Engineering topics
Vlachos, Dionisios (ORCID:0000000267958403)
Publications and source records attributed to Vlachos, Dionisios (ORCID:0000000267958403).
Assessing the Binding of Plastics Additives at Brønsted Acid Sites of Zeolites
Not provided.
Chemical recycling of mixed textile waste
Globally, less than 0.5% of postconsumer textile waste is recycled, with the majority incinerated or ending up in landfills. Most postconsumer textiles are mixed fibers, complicating mechanical recycling due to material blends and contaminants. Here, we demonstrate the chemical conversion of postconsumer mixed textile waste using microwave-assisted glycolysis over a ZnO catalyst followed by solvent dissolution. This approach electrifies the process heat while allowing rapid depolymerization of polyester and spandex to their monomers in 15 minutes. A simple solvent dissolution enables the separation of cotton and nylon. We assess the quality of all components through extensive material characterization, discuss their potential for sustainable recycling, and provide a techno-economic analysis of the economic feasibility of the process.
Biphasic Plasma Microreactor for Oxyfunctionalization of Liquid Hydrocarbons
Not provided.
Theoretical Insights into H 2 Activation over Anatase TiO 2 Supported Metal Adatoms
Not provided.
Synthesis of Long Chain Oxygenates via Aldol Condensation of Furfural and Acetone over Metal–Organic Frameworks
Not provided.
Plasma-Enabled Ligand Removal for Improved Catalysis: Furfural Conversion on Pd/SiO 2
Not provided.
Direct Brønsted Acid-Catalyzed Dehydration of Glucose to HMF in Methyl Isobutyl Ketone
Not provided.
A two-stage strategy for upcycling chlorine-contaminated plastic waste
Abstract Chemical upcycling of polyolefin plastic waste to lubricant, wax and fuel-range hydrocarbons over metal-based catalysts is a crucial technological solution to the enormous environmental threat posed by plastic waste. However, currently available methods are incompatible with chlorine-contaminated feedstocks. Here we report a two-stage strategy for upcycling chlorine-contaminated polypropylene. First, magnesia–alumina mixed oxide at 30 bar H 2 and 250 °C serves as a chlorine trap by rapidly forming solid chloride, resulting in nearly complete chlorine extraction from the polyolefin melt. This enables the upcycling of plastic waste with up to 10% polyvinyl chloride content to lubricants over ruthenium-based catalysts, in the second stage. The strategy is also applicable to chlorinated aromatics and alkanes. The proposed strategy renders hydrocracking and hydrogenolysis catalysts less sensitive to the chlorine impurities in feedstocks while eliminating HCl emissions and chlorine contamination in products. It could incentivize further progress in plastics upcycling.
Scale-up preparation, column chromatography-free purification of protected carbonyl-containing biomass molecules and their derivatizations
An efficient, column chromatography-free route for scale-up preparation of protected carbonyl containing biomass molecules is established. Then the protection group effect is investigated in multiple systems especially under a reducing atmosphere.
Understanding solvent effects on adsorption and protonation in porous catalysts
Abstract Solvent selection is a pressing challenge in developing efficient and selective liquid phase catalytic processes, as predictive understanding of the solvent effect remains lacking. In this work, an attenuated total reflection infrared spectroscopy technique is developed to quantitatively measure adsorption isotherms on porous materials in solvent and decouple the thermodynamic contributions of van der Waals interactions within zeolite pore walls from those of pore-phase proton transfer. While both the pore diameter and the solvent identity dramatically impact the confinement (adsorption) step, the solvent identity plays a dominant role in proton-transfer. Combined computational and experimental investigations show increasingly favorable pore-phase proton transfer to pyridine in the order: water < acetonitrile < 1,4 – dioxane. Equilibrium methods unaffected by mass transfer limitations are outlined for quantitatively estimating fundamental thermodynamic values using statistical thermodynamics.