Engineering topics

Diaz Aldana, Luis A.

Publications and source records attributed to Diaz Aldana, Luis A..

8 records

DOE OSTI2024

Radiation-assisted electrochemical reduction of CO 2 to CO

Carbon monoxide (CO) is a versatile intermediate feedstock for many applications and can be produced through the electrochemical reduction of carbon dioxide (CO 2 ). However, current electrochemical CO production is hindered by high overall costs, primarily due to low conversion efficiencies and significant energy requirements. Herein, we report a unique way of enhancing the electrochemical reduction of CO 2 to CO using gamma (γ) photons. The γ-irradiation applied to the electrochemical cell setup induces the production of e˙ - , which results in an increased CO 2 ionization and production of excited CO 2 (CO$^{*}_{2}$) molecules via lower energy barrier. The ionized CO 2 ˙ - is quickly stabilized over a silver catalyst, providing an alternative low activation energy route for CO 2 reduction. In conclusion, a decrease in the overpotential barrier enhanced the electrochemical reduction of CO 2 to CO by 25%.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2024

Electrochemical leaching of spent LIBs: Kinetics, novel reactor, and modeling

The use of electrons as main reagent for the recovery and recycling of critical metals from spent lithium-ion batteries (LIBs) is a process electrification strategy that can be used to close the life-cycle loop of LIBs through more sustainable methods. Electrochemical leaching, a process that uses a reductant that is constantly regenerated electrochemically for the leaching of lithium-ion battery black mass (LIBBM), has shown high extraction efficiencies and sustainable scores. However, slow kinetics, reactor design challenges and lack of deeper understanding of the underlying processes are barriers to the optimization, scale-up, and market adoption of this technology. In this paper, a kinetic study and mathematical model for dissolving LIBBM is presented to better understand the underlying mechanisms aiming to reduce the processing time and make predictions for future design and scale-up. The effect of acid and electrochemically mediated reductant concentrations, LIBBM loading, and cathode/reactor designs were explored. As a result, the leaching time was reduced from 7h to under 1h at a pulp density of 73 g/L, without external heating. A novel reactor with parallel baffle electrodes (PBE) was developed, which significantly reduced the leaching time by improving convection in a stirred slurry electrochemical reactor. Dimensionless numbers were deduced from an unsteady state model, which can be used in dimensional analysis for future process design and scale-up.

25 ENERGY STORAGE↗

DOE OSTI2023

Radiation-induced dry reforming: A negative emission process

The reaction between the most abundant greenhouse gases (GHG) to produce hydrogen might represent the most powerful and effective decarbonizing opportunity, if a low-carbon energy source is used to drive it. This is the case of methane (CH 4 ) dry reforming (MDR) where its reaction with carbon dioxide (CO 2 ) produces synthesis gas (syngas, a mixture of carbon monoxide and hydrogen). Here this study explores the feasibility of using ionizing radiation to induce the MDR reaction, at low temperatures and/or less energy demanding conditions. Additionally, the ionizing radiation is proposed to be supplied by nuclear power plants (NPPs), which are low-carbon reliable energy generation sources. Thus, the radiolysis of CO 2 , CH 4 and their mixtures, under ?-irradiation was evaluated in the absence and presence of nickel catalysts. The radiation-induced MDR reaction and radiation-induced catalytic promotion were proven to take place at temperatures close to ambient though at low conversion, with yields below 1%. Since irradiation and heat can be provided by a nuclear power plant, this radiation-induced reaction establishes a connection between nuclear energy to renewable resources and enables a pathway for a decarbonized cleaner chemical industry, for producing green chemicals.

08 HYDROGEN↗

DOE OSTI2023

Effect of chromium on corrosion resistance of Ni-Cr-Mo-Gd alloys in seawater

Neutron absorbing materials are being considered within commercial spent nuclear fuel disposal canisters to maintain nuclear subcriticality in storage. To select candidate alloys for the canisters, both neutron absorption and corrosion resistance should be considered. This work examines corrosion resistance of Ni-Cr-Mo-Gd alloys developed specifically for neutron absorption. The addition of Gd results in a secondary gadolinide phase (Ni 5 Gd) that significantly changes the corrosion properties. Testing was performed primarily in seawater at 30°C. Seawater was selected as the most prevalent terrestrial brine and is characterized by a high chloride concentration. Various electrochemical corrosion techniques were carried out to evaluate Ni-Cr-Mo-Gd alloys with different Cr compositions and investigate the role of Ni 5 Gd phase on corrosion behavior. C22 was included as a benchmark material, due to the similarity in composition and the significant corrosion data available. Here, test results showed a tendency to passivate over time which is attributed to dissolution of surface exposed Ni 5 Gd phase. Cross-sectional analysis indicated that dissolution could penetrate hundreds of micrometers deep under aggressive conditions. It was found that higher Cr variant (21.01%) showed much shallower impact, suggesting Cr prevented primary phase corrosion and thus reduced Ni 5 Gd phase dissolution. Acid pickling of the specimens showed much less dissolution for a higher Cr material and suggested some primary phase dissolution for the low Cr specimen. Acid pickled specimens showed positive shifts in the repassivation potential, suggesting increased surface passivation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Separation of cobalt, nickel, and manganese in leach solutions of waste lithium-ion batteries using Dowex M4195 ion exchange resin

Current methods to separate and recover critical metals from waste lithium-ion battery (LIB) scrap require multiple unit operations that involve selective leaching and a combination of separation methods. These methods include impurity removal, solvent extraction, ion exchange, and precipitation, to achieve high purity Co and Ni products. In this paper an efficient extraction strategy was developed to individually separate Ni and Co from a LIB leachate that was generated from an electrochemical leaching process. By using Dowex M4195 resin, as the only method of separation, additional impurity removal operations were not needed. After loading and eluting, three different fractions were obtained: 99.0% Ni concentrate, 98.5% Co concentrate, and a Li/Mn rich concentrate allowing the separation of Ni, Co and Mn. Here, the developed process is then presented as an alternative for metal recovery from leachates from scrap LIBs with minimum chemical addition and pH adjustment.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Reactor systems for recovering metals, and related methods

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

Lister, Tedd E.↗

DOE OSTI2021

Methods and systems for the electrochemical reduction of carbon dioxide using switchable polarity materials

A method of electrochemically reducing CO2 comprises introducing a first feed stream comprising H2O to a positive electrode of an electrolysis cell comprising the positive electrode, a negative electrode, and a proton conducting membrane. A second feed stream comprising a solvent and a non polar form of a switchable polarity material is directed into a CO2 capture apparatus. A third feed stream comprising CO2 is directed into the CO2 capture apparatus to interact with the second feed stream and form a first product stream comprising the solvent and a polar form of the switchable polarity material. The first product stream is introduced to the negative electrode. A potential difference is applied between the positive electrode and the negative electrode to convert the polar form of the switchable polarity material into CO2 and the non-polar form and to form products from the CO2 and the solvent. A CO2 treatment system is also described.

Lister, Tedd E.↗

DOE OSTI2020

Intensified Co-electrolysis Process for Syngas Production from Captured CO 2

CO 2 reduction to syngas provides a way of ameliorating carbon footprint and storing energy in high-energy-density and versatile feedstock. This current work explores the isothermal integration of CO2 capture with an intensified unit operation for the reduction of CO2 and capture media regeneration. Intensified captured CO2 co-electrolysis (ICC) to syngas (H2:CO ratio of 2) with low CO2 content (<10%) was demonstrated with over 70% CO2 conversion at a current density up to 0.20 A/cm2 for 14 hours of operation. Integration of the co-electrolysis unit with CO2 capture was performed feeding pure and diluted CO2, for which CO2 conversions >65% were observed. Performance of the capture unit becomes critical to maintain syngas ratios (SR). Technology feasibility was assessed through comparative techno-economic and life cycle analysis showing that process intensification enables competitive performance, even at the higher energy consumption featured at the current state of the technology. This because several unit operations can be avoided. LCA also showed that based on the current US electricity mix the reduction of life cycle CO2 emissions is possible at scenarios observed with 0.15 A/cm2 to accomplish a carbon-negative technology.

08 HYDROGEN↗