scholarly journals Use of Co/Fe-Mixed Oxides as Heterogeneous Catalysts in Obtaining Biodiesel

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 403 ◽  
Author(s):  
Norma Gutiérrez-Ortega ◽  
Esthela Ramos-Ramírez ◽  
Alma Serafín-Muñoz ◽  
Adrián Zamorategui-Molina ◽  
Jesús Monjaraz-Vallejo
Keyword(s):  
Fourier Transform ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Mixed Oxides ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Catalyst Composition ◽  
Catalyst Type ◽  
Diffuse Reflectance Infrared

Catalyst-type mixed metal oxides with different compositions and Co/Fe ratios were obtained from layered double hydroxides to be used as heterogeneous catalysts in the production of biodiesel. The effect of the Co/Fe ratio on the precursors of the catalysts was analyzed, considering their thermal, textural and structural properties. The physicochemical properties of the catalysts were determined by thermogravimetric analysis (differential scanning calorimetry and thermogravimetric), X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy and N2-physisorption. The conversion to biodiesel using the different catalysts obtained was determined by diffuse reflectance infrared Fourier-transform spectroscopy and 1H-Nuclear magnetic resonance spectroscopy, allowing us to correlate the effect of the catalyst composition with the catalytic capacity. The conditions for obtaining biodiesel were optimized by selecting the catalyst and varying the percentage of catalyst, the methanol/oil ratio and the reaction time. The catalysts reached yields of conversion to biodiesel of up to 96% in 20 min of reaction using only 2% catalyst. The catalyst that showed the best catalytic activity contains a mixture of predominant crystalline and amorphous phases of CoFe2O4 and NaxCoO2. The results suggest that cobalt is a determinant in the activity of the catalyst when forming active sites in the crystalline network of mixed oxides for the transesterification of triglycerides, with high conversion capacity and selectivity to biodiesel.

Synthesis of Ethylene-Propylene Copolymer and their Structures

2014 ◽  
Vol 1035 ◽  
pp. 149-154
Author(s):  
Yan Liu Dang ◽  
Yun Zhao ◽  
Chao Xiang Wang ◽  
Qing Ze Jiao ◽  
Han Sheng Li ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Glass Transition ◽  
Resonance Spectroscopy ◽  
Differential Scanning Calorimetry Analysis ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Ethylene Propylene ◽  
X Ray

This work reports copolymerization of ethylene-propylene (EP) using a novel phenoxy–ester ligated titanium catalyst. Copolymerization reactions were conducted in toluene at 70 °C with varied E/P flow ratios. Fourier transform infrared spectroscopy, X-ray diffractometer, nuclear magnetic resonance spectroscopy and differential scanning calorimetry analysis were performed to characterize the structures, compositions and glass transition temperatures of the copolymers. The results show that ethylene-propylene copolymers are random polymers and the link ratios of ethylene to propylene are between 0.89 and 1.26. The glass transition temperature of ethylene-propylene copolymer is-43.3 °C.

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

scholarly journals Searching novel complex solid solution electrocatalysts in unconventional element combinations

Nano Research ◽  
2021 ◽  
Author(s):  
Olga A. Krysiak ◽  
Simon Schumacher ◽  
Alan Savan ◽  
Wolfgang Schuhmann ◽  
Alfred Ludwig ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Active Sites ◽  
Search Space ◽  
Reduction Reaction ◽  
Film Material ◽  
X Ray ◽  
High Entropy ◽  
Catalyst Composition ◽  
Scanning Transmission

AbstractDespite outstanding accomplishments in catalyst discovery, finding new, more efficient, environmentally neutral, and noble metal-free catalysts remains challenging and unsolved. Recently, complex solid solutions consisting of at least five different elements and often named as high-entropy alloys have emerged as a new class of electrocatalysts for a variety of reactions. The multicomponent combinations of elements facilitate tuning of active sites and catalytic properties. Predicting optimal catalyst composition remains difficult, making testing of a very high number of them indispensable. We present the high-throughput screening of the electrochemical activity of thin film material libraries prepared by combinatorial co-sputtering of metals which are commonly used in catalysis (Pd, Cu, Ni) combined with metals which are not commonly used in catalysis (Ti, Hf, Zr). Introducing unusual elements in the search space allows discovery of catalytic activity for hitherto unknown compositions. Material libraries with very similar composition spreads can show different activities vs. composition trends for different reactions. In order to address the inherent challenge of the huge combinatorial material space and the inability to predict active electrocatalyst compositions, we developed a high-throughput process based on co-sputtered material libraries, and performed high-throughput characterization using energy dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (SEM), X-ray diffraction (XRD) and conductivity measurements followed by electrochemical screening by means of a scanning droplet cell. The results show surprising material compositions with increased activity for the oxygen reduction reaction and the hydrogen evolution reaction. Such data are important input data for future data-driven materials prediction.

scholarly journals Changes of Pd Oxidation State in Pd/Al2O3 Catalysts Using Modulated Excitation DRIFTS

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 116
Author(s):  
Gian Luca Chiarello ◽  
Ye Lu ◽  
Miren Agote-Arán ◽  
Riccardo Pellegrini ◽  
Davide Ferri
Keyword(s):  
Particle Size ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Oxidation State ◽  
Diffuse Reflectance ◽  
X Ray ◽  
Spectral Changes ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Reversible Reduction

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.

Controlling the Growth of ZnO-SiO2 Nanostructures Using Pt-Coated Si Substrate

2014 ◽  
Vol 548-549 ◽  
pp. 354-357 ◽  
Author(s):  
Amber Dea Marie V. Peguit ◽  
Rolando T. Candidato ◽  
Reynaldo M. Vequizo ◽  
Majvell Kay G. Odarve ◽  
Bianca Rae B. Sambo ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Active Sites ◽  
Zno Nanostructures ◽  
Si Substrate ◽  
X Ray ◽  
Si Substrates ◽  
Scanning Electron ◽  
Pronounced Peak

ZnO-SiO2 nanostructures were grown on both bare Si and Pt-coated Si substrates via chemical bath deposition (CBD). The grown nanostructures were characterized using Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy (SEM-EDS), Fourier Transform Infrared (FTIR) measurement and Ultraviolet-Visible (UV-Vis) absorption spectroscopy. Surface morphology results revealed that Pt-coated Si substrate have promoted the growth of ZnO-SiO2 nanostructures by providing more active sites for nucleation thus formation ZnO-SiO2 nanostructures were observed. It is believed that SiO2 will adhere to the non-polar sides of the grown ZnO nanostructures. This result is manifested in the FTIR spectra which showed a pronounced peak corresponding to ZnO-SiO2 grown on bare Si suggesting that more Si-O bonds are present. However, Pt-coating did not significantly affect the band gap of the grown ZnO-SiO2 nanostructures.

scholarly journals COMPARISON STUDY OF GRINDING AND SLURRY METHOD ON PHYSICOCHEMICAL CHARACTERISTIC OF ACYCLOVIR – SUCCINIC ACID COCRYSTAL

2017 ◽  
Vol 10 (3) ◽  
pp. 153
Author(s):  
Fauzi Rahman ◽  
Agnes Nuniek Winantari ◽  
Dwi Setyawan ◽  
Siswandono .
Keyword(s):  
Fourier Transform ◽  
Ir Spectroscopy ◽  
Succinic Acid ◽  
Physicochemical Characteristic ◽  
Fourier Transform Infrared ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Slurry Method ◽  
Dissolution Efficiency

ABSTRACTObjective: This study aimed to compare the characteristics of acyclovir (ACV)-succinic acid (SA) cocrystal with grinding and slurry method.Methods: Cocrystals were prepared using grinding and slurry methods. Physicochemical characterizations were performed using powder X-raydiffraction (PXRD), differential scanning calorimetry, Fourier transform infrared (IR) spectroscopy, scanning electron microscope (SEM), anddissolution test.Results: The study revealed that cocrystal of ACV-SA showed a decrease in the melting temperature, i.e., 175.10°C, respectively, in comparison with themelting point of the constituent materials (ACV 253.53°C and SA 187.29°C). PXRD diffractogram showed that cocrystal with grinding method exhibitednew diffraction peaks at angle 2θ=8.92°, 16.24°, and 17.14°, while PXRD diffractogram of cocrystal with slurry method exhibit new diffraction peaksat angle 2θ=16.25°, and 19.63°. Characterization with IR spectroscopy showed the disappearance of transmission peaks at 3441cm disappearance ofC=O stretch at 1584cm and 1612cm. Dissolution efficiency of each treatment group calculated the efficiency of dissolution in 15th minutes, grindingmethod cocrystal with grinding time 15 minutes give the dissolution efficiency were 54.23%. Slurry method cocrystal with solvent concentration12 ml/g gives the high value of the dissolution efficiency is 74.36%. SEM micrographs showed that cocrystals prepared by solvent evaporation methodhave differences crystal form at magnification 5000× magnification compared to pure ACV and physical mixture.Conclusion: The study concluded that cocrystals of ACV-SA were successfully formed using grinding and slurry methods. The formed cocrystalsof ACV-SA exhibited different physicochemical characteristics as compared to the constituent materials. The formed cocrystals prepared by slurrymethod have a high intensity of diffraction peak on X-ray diffraction and highest dissolution efficiency at 15 minutes rather than grinding methodcocrystal.Keywords: Cocrystal, Acyclovir, Succinic acid, Grinding, Slurry, Powder X-ray diffraction, Fourier transform infrared, Dissolution rate. 

scholarly journals Lanthanide metal–organic frameworks: Structural, thermal and sorption properties

2017 ◽  
Vol 35 (7-8) ◽  
pp. 677-683 ◽  
Author(s):  
Renata Łyszczek ◽  
Liliana Mazur ◽  
Agnieszka Ostasz ◽  
Agata Bartyzel ◽  
Halina Głuchowska
Keyword(s):  
Fourier Transform ◽  
Three Dimensional ◽  
Bet Surface Area ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Pore Size Distributions ◽  
Metal Organic ◽  
Lanthanide Metal ◽  
Solvothermal Conditions ◽  
Dimethylformamide Solution

Two coordination polymers of erbium(III) and neodymium(III) ions with 1,3,5-benzenetricarboxylic acid were synthesized under the solvothermal conditions from the dimethylformamide solution. They were characterized by the attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR), thermogravimetry and differential scanning calorimetry (TG-DSC), thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) and X-ray diffractions methods. The single-crystal X-ray analysis confirmed formation of three-dimensional framework of Er(III) 1,3,5-benzenetricarboxylate with the channels occupied by dimethylformamide and water molecules. Porosity of crystalline complexes was investigated by the nitrogen sorption experiments. The Nd and Er compounds exhibit real porosity with the BET surface area of 259 and 225 m2/g, respectively. The Horvath–Kawazoe analysis of pore-size distributions for the obtained complexes points out to their microporous character.

scholarly journals Heterostructural Mixed Oxides Prepared via ZnAlLa LDH or ex-ZnAl LDH Precursors—Effect of La Content and Its Incorporation Route

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2082
Author(s):  
Katarzyna Antoniak-Jurak ◽  
Paweł Kowalik ◽  
Wiesław Próchniak ◽  
Robert Bicki ◽  
Grzegorz Słowik
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Thermal Treatment ◽  
Mixed Oxides ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Znal2o4 Spinel

The effect of La content and its incorporation route on physicochemical properties of ZnO/Zn(Al,La)2O4 or La2O3–ZnO/ZnAl2O4 mixed oxides with a spinel structure obtained from ZnAlLa Layered double hydroxides (LDHs) or ex-ZnAl LDH materials was investigated. The heterostructural nanocomposites with the similar Zn/Al molar ratio and varied La content were prepared by two techniques: via co-precipitation and thermal treatment of ZnAlLa LDHs at 500 °C or via incipient wetness impregnation of ex-ZnAl LDHs with aqueous solutions of lanthanum nitrate and subsequent thermal treatment. The obtained series of materials were characterized by the following techniques: X-ray fluorescence (XRF), N2 adsorption (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis with evolved gas analysis (TG/DTG/EGA), scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared spectroscopy (FFT). The evaluation of activity toward the high-temperature water gas shift (HT-WGS) within the temperature range of 350–420 °C was carried out on the basis of rate constant measurements in the kinetic mode using a differential reactor. The co-precipitation technique allowed for a better distribution of La in bulk and on the spinel surface than in case of lanthanum incorporation via impregnation. ZnO/Zn(Al,La)2O4 or La2O3–ZnO/ZnAl2O4 mixed oxides were characterized by moderate activity in the HT-WGS reaction. The results reveal that introduction of lanthanum oxide over 2.4–2.8 wt% induces the phase separation of the ZnAl2O4 spinel, forming ZnO on the ZnAl2O4 spinel surface.

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