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Transformation of levulinic acid (LA) to γ -valerolactone (GVL) via hydrogenation is a greener approach in synthesising the eco-friendly GVL fuel additive. In this work, highly active and stable pre-synthesized copper nanoparticles (CuNPs) are embedded and distributed into the ordered mesoporous carbon (OMC) support material by the chelate-assisted multicomponent assembly pathway method. The Cu/OMC nanocatalyst is characterized by different analytical instruments to determine the key properties. The ordered mesoporous carbon (OMC) structure was formed successfully by controlled synthesis steps via resol carbonization. The morphology and structure of OMC was confirmed by the XRD, TEM and HRTEM analysis. The OMC surface was functionalized with different oxygen-containing functional groups, which enhances the interactions with the Cu nanoparticles. The TEM micrographs reveal that Cu NPs with average size of ~5.5 nm was evenly distributed over the surface of the OMC matrix. The synthesized Cu/OMC catalyst showed remarkable activity and stability due to confinement effects of Cu in mesoporous carbon and the highly dispersed nanosized Cu particles, which are exposed sites over the support. More importantly, the stability of the Cu/OMC was excellent, and the activity did not decline even after 60 h time on stream test under optimized conditions (WHSV-2.28 h−1, 20 wt% aqueous LA, H2 flow- 30 mL/min, 260 °C at 0.1 MPa hydrogen pressure).

In this work, we designed versatile heterogeneous nanocatalysts based on palladium nanoparticles (PdNPs) decorated on metal oxides supports (i.e., PdNPs/γ-Al2O3, PdNPs/WO3 and PdNPs/Nb2O5) by step-wise controlled synthesis of novel monodispersed ∼2 nm PdNPs at room temperature and then impregnated over metal oxides. PdNPs supported catalysts were characterised by powder XRD, TEM, HRTEM, NH3-TPD, N2-BET, H2-TPR, and XPS techniques. PdNPs based catalysts studied in two different model reactions were presented i.e., biomass platform chemical intermediate γ-valerolactone (GVL) conversion into pentanoic acid (PA) studied in vapor phase hydrogenolysis and 4-Nitrophenol (4-NP) reduction to 4-Aminophenol (4-AP) in liquid phase using NaBH4 as reducing agent over 0.5 wt% Pd nanoparticles -based nanocatalysts. The relationship between the active sites and the catalytic performance was evaluated. The Under optimized reaction conditions, over 0.5 wt% PdNPs/γ-Al2O3 catalyst exhibited the highest PA yield of 100%, and over 0.5 wt% PdNPs/WO3, 0.5 wt% PdNPs/Nb2O5 exhibited PA yields of 98% and 96% respectively. Over PdNPs/γ-Al2O3, PdNPs/WO3, and PdNPs/Nb2O5, the reduction reaction rates in the 4-NP to 4-AP are 5.40 × 10−3 s−1, 2.55 × 10−3 s−1 and 2.30 × 10−3 s−1 respectively. The calculated thermodynamic parameters of the Ea values for 4-NP to 4-AP reaction were 25.30, 26.75, and 27.81 KJ/mol for the PdNPs/γ-Al2O3, PdNPs/WO3 and PdNPs/Nb2O5, respectively.

A direct alkaline hydrothermal method was used to synthesize mono- and bimetallic Ni and Cu on mesoporous silica (m-SiO2) as catalysts for the hydrogenation of furfural (FAL) to cyclopentanone (CPO). The catalysts were characterized by XRD, FTIR, H2-TPR, SEM, TEM, HR-TEM, XPS, ICP, BET, and CHN analysis. The results demonstrate that the addition of Cu metal improved the reducibility of Ni catalysts and revealed Ni-Cu alloy formation over m-SiO2. Furthermore, XPS and FTIR results reveal that the silanol groups on the catalyst surface play an important role in the ring rearrangement of furfuryl alcohol. Hence, the effect of silanol groups in the FOL rearrangement was studied in detail. Among the catalysts at fixed metal loading of 20 wt.%, Ni5Cu15/m-SiO2 catalyzed the formation of CPO as the main product due to the synergy of Ni-Cu alloy and surface silanol groups. Ni5Cu15 supported on a commercial mesoporous silica (Ni5Cu15/C-SiO2) showed inferior performance compared with the Ni5Cu15/m-SiO2 catalyst for the FAL hydrogenation. Reaction temperature and time were also optimized for the enhanced CPO yield over Ni5Cu15/m-SiO2. The Ni5Cu15/m-SiO2 catalyst is durable, as demonstrated by stability tests over multiple reuses. This effective and flexible NixCuy on m-SiO2 catalyst provides an effective candidate for efficient upgrading of furanics in selective hydrogenation reactions.

Conversion of biomass-derived furfural (FFA) platform molecule to value-added tetrahydrofurfuryl alcohol (THFA) molecule is a sustainable route using an efficient non-noble metallic catalyst in water solvent. In this work, Ni in various loadings on mesoporous titanium dioxide (m-TiO2) was synthesized in one pot by Evaporation-Induced Self-Assembly (EISA). The synthesised catalysts were evaluated for the hydrogenation of furfural to tetrahydrofurfuryl alcohol. The catalysts were characterised using a combination of spectroscopic techniques such as XRD, H2-TPR, H2-TPD, XPS, SEM-EDX, TEM, and HR-TEM. The characterization results show that the Ni/m-TiO2 materials exhibit enhanced electron-rich active sites, facilitated hydrogen spillover, uniform dispersion of small Ni particles (~5 nm), and strong metal support interaction between Ni and TiO2. Among the various Ni dopings, 7.5 wt.% Ni/m-TiO2 catalyst exhibited the best performance and achieved 99.9% FFA conversion and 93.2% THFA selectivity in water solvent at 100 °C and under 2 MPa H2. Additionally, detailed kinetic studies, process parameters, the stability and reusability of the catalyst were also studied. The results demonstrated that the 7.5 wt.% Ni/m-TiO2 catalyst is highly active and stable.

2-Methyltetrahydrofuran (MTHF) is a desirable biomass-based platform chemical with excellent potential as an ideal biofuel, green solvent, and raw material for synthesizing downstream chemicals. In this work, a series of copper nanoparticles encapsulated on SiO2 were prepared by the wet impregnation method and evaluated as efficient non-noble metal catalysts for the vapour-phase hydrogenation of γ-valerolactone (GVL) to MTHF in a fixed-bed reactor under mild reaction conditions. The obtained catalyst properties were determined by XRD, FE-SEM, TEM, UV-DRS, TPR, NH3-TPD, N2O decomposition and pore size distribution measurements. Meanwhile, the parameters/variables tuning their catalytic performance (activity, conversion, selectivity and stability) were examined. Various Cu loadings featured on the SiO2 support are essential for tuning the catalytic activity. Among the catalysts tested, a 5 wt% Cu/SiO2 catalyst showed a 97.2% MTHF selectivity with 71.9% GVL conversion, and showed a stability for 33 h time-on-stream, achieved at 260 °C and atmospheric pressure conditions. It was found that a huge dispersion of Cu metal in support, hydrogen activation ability, abundant acidic sites and surface area are all beneficial for improved MTHF selectivity.

Nickel modified strontium hydroxyapatite (Ni/Sr-HAP) supported catalysts are studied in selective methanation of CO/CO2. In this work, a new type of nano rod-shaped strontium hydroxyapatite-based catalysts with two different sizes and aspect ratios were prepared by sol–gel method and in next step, Ni precursor was wet impregnated i.e., denoted as Ni/Sr-HAP and Ni/Sr-HAP(F127). The catalytic tests were performed in CO and CO2 methanation reactions and evaluated the light-off temperatures curves (225–450 °C) under ambient pressure in a fixed-bed flow reactor. The physicochemical properties of the prepared catalysts were characterized by XRD, N2 physisorption, TEM, SEM, TPR, CO2/H2-TPD and H2-chemisorption techniques. From XRD analysis, both Ni/Sr-HAP and Ni/Sr-HAP(F127) were identified as the hydroxyapatite type structure with high crystallinity and very low intensity peaks corresponds to strontium phosphates as the main phase and structure. The TEM and SEM micrographs of Ni/Sr-HAP catalysts displayed a nano- rod shaped morphology with different dimensions and exhibited average Ni particle size of ~ 9.2 nm. While Ni/Sr-HAP(F127) shown the rod size in the length in the range of 100–250 nm and width in the range of 20–40 nm with average Ni particle size 5.7 nm. The F127 mediated support Sr-HAP synthesis i.e., Ni/Sr-HAP(F127) mesoporous catalyst possessed higher metal surface with smaller Ni particles size and possessed higher CO2 adsorption capacity. The medium strength basic sites of Ni/Sr-HAP catalyst played an important role in methanation reactions. Based on the characterization and the catalysts activity results, small sized nanorods of Ni/Sr-HAP(F127) is the most active and selective catalyst due to the higher Ni dispersion, higher amounts of medium basic sites, and reducibility character than the bigger nanorods based Ni/Sr-HAP catalyst. [ABSTRACT FROM AUTHOR]

Nickel modified strontium hydroxyapatite (Ni/Sr-HAP) supported catalysts are studied in selective methanation of CO/CO2. In this work, a new type of nano rod-shaped strontium hydroxyapatite-based catalysts with two different sizes and aspect ratios were prepared by sol–gel method and in next step, Ni precursor was wet impregnated i.e., denoted as Ni/Sr-HAP and Ni/Sr-HAP(F127). The catalytic tests were performed in CO and CO2 methanation reactions and evaluated the light-off temperatures curves (225–450 °C) under ambient pressure in a fixed-bed flow reactor. The physicochemical properties of the prepared catalysts were characterized by XRD, N2 physisorption, TEM, SEM, TPR, CO2/H2-TPD and H2-chemisorption techniques. From XRD analysis, both Ni/Sr-HAP and Ni/Sr-HAP(F127) were identified as the hydroxyapatite type structure with high crystallinity and very low intensity peaks corresponds to strontium phosphates as the main phase and structure. The TEM and SEM micrographs of Ni/Sr-HAP catalysts displayed a nano- rod shaped morphology with different dimensions and exhibited average Ni particle size of ~ 9.2 nm. While Ni/Sr-HAP(F127) shown the rod size in the length in the range of 100–250 nm and width in the range of 20–40 nm with average Ni particle size 5.7 nm. The F127 mediated support Sr-HAP synthesis i.e., Ni/Sr-HAP(F127) mesoporous catalyst possessed higher metal surface with smaller Ni particles size and possessed higher CO2 adsorption capacity. The medium strength basic sites of Ni/Sr-HAP catalyst played an important role in methanation reactions. Based on the characterization and the catalysts activity results, small sized nanorods of Ni/Sr-HAP(F127) is the most active and selective catalyst due to the higher Ni dispersion, higher amounts of medium basic sites, and reducibility character than the bigger nanorods based Ni/Sr-HAP catalyst. [ABSTRACT FROM AUTHOR]