Adsorption Of N-butylamine Research Articles

The significant effect of K+ counterion in the enhancement of physicochemical and structural properties of amorphous aluminosilicates xerogels used as catalysts in the transesterification of waste frying oils

With the aim of better directing the polycondensation of oligomers during the synthesis of amorphous aluminosilicate xerogels by the sol-gel process using Na2SiO3, we reinforced the sols with K+ counterion and studied its effect on the physicochemical and structural properties of the xerogels using XRD, FTIR, N2 physisorption, SEM, EDX, and TGA techniques as well as quantitative analysis of the acid sites by N-butylamine adsorption followed by potentiometric titration. Based on the results, the introduction of K+ generated xerogels with good porosity and conferred resistance to matrix cracking. The amorphous character of the xerogels did not change after adding K+. FTIR spectra showed that the composition of the xerogels was improved after the addition of K+. Cation exchange and sulfur removal were much more efficient in the presence of K+ which improved the acidity of the xerogels. The best percentages of Si and Al were observed at the Na+/K+ ratios of 4 and 1.The enhanced xerogel prepared with Na+/K+ ratio of 1 gave a biodiesel yield of 80.44% at the optimum parameters and was used for three reaction cycles without significant loss of biodiesel yield.

Hydrothermal Synthesis and Properties of Nanostructured Silica Containing Lanthanide Type Ln-SiO2 (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu).

The nanostructured lanthanide-silica materials of the Ln-SiO2 type (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu) were synthesized by the hydrothermal method at 100 °C, using cetyltrimethylammonium as a structural template, silica gel and sodium silicate as a source of silicon, and lanthanide oxides, with Si/Ln molar ratio = 50. The resulting materials were calcined at 500 °C using nitrogen and air, and characterized by X-ray diffraction (XRD), Fourier-Transform infrared absorption spectroscopy, scanning electron microscopy, thermogravimetry (TG), surface area by the BET method and acidity measurements by n-butylamine adsorption. The XRD and chemical analysis indicated that the SiO2 presented a hexagonal structure and the incorporation of lanthanides in the structure changes the properties of the Ln-SiO2 materials. The heavier the lanthanide element, the higher the Si/Ln ratio. The TG curves showed that the decomposition of the structural template occurs in the materials at temperatures below 500 °C. The samples showed variations in specific surface area, mean pore diameter and silica wall thickness, depending on the nature of the lanthanide. The incorporation of different lanthanides in the silica generated acid sites of varied strength. The hydrothermal stability of the Ln-SiO2 materials evaluated at high temperatures, evidenced that the properties can be controlled for application in adsorption and catalysis processes.

Comparison of three-dimensional versus two-dimensional structure of mesoporous alumina as support of (Ni)MoS2 catalysts for HDS

Ordered mesoporous alumina (OMA), and commercial non ordered mesoporous alumina (CMA) were used as support to synthesize NiMo catalysts with a metal loading of 16%Wt. OMA synthesis was made using Pluronic (P123) as structure directing agent, and ethanol as a solvent. The physical and chemical properties of the supports and catalysts were characterized by XRD, nitrogen physisorption, X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), acidity of support was studied by n-butylamine adsorption followed by FTIR and catalytic performance was evaluated by hydrodesulphurization of dibenzothiophene (DBT) reaction. Main difference of supports is a two-dimensional arrangement of pores on OMA support and a three-dimensional arrangement for CMA. OMA support has more surface area available to disperse Mo and Ni species than the CMA material, besides OMA present slight acidity on its surface, and these characteristics of support leaded to obtain a NiMoS2 active phase better structured to present higher activity for DBT hydrodesulphurization and higher selectivity for direct desulfurization than the obtained for CMA supported catalyst, despite CMA presented interconnected pores and higher pore diameter.

Synthesis characterization and acid properties of niobium-containing MCM-41

In the current work, the incorporation of niobium onto the nanostructured MCM-41 material was studied. The syntheses were carried out by the hydrothermal method using cetyltrimethylammonium bromide (CTMABr) as structural template, sodium silicate and water as solvent. Niobium was introduced in the reactive medium in the form of ammonium niobium oxalate, for obtaining Nb-MCM-41 materials. In order to verify the influence of the niobium content on the properties of the material, the samples were synthesized at Si/Nb molar ratios of 15, 30, 45 and 60. The materials were calcined and characterized by BET surface area, X-ray diffraction, Fourier transform infrared spectroscopy, X-rays fluorescence, for the determination of chemical composition, and scanning electron microscopy. The acidity properties of the MCM-41 and Nb-MCM-41, as determined by n-butylamine adsorption, were investigated by thermogravimetry in the temperature range of room temperature up to 600 °C, under nitrogen gas. From TG/DTG data, the acidity values were of 3.1–3.3 mmol g−1, for materials with Si/Nb molar ratio of 60, 45 and 30. The lower value of acidity of 0.6 mmol g−1, observed for Si/Nb = 15, suggests that at this molar ratio, Nb is not incorporated in the MCM-41 structure.

Development of HZSM-12 zeolite for catalytic degradation of high-density polyethylene

The catalytic degradation of high density polyethylene (HDPE) was studied in the presence of HZSM-12 zeolites with different Si/Al ratio, by thermogravimetry and pyrolysis coupled to gas chromatography and mass spectrometry. The NaZSM-12 zeolite was synthesized by the hydrothermal method using methyltriethylammonium chloride as template. The HZSM-5 was obtained by ion exchange of NaZSM-12 with ammonium chloride, drying and subsequent calcination. The materials characterization were carried out by chemical analysis, X-ray diffraction, scanning electron microscopy, BET measurements and acidity by n-butylamine adsorption. The obtained HZSM-12 zeolites were physically mixed with HDPE in the proportion of 50%wt and submitted to thermogravimetric analyses at heating rates of 2.5; 5; 10 and 20 °C min−1. The addition of HZSM-12 to HDPE produced a decreasing in the temperature of polymer degradation, which was proportional to the zeolite acidity. The activation energy (Ea) for the process was determined from the non-isothermal model-free kinetic model proposed by Vyazovkin. The Ea decreases linearly with the concentration of acid sites on the HZSM-12 materials. From the pyrolysis data, the obtained products were typically light gases (C2-C3); liquid petroleum gases (C4-C5); and gasoline (C6-C10). This results suggest that acid zeolites are excellent materials for obtaining alternative fuels from catalytic recycling of plastics.

Thermal and catalytic pyrolysis of sunflower oil using AlMCM-41

This study was conducted on thermal pyrolysis and thermal-catalytic pyrolysis using the AlMCM-41 catalyst with a Si/Al ratio of 50, as an alternative process for turning sunflower oil into biofuel. The catalyst was characterized by X ray diffraction (XRD), N2 adsorption/desorption and total acidity by adsorption of n-butylamine, in which it was confirmed an obtainment of AlMCM-41 with an excellent surface area of 857.7 m2 g−1 and good total acidity. TG curves were used to determine the calcination temperature (450 °C) and the infrared spectroscopy (FTIR) confirmed a complete removal of the CTMA+. Two liquid fractions were obtained from the thermal and thermal-catalytic pyrolysis of sunflower oil: the first, named bio-oil, is a mixture of hydrocarbons similar to mineral diesel; the second, which was named acid fraction, is composed mainly of high acidity components. It was found by gas chromatography (GC/MS) and infrared spectroscopy (FTIR) that the proportion of acid present in the fraction of bio-oil without catalyst is higher than the proportion of acids in the fraction of bio-oil with catalyst, which indicates that the deoxygenation of the products occurred. Thus, it can be noted that the thermal catalytic sample of the bio-oil features more appropriate results to the diesel range, indicating that the acid sites found in AlMCM-41 catalysts were effective for the oil pyrolysis.

Adsorption of atmospheric carbonate and evolution of acidity during grinding of abnormal montmorillonite

Montmorillonite (MMt) from Tunisia has been subjected to fine grinding and studied using FTIR spectroscopy, X-ray diffractograms, BET surface area, Bronsted and Lewis acidity analyse, and FTIR spectroscopy. As a result, significant changes in structural vibrations when MMt was mechanochemically treated were revealed. These changes include: a shift and a gradual decrease of structural OH, Si–O, and M–OH groups (M: octahedral cations; Al, Mg and Fe), which means that an imperfection was formed in the crystal mineral via a mechanochemical treatment. The grinding is associated with amelioration of the oxidative power of clay, which is manifested by the sharpening of the infrared absorption shoulder near 880 cm–1. The thermo-FTIR adsorption of N-butylamine showed that acidity did not improve upon grinding. On the contrary, the mechanochemical treatment led to the creation of the basic sites which promote the adsorption of atmospheric dioxide carbon.

Promoting effect of cerium on the characteristic and catalytic activity of Al, Zr, and Al–Zr pillared clay

A series of pillared interlayered clays (PILCs) including Al-, Zr- and Al–Zr-PILC have been prepared and characterized by X-ray diffraction, elemental analyses, N2 adsorption, cationic exchange capacity and IR measurements after n-butylamine adsorption. Cerium introduced in the Zr4+ and/or Al3+ intercalated solution allows for an improvement of the stability and crystallinity of PILC and creates pillared clays with new properties. The resulting materials were used for the synthesis of 1,3-dioxolane. The addition of cerium has a major influence in this reaction.

Lactic Acid Esterification on Titania–Silica Binary Oxides

Lactic esters were synthesized with good yields by the reaction between lactic acid and n-butanol/ethanol over titania–silica binary oxides. These catalysts had various atomic ratios and were prepared by a coprecipitation method. XRD, n-butylamine adsorption, nitrogen adsorption, and SEM/EDS were used to characterize the oxides. In general, the turnover frequency for ester formation increased with increasing Ti content. However, the catalyst with Ti/Si atomic ratio = 1/3 (TS13) exhibited the highest ester yield (92.3%) because it had the largest surface area and the greatest amount of acid sites. The optimum Ti/Si atomic ratio for esterification is different from that (Ti/Si ∼ 9/1) reported previously for alkene isomerization. For lactic acid esterification, different optimum catalyst compositions were observed for Ti–Si, Ti–Al, and Ti–Zr mixed oxides (the best Ti/M atomic ratios = 1/3, 1/1, and 3/1 when M = Si, Al, and Zr, respectively), which might be caused by the electronegativity and acid strength di...

Development of HZSM-5/AlMCM-41 hybrid micro–mesoporous material and application for pyrolysis of vacuum gasoil

The pyrolysis of vacuum gasoil (VGO) was studied alone and in presence of HZSM-5/AlMCM-41 hybrid catalyst. This micro–mesoporous material was synthesized by the hydrothermal method using dual templates of tetrapropilamonium and cetyltrimethylammonium ions at different crystallization times. The obtained materials were washed and calcined for remotion of the organic templates. The characterization by X-ray diffraction, nitrogen surface area by the BET method, scanning and transmission electron microscopies, evidenced that typical MFI structure was embedded into the bulk of the MCM-41 matrix, in order to obtain the hybrid micro–mesoporous phase. The protonic form of the material was obtained by ion exchange with ammonium chloride solution and subsequent thermal treatment. The total acidity, as determined by n-butylamine adsorption, was equivalent to 0.75mmolg−1, in the temperature range of 300–500°C, corresponding to strong acid sites. For catalytic reaction, a physical mixture of 10% of catalyst/VGO was decomposed in a thermobalance at heating rates of 5; 10 and 20°Cmin−1, from 100 to 550°C. From TG/DTG data, applying the model-free kinetics, it was observed that the activation energy for the pyrolysis of VGO alone was ca. 125kJmol−1. For VGO physically mixed to both AlMCM-41 and HZSM-5, the value decreased to ca. 80–90kJmol−1, whereas for the hybrid, the value was the lowest, ca. 65kJmol−1, evidencing the efficiency of the combined effect of the acid sites, crystalline phase and microporosity of ZSM-5 zeolite with the accessibility of the mesoporous of the AlMCM-41 ordered material. For determination of the catalytic properties, the samples of VGO and catalyst/VGO were submitted to pyrolysis-GC–MS system at 500°C using helium as gas carrier. The VGO alone suffers decomposition to a wide range of hydrocarbons, typically C17–C41, while in the presence of catalyst, light fraction of hydrocarbons, in the range of liquefied petroleum gas (C3–C5), gasoline (C6–C10) and diesel (C11–C16) were obtained, evidencing that the HZSM-5/AlMCM-41 hybrid material is an effective catalyst for pyrolysis of VGO.

Esterification of lactic acid over TiO2–Al2O3 catalysts

N-butyl lactate was synthesized with a good yield (the maximum product yield was 95.7% at 140°C) by the reaction between lactic acid and n-butanol over TiO2–Al2O3 catalysts. These catalysts had various Ti/Al atomic ratios (ratio=1/0, 9/1, 3/1, 1/1, 1/3, 1/9, and 0/1) and were prepared by a co-precipitation method. XRD, n-butylamine adsorption, nitrogen adsorption, and SEM were used to characterize the oxides. The maximum activity was found for the catalyst with Ti/Al atomic ratio=1 (TA11). The superiority of TA11 was ascribed to its largest surface area and its maximum acidity. Under identical reaction conditions, TA11 catalyst exhibited significantly better activity than the TiO2–ZrO2 catalysts reported earlier, which should be due to the larger surface area of the former.

Use of Short-Chain Amine in Processing of Weathered/Oxidized Oil Sands Ores

In this study, short-chain amines were tested for improving bitumen recovery from weathered/oxidized oil sands ores. Three different amines, n-propylamine, n-butylamine, and n-pentylamine, were used. The emphasis of this study was to improve air bubble−bitumen attachment, measured by an induction timer. Amine addition was found to significantly decrease the induction time of the air bubble attaching to bitumen, reaching a minimum value at pH 9. Among the tested amines, the shortest induction time was obtained with n-butylamine addition. Adsorption of n-butylamine on bitumen was confirmed by ζ-potential measurements. Finally, Denver cell bitumen flotation tests confirmed the results obtained from the induction time measurements. n-Butylamine is shown to be a good chemical aid to improve the extraction of bitumen from weathered/oxidized oil sands ores. Plant process water having 10 mM n-butylamine increased bitumen recovery by more than 20% for two weathered/oxidized oil sands ore samples.

The effect of sulphuric acid activation on the crystallinity, surface area, porosity, surface acidity, and bleaching power of a bentonite

The Hançılı (Keskin, Ankara, Turkey) bentonite was activated with H 2SO 4 by dry method at 97 °C for 6 h to obtain optimum parameters for imparting a maximum bleaching power towards soybean oil. The H 2SO 4 content in dry bentonite-acid mixture was changed between 0% and 70%. The natural and activated samples were examined by X-ray diffraction (XRD), N 2 adsorption–desorption, and n-butylamine adsorption (from the solution in cyclohexane). The specific surface area ( S), specific micro–mesopore volume ( V), mesopore size distribution (PSD), and surface acidity ( n m) of the samples were determined. The bleaching power (BP) of each sample for alkali-refined soybean oil was determined. The S, V, n m, and BP increase after activation at various acid contents up to 40% H 2SO 4 without any considerable change in crystal structure of the smectite. The BP is controlled more by the PSD rather than other adsorptive properties of the bleaching earth. The optimum parameters for activation to obtain maximum bleaching power, are H 2SO 4% = 50–60, S = 250–230 m 2 g −1, V = 0.46–0.47 cm 3 g −1, n m = 9.0 × 10 −4–8.4 × 10 −4 mol g −1 and PSD mainly distributed between 1.4 and 6.0 nm.

Structural characterization and catalytic activities of titania supported iron (III) oxide catalysts: Effect of Li + impregnation

Pure Fe 2O 3/TiO 2 catalysts (1–35 wt.% Fe 2O 3) and Li-impregnated Fe 2O 3/TiO 2 catalysts (1–10 wt.% Li 2O) were prepared. The structural characteristics of pre-calcined samples were examined by using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and ESR techniques. The surface acidity was measured by the adsorption of n-butylamine in non-aqueous media. The catalytic conversion of 2-propanol at 320–360 °C using the microcatalytic pulse technique was studied. XRD of 650 °C-calcination products showed the existence of pure oxide phases as well as other spinels depending on the chemical composition. ESR spectra indicated the existence of Fe(III) in α-Fe 2O 3 phase and in spinel phase. The chemical composition, surface acidity of the catalyst and reaction temperature affect the catalytic conversion of 2-propanol.

The Effect of Heating on the Surface Area, Porosity and Surface Acidity of a Bentonite

AbstractThe Hançılı bentonite from Turkey shows significant changes in surface area, micro- and mesoporosity, surface acidity and acid strength with heating from 100 to 900°C for 2 h. The specific surface area (S) and specific micro-mesopore volume (V) of the original and heated samples were evaluated from N2 adsorption and desorption data, respectively, by standard methods. The adsorption of n-butylamine from the solution in cyclohexane on the samples was used to determine the total surface acidity (nm) and the adsorption equilibrium constant (K) was taken as a measure of the acid strength. S, V and nm having initial values of 98 m2g−1, 0.080 cm3g−1 and 4.8 × 10−4 mol g−1, respectively, stayed approximately constant as the temperature increased to 450°C and then decreased almost in parallel with each other, reaching their minimum or zero at 900°C. The total surface acidity, in general, declines with increasing temperature. The most acidic sites, however, increase with heating, and especially at dehydration and dehydroxylation. Acid strength reaches its maximum during the dehydroxylation phase at ∼600°C. It was concluded that the total surface acidity does not necessarily parallel the strength of the most acid sites.

Crystallization of ZSM-12 Zeolite with Different Si/Al Ratio

In this work the acid properties of a series of HZSM-12 zeolites with different Si/Al ratio were studied. The ZSM-12 crystals were synthesized by the hydrothermal method starting from a gel with the following molar composition: 20MTEA:10Na2O:x Al2O3:100SiO2:2000H2O, with x = 0.50, 0.67, 1, 1.25 and 2, respectively. The gels were crystallized at 140∘C for 6 days, then washed, dried and calcined to remove the MTEA template. The samples were ion-exchanged with an ammonium chloride solution and calcined again to obtain the zeolites in the acid form. The materials thus obtained were characterized by XRD, SEM, BET, TG and n-butylamine adsorption. The Si/Al ratio in the reaction mixture affects the amount of zeolite produced and the size of the particles. The XRD analysis indicated that the ZSM-12 zeolite crystallizes in a pure form only with Si/Al ratio above 33. The SEM analysis showed the presence of crystallites with very well defined prismatic shapes. The removal of the MTEA of the pores of the ZSM-12 by TG indicated that there are two kinds of internal sites occupied by MTEA inside the structure. The BET area of the ZSM-12 decreases proportionally with the crystallinity of materials. The desorption of n-butylamine showed that the acid site density is proportional to aluminum content, but the Si/Al ratio shows little influence on the relative strengths of these sites.

Catalytic Reactions of 1-Butanol over AlPO4Catalysts Induced by B2O3

A series of AlPO4–B2O3 samples containing 5–50 wt% B2O3 were prepared. Their textural properties were determined from studies of the adsorption of nitrogen at −196°C. The structural characteristics were investigated using DTA, TG, XRD and FT-IR methods. Surface acidity was determined from the adsorption of n-butylamine in non-aqueous media. The vapour-phase catalytic conversion of 1-butanol over the prepared catalysts was followed using a micro-catalytic pulse technique. The incorporation of B2O3 into AlPO4, as well as the calcination temperatures employed, led to significant changes in the textural parameters and crystallinity of the catalysts and in their surface acidity. The dehydration of 1-butanol to 1-butene and dibutyl ether (DBE) was strongly influenced by the surface acidity and the boron content of the samples.

The effect of surface adsorption on the hyper-Rayleigh scattering of large and small CdSe nanoparticles

Hyper-Rayleigh scattering is used to compare the effect of the addition of n-butylamine to large (3.2 nm) and small (1.6 nm) CdSe nanoparticles (NPs). It is found that although the adsorption of n-butylamine on large NPs enhances their nonlinear optical response, it has the opposite effect when adsorbed on the small nanoparticles for which the amine adsorption was found previously to induce structural changes. This observation is consistent with an increase in the symmetry of the nanocrystal structure such as would be observed in a phase change from a 4-coordinate wurtzite crystal structure to that of a 6-coordinate zinc-blend form.

Study of cyclohexanol decomposition reaction over the ferrospinels, A 1− xCu xFe 2O 4 (A=Ni or Co and x=0, 0.3, 0.5, 0.7 and 1), prepared by ‘soft’ chemical methods

Preparation of simple and mixed ferrospinels of nickel, cobalt and copper and their sulphated analogues by the room temperature coprecipitation method yielded fine particles with high surface areas. Study of the vapour phase decomposition of cyclohexanol at 300 °C over all the ferrospinel systems showed very good conversions yielding cyclohexene by dehydration and/or cyclohexanone by dehydrogenation, as the major products. Sulphation very much enhanced the dehydration activity over all the samples. A good correlation was obtained between the dehydration activities of the simple ferrites and their weak plus medium strength acidities (usually of the Brφnsted type) determined independently by the n-butylamine adsorption and ammonia-TPD methods. Mixed ferrites containing copper showed a general decrease in acidities and a drastic decrease in dehydration activities. There was no general correlation between the basicity parameters obtained by electron donor studies and the ratio of dehydrogenation to dehydration activities. There was a leap in the dehydrogenation activities in the case of all the ferrospinel samples containing copper. Along with the basic properties, the redox properties of copper ion have been invoked to account for this added activity.

Catalytic degradation of polyethylene over SAPO-37 molecular sieve

The degradation of high-density polyethylene (HDPE) was studied alone and in presence of silicoaluminophosphate type silicoaluminophosphate (SAPO-37) as catalyst. This material was synthesized by the hydrothermal method using tetrapropylammonium hydroxide and tetramethylammonium chloride as organic templates. The characterization by X-ray diffraction, infrared spectroscopy, thermogravimetry and scanning electron microscopy showed that typical faujasite structure for the SAPO-37 was obtained. The total acidity, determined by n-butylamine adsorption, it was equivalent to 0.558mmolg−1, corresponding to moderate acid strength. For catalytic reaction, a physical mixture of 25%SAPO-37/HDPE was decomposed in a thermobalance at heating rates of 5, 10 and 20°Cmin−1, from 380 to 520°C. At the maximum degradation rate, the products were collected in a cold trap and analyzed by a coupled gas chromatograph/mass spectrometer. The degradation of HDPE without catalyst was carried out at the same conditions for comparison with the obtained data with SAPO-37. The HDPE alone suffers decomposition to a wide range of hydrocarbons (C5–C25) while in the presence of catalyst, light hydrocarbons (C2–C12) were obtained. By the application of the Vyazovkin model-free kinetic method, it was observed that the activation energy decreased from 290kJmol−1 for HDPE alone, to 220kJmol−1 for 25%SAPO-37/HDPE, evidencing that SAPO-37 is an effective catalyst for polyethylene degradation.