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An eco-friendly and stable metal-free acidic catalyst phosphorus-doped graphitic carbon nitride (P–UCN) synthesized for the highly efficient dehydration of fructose to 5-Hydroxymethylfurfural (HMF) was presented. The acidic sites (P sites) were introduced into the g-C 3 N 4 structure via a simple thermal polycondensation of urea. A 91.7% HMF yield was achieved with optimal P–UCN catalyst under mild reaction conditions (160 °C, 3 h). XPS and NMR characterizations of P–UCN catalysts suggested that the P atoms may replace the corner and bay carbon sites, which could provide stable acidic sites for fructose dehydration into HMF. NH 3 -TPD analysis indicated that a moderate amount of P doped would provide higher catalytic activity for the dehydration reaction. Furthermore, the 1.0P–UCN (real content 1.83 wt %) catalyst was demonstrated high stability in the dehydration system and retained high reactivity after being recycled 5 times. The characterization results of recovered 1.0P–UCN further confirmed that the morphology and structure of the catalyst remained well after the dehydration reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

Cellulose-supported cobalt ferrite (CoFe 2 O 4 /RC) was synthesized via a facile one-pot hydrothermal method and demonstrated to be an efficient catalyst to activate peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX). The characterizations of CoFe 2 O 4 /RC catalysts revealed that an appropriate particle size of the cellulose support could promote the dispersion of CoFe 2 O 4 nanoparticles and consequently promote the catalytic activity of the resulting CoFe 2 O 4 /RC catalysts. The degradation of SMX reached 97.6 % within 20 min at 30 °C with the CoFe 2 O 4 /RC/PMS system. The mechanism of SMX degradation over CoFe 2 O 4 /RC-activated PMS was studied via EPR, XPS, and quenching tests. The results suggested that 1O 2 was the dominant reactive oxygen species and was accompanied by SO 4 −, OH, and O 2 − radicals for SMX degradation. The CoFe 2 O 4 /RC catalyst exhibited high stability and recyclability and maintained high catalytic activity after five experimental cycles. • NaOH acts as the additive to dissolute cellulose and the precipitant of CoFe 2 O 4. • Defibriled cellulose improved the dispersion of supported CoFe 2 O 4. • SMX degradation reached 97.6 % at optimized condition within 20 min. • Both free radical and non-radical processes were involved in the PMS activation. • 1O 2 was the dominating ROS responsible for the SMX degradation. [ABSTRACT FROM AUTHOR]

Gamma-valerolactone (GVL) is a versatile building block compound with wide applications and it can be obtained from biomass-derived chemical levulinic acid (LA). In this study, graphite carbon nitride (g-C 3 N 4) were prepared from two different precursors (urea and melamine) and used as the support to anchor ruthenium (Ru) nanoparticle (Ru/g-C 3 N 4) for catalytic transfer hydrogenation of LA to GVL. The resulting catalyst prepared from urea precursor (Ru/UCN) showed 100% LA conversion and nearly theoretic GVL yield of 99.8% under mild condition. Detailed characterizations of the Ru/g-C 3 N 4 suggested that Ru showed different interactions with the g-C 3 N 4 supports from two different precursors. Ru nanoparticles exhibited smaller size and better dispersion on the g-C 3 N 4 support from urea (UCN) than that from melamine (MCN). The XPS result indicated that more electron rich Ru0 species on the Ru/UCN catalyst also contributed to the higher catalytic activity of the Ru/UCN. Furthermore, the Ru/UCN catalyst was demonstrated high stability in acidic reaction medium and remained highly reactive after recycled for 5 times. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficient depolymerization of natural lignin is the key step to convert lignin to sustainable and added‐value chemicals. In this paper, a carbon‐supported Ni‐Cu bimetallic catalyst was developed for the hydrogenation of poplar lignin and β‐O‐4 model compounds. Five Ni‐Cu bimetallic catalysts were prepared by immobilizing Ni and Cu at fixed Ni loading (5%) and varied Cu loading (0%, 5%, 10%, 20%, 30%) on activated carbon (AC). All the Cu‐Ni/AC bimetal catalysts exhibited higher catalytic activity than either Ni/AC or Cu/AC catalysts. 5Ni‐5Cu/AC gave the highest bio‐oil yield of 40.2 wt% for the hydrogenation of. poplar lignin. The XPS, XRD, and HRTEM characterization of the catalysts showed that elemental copper and Cu‐Ni alloy were formed on the surface of 5Ni‐5Cu/AC catalyst, which could promote the efficient depolymerization of lignin into phenolic monomers. The possible mechanism for the lignin depolymerization was also studied and proposed based on the β‐O‐4 bond model compounds. This study provides a viable strategy for the conversion of lignin into added‐value chemicals with low cost catalyst. [ABSTRACT FROM AUTHOR]

Hydrodeoxygenation is one of the key steps to upgrade of biomass derived bio-oil into valuable biofuels and chemicals. Developing of highly reactive and cost-effective catalysts for bio-oil hydrodeoxygenation is highly desired. Layered Ni x Co y Al z catalyst was prepared using layered double hydroxide (LDH) as the precursors. The optimized Ni 1 Co 3 Al 2 -600 catalyst exhibits excellent catalytic performance for guaiacol hydrodeoxygenation. Guaiacol could completely converted with 90.0% of cyclohexanol selectivity under relatively mild reaction conditions. The XRD and HRTEM characterizations of the as prepared catalysts confirmed the formation of Ni-Co alloy and the XPS analysis revealed the strong interaction between Al species with both Ni and Co in catalyst Ni 1 Co 3 Al 2 -600, which should contribute to its high catalytic activity for guaiacol hydrodeoxygenation. Catalyst Ni 1 Co 3 Al 2 -600 also demonstrated excellent versatility for the hydrodeoxygenation reactions of guaiacyl and syringyl compounds as well as high stability. The results from this work could provide a new approach for the constructing of effective catalysts from non-noble metal LDHs. [Display omitted] • Guaiacol is converted to cyclohexanol over Ni 1 Co 3 Al 2 -600 catalysts. • Addition of Co to Ni 1 Al 2 -600 change the reaction path of guaiacol. • The synergy of the acid and metal sites increases the activity of the catalyst. • Methoxy ortho-substituted phenolic derivatives react more easily. [ABSTRACT FROM AUTHOR]

Glucose isomerization to fructose is a crucial step for the efficient production of fuel and valuable chemicals from renewable carbohydrates. Aluminum (Al) was introduced into the structure of a graphitic carbon nitride (g-C 3 N 4) by a simple thermal polycondensation of urea and aluminum chloride, and thereby, provided a series of Al-doped g-C 3 N 4 (x Al-UCN) catalysts for the isomerization reaction. A high fructose yield of 48.29%, comparable to the quantitative yields (ca. 50%) by enzymatic routes, was achieved with the 0.5Al–UCN catalyst. Detailed characterizations of a series of Al–UCN catalysts, with different Al loadings, showed that 1) the Al loading amount has a profound effect on the physical-chemical properties of Al–UCN catalysts; 2) excess Al loading can inhibit the formation of a crystalline g-C 3 N 4 structure; and 3) at lower Al loadings, the Al appears to be doped into the g-C 3 N 4 framework possibly via coordination bonds. The mechanism for glucose isomerization to fructose may involve both Lewis acid and base catalyzed routes, with the coordinated Al species (Al[6]) providing Lewis acidity, and N-containing groups on g-C 3 N 4 providing basicity. The additive effect of this dual-functionality is likely responsible for the high catalytic activity. The 0.5Al–UCN catalyst was readily recycled, demonstrating near-constant activity after 5 cycles of use. Altogether, glucose isomerization to fructose over the readily synthesized and recyclable Al–UCN catalyst could provide a highly-efficient and cost-effective step in lignocellulosic biomass valorization. [Display omitted] • Aluminum doped carbon nitride (Al–UCN) were prepared for glucose isomerization. • Al loading amount profoundly affected the properties of resulted Al–UCN catalyst. • 48.29% yield and 71.65% selectivity of fructose achieved over Al–UCN catalyst. • The reaction was conducted in green solvent GVL. • Coupled acid and base sites enhanced the isomerization activity of Al–UCN. [ABSTRACT FROM AUTHOR]

• Fe/Fe 3 C@C served both as the catalyst and microwave absorber for highly efficient methyl orange degradation. • The calcination temperature is a crucial factor determining the composition and microstructure of the Fe/Fe 3 C@C. • In situ generated free radicals over Fe/Fe 3 C@C is responsible for the degradation of methyl orange. Bifunctional catalyst Fe/Fe 3 C@C with magnetism was successfully prepared by sol-gel method and proved to degrade methyl orange with high efficiency under microwave irradiation. The Fe/Fe 3 C@C catalysts calcined at 500 °C, 600 °C, 700 °C were intensively characterized and compared in their crystalline structure, porosity, morphology and dielectric property. The results imply a phase and structure transformation in the materials as the calcination temperature increased. Fe/Fe 3 C@C-700 exhibited a core-shell structure and an apparent Fe 3 C phase. In addition, Fe/Fe 3 C@C-700 demonstrated excellent dielectric property as a microwave absorber than Fe/Fe 3 C@C-500 and Fe/Fe 3 C@C-600. At the same time, it gave a 100 % removal rate in 30 s for the degradation of methyl orange under microwave irradiation, outperformed the Fe/Fe 3 C@C-500 and Fe/Fe 3 C@C-600 and most other reported catalysts in similar studies. The possible mechanism of the methyl orange degradation should be ascribed to the in situ generation of •OH and O 2 •− active species over the Fe/Fe 3 C@C catalyst. The excellent microwave absorbing property of Fe/Fe 3 C@C-700 could also boost its catalytic activity and play a critical role during the super-fast microwave-assisted degradation process. The findings in this study could be informative for the development of a continuous process of dye wastewater treatment for industrial implementation. [ABSTRACT FROM AUTHOR]