Xn:Harmful;94977-27-2Relevant academic research and scientific papers
Catalyst for melamine production
Moiseeva,Kurylev,Pomerantsev,Tubolkin
, p. 1883 - 1884 (2002)
A novel electrolytic method for preparing the catalyst (active aluminum oxide) for melamine synthesis and a process for catalytic synthesis of melamine from urea are proposed.
Solvent dependent structures of melamine: Porous or nonporous?
Li, Peng,Arman, Hadi D.,Wang, Hailong,Weng, Linhong,Alfooty, Khalid,Angawi, Rehab F.,Chen, Banglin
, p. 1871 - 1875 (2015)
Two hydrogen-bonded organic frameworks (HOFs) of the melamine (MA), MA-1-H2O and MA-2-DMF, have been crystallized in H2O and DMF (N,N-Dimethylformamide), respectively. Structurally, MA-1-H2O and MA-2-DMF are condensed and
Dicyandiamide preparation method
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Paragraph 0022-0025; 0028-0030; 0033-0035; 0038-0040; 0043-, (2021/01/24)
The invention provides a dicyandiamide preparation method, which comprises: mixing lime nitrogen and water to carry out a hydrolysis reaction, and introducing carbon dioxide to carry out a decalcification reaction to obtain calcium carbonate and a cyanamide aqueous solution; filtering the cyanamide aqueous solution, and filtering out particles to obtain a pure cyanamide aqueous solution; heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution; and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamidecrystals. By adopting the method, impurities such as calcium oxide, calcium hydroxide and calcium carbonate in dicyandiamide are removed, and the quality of a dicyandiamide product is improved.
A Facile Synthesis of Pd–C3N4@Titanate Nanotube Catalyst: Highly Efficient in Mizoroki–Heck, Suzuki–Miyaura C–C Couplings
Velpula, Venkata Ramana Kumar,Ketike, Thirupathaiah,Paleti, Gidyonu,Kamaraju, Seetha Rama Rao,Burri, David Raju
, p. 95 - 105 (2019/11/03)
Abstract: A Pd–C3N4@titanate nanotube (Pd–C3N4@TNT) catalyst workable in water medium, robust against leaching and agglomeration was prepared in a facile synthetic procedure using quite common chemicals such as TiO2 powder, urea and palladium acetate. The Pd–C3N4@TNT catalyst has been characterized by BET surface area and pore size distribution, X-ray diffraction, solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The Pd–C3N4@TNT is a green catalyst for the Miziroki–Heck and Suzuki–Miyaura C–C coupling reactions in water medium with high efficiency (??99% product yields) due to atomic level immobilization of Pd in C3N4 networked titanate nanotubes. Pd–C3N4@TNT is robust against leaching and agglomeration due to stable and furthermore it is recyclable and usable at least for five repeated cycles. The use of water as solvent, absence of leaching and agglomeration, recyclability and reusability ascertains the greenness of Pd–C3N4@TNT) catalyst and process. Graphic Abstract: Novel Pd–C3N4@titanate nanotube catalyst prepared from bulk TiO2 and urea by simple hydrothermal and thermal pyrolysis followed by immobilization of Pd is active and selective for Mizoroki–Heck, Suzuki–Miyaura C–C couplings in water medium.[Figure not available: see fulltext.].
LOW-ENERGY CONSUMPTION PROCESS WITH REDUCED AMMONIA CONSUMPTION, FOR THE PRODUCTION OF HIGH-PURITY MELAMINE THROUGH THE PYROLYSIS OF UREA, AND RELATIVE PLANT
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Paragraph 0103-0123, (2020/02/13)
A process is described, having a low-energy consumption and reduced ammonia consumption for the production of high-purity melamine, through the pyrolysis of urea, and the relative plant.
Prebiotic Origin of Pre-RNA Building Blocks in a Urea “Warm Little Pond” Scenario
Menor Salván,Bouza, Marcos,Fialho, David M.,Burcar, Bradley T.,Fernández, Facundo M.,Hud, Nicholas V.
, p. 3504 - 3510 (2020/10/02)
Urea appears to be a key intermediate of important prebiotic synthetic pathways. Concentrated pools of urea likely existed on the surface of the early Earth, as urea is synthesized in significant quantities from hydrogen cyanide or cyanamide (widely accepted prebiotic molecules), it has extremely high water solubility, and it can concentrate to form eutectics from aqueous solutions. We propose a model for the origin of a variety of canonical and non-canonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs.The dual nucleophilic-electrophilic character of urea makes it an ideal precursor for the formation of nitrogenous heterocycles. We propose a model for the origin of a variety of canonical and noncanonical nucleobases, including some known to form supramolecular assemblies that contain Watson-Crick-like base pairs. These reactions involve urea condensation with other prebiotic molecules (e. g., malonic acid) that could be driven by environmental cycles (e. g., freezing/thawing, drying/wetting). The resulting heterocycle assemblies are compatible with the formation of nucleosides and, possibly, the chemical evolution of molecular precursors to RNA. We show that urea eutectics at moderate temperature represent a robust prebiotic source of nitrogenous heterocycles. The simplicity of these pathways, and their independence from specific or rare geological events, support the idea of urea being of fundamental importance to the prebiotic chemistry that gave rise to life on Earth.
Promoting condensation kinetics of polymeric carbon nitride for enhanced photocatalytic activities
Ni, Dongya,Zhang, Yuye,Shen, Yanfei,Liu, Songqin,Zhang, Yuanjian
, (2019/05/29)
Polymeric carbon nitride (CN) semiconductor by thermal condensation of N-rich precursors has attracted much attention for its capability ranging from photocatalytic and photoelectrochemical energy conversion to biosensing. However, the influence of condensation process on the final structure of CN was rarely studied, making the condensation kinetic far from be fully optimized. Herein, we report the preparation of CN by a simple condensation kinetics modulation using a faster ramping rate during the polymerization process. The modified condensation recipe was even simpler than the conventional one, but led to an improved photocatalytic H2 evolution up to 3 times without any additional chemicals or other complements. Detailed mechanism studies revealed the increase of crystallinity and surface area due to the rapid condensation played the key roles. This work would offer a more facile and effective way to prepare bulk CN for large-scale industrial applications of bulk CN with higher photocatalytic actives for sustainable energy, environmental and biosensing.
Dramatic visible photocatalytic performance of g-C3N4-based nanocomposite due to the synergistic effect of AgBr and ZnO semiconductors
Boorboor Azimi, Elham,Badiei, Alireza,Hossaini Sadr, Moayad
, p. 174 - 183 (2018/06/29)
In this study, we synthesized a novel visible-light-driven photocatalyst with excellent photocatalytic activity, g-C3N4/AgBr/ZnO, as a ternary nanocomposite for pollutant degradation via a facile method. This coupling was favorable due to charge transfer between the semiconductors to yield a Z-scheme photocatalysis system, and thus the separation of photo-excited electron–holes was improved. The structure, morphology, and optical properties of the photocatalyst were determined by using characterization techniques, including X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and its elemental mapping, N2 adsorption-desorption analysis, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence, fourier transform infrared spectra, and zeta potential measurements. The photocatalytic activity of the g-C3N4/AgBr/ZnO heterostructure was evaluated with different weight ratios during the degradation of the cationic pollutant methylene blue (MB) under exposure to visible light. The optimal photocatalyst with a g-C3N4 content of 30% exhibited superior activity during the degradation of MB and the rate constant of 0.041 min?1 was about 4.6 times higher than the rate constant of the pure g-C3N4. In addition, we assessed the photosensitization of MB and its effect on the photodegradation process. We propose a possible mechanism to explain the photocatalytic activity of the prepared ternary nanocomposite based on experiments with reactive species scavengers. Finally, the reusability and stability of the photocatalyst was investigated after four cycles.
Synthetic method for 1,3,5-triazine-2,4,6-triamine
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Paragraph 0022; 0027; 0028; 0030-0042, (2018/10/19)
The invention discloses a synthetic method for 1,3,5-triazine-2,4,6-triamine. The synthetic method for 1,3,5-triazine-2,4,6-triamine is characterized by comprising the following steps: taking cyanoguanidine as a starting material; dispersing the cyanoguanidine and 5-amino-1H-tetrazole in distilled water; then dropwise adding a small amount of concentrated hydrochloric acid, after dropwise adding is finished, heating to refluxing, then carrying out cooling crystallization, separating out solids, filtering under reduced pressure to obtain a filter cake, cleaning and drying the filter cake undervacuum to obtain a target compound 1,3,5-triazine-2,4,6-triamine. By the method, the reaction temperature is greatly reduced, a reaction process is gentle, requirements for a reaction container and equipment are low, and the synthetic method is simple and convenient to operate.
Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry
Chambreau, Steven D.,Koh, Christine J.,Popolan-Vaida, Denisia M.,Gallegos, Christopher J.,Hooper, Justin B.,Bedrov, Dmitry,Vaghjiani, Ghanshyam L.,Leone, Stephen R.
, p. 8011 - 8023 (2016/10/31)
The unusually high heats of vaporization of room-temperature ionic liquids (RTILs) complicate the utilization of thermal evaporation to study ionic liquid reactivity. Although effusion of RTILs into a reaction flow-tube or mass spectrometer is possible, competition between vaporization and thermal decomposition of the RTIL can greatly increase the complexity of the observed reaction products. In order to investigate the reaction kinetics of a hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) was aerosolized and reacted with gaseous nitric acid, and the products were monitored via tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Reaction product formation at m/z 42, 43, 44, 67, 85, 126, and higher masses was observed as a function of HNO3 exposure. The identities of the product species were assigned to the masses on the basis of their ionization energies. The observed exposure profile of the m/z 67 signal suggests that the excess gaseous HNO3 initiates rapid reactions near the surface of the RTIL aerosol. Nonreactive molecular dynamics simulations support this observation, suggesting that diffusion within the particle may be a limiting step. The mechanism is consistent with previous reports that nitric acid forms protonated dicyanamide species in the first step of the reaction.
