Carbon neutral manufacturing via on-site CO2 recycling

The chemical industry needs to significantly decrease carbon dioxide (CO₂) emissions in order to meet the 2050 carbon neutrality goal. Utilization of CO₂ as a chemical feedstock for bulk products is a promising way to mitigate industrial emissions; however, CO₂-based manufacturing is currently not competitive with the established petrochemical methods and its deployment requires creation of a new value chain. Here, we show that an alternative approach, using CO₂ conversion as an add-on to existing manufactures, can disrupt the global carbon cycle while minimally perturbing the operation of chemical plants. Proposed closed-loop on-site CO₂ recycling processes are economically viable in the current market and have the potential for rapid introduction in the industries. Retrofit-based CO₂ recycling can reduce annually between 4 and 10 Gt CO₂ by 2050 and contribute to achieving up to 50% of the industrial carbon neutrality goal.

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CO₂ electroconversion is a feasible retrofit for petrochemical plants

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On-site recycling removes several barriers against large-scale CO₂ processing

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CO₂ recycling concept is economically viable in the current market

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On-site recycling has potential to remove 4–10 Gt of CO₂ emissions annually by 2050

Rational Design of Perovskite-Based Anode with Decent Activity for Hydrogen Electro-Oxidation and Beneficial Effect of Sulfur for Promoting Power Generation in Solid Oxide Fuel Cells

The poor sulfur tolerance of conventional nickel cermet anodes is particularly concerning for solid oxide fuel cell technology. Herein, we report an innovative anode composed of a samaria-doped ceria (SDC) scaffold and a perovskite La_0.35Ca_0.50TiO_3-δ thin film with a surface modified with strongly coupled and in situ-formed Ni nanoparticles; the anode was prepared via an infiltration-calcination-reduction method. The rational design of such an anode transforms the detrimental effect of sulfur on the cell performance (poisoning) of state-of-the-art Ni cermet anodes into a beneficial effect promoting power generation from H₂. A cell with a Ni + SDC cermet anode and a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ cathode showed an 18.3% reduction in the power output at 800 °C when the fuel gas was switched from pure H₂ to H₂-1000 ppm H₂S, while a similar cell with this innovative anode showed a power output enhancement of 6.6%. Furthermore, the operational stability was significantly improved. The perovskite phase was found to account for the improved cell power output in the presence of sulfur impurity. The introduction of the nickel nanoparticles further significantly enhanced the electrode activity, while the strong coupling effect of exsolved nickel nanoparticles with the perovskite thin film improved the sulfur tolerance of the nickel phase. As a result, the anode showed both high activity and stability while operating on H₂ fuel with high concentration of H₂S (1000 ppm). The promoting effect of sulfur on the power generation over the perovskite anode is also discussed.

Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration

Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

Sulfur-tolerant redox-reversible anode material for direct hydrocarbon solid oxide fuel cells

A novel composite anode material consisting of K(2) NiF(4) -type structured Pr(0.8) Sr(1.2) (Co,Fe)(0.8) Nb(0.2) O(4+δ) (K-PSCFN) matrix with homogenously dispersed nano-sized Co-Fe alloy (CFA) has been obtained by annealing perovskite Pr(0.4) Sr(0.6) Co(0.2) Fe(0.7) Nb(0.1) O(3-δ) (P-PSCFN) in H(2) at 900 °C. The K-PSCFN-CFA composite anode is redox-reversible and has demonstrated similar catalytic activity to Ni-based cermet anode, excellent sulfur tolerance, remarkable coking resistance and robust redox cyclability.

Electronic and vibrational properties of nickel sulfides from first principles

We report the results of first-principles calculations (generalized gradient approximation-Perdew Wang 1991) on the electronic and vibrational properties of several nickel sulfides that are observed on Ni-based anodes in solid oxide fuel cells (SOFCs) upon exposure to H2S contaminated fuels: heazlewoodite Ni3S2, millerite NiS, polydymite Ni3S4, and pyrite NiS2. The optimized lattice parameters of these sulfides are within 1% of the values determined from x-ray diffraction. The electronic structure analysis indicates that all Ni-S bonds are strongly covalent. Furthermore, it is found that the nickel d orbitals shift downward in energy, whereas the sulfur p orbitals shift upward with increasing sulfur content; this is consistent with the decrease in conductivity and catalytic activity of sulfur-contaminated Ni-based electrodes (or degradation in SOFC performance). In addition, we systematically analyze the classifications of the vibrational modes at the point from the crystal symmetry and calculate the corresponding vibrational frequencies from the optimized lattice constants. This information is vital to the identification with in situ vibrational spectroscopy of the nickel sulfides formed on Ni-based electrodes under the conditions for SOFC operation. Finally, the effect of thermal expansion on frequency calculations for the Ni3S2 system is also briefly examined.