scholarly journals Selectivity descriptors for the direct hydrogenation of CO2 to hydrocarbons during zeolite-mediated bifunctional catalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adrian Ramirez ◽  
Xuan Gong ◽  
Mustafa Caglayan ◽  
Stefan-Adrian F. Nastase ◽  
Edy Abou-Hamad ◽  
...  
Keyword(s):  
Large Degree ◽  
Great Promise ◽  
Product Selectivity ◽  
Highly Active ◽  
Cascade Processes ◽  
One Step ◽  
Selectivity Control ◽  
Direct Hydrogenation ◽  
The One ◽  
Hydrogenation Of Co

AbstractCascade processes are gaining momentum in heterogeneous catalysis. The combination of several catalytic solids within one reactor has shown great promise for the one-step valorization of C1-feedstocks. The combination of metal-based catalysts and zeolites in the gas phase hydrogenation of CO2 leads to a large degree of product selectivity control, defined mainly by zeolites. However, a great deal of mechanistic understanding remains unclear: metal-based catalysts usually lead to complex product compositions that may result in unexpected zeolite reactivity. Here we present an in-depth multivariate analysis of the chemistry involved in eight different zeolite topologies when combined with a highly active Fe-based catalyst in the hydrogenation of CO2 to olefins, aromatics, and paraffins. Solid-state NMR spectroscopy and computational analysis demonstrate that the hybrid nature of the active zeolite catalyst and its preferred CO2-derived reaction intermediates (CO/ester/ketone/hydrocarbons, i.e., inorganic-organic supramolecular reactive centers), along with 10 MR-zeolite topology, act as descriptors governing the ultimate product selectivity.

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.

The interlocked in situ fabrication of graphene@prussian blue nanocomposite as high-performance supercapacitor

2018 ◽  
Vol 47 (37) ◽  
pp. 13126-13134 ◽  
Author(s):  
Shi-Cheng Wang ◽  
Minli Gu ◽  
Luqing Pan ◽  
Junfeng Xu ◽  
Lei Han ◽  
...  
Keyword(s):  
Prussian Blue ◽  
High Performance ◽  
Great Promise ◽  
High Quality ◽  
In Situ Fabrication ◽  
Excellent Electrochemical Performance ◽  
One Step ◽  
The One ◽  
Method Show

High-quality graphene@prussian blue (G@PB) nanocomposite sheets fabricated via the one-step in situ hydrothermal method show great promise for energy-storage hybrid electrodes with excellent electrochemical performance.

Insights into the unusual role of chlorine in product selectivity for direct hydrogenation of CO/CO2 to short-chain olefins

2020 ◽  
pp. 127424
Author(s):  
Indrajit K. Ghosh ◽  
Zafar Iqbal ◽  
Tracey van Heerden ◽  
Eric van Steen ◽  
Ankur Bordoloi
Keyword(s):  
Short Chain ◽  
Product Selectivity ◽  
Direct Hydrogenation ◽  
Hydrogenation Of Co

Carbon nitride supported AgPd alloy nanocatalysts for dehydrogenation of formic acid under visible light

2017 ◽  
Vol 5 (14) ◽  
pp. 6382-6387 ◽  
Author(s):  
Liping Xiao ◽  
Young-Si Jun ◽  
Binghui Wu ◽  
Deyu Liu ◽  
Tracy T Chuong ◽  
...  
Keyword(s):  
Formic Acid ◽  
Visible Light ◽  
Carbon Nitride ◽  
Room Temperature ◽  
Ambient Condition ◽  
Alloy Nanoparticles ◽  
Highly Active ◽  
One Step ◽  
The One ◽  
Temperature Preparation

We report a facile approach for the one-step room-temperature preparation of nearly monodisperse AgPd alloy nanoparticles supported on semiconductor graphitic carbon nitride (g-CN). The AgPd/g-CN nanocatalysts are highly active and durable for dehydrogenation of formic acid under visible light or dark at ambient condition.

scholarly journals Easy and Rapid Purification of Highly Active Nisin

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
André Abts ◽  
Antonino Mavaro ◽  
Jan Stindt ◽  
Patrick J. Bakkes ◽  
Sabine Metzger ◽  
...  
Keyword(s):  
Low Ph ◽  
Exchange Chromatography ◽  
Single Step ◽  
Cation Exchange Chromatography ◽  
Gram Positive Bacteria ◽  
Highly Active ◽  
One Step ◽  
Rapid Purification ◽  
The One ◽  
Purification Protocol

Nisin is an antimicrobial peptide produced and secreted by several L. lactis strains and is specifically active against Gram-positive bacteria. In previous studies, nisin was purified via cation exchange chromatography at low pH employing a single-step elution using 1 M NaCl. Here, we describe an optimized purification protocol using a five-step NaCl elution to remove contaminants. The obtained nisin is devoid of impurities and shows high bactericidal activity against the nisin-sensitive L. lactis strain NZ9000. Purified nisin exhibits an IC50 of ~3 nM, which is a tenfold improvement as compared to nisin obtained via the one-step elution procedure.

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

2020 ◽  
Vol 24 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Zita Rádai ◽  
Réka Szabó ◽  
Áron Szigetvári ◽  
Nóra Zsuzsa Kiss ◽  
Zoltán Mucsi ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Room Temperature ◽  
Phase Transfer ◽  
One Pot ◽  
Substrate Dependence ◽  
Triethylbenzylammonium Chloride ◽  
One Step ◽  
The Pudovik Reaction ◽  
The One ◽  
Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

Calorimetric Sensor for Ethanol Using Ni2+-nitrilotriacetic Acid (NTA) Resin Immobilized Alcohol Dehydrogenase (ADH)

2020 ◽  
Vol 16 (6) ◽  
pp. 795-799
Author(s):  
YongJin Li
Keyword(s):  
Cost Effective ◽  
Nitrilotriacetic Acid ◽  
Repeated Measurements ◽  
Great Promise ◽  
Calorimetric Sensor ◽  
Controlled Pore Glass ◽  
Pore Glass ◽  
One Step ◽  
Immobilization Matrix ◽  
Enzyme Thermistor

Background: A simple, fast and economic analytical method for the determination of ethanol is important for clinical, biological, forensic and physico-legal purposes. Methods: Ni2+-NTA resin was used as an immobilization matrix for the simple one-step purification/ immobilization of his6-tagged ADH. Different alcohols with a concentration range of 0.5-50% V/V, namely methanol, ethanol and propanol were measured using prepared ADH enzyme thermistor. The ethanol content of Tsingtao beer was tested as a real sample containing alcohol. Reproducibility and stability of prepared ADH enzyme thermistor were also investigated by repeated measurements. Results: In comparison to the controlled pore glass (a common used support for the immobilization of enzyme) used in thermal biosensor, the use of Ni2+-NTA resin not only led to simple one-step purification/ immobilization by his6-tagged ADH binding to Ni2+-NTA resin, but also made the immobilizing supports reusable. The prepared biosensor can be used to determine ethanol and methanol by the calorimetric measurement. A linear range of 1 -32% (V/V) and 2-20% (V/V) was observed for ethanol and methanol, respectively. The detection limits were 0.3% (V/V) and 1% (V/V) for ethanol and methanol, respectively. The tested ethanol concentration of Tsingtao beer was 4.5% V/V, which is comparable with the labeled alcohol by volume (ABV) 4.80%. Conclusion: Ni2+-NTA resin, as an immobilization matrix in ET sensor, provides a simple one-step purification/immobilization for His6-tagged recombinase and a reusable immobilization matrix. The prepared biosensor exhibits good repeatability and stability. Such a new biosensor shows great promise for rapid, simple, and cost-effective analysis of ethanol and methanol, both in qualitative and in quantitative tests.

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