Green Chemical Engineering最新文献

The paper presents research results of the synthesis, phase composition, and structure of products obtained by highly exothermic reactions between Ti and C₁₀H₈O₄ mixture components, depending on the plastic waste concentration and Ti powder dispersiveness, density of initial samples, and synthesis medium. The dependence of the phase composition and structure of the synthesis products on the concentration of the polymer (plastic) component in the initial Ti -PET (C₁₀H₈O₄) system was found. When the plastic waste content is 20 wt% to 25 wt%, synthesis products contain TiC_0.5O_0.5–TiC_0.6–0.75 particle agglomerates. Further growth in the polyethylene terephthalate content from 30 wt% to 45 wt% leads to the formation of synthesis products consisting of titanium carbide (TiC_0.6–1.0). The gaseous byproduct composition of the exothermic reaction is investigated for the Ti–C₁₀H₈O₄ mixture composition. It is found that the gaseous by-product mostly contains hydrogen and carbon monoxide as well as impurities of different hydrocarbons (methane, acetylene, ethane, ethene) and carbon dioxide. The maximum adiabatic temperature of the gas combustion temperature is 2080 ^oC, which demonstrates the possibility of using gas as a fuel for energy generation devices. Based on the data obtained, it is possible to create a basis for a new plastic waste technology to fabricate carbide-containing materials.

Conventional thermosetting polymers, mostly derived from nonrenewable petroleum resources, are not reprocessable and recyclable due to their highly cross-linked three-dimensional networks and face the disadvantage of high flammability. To solve these issues, in this study, we synthesized a novel Schiff base covalent adaptable thermoset from a furan-derived tri-aldehyde monomer (TMFP) and a furan-derived di-amine monomer (DFDA). The as-prepared TMFP-DFDA-Vitrimer exhibited superior anti-flammability with a high limiting oxygen index (LOI) of 35.0% and a UL-94 V-0 rating, which was attributed to the excellent charring ability. Additionally, TMFP-DFDA-Vitrimer could also be conveniently recycled by chemical decomposition under a mixed hydrochloric acid/tetrahydrofuran (HCl/THF) solution. After recycling for 5 times, the thermal, mechanical, and flame retardant properties of the recycled TMFP-DFDA-Vitrimer retained almost unchanged compared to the original one. This work provides a prime instance to develop advanced thermosetting polymers from abundant furan-based compounds.

The burgeoning field of photocatalytic reduction of CO₂ has emerged as a remarkable promising solution to address some of the most pressing global energy and environmental issues which we face today. Researchers around the global have been striving to augment the efficiency of CO₂ photocatalytic reduction, employing strategies that range from modifying the fundamental properties of photocatalysts to suppress the electron-hole recombination, optimizing reaction conditions to achieve the highest yield, and conceptualizing and constructing photoreactors to improve the adsorption process. Among these factors, the photoreactor plays a critical role in enhancing the overall photocatalytic efficiency. Understanding the various types of photoreactors and their operational dynamic can significantly influence the experimental design, thus guiding the data collecting and analysis. Compared to the solid-liquid phase, gas-solid phase photocatalytic reduction of CO₂ is gaining recognition for its potential advantages, such as rapid molecular diffusion rates, adjustable CO₂ concentrations, and uniform and sufficient light exposure. Nonetheless, the currently reported gas-solid phase photoreactors are still in their infancy. In this review, we dissect the underlying mechanism of photocatalytic CO₂ reduction and the performance evaluation criteria of photoreactors, and review the development process of gas-solid phase photoreactors. Furthermore, we explore the evolution of gas-solid phase photoreactors, elucidating their growth trajectory and future possibilities. We present a comprehensive classification of gas-solid phase photoreactors, offering a new insight into their design and functionality, summarizing their strengths and inevitable limitations. Finally, we provide a forward-looking perspective on the future developmental prospects of carbon neutrality.

Benzene alkylation catalyzed by immobilized ionic liquids (ILs) on solid carriers is considered as a heterogeneous reaction, in which the interfacial properties play an important role. Hence, the interfacial characteristics between benzene/1-dodecene mixture and immobilized chloroaluminate ILs with different alkyl chain length on the silica substrate were investigated by molecular dynamics simulation. The grafted ILs can obviously promote the enrichment of benzene near the interface, leading to a higher ratio of benzene to dodecene, and the interfacial width increases slightly with increased alkyl chain of grafted cations. At the same time, the grafted cations can also enhance the benzene diffusion and suppress the dodecene diffusion at the interface, which probably helps to inhibit the inactivation of catalysts. This work provides deeply insights into the rational design of novel immobilized ILs catalysts for the benzene alkylation.

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure. Herein, we synthesized a series of novel Cu-based catalysts, Cu@NS-SiO₂ (NS = nano sphere) and alkali metals (Na, K, Rb, and Cs) doped Cu@NS-SiO₂, and applied them in hydrodeoxygenation reaction of anisole. High Cu dispersion was presented on all catalysts. The modification of alkali metals on Cu@NS-SiO₂ significantly enhanced the electron density of Cu sites in the following order: Cs > Rb > K > Na, among which Cs decreased the Cu 2p_3/2 binding energy most (by 0.7 eV). Moreover, the modification did not substantially affect the geometric structure of Cu species. This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole, and thus promoted the selectivity of benzene. Compared with Cu@NS-SiO₂ (∼59%), the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO₂ at ∼83%.

Electrochemical CO₂ reduction driven by renewable electricity is one of the promising strategies to store sustainable energy as fuels. However, the selectivity of value-added multi-carbon products remains poor for further application of this process. Here, we regulate CO adsorption by forming a Nafion layer on the copper (Cu) electrode that is repulsive to OH⁻, contributing to enhanced selectivity of CO₂ reduction to C₂₊ products with the suppression of C₁ products. The operando Raman spectroscopy indicates that the local OH⁻ would adsorb on part of active sites and decrease the adsorption of CO. Therefore, the electrode with repulsive to OH⁻ can adjust the concentration of OH⁻, leading to the increased adsorption of CO and enhanced C–C coupling. This work shows that electrode design could be an effective strategy for improving the selectivity of CO₂ reduction to multi-carbon products.

The coupling reaction of carbon dioxide (CO₂) and epoxides is one of the most efficient pathways to achieve the carbon balance. However, to accomplish it under the mild conditions, especially under the atmospheric pressure, is still a perplexing problem. Three novel ionic liquids (ILs), [DMAPBrPC][TMGH], [DMAPBrPC][DBUH], and [DMAPBrPC][BTMA], are designed and synthesized. All of them display the excellent catalytic activity for the title reaction achieving the yield over 96.6% under the atmospheric CO₂ pressure at 60 °C. Interestingly, [DMAPBrPC][BTMA] with the inert hydrogen atom in cation exhibits the superior catalytic activity as compared to other two ILs with the protic hydrogen atom in cation along with the same anion. The active hydrogen atom in [DMAPBrPC][TMGH] and [DMAPBrPC][DBUH] would impede the –COO⁻ group to absorb CO₂, which is an unfavorable item for the reaction. Moreover, the strong hydrogen bond in [DMAPBrPC][TMGH] and [DMAPBrPC][DBUH] would lessen the nucleophilic ability of Br⁻ anion resulting in the inferior catalytic performance, which is further confirmed by the density functional theory (DFT) calculations. The cation without the active hydrogen atom could also be employed to design the ILs with the excellent catalytic feature when it is combined with the suitable anion.

Dissolution of lithium cobalt oxide (LCO) is the key step for the recovery of valuable metals (e.g., Co and Li) from spent LCO-based lithium-ion batteries (LIBs). However, the dissolution process of LCO either needs toxic solvents, and high temperature, or shows low efficiency. Deep eutectic solvents (DESs) are potential green solvents to dissolve LCO. Here, DESs with polyethylene glycol (PEG) as hydrogen bond acceptor and ascorbic acid (AA) as hydrogen bond donor are found to dissolve LCO with 84.2% Co leaching efficiency at 80 ^oC and 72 h, which is higher than that from the reported references by common DESs. Furthermore, both DESs components (i.e., PEG and AA) are cheap, biodegradable, and biocompatible. AA could be easily and abundantly extracted from natural fruits or vegetables. It provides a new guide for the green, mild, and efficient dissolution of LCO aiming at sustainable recovery of spent LIBs.