Efficient Preparation of Liquid Fuel 2,5-Dimethylfuran from Biomass-Derived 5‑Hydroxymethylfurfural over Ru–NaY Catalyst

An efficient catalytic process for the selective conversion of biomass-derived 5-hydroxymethylfurfural (HMF) to high quality liquid fuel 2,5-dimethylfuran (DMF) was achieved over Ru nanoparticles dispersed on NaY zeolite. The structural and morphological features of the catalysts were studied by using various physicochemical characterization techniques. HMF conversion of 100 mol % with 78 mol % DMF yield was achieved using 2 wt %Ru–NaY catalyst in a short duration of the reaction. This catalyst displayed excellent recyclability without any loss in activity when it was used for five times. The study clearly showed that well-dispersed Ru nanoparticles are highly active and selective for the conversion of HMF to DMF. The reaction pathway for the conversion of HMF to DMF was explored by monitoring the reaction intermediates at different stages and intervals of the reaction

Non-phosgene route for the synthesis of methyl phenyl carbamate using ordered AISBA-15 catalyst

Methyl phenyl carbamate (MPC) has been synthesized under liquid phase conditions from dimethyl carbonate and aniline by using mesoporous AlSBA-15 catalyst. The catalyst with different Si/Al ratio was synthesized by isomorphous substitution of aluminium into the framework of siliceous SBA-15. The structural integrity of the catalyst system was diagnosed with the help of various characterization techniques such as X-ray diffraction, surface analysis, and the acidity measurement has been done by TPD using ammonia as probe molecule. AlSBA-15 (Si/Al = 10) exhibited highest catalytic activity in the synthesis of MPC under the reaction conditions studied. The effect of parameters such as molar ratio of reactants, catalyst concentration, reaction temperature and time on the conversion of aniline was investigated. The results demonstrated that an aniline conversion of 99% and MPC selectivity of 71% were achieved when the reaction was carried out at 100 °C, DMC to aniline mole ratio of 10 with 5% of catalyst (wt% of total reaction mixture) for 3 h

Critical Surface Parameters for the Oxidative Coupling of Methane over the Mn–Na–W/SiO₂ Catalyst

The work here presents a thorough evaluation of the effect of Mn–Na–W/SiO₂ catalyst surface parameters on its performance in the oxidative coupling of methane (OCM). To do so, we used microporous dealuminated β-zeolite (Zeo), or mesoporous SBA-15 (SBA), or macroporous fumed silica (Fum) as precursors for catalyst preparation, together with Mn nitrate, Mn acetate and Na₂WO₄. Characterizing the catalysts by inductively coupled plasma–optical emission spectroscopy, N₂ physisorption, X-ray diffraction, high-resolution scanning electron microscopy–energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and catalytic testing enabled us to identify critical surface parameters that govern the activity and C₂ selectivity of the Mn–Na–W/SiO₂ catalyst. Although the current paradigm views the phase transition of silica to α-cristobalite as the critical step in obtaining dispersed and stable metal sites, we show that the choice of precursors is equally or even more important with respect to tailoring the right surface properties. Specifically, the SBA-based catalyst, characterized by relatively closed surface porosity, demonstrated low activity and low C₂ selectivity. By contrast, for the same composition, the Zeo-based catalyst showed an open surface pore structure, which translated up to fourfold higher activity and enhanced selectivity. By varying the overall composition of the Zeo catalysts, we show that reducing the overall W concentration reduces the size of the Na₂WO₄ species and increases the catalytic activity linearly as much as fivefold higher than the SBA catalyst. This linear dependence correlates well to the number of interfaces between the Na₂WO₄ and Mn₂O₃ species. Our results combined with prior studies lead us to single out the interface between Na₂WO₄ and Mn₂O₃ as the most probable active site for OCM using this catalyst. Synergistic interactions between the various precursors used and the phase transition are discussed in detail, and the conclusions are correlated to surface properties and catalysis