Pulse dynamic measurements of oxygen chemisorption on sulphided Co-Mo/Al2O3 catalyst – Effect of experimental conditions

1987 ◽  
Vol 52 (8) ◽  
pp. 1905-1914 ◽  
Author(s):  
Hana Zahradníková ◽  
Ludvík Beránek
Keyword(s):  
Inert Gas ◽  
Effect Of Temperature ◽  
Dynamic Measurements ◽  
Experimental Conditions ◽  
Oxygen Chemisorption ◽  
Time Regime ◽  
Catalyst Effect ◽  
Al2o3 Catalyst

The effect of temperature and time regime of individual steps of the methodic procedure (i.e. catalyst drying, sulphidation, purification of the sulphided surface by inert gas, and chemisorption) on pulse dynamic measurements of oxygen chemisorption of commercial sulphided Co-Mo/Al2O3 catalyst have been studied. The strongest effect was exerted by the chemisorption temperature and by the temperature and time of purification of the surface of sulphided catalyst. Optimum experimental conditions for testing catalysts of this type by the described chemisorption method are proposed.

Chemisorption of oxygen and hydrogenation of ethylene on sulphided Co-Mo/Al2O3 catalyst. Effect of activation process

1989 ◽  
Vol 54 (8) ◽  
pp. 2069-2082 ◽  
Author(s):  
Hana Zahradníková ◽  
Ludvík Beránek
Keyword(s):  
Active Sites ◽  
Room Temperature ◽  
Dynamic Method ◽  
Activation Process ◽  
Subsequent Reduction ◽  
Oxygen Chemisorption ◽  
Hydrogenation Reactions ◽  
Catalyst Effect ◽  
Al2o3 Catalyst ◽  
Hydrogenation Of Ethylene

Oxygen chemisorption by pulse dynamic method at room temperature and the activity for ethylene hydrogenation at 300 °C in a flow regime were determined for Co-Mo/Al2O3 catalyst CHEROX 36-01 sulphided by a H2S/H2 (1:10) mixture at 400 °C. The measurements were carried out either immediately after sulphidation or after subsequent reduction of the sulphided catalyst by hydrogen. The chemisorption of oxygen was measured both prior to and after the catalytic reaction. In addition, the reactivation of the catalyst was examined after its passivation by oxygen chemisorption. The reactivation was effected either by resulphidation or by reduction with hydrogen at 400 °C, on repeated reactivation also by combination of both procedures, variables being the time of activation and reactivation steps. The results are discussed from the standpoint of the structure and interrelation between active sites for oxygen chemisorption and catalytic, especially hydrogenation reactions. Formation of coordinately unsaturated sites and SH groups is emphasized. The reasons of possible failures in correlations between chemisorption capacity for oxygen and catalytic activity are mentioned.

Applicability of Instability Index for In vitro Protein Stability Prediction

2019 ◽  
Vol 26 (5) ◽  
pp. 339-347 ◽  
Author(s):  
Dilani G. Gamage ◽  
Ajith Gunaratne ◽  
Gopal R. Periyannan ◽  
Timothy G. Russell
Keyword(s):  
Protein Stability ◽  
Caulobacter Crescentus ◽  
Effect Of Temperature ◽  
Instability Index ◽  
Dipeptide Composition ◽  
Experimental Conditions ◽  
The Stability ◽  
Vitro Protein

Background: The dipeptide composition-based Instability Index (II) is one of the protein primary structure-dependent methods available for in vivo protein stability predictions. As per this method, proteins with II value below 40 are stable proteins. Intracellular protein stability principles guided the original development of the II method. However, the use of the II method for in vitro protein stability predictions raises questions about the validity of applying the II method under experimental conditions that are different from the in vivo setting. Objective: The aim of this study is to experimentally test the validity of the use of II as an in vitro protein stability predictor. Methods: A representative protein CCM (CCM - Caulobacter crescentus metalloprotein) that rapidly degrades under in vitro conditions was used to probe the dipeptide sequence-dependent degradation properties of CCM by generating CCM mutants to represent stable and unstable II values. A comparative degradation analysis was carried out under in vitro conditions using wildtype CCM, CCM mutants and two other candidate proteins: metallo-β-lactamase L1 and α -S1- casein representing stable, borderline stable/unstable, and unstable proteins as per the II predictions. The effect of temperature and a protein stabilizing agent on CCM degradation was also tested. Results: Data support the dipeptide composition-dependent protein stability/instability in wt-CCM and mutants as predicted by the II method under in vitro conditions. However, the II failed to accurately represent the stability of other tested proteins. Data indicate the influence of protein environmental factors on the autoproteolysis of proteins. Conclusion: Broader application of the II method for the prediction of protein stability under in vitro conditions is questionable as the stability of the protein may be dependent not only on the intrinsic nature of the protein but also on the conditions of the protein milieu.

scholarly journals Effect of temperature on acid hydrolysis of Jerusalem artichoke as raw material for ethanol production

2013 ◽  
pp. 279-287 ◽  
Author(s):  
Radojka Razmovski ◽  
Vesna Vucurovic ◽  
Uros Miljic ◽  
Vladimir Puskas
Keyword(s):  
Hold Time ◽  
Jerusalem Artichoke ◽  
Raw Material ◽  
Effect Of Temperature ◽  
Industrial Biotechnology ◽  
Microbial Conversion ◽  
Experimental Conditions ◽  
Theoretical Yield ◽  
Renewable Raw Material ◽  
Layer Chromatography

Jerusalem artichoke (JA) is a low-requirement crop, which does not interfere with food chain, and is a promising carbon source for industrial fermentation. Microbial conversion of such a renewable raw material to useful products, such as ethanol, is an important objective in industrial biotechnology. In this study, ethanol was efficiently produced from the hydrolyzates of JA obtained at different pH values (pH 2.5, pH 3.0 and pH 3.5), temperature (120, 130, 132 and 134?C) and hold time (30 and 60 min) by Saccharomyces cerevisiae. The efficient degradation of JA by HCl under certain experimental conditions was confirmed by thin-layer chromatography. Ethanol concentration of 7.52% (w/w), which corresponds to 93.89 % of the theoretical yield is achieved by ethanol fermentation of JA hydrolyzate obtained at pH 2.5.

The effects of temperature and pH on the embryonic development of two species of Triturus (Caudata: Salamandridae)

2007 ◽  
Vol 28 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Leonardo Vignoli ◽  
Marco Bologna ◽  
Manuela D'Amen
Keyword(s):  
Mortality Rate ◽  
Embryonic Development ◽  
Effect Of Temperature ◽  
Acidic Ph ◽  
Larval Life ◽  
Experimental Conditions ◽  
Rate Of Development ◽  
Constant Ph ◽  
Effects Of Temperature ◽  
Increasing Temperature

AbstractAmphibian populations are especially sensitive to aquatic parameters, in particular during embryonic and larval life. Our aim was to test for an effect of temperature (T = 13°C, 20°C and 25°C at constant pH = 7) and pH (pH = 5.5, 7 and 8.5 at constant T= 20°C) on embryos of two species of Triturus, T. carnifex carnifex and T. italicus (Amphibia, Salamandridae) using GLM procedure. Trend of embryogenesis processes, time to hatching and rate of development have a similar effect in both species in the used range of temperature and pH. Time to hatching decreased significantly with the increasing temperature. The pH experimental conditions had no effect on T. carnifex embryos survival, while the acidic pH condition raised the mortality rate in T. italicus, whose embryos should be more vulnerable than those of T. carnifex to acidification in nature.

scholarly journals Hydrogenation of Acetic Acid Over PtSn/Al2O3 Catalyst: Effect of Shaping Method, Kinetics and Stability

2015 ◽  
Vol 27 (4) ◽  
pp. 1293-1298 ◽  
Author(s):  
Ke Zhang ◽  
Haitao Zhang ◽  
Hongfang Ma ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Acetic Acid ◽  
Catalyst Effect ◽  
Al2o3 Catalyst

Two-Dimensional Attenuated Total Reflection Infrared and Near-Infrared Correlation Study of the Structure of Butyl Alcohol/Water Mixtures

2007 ◽  
Vol 61 (9) ◽  
pp. 928-934 ◽  
Author(s):  
Dagmara Wojtków ◽  
Mirosław A. Czarnecki
Keyword(s):  
Near Infrared ◽  
Correlation Study ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Effect Of Temperature ◽  
Two Dimensional ◽  
Experimental Conditions ◽  
Oh Groups ◽  
Alcohol Water ◽  
Anharmonicity Constants

The effect of temperature on attenuated total reflection infrared (ATR-IR) and near-infrared (NIR) transmission spectra of pure butan-1-ol, butan-2-ol, 2-methyl-propan-1-ol, 2-methyl-propan-2-ol, and mixtures with a small water content (XH2O ≤ 0.1) have been examined. The spectra were analyzed using a two-dimensional (2D) correlation approach. Two kinds of correlation analysis were performed: IR–IR and NIR–NIR homo-correlation and IR–NIR hetero-correlation. Our results reveal that the addition of small to moderate amounts of water does not destroy the structure of alcohol. The presence of water stabilizes the structure of alcohols and this effect is more evident for sec-butanol and tert-butanol. The ATR-IR spectra provide information on the most associated species, whereas absorption of the smaller associates and the free OH group is hardly seen. On the contrary, in the NIR spectra the absorption of the free OH groups dominates. The ability of resolution enhancement in the hetero-correlation asynchronous spectra is reduced as compared to that in the homo-correlation spectra. On the other hand, peaks may appear in the hetero-correlation synchronous spectra that are not observed in the homo-correlation contour plots. The positions of the synchronous peaks were used for evaluation of anharmonicity constants. These values for the free OH group do not depend on the experimental conditions. In contrast, the anharmonicity constants for the bonded OH groups determined from the spectra of pure alcohols may significantly differ from those obtained from diluted solutions.

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