Improved ethanol dehydration catalysis by superior acid properties of Cs-impregnated silicotungstic acid supported on silica

2021 ◽  
Author(s):  
Robin Himmelmann ◽  
Elias Klemm ◽  
Michael Dyballa
Keyword(s):  
Reaction Temperature ◽  
Silicotungstic Acid ◽  
Ethanol Dehydration ◽  
Moderate Reaction ◽  
Acid Properties

We herein investigate the selective dehydration of ethanol at high conversions (>99.5%) at a moderate reaction temperature of only 493 K over a catalyst of silicotungstic acid (STA) supported on...

Structure, Acid Properties and Catalysis Performance of MCM-22 “Family” Zeolites on the Alkylation of Benzene with Propylene

2012 ◽  
Vol 549 ◽  
pp. 283-286 ◽  
Author(s):  
Fei Zhao ◽  
Yu Zhang ◽  
Shu Dong Geng ◽  
Lian Fa Chen ◽  
Wei Wang
Keyword(s):  
Catalytic Activity ◽  
Liquid Phase ◽  
Reaction Temperature ◽  
Dynamic Method ◽  
N2 Adsorption ◽  
Acid Properties ◽  
Low Reaction Temperature ◽  
Alkylation Of Benzene ◽  
Adsorption Desorption

MCM-22 “family” zeolites (MCM-22, MCM-49 and MCM-56) have been synthesized hydrothermally by dynamic method. All materials were characterized by different techniques, such as XRD, N2 adsorption-desorption and NH3-TPD. The catalyst performance of MCM-22 “family” zeolites have been studied on the alkylation of benzene with propylene in liquid phase. Result shows that MCM-22 “family” zeolites are excellent alkylation catalysts for the produce of cumene. Compared to MCM-22 and MCM-49, MCM-56 shows higher catalytic activity in a relatively low reaction temperature and higher monoalkylation selectivity in a relatively low benzene-to-propylene ratio.

scholarly journals Catalytic Dehydration of Ethanol over W/TiO2 Catalysts Having Different Phases of Titania Support

2019 ◽  
Vol 15 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Pongsatorn Kerdnoi ◽  
Chaowat Autthanit ◽  
Nithinart Chitpong ◽  
Bunjerd Jongsomjit
Keyword(s):  
Pore Structure ◽  
Diethyl Ether ◽  
Reaction Temperature ◽  
Catalytic Properties ◽  
Chemical Properties ◽  
Major Product ◽  
Ethanol Dehydration ◽  
Physico Chemical ◽  
Tio2 Support ◽  
Ether Yield

This study aims to investigate the catalytic behaviors on W/TiO2 catalysts having different phases of TiO2 towards catalytic dehydration of ethanol to higher value products including ethylene, diethyl ether, and acetaldehyde. In fact, TiO2 support with different crystalline phases can result in differences of physico-chemical properties of the catalyst. Therefore, the present work reports on the catalytic behaviors that were altered with different phases of TiO2 in catalytic ethanol dehydration to diethyl ether or ethylene as a major product. To prepare the catalysts, three different phases [anatase (A), rutile (R), and mixed phases (P25)] of TiO2 supports were impregnated with 10 wt% of tungsten (W). It was found that the W/TiO2-P25 catalyst revealed higher activity among other catalysts. At 300 °C, all catalysts can produce the diethyl ether yield of 24.1%, 22.8%, and 10.6% for W/TiO2-P25, W/TiO2-A, and W/TiO2-R catalysts, respectively. However, when the reaction temperature was increased to 400°C, ethylene is the major product. The W/TiO2-P25 and W/TiO2-A catalysts render the ethylene yield of 60.3% and 46.2%, respectively, whereas only 15.9% is obtained from W/TiO2-R catalyst. The most important parameter influencing their catalytic properties appears to be the proper pore structure, acidity, and distribution of W species. Copyright © 2019 BCREC Group. All rights reserved 

Esterification of Menthol and Lactic Acid by Silicotungstic Acid Catalyst Supported on Bentonite

2013 ◽  
Vol 634-638 ◽  
pp. 647-650
Author(s):  
Jian Zhong Jin ◽  
Na Bo Sun
Keyword(s):  
Lactic Acid ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Acid Catalyst ◽  
Molar Ratio ◽  
Main Reaction ◽  
Silicotungstic Acid ◽  
Optimum Conditions ◽  
Reaction Parameters ◽  
Acid Loading

The silicotungstic acid catalyst supported on bentonite was employed in the esterification of menthol and lactic acid. The main reaction parameters were silicotungstic acid loading on bentonite, the amounts of catalyst, molar ratio of reactants, reaction temperature and reaction time. The optimum conditions were determined as follows : silicotungstic acid loading on bentonite 50 wt %, catalyst 1.25 g , mole ratio of menthol to lactic acid 1:1.1, reaction temperature 130 °C and reaction time 3 h . The esterification yield of menthyl lactiate was about 83.97 %. The catalyst could be used repeatedly for many times without distinct loss in activity.

scholarly journals Polyethylene upcycling to long-chain alkylaromatics by tandem hydrogenolysis/aromatization

Science ◽  
2020 ◽  
Vol 370 (6515) ◽  
pp. 437-441 ◽  
Author(s):  
Fan Zhang ◽  
Manhao Zeng ◽  
Ryan D. Yappert ◽  
Jiakai Sun ◽  
Yu-Hsuan Lee ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Waste Disposal ◽  
Reaction Temperature ◽  
Molecular Hydrogen ◽  
Catalytic Conversion ◽  
Weight Percent ◽  
Low Molecular Weight ◽  
Moderate Reaction ◽  
High Yields ◽  
Long Chain

The current scale of plastics production and the accompanying waste disposal problems represent a largely untapped opportunity for chemical upcycling. Tandem catalytic conversion by platinum supported on γ-alumina converts various polyethylene grades in high yields (up to 80 weight percent) to low-molecular-weight liquid/wax products, in the absence of added solvent or molecular hydrogen, with little production of light gases. The major components are valuable long-chain alkylaromatics and alkylnaphthenes (average ~C30, dispersity Ð = 1.1). Coupling exothermic hydrogenolysis with endothermic aromatization renders the overall transformation thermodynamically accessible despite the moderate reaction temperature of 280°C. This approach demonstrates how waste polyolefins can be a viable feedstock for the generation of molecular hydrocarbon products.

Catalytic Synthesis of N-Butyl Acetate by Silicotungstic Acid Supported on Bentonite

2012 ◽  
Vol 550-553 ◽  
pp. 362-365
Author(s):  
Jian Zhong Jin
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Butyl Acetate ◽  
Molar Ratio ◽  
Main Reaction ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Silicotungstic Acid ◽  
Acid Loading

A series of solid acid catalysts were synthesized by incipient wetness impregnation method by varying the wt% of silicotungstic acid on bentonite. Silicotungstic acid supported on bentonite was used to catalytic synthesise of n-butyl acetate with acetic acid and n-butyl alcohol . The main reaction parameters such as silicotungstic acid loading on bentonite, the amount of catalyst, molar ratio of reactants, reaction temperature and reaction time have been investigated. The optimum conditions were determined as follows : silicotungstic acid loading on bentonite 20 wt %, catalyst 0.7 g , mole ratio of n-butanol to acetic acid 1:1.1, reaction temperature 98 °C and reaction time 2 h . The esterification yield of n-butyl acetate was about 98.2 %. The catalyst could be used repeatedly for many times without distinct loss in activity.

scholarly journals Catalytic transesterification of glycerol: Optimization for production of glycerol carbonate

2019 ◽  
Vol 15 (2) ◽  
pp. 131-138
Author(s):  
Po Kim Lo ◽  
Hor Yan Phin
Keyword(s):  
Reaction Time ◽  
Calcium Oxide ◽  
Reaction Temperature ◽  
Oxide Catalyst ◽  
Molar Ratio ◽  
Glycerol Carbonate ◽  
Temperature Reaction ◽  
Synergy Effect ◽  
Moderate Reaction ◽  
Central Composite

The purpose of this research was to study the effect of reaction temperature, reaction time and dimethyl carbonate:glycerol (DMC:Gly) molar ratio on the conversion of glycerol and yield of glycerol carbonate. The reaction was further optimized with central composite design (CCD), 15 runs of transesterification reaction were conducted. Meanwhile, the calcined calcium oxide catalyst was fixed at catalyst/glycerol molar ratio at 0.06 while the stirring rate was maintained at 1000 rpm for every runs. ANOVA results indicated that reaction temperature and reactants ratio (DMC:Gly) influenced the yield significantly. Synergy effect of reaction temperature with reaction time and reaction temperature with DMC:Gly molar ratio seem to have greater significance on the conversion instead of a single parameter. Under optimization studies, the maximum possible conversion and yield were 100% and 96.36% respectively which could be accomplished at 60.16 °C reaction temperature with 1.19 hour reaction time and 3.04 DMC:Gly molar ratio. Compared to the highest conversion (96.22%) and yield (95.83%) achieved before the optimization with reaction carried out at 60 °C, after 1.5 hours and at 3:1 DMC:Gly molar ratio, the optimization had resulted in the higher conversion with moderate reaction temperature and shorter reaction time.

Ultrastructure of Some Planktonic Formainifera

1974 ◽  
Vol 32 ◽  
pp. 190-191
Author(s):  
William H. Zucker
Keyword(s):  
Cell Biology ◽  
Water Mass ◽  
Planktonic Foraminifera ◽  
Uranyl Acetate ◽  
Ethanol Dehydration ◽  
Globigerinoides Ruber ◽  
Light Microscope Level ◽  
Globigerina Bulloides ◽  
Glutaraldehyde Solution ◽  
Diamond Knife

Planktonic foraminifera are widely-distributed and abundant zooplankters. They are significant as water mass indicators and provide evidence of paleotemperatures and events which occurred during Pleistocene glaciation. In spite of their ecological and paleological significance, little is known of their cell biology. There are few cytological studies of these organisms at the light microscope level and some recent reports of their ultrastructure.Specimens of Globigerinoides ruber, Globigerina bulloides, Globigerinoides conglobatus and Globigerinita glutinata were collected in Bermuda waters and fixed in a cold cacodylate-buffered 6% glutaraldehyde solution for two hours. They were then rinsed, post-fixed in Palade's fluid, rinsed again and stained with uranyl acetate. This was followed by graded ethanol dehydration, during which they were identified and picked clean of debris. The specimens were finally embedded in Epon 812 by placing each organism in a separate BEEM capsule. After sectioning with a diamond knife, stained sections were viewed in a Philips 200 electron microscope.

The significance of SEM in the diagnosis of haematopoietic malignancies

1978 ◽  
Vol 36 (2) ◽  
pp. 314-315
Author(s):  
Etienne de Harven ◽  
Nina Lampen
Keyword(s):  
Room Temperature ◽  
Culture Medium ◽  
Cell Attachment ◽  
Ethanol Dehydration ◽  
Moist Chamber ◽  
Efficient Alternative ◽  
Mononuclear Leucocytes ◽  
Fast Quenching ◽  
Freeze Dryer ◽  
Scanning Electron

Samples of heparinized blood, or bone marrow aspirates, or cell suspensions prepared from biopsied tissues (nodes, spleen, etc. ) are routinely prepared, after Ficoll-Hypaque concentration of the mononuclear leucocytes, for scanning electron microscopy. One drop of the cell suspension is placed in a moist chamber on a poly-l-lysine pretreated plastic coverslip (Mazia et al., J. Cell Biol. 66:198-199, 1975) and fifteen minutes allowed for cell attachment. Fixation, started in 2. 5% glutaraldehyde in culture medium at room temperature for 30 minutes, is continued in the same fixative at 4°C overnight or longer. Ethanol dehydration is immediately followed by drying at the critical point of CO2 or of Freon 13. An efficient alternative method for ethanol dehydrated cells is to dry the cells at low temperature (-75°C) under vacuum (10-2 Torr) for 30 minutes in an Edwards-Pearse freeze-dryer (de Harven et al., SEM/IITRI/1977, 519-524). This is preceded by fast quenching in supercooled ethanol (between -90 and -100°C).

Elemental analysis of human erythrocytes

1989 ◽  
Vol 47 ◽  
pp. 242-243
Author(s):  
S. A. Livesey ◽  
A. A. del Campo ◽  
E. S. Griffey ◽  
D. Ohlmer ◽  
T. Schifani ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Elemental Analysis ◽  
Human Erythrocyte ◽  
Spectroscopic Analysis ◽  
Model System ◽  
Human Erythrocytes ◽  
List Type ◽  
Chemical Fixation ◽  
Ethanol Dehydration ◽  
Lowicryl K4m

The aim of this study is to compare methods of sample preparation for elemental analysis. The model system which is used is the human erythrocyte. Energy dispersive spectroscopic analysis has been previously reported for cryofixed and cryosectioned erythrocytes. Such work represents the reference point for this study. The use of plastic embedded samples for elemental analysis has also been documented. The work which is presented here is based on human erythrocytes which have been either chemically fixed and embedded or cryofixed and subsequently processed by a variety of techniques which culminated in plastic embedded samples.Heparinized and washed erythrocytes were prepared by the following methods for this study :(1). Chemical fixation in 4% paraformaldehyde/0.25% glutaraldehyde/0.2 M sucrose in 0.1 M Na cacodylate, pH 7.3 for 30 min, followed by ethanol dehydration, infiltration and embedding in Lowicryl K4M at -20° C.

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