scholarly journals Formation of COMs through CO hydrogenation on interstellar grains

2020 ◽  
Vol 634 ◽  
pp. A52 ◽  
Author(s):  
M. A. J. Simons ◽  
T. Lamberts ◽  
H. M. Cuppen
Keyword(s):  
Ethylene Glycol ◽  
Gas Phase ◽  
Low Temperatures ◽  
Interstellar Dust ◽  
Co Hydrogenation ◽  
Methyl Formate ◽  
Kinetic Monte Carlo ◽  
Reaction Network ◽  
Positional Information ◽  
Hydrogenation Reaction

Context. Glycoaldehyde, ethylene glycol, and methyl formate are complex organic molecules that have been observed in dark molecular clouds. Because there is no efficient gas-phase route to produce these species, it is expected that a low-temperature surface route existst that does not require energetic processing. CO hydrogenation experiments at low temperatures showed that this is indeed the case. Glyoxal can form through recombination of two HCO radicals and is then further hydrogenated. Aims. Here we aim to constrain the methyl formate, glycolaldehyde, and ethylene glycol formation on the surface of interstellar dust grains through this cold and dark formation route. We also probe the dependence of the grain mantle composition on the initial gas-phase composition and the dust temperature. Methods. A full CO hydrogenation reaction network was built based on quantum chemical calculations for the rate constants and branching ratios. This network was used in combination with a microscopic kinetic Monte Carlo simulation to simulate ice chemistry, taking into account all positional information. After benchmarking the model against CO-hydrogenation experiments, simulations under molecular cloud conditions were performed. Results. Glycoaldehyde, ethylene glycol, and methyl formate are formed in all interstellar conditions we studied, even at temperatures as low as 8 K. This is because the HCO + HCO reaction can occur when HCO radicals are formed close to each other and do not require to diffuse. Relatively low abundances of methyl formate are formed. The final COM abundances depend more on the H-to-CO ratio and less on temperature. Only above 16 K, where CO build-up is less efficient, does temperature start to play a role. Molecular hydrogen is predominantly formed through abstraction reactions on the surface. The most important reaction leading to methanol is H2CO + CH3O → HCO + CH3OH. Our simulations are in agreement with observed COM ratios for mantles that have been formed at low temperatures.

scholarly journals Mapping observations of complex organic molecules around Sagittarius B2 with the ARO 12 m telescope

2020 ◽  
Vol 492 (1) ◽  
pp. 556-565
Author(s):  
Juan Li ◽  
Junzhi Wang ◽  
Haihua Qiao ◽  
Donghui Quan ◽  
Min Fang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Gas Phase ◽  
Low Temperatures ◽  
Organic Molecules ◽  
Methyl Formate ◽  
Surface Reactions ◽  
High Sensitivity ◽  
Methyl Amine ◽  
Grain Surface ◽  
Complex Organic

ABSTRACT We have performed high-sensitivity mapping observations of several complex organic molecules around Sagittarius B2 with the ARO 12 m telescope at 3 mm wavelength. Based on their spatial distribution, molecules can be classified as either ‘extended’, those detected not only in Sgr B2(N) and Sgr B2(M), or ‘compact’, those only detected toward or near Sgr B2(N) and Sgr B2(M). The ‘extended’ molecules include glycolaldehyde (CH2OHCHO), methyl formate (CH3OCHO), formic acid (t-HCOOH), ethanol (C2H5OH) and methyl amine (CH3NH2), while the ‘compact’ molecules include dimethyl ether (CH3OCH3), ethyl cyanide (C2H5CN), and amino acetonitrile (H2NCH2CN). These ‘compact’ molecules are likely produced under strong UV radiation, while the ‘extended’ molecules are likely formed at low temperatures, via gas-phase or grain-surface reactions. The spatial distribution of ‘warm’ CH2OHCHO at 89 GHz differs from the spatial distribution of ‘cold’ CH2OHCHO observed at 13 GHz. We found evidence for an overabundance of CH2OHCHO compared to that expected from the gas-phase model, which indicates that grain-surface reactions are necessary to explain the origin of CH2OHCHO in Sagittarius B2. Grain-surface reactions are also needed to explain the correlation between the abundances of ‘cold’ CH2OHCHO and C2H5OH. These results demonstrate the importance of grain-surface chemistry in the production of complex organic molecules.

Promotive Selectivity to C2-C3 Polyols From Alkaline Cellulose Hydrogenated by Ionic Liquid-stablized Ru Nanoparticles

2021 ◽  
Author(s):  
Mingrui Liu ◽  
Hua Wang
Keyword(s):  
Ionic Liquid ◽  
Ethylene Glycol ◽  
Conversion Rate ◽  
Metal Salt ◽  
Hydrogenation Reaction ◽  
Metal Catalyst ◽  
Ru Nanoparticles ◽  
Naoh Solution ◽  
Plausible Mechanism ◽  
Amorphous Part

Abstract Alkaline cellulose hydrogenolysis on metal catalyst was an effective way to get C2~C3 polyols. The alkaline cellulose was obtained by treating cellulose with 4 wt% NaOH solution. Ionic liquid-stablized Ru nanoparticles were prepared by reducing metal salt in ionic liquid. The SEM results indicate that the amorphous part of alkaline cellulose is helpful for getting the catalyst into the cavities to have a further hydrogenation reaction. When hydrogenolysis of alkaline cellulose over Ru/[Bmim]BF4 nanoparticles was conducted at 433 K, 63.78% of the substrate was converted with glycerol, 1,2-propanediol and ethylene glycol as main products of which selectivity was up to 58.91 %, whereas the conversion rate over Ru/C catalyst of alkaline cellulose was 59.23 % and only 26.11 % C2~C3 polyols were detected. Moreover, if the ionic liquid-stablized Ru nanoparticles were doped with 53.7 % Ni, the selectivity of C2~C3 polyols was promoted to 65.07 %. These results suggested the advantages of the ionic liquid-stablized Ru nanoparticles, especially doping with Ni, have potentials for promotive selectivity to C2~C3 alcohols. Put forward the plausible mechanism finally.

scholarly journals The formation of the building blocks of peptides on interstellar dust grains

2019 ◽  
Vol 15 (S350) ◽  
pp. 216-219
Author(s):  
N. F. W. Ligterink ◽  
J. Terwisscha van Scheltinga ◽  
V. Kofman ◽  
V. Taquet ◽  
S. Cazaux ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Reaction Network ◽  
Building Blocks ◽  
Dust Grains ◽  
Reaction Products ◽  
Experimental Conditions ◽  
Interstellar Dust Grains ◽  
Temperature Programmed ◽  
Life On Earth ◽  
Emergence Of Life

AbstractThe emergence of life on Earth may have its origin in organic molecules formed in the interstellar medium. Molecules with amide and isocyanate groups resemble structures found in peptides and nucleobases and are necessary for their formation. Their formation is expected to take place in the solid state, on icy dust grains, and is studied here by far-UV irradiating a CH4:HNCO mixture at 20 K in the laboratory. Reaction products are detected by means of infrared spectroscopy and temperature programmed desorption - mass spectrometry. Various simple amides and isocyanates are formed, showing the importance of ice chemistry for their interstellar formation. Constrained by experimental conditions, a reaction network is derived, showing possible formation pathways of these species under interstellar conditions.

Structured Pd–Au/Cu-fiber catalyst for gas-phase hydrogenolysis of dimethyl oxalate to ethylene glycol

2015 ◽  
Vol 51 (52) ◽  
pp. 10547-10550 ◽  
Author(s):  
Li Zhang ◽  
Lupeng Han ◽  
Guofeng Zhao ◽  
Ruijuan Chai ◽  
Qiaofei Zhang ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Gas Phase ◽  
Dimethyl Oxalate

A structured Pd–Au/Cu-fiber with a ternary Pd–Au–Cu+ complex is active, selective and stable for the gas-phase hydrogenolysis of dimethyl oxalate to ethylene glycol.

Simulation of degradation of the organic contaminants ethylene glycol and phenol by iron nanoparticles using the kinetic Monte Carlo method

RSC Advances ◽  
2014 ◽  
Vol 4 (62) ◽  
pp. 32928-32933 ◽  
Author(s):  
Hamed Moradmand Jalali
Keyword(s):  
Hydrogen Peroxide ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Ethylene Glycol ◽  
Organic Contaminants ◽  
Iron Nanoparticles ◽  
Kinetic Monte Carlo ◽  
Kinetic Monte Carlo Method ◽  
System P

We applied kinetic Monte Carlo simulation to study the kinetics and mechanisms of the degradation of the organic pollutants ethylene glycol and phenol by iron(iii) nanoparticles and hydrogen peroxide as the catalytic system.

scholarly journals Formamide reaction network in gas phase and solution via a unified theoretical approach: Toward a reconciliation of different prebiotic scenarios

2015 ◽  
Vol 112 (49) ◽  
pp. 15030-15035 ◽  
Author(s):  
Fabio Pietrucci ◽  
Antonino Marco Saitta
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Reaction Network ◽  
Theoretical Method ◽  
Active Role ◽  
Decomposition Reaction ◽  
Ab Initio Molecular Dynamics ◽  
Collective Variables ◽  
Wide Range ◽  
Reaction Channels

Increasing experimental and theoretical evidence points to formamide as a possible hub in the complex network of prebiotic chemical reactions leading from simple precursors like H2, H2O, N2, NH3, CO, and CO2 to key biological molecules like proteins, nucleic acids, and sugars. We present an in-depth computational study of the formation and decomposition reaction channels of formamide by means of ab initio molecular dynamics. To this aim we introduce a new theoretical method combining the metadynamics sampling scheme with a general purpose topological formulation of collective variables able to track a wide range of different reaction mechanisms. Our approach is flexible enough to discover multiple pathways and intermediates starting from minimal insight on the systems, and it allows passing in a seamless way from reactions in gas phase to reactions in liquid phase, with the solvent active role fully taken into account. We obtain crucial new insight into the interplay of the different formamide reaction channels and into environment effects on pathways and barriers. In particular, our results indicate a similar stability of formamide and hydrogen cyanide in solution as well as their relatively facile interconversion, thus reconciling experiments and theory and, possibly, two different and competing prebiotic scenarios. Moreover, although not explicitly sought, formic acid/ammonium formate is produced as an important formamide decomposition byproduct in solution.

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