In this review, adsorption-based removal of SO x /NO x impurities from flue gas is discussed while focusing on important attributes of the solid adsorbent materials as well as implementation of the materials in conventional and emerging acid gas removal technologies. The requirements of effective adsorbents are noted with respect to their performance, key limitations and suggested future research directions. The final section discusses some key areas for future research and provides a possible roadmap for development of more efficient and cost-effective technologies for removal of flue gas impurities than status quo approaches.

Porous solids in the form of adsorbents and catalysts play a crucial role in various industrially important chemical, energy, and environmental processes. Formulating them into structured configurations is a key step toward their scale up and successful implementation at the industrial level. Additive manufacturing, also known as 3D printing, has emerged as an invaluable platform for shape engineering porous solids and fabricating scalable configurations for use in a wide variety of separation and reaction applications. However, formulating porous materials into self-standing configurations can dramatically affect their performance and consequently the efficiency of the process wherein they operate. Toward this end, various research groups around the world have investigated the formulation of porous adsorbents and catalysts into structured scaffolds with complex geometries that not only exhibit comparable or improved performance to that of their powder parents but also address the pressure drop and attrition issues of traditional configurations. In this comprehensive review, we summarize the recent advances and current challenges in the field of adsorption and catalysis to better guide the future directions in shape engineering solid materials with a better control on composition, structure, and properties of 3D-printed adsorbents and catalysts.

Amine-based materials have represented themselves as a promising class of CO adsorbents; however, their large-scale implementation requires their formulation into suitable structures. In this study, we report formulation of aminosilica adsorbents into monolithic structures through a three-dimensional (3D) printing technique. In particular, 3D-printed monoliths were fabricated using presynthesized silica-supported tetraethylenepentamine (TEPA) and poly(ethylenimine) (PEI) adsorbents using three different approaches. In addition, a 3D-printed bare silica monolith was prepared and post-functionalized with 3-aminopropyltrimethoxysilane (APS). Characterization of the obtained monoliths indicated that aminosilica materials retained their characteristics after being extruded into 3D-printed configurations. Adsorptive performance of amine-based structured adsorbents was also investigated in CO capture. Our results indicated that aminosilica materials retain their structural, physical, and chemical properties in the monoliths. In addition, the aminosilica monoliths exhibited adsorptive characteristics comparable to their corresponding powders. This work highlights the importance of adsorbent materials formulations into practical contactors such as monoliths, as the scalabale technology platform, that could facilitate rapid deployment of adsorption-based CO capture processes on commercial scales.

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