High-Productivity Single-Pass Electrochemical Birch Reduction of Naphthalenes in a Continuous Flow Electrochemical Taylor Vortex Reactor.

We report the development of a single-pass electrochemical Birch reduction carried out in a small footprint electrochemical Taylor vortex reactor with projected productivities of >80 g day-1 (based on 32.2 mmol h-1), using a modified version of our previously reported reactor [Org. Process Res. Dev. 2021, 25, 7, 1619-1627], consisting of a static outer electrode and a rapidly rotating cylindrical inner electrode. In this study, we used an aluminum tube as the sacrificial outer electrode and stainless steel as the rotating inner electrode. We have established the viability of using a sacrificial aluminum anode for the electrochemical reduction of naphthalene, and by varying the current, we can switch between high selectivity (>90%) for either the single ring reduction or double ring reduction with >80 g day-1 projected productivity for either product. The concentration of LiBr in solution changes the fluid dynamics of the reaction mixture investigated by computational fluid dynamics, and this affects equilibration time, monitored using Fourier transform infrared spectroscopy. We show that the concentrations of electrolyte (LiBr) and proton source (dimethylurea) can be reduced while maintaining high reaction efficiency. We also report the reduction of 1-aminonaphthalene, which has been used as a precursor to the API Ropinirole. We find that our methodology produces the corresponding dihydronaphthalene with excellent selectivity and 88% isolated yield in an uninterrupted run of >8 h with a projected productivity of >100 g day-1.

Environmental Aspects of Use of Recycled Carbon Fiber Composites in Automotive Applications.

The high cost and energy intensity of virgin carbon fiber manufacture provides an opportunity to recover substantial value from carbon fiber reinforced plastic wastes. In this study, we assess the life cycle environmental implications of recovering carbon fiber and producing composite materials as substitutes for conventional and proposed lightweight materials in automotive applications (e.g., steel, aluminum, virgin carbon fiber). Key parameters for the recycled carbon fiber materials, including fiber volume fraction and fiber alignment, are investigated to identify beneficial uses of recycled carbon fiber in the automotive sector. Recycled carbon fiber components can achieve the lowest life cycle environmental impacts of all materials considered, although the actual impact is highly dependent on the design criteria (λ value) of the specific component. Low production impacts associated with recycled carbon fiber components are observed relative to lightweight competitor materials (e.g., aluminum, virgin carbon fiber reinforced plastic). In addition, recycled carbon fiber components have low in-use energy use due to mass reductions and associated reduction in mass-induced fuel consumption. The results demonstrate environmental feasibility of the CFRP recycling materials, supporting the emerging commercialization of CF recycling technologies and identifying significant potential market opportunities in the automotive sector.

Continuous Photo-Oxidation in a Vortex Reactor: Efficient Operations Using Air Drawn from the Laboratory.

We report the construction and use of a vortex reactor which uses a rapidly rotating cylinder to generate Taylor vortices for continuous flow thermal and photochemical reactions. The reactor is designed to operate under conditions required for vortex generation. The flow pattern of the vortices has been represented using computational fluid dynamics, and the presence of the vortices can be easily visualized by observing streams of bubbles within the reactor. This approach presents certain advantages for reactions with added gases. For reactions with oxygen, the reactor offers an alternative to traditional setups as it efficiently draws in air from the lab without the need specifically to pressurize with oxygen. The rapid mixing generated by the vortices enables rapid mass transfer between the gas and the liquid phases allowing for a high efficiency dissolution of gases. The reactor has been applied to several photochemical reactions involving singlet oxygen (1O2) including the photo-oxidations of α-terpinene and furfuryl alcohol and the photodeborylation of phenyl boronic acid. The rotation speed of the cylinder proved to be key for reaction efficiency, and in the operation we found that the uptake of air was highest at 4000 rpm. The reactor has also been successfully applied to the synthesis of artemisinin, a potent antimalarial compound; and this three-step synthesis involving a Schenk-ene reaction with 1O2, Hock cleavage with H+, and an oxidative cyclization cascade with triplet oxygen (3O2), from dihydroartemisinic acid was carried out as a single process in the vortex reactor.

Recycling supercapacitors based on shredding and mild thermal treatment.

Supercapacitors are widely used in electric and hybrid vehicles, wind farm and low-power equipment due to their high specific power density and huge number of charge-discharge cycles. Waste supercapacitors should be recycled according to EU directive 2002/96/EC on waste electric and electronic equipment. This paper describes a recycling approach for end-of-life supercapacitors based on shredding and mild thermal treatment. At first, supercapacitors are shredded using a Retsch cutting mill. The shredded mixture is then undergone thermal treatment at 200°C to recycle the organic solvent contained in the activated carbon electrodes. After the thermal treatment, the mixture is roughly separated using a fluidized bed method to remove the aluminium foil particles and paper particles from the activated carbon particles, which is subsequently put into water for a wet shredding into fine particles that can be re-used. The recycled activated carbon has a BET surface area of up to 1200m(2)/g and the recycled acetonitrile has a high purity.