Enhanced Catalytic Hydrodeoxygenation of Activated Carbon-Supported Metal Catalysts via Rapid Plasma Surface Functionalization

Efficient remediation and synchronous recovery of uranium by phosphate-functionalized magnetic carbon-based flow electrode capacitive deionization

Through the design of flow electrodes, flow electrode capacitive deionization (FCDI) enables the efficient remediation of uranium-contaminated water to meet World Health Organization (WHO) standards (uranium ≤ 30 ppb), while concurrently facilitating the recovery of uranium from the flow electrode slurry. In this work, the phosphate-functionalized magnetic carbon-based flow electrode (OMPAC) was synthesized by simply co-precipitation and oxygen plasma treatment. The enhanced conductivity of OMPAC accelerated the efficient remediation of surface water contaminated with multiple nuclides, due to the improved charge-transfer capability facilitated by the introduced magnetic particles (Fe, Fe3O4, Fe3C) and heteroatoms (O, P). The uranium in feed solution was selectively adsorbed by OMPAC in flow electrode slurry, benefiting from the multiple strong sorption interactions between U(VI) and C=O/P=O/P-O groups, as well as the redox reactions between U(VI) and Fe (0/II). After four batch cycles, the average uranium removal rate by OMPAC was maintained at 97.84 %, while the recovery rate of uranium from OMPAC reached 78.2 %, demonstrating the excellent long-term performance and synchronous uranium recovery capability in FCDI. This study provides feasibility guidance for the remediation of radioactive pollution and the strategic reuse of resources via the FCDI technology.

Catalytic Hydrodeoxygenation of Phenols and Cresols to Gasoline Range Biofuels

Unlike fossil fuels, biomass has oxygen amounts exceeding 10 wt%. Hydrodeoxygenation (HDO) is a crucial step in upgrading biomass to higher heating value liquid fuels. Oxygen removal has many challenges due to the complex chemistry and the high reactivity leading to irreversible catalyst deactivation. In this study, the focus is on the catalytic HDO of aromatic oxygen-containing model compounds in biomass: phenols and cresols. In the current work, literature on catalytic HDO of phenols using molecular hydrogen is reviewed, with a focus on non-nickel-based mono- and bi-metallic catalysts, as nickel-based catalysts were reviewed elsewhere. In addition, the catalytic HDO of m-cresol using molecular hydrogen is examined. This review also addresses the use of hydrogen donors for the HDO of phenols and cresols. The operating conditions, catalysts, products, and yields are summarized to find the catalyst with promising activity and high selectivity toward aromatics. A critical review of the reactions that successfully led to HDO is presented and research gaps related to the HDO of phenols and cresols are highlighted. The conclusions provide potential successful catalyst combinations that can be used for HDO of phenols, cresols, and liquid aromatic hydrocarbons.

Influence of Brönsted Acid Sites on Activated Carbon-Based Catalyst for Acetylene Dimerization

Activated carbon (AC) has been widely used as a support material with both tunable acidity and abundant functional groups for solid acid catalysts in various chemical processes such as acetylene dimerization. A facile, mild acid modification method that directly activates AC to generate rich defects and oxygen functional group surface structures with Brönsted acid sites and an enhanced conductivity is presented here. Impressively, the catalyst with optimized Brönsted acid sites and an enhanced dispersion of active components exhibited a superior acetylene dimerization catalytic activity. Moreover, theoretical calculations indicated that an increase in hydrogen concentration could inhibit the formation of coke. This research offered a feasible potential way to devise and construct a carbon-based solid acid catalyst with an excellent catalytic performance.

Plasma-Enabled Ligand Removal for Improved Catalysis: Furfural Conversion on Pd/SiO2

A nonthermal, atmospheric He/O2 plasma (NTAP) successfully removed polyvinylpyrrolidone (PVP) from Pd cubic nanoparticles supported on SiO2 quickly and controllably. Transmission electron microscopy (TEM) revealed that the shape and size of Pd nanoparticles remain intact during plasma treatment, unlike mild calcination, which causes sintering and polycrystallinity. Using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), we demonstrate the quantitative estimation of the PVP plasma removal rate and control of the nanoparticle synthesis. First-principles calculations of the XPS and CO FTIR spectra elucidate electron transfer from the ligand to the metal and allow for estimates of ligand coverages. Reactivity testing indicated that PVP surface crowding inhibits furfural conversion but does not alter furfural selectivity. Overall, the data demonstrate NTAP as a more efficient method than traditional calcination for organic ligand removal in nanoparticle synthesis.