Di-n-propylamine Research Articles

Surface Ligand Management Aided by a Secondary Amine Enables Increased Synthesis Yield of CsPbI3 Perovskite Quantum Dots and High Photovoltaic Performance.

Lead-halide perovskite quantum dots (PQDs) or more broadly, nanocrystals possess advantageous features for solution-processed photovoltaic devices. The nanocrystal surface ligands play a crucial role in the transport of photogenerated carriers and ultimately affect the overall performance of PQD solar cells. Significantly improved CsPbI3 PQD synthetic yield and solar-cell performance through surface ligand management are demonstrated. The treatment of a secondary amine, di-n-propylamine (DPA), provides a mild and efficient approach to control the surface ligand density of PQDs, which has an apparently different working mechanism compared to previously reported surface treatments. Using an optimal DPA concentration, the treatment can simultaneously remove both long-chain insulating surface ligands of oleic acid and oleylamine, even for unpurified PQDs with high ligand density. As a result, the electrical coupling between PQDs is enhanced, leading to improved charge transport, reduced carrier recombination, and a high power conversion efficiency approaching 15% for CsPbI3 -PQD-based solar cells. In addition, the production yield of CsPbI3 PQDs can be increased by a factor of 8. These results highlight the importance of developing new ligand-management strategies, specifically for emerging PQDs to achieve scalable and high-performance perovskite-based optoelectronic devices.

Synthesis of SAPO-41 Molecular Sieves with Different SiO2/Al2O3 Ratios and their Catalytic Performance of n-Decane Hydroisomerization

Using di-n-propylamine (DPA) as a template, SAPO-41 molecular sieves with SiO2/Al2O3 ratios (n) of 0.3, 0.5, and 0.7 were synthesized. Their structure, morphology and acidity were characterized by XRD, N2 physical adsorption, SEM, and Py-IR. All the synthesized samples have characteristic diffraction peaks corresponding to the AFO topological structure, which means that samples are pure phase SAPO-41 molecular sieve. The samples exhibited a highly ordered prismatic morphology with regular arrangement of individual grains, wrapped in flakes, and possessed complete channel structure. With the increase of n, the specific surface area and the amount of B acid showed a downward trend after increasing. Hydroisomerization reaction results of n-decane over SAPO-41 loaded with 0.5wt% Pd (Pd/SAPO-41(n)) showed that the higher the amount of B acid, the higher the conversion of n-decane,and high specific surface area and moderate B acid are favorable for yield of isomerization products. When the conversion of n-decane catalyzed by Pd/S41(0.3)-P was 88.9%, the yield of hydroisomerization products reached 83.3%.

Cleaner and sustainable approach of washing oil sands using CO2-responsive composite switchable water (CSW) with lower volatility

Abstract Switchable-Hydrophilicity Solvent (SHS) with high volatility is obstruct to environmental protection and solvent recycling in extraction process. This research aims at providing a cleaner and more sustainable approach of washing oil sands by using the CO2-responsive Composite Switchable Water (CSW). This CSW was prepared by Di-n-propylamine (DPA), N,N-dimethylethanolamine (DMEA) and water. The formation of CSW is attributed to the interaction between DPA and DMEA, which was detected by nuclear magnetic resonance hydrogen spectrum (1HNRM). The different CO2 switchable behaviors of CSW were demonstrated by the variety of conductivity and pH. Although DPA belongs to one of the SHS with high toxicity and volatility, the resulting CSW represents much lower volatility and more stability at room temperature and ambient pressure. The results show that the oil content of oil sands reduces to 2.36 wt% by using CSW with the volume ratio of 2 : 3 between DPA and DMEA aqueous solution (the volume ratio between DMEA and water is 1 : 1). Fourier Transform Infrared Spectroscopy (FT-IR) was used to demonstrate the removing of oil from the sands after being treated with CSW. The reversible change of conductivity shows the recycling ability of CSW. Finally, the economic and environmental value of washing oil sands with CSW was calculated.

Self-formation of hierarchical SAPO-11 molecular sieves as an efficient hydroisomerization support

Abstract Numerous eff ;orts have been devoted to synthesizing hierarchical zeolites by dual or bifunctional organic templates for formation of microporosity and mesoporosity. In this work, we report a convenient route for the self-formation of hierarchical SAPO-11 molecular sieves by solvent-free route without using mesoscale organic templates, which has been monitored by XRD, SEM, high resolution transmission electron microscope (HRTEM), N2 sorption, TG-DTA and MAS NMR techniques. The results show that the formation of mesoporosity in SAPO-11 is resulted from a release of di-n-propylamine (DPA) in the crystallization. Interestingly, such hierarchical SAPO-11 supported Pt catalyst exhibits enhanced catalytic performance in hydroisomerization of dodecane, compared with conventional SAPO-11.

The hydroisomerization of n-decane over Pd/SAPO-11 bifunctional catalysts: The effects of templates on characteristics and catalytic performances

Two series of pure SAPO-11 silicoaluminophosphates (S11-B(x) and S11-P(x)) with different SiO2/Al2O3 molar ratios are synthesized by employing Di-n-butylamine (DBA) and Di-n-propylamine (DPA) templates, respectively. The effects of templates on the physicochemical properties of SAPO-11 samples are investigated by XRD, N2-adsorption, SEM, XRF, 29Si MAS NMR and Py-IR measurements. The results demonstrate that S11-B(x) samples reveal different morphology and lower strong Brønsted acid density compared with S11-P(x) samples. In addition, the linear correlation between detected and calculated total Brønsted acid densities of all samples is established. The Pd/S11-B(x) and Pd/S11-P(x) bifunctional catalysts are prepared by depositing 0.5 wt% Pd on SAPO-11 samples via the incipient wetness impregnation and hydrogen reduction methods and the n-decane hydroisomerization over all catalysts are tested. The catalytic results suggest that, due to the larger CPd/CH+ ratios and fewer strong Brønsted acid sites, Pd/S11-B(x) catalysts show higher yield of i-decanes compared with Pd/S11-P(x) catalysts, while the Pd/S11-B(0.4) shows the highest i-decanes yield of 76.75% among all catalysts. The results of long-term tests of 120 h suggest that Pd/S11-B(0.4) catalyst also has better stability because of slighter aggregation of Pd metal particles and fewer blockages of micropore openings.

Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XVI. Permittivities and refractive indices for 1-alkanol + di-n-propylamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model

Relative permittivities at 1 MHz, εr, and refractive indices at the sodium D-line, nD, are reported at 0.1 MPa and at (293.15–303.15) K for the binary systems 1-alkanol + di-n-propylamine (DPA). Their corresponding excess functions are calculated and correlated. For the methanol mixture, positive values of the excess permittivities, εrE, are found. Except at high concentrations of the alcohol in the 1-propanol mixture, the remaining systems show negative values of this property. This fact reveals that the creation of (1-alkanol)-DPA interactions contributes positively to εrE, being this contribution dominant in the methanol mixture. The negative contributions arising from the disruption of interactions between like molecules are prevalent in the other mixtures. At ϕ1 (volume fraction) = 0.5, εrE changes in the sequence: methanol > 1-propanol > 1-butanol > 1-pentanol < 1-heptanol. An analogous variation with the chain length of the 1-alkanol is observed in mixtures such as 1-alkanol + heptane, +cyclohexylamine or +n-hexylamine (HxA). Moreover, for a given 1-alkanol, εrE is larger for DPA than for HxA mixtures, suggesting that in DPA solutions multimers with parallel alignment of the molecular dipoles are favoured and cyclic multimers are disfavoured when compared to HxA mixtures. The (∂εr/∂T)p values are higher for the mixtures than for pure 1-alkanols, because (1-alkanol)-DPA interactions are stronger than those between 1-alkanol molecules. Calculations on molar refractions indicate that dispersive interactions in the systems under study increase with the chain length of the 1-alkanol and are practically identical to those in HxA solutions. The considered mixtures are treated by means of the Kirkwood-Fröhlich model, reporting the Kirkwood correlation factors and their excess values.

Synthesis and Characterization of Nanocrystalline Aluminophosphate AlPO4-5 Molecular Sieve

Nanocrystalline aluminophosphate AlPO4-5 molecular sieves were synthesized by hydrothermal method (HTS). Synthesis parameters like time and temperature of crystallization were investigated. Type of template (R) and ratio of R/P2O5 were studied also. Characterization of the synthesized AlPO4-5 were done by powder X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), Fourier transform infrared (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TGA), and N2 adsorption-desorption BET analysis. XRD patterns results showed excellent crystallinity for two types of templates, di-n-propylamine (DPA) and tetrapropyl ammonium hydroxide (TPAOH) for alumminophosphate five (AFI) structure. Nano-level for particle size of 66 nm was revealed by AFM test. Good thermal stability was obtained in DSC-TGA results. Best time and temperature of crystallization of 24h and 190 O C were got. Optimum R/P2O5 for two kind of template was established.&#x0D;

New insights into the di-n-propylamine (DPA) molecule as an organic structural directing agent (OSDA) in the crystallization of AlPO4-11 molecular sieve

Di-n-propylamine (DPA) molecules induce the transformation from 4/6-MR chains to a 2D layered structure and then to 3D crystals of AlPO4-11 molecular sieves.

One-pot template-free synthesis of uniform-sized fullerene-like magnetite hollow spheres

Uniform-sized Fe3O4 hollow spheres with average diameter of 250nm and shell thickness of ∼50nm have been successfully synthesized through a simple hydrothermal route with the presence of di-n-propylamine (DPA) as a weak-base. The reaction time and DPA amount play important roles in the formation of the magnetite hollow spheres. The structures of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The results show that the single-crystalline Fe3O4 hollow spheres are composed of well-aligned magnetite nanoparticles (NPs). The magnetic property investigation shows that these hollow spheres have a higher saturation magnetization (Ms) than the solid spheres. Furthermore, a possible mechanism for the formation of magnetite hollow spheres is proposed based on the experimental observations.

One-step hydrodeoxygenation of palm oil to isomerized hydrocarbon fuels over Ni supported on nano-sized SAPO-11 catalysts

Nano-sized SAPO-11s were hydrothermally synthesized with using di-n-propylamine (DPA) as structure-directing agent in mixed n-tetradecanoamine–n-propanol–H2O medium and the Ni/SAPO-11 catalysts were prepared by incipient wetness impregnation. The catalysts was characterized by XRD, SEM, BET, H2-TPR, NH3-TPD and TG techniques and their catalytic performance was tested in hydrodeoxygenation (HDO) of palm oil to hydrocarbon fuels. Surfactant n-tetradecanoamine could mediate the minimum SAPO-11 sizes into 20–50nm. As comparing to the commercial SAPO-11, the nano-sized SAPO-11s presented significantly enlarged surfaces and mesoporous volumes, which offered sufficient space and strong interactions for dispersing Ni. One-step HDO of palm oil demonstrated that the nano-sized SAPO-1 supported Ni catalysts showed the high yield (80%) of liquid hydrocarbons, high isomerization selectivity (80%) and excellent stability due to that the catalyst presented appropriate acidity, higher Ni dispersity, balance of metal (Ni) and acid (SAPO-11) functionalities and fast diffusion for bulky palm oil and products. These promotion effects observed over the nano-sized SAPO-11 supported Ni catalysts indicated the potential application in biorefinery of vegetable oils to hydrocarbon fuels.

Benzoylation for the recovery of structure directing agent (di-n-propylamine) from the process effluent of aluminophosphate synthesis

Di-n-propylamine (DPA), a structure directing agent for (silico)aluminophosphate (AlPO4) synthesis, is lost into the mother liquor (ML, 5–6 wt%) from the filtration step. A simple benzoylation reaction could recover DPA as N,N,-dipropylbenzamide (DPBA). The reaction also leads to the recovery of more AlPO4 and a decrease in the pollution caused by the ML.

Characterization and hydroisomerization performance of SAPO-11 molecular sieves synthesized by dry gel conversion

SAPO-11 molecular sieves were synthesized by two types of dry gel conversion (DGC) methods, namely, steam-assisted conversion (SAC) and vapor phase transport (VPT), and by conventional hydrothermal (CHT) method. The properties of these samples were characterized by XRD, XRF, SEM, N 2-adsorption, Pyridine-IR and 29Si MAS NMR methods. The results show that di- n-propylamine (DPA) is a suitable structure-directing agent (SDA) for the preparation of impurity-free SAPO-11. SAPO-11 molecular sieves synthesized by SAC and VPT exhibit higher crystallinity, higher Si content and more strongly acidic sites than that synthesized by CHT. 29Si MAS NMR results demonstrated that the two samples obtained by the DGC methods contain more Si(nAl)(0 < n < 4) species than that obtained by CHT. These facts suggest that the SAC and VPT methods contribute either to better Si incorporation into the AlPO 4 framework or to better Si dispersal, thus decreasing the size of Si islands and increasing the number and strength of acidic sites. The results from the hydroisomerization of n-dodecane indicate that the Pt/SAPO-11 synthesized by SAC possesses the highest hydroconversion activity and isomer yield among those three catalysts, due to the high acidity of the molecular sieve supporter.

Effect of template content on the physicochemical characterization and catalytic performance of SAPO-11 for the hydroisomerization of n-tetradecane

Different SAPO-11 molecular sieves have been synthesized hydrothermally using mixed template of di- n-propylamine (DPA) and di- iso-propylamine (DIPA) by varying the template content or the ratio of DPA/DIPA. SAPO-11 samples were characterized using X-ray diffraction (XRD), N 2 adsorption, NH 3-temperature-programed desorption (TPD) and 29Si MAS NMR, and evaluated towards n-tetradecane skeletal isomerization. The results indicated that the template had strong influence on the crystallinity, the Si distribution and the acidity of SAPO-11. The samples prepared at template content of 1.5 and w (DPA) of 66% possessed small silicon domains and large amount of Si( n Al) (0 < n < 4) sites, and the catalysts prepared from these samples showed highest catalytic activity in the hydroisomerization of n-tetradecane because of its high acidity.

Influence of template on Si distribution of SAPO-11 and their performance for n-paraffin isomerization

SAPO-11 molecular sieves were synthesized using single agent (i.e. diethylamine (DEA), di- iso-propylamine (DIPA) and di- n-propylamine (DPA)) or a mixture of DEA and DIPA (named DEPA) as the template under hydrothermal conditions. XRD indicated that the directing effect of different templates for AEL structure decreased in the order of DEPA > DPA > DIPA > DEA. 29Si MAS NMR showed that although all SAPO-11 samples synthesized at same Si content, that prepared with the mixed template contained more Si (4Al) sites, whereas Si ( nAl, 4- nSi, 0 < n < 4) environments were predominant in the samples synthesized with single template. The results indicated that the mixed template led to a better Si dispersion and then increased the number of total acid sites of SAPO-11. In the isomerization of n-tetradecane over different Pt/SAPO-11 catalysts, the sample prepared with DEPA showed high catalytic activity and selectivity for i-C 14, which were related to the most abundant weak acid sites of the sample.

Synthesis of SAPO-41 from a new reproducible route using H 3PO 3 as the phosphorus source and its application in hydroisomerization of n-decane

In the new reproducible route, phosphorous acid (H 3PO 3) or the mixture of H 3PO 3 and phosphoric acid (H 3PO 4) are used as the phosphorus source to synthesize microporous silicoaluminophosohates. It is found that gels containing H 3PO 3 favor the formation of SAPO-41 materials. With only H 3PO 3 as the phosphorus source, pure SAPO-41 phase can be prepared with high crystallinity. When the mixture of H 3PO 3 and H 3PO 4 is used as the phosphorus source, the crystallization of SAPO-41 can be accelerated. Raman and XRD results show that SAPO-41 can be formed after crystallizing for 12 h. The dosage of the template di- n-propylamine (DPA) can be reduced in the mixed phosphorus source system. The SAPO-41 has been used to prepare catalysts for the hydroisomerization of n-decane. High selectivity of isomerization (89.5%) has been observed even at high conversion (88%) over the Pt/SAPO-41.

Thermodynamics of mixtures with strongly negative deviations from Raoult's law: Part 9. Vapor–liquid equilibria for the system 1-propanol + di- n-propylamine at six temperatures between 293.15 and 318.15 K

Vapor pressures of the 1-propanol + di- n-propylamine (DPA) system at six different temperatures between 293.15 and 318.15 K were measured by a static method. The reduction of the experimental data to obtain molar excess Gibbs energies, G E was carried out according to Barker's method, assuming that G E is represented by a Redlich–Kister equation. In the temperature range considered, the mixture shows azeotropic behaviour and negative deviation from the Raoult's law. DISQUAC describes better than the ERAS or UNIFAC (Dortmund version) models the experimental data. The analysis of the mixture structure in terms of the so-called concentration–concentration structure factor, S cc(0) reveals that interactions between unlike molecules occur in such a way that several molecules of amine interact with one molecule of alcohol.

AIPO 4-based molecular sieves synthesized in the presence of di- n-propylamine: Are the structures related?

Aluminophosphate-based molecular sieves crystallize in the presence of many organic additives. To study the influence of this organic material on the resulting structure, the products of a series of syntheses involving the use of a single organic species, di-n-propylamine (DPA), were investigated. The systematic study of the effect of specific synthesis variables led to the preparation of AIPO4-11 (AEL), VPI-5 (VFI), AIPO4-H3 (APC), MAPO-39, CoAPO-43 (GIS), and MAPSO-46 (AFS). Each sample was characterized by X-ray powder diffraction, scanning electron microscopy (SEM), Guinier-Lenne photographs, and thermogravimetric analysis. SEM did not show any particular pattern of morphological similarity between the samples. A careful examination of the structures revealed that, although the structures are quite different from one another, all have straight channels with at least 8-ring pore openings. Those with one-dimensional channel systems were prepared from gels with a lower DPA:Al2O3 ratio than those with three-dimensional ones. No cages are present in any of the structures synthesized.