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ChemEngineering, Volume 1, Issue 2 (December 2017)

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Open AccessArticle Hydrogen Utilization in Green Fuel Synthesis via CO2 Conversion to Methanol over New Cu-Based Catalysts
ChemEngineering 2017, 1(2), 19; https://doi.org/10.3390/chemengineering1020019
Received: 10 November 2017 / Revised: 6 December 2017 / Accepted: 14 December 2017 / Published: 19 December 2017
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Abstract
The use of hydrogen as an energy vector and raw material for “very clean liquid fuels” manufacturing has been assessed by the catalytic conversion of CO2 to methanol over copper based catalysts. A systematic evaluation of copper based catalysts, prepared varying the
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The use of hydrogen as an energy vector and raw material for “very clean liquid fuels” manufacturing has been assessed by the catalytic conversion of CO2 to methanol over copper based catalysts. A systematic evaluation of copper based catalysts, prepared varying the chemical composition, has been carried out at 0.1–5.0 MPa of total pressure and in the range of 453–513 K by using a semi-automated LAB-microplant, under CO2/H2 reactant mixture (1/3), fed at GHSV of 8.8 NL∙kgcat−1∙h−1. Material’s properties have been investigated by the means of chemical-physical studies. The findings disclose that the addition of structure promoters (i.e., ZrO2/CeO2) strongly improves the textural properties of catalysts, in term of total surface area and exposure of metal surface area (MSA), also reducing the sintering phenomena. The results of the catalytic study clearly prove a structure-activity relationship at low reaction pressure (0.1 MPa), while at higher pressure (3.0–5.0 MPa) the reaction path is insensitive to structure and chemical composition. Full article
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Open AccessArticle Effect of the Chemical Composition of Mesoporous Cerium-Zirconium Oxides on the Modification with Sulfur and Gold Species and Their Application in Glycerol Oxidation
ChemEngineering 2017, 1(2), 18; https://doi.org/10.3390/chemengineering1020018
Received: 15 November 2017 / Revised: 8 December 2017 / Accepted: 13 December 2017 / Published: 18 December 2017
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Abstract
Ceria, zirconia, and mixed cerium-zirconium mesoporous oxides were synthesized and used as supports for sulfur and gold species. The materials were characterised using selected advanced techniques (Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), elemental analysis, X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), N
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Ceria, zirconia, and mixed cerium-zirconium mesoporous oxides were synthesized and used as supports for sulfur and gold species. The materials were characterised using selected advanced techniques (Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), elemental analysis, X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), N2 adsorption, and desorption isotherms, Ultraviolet-Visible Spectroscopy (UV-vis), Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR), Temperature Programmed Reduction (TPR-H2), Thermogravimetric and Differential Thermal Analysis (TG-DTA)), which allowed for monitoring of the oxidation state of metals (cerium and gold) and the surface properties of the catalysts, in particular the concentration of the components on the surface and in the bulk of materials. The interactions between gold, sulfur, and metals from oxides were considered. The goal of this work was studied the changes in the chemical composition of materials and the oxidation states of cerium species after the modification of oxides with sulfur and gold species and the estimation of the influence of these changes on the surface properties. The chemical composition of surface affects the mobility of surface oxygen and the oxidation state of cerium, which can play the role of redox sites (e.g., Ce3+/Ce4+ species), and therefore it strongly influences the adsorption of hydrogen sulfide and then gold loading. Additionally, gold catalysts modified with sulfur species were tested in the reaction of glycerol oxidation in the liquid phase at basic conditions as the test reaction of the catalytic oxidation of organic pollutants from water. Full article
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Open AccessCommunication Oxidative Depolymerization of Lignin Using Supported Niobium Catalysts
ChemEngineering 2017, 1(2), 17; https://doi.org/10.3390/chemengineering1020017
Received: 18 October 2017 / Revised: 17 November 2017 / Accepted: 20 November 2017 / Published: 29 November 2017
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Abstract
Valorization of lignin into aromatics has driven researchers for decades. In this research, niobium was deposited on oyster shells (OSNC) and carbon rods (CRNC) and tested as a catalyst for depolymerization of lignin. Catalysts (2%, 5%, and 8% loading) were synthesized via wet
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Valorization of lignin into aromatics has driven researchers for decades. In this research, niobium was deposited on oyster shells (OSNC) and carbon rods (CRNC) and tested as a catalyst for depolymerization of lignin. Catalysts (2%, 5%, and 8% loading) were synthesized via wet impregnation. Batch experiments were performed at 95 °C, using 8 g of lignin, and 1 g of catalyst. Our research indicates that niobium supported catalysts are effective in partial oxidation of lignin. Maximum vanillin concentration for OSNC was found to be 86.25 mg L−1 (0.1 wt%) at 5% niobium whereas, as for CRNC, maximum vanillin concentration was found to be 139.40 mg L−1 (0.17 wt%) at 2% niobium loading. Addition of hydrogen peroxide into the batch reactor decreased the concentration of vanillin production. Full article
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Open AccessArticle Effects of Grafting Azacrown Ether on Thermal and Swelling Properties of Chitosan Films
ChemEngineering 2017, 1(2), 16; https://doi.org/10.3390/chemengineering1020016
Received: 20 September 2017 / Revised: 7 November 2017 / Accepted: 15 November 2017 / Published: 17 November 2017
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Abstract
The thermal and swelling properties of a series of azacrown ether-crosslinked chitosans prepared with varying molar amounts of N,N-diallyl-7,13-diaza-1,7,10,16-tetraoxa-dibenzo-18-crown-6 (molar equivalents ranging from 0, 0.125, 0.167, 0.25 and 0.5) films were studied with Thermographimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical
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The thermal and swelling properties of a series of azacrown ether-crosslinked chitosans prepared with varying molar amounts of N,N-diallyl-7,13-diaza-1,7,10,16-tetraoxa-dibenzo-18-crown-6 (molar equivalents ranging from 0, 0.125, 0.167, 0.25 and 0.5) films were studied with Thermographimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical analysis (DMA) techniques and swelling kinetics. Introducing the azacrown (DAC) as crosslinker into the chitosan matrices (Ch) altered the thermal and swelling properties of the chitosan/crown ether films (Ch-DAC) systematically with respect to molar ratios. At lower DAC content, a depression of Tg revealed a dominating internal plasticization effect of DAC on chitosan, while higher DAC molar ratios systematically increased the Tg of the network. The films high swelling capacity (as high as 1200%) was reached within three hours in aqueous acidic media and decreased systematically with increasing DAC content. The swelling behavior was highly dependent on pH and followed second order kinetics. Understanding the thermal and swelling properties of this series of azacrown ether-crosslinked chitosans sets the stage to further shed light on their impact for heavy metal adsorption in water remediation applications. Full article
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Open AccessArticle Enhanced Antioxidant Activity of Capsicum annuum L. and Moringa oleifera L. Extracts after Encapsulation in Microemulsions
ChemEngineering 2017, 1(2), 15; https://doi.org/10.3390/chemengineering1020015
Received: 15 October 2017 / Revised: 12 November 2017 / Accepted: 13 November 2017 / Published: 16 November 2017
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Abstract
Carotenoids are powerful natural antioxidants that can easily degrade and are almost insoluble in water. Their incorporation into microemulsions (MEs) can solve these problems. In this study, ethanol extracts (prepared using different protocols) of Capsicum annuum L. (green and red), Moringa oleifera L.
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Carotenoids are powerful natural antioxidants that can easily degrade and are almost insoluble in water. Their incorporation into microemulsions (MEs) can solve these problems. In this study, ethanol extracts (prepared using different protocols) of Capsicum annuum L. (green and red), Moringa oleifera L. leaves, and their mixtures [Red Pepper/Μ. oleifera (50/50 w/w) and Green Pepper/M. oleifera (50/50 w/w)], were encapsulated in MEs for the first time. The encapsulation efficiency was determined and the physicochemical characteristics of the prepared MEs were assessed by particle size, turbidity, centrifugation, and thermal stress determination. The antioxidant activity of extracts and their MEs was determined by the DSC and DPPH methods. Prepared MEs did not present phase separation, creaming, sedimentation, presence of aggregates, or other unacceptable macroscopic drawbacks. Turbidity measurements showed that only small differences in optical density appeared. MEs’ particle size dispersion was found to be around the average value and varied between 10 and 95 nm. The highest resistance to oxidation of crude extracts was observed by the M. oleifera leaf extract, followed by that of Red Pepper/Μ. oleifera (50/50 w/w) mixture, Green Pepper/M. oleifera (50/50 w/w) mixture, Red Pepper and, finally, Green Pepper. The results concerning MEs-encapsulated samples followed the same trend. Full article
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Open AccessFeature PaperArticle Hydrogen and Deuterium Solubility in Commercial Pd–Ag Alloys for Hydrogen Purification
ChemEngineering 2017, 1(2), 14; https://doi.org/10.3390/chemengineering1020014
Received: 20 October 2017 / Revised: 6 November 2017 / Accepted: 9 November 2017 / Published: 12 November 2017
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Abstract
Pd–Ag alloys with compositions close to 23–25% Ag are considered as a benchmark for hydrogen permeability. They are used in small scale reactors for hydrogen separation and purification. Permeability and solubility are strictly mathematically correlated, and the temperature dependence of solubility can provide
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Pd–Ag alloys with compositions close to 23–25% Ag are considered as a benchmark for hydrogen permeability. They are used in small scale reactors for hydrogen separation and purification. Permeability and solubility are strictly mathematically correlated, and the temperature dependence of solubility can provide useful information about the physical state of the material, the hydrogenation enthalpy, and the occurrence of different thermodynamic states. While the permeability of Pd–Ag alloys has been largely investigated, solubility measurements are available only in a restricted temperature range. In this paper, we extend solubility measurements up to 7 bar for Pd77Ag23 in the temperature range between 25 °C and 400 °C and for Pd30Ag70 for temperatures between 190 °C and 300 °C. The occurrence of solid solutions or hydride phases is discussed, and the hydrogenation enthalpy is calculated. Full article
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Open AccessArticle Airflow Management in Solid Oxide Electrolyzer (SOE) Operation: Performance Analysis
ChemEngineering 2017, 1(2), 13; https://doi.org/10.3390/chemengineering1020013
Received: 5 September 2017 / Revised: 26 October 2017 / Accepted: 26 October 2017 / Published: 6 November 2017
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Abstract
Hydrogen is being studied as a means of energy storage and can be synthetized to store renewable energy and successively used as a fuel for power production or transport purposes. High temperature solid oxide electrolyzers (SOE) are proposed as a technology to produce
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Hydrogen is being studied as a means of energy storage and can be synthetized to store renewable energy and successively used as a fuel for power production or transport purposes. High temperature solid oxide electrolyzers (SOE) are proposed as a technology to produce hydrogen with high energy efficiency and high power density. Within the studies on SOE operation, little attention has been given to the oxygen electrode side, where air is normally used as a sweep gas. In this study, we consider the option of reducing the air flow rate when operating an SOE stack. The advantages in terms of efficiency are calculated, showing that efficiency increases up to 2.8% when reducing the air flow rate down to 7% of nominal value. Full article
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Open AccessFeature PaperArticle Dissolution of Trihexyltetradecylphosphonium Chloride in Supercritical CO2
ChemEngineering 2017, 1(2), 12; https://doi.org/10.3390/chemengineering1020012
Received: 20 September 2017 / Revised: 27 October 2017 / Accepted: 30 October 2017 / Published: 3 November 2017
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Abstract
We present steady-state and time-resolved fluorescence spectroscopic data derived from coumarin 153 (C153) in a binary solution comprised of trihexyltetradecylphosphonium chloride ([P6,6,6,14]+Cl) and supercritical CO2 (scCO2). Steady-state fluorescence of C153 was measured in neat
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We present steady-state and time-resolved fluorescence spectroscopic data derived from coumarin 153 (C153) in a binary solution comprised of trihexyltetradecylphosphonium chloride ([P6,6,6,14]+Cl) and supercritical CO2 (scCO2). Steady-state fluorescence of C153 was measured in neat scCO2 and ionic liquid (IL)-modified scCO2 solutions. The steady-state excitation and emission peak frequency data in neat scCO2 and IL/scCO2 diverge at low fluid density (ρr = ρ/ρc < 1). The prominent spectral differences at low fluid density provided clear evidence that C153 reports different microenvironments, and suggested that the IL is solubilized in the bulk scCO2 and heterogeneity of the C153 microenvironment is readily controlled by scCO2 density. C153 dimers have been reported in the literature, and this formed the basis of the hypothesis that dimerization is occurring in scCO2. Time-dependent density functional theory (TD-DFT) electronic structure calculations yielded transition energies that were consistent with excitation spectra and provided supporting evidence for the dimer hypothesis. Time-resolved fluorescence measurements yielded triple exponential decays with time constants that further supported dimer formation. The associated fractional contributions showed that the dominant contribution to the intensity decay was from C153 monomers, and that in high density scCO2 there was minimal contribution from C153 dimers. Full article
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Open AccessArticle Oxidation of Glycerol with Unactivated Electroless CuNiMoP Catalyst
ChemEngineering 2017, 1(2), 11; https://doi.org/10.3390/chemengineering1020011
Received: 10 September 2017 / Revised: 24 October 2017 / Accepted: 25 October 2017 / Published: 27 October 2017
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Abstract
Unannealed CuNiMoP electrocatalyst was found active in electrochemical oxidation of glycerol, providing over 60% conversion without optimization. Prompted by this result, the same catalyst was investigated for the thermochemical oxidation of glycerol. For the thermochemical oxidation of glycerol using the as-deposited electroless CuNiMoP
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Unannealed CuNiMoP electrocatalyst was found active in electrochemical oxidation of glycerol, providing over 60% conversion without optimization. Prompted by this result, the same catalyst was investigated for the thermochemical oxidation of glycerol. For the thermochemical oxidation of glycerol using the as-deposited electroless CuNiMoP catalyst, a 23 full factorial design of experiments (two level factorial experiment design with three factors) to assess the influence of temperature (A), reaction time (B) and pressure (C). The major reaction products detected by high performance liquid chromatography (HPLC) were glyceric, hydroxypyruvic, tartronic, oxalic and formic acids. The factors found to be most significant for the production of glyceric and tartronic acids were A, B, C, AB and BC. The highest percent conversion obtained for 30-min and 60-min catalysts was 10.6% and 9.4%, respectively. The presence of lactic acid was observed only for the 60-min as-deposited electroless CuNiMoP/Al2O3 catalyst. The results suggest the feasibility of an inexpensive catalyst based on non-noble metals for the thermochemical oxidation of glycerol through the electroless deposition technique. Some differences exist between the thermochemical and electrochemical product selectivity of the CuNiMoP catalyst, and reasons are suggested for the observed differences. Full article
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Open AccessReview Ionic Liquid as Reaction Media for the Production of Cellulose-Derived Polymers from Cellulosic Biomass
ChemEngineering 2017, 1(2), 10; https://doi.org/10.3390/chemengineering1020010
Received: 28 July 2017 / Revised: 14 October 2017 / Accepted: 17 October 2017 / Published: 23 October 2017
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Abstract
The most frequent polymer on nature is cellulose that is present together with lignin and hemicellulose in vegetal biomass. Cellulose can be, in the future, sustainable raw matter for chemicals, fuels, and materials. Nevertheless, only 0.3% of cellulose is processed nowadays due to
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The most frequent polymer on nature is cellulose that is present together with lignin and hemicellulose in vegetal biomass. Cellulose can be, in the future, sustainable raw matter for chemicals, fuels, and materials. Nevertheless, only 0.3% of cellulose is processed nowadays due to the difficulty in dissolving it, and only a small proportion is used for the production of synthetic cellulosic fibers especially esters and other cellulose derivatives, normally in extremely polluting processes. The efficient and clean dissolution of cellulose is a major objective in cellulose research and development. Ionic liquids (ILs) are considered “green” solvents due to their low vapor pressure, that prevents them evaporating into the atmosphere. In addition, these molten salts present advantages in process intensification, leading to more than 70 patents in lignocellulosic biomass in ILs being published since 2005, most of them related to the production of cellulose derived polymers, e.g., acetates, benzoylates, sulfates, fuorates, phthalates, succinates, tritylates, or silylates. In this work, the use of ILs for production of cellulose derived polymers is thoroughly studied. To do so, in the first place, a brief summary of the state of the art in cellulose derivatives production is presented, as well as the main features of ILs in cellulose processing applications. Later, the main results in the production of cellulose derivatives using ILs are presented, followed by an analysis of the industrial viability of the process, considering aspects such as environmental concerns and ILs’ recyclability. Full article
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Open AccessArticle Mitigation of Cr(VI) Aqueous Pollution by the Reuse of Iron-Contaminated Water Treatment Residues
ChemEngineering 2017, 1(2), 9; https://doi.org/10.3390/chemengineering1020009
Received: 9 September 2017 / Revised: 6 October 2017 / Accepted: 8 October 2017 / Published: 11 October 2017
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Abstract
Reducing the levels of heavy metals in wastewaters below the permissible limits is imperative before they are discharged into the environment. At the same time, water treatment technologies should be not only efficient, but also affordable. In accordance with these principles, this study
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Reducing the levels of heavy metals in wastewaters below the permissible limits is imperative before they are discharged into the environment. At the same time, water treatment technologies should be not only efficient, but also affordable. In accordance with these principles, this study assessed the possibility of recovering iron-contaminated residues, resulting from the treatment of synthetic acid mine drainage, for the subsequent remediation of Cr(VI) polluted aqueous solutions. Bentonite, an inexpensive and available natural material, was used as an adsorbent for the removal of Fe(II) from synthetic acid mine drainage (AMD). Then, Fe(II)-contaminated bentonite, the residue generated during the treatment of AMD, was recovered and activated with sodium borohydride in order to convert the adsorbed Fe(II) to Fe(0). Subsequently, the Fe(0)-containing bentonite (Be-Fe(0)) was further used for the treatment of Cr(VI) contaminated aqueous solutions. Reactive materials investigated in this work were characterized by means of scanning electron microscopy-energy dispersive angle X-ray spectrometry (SEM-EDX), X-ray diffraction spectroscopy (XRD), point of zero charge, and image photographs. The effect of several important parameters (pH, temperature, metal concentration, and ionic strength) on both treatment processes was investigated and discussed. It was shown that the efficiency of Cr(VI) removal with Be-Fe(0) was much higher than with bentonite. On the basis of the present study it can be concluded that residues generated during the treatment of AMD with bentonite can be used as a cheap precursor for the production an Fe(0)-based reagent, with good Cr(VI) removal potential. Full article
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Open AccessArticle Photocatalytic Decolorization of Dye with Self-Dye-Sensitization under Fluorescent Light Irradiation
ChemEngineering 2017, 1(2), 8; https://doi.org/10.3390/chemengineering1020008
Received: 10 August 2017 / Revised: 16 September 2017 / Accepted: 30 September 2017 / Published: 5 October 2017
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Abstract
A dye-sensitization technique was applied to effective catalysts—TiO2 and ZnO—under fluorescent light irradiation for Orange II (OII) and Methyl Orange (MO) degradations. Treatments were carried out at different time periods using 20 mg of catalysts and 30 mL of 5 mg/L of OII
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A dye-sensitization technique was applied to effective catalysts—TiO2 and ZnO—under fluorescent light irradiation for Orange II (OII) and Methyl Orange (MO) degradations. Treatments were carried out at different time periods using 20 mg of catalysts and 30 mL of 5 mg/L of OII and MO. The degradation efficiency of OII and MO increased with increasing irradiation time under irradiation of fluorescent light. The photocatalytic activity of ZnO nanoparticles was better compared with that of TiO2 for MO; and the ZnO activity was the same as TiO2 for OII photodegradation. Kinetic behavior was evaluated in terms of the Langmuir–Hinshelwood model (pseudo-first order kinetic). The possible mechanism of photodegradation under fluorescent light was discussed. Full article
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