Martha A. Arellano Treviño

Scaling conventional carbon capture and utilization methods can be limited by cost and permitting issues associated with transportation of captured CO2. Reactive carbon capture (RCC), in which a single solid-phase dual function material (DFM) is used to both capture CO2 from dilute streams (e.g., flue gas) and catalytically convert the bound species to products in a single unit operation, has the potential to reduce energy and capital costs by over 50% relative to separate capture and conversion. To incentivize adoption, high-value products such as methanol and CO should be targeted. Appealingly, CO can be produced at atmospheric pressure, thereby lowering overall H2 demand; however, high reaction temperatures (> 600 degrees C) and the use of oxidizable transition metals, such as Ni, are often necessary to drive the reverse water-gas shift (RWGS) during reactive desorption of the bound CO2. The sensitivity of these transition metals to oxygen undercuts their utility in point source RCC. To further derisk RCC, it is essential to develop metallic-phase free DFMs that are insensitive to residual oxygen in flue gas and can achieve selective reactive desorption to CO at moderate pressures (< 400 degrees C). To this end, we have developed K-modified Zn-Al mixed oxides (K/ZnAlOx) to convert captured CO2 to CO with > 97% selectivity and yields up to 53% of captured CO2 at 400 degrees C. Complementary in situ spectroscopy studies revealed the role of K-modification in improving RCC performance of unmodified ZnAlOx. The top performing DFM was also subjected to extended RCC cycling with oxygen co-fed with CO2 during the capture test to assess durability under simulated flue gas.

The goals of this project are to design and develop tailored dual-functional materials (DFMs) and the accompanying pressure-swing process for the reactive capture and conversion (RCC) of CO2 to methanol, a vital product in the chemical market and a versatile precursor to fuels. Throughout this project, NREL researcher team has successfully developed 2 groups of DFM and associated cyclic RCC procedure to selectivity produce either methanol or CO, which is a major intermediate for methanol synthesis with commercially available technologies. Additionally, this project has also developed process models and techno-economic analysis (TEA) and life cycle assessment (LCA) framework to evaThe goals of this project are to design and develop tailored dual-functional materials (DFMs) and the accompanying pressure-swing process for the reactive capture and conversion (RCC) of CO2 to methanol, a vital product in the chemical market and a versatile precursor to fuels. The proposed approach is based on the hypothesis that precise co-location of basic and metallic sites in a DFM will enable efficient RCC of CO2 in a fixed-bed temperature-pressure-swing reactor under mild conditions that favor lower capital and operating expenses and offer compatibility with a dynamic energy grid to provide favorable process economics. The proposed hybrid process utilizes renewable H2 and targets deployment at a gas-fired power plant, where CO2 point sources have relatively high CO2 capture costs by traditional methods, ranging from 43 to 89 $/ton, suggesting that the economics would benefit from an RCC approach. This choice of CO2 source represents a relatively lower carbon capture rate (0.47 MMTCO2 per plant year), but with a high number of plants (>1100). This deployment plan holds the potential to achieve relevant carbon capture and utilization magnitudes through modular implementation of the process, where initial estimates suggest that the current annual production rate of renewable methanol (0.2 MMT/year) could be equaled upon the first installation of the proposed technology. Throughout this project, NREL researcher team has successfully developed 2 groups of DFM and associated cyclic RCC procedure to selectivity produce either methanol or CO, which is a major intermediate for methanol synthesis with commercially available technologies. Additionally, this project has also developed process models and techno-economic analysis (TEA) and life cycle assessment (LCA) framework to evaluate feasibility of the developed DFM and processes. The TEA/LCA framework includes integration of RCC process models developed using ASPEN Plus and optimization of renewable hydrogen generation and supply for RCC process using NREL's developed H2INTEGRATE tool. The detailed results of this project are reported below in 3 major sections: 1. Development of DFM for RCC to produce methanol; 2. Development of DFM for RCC to produce CO; 3. Development of TEA and LCA framework for technology feasibility evaluation. Additionally, major milestone achievements are summarized in section 4 with scientific products, including publications, patents, posters and presentations are listed in section 5. Section 6 provides a quarterly budget summary for the project.

We develop a catalytic process comprising exclusively of flow reactions for conversion of wet waste-derived volatile fatty acids to sustainable aviation fuel (SAF) and key aromatic building blocks (benzene, toluene, ethylbenzene, and xylene; BTEX). Acids are upgraded via sequential ketonization and either cyclization of light (C_3-7) ketones to BTEX and an aromatic SAF blendstock or hydrodeoxygenation of C₈₊ ketones to an alkane SAF blendstock. The enabling step investigated in this work is light ketone cyclization over H/ZSM-5, which was chosen through screening upgrading of 4-heptanone over solid acidic and basic catalysts. We then determined the reaction network of 4-heptanone upgrading by analyzing selectivity trends with conversion and concluded that the reaction should be run at full conversion. Finally, we demonstrated the entire acid upgrading process by converting commercial food waste-derived carboxylic acids to SAF blendstocks and BTEX. We blended the C₉₊ aromatic and alkane products to create one SAF blendstock and show that this mixture can be blended 50/50 with Jet A and meet all critical property standards. Techno-economic analysis and life cycle assessment show that utilizing a food waste feedstock for the process can be economically feasible with current policy incentives and reduce greenhouse gas emissions by more than 250%.

A novel RCC process using modified CZA DFMs to produce renewable MeOH is presented. K/CZA provides exceptionally high productivity of MeOH compared to previously reported attempts of RCC to MeOH.