2,5-Dimethylfuran Production by Catalytic Hydrogenation of 5-Hydroxymethylfurfural Using Ni Supported on Al2O3-TiO2-ZrO2 Prepared by Sol-Gel Method: The Effect of Hydrogen Donors.

5-Hydroxymethylfurfural (5-HMF) has been described as one of the 12 key platform molecules derived from biomass by the US Department of Energy, and its hydrogenation reaction produces versatile liquid biofuels such as 2,5-dimethylfuran (2,5-DMF). Catalytic hydrogenation from 5-HMF to 2,5-DMF was thoroughly studied on the metal nickel catalysts supported on Al2O3-TiO2-ZrO2 (Ni/ATZ) mixed oxides using isopropanol and formic acid (FA) as hydrogen donors to find the best conditions of the reaction and hydrogen donor. The influence of metal content (wt%), Ni particle size (nm), Nickel Ni0, Ni0/NiO and NiO species, metal active sites and acid-based sites on the catalyst surface, and the effect of the hydrogen donor (isopropanol and formic acid) were systematically studied. The structural characteristics of the materials were studied using different physicochemical methods, including N2 physisorption, XRD, Raman, DRS UV-Vis, FT-IR, SEM, FT-IR Pyad, H2-TPD, CO2-TPD, H2-TPR, TEM and XPS. Second-generation 2,5-DMF biofuel and 5-HMF conversion by-products were analyzed and elucidated using 1H NMR. It was found that the Ni0NiO/ATZ3WI catalyst synthesized by the impregnation method (WI) generated a good synergistic effect between the species, showing the best catalytic hydrogenation of 5-HMF to 2,5-DMF using formic acid as a hydrogen donor for 24 h of reaction and temperature of 210 °C with 20 bar pressure of Argon (Ar).

γ-Valerolactone Production from Levulinic Acid Hydrogenation Using Ni Supported Nanoparticles: Influence of Tungsten Loading and pH of Synthesis.

γ-Valerolactone (GVL) has been considered an alternative as biofuel in the production of carbon-based chemicals; however, the use of noble metals and corrosive solvents has been a problem. In this work, Ni supported nanocatalysts were prepared to produce γ-Valerolactone from levulinic acid using methanol as solvent at a temperature of 170 °C utilizing 4 MPa of H2. Supports were modified at pH 3 using acetic acid (CH3COOH) and pH 9 using ammonium hydroxide (NH4OH) with different tungsten (W) loadings (1%, 3%, and 5%) by the Sol-gel method. Ni was deposited by the suspension impregnation method. The catalysts were characterized by various techniques including XRD, N2 physisorption, UV-Vis, SEM, TEM, XPS, H2-TPR, and Pyridine FTIR. Based on the study of acidity and activity relation, Ni dispersion due to the Lewis acid sites contributed by W at pH 9, producing nanoparticles smaller than 10 nm of Ni, and could be responsible for the high esterification activity of levulinic acid (LA) to Methyl levulinate being more selective to catalytic hydrogenation. Products and by-products were analyzed by 1H NMR. Optimum catalytic activity was obtained with 5% W at pH 9, with 80% yield after 24 h of reaction. The higher catalytic activity was attributed to the particle size and the amount of Lewis acid sites generated by modifying the pH of synthesis and the amount of W in the support due to the spillover effect.

Chemical and Structural Changes by Gold Addition Using Recharge Method in NiW/Al2O3-CeO2-TiO2 Nanomaterials.

NiWAu trimetallic nanoparticles (NPs) on the surface of support Al2O3-CeO2-TiO2 were synthesized by a three-step synthetic method in which Au NPs were incorporated into presynthesized NiW/Al2O3-CeO2-TiO2. The recharge method, also known as the redox method, was used to add 2.5 wt% gold. The Al2O3-CeO2-TiO2 support was made by a sol-gel method with two different compositions, and then two metals were simultaneously loaded (5 wt% nickel and 2.5 wt% tungsten) by two different methods, incipient wet impregnation and ultrasound impregnation method. In this paper, we study the effect of Au addition using the recharge method on NiW nanomaterials supported on mixed oxides on the physicochemical properties of synthesized nanomaterials. The prepared nanomaterials were characterized by scanning electron microscopy, BET specific surface area, X-ray diffraction, diffuse reflectance spectroscopy in the UV-visible range and temperature-programmed desorption of hydrogen. The experimental results showed that after loading of gold, the dispersion was higher (46% and 50%) with the trimetallic nanomaterials synthesized by incipient wet impregnation plus recharge method than with impregnation plus ultrasound recharge method, indicating a greater number of active trimetallic (NiWAu) sites in these materials. Small-sized Au from NiWAu/ACTU1 trimetallic nanostructures was enlarged for NiWAu/ACT1. The strong metal NPs-support interaction shown for the formation of NiAl2O4, Ni-W-O and Ni-Au-O species simultaneously present in the surface of trimetallic nanomaterial probably plays an important role in the degree of dispersion of the gold active phase.

Photodegradation of 17 α-methyltestosterone using TiO2 -Gd3+ and TiO2-Sm3+ photocatalysts and simulated solar radiation as an activation source.

According to the search in the state of the art, no antecedents were found in which photocatalytic degradation of 17α-methyltestosterone (MT) hormone has been carried out using doped-TiO2. Nor have the transformation products formed during the heterogeneous photocatalysis (FH) been identified. Therefore, in this study we analyzed the photocatalytic degradation of the MT in aqueous solution, using doped TiO2 with Sm3+ or Gd3+ at 0.3 and 0.5 %wt. Thermal treatment temperature (500 °C and 800 °C) and MT (20 mgL-1) mineralization were also studied. All photocatalysts were synthesized using the sol-gel method and characterized by X-ray Diffraction (XRD), Specific Surface Area (BET), Ultraviolet-visible Spectroscopy (UV-vis), High-Resolution Transmission Electron Microscope/Energy-Dispersive X-ray analysis (HRTEM/EDS) and, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). MT mineralization was followed by a total organic carbon analyzer (TOC). The route of the photocatalytic mineralization of the hormone was obtained from the analysis of intermediate compounds determined by high performance liquid chromatography coupled to mass spectrometry (LC-TOF-MS). The results showed that TM and its transformation products were not degraded by photolysis. However, the degree of mineralization of the hormone was greater when the photocatalytic process was used. The photocatalytic efficiency was related to the dopant concentration, dopant type and thermal treatment. Therefore, Sm (0.3%)/TiO2 calcined at 500 °C showed the best performance for photocatalytic mineralization of MT.

Effect of the CuAl2O4 and CuAlO2 Phases in Catalytic Wet Air Oxidation of ETBE and TAME using CuO/γ-Al2O3 catalysts.

This paper studies Cu/Al2O3 catalysts, synthesized in two ways: copper deposit in the synthesis of alumina (sol gel) and incipient impregnation stabilized at 400 °C. The materials were characterized by X-ray diffraction studies, nitrogen physisorption, temperature programmed reduction of H2, dehydration of isopropanol, scanning electronic microscopy, transmission electronic microscopy, which were evaluated in the liquid phase oxidation reaction of ethyl tert-butyl ether and tert-amyl methyl ether. The formation of CuAl2O4 and CuAlO2 in the samples synthesized by sol gel, led to a modification of the texture, thus resulting in an expansion of the specific area of the materials. CuAl2O4 and CuAlO2 have been identified by DRX from a content of 10 % Copper, the first showed the highest intensity with this technique. In the same way, these species favor the presence of Lewis acid sites; this is reflected in the materials with (Di-isopropyl Ether) DIPE of 96.7 % and 91.1 % for the samples SAlCu5 and SAlCu15 respectively. The catalytic activity of the materials prepared by sol gel is in the function of the number of surface acid sites, the smaller particle size of the Cu and the surface of the contact, in the case of the ETBE meanwhile for TAME the activity was based mainly on the strength of the present acid sites. With impregnated materials, the activity is attributed to the smaller particle size of the Cu and the greater strength of the surface acid sites in the solid. The formation of spinel species inhibits the leaching phenomenon in the reaction milieu.

Effect of gold addition by the recharge method on silver supported catalysts in the catalytic wet air oxidation (CWAO) of phenol.

Catalysts Ag/ZrO2-CeO2 and Au/ZrO2-CeO2 were synthesized by a deposition-precipitation method and Ag-Au/ZrO2-CeO2 was prepared using a recharge method for the second metal (Au). The materials were characterized by physisorption of N2, XRD, ICP, UV-vis RDS, H2-TPR, XPS and TEM. The results obtained show that the specific areas for monometallic materials were 29-37 m2 g-1 and 27-74 m2 g-1 for bimetallics. The tetragonal crystal phase of ZrO2 stabilizes when CeO2 quantity increases. Using XPS an increment in Ce3+ species abundance was determined for bimetallic catalysts in contrast to the monometallic ones; according to the Ag 3d region, this metal oxidation was observed when augmenting the content of CeO2 in the materials, and with Au the opposite effect was produced. It was determined by TEM, that the average size of the metallic particles was smaller at bimetallic catalysts due the preparation method. Catalytic activity was evaluated by CWAO of phenol, the Ag-Au/ZrO2-CeO2 catalyst with 20% wt of cerium reached a degradation of 100% within an hour, being the most active catalyst. Maleic, formic and oxalic acid were identified as reaction intermediates; and at the end of the reaction acetic acid was identified as the main by-product, because it is the most refractory and the conditions for oxidation must be more severe.

Treatment of phenol by catalytic wet air oxidation: a comparative study of copper and nickel supported on γ-alumina, ceria and γ-alumina-ceria.

Cu, Ni, CuO and NiO catalysts, prepared by wet impregnation with urea and supported on γ-Al2O3, CeO2, and Al2O3-CeO2, were evaluated for Catalytic Wet Air Oxidation (CWAO) of phenol in a batch reactor under a milder condition (120 °C and 10 bar O2). The synthesized samples, at their calcined and/or their reduced form, were characterized by XRD, H2-TPR, N2 adsorption-desorption, SEM-EDS and DR-UV-Vis to explain the differences observed in their catalytic activity towards the studied reaction. The influence of the support on the efficiency of CWAO of phenol at 120 °C and 10 bar of pure oxygen has been examined and compared over nickel and copper species. The SEM-EDS results reveal that the spherical crystalline Cu and Ni were successfully deposited on the surface of γ-Al2O3, CeO2, Al2O3-CeO2 within 16-90 nm and that they were highly homogeneously dispersed. It was found that catalysts prepared from impregnation solutions of Cu(NO3)2·3H2O and Ni(NO3)2·6H2O with urea addition had different textural characteristics and degrees of dispersion of Cu and Ni species. The urea addition in the traditional wet impregnation method was essential to improve the reducibility and degree of dispersion in Ni, and to a lesser extent, in Cu. According to the characterization analysis of H2-TPR and UV-VIS RD a structure-activity relationship can be determined. The chemical oxygen demand (COD) and GC analyses confirmed the effect of calcined and reduced species for Cu and Ni applied to the catalytic oxidation of phenol, showing their significant impact in the final performance of the catalyst.