Catalytic Hydrogenation Of Carbon Monoxide Research Articles

Theoretical prediction of the catalytic efficiency of non-metalated pincer-like phosphorus compounds for the hydrogenation of carbon-monoxide with ammonia-borane

The catalytic hydrogenation of carbon monoxide (CO) with ammonia-borane (NH3BH3) using a series of phosphorus compounds (1) has been explored computationally. The formation of an active phosphorus compound (1-H) via the subsequent transfer of protic and hydridic hydrogens from NH3BH3 to 1 is the initiation step. The newly formed catalyst (1-H) further carries out the conversion of CO to formaldehyde (HCHO) to methanol (MeOH). The impact of ONO-ligand substitution and ONO-framework modification on the catalytic efficiency is also studied. The catalytic efficiencies of the phosphorus compounds have been compared based on the calculated activation barriers of rate-determining step (RDS).

Mechanochemical effects underlying the mechanically activated catalytic hydrogenation of carbon monoxide

In this work, we highlight and measure the intensity of mechanochemical effects at work in the hydrogenation of carbon monoxide by comparing the activity of a supported Co–Fe catalyst subjected, respectively, to ball milling and simple powder agitation. Paying due regard to the discontinuous nature of ball milling, we show that mechanochemical hydrogenation proceeds at significantly higher rate and disclose its connection with individual impacts. Experimental evidence suggests that the enhanced catalytic activity we observe can be ascribed to local processes affecting the amount of powder that gets involved in individual impacts.

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.

The Active Nature of Crystal MoS2 for Converting Sulfur‐Containing Syngas

AbstractMolybdenum disulfides are attractive sulfur‐tolerant catalysts suitable for the direct conversion of sulfur‐containing syngas, which avoids the expensive step of the deep desulfurization. However, the catalytic activity of MoS2‐based catalysts is relatively low. To improve the activity, previous works have focused on modifying MoS2 with various promoters and supports, but the structural aspects are largely overlooked. In this work, we investigated the active nature of the MoS2‐based catalysts for the catalytic hydrogenation of carbon monoxide. Thus, the bulk MoS2 with varied crystallite sizes was synthesized by the hydrothermal and the thermal decomposition methods. The catalysts before and after catalytic tests were characterized by in‐situ X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission electron microscope techniques. The CO hydrogenation under low‐temperature methanation conditions (The syngas with a H2/CO=2 and 40.0 ppm H2S, T=360 °C, and P=2 MPa) was applied to evaluate MoS2 as a catalyst for converting syngas. The catalytic results indicate that the MoS2 with smaller crystallite sizes exhibited a higher CO conversion. By correlating the structural propriety with the catalytic activity, a hexagonal‐prim‐shaped model was developed to describe different sites on the MoS2 crystallite. Based on this model, the activity of different active sites on the bulk MoS2 for CO hydrogenation decreased in the order of rim sites > edge sites ≫ basal sites. The highest catalytic activity over the bulk MoS2 with smallest particles was attributed to the highest exposure of the rim sites.

Evidence of Structure Sensitivity in the Fischer–Tropsch Reaction on Model Cobalt Nanoparticles by Time‐Resolved Chemical Transient Kinetics

AbstractThe Fischer–Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer–Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non‐steady‐state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H2/CO=2. Large differences in carbon coverage (ΘC) were observed for the two catalysts: the 4.3 nm Co catalyst has a ΘC less than one while the 9.5 nm Co catalyst supports a ΘC greater than two. The monomer units present on the surface during reaction are identified as single carbon species for both sizes of Co nanoparticles, and the major CO dissociation site is identified as the B5‐B geometry. The difference in activity of Co nanoparticles was found to be a result of the structure sensitivity caused by the loss of these specific types of sites at smaller nanoparticle sizes.

Evidence of Structure Sensitivity in the Fischer-Tropsch Reaction on Model Cobalt Nanoparticles by Time-Resolved Chemical Transient Kinetics.

The Fischer-Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer-Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non-steady-state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H2 /CO=2. Large differences in carbon coverage (ΘC ) were observed for the two catalysts: the 4.3 nm Co catalyst has a ΘC less than one while the 9.5 nm Co catalyst supports a ΘC greater than two. The monomer units present on the surface during reaction are identified as single carbon species for both sizes of Co nanoparticles, and the major CO dissociation site is identified as the B5 -B geometry. The difference in activity of Co nanoparticles was found to be a result of the structure sensitivity caused by the loss of these specific types of sites at smaller nanoparticle sizes.

Catalytic hydrogenation of carbon monoxide over nanostructured perovskite-like gadolinium and strontium ferrites

The catalytic properties of perovskite-like ferrites (An + 1BnO3n + 1, where n = 1, 2, 3, …, ∞; A = Gd, Sr; and B = Fe) synthesized via ceramic and sol-gel technology in the hydrogenation of carbon monoxide are studied. The interrelation between catalytic activity, selectivity to olefins and synthetic methods for complex oxide preparation, the number of perovskite layers, crystallite size, composition, and the valence state of iron is established.

Product distribution change in the early stages of carbon monoxide hydrogenation over cobalt magnesium Fischer-Tropsch catalyst

The catalytic hydrogenation of carbon monoxide, known as the Fischer-Tropsch process, is a technologically important, complex multipath reaction which produces long chain hydrocarbons. In order to access the initial kinetics and the mechanism, we developed a reactor that provides information under non-steady state conditions. We tested a CoMgO catalyst and monitored the initial product formation within 2s of exposure to CO as well as the time dependence of high molecular weight products (in a 60s window) and found drastic changes in the product selectivity. The probability for forming branched isomers (C4 and C5) peaks in the first 25s, and within that time frame no unsaturated products were detected. The subsequent decline (at ∼35 to 40s) of branched isomers coincides with the detection of olefins (fromC2 to C5) and the change in carbon coverage at the surface of the catalyst. This indicates a change in the reaction pathway.

Size-Dependent Activity and Selectivity of Fe/MCF-17 in the Catalytic Hydrogenation of Carbon Monoxide Using Fe(0) Nanoparticles as Precursors

Monodisperse Fe(0) nanoparticles with diameters between 1.8 and 9.0 nm were prepared from organometallic {Fe[N(SiMe3)2]2}2 and intercalated into mesoporous MCF-17 silica. We observed high turnover frequencies of the catalytic CO hydrogenation; they increased with Fe particle size. Methane and short-chain olefin selectivities were highest for small particles, while the opposite trend applied to long-chain terminal olefins and oxygenates. The Anderson–Schulz–Flory chain lengthening probabilities were found to increase with Fe particle size for both paraffins and terminal olefins. Reaction-induced sintering of the metal particles was limited and could be explained by the transformation of Fe(0) precursors into (mainly) Fe-carbides. The results cast new light on the structure sensitivity of the catalytic CO hydrogenation.

Catalytic hydrogenation of carbon monoxide over Rh–Mn–Li/SiO2 catalyst for the synthesis of C2+ oxygenates: the remarkable effect of urea on the particle size of Rh

A series of Rh-Mn-Li/SiO2 catalysts were prepared by the impregnation of a silica support with solutions containing metal precursors with different amounts of urea. Catalyst performance was investigated by the hydrogenation of carbon monoxide. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, hydrogen chemisorption, diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopy, and thermogravimetric analysis. The results revealed that the amount of urea had a significant effect on the particle size of Rh, which increased from approximately 2-5 nm with the increase in urea loading from 0 to 2.0 wt%. DR UV-Vis spectra indicated that the increase in the Rh particle size with increasing urea loading might be attributed to the coordination of Rh3+ with urea or its derivatives during calcination. At a urea loading of 1.0 wt%, the particle size of Rh was 3.7 nm, and the space time yield of C2+ oxygenates reached a maximum of 560.0 g kg(-1) h(-1).

Formaldehyde production via hydrogenation of carbon monoxide in the aqueous phase

Discovery of a low temperature route to produce formaldehyde via catalytic hydrogenation of carbon monoxide in the aqueous phase.

Time-Resolved (2 s) Study of the Initial Steps of the Catalytic Hydrogenation of CO: From Branched Isomers to Unsaturated Molecules

The catalytic hydrogenation of carbon monoxide, known as the Fischer–Tropsch process, is a technologically important, complex multipath reaction which produces long-chain hydrocarbons. In order to ...

Graphitic mesoporous carbon-supported molybdenum carbides for catalytic hydrogenation of carbon monoxide to mixed alcohols

Molybdenum carbide (β-Mo2C) nanoparticles were synthesized in situ on a soft-templated graphitic mesoporous carbon (GMC) and other commercial carbon materials (activated charcoal and carbon black) by carbothermal hydrogen reduction (i.e., carbon supports as carburizing agents). The catalytic activity of these carbon-supported and bulk carbides for carbon monoxide (CO) hydrogenation to mixed alcohols (mainly C1–C3) was investigated at 573K and 3.0MPa, showing that their areal specific rates for CO conversion increase with decreasing the carbide particle size, independent of the supports. GMC appears to be a preferable support of β-Mo2C to activated charcoal and carbon black because of its ability for the formation of smaller carbide particles resulting in higher catalytic activity. Addition of a minor amount of K2CO3 into β-Mo2C/GMC (molar K/Mo=0.05−0.5) promotes the formation of higher alcohols (C2+–OH) considerably, leading to a maximum space time yield (STY) for C2+–OH at medium K/Mo ratio of 0.1. Compared with typical Rh/GMC catalyst promoted triply with Mn, Li, and Fe oxides, the K2CO3-promoted β-Mo2C/GMC catalyst shows higher C2+–OH selectivity (30 vs. 25mol-C% on CO2-free basis) and STY (71 vs. 46mg(hgcat)−1) in spite of its suppressed formation of CH3OH.

Generation of light hydrocarbons through Fischer–Tropsch synthesis: Identification of potentially dominant catalytic pathways via the graph–theoretic method and energetic analysis

The Fischer–Tropsch synthesis (FTS) for the production of widely distributed hydrocarbons through the catalytic hydrogenation of carbon monoxide (CO) has been intensively and extensively explored. This is attributable to its immense theoretical as well as practical importance. Naturally, such exploration would be greatly facilitated if the feasible or dominant catalytic pathways (mechanisms) of FTS can be determined. The stoichiometrically feasible and independent catalytic pathways (IP i 's) of FTS have been exhaustively identified via the rigorous graph–theoretic method based on P-graphs (process graphs). The most extensive set of elementary reactions available, which numbers 26, has yielded 24 IP i 's in less than 1 s on a PC. The plausibly dominant pathways have been selected from the stoichiometrically feasible pathways through the analysis of their activation energies. Naturally, the dominant pathway or pathways need ultimately be discriminated among these plausibly dominant pathways via various means, e.g., in situ spectroscopic measurements of intermediates.

The influence of the support on the activity and selectivity of Pd in CO hydrogenation

Catalytic hydrogenation of carbon monoxide was studied over Pd supported on Al 2O 3, SiO 2, TiO 2, and ZrO 2. Both the activity and the selectivity of the catalysts were strongly affected by the nature of the support. As a major product, Pd/Al 2O 3 produces dimethyl ether, Pd/SiO 2 favors methanol formation, Pd/TiO 2 produces CH 4, and Pd/ZrO 2 yields methanol. Higher CO conversions over Pd/ZrO 2 and Pd/TiO 2 were ascribed to the presence of cationic palladium species formed through the metal–support interaction. Significant dimethyl ether formation over Pd/Al 2O 3 was attributed to the acidity of the support metal oxide. The catalytic natures of Pd catalysts were discussed based on the results of catalyst characterization by XPS, TEM, and temperature-programmed reduction and desorption.

Vibrational spectroscopic study of IB metal/zirconia catalysts for the synthesis of methanol

Catalytic hydrogenation of carbon monoxide and carbon dioxide is studied over copper/zirconia and silver promoted copper/zirconia catalysts. Vibrational spectroscopy is used to obtain information on the reaction mechanism leading to methanol by in situ identification of the adsorbed species and intermediates in the pressure range from 3 to 25 bar. The water-gas shift reaction producing CO 2 from CO and vice versa plays a crucial role in the mechanism. This reaction is shown to proceed in a basic variant via surface carbonates in the presence of surface hydroxyl groups. Surface bound formaldehyde and methylate are the pivotal intermediates on the route to methanol, whereas formate is not a direct precursor of the desired methanol product. The addition of silver as a promoter results in enhanced selectivities and productivities for methanol. The most prominent feature of the spectroscopic measurements on the silver promoted copper/zirconia catalyst is the high surface concentration of surface formaldehyde which is formed on or stabilised by the silver component.

ChemInform Abstract: Surface Species on the Oxidized K2CO3/MoS2 and Their Effects on Catalytic Carbon Monoxide Hydrogenation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Catalytic hydrogenation of carbon monoxide over silica-supported Ir-Mo-Rh catalyst

We present here some results on Ir-Mo-Rh metallic catalysts for the synthesis of C2-C4 alcohols from syngas. It was found that Ir-Mo-Rh supported on silica containing small amounts of Rh exhibited much higher activity for CO hydrogenation than Ir-Mo bimetallic catalyst. The selectivity to various alcohols did not change very much upon the addition of Rh. The activity was greatly affected by the impregnation procedure of the metals in the catalyst preparation.

Surface species on the oxidized K 2CO 3/MoS 2 and their effects on catalytic carbon monoxide hydrogenation

The properties of K 2CO 3/MoS 2 oxidized at room temperature and the effects of thermal treatments of the sample on its catalytic activity and physicochemical properties were investigated by means of temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy, infrared. X-ray dif- fraction and electron spin resonance. The TPD exhibited four peaks of SO 2 evolution. Among them, three peaks originated from the decomposition of surface SO 2− 4 species with C 2v and T d symmetries. The decomposition of sulfate by heat treatment resulted in the production of SO 2 and oxidized molybdenum species such as MoO 3+ which were converted to MoO 2 by further heat treatment. The thermal treatment of oxidized catalyst above 1013 K caused a solid-state reaction between potassium and molybdenum, producing K 2MoO 4. The treated catalyst on which the surface SO 2− 4 species had been removed, recovered their selectivity to alcohol formation in CO-H 2 reactions which had been lost when the catalysts were oxidized.

Spectroscopic investigations of catalytic iridium carbonyl species in sodium chloroaluminate melts

In situ spectroscopic studies of the iridium chemistry occurring during the catalytic hydrogenation of carbon monoxide employing IrCl(CO) 3 and Ir 4(CO) 12 in an aluminum chloride-sodium chloride (63:37 mole%) melt were performed. Infrared, UV-visible, Raman, and 1H NMR data indicate that similar monomeric species are generated during catalysis. Infrared investigation of the introduction of IrCl(CO) 3 into molten AlCl 3:NaCl (63:37) under CO:H 2 (1:3 mole ratio) and the reaction between IrCl(CO) 3 and carbon monoxide in an acidic melt suggest the initial formation of an iridium-carbonyl species followed by the generation of a hydridocarbonyl complex in the initial stage of the catalysis. Infrared data also indicate that the method of introduction for Ir 4(CO) 12 into the AlCl 3:NaCl medium under 1 atm of CO:H 2 (1:3 mole ratio) has a marked effect on the spectra observed. In an acidic melt IrCl(CO) 3 reacts with hydrogen to form hydrogen chloride, methane and metallic iridium.