Browse
Submit Data
Databases
API
Help

Dataset Information

22 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Heterogeneous Catalytic Oxidation of Ammonia by Various Transition Metals.

ABSTRACT: A well-known demonstration is adapted to simplify the illustration of heterogeneous catalytic oxidation of ammonia. Various metal catalyst wires are placed above the liquid level in a flask containing concentrated ammonia. After brief preheating, some metal wires continue to glow, providing visual evidence of an overall exothermic reaction taking place at the catalyst surface. Thermal heating by a butane flame prior to insertion and in situ resistive heating using a power supply yield identical results. Active catalysts are the group 9 and 10 elements Rh, Ir, Pd, and Pt. Besides the illustration of the Sabatier principle, the effect of the ammonia-to-oxygen ratio can also be visualized, and active metals vary in the production of a grayish smoke. These observations provide a starting point to discuss catalytic selectivity, a topic of great relevance to industrial catalytic oxidation of ammonia.

SUBMITTER: Laan PCM

PROVIDER: S-EPMC6791287 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Heterogeneous Catalytic Oxidation of Ammonia by Various Transition Metals.

Laan Petrus C M PCM Franke Mareena C MC van Lent Richard R Juurlink Ludo B F LBF

Journal of chemical education 20190731 10

A well-known demonstration is adapted to simplify the illustration of heterogeneous catalytic oxidation of ammonia. Various metal catalyst wires are placed above the liquid level in a flask containing concentrated ammonia. After brief preheating, some metal wires continue to glow, providing visual evidence of an overall exothermic reaction taking place at the catalyst surface. Thermal heating by a butane flame prior to insertion and <i>in situ</i> resistive heating using a power supply yield ide ...[more]

PMID: 31624412

Similar Datasets

Heterogeneous Catalytic Oxidation of Amides to Imides by Manganese Oxides.

Project description:Herein, we report a one-step peroxide mediated heterogeneous catalytic oxidation of amides to imides utilizing a series of manganese oxides. Among them, Cs/Mn2O3 was found to be the most active catalyst for the selective partial oxidation of N-benzylbenzamide to diphenyl imide. We have been able to apply an optimized oxidation method to other aromatic substrates. The feasibility of using air as an oxidant, the heterogeneous nature, inexpensive catalytic materials, respectable turnover numbers, and chemoselectivity to imides make this methodology an attractive choice for functional group transformations of amides to imides.

| S-EPMC6134084 | biostudies-literature

Catalytic Oxidation of Ammonia over Cerium-Modified Copper Aluminium Zinc Mixed Oxides.

Project description:Copper-containing mixed metal oxides are one of the most promising catalysts of selective catalytic oxidation of ammonia. These materials are characterized by high catalytic efficiency; however, process selectivity to dinitrogen is still an open challenge. The set of Cu-Zn-Al-O and Ce/Cu-Zn-Al-O mixed metal oxides were tested as catalysts of selective catalytic oxidation of ammonia. At the low-temperature range, from 250 °C up to 350 °C, materials show high catalytic activity and relatively high selectivity to dinitrogen. Samples with the highest Cu loading 12 and 15 mol.% of total cation content were found to be the most active materials. Additional sample modification by wet impregnation of cerium (8 wt.%) improves catalytic efficiency, especially N2 selectivity. The comparison of catalytic tests with results of physicochemical characterization allows connecting the catalysts efficiency with the form and distribution of CuO on the samples' surface. The bulk-like well-developed phases were associated with sample activity, while the dispersed CuO phases with dinitrogen selectivity. Material characterization included phase composition analysis (X-ray powder diffraction, UV-Vis diffuse reflectance spectroscopy), determination of textural properties (low-temperature N2 sorption, scanning electron microscopy) and sample reducibility analysis (H2 temperature-programmed reduction).

| S-EPMC8585330 | biostudies-literature

Heterogeneous-Driven Glutathione Oxidation: Defining the Catalytic Role of Chalcopyrite Nanoparticles.

Project description:Transition-metal nanocatalysis represents a novel alternative currently experiencing flourishing progress to tackle the tumor microenvironment (TME) in cancer therapy. These nanomaterials aim at attacking tumor cells using the intrinsic selectivity of inorganic catalysts. In addition, special attention to tune and control the release of these transition metals is also required. Understanding the chemical reactions behind the catalytic action of the transition-metal nanocatalysts and preventing potential undesired side reactions caused by acute cytotoxicity of the released ionic species represent another important field of research. Specifically, copper-based oxides may suffer from acute leaching that potentially may induce toxicity not only to target cancer cells but also to nearby cells and tissues. In this work, we propose the synthesis of chalcopyrite (CuFeS2) nanostructures capable of triggering two key reactions for an effective chemodynamic therapy (CDT) in the heterogeneous phase: (i) glutathione (GSH) oxidation and (ii) oxidation of organic substrates using H2O2, with negligible leaching of metals under TME-like conditions. This represents an appealing alternative toward the development of safer copper-iron-based nanocatalytic materials with an active catalytic response without incurring leaching side phenomena.

| S-EPMC10388351 | biostudies-literature

Differential Responses of the Catalytic Efficiency of Ammonia and Nitrite Oxidation to Changes in Temperature.

Project description:Microbially mediated nitrification plays an important role in the nitrogen (N) cycle, and rates of activity have been shown to change significantly with temperature. Despite this, the substrate affinities of nitrifying bacteria and archaea have not been comprehensively measured and are often assumed to be static in mathematical models of environmental systems. In this study, we measured the oxidation kinetics of ammonia- (NH3) oxidizing archaea (AOA), NH3-oxidizing bacteria (AOB), and two distinct groups of nitrite (NO2 -)-oxidizing bacteria (NOB), of the genera Nitrobacter and Nitrospira, by measuring the maximum rates of apparent activity (V max(app)), the apparent half-saturation constant (K m(app)), and the overall catalytic efficiency (V max(app) /K m(app)) over a range of temperatures. Changes in V max(app) and K m(app) with temperature were different between groups, with V max(app) and catalytic efficiency increasing with temperature in AOA, while V max(app) , K m(app), and catalytic efficiency increased in AOB. In Nitrobacter NOB, V max(app) and K m(app) increased, but catalytic efficiency decreased significantly with temperature. Nitrospira NOB were variable, but V max(app) increased while catalytic efficiency and K m(app) remained relatively unchanged. Michaelis-Menten (MM) and Haldane (H) kinetic models of NH3 oxidation and NO2 - oxidation based on the collected data correctly predict nitrification potential in some soil incubation experiments, but not others. Despite previous observations of coupled nitrification in many natural systems, our results demonstrate significant differences in response to temperature strategies between the different groups of nitrifiers; and indicate the need to further investigate the response of nitrifiers to environmental changes.

| S-EPMC9127996 | biostudies-literature

Heterogeneous Electrochemical Ammonia Oxidation with a Ru-bda Oligomer Anchored on Graphitic Electrodes via CH-π Interactions.

Project description:Molecular catalysts can promote ammonia oxidation, providing mechanistic insights into the electrochemical N2 cycle for a carbon-free fuel economy. We report the ammonia oxidation activity of carbon anodes functionalized with the oligomer {[RuII(bda-κ-N 2 O 2)(4,4'-bpy)]10(4,4'-bpy)}, Rubda-10, where bda is [2,2'-bipyridine]-6,6'-dicarboxylate and 4,4'-bpy is 4,4'-bipyridine. Electrocatalytic studies in propylene carbonate demonstrate that the Ru-based hybrid anode used in a 3-electrode configuration transforms NH3 to N2 and H2 in a 1:3 ratio with near-unity faradaic efficiency at an applied potential of 0.1 V vs Fc+/0, reaching turnover numbers of 7500. X-ray absorption spectroscopic analysis after bulk electrolysis confirms the molecular integrity of the catalyst. Based on computational studies together with electrochemical evidence, ammonia nucleophilic attack is proposed as the primary pathway that leads to critical N-N bond formation.

| S-EPMC9841602 | biostudies-literature

Autotrophic ammonia oxidation by soil thaumarchaea.

Project description:Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, but the relative importance of bacteria and archaea in soil nitrification is unclear and it is believed that soil archaeal ammonia oxidizers may use organic carbon, rather than growing autotrophically. In this soil microcosm study, stable isotope probing was used to demonstrate incorporation of (13)C-enriched carbon dioxide into the genomes of thaumarchaea possessing two functional genes: amoA, encoding a subunit of ammonia monooxygenase that catalyses the first step in ammonia oxidation; and hcd, a key gene in the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle, which has been found so far only in archaea. Nitrification was accompanied by increases in archaeal amoA gene abundance and changes in amoA gene diversity, but no change was observed in bacterial amoA genes. Archaeal, but not bacterial, amoA genes were also detected in (13)C-labeled DNA, demonstrating inorganic CO(2) fixation by archaeal, but not bacterial, ammonia oxidizers. Autotrophic archaeal ammonia oxidation was further supported by coordinate increases in amoA and hcd gene abundance in (13)C-labeled DNA. The results therefore provide direct evidence for a role for archaea in soil ammonia oxidation and demonstrate autotrophic growth of ammonia oxidizing archaea in soil.

| S-EPMC2951460 | biostudies-literature

Depth Distribution of Ammonia Oxidation Rates and Ammonia-Oxidizer Community Composition in the Sargasso Sea

Project description:Ammonia oxidizer community structure were examined in a depth profile from 20 to 2000 m at the Bermuda Atlantic Time-series Study using a functional gene microarray to look at amoA diversity

2012-11-15 | GSE42287 | GEO

Ammonia oxidation microbial environment sample

Project description:Ammonia oxidation microbial environment sample Genome sequencing and assembly

| PRJNA870651 | ENA

Ammonia oxidation at pH 2.5 by a new gammaproteobacterial ammonia-oxidizing bacterium.

Project description:Ammonia oxidation was considered impossible under highly acidic conditions, as the protonation of ammonia leads to decreased substrate availability and formation of toxic nitrogenous compounds. Recently, some studies described archaeal and bacterial ammonia oxidizers growing at pH as low as 4, while environmental studies observed nitrification at even lower pH values. In this work, we report on the discovery, cultivation, and physiological, genomic, and transcriptomic characterization of a novel gammaproteobacterial ammonia-oxidizing bacterium enriched via continuous bioreactor cultivation from an acidic air biofilter that was able to grow and oxidize ammonia at pH 2.5. This microorganism has a chemolithoautotrophic lifestyle, using ammonia as energy source. The observed growth rate on ammonia was 0.196 day-1, with a doubling time of 3.5 days. The strain also displayed ureolytic activity and cultivation with urea as ammonia source resulted in a growth rate of 0.104 day-1 and a doubling time of 6.7 days. A high ammonia affinity (Km(app) = 147 ± 14 nM) and high tolerance to toxic nitric oxide could represent an adaptation to acidic environments. Electron microscopic analysis showed coccoid cell morphology with a large amount of intracytoplasmic membrane stacks, typical of gammaproteobacterial ammonia oxidizers. Furthermore, genome and transcriptome analysis showed the presence and expression of diagnostic genes for nitrifiers (amoCAB, hao, nor, ure, cbbLS), but no nirK was identified. Phylogenetic analysis revealed that this strain belonged to a novel bacterial genus, for which we propose the name "Candidatus Nitrosacidococcus tergens" sp. RJ19.

| S-EPMC8115276 | biostudies-literature

Conductive catalysis by subsurface transition metals.

Project description:The nature of catalysis has been hotly pursued for over a century, and current research is focused on understanding active centers and their electronic structures. Herein, the concept of conductive catalysis is proposed and verified by theoretical simulations and experimental observations. Metallic systems containing buried catalytically active transitional metals and exposed catalytically inert main group metals are constructed, and the electronic interaction between them via metallic bonding is disclosed. Through the electronic interaction, the catalytic properties of subsurface transitional metals (Pd or Rh) can be transferred to outermost main group metals (Al or Mg) for several important transformations like semi-hydrogenation, Suzuki-coupling and hydroformylation. The catalytic force is conductive, in analogy with the magnetic force and electrostatic force. The traditional definition of active centers is challenged by the concept of conductive catalysis and the electronic nature of catalysis is more easily understood. It might provide new opportunities for shielding traditional active centers against poisoning or leaching and allow for precise regulation of their catalytic properties by the conductive layer.

| S-EPMC10849361 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data