RSC sustainability最新文献

Fumarate, an unsaturated dicarboxylic acid, is an important material for producing unsaturated polyester resins and biodegradable plastics. Fumarate synthesis from petroleum-derived benzene and butane as starting materials is expected to be replaced by synthesis methods from renewable raw materials. In this work, fumarate synthesis from gaseous CO₂ and pyruvate in an aqueous medium using a multi-biocatalytic system consisting of pyruvate carboxylase (PC), malate dehydrogenase (MDH) and fumarase (FUM) in the presence of ATP and NADH is accomplished. The conversion yield of fumarate from pyruvate using this system was estimated to be approximately 16% after 5 h of incubation.

Doubly decarboxylative coupling between two different carboxylic acids to form a new C–C bond is a powerful tool for the rapid assembly of complex compounds. Herein, we report a metal-free three-component decarboxylative strategy for the construction of diverse propargylamines in good yields with high chemoselectivity. This operationally simple method can be applied to various amino acids, α-keto acids, and terminal alkynes, providing a powerful new protocol for propargylamine synthesis. The reaction without the addition of metal catalysts has the advantages of broad scope and functional group compatibility, and environmental friendliness.

The selective hydrodeoxygenation of lignin derived aromatics represents an important step towards the valorization of biomass. With this goal in mind, we synthesized a hybrid molecular/heterogeneous catalyst comprised of a (2,6-bis(1-methylbenzimidazolyl)pyridine-4′-aminopropyltrisiloxane)palladium(II) molecular catalyst covalently bound to a solid silica support through the siloxane functional group. A series of model complexes containing C–O bonds typically found in lignin biomass were explored and varying degrees of C–O bond hydrogenation were achieved. The stable covalent binding of the catalyst to the support was attributed to the observed long catalyst lifetimes which led to over 6000 catalytic turnovers without catalyst deactivation. Spectroscopic characterization of the catalyst pre- and post-catalytic reactions shows the catalyst maintains molecular integrity under the reaction conditions examined. The catalyst also exhibited complete selectivity for hydrodeoxygenation over ring hydrogenation of oxygenated aromatic molecules.

Carbanogels are carbon nanotube (CNT) lattices formed by carbon capture and utilization molten carbonate electrolysis of CO₂. Higher tensile strength polymer composites with these CNTs from CO₂ are prepared with epoxies and thermoplastics. The composites use less polymer to achieve strength, thereby lowering the polymer's carbon footprint.

An unprecedented amidation of oxidized carbon black (oCB) by a mechanochemical approach is reported. The reaction proceeds in the presence of octadecylamine (ODA) in a short time, providing the corresponding adduct (oCB/ODA) with a high degree of functionalization. Hummers and ball milling procedures were used to obtain oxidized carbon black in solution and solvent-free conditions, respectively. Although the oxidation procedure used for oCB synthesis can deeply affect the degree of amidation because of the different nature of the functional groups on the carbon surface, the resulting powders were both functionalized with amine. The corresponding adducts showed a strong inversion of polarity, going from the high dispersibility in the water solution of the starting material to the high hydrophobic behaviour due to the alkyl chains bonded on the surface. Since the mechanochemical approach respects important green metrics, the procedure is highly sustainable.

Correction for ‘Cleaning steel by devulcanizing rubber from used automotive tires' by Yang Chen et al., RSC Sustain., 2023, 1, 2006–2013, https://doi.org/10.1039/D3SU00218G.

Photocatalytic production of CO from CO₂ has the potential for safe and atom-economic production of feedstock chemicals via in situ carbonylation chemistry. We developed novel ionic liquid-based polymeric materials through radical copolymerisation of 1-butyl-3-vinylimidazolium chloride and photocatalytically active Re- and Ru-complexes that serve as the CO₂ reduction catalyst and photosensitiser, respectively. The crosslinked polymeric framework allows for the facile immobilisation of molecular organometallic complexes for use as heterogenised catalysts; moreover, the involved imidazolium core units co-catalyze the reduction of CO₂via covalent interaction. The ratio of sensitiser and catalyst was analysed by laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) and set in relation to results from photocatalytic experiments. Ultimately, the heterogenous polymeric framework showed high selectivity for CO formation on photocatalytic CO₂ reduction with improved stability to the corresponding homogenous system.

This work utilizes an innovative microwave-visible irradiated continuous stirred slurry reactor (MWVIS-CSSR) for sustainable continuous production of a drop-in biofuel, namely, ethyl levulinate (EL), from pretreated sugarcane bagasse (PSCB). Besides, a novel realistic kinetic model, considering MWVIS intensified EL production through parallel non-catalytic and homogeneous–heterogeneous catalytic pathways in the presence of a magnetic Ni_0.5Zn_0.5Fe₂O₄ (NZF) photocatalyst in conjunction with an oxalic acid–choline chloride based acidic deep eutectic solvent (DES2), was also formulated and validated (R² adj. ≥ 0.95). The 5 liter volume MWVIS-CSSR could render maximum 54.7 mol% EL yield (selectivity: 97.85%) at a feed flow rate of 35 ml min⁻¹ under optimized conditions (temperature: 100 °C, NZF loading: 6 wt% PSCB, stirring speed: 500 rpm). Remarkably, the synergistic impact of MW and VIS irradiation substantially elevated the EL yield (54.7 mol%) compared to those of the individual MW (29.45 mol%) and VIS (20.1 mol%) systems. The optimally produced EL when blended at 5 vol% with B10 and B20 (10% and 20% biodiesel–diesel blends) could enhance the brake thermal efficiency (1–2%) besides mitigating 21–22% HC and 7.5–20% CO engine exhaust emissions in comparison with reference blends (B10 and B20). Notably, the reactor scale-up study based on the penetration depth of the MW and VIS energy of NZF and DES2 showcased the potential to upscale the 5 liter MWVIS-CSSR to a 1 m³ volume, allowing EL production to reach 689 kg h⁻¹ with a sugarcane bagasse processing capacity of 2000 kg h⁻¹. Moreover, the process simulation conducted in Aspen Plus software, utilizing COSMO-based property estimation with DFT calculations, alongside the techno-economic analysis, revealed a robust internal rate of return (IRR) of 54.25% and a net present value (NPV) of 8.22 × 10⁵ US$ with a payback period of 4.91 years. Additionally, the environmental impact analysis study for the scaled-up EL production process in the MWVIS-CSSR revealed a reduction of 40–60% in marine ecotoxicity and 39–61% in human toxicity compared to the separate MW-CSSR and VIS-CSSR systems.

During the energy transition, the demand for strategic metals has become a focal point due to their crucial roles in advancing cleaner energy technologies and sustainable practices. As a response to the potential supply vulnerabilities of critical raw materials, recycling has gained attention, despite some methods being more expensive than traditional mining. In this context, new technologies based on microwave radiation have been recently introduced to recover lithium from spent lithium-ion batteries. This study highlights the innovative results achieved through the application of microwave heating to lithium cobalt oxide (LCO) black mass, showing that mass increase can support the possibility of proposing the technology as a new sustainable approach. The possibility of coupling carbon materials with magnetic materials, available in the black mass (BM) results in a strategic approach to increasing the final temperature of microwave-absorbing materials. The process proves highly efficient in lithium recovery, with a treatment at 600 W for 5 minutes, reaching a value higher than 80%, while also eliminating some labour-intensive pre-treatment steps. The research sheds light on both the advantages and potential challenges associated with this ground-breaking technology.

Ricinoleic acid, a natural hydroxy fatty acid, is a good candidate for preparing biodegradable polymer elastomers. Herein, high molecular weight poly(ricinoleic acid) (PRA) with a weight average molecular weight up to 122 kDa was successfully synthesized by solution polycondensation of methyl ricinoleate (MR) in hydrophobic ionic liquids, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The influence of monomer concentration, polymerization temperature and time, catalyst and properties of the ionic liquids on the polycondensation was comprehensively studied. Compared with the melt polycondensation, the solution polycondensation of MR in the ionic liquids can achieve much higher molecular weights. The PRA polymerized in ionic liquids shows a 100% cis structure like the natural monomer.