Dehydrogenation Of 2-propanol Research Articles

A bilateral electrochemical hydrogen pump reactor for 2-propanol dehydrogenation and phenol hydrogenation

In this paper, an EHP is proposed for use as a reactor to complete organic dehydrogenation and biomass derivative hydrogenation simultaneously.

Bimetallic AgCu/SBA-15 System: The Effect of Metal Loading and Treatment of Catalyst on Surface Properties

Monometallic (Ag, Cu) and bimetallic (Ag + Cu) catalysts were prepared by metal loading (Ag:Cu = 0.3 and 1.8) on 3-aminopropyl-trimethoxysilane-grafted SBA-15 and calcination at 773 K and either reduction by NaBH4 before calcination or activation in inert gas after calcination. The catalysts treated in this way were fully characterized. Cu/SBA-15 samples contained CuO and oligonuclear [Cuδ+···Oδ−···Cuδ+]n clusters irrespective of the catalyst treatment. Silver–SBA-15 contained cationic silver in the form of Ag2O which was transformed to metallic Au0 by the reduction with NaBH4 and was not reoxidized during calcination. In bimetallic catalysts, different species were identified depending mainly on the Ag:Cu atomic ratio and the post modification treatment. When the excess of copper was applied the core (Ag2O)–shell (CuO) structure of the bimetallic phase was formed. If the reduction with NaBH4 was used prior to calcination, the same core–shell structure was present but with higher dispersion of CuO, manifested as a higher basicity of the catalysts revealed as a higher selectivity to acetone in 2-propanol dehydrogenation and to CO2 in methanol oxidation. The use of silver in excess led to the presence of both cationic silver and copper species in calcined AgCu(1)/S(C) material. In the sample reduced with NaBH4 and then calcined (AgCu(1)/S(RC)), metallic copper was partially surrounded by metallic silver. In bimetallic samples Cu–Ag interaction led to the electron transfer from copper to silver species enhancing their redox properties and causing the superior activity in the low-temperature total oxidation of methanol to CO2.

N-Decane dehydrogenation on Pt, PtSn and PtGe supported on spinels prepared by different methods of synthesis

The catalytic performance of Pt, PtSn and PtGe supported on ZnAl2O4 obtained by mechanochemical synthesis (MS) or coprecipitation (COPR) is studied in the production of 1-decene from the n-decane dehydrogenation. The effect of preparation methods and Sn and Ge addition to Pt on the activity and selectivity was analyzed. The catalytic characterization was carried out by using XRD, Specific surface area, 2-propanol dehydration reaction, equilibrium pH, cyclohexane dehydrogenation (CHD), cyclopentane hydrogenolysis (CPH), TPR, H2 chemisorption, XPS, TPO, and TEM. Characterization studies indicate that the addition of Sn to the Pt metal phase modifies not only the catalytic properties, but deactivation and stability as well. PtSn catalysts on both spinels were more active, with lower activity fall than PtGe ones and the higher the Sn loading, the more noticeable this effect. Besides, PtSn catalysts supported on ZnAl2O4 MS showed a more stabilizing effect.

Volcano-Curves for Dehydrogenation of 2-Propanol and Hydrogenation of Nitrobenzene by SiO2-Supported Metal Nanoparticles Catalysts As Described in Terms of a d-Band Model

To confirm whether the activity trends in multistep organic reactions can be understood in terms of the Hammer–Norskov d-band model in combination with the linear energy relations, we studied correlations between the reaction rates for dehydrogenation and hydrogenation reactions and the position of the d-band center (ed) relative to the Fermi energy (EF), the ed – EF value, of various metal catalysts. SiO2-supported metal (M = Ag, Cu, Pt, Ir, Pd, Rh, Ru, Ni, and Co) catalysts with the same metal loading (5 wt %) and similar metal particle size (8.9–11.7 nm) were prepared. The dehydrogenation of adsorbed 2-propanol in a flow of He and the hydrogenation of adsorbed nitrobenzene in a flow of H2 were tested as model reactions of organic reactions on the metal surface. As a test reaction of H2 dissociation on the surface, SiOH/SiOD exchange on the M/SiO2 catalysts in a flow of D2 is carried out. The liquid phase hydrogenation of nitrobenzene under 3.0 MPa of H2 is adopted as an organic reaction under realistic...

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.

Liquid-phase glycerol hydrogenolysis to 1,2-propanediol under nitrogen pressure using 2-propanol as hydrogen source

2-Propanol was studied as a hydrogen donor molecule in the transfer hydrogenation process to selectively convert glycerol into 1,2-propanediol under N 2 pressure and using Ni or/and Cu supported on Al 2O 3 catalysts. The results were compared to those obtained under the same operating conditions but under H 2 pressure. The results of the activity tests and catalyst characterization techniques (N 2-physisorption, H 2-chemisorption, TPD of NH 3, TPR, TPO and XPS) suggest that glycerol hydrogenolysis to yield 1,2-propanediol occurred through a different mechanism regarding the origin of the hydrogen species. When atomic hydrogen came from dissolved molecular hydrogen dissociation, glycerol was first dehydrated to acetol and then hydrogenated to 1,2-propanediol. On the other hand, when the hydrogen atoms were produced from 2-propanol dehydrogenation, glycerol was directly converted to 1,2-propanediol through intermediate alkoxide formation.

Catalytic activity of poly[(methacrylato)aluminum(III)] obtained at different gamma-radiation doses

A novel coordination polymer was obtained throughout the polymerization of aluminum(III) methacrylate at different doses (10, 20, 30, 40, 50 and 80 kGy) using gamma-radiation as initiator. The materials were characterized by electronic paramagnetic resonance (EPR), thermogravimetric analyses (TGA) and scanning electron microscopy/electron dispersive X-ray analyses (SEM/EDAX) techniques; particle size distribution and surface areas were also determined. The samples of poly[(methacrylato)aluminum(III)] obtained at different γ-doses were found to catalyze 2-propanol dehydrogenation and dehydration to acetone and propene. A noticeable activity was observed with Poly[(methacrylato)aluminum(III)] obtained at 50 kGy, which has higher conversion of 2-propanol and the highest selectivity to acetone (∼90%). Results suggest that the decomposition of 2-propanol is correlated with the effect of gamma-radiation on the structure and surface area of the catalysts.

Catalytic hydrodechlorination of trichloroethylene with 2-propanol over Pd/Al2O3

Catalytic HDC of trichloroethylene (TCE) over 1wt.% Pd/Al2O3 was carried out using 2-propanol, as solvent and hydrogen donor, in the presence of NaOH. The contribution of the homogeneous HDC reaction was important at 75°C while at 25°C thermal effects were less significant. 2-propanol dehydrogenation was evaluated at several reaction conditions and temperatures. It was found that NaOH is necessary for 2-propanol dehydrogenation. TOF of 0.001s−1 for the HDC of 0.011M TCE after 1-h reaction at 25°C was obtained. Used catalyst samples (without any pretreatment) exhibited slightly lower activities than fresh ones. Surface area and dispersion of used catalyst samples decreased because of carbonaceous residues deposition. Treated catalyst samples recovered their surface area and HDC activity of fresh ones.

Amino-grafted metallosilicate MCM-41 materials as basic catalysts for eco-friendly processes

The compounds 3-aminopropyl-trimethoxysilane (APMS), [3-(2-aminoethylamino)propyl]trimethoxysilane (2APMS) and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (3APMS) were loaded by grafting on MCM-41 matrices of various chemical compositions, aluminosilicate (AlMCM-41; Si/Al = 64) and niobosilicate (NbMCM-41; Si/Nb = 64). The materials prepared were characterized using XRD, N 2 adsorption/desorption, thermogravimetric analysis, FTIR spectroscopy and elemental analysis. Thermal stability of APMS was found not to depend on the chemical composition of the support. The higher stability of 2APMS and 3APMS was related to the hydrogen bonding between amine groups and surface hydroxyls. The models of amine grafted in MCM-41 materials were proposed. Basic activity in 2-propanol dehydrogenation and Knoevenagel reactions was found strongly dependent on the nature of the support and changed in the following order: APMS/AlMCM-41 > APMS/NbMCM-41. The acidity of the support is considered for the explanation of the activity sequence.

Design and Control of the Acetone Process via Dehydrogenation of 2-Propanol

Acetone is produced via several alternative processes, one of which is the dehydrogenation of 2-propanol (IPA). The endothermic gas-phase reaction converts IPA to acetone and hydrogen. The process consists of a vaporizer, heated tubular reactor, flash tank, absorber, and two distillation columns. The liquid fresh feed is a mixture of IPA and water. It is combined with a small IPA/water recycle stream, vaporized, and fed into the vapor-phase reactor, which is heated by high-temperature molten salt. Reactor effluent is cooled and fed to a flash tank. The gas from the tank contains most of the hydrogen but also some acetone. This gas is fed to an absorber in which a water stream is used to recover acetone. The liquids streams from the base of the absorber and the flash tank are fed to the first distillation column, which produces high-purity acetone out the top. There is also a vapor vent stream leaving the reflux drum of this column to remove the small amount of hydrogen dissolved in the feed. The second distillation column produces a high-purity water bottoms and a distillate with a composition near the IPA/water azeotrope, which is recycled back to the vaporizer. There are a number of interacting design optimization variables in this process, which illustrate some interesting design trade-offs. Removing the hydrogen without losing too much product acetone is the main challenge. Losses can occur in both the absorber off-gas and the column vent. Raising absorber pressure decreases off-gas losses but increases vent losses. Raising absorber pressure has several other effects. It raises the vaporizer pressure, which raises the required temperature and cost of the vaporizer heat source. It adversely affects kinetics because the reaction is nonequimolar and conversion decreases with increasing pressure. A higher reactor temperature is required to achieve the desired conversion. The purpose of this paper is to develop the economically optimum design considering capital costs, energy costs, and raw material costs and then to develop a plantwide control structure capable of effectively handling large disturbances in production rate.

Thermal studies on oxidation–reduction of LnCu 2 intermetallic compounds and their catalytic behavior for 2-propanol decomposition

High temperature oxidation–reduction studies were undertaken on binary intermetallic compounds LnCu 2 (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Tm, Yb). A two steps cycle was optimized by O 2-TG and H 2-TG or H 2-TPR studies along the lanthanide series. The oxidation mass uptake occurs over a wide range of temperature (200–900 °C), leading to two bimetallic copper–lanthanide oxides families according to the lanthanide: 3CuO·Ln 2CuO 4 (Ln = La, Pr, Nd, Eu, Gd) and 2CuO·Ln 2Cu 2O 5 (Ln = Dy, Tm, Yb), except for CeCu 2 that gives 2CuO·CeO 2. Under hydrogen, all systems exhibit two reduction steps accompanied by mass losses in the 150–600 °C temperature range. The first mass loss is linked to the reduction of CuO, whereas the second mass loss corresponds to copper reduction in the Ln 2CuO 4 or Ln 2Cu 2O 5 phase with concomitant formation of Ln 2O 3. The reduction products were characterized by XRD and different stoichiometries were obtained according to the lanthanide: 2Cu/CeO 2, 3Cu/Ln 2CuO 4 or 2Cu/Ln 2Cu 2O 5, after the first reduction step, and 4Cu/Ln 2O 3 after the second reduction one. Therefore, the binary intermetallic compounds LnCu 2 decompose into a copper–rare earth oxide phase that after reduction leaves their surface highly enriched on the copper. The structure of the oxidized and reduced intermetallics can best be described as copper embedded in lanthanide oxides (Ln 2O 3) or “type supported catalysts” and exhibited activity for the 2-propanol oxidative dehydrogenation–dehydration reaction, which was also used to characterize their acid–base properties.

Characterization and acidic properties of Al-SBA-15 materials prepared by post-synthesis alumination of a low-cost ordered mesoporous silica

A series of Al-containing SBA-15 type materials with different Si/Al ratio, were prepared by post-synthesis modification of a pure highly ordered mesoporous silica SBA-15 obtained by using sodium silicate as silica source, and amphiphilic block copolymer as structure-directing agent. A high level of aluminum incorporation was achieved, reaching an Si/Al ratio of up to 5.5, without any significant loss in the textural properties of SBA-15. These materials were fully characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 27Al NMR spectroscopy, and N 2 adsorption at 77 K. The acid properties of these materials have been evaluated by NH 3-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FTIR spectroscopy. The effective acidity of these materials was evaluated using two catalytic reactions: 2-propanol dehydrogenation and 1-butene isomerization. The adsorption of basic probe molecules and the catalytic behavior revealed an evolution of the acid properties with the Al content. These studies have shown that the Al-SBA-15 materials contain Brønsted and Lewis acid sites with medium acidity which makes them appropriate to be used as acid catalysts in heterogeneous catalysis, catalytic supports, and adsorbents.

Fundamental study of a non-steady operation for 2-propanol de-hydrogenation

The de-hydrogenation of 2-propanol and the hydrogenation of acetone proceed reversibly. This pair of reactions is a promising candidate for a chemical heat pump process or a hydrogen storage process. The efficiency of this process mainly depends on a chemical equilibrium and is not a high value because of low equilibrium conversion of dehydrogenation of 2-propanol. A new operation method, which is independent of an equilibrium of gas phase reaction, was introduced to the de-hydrogenation step. The reactant, 2-propanol was fed in the form of liquid phase through a spray nozzle on a heated Pt/Al 2O 3/Al catalyst plate. It is vaporized and reacted on the plate, then the product that was adsorbed on it was released. This series of non-steady operations was repeated cyclically at some time interval. Kinetic study for overall reaction rate was conducted. Phenomena on a catalyst plate surface were analyzed by dividing into a reaction phase and an evaporation phase, respectively.

Microstructural and Auger Microanalytical Characterization of Cu-Hf and Cu-Ti Catalysts

Degradation processes occurring at the surface and in the bulk of Cu-based amorphous alloys during cathodic hydrogen charging were used for promoting the catalytic activity of such alloys. These processes modifying the structure, composition, and morphology of the substrate proved to be useful methods for transforming Cu-Hf and inactive Cu-Ti amorphous alloy precursors into active and durable catalysts. Indeed, their catalytic activity for dehydrogenation of 2-propanol increased up to a conversion level of approximately 60% at selectivities to acetone of about 99% for Cu-Ti and to conversion of approximately 90% at selectivities of approximately 95% for Cu-Hf. Previous attempts carried out by aging in air or hydrogen charging from the gas phase resulted in a maximum conversion level up to 15% for Cu-Hf and up to 3% for Cu-Ti. High resolution Auger spectroscopy allowed changes occurring during the activation process to be identified, namely, the formation of small Cu particles on the HfO2 surface and the formation of highly porous particles containing mostly Cu and some Ti and O (Cu-Ti-O) on a Cu-Ti substrate. Differences in the chemistry and structure of both catalysts are discussed, and the implications for catalytic function are considered. A probable configuration of active sites on the Cu-Ti-O/Ti-O-Cu catalyst for dehydrogenation of 2-propanol is proposed.

Phosphomolybdic acid supported on silica gel and promoted with alkali metal ions as catalysts for the esterification of acetic acid by ethanol

Different ratios of phosphomolybdic acid PMA supported on silica gel (1–30 wt%) and promoted with alkali metal hydroxide have been prepared by an impregnation method and calcinated at 350 °C for 4 h. The catalysts were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction, FT-IR spectroscopy and N 2 adsorption measurements. The surface acidity and basicity of the catalysts were determined by adsorption of pyridine and the dehydration–dehydrogenation of 2-propanol. The gas-phase esterification of acetic acid by ethanol was carried out in a conventional flow bed reactor. The results clearly revealed that among the PMA loading, the use of 10 wt% catalyst showed maximum yield of ethyl acetate. This catalyst also improved on addition of Na or K-hydroxide. These results were correlated with the structure and the acid–base properties of the prepared catalysts.

Cathodic hydrogen charging as a tool to activate Cu–Ti amorphous alloy catalysts

Degradation processes occurring at the surface and in the bulk of Cu-based amorphous alloys during cathodic hydrogen charging were used for enhancing their catalytic activity. Thus, the degradation processes caused by hydrogen charging (modifying the structure, composition and morphology of the substrate) proved to be useful methods of transforming Cu–Ti amorphous alloy precursors into active and stable catalysts. Hydrogen charging was applied to Cu60–Ti40 amorphous ribbons in an acid solution (0.1 M H 2SO 4) in order to bring about pronounced morphological and structural changes. The samples were then catalytically tested for dehydrogenation of 2-propanol. Catalytic activity increased up to a conversion level of ∼60% at selectivities to acetone of about 99%. The chemical and morphological changes were followed by SEM (Hitachi 3500N) and Auger electron microanalysis (Microlab 350). Porosity and specific surface area were measured (ASAP 2010 Sorptometer), and hydrogen content was determined by elemental analysis. The rather low average specific surface area and porosity, as well as a lack of Cu 0 both before and after the catalytic test suggest that the generally accepted mechanism for the dehydrogenation of alcohols over copper catalysts with the involvement of Cu 0 is not operative here.

Characteristics of a Hydrogen Concentration Cell Constituted with a Redox Pair of 2-Propanol Dehydrogenation and Acetone Hydrogenation

Abstract A hydrogen concentration cell, constituted with a redox pair of 2-propanol dehydrogenation and acetone hydrogenation on electrode catalysts, has been studied, with which low-quality waste heat below 100 °C can be converted into electric power. The magnitudes of the open-circuit voltage (VOC) of this cell were found to be dependent on the anode abilities concerned with C–H bond splitting and hydrogen spillover. The kinetical spillover capabilities of carbon-supported Pd-based composite metal catalysts were obtained separately and compared with the magnitudes of VOC, whereas the catalytic dehydrogenation activities for 2-propanol were more closely related with the magnitudes of a short-circuit current (ISC).

Catalytic activity of Cu-based amorphous alloy ribbons modified by cathodic hydrogen charging

Since hydrogen is known to be one of the most efficient embrittling atomic species, cathodic hydrogen charging was used in an attempt to modify the structure, composition, and morphology of Cu-based amorphous alloy ribbons. Various methods of analysis such as X-ray electron microanalysis, SEM, high resolution Auger microanalysis (SAM), with varying lateral resolution and different information depths, as well as measurements of specific surface area, porosity and catalytic tests, were used to follow the changes within the ribbons and at the surface, and their interrelations with catalytic activity. The activity in a test reaction (dehydrogenation of 2-propanol) was enhanced up to conversion levels of 66% for Cu–Ti and of 88% for Cu–Hf, which are much higher than those obtained with all other pre-treatments previously applied. The rather low specific surface area and porosity, as well as a lack of Cu 0 both before and after the catalytic test suggest that the generally accepted mechanism for the dehydrogenation of alcohols over copper catalysts with the involvement of Cu 0 is not operative here.

Effect of Catalytic and Electrochemical Acetone Hydrogenation on the I–V Characteristics of an Acetone/Hydrogen-Based Thermally Regenerative Fuel Cell

Abstract A thermally regenerative fuel cell, converting low-quality heat at around 100 °C directly into electric power, is composed of a redox reaction pair of acetone hydrogenation and 2-propanol dehydrogenation. The magnitude of its open-circuit voltage (VOC) was determined by the Gibbs energy change of acetone hydrogenation, without exhibiting activation polarization. Its short-circuit current (ISC) was insensitive to the extents of catalyst loading at the anode, in contrast to the cathode, because acetone hydrogenation proceeded more slowly than hydrogen dissociation. The ISC characteristics were improved with increasing sulfuric acid concentrations at the cathode, which would have resulted from the rate enhancement of acetone reduction due to more abundant protons usable at the catalyst sites. Both VOC and ISC of the fuel cell were increased along with increasing the acetone/2-propanol ratio in the catholyte, suggesting favorable effects of the thermodynamical acetone activity and the coverage increment of acetone at the same cathode catalyst sites.

Effect of cathodic hydrogen charging on catalytic activity of Cu?Hf amorphous alloys

Hydrogen charging of Cu65Hf35 and Cu61Hf39 amorphous alloy (AA) ribbons at i =−1 mA/cm 2 in an alkaline solution (0.1 M NaOH) was used to study the effect of hydrogenation on the processes of morphology and crystallization. A similar procedure was applied in an acid solution (0.1 M H 2 SO 4 ) to introduce more hydrogen to bring about more pronounced morphological and structural changes. The samples were then catalytically tested for dehydrogenation of 2-propanol. Catalytic activity increased up to 88% at selectivities to acetone of about 95%. The structural, chemical, and morphological changes were followed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray electron probe microanalysis (WDS). The hydrogen content was determined by elemental analysis, or by gas extraction.