Different Crystal Form Titania Supported Ruthenium Nanoparticles for Liquid Phase Hydrodeoxygenation of Guaiacol

2018 ◽  
Vol 18 (12) ◽  
pp. 8426-8436 ◽  
Author(s):  
Wei Long ◽  
Yang Lv ◽  
Pingle Liu ◽  
Fang Hao ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Reaction Path ◽  
Supported Catalyst ◽  
Crystal Form ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
Ruthenium Nanoparticles ◽  
Crystal Forms ◽  
Anatase Titania ◽  
Rutile Titania

Titania supported Ruthenium-based catalysts were prepared for liquid phase hydrodeoxygenation of guaiacol to cyclohexanol. The catalytic performance is affected by the different crystal forms of titania supports. Anatase and rutile titania supported catalyst 5%Ru/a-r-TiO2 presents higher BET surface area, better dispersion of Ru particles with smaller particle size of 3–4 nm, more acidic centers, and more Ruδ+ located at the boundary between anatase titania and rutile titania. Hence, 5%Ru/a-r-TiO2 gives the best catalytic performance of 95.33% conversion of guaiacol and 79.23% selectivity to cyclohexanol, other products mainly include cyclohexane, benzene, cyclohexanone and 1,2-cyclohexanediol. Based on the results of this work, the possible reaction path for guaiacol hydrodeoxygenation was proposed.

Study on Preparation and Photoelectrocatalytic Activity of Supported TiO2 Catalysts

2013 ◽  
Vol 807-809 ◽  
pp. 1555-1558
Author(s):  
Jing Miao ◽  
Hai Bin Yu ◽  
Yan Min Sun ◽  
Hou Kai Teng ◽  
Xiao Yun Liu ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Calcination Temperature ◽  
Active Component ◽  
Removal Rate ◽  
Supported Catalyst ◽  
Ammonium Fluoride ◽  
Crystal Form ◽  
Liquid Phase Deposition ◽  
Deposition Method ◽  
Loading Amount

TiO2/α-Al2O3is prepared by liquid-phase deposition method from titanium ammonium fluoride. The morphography and crystal form of supported catalyst are analyzed by XRD and SEM. The results show that anatase is detected when the calcination temperature is 800°C, the interaction of TiO2and support inhibit TiO2transfer into anatase. The addition of polyvinyl alcohol makes the active component evenly distributed. It is found that when support for catalyst is honeycomb column α-Al2O3, loading amount is 4.0%, and calcination temperature is 800°C, the CODcr removal rate could reach 66%. Furthermore, no obvious evidence of deactivation and intensity for the catalyst could be seen after running for 100 hours.

scholarly journals Ethylene Trimerization over Supported SNS and PNP

2021 ◽  
Vol 75 ◽  
Author(s):  
Chromium Catalysts ◽  
Mzamo L. Shozi ◽  
Xolelwa Zulu ◽  
Holger B. Friedrich
Keyword(s):  
Supported Catalysts ◽  
Supported Catalyst ◽  
Catalytic Performance ◽  
Phosphine Ligands ◽  
Bet Surface Area ◽  
Nitrogen And Phosphorus ◽  
Reaction Conditions ◽  
Tridentate Ligands ◽  
Ethylene Trimerization ◽  
Influence Of Temperature On

ABSTRACT Chromium(III) complexes with sulphur, nitrogen and phosphorus tridentate ligands were synthesized and characterized. These complexes were supported on SiO2 and characterized by BET surface area measurements, XRF, SEM-EDX and FTIR. The complexes were tested for activity and selectivity in the trimerization of ethylene. The substituent's effect and influence on the sulphur on the supported catalysts were studied using the ethyl and the decyl substituted catalysts. The influence of temperature on catalytic performance was evaluated using the PPP supported system. The most active supported catalyst, the decyl substituted SNS catalyst, showed good activity of up to 19 500 g/g Cr h-1 and selectivity of 97.3 % to C6 products (98.2 % 1-hexene). This activity and selectivity were comparable to the homogeneous counterpart's performance that achieved 22 000 g/g Cr h-1 and 98.2 % C6 products (96.7 % 1-hexene), which surpassed the ethyl substituted catalyst, which was not supported, under the same reaction conditions. The supported PPP catalyst activities showed it was sensitive to higher temperatures, but this depends on the supporting technique. Keywords: Ethylene trimerization, sulfanyl ligands, phosphine ligands, supported catalysts.

Photoconversion of 2-Propanol on Rutile Titania: A Combined Liquid-Phase and Surface Science Study

2021 ◽  
Vol 125 (6) ◽  
pp. 3355-3367
Author(s):  
Jessica Kräuter ◽  
Lars Mohrhusen ◽  
Fabian Waidhas ◽  
Olaf Brummel ◽  
Jörg Libuda ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Surface Science ◽  
Science Study ◽  
Rutile Titania ◽  
Surface Science Study

scholarly journals Metal-Organic Frameworks in Oxidation Catalysis with Hydrogen Peroxide

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 283
Author(s):  
Oxana Kholdeeva ◽  
Nataliya Maksimchuk
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Selective Oxidation ◽  
Metal Organic Frameworks ◽  
Short Review ◽  
Catalytic Performance ◽  
Oxidation Catalysis ◽  
Catalyst Stability ◽  
Aqueous Hydrogen Peroxide ◽  
Metal Organic

In recent years, metal–organic frameworks (MOFs) have received increasing attention as selective oxidation catalysts and supports for their construction. In this short review paper, we survey recent findings concerning use of MOFs in heterogeneous liquid-phase selective oxidation catalysis with the green oxidant–aqueous hydrogen peroxide. MOFs having outstanding thermal and chemical stability, such as Cr(III)-based MIL-101, Ti(IV)-based MIL-125, Zr(IV)-based UiO-66(67), Zn(II)-based ZIF-8, and some others, will be in the main focus of this work. The effects of the metal nature and MOF structure on catalytic activity and oxidation selectivity are analyzed and the mechanisms of hydrogen peroxide activation are discussed. In some cases, we also make an attempt to analyze relationships between liquid-phase adsorption properties of MOFs and peculiarities of their catalytic performance. Attempts of using MOFs as supports for construction of single-site catalysts through their modification with heterometals will be also addressed in relation to the use of such catalysts for activation of H2O2. Special attention is given to the critical issues of catalyst stability and reusability. The scope and limitations of MOF catalysts in H2O2-based selective oxidation are discussed.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

scholarly journals Tunable Nonlinear Optical Property of MnS Nanoparticles with Different Size and Crystal Form

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 34
Author(s):  
Zhihao Zhang ◽  
Pengchao Li ◽  
Yuzong Gu
Keyword(s):  
Optical Property ◽  
Nonlinear Optical ◽  
Nonlinear Optical Property ◽  
Nonlinear Refraction ◽  
Synthesis Method ◽  
Crystal Form ◽  
Optical Nonlinearity ◽  
Photon Absorption ◽  
Third Order ◽  
Crystal Forms

It is significant to study the reason that semiconductor material has adjustable third-order optical nonlinearity through crystal form and dimensions are changed. αMnS nanoparticles with different crystal forms and sizes were successfully prepared by one-step hydrothermal synthesis method and their size-limited third-order nonlinear optical property was tested by Z-scan technique with 30 ps laser pulses at 532 nm wavelength. Nanoparticles of different crystal forms exhibited different NLO (nonlinear optical) responses. γMnS had stronger NLO response than αMnS because of higher fluorescence quantum yield. Two-photon absorption and the nonlinear refraction are enhanced as size of nanoparticlesreduced. The nanoparticles had maximum NLO susceptibility which was 3.09 × 10−12 esu. Susceptibility of αMnS increased about nine times than that of largest nanoparticles. However, it was reduced when size was further decreased. This trend was explained by the effects of light induced dipole moments. And defects in αMnS nanoparticles also had effect on this nonlinear process. MnS nanoparticles had potential application value in optical limiting and optical modulation.

Vanadium-doped titania-pillared montmorillonite clay as a catalyst for selective catalytic reduction of NO by ammonia

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 665-672 ◽  
Author(s):  
K. Bahranowski ◽  
J. Janas ◽  
T. Machej ◽  
E. M. Serwicka ◽  
L. A. Vartikian
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Pillared Clay ◽  
Area Measurement ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Reduction Of No ◽  
Pillared Montmorillonite ◽  
Doped Titania

AbstractA series of V-doped titania-pillared clay catalysts, characterized by ICP-AES chemical analysis, X-ray diffraction, BET surface area measurement, and ESR spectroscopy, have been tested in the selective catalytic reduction of NO by NH3. An ESR analysis shows that V dopant is anchored to the titania pillars. Vanadyl species with differing degrees of in-plane V-O π-covalent bonding are produced depending on the method of sample preparation. Polymeric V species appear as the V content is increased. Catalytic performance of these systems depends on the method of preparation and on the V content. The best catalyst, converting 90-100% NO in the temperature range 523-623 K, is obtained by exchange of pillared montmorillonite with vanadyl ions, at an extent of exchange below the level where significant amounts of polymeric V species appear. The co-pillared catalyst, containing vanadyl centres characterized by a higher degree of in-plane ncovalent bonding (according to ESR), is less selective than the exchanged samples.

Crystallization and preliminary X-ray study of two crystal forms of Klebsiella oxytoca diol dehydratase–cyanocobalamin complex

1999 ◽  
Vol 55 (4) ◽  
pp. 907-909 ◽  
Author(s):  
Jun Masuda ◽  
Tetsuya Yamaguchi ◽  
Takamasa Tobimatsu ◽  
Tetsuo Toraya ◽  
Kyoko Suto ◽  
...  
Keyword(s):  
Klebsiella Oxytoca ◽  
Crystal Form ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Crystal Forms ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diol Dehydratase ◽  
Replacement Method

Two crystal forms of Klebsiella oxytoca diol dehydratase complexed with cyanocobalamin have been obtained and preliminary crystallographic experiments have been performed. The crystals belong to two different space groups, depending on the crystallization conditions. One crystal (form I) belongs to space group P212121 with unit-cell parameters a = 76.2, b = 122.3, c = 209.6 Å, and diffracts to 2.2 Å resolution using an X-ray beam from a synchrotron radiation source. The other crystal (form II) belongs to space group P21 with unit-cell parameters a = 75.4, b = 132.7, c = 298.8 Å, β = 91.9°, and diffracts to 3.0 Å resolution. For the purpose of structure determination, a heavy-atom derivative search was carried out and some mercuric derivatives were found to be promising. Structure analysis by the multiple isomorphous replacement method is now under way.

scholarly journals High-resolution structures of inhibitor complexes of human indoleamine 2,3-dioxygenase 1 in a new crystal form

2018 ◽  
Vol 74 (11) ◽  
pp. 717-724 ◽  
Author(s):  
Shukun Luo ◽  
Ke Xu ◽  
Shaoyun Xiang ◽  
Jie Chen ◽  
Chunyun Chen ◽  
...  
Keyword(s):  
Drug Discovery ◽  
High Resolution ◽  
Crystal Structures ◽  
Active Site ◽  
Crystal Form ◽  
Crystal Forms ◽  
Cellular Processes ◽  
Potential Target ◽  
Indoleamine 2,3 Dioxygenase

Human indoleamine 2,3-dioxygenase 1 (IDO1) is a heme-dependent enzyme with important roles in many cellular processes and is a potential target for drug discovery against cancer and other diseases. Crystal structures of IDO1 in complex with various inhibitors have been reported. Many of these crystals belong to the same crystal form and most of the reported structures have resolutions in the range 3.2–2.3 Å. Here, three new crystal forms of human IDO1 obtained by introducing a surface mutation, K116A/K117A, distant from the active site are reported. One of these crystal forms diffracted to 1.5 Å resolution and can be readily used for soaking experiments to determine high-resolution structures of IDO1 in complex with the substrate tryptophan or inhibitors that coordinate the heme. In addition, this mutant was used to produce crystals of a complex with an inhibitor that targets the apo form of the enzyme under the same conditions; the structure of this complex was determined at 1.7 Å resolution. Overall, this mutant represents a robust platform for determining the structures of inhibitor and substrate complexes of IDO1 at high resolution.

scholarly journals Environmentally Benign Neem Biodiesel Synthesis Using Nano-Zn-Mg-Al Hydrotalcite as Solid Base Catalysts

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Karthikeyan Chelladurai ◽  
Manivannan Rajamanickam
Keyword(s):  
Methyl Esters ◽  
Catalytic Performance ◽  
Environmentally Benign ◽  
Bet Surface Area ◽  
Molar Ratio ◽  
Solid Base ◽  
Synthetic Compound ◽  
Solid Base Catalysts ◽  
Base Catalysts ◽  
Biodiesel Synthesis

Hydrotalcite, also known as aluminum-magnesium layered double hydroxide (LDH) or anionic clay, is a synthetic compound that was broadly investigated in the past decade due to its many potential applications. In this work, we present an environmentally benign process for the transesterification (methanolysis) of neem oil to fatty acid methyl esters (FAME) using Zn-Mg-Al hydrotalcites as solid base catalysts in a heterogeneous manner. The catalysts were characterized by XRD, FT-IR, TPD-CO2, and the BET surface area analysis. It is well-known that the catalytic performance of hydrotalcite is dramatically increased through the incorporation of Zn into the surface of Mg-Al hydrotalcite material. The optimized parameters, 10 : 1 methanol/oil molar ratio with 7.5 g catalysts reacted under stirring speed 450 rpm at 65°C for 4 h reaction, gave a maximum ester conversion of 90.5% for the sample with Zn-Mg-Al ratio of 3 : 3 : 1.

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