One step synthesis of highly active and selective epoxidation catalysts formed by organic–inorganic Ti containing mesoporous composites

1998 ◽  
pp. 1899-1900 ◽  
Author(s):  
Avelino Corma ◽  
Maria T. Navarro ◽  
Fernando Rey
Keyword(s):  
Highly Active ◽  
One Step ◽  
Mesoporous Composites

scholarly journals Improving the Activity of Fe/C/N ORR Electrocatalyst Using Double Ammonia Promoted CO2 Laser Pyrolysis

2020 ◽  
Vol 6 (4) ◽  
pp. 63
Author(s):  
Henri Perez ◽  
Mathieu Frégnaux ◽  
Emeline Charon ◽  
Arnaud Etcheberry ◽  
Olivier Sublemontier
Keyword(s):  
Co2 Laser ◽  
Large Scale ◽  
Laser Energy ◽  
Reduction Reaction ◽  
Laser Pyrolysis ◽  
Highly Active ◽  
One Step ◽  
Orr Activity ◽  
Set Up ◽  
The One

Recently, we reported the use of CO2 laser pyrolysis for the synthesis of promising Fe/C/N electrocatalysts for Oxygen Reduction Reaction (ORR) in fuel cells. The set-up used single laser pyrolysis of an aerosolized solution of iron acetylacetonate in toluene with ammonia, both as laser energy transfer agent and nitrogen source. In the present paper, we investigate the effect of a second ammonia promoted CO2 laser pyrolysis on the feature and ORR activity of Fe/C/N electrocatalysts. Indeed, compared to single pyrolysis, the second ammonia promoted CO2 laser pyrolysis could be an interesting way to synthesize in one-step performing ORR electrocatalysts on a large scale. For this comparison, a two-stage reactor was built, allowing both single ammonia-induced CO2 laser pyrolysis as reported previously or double ammonia-induced CO2 laser pyrolysis. In the latter configuration, the catalyst nanopowder flow is formed at the first stage of the reactor, then mixed with a second ammonia flow and allowed to cross a second CO2 laser beam, thus undergoing a second ammonia-induced CO2 laser pyrolysis before being collected on filters. It is found that the second ammonia-induced CO2 laser pyrolysis significantly improves the ORR performances of the materials prepared by single CO2 laser pyrolysis. The effect is demonstrated for three different catalysts for which the onset potentials for the ORR from single-stage to double-stage configuration increase from 625 mV to 845 mV, 790 mV to 860 mV, and 800 mV to 885 mV, respectively. The selectivity of the ORR was determined at 600 mV/SHE and lie between 3.41 and 3.72. These promising performances suggesting potentialities for the one-step formation of highly active Fe/C/N ORR electrocatalysts are discussed, based on results of surface analysis by XPS, specific surface area measurements, and Raman spectroscopy.

scholarly journals Characterization of highly active 2-keto-3-deoxy-L-arabinonate and 2-keto-3-deoxy-D-xylonate dehydratases in terms of the biotransformation of hemicellulose sugars to chemicals

2020 ◽  
Vol 104 (16) ◽  
pp. 7023-7035
Author(s):  
Samuel Sutiono ◽  
Bettina Siebers ◽  
Volker Sieber
Keyword(s):  
Racemic Mixture ◽  
Highly Active ◽  
Key Points ◽  
Deoxy Sugar ◽  
Weimberg Pathway ◽  
One Step ◽  
The One ◽  
Increased Activity ◽  
Enzyme Class

Abstract2-keto-3-L-arabinonate dehydratase (L-KdpD) and 2-keto-3-D-xylonate dehydratase (D-KdpD) are the third enzymes in the Weimberg pathway catalyzing the dehydration of respective 2-keto-3-deoxy sugar acids (KDP) to α-ketoglutaric semialdehyde (KGSA). The Weimberg pathway has been explored recently with respect to the synthesis of chemicals from L-arabinose and D-xylose. However, only limited work has been done toward characterizing these two enzymes. In this work, several new L-KdpDs and D-KdpDs were cloned and heterologously expressed in Escherichia coli. Following kinetic characterizations and kinetic stability studies, the L-KdpD from Cupriavidus necator (CnL-KdpD) and D-KdpD from Pseudomonas putida (PpD-KdpD) appeared to be the most promising variants from each enzyme class. Magnesium had no effect on CnL-KdpD, whereas increased activity and stability were observed for PpD-KdpD in the presence of Mg2+. Furthermore, CnL-KdpD was not inhibited in the presence of L-arabinose and L-arabinonate, whereas PpD-KdpD was inhibited with D-xylonate (I50 of 75 mM), but not with D-xylose. Both enzymes were shown to be highly active in the one-step conversions of L-KDP and D-KDP. CnL-KdpD converted > 95% of 500 mM L-KDP to KGSA in the first 2 h while PpD-KdpD converted > 90% of 500 mM D-KDP after 4 h. Both enzymes in combination were able to convert 83% of a racemic mixture of D,L-KDP (500 mM) after 4 h, with both enzymes being specific toward the respective stereoisomer. Key points• L-KdpDs and D-KdpDs are specific toward L- and D-KDP, respectively.• Mg2+affected activity and stabilities of D-KdpDs, but not of L-KdpDs.• CnL-KdpD and PpD-KdpD converted 0.5 M of each KDP isomer reaching 95 and 90% yield.• Both enzymes in combination converted 0.5 M racemic D,L-KDP reaching 83% yield.

Enhanced oxygen evolution on visible light responsive TaON photocatalysts co-loaded with highly active Ru species for IO3− reduction and Co species for water oxidation

2017 ◽  
Vol 1 (4) ◽  
pp. 748-754 ◽  
Author(s):  
Yukari Iwase ◽  
Osamu Tomita ◽  
Masanobu Higashi ◽  
Ryu Abe
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Water Oxidation ◽  
Redox Couple ◽  
Highly Active ◽  
One Step ◽  
Type Water ◽  
Ru Species

Loading an appropriate cocatalyst significantly enhances the activity of semiconductor photocatalysts in both conventional one-step water splitting and Z-scheme-type water splitting with a redox couple.

scholarly journals One-step isolation and biochemical characterization of a highly active plant PSII monomeric core

2011 ◽  
Vol 108 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Cristina Pagliano ◽  
Fabiana Chimirri ◽  
Guido Saracco ◽  
Francesco Marsano ◽  
James Barber
Keyword(s):  
Biochemical Characterization ◽  
Highly Active ◽  
One Step

One-step synthesis of trimetallic Pt–Pd–Ru nanodendrites as highly active electrocatalysts

RSC Advances ◽  
2015 ◽  
Vol 5 (39) ◽  
pp. 31147-31152 ◽  
Author(s):  
Kamel Eid ◽  
Victor Malgras ◽  
Pei He ◽  
Kunmiao Wang ◽  
Ali Aldalbahi ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Methanol Oxidation ◽  
Oxidation Reaction ◽  
Reduction Reaction ◽  
Methanol Oxidation Reaction ◽  
Highly Active ◽  
One Step

Trimetallic Pt–Pd–Ru nanodendrites synthesized by a one-step route are highly active electrocatalysts for methanol oxidation reaction and oxygen reduction reaction.

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