scholarly journals Cyclodehydration of 1,4-butanediol over Zr-Al Catalysts: Effect of Reaction Medium

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2092 ◽  
Author(s):  
Kuo-Tseng Li ◽  
Kuan-Wen Chen
Keyword(s):  
Surface Area ◽  
Rate Constant ◽  
Active Sites ◽  
Mixed Oxides ◽  
Reaction Medium ◽  
Adsorbed Water ◽  
Precipitation Method ◽  
Catalyst Composition ◽  
Catalyst Acidity ◽  
Co Precipitation

The conversion of 1,4-butanediol (BDO) to tetrahydrofuran (THF) in aqueous phase is desirable because BDO production technology is shifting to bio-based aqueous fermentation routes. In this study, liquid-phase cyclodehydration of BDO to THF was studied in two reaction media (pure BDO and aqueous BDO feeds) at 200–240 °C using ZrO2-Al2O3 (ZA) mixed oxides, which were made with a co-precipitation method and were characterized with XRD, BET, SEM/EDX, pyridine and n-butylamine adsorptions. The maximum acidity and the largest surface area occurred at Zr/Al atomic ratios of 1/1 (ZA11) and 1/3 (ZA13), respectively. The reaction exhibited pseudo-first-order; aqueous BDO feed had much greater rate constant than pure BDO feed, ascribed to the acidic properties of adsorbed water molecules (coordinated to surface metal cations) for the former case. For pure BDO feed, linear relation was observed between rate constant and catalyst acidity, and ZA11 reached a THF yield of 90.1% at 240 °C. With aqueous BDO feed, rate constant increased linearly with increasing surface area and ZA13 reached a THF yield of 97.1% at 220 °C. The change of optimum catalyst composition with reaction medium suggests that active sites for catalyzing BDO cyclodehydration changed with the reaction environment.

scholarly journals Bio-DEE Synthesis and Dehydrogenation Coupling of Bio-Ethanol to Bio-Butanol over Multicomponent Mixed Metal Oxide Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 660
Author(s):  
Izabela S. Pieta ◽  
Alicja Michalik ◽  
Elka Kraleva ◽  
Dusan Mrdenovic ◽  
Alicja Sek ◽  
...  
Keyword(s):  
Active Sites ◽  
Internal Combustion Engines ◽  
Mixed Oxides ◽  
Catalyst Activity ◽  
Product Distribution ◽  
Coke Deposition ◽  
Precipitation Method ◽  
Mixed Metal Oxide ◽  
Low Carbon ◽  
Municipal Solid Wastes

Within the Waste2Fuel project, innovative, high-performance, and cost-effective fuel production methods from municipal solid wastes (MSWs) are sought for application as energy carriers or direct drop-in fuels/chemicals in the near-future low-carbon power generation systems and internal combustion engines. Among the studied energy vectors, C1-C2 alcohols and ethers are mainly addressed. This study presents a potential bio-derived ethanol oxidative coupling in the gas phase in multicomponent systems derived from hydrotalcite-containing precursors. The reaction of alcohol coupling to ethers has great importance due to their uses in different fields. The samples have been synthesized by the co-precipitation method via layered double hydroxide (LDH) material synthesis, with a controlled pH, where the M(II)/M(III) ≈ 0.35. The chemical composition and topology of the sample surface play essential roles in catalyst activity and product distribution. The multiple redox couples Ni2+/Ni3+, Cr2+/Cr3+, Mn2+/Mn3+, and the oxygen-vacant sites were considered as the main active sites. The introduction of Cr (Cr3+/Cr4+) and Mn (Mn3+/Mn4+) into the crystal lattice could enhance the number of oxygen vacancies and affect the acid/base properties of derived mixed oxides, which are considered as crucial parameters for process selectivity towards bio-DEE and bio-butanol, preventing long CH chain formation and coke deposition at the same time.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Synthesis of Magnetic Modified Organobentonite as Adsorbent for Degradation of Orange II

2013 ◽  
Vol 838-841 ◽  
pp. 2306-2309
Author(s):  
Guang Hua Wang ◽  
Kun Chen ◽  
Wen Bing Li ◽  
Dong Wan ◽  
Qin Hu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Reaction Medium ◽  
Precipitation Method ◽  
Basal Spacing ◽  
Orange Ii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Co Precipitation ◽  
Scanning Electron

Magnetic modified organobentonite (Fe3O4/CTAB–Bent) was synthesized by chemical co-precipitation method in which CTAB–Bent was firstly achieved via ion–exchange.The composite materials have been characterized by powder X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR) and Scanning electron microscopy (SEM) . The results revealed that basal spacing of bentonite was increased through organic modification and the Fe3O4 particles synthesized which covering the surfaces of bentonite .Compared with natural bentonite, the adsorption capacity of Fe3O4/CTAB–Bent for Orange II was greatly enhanced and can be easily separated from the reaction medium by an external magnetic field after the treatment.

scholarly journals Effect of Copper Cobalt Oxide Composition on Oxygen Evolution Electrocatalysts for Anion Exchange Membrane Water Electrolysis

2020 ◽  
Vol 8 ◽  
Author(s):  
Chae-Yeon Kwon ◽  
Jae-Yeop Jeong ◽  
Juchan Yang ◽  
Yoo Sei Park ◽  
Jaehoon Jeong ◽  
...  
Keyword(s):  
Cobalt Oxide ◽  
Anion Exchange ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Anion Exchange Membrane ◽  
Electrochemical Kinetics ◽  
Precipitation Method ◽  
Energetic Efficiency ◽  
Co Precipitation ◽  
Exchange Membrane

Copper cobalt oxide nanoparticles (CCO NPs) were synthesized as an oxygen evolution electrocatalyst via a simple co-precipitation method, with the composition being controlled by altering the precursor ratio to 1:1, 1:2, and 1:3 (Cu:Co) to investigate the effects of composition changes. The effect of the ratio of Cu2+/Co3+ and the degree of oxidation during the co-precipitation and annealing steps on the crystal structure, morphology, and electrocatalytic properties of the produced CCO NPs were studied. The CCO1:2 electrode exhibited an outstanding performance and high stability owing to the suitable electrochemical kinetics, which was provided by the presence of sufficient Co3+ as active sites for oxygen evolution and the uniform sizes of the NPs in the half cell. Furthermore, single cell tests were performed to confirm the possibility of using the synthesized electrocatalyst in a practical water splitting system. The CCO1:2 electrocatalyst was used as an anode to develop an anion exchange membrane water electrolyzer (AEMWE) cell. The full cell showed stable hydrogen production for 100 h with an energetic efficiency of >71%. In addition, it was possible to mass produce the uniform, highly active electrocatalyst for such applications through the co-precipitation method.

Selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over MnOx–CeO2 composite catalysts

2017 ◽  
Vol 19 (4) ◽  
pp. 996-1004 ◽  
Author(s):  
Xuewang Han ◽  
Chaoqun Li ◽  
Xiaohui Liu ◽  
Qineng Xia ◽  
Yanqin Wang
Keyword(s):  
Selective Oxidation ◽  
Noble Metal ◽  
Mixed Oxides ◽  
Aerobic Oxidation ◽  
Metal Catalysts ◽  
Precipitation Method ◽  
Composite Catalysts ◽  
Noble Metal Catalysts ◽  
Furandicarboxylic Acid ◽  
Co Precipitation

Non-noble metal catalysts, MnOx–CeO2 mixed oxides, were prepared by a co-precipitation method and used in the direct aerobic oxidation of HMF to FDCA, showing excellent catalystic activity and stability.

scholarly journals The Influence of the Preparation Method on the Physico-Chemical Properties and Catalytic Activities of Ce-Modified LDH Structures Used as Catalysts in Condensation Reactions

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6191
Author(s):  
Alexandra-Elisabeta Stamate ◽  
Rodica Zăvoianu ◽  
Octavian Dumitru Pavel ◽  
Ruxandra Birjega ◽  
Andreea Matei ◽  
...  
Keyword(s):  
Preparation Method ◽  
Mixed Oxides ◽  
Condensation Reaction ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Molar Ratios ◽  
Base Catalysts ◽  
Physico Chemical ◽  
Co Precipitation

Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.

scholarly journals The Fabrication of Natural Zeolite Via Co-Precipitation Method as Cu, Pb and Zn Metal Absorbent

2020 ◽  
Vol 57 (3) ◽  
pp. 40-47
Author(s):  
M. Sirait ◽  
K.Sari Dewi Saragih ◽  
S. Gea ◽  
Keyword(s):  
Heavy Metal ◽  
Surface Area ◽  
Natural Zeolite ◽  
Total Surface Area ◽  
Precipitation Method ◽  
Natural Material ◽  
X Ray Diffraction ◽  
Test Analysis ◽  
Living Things ◽  
Co Precipitation

AbstractHeavy metal waste is very dangerous, which can change the condition of water into a solid substance that can be suspended in water and can reduce the cleanliness level of water consumed by living things. To date, heavy metals can be managed through several processes, namely physics, biology or chemistry. One of the ways to overcome heavy metal pollution is to use natural zeolite applying a co-precipitation method, as it is known that zeolite is a powerful natural material to be used for certain purposes. In order to justify the research results, several analyses have been performed, such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Surface Area Analyser (SAA), and Atomic Adsorption Spectrophotometric (AAS). From the XRD results, it has been found out that the size of each zeolite with variations in size of 150 mesh, 200 mesh, and 250 mesh is 29.274 nm, 38.665 nm and 43.863 nm, respectively. Moreover, the SEM-EDX has shown that the zeolite under consideration is a type of Na-Zeolite and that the co-precipitation method successfully removes impurity elements, namely, Fe, Ti, and Cl. The results of SAA testing have indicated that the total surface area for each variation of zeolite sizes is 63.23 m2/g, 45.14 m2/g and 59.76 m2/g. The results of the AAS test analysis have demonstrated that the optimal absorption of metal content is observed in a size of 150 mesh zeolite with adsorption power of 99.6 % for Pb metal, 98 % for Cu metal, and 96 % Zn metal.

Catalytic Decomposition of Energetic Liquid Solution Over Various Types of Hexaaluminate Catalysts

2020 ◽  
Vol 20 (11) ◽  
pp. 7114-7118
Author(s):  
Youngmin Choi ◽  
Sujeong Heo ◽  
Munjeong Kim ◽  
Jeongsub Lee ◽  
Young Chul Park ◽  
...  
Keyword(s):  
Catalytic Decomposition ◽  
Liquid Solution ◽  
The Other ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Heat Treated ◽  
Powdered Catalyst ◽  
Co Precipitation

A hexaaluminate support was prepared by a co-precipitation method, and a metal (Cu, Pt, or Ir) was impregnated on the support to prepare a powdered catalyst. After that, organic and inorganic binders were added to the powdery catalyst and then pellets were formed. The so-formed catalysts were heat-treated at 1200°C, and their physicochemical properties were analyzed by N2-adsorption, X-ray diffraction (XRD), X-ray fluorenscence (XRF), and scanning electron microscopy (SEM). The decomposition activity of the catalysts on an ammonium dinitramide (ADN)-based liquid propellant was evaluated repeatedly, and the effects of catalyst composition and morphology on low temperature decomposition activity and durability were investigated. It was confirmed that the Cu-hexa-pellet, Pt-hexa-pellet, and Ir-hexa-pellet catalysts could be recovered and reused as a catalyst for decomposition of an ADN-based liquid monopropellant. The initial activity and the thermal stability of the Cu-hexa-pellet catalyst for the decomposition of ADN-based liquid monopropellants were better than for the other catalysts. The better activity of the Cu-hexa-pellet catalyst seems to be because the dispersion of the copper was higher than the metal dispersion in the other two catalysts.

Effects of La-Doping on the Structure and Performance of Copper-Manganese Oxides for the Water-Gas Shift Reaction

2012 ◽  
Vol 512-515 ◽  
pp. 2131-2134 ◽  
Author(s):  
Run Xia He ◽  
Quan Sheng Liu ◽  
Fang Wu ◽  
Chen Liang Zhou ◽  
Ke Duan Zhi ◽  
...  
Keyword(s):  
Manganese Oxides ◽  
Mixed Oxides ◽  
Raw Materials ◽  
Water Gas Shift ◽  
Precipitation Method ◽  
La Doping ◽  
Copper Manganese ◽  
Co Precipitation ◽  
Shift Reaction ◽  
Water Gas

By using copper manganese sulfated and lanthanum nitrate as raw materials, and NaOH as precipitating agent, the copper-manganese-lanthanum mixed oxides were prepared through co-precipitation method. The catalyst samples were characterized by XRD, TPR and TPD, and the catalytic properties on water gas shift (WGS) reaction were studied. The results show that, La doping didn’t change the crystal structure, but the sample crystallinity was deteriorated. Cu-Mn/La-0.5 sample reduction temperature was low and the adsorption quantity of activated CO2 was large, which implied that copper and manganese components have good metal synergic effect, lower temperature activity and thermal stability.

Study on Cu-Based Catalysts for Synthesis of Indole

2011 ◽  
Vol 295-297 ◽  
pp. 668-671 ◽  
Author(s):  
Jun De Xing ◽  
Xiao Fei Jia
Keyword(s):  
Grain Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Co Precipitation

A series of Cu-based catalysts for the synthesis of indole by the reaction of aniline and ethylene glycol were prepared and characterized by ICP-AES and XRD. The results indicated that the activity and stability of Cu/SiO2 catalyst was increased after adding Zn, Mn, Cr and Fe promoters. Mn promoter was favorable for the dispersion of Cu, Zn, Cr, Fe and enlarged the specific surface area of catalysts. It could be seen that the catalysts prepared by impregnation method had better stability and higher activity than the catalysts prepared by co-precipitation method. The catalysts with small grain size of Cu had higher activity than those with big grain size. Some catalysts showed excellent performances in this reaction.

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