Effect Of Different Amines Research Articles

Hydrogen-rich syngas upgrading via CO2 adsorption by amine-functionalized Cu-BTC: the effect of different amines.

Syngas produced from supercritical water gasification typically contain a high amount of CO2 along with H2. In order to improve the quality of syngas, amine-functionalized copper benzene-1,3,5-tricarboxylate (Cu-BTC) was synthesized as an effective adsorbent for selective removal of CO2 from syngas to increase the concentration of H2. The amines used in this study included monoethanolamine (MEA), ethylenediamine (EDA), and polyethyleneimine (PEI). The fundamental physicochemical character of adsorbents, CO2 adsorption capacity, and CO2/H2 selectivity were analyzed. The physicochemical characterization indicated that the structure of amine-functionalized Cu-BTC was partially damaged, which resulted in a decrease in specific surface area and pore volume. On the other hand, the enlarged pore size was beneficial for the mass transfer of gas in the adsorbent. Among these adsorbents, Cu-BTC/PEI exhibited the maximum CO2 adsorption capacity of 3.83mmol/g and the highest CO2/H2 selectivity of 19.74. It was found that the adsorption pressure is the most significant factor for the CO2 adsorption capacity. Lower temperature and higher pressure were favored for CO2 adsorption capacity and CO2/H2 selectivity, so physical adsorption by Cu-BTC played a dominant role. Moreover, Cu-BTC/PEI can be well-regenerated with stable adsorption efficiency after five consecutive cycles. These findings suggested that Cu-BTC/PEI could be a promising alternative adsorbent for CO2 capture from syngas.

Low temperature sintering of MOD assisted Ag paste for die-attach application

In this paper, we have developed a novel Ag paste containing MOD (metal organic decomposition) for assisting the sintering of nanoparticles. Based on the prepared Ag paste, the bonding joint can reach a maximum shear strength of 42.7 MPa at 175 °C. The effect of different amines on the performance of bonded joints was studied to elucidate the mechanism of MOD assisted sintering. Due to the advantage of high sintering performance, the new MOD assisted Ag paste is promising to be applied in the field of WBG device packaging.

Morphological and Optical Tuning of Lead-Free Cs2SnX6 (X = I, Br) Perovskite Nanocrystals by Ligand Engineering

In order to overcome the toxicity of lead halide perovskites, in recent years the research has focused on replacing lead with more environmentally friendly metals like tin, germanium, bismuth or antimony. However, lead-free perovskites still present instability issues and low performances that do not make them competitive when compared to their lead-based counterparts. Here we report the synthesis of lead-free Cs2SnX6 (X = Br, I) nanostructures of different shapes by using various surface ligands. These compounds are a promising alternative to lead halide perovskites in which the replacement of divalent lead (Pb(II)) with tetravalent tin (Sn(IV)) causes a modification of the standard perovskite structure. We investigate the effects of different amines on the morphology and size of Cs2SnX6 (X = Br, I) nanocrystals, presenting a facile hot-infection method to directly synthesize three-dimensional (3D) nanoparticles as well as two-dimensional (2D) nanoplatelets. The amines not only modify the shape of the crystals, but also affect their optical properties: increasing the length of the amine carbon chain we observe a widening in the bandgap of the compounds and a blue-shift of their emission peak. Alongside the tuning of the chemical composition and the reduction of the crystal size, our study offers a new insight in controlling the physical properties of perovskite nanocrystals by means of the capping ligands, paving the way for future research on lead-free materials.

The effect of hydrophilic amines on hydrothermal liquefaction of macroalgae residue

Hydrothermal liquefaction (HTL) of macroalgae residue was accomplished with seven kinds of amine catalysts for chemical and bio-oil production. The effect of HTL conditions on product distribution was investigated, and results showed that both temperature and amines concentration have significant effects on conversion of macroalgae residue to liquid products and bio-oil. The effect of different amines on composition of liquid products and bio-oil was also studied. The main ingredient of liquid products were organic acids, and the yield of organic acids declined with the increase of alkyl chain in amines. The yield of bio-oil increased with the addition of alkyl chain for primary amines and tertiary amines, while decreased for secondary amines. Methylamine had the highest yield of liquid products of 79.09wt%, and the highest bio-oil yield of 24.37wt% was obtained in the presence of triethylamine.

ChemInform Abstract: Surfactant‐Thermal Syntheses, Structures, and Magnetic Properties of Mn—Ge—Sulfides/Selenides.

AbstractEffects of different amines on the formation of manganese chalcogenidogermanates under PEG‐thermal conditions are investigated.

Controlling the shape of LiCoPO4 nanocrystals by supercritical fluid process for enhanced energy storage properties

Lithium-ion batteries offer promising opportunities for novel energy storage systems and future application in hybrid electric vehicles or electric vehicles. Cathode materials with high energy density are required for practical application. Herein, high-voltage LiCoPO4 cathode materials with different shapes and well-developed facets such as nanorods and nanoplates with exposed {010} facets have been synthesized by a one-pot supercritical fluid (SCF) processing. The effect of different amines and their roles on the morphology-control has been investigated in detail. It was found that amine having long alkyl chain such as hexamethylenediamine played important roles to manipulate the shape of the nanocrystals by selective adsorption on the specific {010} facets. More importantly, the nanorods and nanoplates showed better electrochemical performance than that of nanoparticles which was attributed to their unique crystallographic orientation with short Li ion diffusion path. The present study emphasizes the importance of crystallographic orientation in improving the electrochemical performance of the high voltage LiCoPO4 cathode materials for Li-ion batteries.

Sol–gel derived ZnO thin films: Effect of amino-additives

Zinc oxide thin films were dip-coated from an alcoholic sol of zinc acetate with different amino-additives including monoethanolamine, diethanolamine, triethanolamine, triethylamine, and ethylenediamine. Sol–gel behavior, crystal structure, optoelectronic and morphological properties of thin films were investigated with focus on the effects of different amines and drying conditions. Investigations explicate the role of chemical and physical properties of amines such as organic chains, polarity, and boiling point as the main factors that cause distinct sol–gel behavior and film properties. It is shown that different amines in different molar ratios together with drying temperature cause dramatic impacts on sol transparency, stability, and consequently on structural, optoelectronic, and morphological properties of films. Notably, monoethanolamine and triethylamine films demonstrate a preferred orientation stimulated by increased molar ratio of amines. Further investigations indicated the positive effect of elevated drying temperature particularly on those films prepared from sols with high-boiling-point stabilizers. The variation of film optoelectronics seems to depend mainly on heat treatment, whereas sol chemistry influences the optical properties indirectly through the structural alteration. Peculiar morphologies in the ethylenediamine films disappeared with adjusting the drying conditions. The size of ZnO grains were approximately independent of amine types and primarily affected by the heat treatment

Fluorescence quenching of CdSequantum dots by tertiary amines and their surface binding effect

The effect of different amines on the fluorescence of quantum dots has been discussed in the literature but the mechanism involved is not fully understood. We have studied the interaction of core CdSe quantum dots of different sizes and core-shell CdSe quantum dots with tertiary amines, such as aliphatic amines (triethylamine) and bicyclic amines (DABCO and quinuclidine), using fluorescence techniques. Fluorescence quantum yield decreases with increasing concentration of the amine following a linear Stern-Volmer behaviour (Kq=80-330 M(-1)), but relatively small changes were observed in the fluorescence lifetimes. In order to get insights into the mechanism involved, small nanoparticles (2.1 nm) were synthesized and the interaction QD surface-amine was analysed by NMR and FTIR spectroscopy.

Influence of amine template on the photoactivity of TiO2 nanoparticles obtained by hydrothermal treatment

TiO2 nanoparticles have been prepared by amine template-assisted sol–gel precipitation and further hydrothermal treatment. We have investigated the effect of different amines (hydrazine and triethylamine) in the final surface and structural properties. It has been stated that the different amounts of amine could act as an interesting template upon hydrothermal treatment. Further thermal treatment also leads to a significant improvement in the photocatalytic properties of the studied systems. Surface and morphological features notably differ from TiO2 prepared using different synthetic routes. Wide surface and structural characterization of the samples have been carried out, and correlations with precipitation pH are pointed out from this characterization. In all cases, amine template TiO2 obtained exhibit high conversion values for phenol photo-oxidation reaction. Further calcination treatment of all the studied systems clearly leads to photocatalytic conversions higher than that exhibited by TiO2 Degussa P25.

Sorption-active modified chemical fibres

The effect of topochemistry on polymer-analog transformations of graft copolymers of polycaproamide, hydrated cellulose, and polyvinyl alcohol with polyglycidyl methacrylate under the effect of different amines was established. The amine-containing sorption-active fibres exhibit high activity with respect to heavy metals and platinum-group metals.

Graft copolymerization of 4-vinylpyridine and methyl acrylate onto polyethylene film by radiochemical method

Graft copolymerization of 4-vinyl pyridine (4-VP) and methyl acrylate (MA) onto polyethylene (PE) was studied in aqueous medium in air by the mutual irradiation method. The percentage of grafting was determined as a function of the (i) total dose, (ii) monomer concentration, and (iii) amount of water. The effect of different alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and pentanol on the percentage of grafting of 4-VP and MA was studied. The effects of different amines on the percentage of grafting of 4-VP were also studied. The graft copolymers were characterized by IR spectroscopy and thermal analysis and by identifying the isolated polymer from the grafted film. Grafted PE film was tested for permeability behavior and was found to be permeable to a 0.5% aqueous sodium chloride solution. A plausible mechanism is suggested to explain the grafting of 4-VP and MA onto PE film. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 599–610, 1998

The effect of different amines added to eluents as silanol masking agents on the chromatographic behavior of some diuretics in reversed-phase high-performance liquid chromatography using C18 packings.

A preliminary gradient separation in reversed-phase liquid chromatography of a mixture of 25 solutes (diuretics, probenecide, and atenolol) is carried out using several C18 columns and an aqueous phosphoric acid solution (pH 3.2)-acetonitrile mobile phase as a control. Using this separation, the chromatographic behavior of these solutes is studied using 11 water-soluble primary, secondary, and tertiary amine modifiers in the range of 0.7-7.5 mM and a Spherisorb C18 column. This study reveals the presence in the complex sample of two groups of solutes with positive (five typical solutes showed improvements in peak symmetry and retention) or negative responses using these amines as mobile phase modifiers. After experimentation in the presence of amines, these differences are related to solute structure. Hexylamine is found to be an effective masking agent of silanols because of its structure and small required concentration. On these bases, the silanophilic and hydrophobic character of typical solutes and several C18 packings are evaluated under isocratic elution and a relative effectiveness index for amines, and a method for their assessment is proposed. The role of the amine structure on solute retention and the importance of selecting amines of suitable hydrophobic character, molecular geometry, and concentration is discussed. A model of the formation and stabilization of the silanol-amine complex based on hydrophobic and ionic interactions is also proposed.

Catalytic hydroformylation of 1-hexene over Co 2Rh 2(CO) 12 supported on inorganic carrier materials

Co 2Rh 2(CO) 12 supported on alumina, silica, magnesium silicate or zeolites catalyses 1-hexene hydroformylation to C 7-aldehydes with good yields. The effects of different amines on the 1-hexene hydroformylation were studied with Co 2Rh 2(CO) 12 strongly bound on an alumina carrier. This catalyst converted 85% of 1-hexene to C 7-aldehydes. When Et 3N is added to the hydroformylation solution, the yield of C 7-alcohols was maximum at 97%. With other cocatalysts Et 2NH, aniline, pyridine or NH 3 the yields Of C 7-alcohols were 62%, 24%, 17% and 0%, respectively. When studying the influence of the amount of Et 3N, it was found that less amine was needed for good alcohol conversion when the catalyst was supported on alumina than on silica. On the whole, the Co 2Rh 2(CO) 12 catalyst supported either on silica, magnesium silicate or zeolite in the same reaction conditions in the presence of Et 3N gave very similar C 7-oxygenate yields (99%) as Co 2Rh 2(CO) 12 on alumina. However, the alcohol contents of the above C 7-oxygenate yields were much lower than in the case Of Co 2Rh 2(CO) 12 on alumina. A 4–5 wt.% metal content of a Co 2Rh 2(CO) 12—alumina—Et 3N or Et 2NH catalyst was optimum in 1-hexene hydroformylation for 17 h. A synthesis gas pressure of 50 bar and a temperature of 100 °C provided the optimum reaction conditions.

Opposite effects of amines on lymphocyte- and monocyte-mediated ADCC

The effect of different amines on antibody-dependent cellular cytotoxicity (ADCC) activity of human mononuclear cells was tested. Whereas monocyte cytotoxic capacity was significantly stimulated in the presence of methylamine (MA), dansylcadaverine (DC) and glycine ethylester (GEE), lymphocyte ADCC was markedly suppressed by these agents. The pharmacological actions of these compounds in our system are not related to their ability to inhibit transglutaminase (TGase) enzymes, since tertiary amines such as sarcosine ethylester (SEE) and chloroquine (CQ) elicited identical responses to MA, DC and GEE. The calmodulin (CAM) inhibitors trifluoperazine (TFP) and the more specific N- (6-aminohexyl)-5-chloro-1-naphtalene sulfonamide (W-7) [Hidaka, Sasaki, Tanaka, Endo, Ohno, Fujii & Nagata (1981) Proc. natn. Acad. Sci. U.S.A., 78, 4353–4357] mimicked the effects of amines on ADCC, suggesting the possibility that a CAM-regulated process might be involved in the functional changes provoked by amines on ADCC. Finally, binding of 125I-immune complexes to the effector cells in the presence of amines showed lack of correlation between alterations in ADCC capacity and FcγR expression.