Liquid Phase Esterification of Levulinic Acid into Ethyl Levulinate Over Sulphobenzylated Nanoporous Al-SBA-15 Catalyst

Value added chemicals, fuels, and fuel additives can be obtained from cheap bio masses such as levulinic acid. Levulinic acid is the dehydration and hydrolysis products of pentoses and hexoses. The present work deals with the synthesis of sulphobenzylated Al-SBA-15, [SO3H-Bz-Al-SBA-15], characterization by various analytical techniques such as XRD, BET, FT-IR, TGA, DTA, FE-SEM/EDS and HR-TEM/EDX techniques and evaluation of catalytic activity towards esterifi-cation of levulinic acid to ethyl levulinate under mild and non corrosive conditions. Sulphonation of the aromatic ring of the benzyl group has been done in different amounts to get nanoporous x% SO3H-Bz-Al-SBA-15 catalysts where (x ═ 0.02, 0.04, 0.06, 0.08 and 0.10% w/w). Among them 0.08% SO3H-Bz-Al-SBA-15 catalyst showed the highest conversion of levulinic acid (100%) with the highest selectivity towards ethyl levulinate (100%). Esterification of levulinic acid has been carried out with different primary alcohols and all of them yielded 100% selectivity towards alkyl levulinate. However conversion level of levulinic acid was found to be different with different alcohols. Reaction conditions have been optimized. The results were compared with other supported catalysts and discussed.

Kinetic Study Based on the Carbide Mechanism of a Co-Pt/γ-Al2O3 Fischer–Tropsch Catalyst Tested in a Laboratory-Scale Tubular Reactor

A Co-Pt/γ-Al2O3 catalyst was manufactured and tested for Fischer–Tropsch applications. Catalyst kinetic experiments were performed using a tubular fixed-bed reactor system. The operative conditions were varied between 478 and 503 K, 15 and 30 bar, H2/CO molar ratio 1.06 and 2.11 at a carbon monoxide conversion level of about 10%. Several kinetic models were derived, and a carbide mechanism model was chosen, taking into account an increasing value of termination energy for α-olefins with increasing carbon numbers. In order to assess catalyst suitability for the determination of reaction kinetics and comparability to similar Fischer–Tropsch Synthesis (FTS) applications, the catalyst was characterized with gas sorption analysis, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) techniques. The kinetic model developed is capable of describing the intrinsic behavior of the catalyst correctly. It accounts for the main deviations from the typical Anderson-Schulz-Flory distribution for Fischer–Tropsch products, with calculated activation energies and adsorption enthalpies in line with values available from the literature. The model suitably predicts the formation rates of methane and ethylene, as well as of the other α-olefins. Furthermore, it properly estimates high molecular weight n-paraffin formation up to carbon number C80.

Study of photovoltaic systems with differences connecting configuration topologies for applications in renewable energy systems

This paper focuses in the optimization of the efficiency of photovoltaic power conversion systems; we present a new alternative for improving both the optimization of the efficiency of photovoltaic power conversion chain. In this way, we present to the valuation problem of photovoltaic by new coupling systems between photovoltaic generators and their loads and performance of photovoltaic (PV) systems and the efficiency of the energy conversion by using different configuration of power converters. Different type’s improvements have been proposed of different architecture in order to choose the correct PV architecture for each PV installation on the efficiency improvement in all power conversion level stages between PV cells and loads. In this context, this work presents the study and adaptive simulation of photovoltaic systems with micro inverters configurations for applications of renewable energy. We performed comparative between a central and distribution connection of converter via an adaptation floor with Maximum Power Point Tracker (MPPT) control. For this reason, it is important to know different types of architecture and different configuration of power converters in order to choose the correct PV architecture for each PV installation. Simulation results are used to demonstrate the proposed topologies to provide improvement in efficiency over existing traditional PV systems.

Nickel-based perovskite catalysts: synthesis and catalytic tests in the production of syngas

La1-xSrxNiO3 (x= 0.0, 0.3 or 0.7) perovskite-type oxides were synthesized using the modified proteic gel method and using collagen as an organic precursor. Catalysts of La1-xSrxNiO3/Al2O3 were obtained using the wet impregnation method. The synthesized catalysts were characterized by X-ray diffraction, surface area and temperature-programmed reduction. The catalysts were evaluated in the partial oxidation reaction of methane, and the levels of selectivity to CO, CO2, H2 and H2O were determined. Among the catalysts studied, the catalyst LaNiO3/Al2O3 had the highest methane conversion level (78%) and higher H2 selectivity (55%).

Development of new catalytic processes for processing petroleum feedstock

Currently such factors as the use of heavier feedstocks, permanent strengthening of requirements to oil and gas product quality, introduction of technical regulations for oil products, which, in turn, necessitate the development of new technologies and catalysts, have a great influence on the global oil-refining and petrochemical industry development. Recently, a special attention is given to the development of new catalysts and processes for producing middle distillate fuels suitable for cold and arctic climatic conditions. Catalytic hydrodewaxing and isodewaxing processes are the most efficient in this field. Research into controlling a functional structure of catalysts and creation of catalytic systems based on zirconium dioxide modified by tungstate anions are of outstanding interest. The trend of the use of heavier petroleum feedstocks and the need to improve the oil conversion level demand will be based on destruction of high-molecular-weight compound structures with producing light and middle cuts. So, the most important processes for heavy oil residue conversion are those enabling to control transformations of resinous-asphaltenic materials by using nanoscale catalytic systems. One of the examples of the industrial implementation of technologies using suspended catalysts is the hydroconversion process implemented currently at AO TANECO (lisencer: TIPS RAS; general designer: OAO VNIPIneft).

Comparison study on pyrolysis characteristics and kinetics of corn stover and its digestate by TG-FTIR

The pyrolysis potential of corn stover digestate (CSD) was compared with corn stover (CS). The effects of anaerobic digestion (AD) on pyrolysis were investigated at different rates by a thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR). The distributed activation energy model (DAEM) was used to show the differences in the kinetics. The results indicated that the AD process improved the thermal stability with lower mean reactivity (RM), higher solid residue (S850), and decreased release of observed gaseous productions, except for CH4. The release of CH4 from CSD was higher than that of CS, especially in the temperature range of 430 °C to 520 °C. The activation energies (E) of CS and CSD were 184 kJ/mol to 293 kJ/mol (conversions were 0.1 to 0.8) and 99 kJ/mol to 331 kJ/mol (conversions were 0.1 to 0.9), respectively. The activation energies decreased after AD at the same conversion level. The calculated TG data of CS and CSD from the kinetic parameters were in good agreement with the experimental curves.

The Effect of KMnO4 Concentration on the Catalytic Activity of MnOx/Luffa Sponge Composites

MnOx/ luffa sponge composites were prepared by loading MnOx on/in porous luffa sponge under ambient conditions and an in-situ reduction method. We employed the oxidative decomposition of HCHO as probe reaction to investigate the effect of KMnO4 concentration on the catalytic activity of MnOx/ luffa sponge composites. It is shown that all the MnOx/ luffa sponge composites bear the activity for the catalytic decomposition of HCHO; the conversion of HCHO was found to be high at room temperature; the conversion level of HCHO was first increased and then decreased with the increase in the KMnO4 concentration. The HCHO conversion over the catalyst prepared from 10 g/L of KMnO4 solution was the largest among five catalysts.