Stanford Advisors

All Publications

  • Tuning sorbent properties to reduce the cost of direct air capture ENERGY & ENVIRONMENTAL SCIENCE Holmes, H. E., Banerjee, S., Vallace, A., Lively, R. P., Jones, C. W., Realff, M. J. 2024

    View details for DOI 10.1039/d4ee00616j

    View details for Web of Science ID 001243234400001

  • Guanidine-Functionalized PIM-1 as a High-Capacity Polymeric Sorbent for CO<sub>2</sub> Capture CHEMISTRY OF MATERIALS Roy, A., Holmes, H. E., Baugh, L., Calabro, D. C., Leisen, J., Seth, S., Ren, Y., Weston, S. C., Lively, R. P., Finn, M. G. 2024
  • Cold Temperature Direct Air CO2 Capture with Amine-Loaded Metal-Organic Framework Monoliths. ACS applied materials & interfaces Wang, Y., Rim, G., Song, M., Holmes, H. E., Jones, C. W., Lively, R. P. 2024; 16 (1): 1404-1415


    Zeolites, silica-supported amines, and metal-organic frameworks (MOFs) have been demonstrated as promising adsorbents for direct air CO2 capture (DAC), but the shaping and structuring of these materials into sorbent modules for practical processes have been inadequately investigated compared to the extensive research on powder materials. Furthermore, there have been relatively few studies reporting the DAC performance of sorbent contactors under cold, subambient conditions (temperatures below 20 °C). In this work, we demonstrate the successful fabrication of adsorbent monoliths composed of cellulose acetate (CA) and adsorbent particles such as zeolite 13X and MOF MIL-101(Cr) by a 3D printing technique: solution-based additive manufacturing (SBAM). These monoliths feature interpenetrated macroporous polymeric frameworks in which microcrystals of zeolite 13X or MIL-101(Cr) are evenly distributed, highlighting the versatility of SBAM in fabricating monoliths containing sorbents with different particle sizes and density. Branched poly(ethylenimine) (PEI) is successfully loaded into the CA/MIL-101(Cr) monoliths to impart CO2 uptakes of 1.05 mmol gmonolith-1 at -20 °C and 400 ppm of CO2. Kinetic analysis shows that the CO2 sorption kinetics of PEI-loaded MIL-101(Cr) sorbents are not compromised in the monoliths compared to the powder sorbents. Importantly, these monoliths exhibit promising working capacities (0.95 mmol gmonolith-1) over 14 temperature swing cycles with a moderate regeneration temperature of 60 °C. Dynamic breakthrough experiments at 25 °C under dry conditions reveal a CO2 uptake capacity of 0.60 mmol gmonolith-1, which further increases to 1.05 and 1.43 mmol gmonolith-1 at -20 °C under dry and humid (70% relative humidity) conditions, respectively. Our work showcases the successful implementation of SBAM in making DAC sorbent monoliths with notable CO2 capture performance over a wide range of sorption temperatures, suggesting that SBAM can enable the preparation of efficient sorbent contactors in various form factors for other important chemical separations.

    View details for DOI 10.1021/acsami.3c13528

    View details for PubMedID 38109480

    View details for PubMedCentralID PMC10788822

  • Water management and heat integration in direct air capture systems Nature Chemical Engineering Holmes, H. E., Realff, M. J., Lively, R. P. 2024; 1: 208-215
  • Evaluating degradation of CO<sub>2</sub> adsorbents in flue gas from bioenergy with carbon capture and storage SUSTAINABLE ENERGY & FUELS Holmes, H. E., Schreck, R. D., Narayanan, P., Ghosh, S., Sun, W., Realff, M. J., Lively, R. P. 2023; 7 (18): 4602-4607

    View details for DOI 10.1039/d3se00823a

    View details for Web of Science ID 001049276400001

  • Scalable Formation of Diamine-Appended Metal-Organic Framework Hollow Fiber Sorbents for Postcombustion CO2 Capture. JACS Au Quan, W., Holmes, H. E., Zhang, F., Hamlett, B. L., Finn, M. G., Abney, C. W., Kapelewski, M. T., Weston, S. C., Lively, R. P., Koros, W. J. 2022; 2 (6): 1350-1358


    We describe a straightforward and scalable fabrication of diamine-appended metal-organic framework (MOF)/polymer composite hollow fiber sorbent modules for CO2 capture from dilute streams, such as flue gas from natural gas combined cycle (NGCC) power plants. A specific Mg-MOF, Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate), incorporated into poly(ether sulfone) (PES) is directly spun through a conventional "dry-jet, wet-quench" method. After phase separation, a cyclic diamine 2-(aminomethyl)piperidine (2-ampd) is infused into the MOF within the polymer matrix during postspinning solvent exchange. The MOF hollow fibers from direct spinning contain as high as 70% MOF in the total fibers with 98% of the pure MOF uptake. The resulting fibers exhibit a step isotherm and a "shock-wave-shock" breakthrough profile consistent with pure 2-ampd-Mg2(dobpdc). This work demonstrates a practical method for fabricating 2-ampd-Mg2(dobpdc) fiber sorbents that display the MOF's high CO2 adsorption capacity while lowering the pressure drop during operation.

    View details for DOI 10.1021/jacsau.2c00029

    View details for PubMedID 35783169

    View details for PubMedCentralID PMC9241006

  • Defining Targets for Adsorbent Material Performance to Enable Viable BECCS Processes. JACS Au Holmes, H. E., Lively, R. P., Realff, M. J. 2021; 1 (6): 795-806


    Target properties of CO2 capture adsorbents that would ensure economic viability of bioenergy with carbon capture and storage (BECCS) are defined. The key role of sorbent lifetime in the process cost is demonstrated, and an optimal heat of adsorption for BECCS is postulated through a balance of adsorbent-adsorbate affinity and regeneration energy demand. Using an exponential decay model of sorbent capacity increases the process cost and results in an optimum sorbent lifetime. To ensure a levelized cost of carbon below $100/tonne-CO2, adsorbents should be designed to have working capacities above 0.75 mol/kg, lifetimes over 2 years, heats of adsorption of approximately -40 kJ/mol, and exponential degradation decay constants below 5 × 10-6 cycle-1 (equivalent to a half-life of 1.3 years). Our model predicts a BECCS process cost of $65/t-CO2 can be achieved with a degradation-resistant adsorbent, $40/kg sorbent cost, 2.0 mol/kg working capacity, -40 kJ/mol heat of adsorption, and at least a 2 year lifetime.

    View details for DOI 10.1021/jacsau.0c00127

    View details for PubMedID 34467333

    View details for PubMedCentralID PMC8395626

  • Potential Dependence of the Local pH in a CO<sub>2</sub> Reduction Electrolyzer ACS CATALYSIS Henckel, D. A., Counihan, M. J., Holmes, H. E., Chen, X., Nwabara, U. O., Verma, S., Rodriguez-Lopez, J., Kenis, P. A., Gewirth, A. A. 2021; 11 (1): 255-263