2-propanol Dehydration Research Articles

Azeotropic distillation for 1-propanol dehydration with diisopropyl ether as entrainer: Equilibrium data and process simulation

Azeotropic distillation process is widely used to separate non-ideal binary mixtures into their constituent pure components. 1-Propanol dehydration was used as case study and diisopropyl ether was analysed as possible entrainer in an azeotropic distillation. The separation of some alcohols from their aqueous solution is a challenging task because these aqueous mixture forms minimum boiling azeotrope.In this way, isobaric vapor-liquid and vapour-liquid-liquid equilibrium data were measured for the 1-propanol+ water + diisopropyl ether ternary mixture at 101.3 kPa. The data were correlated by NRTL and UNIQUAC models.A separation sequence (a decanter and a single-feed distillation column) for 1-propanol dehydration using diisopropyl ether was proposed. The simulation of the separation sequence was carried out satisfactorily by Aspen Hysys® using the thermodynamic model NRTL with the binary parameters obtained in this work. Moreover, the effect of temperature decantation was investigated in order to reduce the energy demand of the process.

Study of the performance and stability in the dry reforming of methane of doped alumina supported iridium catalysts

Abstract Iridium catalysts supported on alumina doped with both alkaline (Na and K) and alkaline earth metals (Ba, Ca and Mg) of different concentrations (1, 5 and 10 wt%) were tested in the dry reforming of methane. Supports were characterized by X-ray diffraction, BET surface area, temperature-programmed desorption of CO2 and 2-propanol dehydration. Catalysts were characterized by temperature-programmed reduction, TEM, XPS, cyclohexane dehydrogenation and cyclopentane hydrogenolysis. Dopants were showed to suppress the acidity of the support and the γ-Al2O3 phase remained in the supports doped with Ca, Ba, Na and K after calcination at 800 °C, whereas a phase transition to magnesium aluminate was found for magnesium doped alumina. Stability tests, using long time dry reforming reactions, showed that iridium catalysts have high sintering resistance, their metallic phases being very stable since neither carbon deposition nor sinterization processes were observed.

From destructive CCl4 adsorption to grafting SO3H groups onto activated carbon fibers

Nanoporous activated carbon fibers (BusofitTM, BACF) showed effective adsorption of carbon tetrachloride (CTC) vapors. About 2.50 mmol × g−1 of chlorine, in the form of trichloromethyl and chlorine groups, can be grafted onto BACF surface by thermal decomposition of CTC at 450 °C. To obtain solid acids, this chlorinated BACF, the brominated and pristine BACFs, taken for comparison, were subjected to progressive sulfidation, hydrolysis and oxidation reactions for grafting sulfonic groups. By this wet route, sulfonic groups can substitute only 1.1–1.4 mmol × g−1 of the grafted chlorine groups. Nevertheless, solid acids obtained in this way have high catalytic performance in the 2-propanol dehydration to propene. For these catalysts, in the range from 180 to 220°C, a 100% alcohol conversion with 100% selectivity to propene could be reached. Thermoprogrammed desorption and thermal analysis revealed that the pyrolytic chlorination triggers the highest thermal stability of grafted sulfonic groups, and, they can repeatedly act in the dehydration reaction.

Diisopropyl ether production via 2-propanol dehydration using supported iron oxides catalysts

In this work, we studied the DIPE (C6H14O) production as an oxygenated compound from the catalytic performance of Fe and Cu oxides supported over alumina, on the 2-propanol dehydration reaction. The impregnation acidity effect was investigated. Samples at acid, moderately acidic, and basic pH were prepared. They were tested at 250 °C in a pilot micro-plant at atmospheric pressure. Catalytic results concluded the Fe3O4/γ-Al2O3 impregnated to an acid pH showed the highest selectivity toward DIPE with adequate activity. All the catalysts at basic pH showed a complete selectivity to propylene (C3H6). The yield of DIPE on the acidity reflects that is a linear function, which is valuable for a more rational design of new catalysts. The catalysts were characterized by adsorption-desorption of N2, X-ray diffraction, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The correlation between the textural and morphological properties of our catalysts and their catalytic activity was discussed.

A Characterization Study of Reactive Sites in ALD-Synthesized WOx/ZrO2 Catalysts

A series of ZrO2-supported WOx catalysts were prepared using atomic layer deposition (ALD) with W(CO)6, and were then compared to a WOx/ZrO2 catalyst prepared via conventional impregnation. The types of sites present in these samples were characterized using temperature-programmed desorption/thermogravimetric analysis (TPD-TGA) measurements with 2-propanol and 2-propanamine. Weight changes showed that the WOx catalysts grew at a rate of 8.8 × 1017 W atoms/m2 per cycle. Scanning transmission electron microscopy/energy-dispersive spectroscopy (STEM-EDS) indicated that WOx was deposited uniformly, as did the 2-propanol TPD-TGA results, which showed that ZrO2 was completely covered after five ALD cycles. Furthermore, 2-propanamine TPD-TGA demonstrated the presence of three types of catalytic sites, the concentrations of which changed with the number of ALD cycles: dehydrogenation sites associated with ZrO2, Brønsted-acid sites associated with monolayer WOx clusters, and oxidation sites associated with higher WOx coverages. The Brønsted sites were not formed via ALD of WOx on SiO2. The reaction rates for 2-propanol dehydration were correlated with the concentration of Brønsted sites. While TPD-TGA of 2-propanamine did not differentiate the strength of Brønsted-acid sites, H–D exchange between D2O and either toluene or chlorobenzene indicated that the Brønsted sites in tungstated zirconia were much weaker than those in H-ZSM-5 zeolites.

Vapor–Liquid Equilibria for 2-Propanol Dehydration through Extractive Distillation Using Mixed Solvent of Ethylene Glycol and Choline Chloride

The mixed solvent of ethylene glycol (EG) and choline chloride (ChCl) was tested as an entrainer for 2-propanol dehydration by extractive distillation. Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa for the quaternary system water + 2-propanol + EG + ChCl. The NRTL equation was used for the modeling of the quaternary VLE. Mean absolute deviations were 0.26 K and 0.0036 for equilibrium temperature and vapor mole fraction of 2-propanol, respectively. As compared with EG alone, the existence of ChCl in the solvent significantly decreases the activity coefficient of water and increases the activity coefficient of 2-propanol, both enhancing the relative volatility of 2-propanol to water. The azeotrope of water +2-propanol can be removed with the addition of the deep eutectic mixture EG + ChCl 2:1 at a solvent mass fraction of 0.157. The mixed solvent may be readily applied in extractive distillation of 2-propanol and water, replacing the frequently used mixed solvent of ethylene glycol and potassium acetate.

Regularities of Pd/C-catalyzed reduction of trichlorobiphenyls with 2-propanol in basic medium

Reduction of a series of trichlorobiphenyls with 2-propanol in basic medium catalyzed by Pd/C has been studied. Regioselectivity of the reduction has been determined. In the studied cases, the chlorine atom in para or meta positions of the more substituted ring has been more reactive. Using isotope labeling, it has been demonstrated that the reaction occurs via the stage of 2-propanol dehydration on palladium catalyst, followed by catalytic hydrogenation of the polychlorinated biphenyls.

Acidic properties of Si- and Al- promoted TiO2 catalysts: Effect on 2-propanol dehydration activity

The effect of Si and Al promoted in TiO2 catalysts on both acid-base properties and 2-propanol dehydration was studied. The sol-gel method was used to prepare pure TiO2 and TiO2-Al2O3 and TiO2-SiO2 mixed oxides with 1%, 3% and 10% of Al2O3 or SiO2. The structure and surface characterization (XRD, TG-DTA, N2 sorption, 27Al and 19Si MAS NMR) revealed that the promoted cations were dispersed in the TiO2 lattice. The acid and basic sites density was measured by NH3-TPD and CO2-TPD. FTIR-pyridine-TPD revealed predominantly Lewis-type acidity for all these catalysts and a low presence Brønsted-type acidity was detect only for 10% SiO2 promoted catalyst. The change in the activity of 2-propanol decomposition was useful to detect the effect of type and content of cation in the acid-base properties of promoted catalysts. The acid-base molar ratio of the catalytic surface was increased as a function of content of Al and Si and it was related to the increase in the alcohols decomposition activity. Dehydration activity was more sensitive for the Si-promoted catalysts than the Al-promoted ones, showing an important role of cation coordination in the acidic and catalytic properties of these mixed oxides.

Water effects on the acidic property of typical solid acid catalysts by 3,3-dimethylbut-1-ene isomerization and 2-propanol dehydration reactions

Two model reactions, namely the Brønsted-acidity-specific skeletal isomerization of 3,3-dimethylbut-1-ene for evaluating the Brønsted acidity and dehydration of 2-propanol for the overall acidity at the catalyst surface, were employed in this work to measure the effect of water on the surface acidic property of typical solid catalysts (HZSM-5, γ-Al2O3 and Nb2O5). For the isomerization reaction, water addition in the reaction feed produced little effect on the catalysis of HZSM-5 but significantly positive effect on the catalysis of Nb2O5; the typical Lewis acidic γ-Al2O3 showed no activity for this reaction in either the presence or absence of water. For the dehydration reaction, the effect of water was generally negative on the catalysis of every catalyst, demonstrating that water presence resulted in poisoning more or less of the Lewis acidity on the catalyst surface. Water poisoning of the Lewis acidity on Nb2O5 also resulted in generation of Brønsted acidity and the higher the H2O partial pressure (or H2O-to-substrate ratio) the higher the newly generated Brønsted acidity. However, generation of Brønsted acidity did not happen on γ-Al2O3 and HZSM-5, regardless of the H2O partial pressure. Three Nb2O5 samples with varying calcination temperature were involved, and their behavior clearly indicated that the water effects on Nb2O5 also depended sensitively on the sample calcination temperature. Moreover, water presence increased the activation energy and selectivity for di-isopropyl ether of the dehydration reaction over γ-Al2O3 and Nb2O5, and thus affected the acidity distribution at the catalyst surface during the reaction.

2-Propanol Dehydration via Extractive Distillation Using a Renewable Glycerol–Choline Chloride Deep Eutectic Solvent: Vapor–Liquid Equilibrium

A renewable deep eutectic solvent, glycerol–choline chloride (molar ratio 2:1), was tested as an entrainer for dehydration of 2-propanol by extractive distillation. Isobaric vapor–liquid equilibrium data for the quaternary system water + 2-propanol + glycerol + choline chloride were measured at 100 kPa. With the addition of the deep eutectic solvent, the azeotrope of water + 2-propanol can be removed at a solvent mass fraction of 0.142, which is much smaller than the minimum solvent mass fraction of 0.229 for glycerol alone. With regard to the relatively low viscosity as compared with glycerol, the deep eutectic solvent may have better performance when used as entrainer for 2-propanol dehydration. The NRTL equation was used for the modeling of the quaternary vapor–liquid equilibrium data. Binary parameters of water + 2-propanol, water + glycerol, and 2-propanol + glycerol were fixed as the same for the system water + 2-propanol + glycerol and were taken from the literature. The correlation appeared to be ...

Enhanced (photo)catalytic activity of Wells-Dawson (H6P2W18O62) in comparison to Keggin (H3PW12O40) heteropolyacids for 2-propanol dehydration in gas-solid regime

Catalytic and photocatalytic 2-propanol dehydration to propene at atmospheric pressure and a temperature range of 60–120°C were carried out in gas-solid regime by using bare and supported Keggin H3PW12O40 (PW12) and Wells-Dawson H6P2W18O62 (P2W18) heteropolyacids (HPAs). Binary materials were prepared by impregnation of the HPAs on commercial SiO2 and TiO2. The Wells-Dawson was in any case more active than the Keggin heteropolyacid and the differences were enhanced when the supported samples were used. In particular, Wells-Dawson HPA supported on TiO2 and under irradiation showed the highest activity. The HPA species played the key role both in the catalytic and photo-assisted reactions. The acidity of the cluster accounts for the catalytic role, whereas both the acidity and the redox properties of the HPA species were responsible for the increase of the reaction rate in the photo-assisted catalytic reaction. The estimated apparent activation energy resulted always lower for the photocatalytic process than for the catalytic one.

Functionalization of activated carbon surface with sulfonated styrene as a facile route for solid acids preparation

We propose a facile route for the surface functionalization of activated carbons (ACs), which are used as a solid matrix with good mechanical properties, but have the deficiency of the active surface sites to form the AC-based solid acids (ACSA) by the direct chemical method. The route includes three stages that provide active and stable strong acidic surface layer. The surface chemistry changes at the functionalization stages were controlled with thermogravimetric (TG) and thermoprogrammed desorption (TPD) methods. N2 adsorption-desorption studies demonstrate the conservation of the AC meso- and macroporosity. According to XPS, DRIFT, TG-TPD-IR, and potential titrimetry data, the ACSA obtained by sulfonation of the styrene functionalized AC are contained up to 1.1 mmol g−1 of the strong acidic SO3H groups. The surface functionalization, as reported route, gives no prominent structural changes, from XRD data, the large macropores and transport channels maintain, from SEM data, and MicroRaman spectra show no defecting of the initial carbon matrix. The obtained ACSA are effective catalysts for the dehydration of 2-propanol and combine the high efficiency of work with the increased thermal stability of the surface layer. The thermoresistance of the ACSA significantly exceeds that of the Amberlyst-15 WET catalyst.

Catalytic activity of carbon nanotubes in the conversion of aliphatic alcohols

Carbon nanotubes (CNTs) obtained via the catalytic pyrolysis of hexane at 750°C were studied as the catalysts in conversion of C2–C4 alcohols. The efficiency of CNTs as catalysts in dehydration and dehydrogenation of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol was studied by means of pulse microcatalysis. The surface and structural characteristics of CNTs are investigated via SEM, TEM, DTA, BET, and XPS. CNTs are shown to be effective catalysts in the conversion of alcohols and do not require additional oxidative treatment. The regularities of the conversion of aliphatic alcohols, related to the properties of the CNTs surface and the structure of the alcohols are identified.

Keggin heteropolyacids supported on TiO2 used in gas-solid (photo)catalytic propene hydration and in liquid-solid photocatalytic glycerol dehydration

(Photo)catalytic propene hydration to 2-propanol and glycerol dehydration to acrolein were carried out by using Keggin heteropolyacids (HPAs) supported on TiO2. Binary materials have been prepared by impregnation of H3PW12O40, H3PMo12O40 and H4SiW12O40, on TiO2 Evonik P25. Moreover, a binary material consisting of H4SiW12O40 and TiO2 was prepared via a hydrothermal treatment and tested for the same reactions. All the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with energy dispersive X-ray (EDX) measurements, diffuse reflectance spectroscopy (DRS), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The supported Keggin HPA species played a key role both for the catalytic and for the photo-assisted catalytic reactions due to their strong acidity and ability to form strong oxidant species under UV irradiation.

Supported H3PW12O40 for 2-propanol (photo-assisted) catalytic dehydration in gas-solid regime: The role of the support and of the pseudo-liquid phase in the (photo)activity

Catalytic and photocatalytic 2-propanol dehydration was carried out by using a supported Keggin heteropolyacid H3PW12O40 (PW12). Binary materials were prepared by impregnation and/or solvothermal treatment by using commercial supports: SiO2 (Mallinckrodt), TiO2 (Evonik P25) and multiwall carbon nanotubes (Sunnano) or home solvothermically prepared SiO2 and TiO2. All the materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with EDX microanalysis, specific surface area measurements, diffuse reflectance spectroscopy (DRS), FTIR and Raman spectroscopy. (Photo)catalytic 2-propanol dehydration was studied in gas-solid regime by using a continuous (photo)reactor working at atmospheric pressure and 80°C. FTIR spectra of the gas-phase over the PW12-support composites, where 2-propanol had been previously adsorbed, were recorded. Propene and diisopropyl ether were the main reaction products. For the continuous photo-assisted runs the reactor was also illuminated with UV light. The apparent activation energy of 2-propanol catalytic and photocatalytic dehydration was determined in the range 60–120°C.The irradiance increased significantly the dehydration reaction rate. Important differences were observed between the different supported materials. The Keggin heteropolyacid species played a key role both for the catalytic and the photo-assisted catalytic reactions; in fact, the acidity of the cluster accounts for the catalytic role, whereas both the acidity of the cluster and the oxidant ability of PW12 were responsible for the increase of the reaction rate of the photo-assisted catalytic reaction. Moreover, the photo-generated electrons on the solid semiconductor conduction band can account for a further increase of the reaction rate, when the heteropolyacid was supported on TiO2. Formation of a pseudo-liquid phase played an important role to determine the (photo)activity.

Dehydration Pathways of 1-Propanol on HZSM-5 in the Presence and Absence of Water.

The Brønsted acid-catalyzed gas-phase dehydration of 1-propanol (0.075-4 kPa) was studied on zeolite H-MFI (Si/Al = 26, containing minimal amounts of extra framework Al moieties) in the absence and presence of co-fed water (0-2.5 kPa) at 413-443 K. It is shown that propene can be formed from monomeric and dimeric adsorbed 1-propanol. The stronger adsorption of 1-propanol relative to water indicates that the reduced dehydration rates in the presence of water are not a consequence of the competitive adsorption between 1-propanol and water. Instead, the deleterious effect is related to the different extents of stabilization of adsorbed intermediates and the relevant elimination/substitution transition states by water. Water stabilizes the adsorbed 1-propanol monomer significantly more than the elimination transition state, leading to a higher activation barrier and a greater entropy gain for the rate-limiting step, which eventually leads to propene. In a similar manner, an excess of 1-propanol stabilizes the adsorbed state of 1-propanol more than the elimination transition state. In comparison with the monomer-mediated pathway, adsorbed dimer and the relevant transition states for propene and ether formation are similarly, while less effectively, stabilized by intrazeolite water molecules.

Computational Insights into the Role of Metal and Acid Sites in Bifunctional Metal/Zeolite Catalysts: A Case Study of Acetone Hydrogenation to 2-Propanol and Subsequent Dehydration to Propene

We employ electronic structure calculations to elucidate the catalytic pathways on bifunctional metal/zeolite catalysts by modeling a HZSM-5-supported nickel tetramer cluster (Ni4-ZSM-5). Hydrogenation of acetone to 2-propanol followed by dehydration to propene have been investigated as model reactions. In Ni4-ZSM-5, we observe reverse hydrogen spillover, whereby the Brønsted hydrogen migrates from the zeolite active site to the metal cluster. Consequently, the zeolite-supported metal cluster becomes electron-deficient, facilitating the hydrogenation reaction. In contrast, studies conducted on the dehydration reaction pathways indicate that the Brønsted acid catalysis in HZSM-5 is preferred over the metal catalyzed pathway in the Ni4-ZSM-5 system, again as a result of the electron-deficient nature of the metal species.

Influence of Cluster–Support Interactions on Reactivity of Size-Selected NbxOy Clusters

Size-selected niobium oxide nanoclusters (Nb3O5, Nb3O7, Nb4O7, and Nb4O10) were deposited at room temperature onto a Cu(111) surface and a thin film of Cu2O on Cu(111), and their interfacial electronic interactions and reactivity toward water dissociation were examined. These clusters were specifically chosen to elucidate the effects of the oxidation state of the metal centers; Nb3O5 and Nb4O7 are the reduced counterparts of Nb3O7 and Nb4O10, respectively. From two-photon photoemission spectroscopy (2PPE) measurements, we found that the work function increases upon cluster adsorption in all cases, indicating a negative interfacial dipole moment with the positive end pointing into the surface. The amount of increase was greater for the clusters with more metal centers and higher oxidation state. Further analysis with DFT calculations of the clusters on Cu(111) indicated that the reduced clusters donate electrons to the substrate, indicating that the intrinsic cluster dipole moment makes a larger contribution to the overall interfacial dipole moment than charge transfer. X-ray photoelectron spectroscopy (XPS) measurements showed that the Nb atoms of Nb3O7 and Nb4O10 are primarily Nb5+ on Cu(111), while for the reduced Nb3O5 and Nb4O7 clusters, a mixture of oxidation states was observed on Cu(111). Temperature-programmed desorption (TPD) experiments with D2O showed that water dissociation occurred on all systems except for the oxidized Nb3O7 and Nb4O10 clusters on the Cu2O film. A comparison of our XPS and TPD results suggests that Nb5+ cations associated with Nb═O terminal groups act as Lewis acid sites which are key for water binding and subsequent dissociation. TPD measurements of 2-propanol dehydration also show that the clusters active toward water dissociation are indeed acidic. DFT calculations of water dissociation on Nb3O7 support our TPD results, but the use of bulk Cu2O(111) as a model for the Cu2O film merits future scrutiny in terms of interfacial charge transfer. The combination of our experimental and theoretical results suggests that both Lewis acidity and metal reducibility are important for water dissociation.

Approach to the 1-propanol dehydration using an extractive distillation process with ethylene glycol

The extractive distillation process exploits the capacity of some chemicals to alter the relative volatility between the components of a mixture. In this way, a third component (called entrainer) may be added to an azeotropic binary mixture to break the azeotrope.This paper discusses the potential use of ethylene glycol as entrainer in a 1-propanol dehydration process by extractive distillation. First, the present work focuses on the acquisition of isobaric vapor–liquid equilibrium data of the ternary system 1-propanol+water+ethylene glycol system and the binaries systems 1-propanol+ethylene glycol and water+ethylene glycol. All measurements were done at 101.3kPa.The experimental data were correlated by the Wilson, NRTL and UNIQUAC local composition models in order to obtain a set of thermodynamic parameters. Finally, the extractive distillation process was simulated and later economically optimized with the aid of commercial software (Aspen Hysys®) using the previously obtained parameters of the NRTL model.

Solvothermal synthesis of nickel-tungsten sulfides for 2-propanol dehydration.

The bimetallic nickel-tungsten catalysts were prepared via solvothermal method. The X-ray Diffractometer (XRD) analysis revealed that the corresponding peaks at 14°, 34°, and 58° were for tungsten disulfide (WS2 ) hexagonal phase. The catalysts displayed different crystalline phase with nickel addition, and as an effect the WS2 surface area decreased from 74.7 to 2.0 m(2) g(--1) . In this sense, high-resolution transmission electron microscopy (HRTEM) showed the layers set in direction (002) with an onion-like morphology, and in the center of the particles there is a large amount of nickel contained with 6-8 layers covering it. The catalytic dehydration of 2-propanol was selective to propene in 100% at 250 °C for the sample with 0.7 of atomic ratio of Ni/Ni + W.