Carbon Monoxide Hydrogenation Reaction Research Articles

Synergistic effect of Zr and K promoters on iron-based catalysts in CO hydrogenation reaction

There is a growing demand for decreasing fossil fuel usage. That being said, we should move toward renewable and sustainable energy sources. Iron-based catalysts are usually employed in this route. In this work, an incipient impregnation process was used for preparing four γ-Al2O3 supported iron-based catalysts with different weight percents including 20Fe/5Cu/γ-Al2O3, 20Fe/5Cu/2K/γ-Al2O3, 20Fe/5Cu/3Zr/γ-Al2O3 and 20Fe/5Cu/1.5Zr/1K/γ-Al2O3 under the pressure of 20 atm, the temperature of 285 °C, H2 to CO ratio of one, and a gas hourly space velocity of 2 NL/ (h. gCat). BET, FE-SEM, XRD, H2-TPR, ICP, and TEM techniques were used to determine the characteristics of the catalysts, while gas chromatography results were used to determine CO conversion and product selectivity. Due to the synergistic effect of the two promoters, the doubly-promoted catalyst exhibited a C5+ selectivity of 64.2 %, surpassing both the Fe/Cu/γ-Al2O3 catalyst and the singly-promoted catalysts. This result highlights the enhanced performance of the doubly-promoted catalyst. Compared to the other catalysts prepared, the doubly-promoted catalyst demonstrated a higher carbon monoxide (CO) conversion rate of 67.7 % and yield of 43.5 %. Moreover, The results demonstrate the significant impact of Zr and K promoters of the synthesized Fe-based catalysts on hydrocarbon product distribution.

Modeling the Effect of Magnesia Nanoparticles on CO Hydrogenation to Light Olefins in a Continuous Flow Reactor Using Fine Gaussian Support Vector Machine

The effect of utilising energy derived from fossil sources on the environment has aroused research interest in alternative and sustainable energy sources. Synthesis gas, a mixture of carbon monoxide (CO) and hydrogen can be used as starting materials in hydrogenation reactions to produce chemical intermediates that can be used in various processes. This study investigates the robustness of applying a fine Gaussian support vector machine algorithm for predicting light olefins from catalytic CO hydrogenation using magnesia nanoparticles-based catalysts. The datasets obtained from the CO hydrogenation reaction consist of input parameters such as magnesia nanoparticles contents, reaction temperature, and reactor pressure, and the output parameters which include CO conversions and the selectivity of light olefins (CH4, C2H6, C2H4 C3H8, C4H8, and C3H6). The dataset was trained and employed for the prediction of the light olefins using a support vector machine with an inbuilt Fine Gaussian Kernel function. The performance of the support vector machine was evaluated using the coefficient of determination (R2), root mean squared error (RMSE), mean square error (MSE), and the mean absolute error (MAE). The support vector machine showed significant potential in the prediction of CO conversion, CH4 selectivity, C2H6 selectivity, and C2H4 selectivity as indicated by R2 of 0.770, 0.800, 0.730, and 0.930, respectively. While less predictive performance was obtained for the prediction of C3H8 selectivity, C4H8 selectivity and C3H6 selectivity as indicated by R2 of 0.630, 0.610, and 0.320, respectively.

Effect of the Polymer Molecular Weight on the Catalytic Properties of Polyacrylonitrile-Based Cobalt Composites in the Carbon Monoxide Hydrogenation Reaction

The effect of the polymer molecular weight on the catalytic properties of cobalt composites based on polyacrylonitrile (PAN) in the carbon monoxide hydrogenation reaction has been studied. It has been found that the CO conversion tends to 100% in the presence of any of the systems. It has been revealed that for the system based on PAN with a higher molecular weight, a quantitative CO conversion is observed at a lower temperature. It has been assumed that during the synthesis of the composite materials, the active phases undergo encapsulation differently. X-ray diffraction (XRD) analysis has revealed that the formation of metallic cobalt particles occurs regardless of molecular weight.

Carbon Monoxide Hydrogenation on Ice Surfaces.

We have performed density functional calculations to investigate the carbon monoxide hydrogenation reaction (H+CO→HCO), which is important in interstellar clouds. We found that the activation energy of the reaction on amorphous ice is lower than that on crystalline ice. In the course of this study, we demonstrated that it is roughly possible to use the excitation energy of the reactant molecule (CO) in place of the activation energy. This relationship holds also for small water clusters at the CCSD level of calculation and the two-layer-level ONIOM (CCSD : X3LYP) calculation. Generally, since it is computationally demanding to estimate activation energies of chemical reactions in a circumstance of many water molecules, this relationship enables one to determine the activation energy of this reaction on ice surfaces from the knowledge of the excitation energy of CO only. Incorporating quantum-tunneling effects, we discuss the reaction rate on ice surfaces. Our estimate that the reaction rate on amorphous ice is almost twice as large as that on crystalline ice is qualitatively consistent with the experimental evidence reported by Hidaka et al. [Chem. Phys. Lett., 2008, 456, 36.].

The formation of formaldehyde via the carbon monoxide hydrogenation catalyzed by the HSbF6 superacid

The mechanism of the carbon monoxide hydrogenation reaction yielding formaldehyde with the assistance of the HSbF6 (HF/SbF5) superacid catalyst was investigated theoretically using ab initio MP2 and CCSD(T) methods and the aug-cc-pVDZ basis set (the effects of surrounding solvent molecules were approximated by employing the polarized continuum solvation model). The detailed mechanisms in both gas and liquid (anhydrous HF) phases proceeding either along the concerted path or according to the stepwise route were analyzed and discussed. The most important findings include the observation that the activation barriers calculated for both paths considered are significantly reduced (by 67%) in comparison with the uncatalyzed syngas hydrogenation process. The estimated barrier heights for the concerted mechanism (27.2 kcal/mol) and the stepwise mechanism (0.8 and 26.1 kcal/mol) operating in the liquid phase confirm that the fluoroantimonic acid performs much better as a catalyst in the CO + H2 → H2CO process than other strong acids, thus indicating that the HSbF6 superacid effectively reduces the activation barriers to render the carbon monoxide hydrogenation plausible.

Hydrogénation du Monoxyde de Carbone II - Influence du support et du cesium sur les propriétés du Nickel-Molybdène

The selectivity for alcohols formation in the carbon monoxide hydrogenation reaction on nickel molybdenum catalysts increased when zinc oxide was used as a support, where it reached 50%. The same trend was observed when an alkaline metal such as cesium was added to the catalyst. Moreover when the surface area of the zinc support was increased from 10 to 80 m2·g−1 the selectivity was multiplied by 20 with a selectivity for alcohol formation still greater than 70% after 20 hours time on stream.

Influence of the Cobalt Particle Size in the CO Hydrogenation Reaction Studied by In Situ X-Ray Absorption Spectroscopy

The influence of particle size in the carbon monoxide hydrogenation reaction has been studied using cobalt nanoparticles (NPs) with narrow size distribution prepared from colloidal chemistry. The surfactant covering the NPs after synthesis could be removed by heating to 200-270 degrees C in H(2). Soft X-ray absorption spectroscopy was performed using a gas flow cell under reaction conditions of H(2) and CO at atmospheric pressure. Flow of pure hydrogen at 350 degrees C removed the protecting surfactant layer and reduced the NPs from oxidized to metallic. The NPs remained metallic during the methanation reaction with their surface covered by CO. The methanation turnover frequency of silica-supported NPs was found to decrease with diameter below 10 nm, whereas the reaction activation energy was found to be independent of NP size. H-D exchange experiments indicated that it is the dissociation of H(2) that is responsible for the observed decrease in activity with size.

Catalytic properties of potassium-or lanthanum-promoted Co/γ-Al2O3 catalysts in carbon monoxide hydrogenation

The effects of potassium or lanthanum additives on the catalytic properties of alumina-supported cobalt catalysts were examined through carbon monoxide hydrogenation reaction. The catalysts were characterized by hydrogen or carbon monoxide chemisorption, oxygen titration, and temperature-programmed desorption. The reactions were carried out at 270 °C and atmospheric pressure. When a small amount of potassium was added to alumina-supported cobalt catalysts, the amount of hydrogen adsorption decreased more significantly than that of carbon monoxide adsorption, and the extent of reduction also decreased. With the addition of potassium, the overall carbon monoxide conversion decreased, while the selectivity to higher hydrocarbon and olefin increased. The effect of lanthanum on activity and selectivity in carbon monoxide hydrogenation was less significant than the effect of potassium. Temperature-programmed desorption showed that the presence of additives changed the adsorbed state of CO on cobalt.

Cobalt/manganese oxide catalysts: Use of chromium promoters for long chain hydrocarbon production

Co/MnO (1:1) catalysts, active for the carbon monoxide hydrogenation reaction, were modified with chromium promoters (2–25% by mass; relative to Co). Significant changes in hydrocarbon selectivities were observed consistent with an increase in chain propagation ( α 2 increased from 0.90 to 0.94 ). Studies on the effect of operating pressure, temperature and GHSV led to an optimization of medium wax yield for a selected level of chromium. Bulk and surface characterization techniques were used to investigate the catalyst formulation and to determine the origin (s) of the modified catalytic behaviour.

Effect of chromium addition on the behaviour of iron/activated carbon catalysts for carbon monoxide hydrogenation

To study the effect of chromium addition to iron/active carbon catalysts in the carbon monoxide hydrogenation reaction at atmospheric pressure, five FeCr/C catalysts were prepared with a range of Cr/Fe atomic ratii. Three samples were prepared by coadsorption of the respective nitrates and the other two by successive adsorption. Catalysts were characterized by carbon monoxide chemisorption at 298 K and their catalytic activity was studied in differential conditions after reduction in hydrogen at 673 K. Both the irreversible carbon monoxide chemisorption and the catalytic activity of the samples decrease with increasing chromium content, this decrease being more important in the catalyst prepared by successive adsorption, with the chromium precursor added after adsorption of iron. Chromium favors methane production without modifying the selectivity towards alkenes. These results are interpreted on the basis of a diluent effect of chromium, which results in a decrease in the amount of surface-reduced iron sites.

Carbon dioxide hydrogenation over nickel/zirconia catalysts from amorphous precursors: on the mechanism of methane formation

An amorphous Ni{sub 64}Zr{sub 36} alloy is used as a precursor for a carbon dioxide hydrogenation catalyst. Upon exposure to CO{sub 2} hydrogenation conditions, the glassy metal is partly transformed into crystalline metallic nickel particles and less well-ordered zirconium dioxide. A conventional Ni/ZrO{sub 2} catalyst, which was synthesized by coprecipitation and calcination of the amorphous precipitate, served as a reference. The as-prepared catalyst exhibits a very similar catalytic behavior to the alloy-derived catalyst. The structural and chemical changes are characterized by gas adsorption, X-ray diffraction, and thermal analysis. In CO{sub 2} hydrogenations over these catalysts, methane is almost exclusively produced, and traces of ethane are formed besides, as evidenced by gas chromatography. To study the origins of this selectivity behavior, in situ diffuse reflectance FTIR spectroscopy has been applied. Surface species in carbon dioxide as well as carbon monoxide hydrogenation reactions are correlated with the formation of gas-phase products. CO{sub 2}/H{sub 2} mixtures rapidly yield surface formate as the immediate precursor of the methane product on the coprecipitated catalyst. Doubly and singly bound adsorbed CO is detected besides; doubly bound CO is observed to originate from surface formate. In CO/H{sub 2} reactions, higher saturated hydrocarbons are produced besides methane. Themore » formation of these products proceeds from singly bound adsorbed CO via a dissociative mechanism. The respective hydrogenation steps are discussed in detail in a corresponding reaction scheme.« less

Study of iron/mordenite catalysts by Mössbauer and ferromagnetic resonance spectroscopy for carbon monoxide hydrogenation

Iron was loaded on mordenites with varying cation type and degree of dealumination, and their catalytic properties were characterized by means of Mössbauer and ferromagnetic resonance spectroscopy and carbon monoxide hydrogenation as a probe reaction. When iron was impregnated on mordenites, it was found that about 1.2 wt.-% of iron existed as ion-exchanged cationic iron in the oxide or hydroxide form. Iron oxide particles formed after calcination at 450°C showed a wide distribution in their size, ranging from cluster-sized superparamagnetic oxide to large particles of α-Fe2O3. After reduction at 450°C, iron oxide particles were sintered to be reduced to bimodally distributed metallic iron particles. Small iron particles generated on hydrogen-form mordenites are believed to be stabilized by some defect sites generated by dealumination of mordenite. On sodium-mordenite, extremely small and uniform iron clusters were generated because free sodium ions, which had been detached from the framework by previous ion exchange with impregnated iron ions, promoted reduction of ion-exchanged cationic irons. The result was applied to reduce ion-exchanged iron (FeNaM10) by injecting a high concentration of sodium ions into the pores of mordenite and about 27% of the iron was able to be reduced upon treatment in hydrogen gas at 450°C. These iron clusters showed lower activity but higher selectivity toward alkenes in the carbon monoxide hydrogenation reaction than conventional impregnated catalysts.

Scanning Electron Microscopy of a supported molten salt CuC1-KCl/SiO2catalyst

Carbon monoxide hydrogenation reactions catalyzed by heterogeneous catalysts are of significant industrial importance. Most methanol synthesis catalysts contain copper in synergism with ZnO and other metal oxide components. The chemical constitution and physical form of the copper phase in the working alcohol synthesis catalyst has been the subject of considerable concern. Recent NMR and x-ray, spectroscopic and microscopic investigation of alkali metal-promoted copper catalysts confirm earlier reports that the copper phase in methanol synthesis catalysts is a mixture of Cu(O) and Cu(I). Stabilization of a dispersion of Cu(I) is imperative for high activity.

Promoting effects of lithium on Pd/CeO2 catalysts in carbon monoxide-hydrogen reactions: Chemical trapping and temperature-programmed desorption studies

At a low percentage, lithium (0.15%) increases the methanol activity and selectivity of a Pd/CeO 2 catalyst. Higher lithium loadings result in the appearance of ethanol (23.4% ethanol selectivity on 3% Pd-1% Li/CeO 2) but with a decreased overall catalytic activity. The maximum amounts of surface formyl species and of adsorbed carbon monoxide correspond to the most active methanol synthesis catalyst (3% Pd-0.15% Li/CeO 2). These results suggest that lithium can stabilize adsorbed carbon monoxide and surface formyl species. An increase in the temperature of desorption of carbon monoxide after carbon monoxide-hydrogen reaction (from 470 to 590 K) is attributed to an interaction between adsorbed CO and Li +. This interaction can both favour carbon monoxide dissociation and carbon monoxide insertion reactions. Temperature-programmed desorption after ethanol adsorption was performed and a mechanism of ethanol formation is proposed.

Morphology and catalytic activity of FeRe bimetallic catalysts supported on silica: II. Catalytic activity in the carbon monoxide—hydrogen reaction

The activity and selectivity of Fe Re and Fe Ir catalysts with 100, 90, 50, 0 and 100, 50, 16.7, 0 atom-% iron content, respectively, and Ni Re catalysts with 50 atom-% Ni content, all with 2 wt.-% total metal loading supported on silica, in the hydrogenation of carbon monoxide were investigated. The Fe Re and Fe Ir catalysts showed a maximum in catalytic activity and their selectivity resembled more or less that observed on pure iron. Addition of potassium to the Fe Re catalyst diminished the activity but C 2+ and olefin selectivities were shifted toward that observed on iron. In contrast to the Fe Re system, Ni Re/SiO2 was reduced to a greater extent than Ni/SiO, but in both instances stabilization of the metal dispersion by rhenium was also observed. The reaction mechanism on the bimetallic catalysts largely depends on the type of the constituent atoms. On Fe Re and Ni Re catalysts inactive carbide formation is suppressed compared with that for pure nickel and iron. The main difference however, lies in the amount of the weakly bound hydrogen measured by temperature-programmed reduction, which is hardly altered in the Ni and Ni Re system, but markedly increases when rhenium is added to iron. The Fe Ir catalysts resemble the Ni Re samples.

Carbon-supported, [alkali metal] [Fe 2Mn(CO) 12]-derived catalysts : Adsorption properties and catalytic behavior in carbon monoxide hydrogenation

The properties of carbon-supported Fe, Fe Mn, and alkali metal (AM) Fe Mn catalysts derived from stoichiometric carbonyl clusters have been characterized by hydrogen and carbon monoxide adsorption, integral heat of adsorption measurements on both fresh and used catalysts, and kinetic studies of the carbon monoxide hydrogenation reaction. The precursors employed were Fe 3(CO) 12, N(C 2H 5) 4[Fe 2Mn(CO) 12] and AM[Fe 2Mn(CO) 12], with AM representing Li, Na, K, Rb or Cs so that the entire family of AM promoters was studied under identical conditions. The support was a microporous carbon prepared from olive pits activated in carbon dioxide which had a BET surface area of 876 m 2/g. Nitrogen adsorption at 77 K and carbon dioxide adsorption at 273 K gave quite similar adsorbed amounts for all the iron-containing samples. High iron dispersion was attained with the Fe 3(CO) 12 cluster but addition of manganese reduced carbon monoxide chemisorption, and further addition of an AM to a sample cluster resulted in a smaller additional decrease except for the Na[Fe 2Mn(CO) 12] precursor, which gave the highest uptake among the AM-promoted catalysts. Importantly, it is shown that active catalysts can be obtained without a prereduction step when these carbon-supported clusters are handled under anaerobic conditions, and high selectivities to light alkenes were attained with the promoted samples. The integral carbon monoxide heat of adsorption at 300 K on the supported, manganese-promoted iron crystallites was consistent with recent values for bulk Mn Fe catalysts, and the highest Q ad value was obtained by the further addition of potassium to the Mn Fe catalyst.

Temperature-programmed desorption studies on Pd/CeO 2 after methanol and formic acid adsorption and carbon monoxide—hydrogen reaction

Temperature-programmed desorption (TPD) after methanol and formic acid adsorption and CO&z.sbnd;H 2 reaction were studied on palladium catalysts. No difference in the nature of the products after decomposition of methanol on 3% Pd/SiO 2 and 3% Pd/CeO 2 was found. Both catalysts decompose methanol into CO+H 2. After adsorption of formic acid on CeO 2 alone, methanol was desorbed with a maximum at 540–550 K. This result can be interpreted by possible hydrogenation of formate species into methanol. On the other hand, no methanol was observed after adsorption of formic acid on 3% Pd/CeO 2 (methane was desorbed with a maximum at 545 K). Two peaks of methanol desorption were found after CO&z.sbnd;H 2 reaction on CeO 2 at 383 and 535 K. The first could be formed after methoxy hydrogenation and the second may be due to hydrogenation of formate species. TPD after CO&z.sbnd;H 2 reaction on 3% Pd/CeO 2 gave results similar to those found after methanol adsorption. These results suggest that formyl species are involved in methanol synthesis on Pd/CeO 2 catalyst, whereas on CeO 2 formate species could be the main intermediate.

Characterization of cobalt clusters nucleated on CoNay by ferromagnetic resonance spectroscopy and carbon monoxide hydrogenation

Cobalt clusters prepared by reducing CoNaY with hydrogen at 500°C were characterized by ferromagnetic resonance (FMR) spectroscopy and carbon monoxide hydrogenation as a probe reaction. Two different amounts of cobalt ions in CoNaY (4.5 and 7 wt.% cobalt loading, Co-IE-4.5 and Co-IE-7) were prepared by an ion-exchange method and NaY of 10 wt.% of cobalt loading (Co-IM-10) was prepared by the incipient wetness method in order to study the effect of cobalt loadings on the location and size of cobalt clusters produced. FMR characterization of Co-IE-4.5 after various pretreatments and different catalytic properties of Co-IE-4.5, Co-IE-7 and Co-IM-10 in the carbon monoxide hydrogenation reaction suggested that cobalt clusters of size between 5Åand 13Åwhich can not be sintered at 500°C were prepared by controlling the reduction period and the concentration of cobalt ions to be reduced in CoNaY.

Study of relative stabilities of the intermediates in catalytic carbon monoxide hydrogenation reactions: ab initio calculations on the model compounds [Fe(CO)2(PH3)2H2], [Fe(CO)2(PH3)2(CHO)H], [Fe(CO)2(PH3)2(CH2O)], and [Fe(CO)(PH3)2(CHO)2

Ab initio calculations have been performed on the model compounds [Fe(CO)2(PH3)2H2], [Fe(CO)2(PH3)2(CHO)H], [Fe(CO)2(PH3)2(CH2O)], and [Fe(CO)(PH3)2(CHO)2] to investigate the relative stabilities of the intermediates in catalytic carbon monoxide hydrogenation reactions. The results suggest that the formaldehyde compound can be obtained via insertion of CO into the Fe–H bond and subsequent rearrangement of the hydrido–formyl intermediate, in agreement with a proposed mechanism of the Fischer–Tropsch synthesis. Partial geometry optimizations obtained by gradient calculations show that the migration of one hydrogen of the co-ordinated formaldehyde in [Fe(CO)2(PH3)2(CH2O)] to iron to give [Fe(CO)2(PH3)2(CHO)H] is not allowed, while the migration of the same hydrogen to an adjacent CO to yield [Fe(CO)(PH3)2(CHO)2] is energetically favoured.

Morphology and surface defects of zinc oxide

Samples of zinc oxide prepared from different sources do not show the same type of selectivity for hydrogenation of carbon monoxide due to creation of various types of active sites on the surface. It is reasonable to expect that there may be some correlation between the nature of surface defects or active sites and morphology of zinc oxide crystallites. In the present investigation, the surface defects have been characterized by electrical conductivity measurement and the morphology has been studied by electron microscopy, electron diffraction, X-ray diffraction, and NIR spectroscopy. It has been concluded that the surface of zinc oxide prepared from carbonate consists of all types of planes, whereas basal planes predominate in zinc oxide prepared from oxalate and pigment. Because of this, the surface of zinc oxide from carbonate is less reduced than the other two varieties of zinc oxide in the presence of hydrogen under conditions similar to carbon monoxide hydrogenation reaction. This leads to variations in selectivity.