Conversion Of Isopropanol Research Articles

Synergy in Au-CuO Janus Structure for Catalytic Isopropanol Oxidative Dehydrogenation to Acetone.

The controlled oxidation of alcohols to the corresponding ketones or aldehydes via selective cleavage of the β-C-H bond of alcohols under mild conditions still remains a significant challenge. Although the metal/oxide interface is highly active and selective, the interfacial sites fall far behind the demand, due to the large and thick support. Herein, we successfully develop a unique Au-CuO Janus structure (average particle size=3.8 nm) with an ultrathin CuO layer (0.5 nm thickness) via a bimetal in situ activation and separation strategy. The resulting Au-CuO interfacial sites prominently enhance isopropanol adsorption and decrease the energy barrier of β-C-H bond scission from 1.44 to 0.01 eV due to the strong affinity between the O atom of CuO and the H atom of isopropanol, compared with Au sites alone, thereby achieving ultrahigh acetone selectivity (99.3 %) over 1.1 wt % AuCu0.75 /Al2 O3 at 100 °C and atmospheric pressure with 97.5 % isopropanol conversion. Furthermore, Au-CuO Janus structures supported on SiO2 , TiO2 or CeO2 exhibit remarkable catalytic performance, and great promotion in activity and acetone selectivity is achieved as well for other reducible oxides derived from Fe, Co, Ni and Mn. This study should help to develop strategies for maximized interfacial site construction and structure optimization for efficient β-C-H bond activation.

Aluminum‐Ligand Cooperative O−H Bond Activation Initiates Catalytic Transfer Hydrogenation

AbstractMolecular design ultimately furnishes improvements in performance over time, and this has been the case for Rh‐ and Ir‐based molecular catalysts currently used in transfer hydrogenation (TH) reactions for fine chemical synthesis. In this report, we describe a molecular pincer ligand Al catalyst for TH, (I2P2−)Al(THF)Cl (I2P=diiminopyridine; THF=tetrahydrofuran). The mechanism for TH is initiated by two successive Al‐ligand cooperative bond activations of the O−H bonds in two molecules of isopropanol (iPrOH) to afford six‐coordinate (H2I2P)Al(OiPr)2Cl. Stoichiometric chemical reactions and kinetic experiments suggest an ordered transition state, supported by polar solvents, for concerted hydride transfer from iPrO− to substrate. Metal‐ligand cooperative hydrogen bonding in a cyclic transition state is a likely support for the concerted hydride transfer event. The available data does not support involvement of an intermediate Al‐hydride in the TH. Proof‐of‐principle reactions including the conversion of isopropanol and benzophenone to acetone and diphenylmethanol with 90 % conversion in 1 h are described. The analogous hydride compound, (I2P2−)Al(THF)H, also cleaves the O−H bond in iPrOH to afford (HI2P−)Al(OiPr)H and (HI2P−)Al(OiPr)2, but no activity for catalytic TH was observed.

Theoretical analysis of the conversion of isopropyl alcohol

Theoretical analysis of the conversion of isopropyl alcohol

Direct conversion of isopropanol to C6+ branched compounds as high-octane gasoline blendstocks

An efficient one-pot process is developed to convert isopropanol to C6+ compounds with ideal branched-chain selectivity in the absence of H2, showing advantage in producing sustainable liquid fuel with a high-octane number.

Removal of Isopropanol by synergistic non-thermal plasma and photocatalyst

The dielectric barrier discharge (DBD) of non-thermal plasmas was combined with a self-made photocatalyst to remove isopropanol (IPA). Synthesis conditions for the novel photocatalyst, including calcination temperature and copper loading, were varied before photocatalysis to obtain at the optimal reaction efficiency. The effects of initial IPA concentration, oxygen content, and catalyst dosage were also observed. Finally, catalyst reusability was analyzed. X-ray photoelectron spectroscopy fitting revealed Ti, Cu, C, and O peaks in the synthesized catalyst. After a 60-min reaction with 100% oxygen as the carrying gas, nearly 100% of the IPA was converted. Overall, the optimal IPA conversion efficiency and acetone and carbon dioxide selectivity were achieved when the photocatalyst was synthesized at a calcination temperature of 550 °C and copper loading of 1.8%, along with a 100% oxygen carrying gas and a 3-mm discharge gap.

Effects of NiMoO4 impregnation on the catalytic activity of Cu3 (PO4)2 in the conversion of isopropanol

Hereby, we are describing the synthesis and characterization concerning acid -basic properties of catalysts containing varied amounts of NiMo (2-14 wt % of NiMoO 4 ) worn on copper orthophosphate whose its preparation was executed employing a co-precipitation method, to which we introduced the Nickel-Molydenum by impregnation with a porous volume at several stages, succeeded by calcination under air at a different temperature. The employed techniques for solids’ characterization were XRD to identify different phases, Nitrogen adsorption at-196°C. and catalytic conversion of isopropanol at different temperatures’ reaction ranging from 180 to 400 °C. The outcome revealed that the solids NiMo/CuP mainly consisted of copper phosphate Cu 3 (PO 4 ) 2 together with NiMoO 4 as minor phase. The NiMoO 4 crystallinity’s degree increases by increasing Nickel-Molydenum. It was discovered that the specific area (S BET ) of the studied system will slightly increase by the increase in NiMoO 4 content. The catalytic activity in isopropanol conversion which proceeds via dehydration yielding propene increases as a function of extent of loading.

Catalytic conversion of isopropyl alcohol on the heteropolic acid –titanium oxide system

A complex of modern physicochemical methods (X-ray phase analysis, low-temperature adsorption of nitrogen, scanning electron microscopy, element analysis)was used to studythe phase and texture properties of the phosphomolybdenum heteropoly acid–titanium oxide catalytic system. It was found that the optimal content of phosphomolybdenum heteropoly acid, which leads to an increase in the catalytic activity of titanium dioxide, is 7% wt.: the diisopropyl ether yield is higher,it reaches maximum values in a shorter period of time, and the samples are characterized by greater stability. It is shown that the textural characteristics of the specific surface area and dispersion are not the key factors responsible for the catalytic activity.It has been suggested that the activity of phosphomolybdenum heteropoly acid-containing samples is associated with the emergence of a new type of active centers that exhibit increased electron-donorproperties(terminal oxygen atoms of the outer frag-ments of octahedra М = О heteropolyacids). A drop in the catalytic activity of samples with a phosphomolyb-denum heteropoly acid content of more than 7% wt. associated with the formation of surface metaphosphoric acid and entails a decrease in active centers.

Rapid tool for evaluation of acido‐basic properties of solid catalysts at high reaction temperature conditions using 2-propanol and benzyl alcohol as probe molecules

We introduce a simple, fully automated and practical methodology to measure the relative activity of heterogeneous catalysts using probe molecules at operating temperature conditions employed in industrial processes. The applicability of this approach was demonstrated by studying the conversion and selectivity of model probe molecules, isopropanol and benzyl alcohol reactions at 250−450 °C, on γ-Al2O3, MM clay, ZnO and Fe2O3. Catalyst was packed into the bed of in-house fabricated bench-top unit, automated vapor generation unit was used to pass probe molecules through the bed, and the products were sampled by on-line GC. Amongst the probe molecules, benzyl alcohol was found to be more suitable for evaluation of surface acido‐basic properties, as it exhibited high conversion at all the studied temperatures, along with concomitant formation of toluene and benzaldehyde based on the relative presence of surface active sites, acidic sites yield toluene, and strong basic sites yield benzaldehyde.

Dehydration of isopropyl alcohol with activated carbon functionalized with Br- and S-containing reagents

Bromination of activated carbon GSGD was performed and active bromine-containing precursors were obtained, in which bromine is capable of being replaced by sulfur-containing functional groups. Bromination with liquid bromine and a solution of bromine in potassium bromide at room temperature leads to the introduction of 0.44–0.45 mmol g–1 of bromine into the surface layer of activated carbon. The treatment of brominated samples with sulfur-containing reagents with subsequent oxidation allows obtaining carbon samples that are catalytically active in the dehydration reaction of isopropyl alcohol in a gas phase. The temperature of complete conversion of isopropyl alcohol to propylene is a measure of catalytic activity. The concentration of sulfogroups in the prepared samples is up to 0.3 mol g–1. Thermogravimetry and thermoprogrammed desorption with mass spectrometric registration of products were used to study the thermal stability of modified activated carbon samples. The influence of the nature of brominating reagents, hydrolysis conditions and oxidation conditions on the structure, surface concentration of grafted S-containing groups and catalytic properties of the obtained materials was studied. Pre-bromination leads to an increase in the catalytic activity of activated carbon modified with sulfur-containing groups and the temperature of complete conversion of isopropyl alcohol to propylene decreases up to 400C depending on the concentration of sulfogroups.

Sulfonated nanoporous activated carbons for catalytic isopropyl alcohol dehydration

Sulfonation of nanoporous activated carbon (NAC) was performed in the different ways available within the synthetic organic chemistry armory for preparing solid acid catalysts of isopropyl alcohol dehydration (IDH). The sulfonated NACs, with from 0.15 to 1.0 mmol of sulfo groups per gram of NAC, have good catalytic performance. Sulfonated oligo- and poly(α-methylstyrene)s grafted on the oxidized NAC exhibited superior catalytic activity and high stability in the IDH reaction. Conversion of isopropyl alcohol to propene of about 100% was achieved with these catalysts at temperatures in the range of 140–170 °C. Most catalysts obtained are active in the IDH reaction; however, we observed that the propene yield depends on the method used for the NAC sulfonation.

1,3-Butadiene production from aqueous ethanol over ZnO/MgO-SiO2 catalysts: Insight into H2O effect on catalytic performance

A series of ZnO/MgO-SiO2 systems have been prepared and characterized by one-pass temperature-programmed desorption of CO2, NH3 and H2O, FTIR spectroscopy with adsorbed pyridine and CO2, temperature programmed surface reaction of ethanol and isopropanol, and reaction of isopropanol conversion. Effect of MgO:SiO2 ratio in the catalysts on catalytic performance in 1,3-butadiene production from aqueous ethanol have been investigated. The results indicate that hydrophilicity of ZnO/MgO-SiO2 are determined by MgO:SiO2 ratio, and chemisorption of water occurs preferably on Mg-containing sites. The presence of water in the initial ethanol leads to a decrease in formation of the CC coupling products. The hydrated sites formed in the interface of magnesia and silica remain active in the CC coupling reaction even in the presence of water. 1,3-Butadiene selectivity >60 % in the conversion of aqueous ethanol (80 vol%) is achieved in the presence of ZnO/MgO-SiO2 catalysts with the ratio of MgO:SiO2 = (1:1) and (3:1).

A novel study on CHEMCAD simulation of isopropyl alcohol dehydrogenation process development

Acetone is a product which is obtained via several processes. It is produced mainly by cumene hydroperoxide process. As an alternative process, acetone is obtained by isopropyl alcohol (IPA) dehydrogenation. The conversion of IPA to acetone is an endothermic gas-phase reaction which produces hydrogen as a byproduct. The process consists of an equilibrium reactor or kinetic reactor (EREA), a distillation column (SCDS), and a flash tank. As the fresh feed, liquid-phase IPA, combined with a recycle stream which contains slight amount of unseparated acetone, is vaporized and given into the equilibrium reactor. Reactor effluent is then cooled by two heat exchangers and pressurized by a compressor until unreacted IPA and formed acetone are liquidised. This stream is fed to a flash tank in order to separate the gas-phase hydrogen, which contains slight amount of acetone. The distillation column distinguishes the acetone from unreacted IPA. The distillate stream has an acetone purity over 99%. The bottoms stream, which consists of residual IPA and slight amount of acetone, is recycled back into the mixer. The purpose of this study is to improve the simulation of isopropyl alcohol (IPA) dehydrogenation process by using the ChemCad program in terms of industrial applications.

THE ACTIVITY OF MOLYBDENE-VANADIUM OXIDE CATALYSTS IN THE ISOPROPYL ALCOHOL CONVERSION REACTION

The activity of molybdenum-vanadium oxide catalysts in the conversion of isopropyl alcohol has been studied. It was found that acetone and propylene are the main products of the isopropyl alcohol conversion reaction. Studies have shown that the activity of binary molybdenumvanadium oxide catalysts depends both on the reaction conditions and on the atomic ratio of molybdenum to vanadium. It has been shown that molybdenum-vanadium oxide catalysts have a sufficiently high activity in the reaction of propylene and acetone formation and can be used for further modification in order to increase their catalytic activity. Keywords: isopropyl alcohol, acetone, propylene, binary catalysts, molybdenum oxide, vanadium oxide.

Gas-phase isopropanol degradation by nonthermal plasma combined with Mn-Cu/-Al2O3.

In this study, the dielectric barrier discharge (DBD) induced by nonthermal plasma (NTP) technology was used for isopropanol (IPA) degradation. IPA, intermediate, final product, and ozone concentrations were analyzed using GC-MS, carbon dioxide detector, and ozone detector. The experimental flow rate and concentration were fixed to 1 L/min and 1200 ppm ± 10%, respectively. Different reaction procedures were proposed for self-made metal catalyst combined with a plasma system (plasma alone and γ-Al2O3 combined with plasma, Cu (5 wt%)/γ-Al2O3 combined with plasma, Mn (3 wt%)-Cu (5 wt%)/γ-Al2O3 combined with plasma). In addition, the effect of the carrier gas oxygen content (0%, 20%, and 100%) on IPA conversion and intermediate and carbon dioxide selectivity was also investigated. The results revealed that the Mn (F)-Cu/γ-Al2O3 combined with plasma exhibited more efficient IPA conversion. In the 100% oxygen environment, the IPA conversion rate increased from 79.32 to 99.99%, and carbon dioxide selectivity increased from 3.82 to 50.23%. IPA was completely converted after 60 min of plasma treatment with the acetone selectivity, carbon dioxide selectivity, and tail ozone concentration of 26.71% ± 1.27%, 50.23% ± 0.56%, and 1761 ± 11 ppm, respectively. This study proved that the current single planar DBD configuration is an effective advanced treatment technology for the decomposition of VOCs.

Phosphorus containing carbon (submicron)fibers as efficient acid catalysts

Porous carbon fibers catalysts have been prepared by electrospinning of Alcell lignin, a green carbon precursor, which could be obtained as by-product in wood-to-ethanol biorefineries. The addition of H3PO4, a well-known chemical activation agent, to the electrospinning lignin solutions, at different mass ratios and the use of different carbonization temperatures, between 500 and 1600 °C, were analyzed in order to obtain carbon fibers with a large variety of porosity and chemical surface properties. Isopropanol decomposition was used as a catalytic test. Phosphorus-containing carbon fibers showed acid character and high catalytic activity, achieving propylene selectivity of 100 % under inert atmosphere. However, the use of air atmosphere increases the isopropanol conversion but produces the formation of acetone, via oxidative dehydrogenation, at low temperatures (∼20 %). Ethanol and methanol decomposition were also evaluated in air stream for the most active phosphorus-containing carbon catalyst, showing improved alcohol conversions with minimal gasification of the carbon fibers. These results confirmed that phosphorus-containing carbon fibers prepared by electrospinning of lignin solutions were excellent catalysts for alcohol dehydration reactions.

Selective dehydrogenation of isopropanol on carbonized metal–organic frameworks

Alcohol dehydrogenation to carbonyl compounds and hydrogen (H2) gas offers a green and sustainable method for producing H2 and the synthesis of various pharmaceuticals and fine chemicals. However, it is a challenge to acquire remarkable selectivity toward carbonyl products. Herein, CuO@C catalyst displays high dehydrogenation over dehydration reaction for isopropanol. CuO@C core–shell was synthesized from the carbonization of metal–organic frameworks (MOFs) via a single step without the need for incorporating an external source of carbon. CuO@C showed high selectivity (100%) and increased conversion (100%) of isopropanol to acetone and hydrogen via dehydrogenation. It exhibited high stability under the reactant flow for a long time and reusability for several cycles. A mechanism of the dehydrogenation was also highlighted using different analytical methods, including X-ray diffraction (XRD), electron diffraction (ED), Fourier transform infrared (FT-IR), and high-resolution transmission electron microscopy (HR-TEM).

Transition from 2D to 3D SBA-15 by High-Temperature Fluoride Addition and its Impact on the Surface Reactivity Probed by Isopropanol Conversion.

A systematic variation of the SBA‐15 synthesis conditions and their impact on the structural and chemical characteristics are reported. An incremental alteration of the hydrothermal aging temperature and time was used to induce changes of the highly ordered SBA‐15 structure. Any effects on the total surface area, mesopores size, micropore contributions, and pore connectivity are amplified by a combined incremental increase of the NH4F concentration. Based on changes of the unit‐cell parameter as a function of the mesopore size, and a feature in the low‐angle XRD pattern, useful descriptors for the disorder of the corresponding SBA‐15 are identified. An additional analysis of the Brunauer–Emmett–Teller (BET) surface area and pore size distributions enables investigations of the structural integrity of the material. This systematic approach allows the identification of coherencies between the evolution of physical SBA‐15 properties. The obtained correlations of the surface and structural characteristics allow the discrimination between highly ordered 2D SBA‐15, disordered 3D SBA‐15, and highly nonuniform silica fractions with mainly amorphous character. The fluoride‐induced disintegration of the silica structure under hydrothermal conditions was also verified by TEM. A direct influence of the structural adaption on the chemical properties of the surface was demonstrated by isopropanol conversion and H/D exchange monitored by FTIR analysis as sensitive probes for acid and redox active surface sites.

Highly Active Catalysts for the Dehydration of Isopropanol

Due to the high costs and low selectivity associated with the production of propylene, new routes for its synthesis are being sought. Dehydration has been widely investigated in this field, but, thus far, no study has produced efficient results for isopropanol. Vanadium-zirconia catalysts have been shown to be effective for the dehydration of ethanol. Therefore, we investigated the activity of such catalysts in the dehydration of isopropanol. The catalysts were synthetized on a SBA-15 base, supplemented with zirconia or combined zirconia and vanadium. Tests were conducted in a continuous flow reactor at 150–300 °C. Samples were analyzed using a gas chromatograph. The most active catalyst showed 96% conversion with 100% selectivity to propylene. XRD, SEM and Raman spectroscopy analyses revealed that as the vanadium content increases, the pore size of the catalyst decreases and both isopropanol conversion and propylene selectivity are reduced. Thus, without the addition of vanadium, the Zr-SBA-15 catalyst appears to be suitable for the dehydration of isopropanol to propylene.

Direct formation of LaFeO3/MCM−41 nanocomposite catalysts and their catalytic reactivity for conversion of isopropanol

Direct formation of 3–30% (w/w) LaFeO3/MCM−41, nanocomposite catalysts were performed by a sol−gel process, followed by calcination at 550 and 750 °C. The nanocomposites were characterized through different techniques including LAXRD, WAXRD, EDX, simultaneous TG−DTA, ATR−FTIR, nitrogen adsorption/desorption, and TEM. The nanocomposites featured high surface areas (up to 1000 m2/g) and enhanced thermal stability. The direct formation method led to nanodispersion and size confinement of LaFeO3 in MCM−41 mesopores. The nanocomposites showed very high catalytic activity for isopropanol conversion, whereas their parent materials (blank MCM-41 or bulk LaFeO3) were totally inactive under the same reaction conditions. Thus, nanocomposite catalysts with low loading ratios and low calcination temperature produced pure dehydration product (propene) with very high conversion and total selectivity. Nanocomposite catalysts with high loading ratios and high calcination temperature produced an appreciable amount of the dehydrogenation product (acetone) as well as the dehydration products. Moreover, high loading ratios at high reaction temperatures in air atmosphere led to the formation of oxidation products. The different reactivities of the nanocomposite catalysts were discussed and correlated to their nanostructure, in terms of enhancing of the mesoporous textures with surface acidity, oxidation ability and thermal stability.

The interplay between surface facet and reconstruction on isopropanol conversion over SrTiO3 nanocrystals

Strontium titanate (SrTiO3) is an extensively investigated perovskite for various applications due to its optical, electrical and chemical properties. To gain an in-depth understanding of the active sites involved in heterogeneous catalysis over the broadly used SrTiO3 (STO), we studied a model reaction, isopropanol conversion, on three differently shape-controlled nanocrystals: cube, truncated cube and dodecahedra. SEM, XRD and XPS confirmed the morphology, phase and composition of STO shapes. Low energy ion scattering (LEIS) revealed the occurrence of surface reconstruction over STO shapes during O2 pretreatment at different temperatures. Based on the catalytic activities, scanning transmission electron microscopy images and density functional theory calculations, the step sites on STO derived from surface reconstruction were proposed to be the active sites for isopropanol conversion. This was further confirmed by steady state isotopic kinetic analysis (SSITKA) which demonstrated similar intrinsic turnover frequencies (TOFs) for the differently reconstructed STO shapes. It is concluded that the crystal facets impose an indirect effect on the catalysis of STO via controlling the degrees of surface reconstruction: the less stable STO (1 1 0) facet (dodecahedra) leads to more step sites after reconstruction and hence higher overall reaction rate than the more stable (1 0 0) facet (cube). This work highlights the important interplay between the crystal facet and surface reconstruction in controlling the nature and density of active sties and thus catalysis over complex oxides.