Green Chemistry最新文献

Biomass provides a promising source of carbon for obtaining environment-friendly carbon materials, but obtaining heteroatom-doped carbon materials (HDCMs) from biomass directly by a green method still remains challenging. This study successfully synthesized nitrogen and phosphorus co-doped porous carbon materials (Y-NPC) by the simple in situ pyrolysis of renewable yeast mixed with water from 800 to 950 °C. Various characterization methods show that nitrogen and phosphorus are doped into the carbon skeleton and mainly exist in the forms of graphite-N, pyridine-N, C–P, P–N, and P–O states. The catalyst Y-NPC-900 °C with a 3D hierarchical porous structure and high P–N content exhibited superior nitro hydrogenation performance and reaction stability using molecular hydrogen and hydrazine hydrate as hydrogen sources under mild conditions. Density functional theory (DFT) calculations and experiments attributed the exceptional catalytic performance to hydrogen activation and the good adsorption ability of substrates over N, P co-doped carbon (NPC). Therefore, this research proposes an eco-friendly and simple synthesis strategy for in situ N, P co-doping metal-free carbon catalysts derived from biomass, showing the significance of N, P co-doping and single N- or P-monodoping in the charge distribution of carbon materials.

2,5-Furandicarboxylic acid (FDCA) is one of the most promising biodegradable substitutes for fossil-derived terephthalic acid (PTA) and adipic acid. The production of FDCA from biomass-derived 5-hydroxymethylfurfural (HMF) is significant and has attracted great attention. However, the major challenge lies in the development of a non-precious metal-based catalyst system without employing a homogeneous base. Herein, we successfully prepared an atomically dispersed Fe–N–C/γ-Al₂O₃ catalyst, which affords superior catalytic performance in terms of activity and stability with a FDCA yield of 99.8% and reusability of five recycle times in the catalytic oxidation of HMF to FDCA under base-free mild conditions. Based on controlled experiments and complementary characterization studies, we found that the atomically dispersed medium-spin Fe–N₅ active sites together with the surface acidic/basic sites of alumina synergistically enhanced the catalytic activity and selectivity towards FDCA under base-free conditions. Our process eliminates the employment of expensive oxidants and corrosive bases, leading to economic and green biomass transformations.

N-Nitrosamines represent a class of bifunctional nitrogen-radical precursors, but their application potential remains largely unexplored. This study reports the highly atom-economical production of diverse α-oximino sulfonamides via direct photo-mediated radical relay oximinosulfonamidation of activated or unactivated alkenes with N-nitrosamines triggered by organic sulfide. N-Nitrosamines worked as bifunctional reagents in this transformation, simultaneously generating aminyl radicals and NO radicals. The organic sulfide was designed to act as a radical decaging agent as well as a source of sulfonyl. Its strong radical capturing ability and affinity for alkenes enable the rapid capturing of the aminyl radicals, thereby inhibiting the rapid recombination of radical pairs in the solvent cage. The synthesized oxime units could also be easily converted into other functional groups, leading to selective downstream transformations. The mild photodegradation reaction of harmful N-nitrosoamines showed high functional group tolerance and compatibility, facilitating the late-stage functionalization of natural products and drug molecules, expanding the biologically relevant chemical space.

A simple and recyclable homogeneous catalytic system for the hydrogenation of carbon monoxide to methanol was established. The reaction is catalyzed by a molecular manganese complex using a high-boiling alcohol as the solvent for catalyst immobilization. The CO hydrogenation is assisted by the product itself and the solvent through the formation of a methyl or dodecyl formate ester intermediate mediated by catalytic amounts of NaOMe as the base. This allows the catalytic formation of methanol in alcohols combined with facile product separation and catalyst recycling via distillation. Initial turnover frequencies (TOF) of 2250 h⁻¹ were reached under optimized conditions in 1-dodecanol/methanol as the reaction medium (T = 160 °C, p(H₂/CO) = 80/10 bar). The performance was stabilized in batch-wise recycling over 6 runs achieving a total turnover number (TTON) of >12 000 corresponding to an enhancement of more than five times compared to single batch operation under identical conditions. Minimal leaching of the components of the organometallic catalyst was observed during distillative product separation and catalyst activity could be fully restored by re-addition of the base NaOMe.

The development of electrocatalysts that convert CO₂ and N₂ in flue gas to directly usable urea does not only explore the hidden value of exhaust gas but also alleviates the global environmental issues caused by excessive CO₂ emissions; yet, related research studies are still in their infancy. Herein, multi-porous Cu–W₁₈O₄₉@ZIF-8, composed of ultra-small nanosized ZIF-8 on Cu-doped W₁₈O₄₉ nanowires, was fabricated as a urea-generation electrocatalyst in flue gas. It exhibits an appealing Faraday efficiency of urea up to 16.1% at −0.9 V (vs. RHE) and an outstanding yield of 1.33 mmol g⁻¹ h⁻¹ at −1.0 V (vs. RHE) under the flue gas atmosphere. The catalytic performance was maintained for a wide range of N₂ : CO₂ ratios. Theoretical calculations indicate that the doped copper regulates the electron density around the adjacent W–W, which facilitates N₂ adsorption, partly suppresses the HER side reaction, and decreases the ΔG of the following multi-step hydrogenation after *CO insertion until urea production.