Selective biomass conversion over novel designed tandem catalyst

Selective conversion of biomass into targeted molecules like polyols, especially, from cellulosic compounds, is being widely investigated as a sustainable process to produce biodiesel and bio- additives. The known process involves two steps, namely hydrolysis and hydrogenation. Thus, it requires two different catalytic materials or bifunctional catalysts. In this context, the present work reports a new catalytic approach based on the use of tandem catalysts, consisting of the combination of an acid solid catalyst (active for hydrolysis) and a supported metal catalyst (active for hydrogenation). Two different functionalized activated carbons and the resin Amberlyst 15 have been tested as solid acid catalysts, and Ru nanoparticles supported on the original activated carbon (SA) are the metal catalyst part of the tandem. All the tested tandem catalysts exhibited higher activity than the supported Ru catalyst did. The highest cellulose conversion and selectivity to sorbitol (70% and 86%, respectively) have been obtained over a novel tandem catalyst, which resulted from a physical mixture between a sulfuric acid modified SA carbon (SASu) and Ru loaded SA (Ru/SA), leading to a tandem catalyst (Ru/SA + SASu). This novel-designed tandem catalyst is reusable. Based on tandem catalysts with a solid-solid system combination, the adopted novel- designed catalytic approach is cost-efficient and sustainable, and can be considered promising for the green production of high-added-value chemicals.

Experimental study and numerical modeling of the thermal behavior of an industrial prototype ceramic furnace:Energy and environmental optimization

This article focuses on the experimental and numerical study of an industrial prototype furnace intended for the production of ceramics in order to improve the energy efficiency and therefore optimize the fuel consumption and the corresponding carbon dioxide emissions.In order to understand the thermal behavior from which stems the energy efficiency of the experimental prototype,we establish in this work,a simplified modeling allowing to establish a mathematical model describing the thermal behavior of the furnace.The model is able to accurately predict the spatial and temporal distribution of the temperature at each point of the furnace to control the firing of the refractory product so that the final product is of good quality in terms of resistance and hardness.In addition,the power consumed by the prototype must be optimized in order to reduce energy and environmental consumption.In particular,this efficient technology has allowed us to save 83% of energy used in the traditional furnace and to reduce 87.36% of the relative carbon dioxide emission.The simulation of the mathematical model made it possible to compare the numerical results with the experimental measurements obtained by the prototype as well as to validate the model and to adjust the heat transfer parameters.

Fe-Promoted Copper Oxide Thin-Film Catalysts for the Catalytic Reduction of N_(2)O in the Presence of Methane

Thin-film catalysts are recently recognized as promising catalysts due to their reduced amount of materials and good catalytic activity,leading to low-cost and high-efficiency catalysts.A series of CuFeO_(x)thin-film catalysts were prepared with different Fe contents using a one-step method as well as tested for the catalytic reduction of nitrous oxide(N_(2)O)in the presence of CH_(4)at a high GH SV of 185000 mL/(g·h).The increase of iron strongly affects the dispersion and leads to the creation of a less-active segregated Fe_(2)O_(3)phase,which was confirmed by XRD,EDX,and XPS outcomes.The results show that the synergistic properties between Cu and Fe,which affect the CuFeOxfilm catalysts in many aspects,such as the hollow-like texture,specific surface area,nano-crystallite size,the surface contents of Cu^(+),Fe^(3+),and oxygen species,the reductive strength and the strong active sites on the surface.Using DFT calculations,the adsorption and decomposition energy profiles of N_(2)O on the CuFeO_(2)(012)surface model were explored.The surface Fe-site and hollow-site are active for N_(2)O decomposition,and the decomposition energy barriers on the Fe-site and the hollow-site are 1.02 eV and 1.25 eV respectively at 0 K.The strategy adopted here to tailor the activity through low-doping Fe-oxide catalysts could establish a promising way to improve the catalytic reduction of N_(2)O with CH_(4).