Reaction Of 2-propanol Research Articles

Selectivity of Electrochemical Reactions Based on Adsorption at Nanoporous Electrodes.

Enhancing selectivity is a pivotal area of research when electrodes are utilized as catalysts or sensors. Nanoporous electrodes are representative electrode materials for diverse applications, such as catalysts and sensors. Selectivity arising from nanoporous structures has been applied to systems involving nonfaradaic reactions such as capacitive deionization, electrochemical supercapacitors, and conductometry. Since selectivity in faradaic reactions has primarily been explored based on reactivity and molecular charge and size, we propose that the surface adsorption of reactant molecules can be considered as another crucial factor in achieving selectivity. Our observations reveal that the nonadsorptive reaction of 2-propanol and 2-butanol experienced a more pronounced enhancement compared to the adsorptive reaction of 1-propanol and 1-butanol at nanoporous Pt electrodes, owing to the nanoconfinement effect. Even within the same molecule with a mixture of adsorptive and nonadsorptive reactions, the degree of influence of the nanostructure depends on the adsorptive capacity of the reaction, which affects the overall selectivity. Moreover, the size effect of the reactants in the nanoporous electrode is also dependent on the degree of adsorption. These findings provide valuable insights into the effective utilization of nanoporous materials as catalysts or sensors.

Ecomposition of 2-propanol over Alumina supported Thoria and Potassium ion modified catalysts

A series of alumina and K ion modified supported thoria catalysts were prepared using thorium nitrate hexahydrate at different loading levels (3–20 wt% of thoria) by the impregnating method. The decomposition of 2-propanol on the surface of these catalysts was investigated. Pure g-alumina catalyst shows low activity and higher selectivity towards dehydration reaction. In contrast, thoria catalyst shows low activity and higher selectivity towards dehydrogenation reaction. The activity and selectivity of alumina supported thoria catalyst towards dehydrogenation reaction was increased with increasing the amount of ThO2 on g-alumina. However, the activity and selectivity of these catalysts towards dehydration reaction were observed to be decreased with increasing the amount of ThO2. The surface of dehydrogenation reaction of 2-propanol was increased with increasing the addition of K ion on the surface of alumina supported thoria catalysts

Real-Time Facile Detection of the WO3 Catalyst Oxidation State under Microwaves Using a Resonance Frequency.

Microwaves (MWs) are often used to enhance various heterogeneous catalytic reactions. Here, we demonstrate real-time monitoring of a catalyst’s oxidation state in a microwave catalytic reaction using a resonance frequency. The changes in the catalyst’s oxidation state during the reaction induced changes in the resonance frequency in the cavity resonator. The resonance frequency was not affected by 2-propanol adsorption, while the frequency decreased with the reduction of WO3 → WO3−x. That is, the redox state of the WO3 catalyst could be detected using the resonance frequency. The oxidation state of the WO3 catalyst was then directly observed by the resonance frequency during the dehydration reaction of 2-propanol by microwaves as a model reaction. Resonance frequency monitoring revealed that the enhanced dehydration of 2-propanol by microwaves was attributable to the reduction of the WO3 catalyst. Moreover, the temporal changes in the oxidation state of the WO3 catalyst detected by the resonance frequency coincided with that observed by operando Raman spectroscopy. Therefore, real-time resonance frequency monitoring allowed facile detection of the bulk catalyst oxidation state under microwaves without using any spectroscopic apparatus.

Synergistic effect between Ni single atoms and acid–base sites: Mechanism investigation into catalytic transfer hydrogenation reaction

Catalytic Transfer Hydrogenation (CTH) of unsaturated functional groups to obtain high value-added products has attracted considerable attention in heterogeneous catalysis. Herein, we report a Ni single atoms (SAs) catalyst anchoring to MgAl mixed metal oxide (MMO) based on structural topotactic transformation from hydrotalcite precursor, which displays an excellent catalytic behavior toward CTH of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) (conversion: 100%; selectivity: 100%; 2 h). A combination research including AC-STEM, XAFS and in situ CO-IR demonstrates that Ni species anchored by NiO coordination with different dispersion could be precisely obtained by tuning the reduction temperature: the Ni SAs (only NiO coordination) were obtained below 450 °C, and the NiNi coordination appears and increases gradually with the rise of the reduction temperature. The selective poisoning experiment, kinetic isotope effect (KIE), in situ FT-IR measurement and DFT calculation reveal the synergistic effect between metal Ni SAs and acid–base sites toward CTH of CAL. Specifically, the Ni SAs play a crucial role in dehydrogenation reaction of 2-propanol (2-POL) to supply activated H, the base sites induce α-CH cleavage in 2-POL (the rate-determining step), and the Lewis acid sites serve as the active center for CO adsorption in CAL molecule. This work demonstrates a synergetic effect between Ni SAs and acid–base sites, which would pave the way in the rational design and synthesis of high-performance SAs materials used in CTH reactions.

マイクロ波照射下での WO 3 触媒を介した 2-プロパノールの脱水反応の in situ / operando 観測

マイクロ波照射下での WO 3 触媒を介した 2-プロパノールの脱水反応の in situ / operando 観測

Modulation of the acidity of a vermiculite and its potential use as a catalytic support

The modulation and characterization of the acidity of a vermiculite were carried out, which was modified by delamination by means of hydrothermal and acid treatments with the subsequent incorporation of AlZr and AlCe species to modulate the acidity. The effect of these species was evaluated regarding the structural (XRD, XPS and IR), textural (N2 sortometry) and acidity properties (NH3-TPD, NH3-DRIFTS and CO adsorption at low temperature). The catalytic performance was studied in the dehydration–dehydrogenation reactions of 2-propanol and the hydroconversion of decane, which generate important information about the acidity properties such as the type, number and strength of acidic sites. The correlation between the number, type and acid strength with the catalytic behavior allowed to establish the important effect regarding the nature of the mineral, its method of delamination and the nature of the incorporated cation, thus generating tools for controlled processes for the potentiation of the acidity of new supports from raw vermiculite.

Potentialization of bentonite properties as support in acid catalysts

Enhancement of the main physicochemical properties of a natural bentonite was carried out by means of modifications using surfactant, reflux, microwave treatment and, subsequently, the incorporation of AlZr and AlCe species. The evolution of the main changes in each modification stage was evaluated by means of X-ray diffraction, N2 sortometry, scanning microscopy (SEM), NH3-TPD, NH3-DRIFTS and CO adsorption at low temperature. For the evaluation of the catalytic behavior, the dehydration-dehydrogenation reactions of 2-propanol and hydro-conversion of decane were used; both of which generate, in addition, information regarding the acidic properties of the materials. The correlation of the number, type and acid strength with the catalytic behavior, allowed establishing the effect produced by both the delamination method and the nature of the incorporated cation. This generated tools that allow controlling the physicochemical properties, and more specifically, the enhancement of the acidity of new supports based on this type of natural clay mineral.

Solvent-dependent regio- and stereo-selective reactions of 3-formylchromones with 2-aminobenzothiazoles and transacetalization efficiency of the product 3-((benzo[d]thiazol-2-ylimino)butyl)-4H-chromen-4-one.

Using 2-propanol as the solvent, 3-formylchromones and 2-aminobenzothiaoles formed corresponding imines, while 1° and 2°-alcohols formed the corresponding 2-alkoxy-3-enamines with selectivity for the Z-isomer. Changing the substrates with similar molecules such as 3-formylchromone with quinoline-, quinolone- and indole-3-carbaldehydes sometimes resulted in the formation of the corresponding imines, whereas replacing 2-aminobenzothiazole with amides resulted in the formation of acetals. Considering the effect of the solvent, replacing alcohols with the aprotic solvents THF and CH2Cl2 resulted in the formation of imines and enamines, which are the characteristic reactions of 2-propanol and other 1° and 2°-alcohols, respectively. 2-Alkoxy-3-enamines were found to undergo transacetalization with both short and long chain alcohols. The novelty of these reactions is that they did not require an external catalyst, all the reactions were performed at the same temperature, and purification was achieved by filtration. The transacetalization we performed herein is a new concept, which has not been reported to date. In contrast, other similar reactions, such as transalkoxylation, transalkylation, and transetherification, are performed on a commercial scale using expensive catalysts such as Otera's catalyst. The highly sensitive nature of 3-formylchromones towards variations in the substrates and solvents to form different products and the reason behind the selective formation of the Z-isomer of 2-alkoxy-3-enamines and its transacetalization efficiency need further studies to understand the reaction mechanism and possibly other factors such as solvent effects.

Spatially Nonuniform Reaction Rates during Selective Oxidation on Gold.

The nonuniform reactivity of adsorbed oxygen during the selective oxidation of methanol on Au(110)-(1×2) was demonstrated using in situ scanning tunneling microscopy (STM), establishing the importance of both atomic and mesoscale structure in determining reaction kinetics. At coverages above 0.06 ML, oxygen consumption occurs preferentially along [11̅0] direction, creating local regions completely devoid of oxygen between oxygen islands. The directionally specific reactivity is attributed to a combination of the weaker binding of oxygen atoms at chain termini and the release of surface strain induced by O bonding to Au. The generality of this phenomenon is illustrated by analogous, but kinetically contrasting behavior, for reaction of 2-propanol with oxygen covered Au(110)-(1×2). Even at low O coverages, there are structurally related changes in the reactivity for the reaction with methanol. With decreasing O coverage, a slow reaction period is followed by a fast reaction period, the latter starting when oxygen coverage decreases to ∼0.06 monolayer, independent of the initial coverage. This increase in reactivity is attributed to a sudden destabilization of the island structure. These results demonstrate that both local and mesocale structures can affect reactivity.

Surface and interface properties of polar thin films on a ferroelectric substrate: ZnO on LiNbO3 (0001) and (0001¯)

The impact of ferroelectric polarization on film growth has been studied through the deposition of polar ZnO thin films on ferroelectric LiNbO3 (0001) and (0001¯) surfaces. The growth was monitored by reflection high energy electron diffraction and characterized by x-ray photoelectron spectroscopy (XPS), x-ray diffraction, and x-ray reflectivity. The evolution of the XPS peak intensities and x-ray reflectivity data suggest that the growth was Stranski–Krastanov with a two-dimensional to three-dimensional transition and a small degree of roughness at the interface. The film maintained the substrate surface crystallography initially, then transitioned to an ordered ZnO (0001) phase after passing through a disordered regime. Higher Zn 2p XPS core level binding energies were observed on positively poled LiNbO3 and were attributed to the negative compensating charges at the positive surface n doping the ZnO film, thereby the Fermi level is pinned at the bottom of the ZnO conduction band. In addition, the reaction of 2-propanol was used as a probe to identify the polarity of thick ZnO films. The results indicate that ZnO films grown on either LiNbO3 (0001) or (0001¯) polar surfaces ultimately develop a negative polarization. Therefore, it is concluded that the LiNbO3 polar substrate has a more obvious impact over a short range near the ZnO/LiNbO3 interface but this does not translate into directing the polarization direction of thicker ZnO films.

Reaction of 2-propanol with ozone in aqueous media

This paper deals with reactions occurring in the aqueous system of 2-propanol/ozone. The considered reactions are discussed from thermodynamic and kinetic points of view. The major finding refers to the fact that 2-propanol reacts with O3 mainly via hydride transfer:(HO)(H3C)2CH + O3 → [(HO)(H3C)2C+ + HO3−]cage → (HO)(H3C)2C+ + HO3− → (H3C)2CO + H2O + O2Arguments supporting this proposed mechanism are: high exergonicity of reaction (ΔG = −234 kJ mol−1 for the first two steps), low HO yield - (2.4 ± 0.5)% and high acetone yield - (87.2 ± 1.5)%. Other oxidation products detected within the system are acetaldehyde - (1.4 ± 0.1)%, formaldehyde - (4.0 ± 0.1)%, acetic acid - (2.8 ± 0.2)%, formic acid - (0.6 ± 0.2)% and hydrogen peroxide - (1.5 ± 0.1)%. The temperature dependence of the second order rate constant for the reaction 2-propanol + O3 → products is ln kII = 29.64–8500 × T−1. The activation energy and pre-exponential factor derived from this relationship are (71 ± 3) kJ mol−1 and (7.5 ± 6.4) × 1012 M−1 s−1, respectively. At 23 °C, the second order rate constant is kII = (2.7 ± 0.1) M−1 s−1. The low reaction rate can be explained by the transfer of one hydride ion from 2-propanol to electrophilic ozone.

Acid–Base Properties of N-Doped Carbon Nanotubes: A Combined Temperature-Programmed Desorption, X-ray Photoelectron Spectroscopy, and 2-Propanol Reaction Investigation

Chemical and electronic properties of N-doped multiwalled carbon nanotubes (NCNTs) synthesized by NH3 treatment of preoxidized CNTs at 300, 500, and 700 °C have been investigated by a set of surface sensitive techniques. Temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) were applied to characterize the nature, thermal stability, and binding state of N and/or O containing surface functional groups. Acid–base properties in aqueous phase were analyzed by potentiometric pH titration, while the catalytic reaction of 2-propanol probed the acid–base behavior of the materials in the gas phase. NH3 treatment at 300 °C leads to an acid–base bifunctional surface, predominantly decorated with imide species. Contrarily, pyrrolic N is the most abundant moiety present on the sample modified at 500 °C. Here, only small fractions of lactam groups and pyridinic species are present. The incorporation of N at 700 °C leads to a carbon nanotube (CNT) surface with a well-defined basicity due to ...

In situ photoacoustic FTIR studies on photocatalytic oxidation of 2-propanol over titanium(IV) oxide

Adsorption and photocatalytic reaction of 2-propanol over titanium(IV) oxide (TiO2) were studied by Fourier transform infrared spectroscopy (FTIR) using a photoacoustic (PA) technique. At first, the validity of the FTIR system using a home-made PA cell was confirmed by comparison with conventional transmission FTIR. The spectrum of TiO2 with 2-propanol showed different propoxy peaks from those of gaseous 2-propanol as a result of chemisorption on TiO2. Finally, in situ FTIR observation of the photocatalytic oxidation of 2-propanol was carried out. Under ultraviolet irradiation, PA spectra changed due to complete oxidation of 2-propanol through acetone as an intermediate.

Biomineralization-Inspired Preparation of Zinc Hydroxide Carbonate/Polymer Hybrids and Their Conversion into Zinc Oxide Thin-Film Photocatalysts.

The development of ZnO thin films has been achieved through the conversion of zinc hydroxide carbonate thin-film crystals. Crystallization of this compound is induced by a biomineralization-inspired method with polymer-stabilized amorphous precursors. The crystals grow radially on polymer matrices, leading to the formation of zinc hydroxide carbonate/polymer thin-film hybrids that fully cover the substrate. These hybrids are converted into ZnO and retain their thin-film morphologies. The resultant ZnO thin films exhibit a preferential crystallographic orientation that is attributed to the alignment of zinc hydroxide carbonate crystals before conversion. In addition, a photocatalytic function of the ZnO thin films has been demonstrated by analyzing the oxidation reaction of 2-propanol. The biomineralization-inspired approach reported herein is a promising way to develop ZnO materials with controlled morphologies and structures for photocatalytic applications.

The role of structure and surface chemistry of carbon nanomaterials in catalytic conversion of 1,2-dichloroethane

Catalytic activity of several graphene- and diamond-based carbon nanomaterials was compared in the reaction of the 1,2-dichloroethane (DCE) conversion using the impulse microcatalytic method. Only nanodiamonds and Ni-doped nanodiamonds were active in the reaction. A comparison of XRD, XPS, DRIFTS, and BET studies suggested that nitrogen or oxygen-containing groups could be responsible for the catalytic activity in the DCE reaction. However, nitrogen-doped carbon nanoflakes, which contain much more nitrogen-containing groups, showed no activity in the DCE conversion; hence, it is unlikely that nitrogen-containing groups of nanodiamond surface are active centers in DCE conversion. The role of oxygen-containing groups was studied in a test reaction of 2-propanol dehydrogenation/dehydration – both nanotubes and nanodiamonds were active in the reaction; however, no activity of carbon nanotubes in the DCE conversion suggests that oxygen-containing groups are not active in the DCE conversion. As a result, we suggest that the carbon surface of nanodiamonds might be catalytically active in the DCE reaction.

Adsorption and dehydrogenation of 2-propanol on the surface of γ-Al2O3-supported gold

The adsorption and reactions of 2-propanol on γ-Al2O3 and γ-Al2O3-supported gold samples were investigated by infrared (IR) spectroscopy, modulated differential scanning calorimetry (MDSC) and mass spectrometry. Adsorption of the alcohol on the samples at room temperature led to formation of molecularly adsorbed 2-propanol and 2-propoxide species bonded to Al3+ sites. Treatment of γ-Al2O3 after alcohol adsorption in flowing He from 25 to 300°C led to 2-propanol desorption, without evidence of surface reactions. In contrast, when supported gold samples were exposed to the same thermal treatment, formation of acetone and H2 was observed by mass spectra of the effluent gases from the flow reactor. Concomitantly, IR spectra of the samples showed the appearance of a band at 1698cm−1, assigned to νCO vibrations of adsorbed acetone. The formation of acetone occurred by the dehydrogenation of 2-propoxide species bonded to Al3+ sites, as evidenced by (a) the decrease in the intensities of their IR bands and (b) the presence of a MDSC peak at approximately the same temperature as that at which acetone was formed and the 2-propoxide species were consumed. It is proposed that gold particles on the γ-Al2O3 surface facilitate breaking of the β-CH bond of neighboring surface 2-propoxide species to give acetone. Our results emphasize the bifunctional character of supported gold catalysts for the dehydrogenation of alcohols.

Nitridation of MgO-loaded MCM-41 and its beneficial applications in base-catalyzed reactions

Nitrogen-containing MgO-MCM-41 solid base material is prepared by nitridation of MgO-loaded mesoporous MCM-41. The ordered mesoporous structure and high surface area of MCM-41 are well preserved after MgO impregnation and nitridation, as proved by the XRD, TEM and nitrogen adsorption/desorption analysis. FTIR spectra the bridging –NH– groups and terminal –NH 2 groups are incorporated into the framework of MgO-MCM-41 by nitridation, and the base strength is expected to be enhanced due to the replacement of oxygen by nitrogen with lower electronegativity. FTIR spectra with the adsorption of different probe molecules, e.g. CO, CD 3CN and 13CO 2, are employed for the characterization of surface acidic–basic properties of MgO-MCM-41 before and after nitridation. It is revealed that the acidic hydroxyls in MgO-MCM-41 are greatly reduced through nitridation process. Compared with MgO-MCM-41, the nitridized MgO-MCM-41 material exhibits improved basic catalytic performances in Knoevenagel condensation reaction, Claisen–Schmidt reaction and dehydrogenation reaction of 2-propanol.

Photocatalytic reforming of C3-polyols for H2 production: Part II. FTIR study on the adsorption and photocatalytic reforming reaction of 2-propanol on Pt/TiO2

The adsorption behavior and the photocatalytic reforming (PR) process of 2-propanol over Pt (1wt.%)/TiO2 (PT) photocatalyst have been investigated by Fourier transform infrared (FTIR) spectroscopy. Both the adsorption complexes and the reforming intermediates formed on the PT and the gas-phase were determined and identified by FTIR spectra. The results indicated that the first layer surface of the PT mainly consisted of chemisorbed 2-propanol (Ti–OCH(CH3)2) through the condensation of 2-propanol with surface Ti–OH or dissociative adsorption with undercoordinated Ti atoms, while the second layer consisted of physisorbed 2-propanol by interaction with the chemisorbed one or the formed H2O via hydrogen-bond. Under UV irradiation, a rapidly deprotonation of 2-propoxide occurred by the attack of holes (h+) and resulted in the formation of acetone, which was then slowly oxidized to acetate and formate species by the hydroxyl radicals (OH). The carboxylates finally decarboxylate over the PT to evolve CO2 and CH4 via the photo-Kolbe reaction. According to the results, a reforming mechanism was proposed. The role of the OH groups contained in 2-propanol and its intermediates were found to serve as anchors for their adsorption and to involve the formation of h+ transport ways.

A kinetic study of 2-propanol dehydration on carbon acid catalysts

Abstract Activated carbons with high surface acidity were obtained in a single step by chemical activation of hemp residues with H 3 PO 4 and used as catalysts for the dehydration reaction of 2-propanol. Despite the washing process performed after the activation, the resulting carbons show a considerable amount of surface phosphorus as revealed by XPS. The surface acidity, predominantly of Bronsted type, was dependent on the amount of phosphorus retained on the carbon surfaces. Conversion of 2-propanol yielded only dehydration products, mostly propylene with a very low amount of di-isopropyl ether. The effect of a thermal treatment performed to carbon catalyst on the surface chemistry, acidity and dehydration activity was analyzed. A kinetic study of the catalytic dehydration of 2-propanol on the best carbon catalyst was carried out, where two different Langmuir–Hinshelwood mechanisms, via surface elimination reactions, E1 and E2, were analyzed. The rate expressions derived from both models fitted properly the experimental results and activation energy values of about 98 kJ/mol were obtained. The results indicate that the 2-propanol dehydration reaction takes place by an E2 elimination mechanism with strong E1 character.

A kinetic study of 2-propanol dehydration on carbon acid catalysts

Activated carbons with high surface acidity were obtained in a single step by chemical activation of hemp residues with H 3PO 4 and used as catalysts for the dehydration reaction of 2-propanol. Despite the washing process performed after the activation, the resulting carbons show a considerable amount of surface phosphorus as revealed by XPS. The surface acidity, predominantly of Brönsted type, was dependent on the amount of phosphorus retained on the carbon surfaces. Conversion of 2-propanol yielded only dehydration products, mostly propylene with a very low amount of di-isopropyl ether. The effect of a thermal treatment performed to carbon catalyst on the surface chemistry, acidity and dehydration activity was analyzed. A kinetic study of the catalytic dehydration of 2-propanol on the best carbon catalyst was carried out, where two different Langmuir–Hinshelwood mechanisms, via surface elimination reactions, E1 and E2, were analyzed. The rate expressions derived from both models fitted properly the experimental results and activation energy values of about 98 kJ/mol were obtained. The results indicate that the 2-propanol dehydration reaction takes place by an E2 elimination mechanism with strong E1 character.