Methanol Formation Research Articles

Alcohol-Assisted Hydrogenation of Carbon Monoxide to Methanol Using Molecular Manganese Catalysts.

Alcohol-assisted hydrogenation of carbon monoxide (CO) to methanol was achieved using homogeneous molecular complexes. The molecular manganese complex [Mn(CO)2Br[HN(C2H4PiPr2)2]] ([HN(C2H4PiPr2)2] = MACHO-iPr) revealed the best performance, reaching up to turnover number = 4023 and turnover frequency 857 h–1 in EtOH/toluene as solvent under optimized conditions (T = 150 °C, p(CO/H2) = 5/50 bar, t = 8–12 h). Control experiments affirmed that the reaction proceeds via formate ester as the intermediate, whereby a catalytic amount of base was found to be sufficient to mediate its formation from CO and the alcohol in situ. Selectivity for methanol formation reached >99% with no accumulation of the formate ester. The reaction was demonstrated to work with methanol as the alcohol component, resulting in a reactive system that allows catalytic “breeding” of methanol without any coreagents.

Relations between Surface Oxygen Vacancies and Activity of Methanol Formation from CO2 Hydrogenation over In2O3 Surfaces

As a promising catalyst for methanol synthesis from CO2 hydrogenation, In2O3 has attracted considerable interest due to its high methanol selectivity. Understanding the structure–activity relations...

Understanding Selectivity in CO2 Hydrogenation to Methanol for MoP Nanoparticle Catalysts Using In Situ Techniques

Molybdenum phosphide (MoP) catalyzes the hydrogenation of CO, CO2, and their mixtures to methanol, and it is investigated as a high-activity catalyst that overcomes deactivation issues (e.g., formate poisoning) faced by conventional transition metal catalysts. MoP as a new catalyst for hydrogenating CO2 to methanol is particularly appealing for the use of CO2 as chemical feedstock. Herein, we use a colloidal synthesis technique that connects the presence of MoP to the formation of methanol from CO2, regardless of the support being used. By conducting a systematic support study, we see that zirconia (ZrO2) has the striking ability to shift the selectivity towards methanol by increasing the rate of methanol conversion by two orders of magnitude compared to other supports, at a CO2 conversion of 1.4% and methanol selectivity of 55.4%. In situ X-ray Absorption Spectroscopy (XAS) and in situ X-ray Diffraction (XRD) indicate that under reaction conditions the catalyst is pure MoP in a partially crystalline phase. Results from Diffuse Reflectance Infrared Fourier Transform Spectroscopy coupled with Temperature Programmed Surface Reaction (DRIFTS-TPSR) point towards a highly reactive monodentate formate intermediate stabilized by the strong interaction of MoP and ZrO2. This study definitively shows that the presence of a MoP phase leads to methanol formation from CO2, regardless of support and that the formate intermediate on MoP governs methanol formation rate.

Stepwise methane to methanol conversion: Effect of copper loading on the formation of active species in copper-exchanged mordenite

This work investigates the influences of Cu content, Si/Al ratio, and sample preparation method on the active Cu species in mordenite (MOR). The Cu/MOR prepared by multiple Cu-exchange procedures showed an optimum Cu/Al ratio for the formation of the most active species for methanol formation. XANES spectra indicated that isolated Cu+ species were formed after CH4 interaction and were re-oxidized under a flow of water steam. The Cu-MOR samples obtained by ion-exchange method presented well-dispersed CuO in the zeolite pores, while samples obtained by impregnation method presented segregated CuO and were inactive for CH4 activation. The methodology used for in situ UV–vis spectra analyses indicated that different Cu species were active for CH4 oxidation. Isolated Cu2+ species were not involved in CH4 activation at temperatures lower than 300 °C. The isolated Cu2+ species were partially hydrolyzed by O2 treatment and species like [CuOH]+ and [CuOx]n or polynuclear Cu2+-oxyhydroxide were formed. The formation of polynuclear species in substitution of di-copper would impact the specific activity with the Cu content and decrease the activity for methanol production.

A DFT-based microkinetic study on methanol synthesis from CO2 hydrogenation over the In2O3 catalyst.

In this work, we performed density functional theory (DFT)-based microkinetic simulations to elucidate the reaction mechanism of methanol synthesis on two of the most stable facets of the cubic In2O3 (c-In2O3) catalyst, namely the (111) and (110) surfaces. Our DFT calculations show that for both surfaces, it is difficult for the H atom adsorbed at the remaining surface O atom around the O vacancy (Ov) active site to migrate to an O adsorbed at the Ov due to the very high energy barrier involved. In addition, we also find that the C-O bond in the bt-CO2* chemisorption structure can directly break to form CO with a lower energy barrier than that in its hydrogenation to the COOH* intermediate in the COOH route. However, our microkinetic simulations suggest that for both surfaces, CO2 deoxygenation to form CO in both pathways, namely the COOH and CO-O routes, are kinetically slower than methanol formation under typical steady state conditions assuming a CO2 conversion of 10% and a CO selectivity of 1%. Although these results agree with previous experimental observations at relatively low reaction temperature, where methanol formation dominates, they cannot explain the predominant formation of CO at relatively high reaction temperature. We tentatively attribute this to the simplicity of our microkinetic model as well as possible structural changes of the catalyst at relatively high reaction temperature. Furthermore, although the rate-determining step (RDS) from the degree of rate control (DRC) analysis is usually consistent with that judged from the DFT calculated energy barriers, for CO2 hydrogenation to methanol over the (111) surface, our DRC analysis suggests homolytic H2 dissociation to be the rate-controlling step, which is not apparent from the DFT-calculated energy barriers. This indicates that CO2 conversion and methanol selectivity over the (111) surface can be further enhanced if homolytic H2 dissociation can be accelerated for instance by introducing transition metal dopants as already shown by some experimental observations.

A potential catalyst for continuous methane partial oxidation to methanol using N2O: Cu-SSZ-39.

Continuous catalytic methanol production from methane is reported on Cu-SSZ-39 using N2O as an oxidant. Through optimization of CH4, N2O and H2O partial pressures, a methanol formation rate of 499 μmolCH3OH g-1 h-1 and a methanol selectivity of 34% is achieved.

ENERGÍAS Y MODOS VIBRACIONALES DE ESPECIES FORMADAS POR DESHIDROGENACIÓN DE CH4 EN PRESENCIA DE O2 SOBRE Cr2O3(0001)

In this work we perform a theoretical study of dehydrogenation process of CH4 on O2– in both molecular and dissociative states - previously adsorbed on Cr2O3(0001). Calculations are based on Density Functional Theory (DFT). The results show the methanol formation form the adsorption of CH4 on O2 in dissociative state with a formationenergy5:14 eV. Also formaldehyde was formed by the reaction of CH2with molecular O2(Eads=6:09 eV) and dioxymethylene by the reaction of CH2with O2 previously adsorbed in dissociative state on Cr2O3(0001), withEads=8:17 eV. Finally, the vibrational modes found by DFT for each of the species were compared, which are in good agreement with those of reference bibliography. This allows us to support the values found both by technical calculations and by experimental methods.

Selective methanol formationviaCO-assisted direct partial oxidation of methane over copper-containing CHA-type zeolites prepared by one-pot synthesis

Catalytic CO-assisted partial oxidation of methane to methanol was demonstrated over Cu-CHA zeolites that were prepared by a one-pot synthesis approach feasible to prepare isolated metal sites.

A Theoretical Study of the Hydrogenation of CO over Co2Cu2 Bimetallic Catalyst Supported on MgO(200) by Means of Density Functional Theory Part 2: Reaction Mechanism

This paper investigates the hydrogenation of carbon monoxide (CO) over Co2Cu2 bimetallic catalyst supported on MgO (200) using a combination of density functional theory (DFT) and a climbing image nudged elastic band (CI-NEB) module. In the study, a reaction mechanism for the formation of methane, methanol and ethanol was proposed. The proposed mechanism consisted of 28 reaction steps (per surface type) and three different reaction positions were included. Reaction energy and activation energy for the overall steps involved in the reaction process were calculated and analyzed. The results show that the CoCu mixed sites reduced the activation energy of the CO insertion process into CH3, resulting in the formation of products with a larger number of carbon atoms.

Numerical study on the reaction mechanism of CO2 hydrogenation in atmospheric-pressure dielectric barrier discharge

Recently, the catalytic conversion of greenhouse gases by plasma technology has attracted more and more attention. In this paper, a two-dimensional fluid model is developed to study the reaction mechanism of plasma CO2 hydrogenation in atmospheric-pressure dielectric barrier discharge (DBD). The effect of varying volume ratio of CO2/H2 on reaction mechanism of CO2 hydrogenation is studied carefully, such as temporal and spatial density distributions of main radicals and ions, dynamics of streamer propagation, and generation and loss pathways of H, CO, and CH3OH. It is found that H, O, and CO are the three most abundant species, and lower hydrogen content in gas mixture promotes streamer propagation and the formation of conduction current in plasma column. Besides, H is mainly produced by electron-impact dissociation of H2 (e + H2 ⇒ e + 2H); O and CO are dominantly produced by electron-impact dissociation of CO2 (e + CO2 ⇒ e + CO + O). Interestingly, H addition reaction to the intermediate species CH3O (CH3O + H ⇒ CH3OH) is found to be the main reaction pathway for methanol formation. Finally, a schematic overview of dominant reaction pathways for plasma CO2 hydrogenation in atmospheric DBD is presented, which ultimately leads to a better understanding of the intrinsic reaction mechanism.

Investigation on Formation Mechanisms of Methanol During Cellulose Insulation Aging Based on Molecular Dynamics Simulation

In recent years, methanol has been proposed as a chemical indicator to assess the aging condition of cellulose insulation in oil-immersed power transformers. However, the formation mechanisms of methanol during cellulose degradation are not clear enough. In this paper, such formation mechanisms were studied using molecular dynamics simulation. Three main formation pathways of methanol were found and discussed. Analysis of the Mayer bonds of cellulose revealed that each atom of cellulose contributes differently to methanol formation. The methylol groups on the 5-carbon atom of the 1-pyran ring and 4-pyran ring of cellulose are more readily detached to form methanol molecules. In addition, changes in the amount of methanol molecule with simulation time were investigated. The results indicated that the separate existence of initial moisture and oxygen has no significant effect on the formation of methanol, while the co-existence of initial moisture and initial oxygen catalyzes the conversion of cellulose degradation products to methanol. The findings reported in this paper can provide a valuable theoretical basis for further studies on methanol as an indicator to evaluate the residual life of cellulose insulation.

Alcohol Production from Carbon Dioxide: Methanol as a Fuel and Chemical Feedstock

Summary Production of renewable alcohols from air, water, and sunlight present an avenue to utilize captured carbon dioxide for the production of basic chemicals and store renewable energy in the chemical bonds of liquid fuels. Of the technologies that utilize CO2 directly, CO2 electrolysis, as well as CO2 hydrogenation coupled with H2O electrolysis, have the benefit of requiring only CO2, H2O, and renewable electricity as inputs with O2 as a sole byproduct. Among alcohols, renewable methanol has seen the most development and analysis in the chemical industry because it is currently a syngas-derived product that could be adapted for direct CO2 utilization. In this perspective, we compare renewably powered CO2 electrolysis and CO2 hydrogenation with the incumbent methanol production method from syngas from a cost and CO2 life cycle perspective by analyzing recent literature to identify the research goals that enable further scale-up. Survey of the industry shows that CO2 hydrogenation is among the closest CO2 utilization technologies to large-scale deployment. We further discuss these CO2 hydrogenation systems and the catalysts that drive them, with recommendations to drive further development and scale-up.

Reinvestigation of the rotation-tunneling spectrum of the CH2OH radical

Context. The hydroxymethyl radical (CH2OH) is one of two structural isomers, together with the methoxy radical (CH3O), that can be produced by abstraction of a hydrogen atom from methanol (CH3OH). In the interstellar medium (ISM), both CH2OH and CH3O are suspected to be intermediate species in many chemical reactions, including those of formation and destruction of methanol. The determination of the CH3O/CH2OH ratio in the ISM would bring important information concerning the formation processes of these species in the gas and solid phases. Interestingly, only CH3O has been detected in the ISM so far, despite the recent first laboratory measurement of the CH2OH rotation-tunneling spectrum. This lack of detection is possibly due to the non-observation in the laboratory of the most intense rotation-tunneling transitions at low temperatures. Aims. To support further searches for the hydroxymethyl radical in space, we present a thorough spectroscopic study of its rotation-tunneling spectrum, with a particular focus on transitions involving the lowest quantum numbers of the species. Methods. We recorded the rotation-tunneling spectrum of CH2OH at room temperature in the millimeter-wave domain using a frequency multiplication chain spectrometer. A fluorine-induced H-abstraction method from methanol was used to produce the radical. Results. About 180 transitions were observed, including those involving the lowest N and Ka quantum numbers, which are predicted to be intense under cold astrophysical conditions. These transitions were fitted together with available millimeter-wave lines from the literature. A systematic observation of all components of the rotational transitions yields a large improvement of the spectroscopic parameters allowing confident searches of the hydroxymethyl radical in cold to warm environments of the ISM.

Methanol formation chemistry with revised reactions scheme

The aim of the presented work is to analyze the impact of experimentally evaluated reactions of hydrogen abstraction on surfaces of interstellar grains on the chemical evolution of methanol and its precursors on grains and in the gas phase under conditions of a cold dark cloud and during the collapse of a translucent cloud into a dark cloud. Analysis of simulation results shows that those reactions are highly efficient destruction channels for HCO and H2CO on grain surfaces, and significantly impact the abundances of almost all molecules participating in the formation of CH3OH. Next, in models with those reactions, maximum abundances of methanol in gas and on grain surfaces decrease by more than 2–3 orders of magnitude in comparison to models without surface abstraction reactions of hydrogen. Finally, we study the impact of binding energies of CH2OH and CH3O radicals on methanol chemistry.

A survey of CH2DOH towards starless and pre-stellar cores in the Taurus molecular cloud

ABSTRACT Recent observations indicate that organic molecules are prevalent towards starless and pre-stellar cores. Deuteration of these molecules has not been well studied during the starless phase. Published observations of singly deuterated methanol, CH2DOH, have only been observed in a couple of well-studied, dense, and evolved pre-stellar cores (e.g. L1544, L183). Since the formation of gas-phase methanol during this cold phase is believed to occur via desorption from the icy grain surfaces, observations of CH2DOH may be useful as a probe of the deuterium fraction in the ice mantles of dust grains. We present a systematic survey of CH2DOH towards 12 starless and pre-stellar cores in the B10 region of the Taurus molecular cloud. Nine of the 12 cores are detected with [CH2DOH]/[CH3OH] ranging from <0.04 to 0.23$^{+0.12}_{-0.06}$ with a median value of 0.11. Sources not detected tend to have larger virial parameters and larger methanol linewidths than detected sources. The results of this survey indicate that deuterium fractionation of organic molecules, such as methanol, during the starless phase may be more easily detectable than previously thought.

Reaction-driven surface reconstruction of ZnAl2O4 boosts the methanol selectivity in CO2 catalytic hydrogenation

Identifying the surface structure of heterogeneous catalysts is critical for understanding the active sites, but it remains challenging due to the difficulty in characterizing the catalytic surfaces especially at elevated temperatures. Zn-based catalysts are high-efficiency alternatives for high-temperature methanol synthesis from CO2, as well as in bifunctional catalysts for hydrocarbons synthesis. Herein, the surface reconstruction of ZnAl2O4 spinel during CO2 hydrogenation reaction was investigated using detailed spectroscopic characterization. The results indicate that the reaction-driven surface reconstruction leads to the formation of amorphous ZnO on the ZnAl2O4 surface, which is accompanied by the increasing catalytic activity for methanol production. Kinetic analysis, STEM and in situ FTIR results indicate that the amorphous ZnO boosts the methanol formation rate by promoting the activation of H2. This study provides useful insight into the structure-activity relationship of zinc-based catalysts for CO2 hydrogenation and future design of new catalysts.

Low‐Temperature, Ambient Pressure Oxidation of Methane to Methanol Over Every Tri‐Iron Node in a Metal–Organic Framework Material

In contrast with metal-modified zeolites, metal-organic framework materials (MOFs) provide a platform that may be significantly more amenable to creating catalysts in which every metal site is endowed with the same coordination environment, and hence, catalytic function. Using MIL-100(Fe) as a prototype, we present the first example of a synthetic heterogeneous catalyst comprised exclusively of active tri-iron moieties participating in the low-temperature oxidation of methane to methanol; in contrast with prior reports on iron-MOFs, we report the near-exclusive formation of methanol at low temperatures and sub-ambient methane pressures, and evidence its effectuation solely by Fe2+ sites. The study captures the utility of exploring classes of materials endowed with a high level of definition in structure and catalytic function for the purposes of overcoming persistent scientific and technological challenges in the field of synthetic heterogeneous catalysis.

Inverse ZrO2/Cu as a highly efficient methanol synthesis catalyst from CO2 hydrogenation

Enhancing the intrinsic activity and space time yield of Cu based heterogeneous methanol synthesis catalysts through CO2 hydrogenation is one of the major topics in CO2 conversion into value-added liquid fuels and chemicals. Here we report inverse ZrO2/Cu catalysts with a tunable Zr/Cu ratio have been prepared via an oxalate co-precipitation method, showing excellent performance for CO2 hydrogenation to methanol. Under optimal condition, the catalyst composed by 10% of ZrO2 supported over 90% of Cu exhibits the highest mass-specific methanol formation rate of 524 gMeOHkgcat−1h−1 at 220 °C, 3.3 times higher than the activity of traditional Cu/ZrO2 catalysts (159 gMeOHkgcat−1h−1). In situ XRD-PDF, XAFS and AP-XPS structural studies reveal that the inverse ZrO2/Cu catalysts are composed of islands of partially reduced 1–2 nm amorphous ZrO2 supported over metallic Cu particles. The ZrO2 islands are highly active for the CO2 activation. Meanwhile, an intermediate of formate adsorbed on the Cu at 1350 cm−1 is discovered by the in situ DRIFTS. This formate intermediate exhibits fast hydrogenation conversion to methoxy. The activation of CO2 and hydrogenation of all the surface oxygenate intermediates are significantly accelerated over the inverse ZrO2/Cu configuration, accounting for the excellent methanol formation activity observed.

CO2 Reduction to Methanol in the Liquid Phase: A Review.

Excessive carbon dioxide (CO2 ) emissions have been subject to extensive attention globally, since an enhanced greenhouse effect (global warming) owing to a high CO2 concentration in the atmosphere could lead to severe climate change. The use of solar energy and other renewable energy to produce low-cost hydrogen, which is used to reduce CO2 to produce bulk chemicals such as methanol, is a sustainable strategy for reducing carbon dioxide emissions and carbon resources. CO2 conversion into methanol is exothermic, so that low temperature and high pressure are favorable for methanol formation. CO2 is usually captured and recovered in the liquid phase. Herein, the emerging technologies for the hydrogenation of CO2 to methanol in the condensed phase are reviewed. The development of homogeneous and heterogeneous catalysts for this important hydrogenation reaction is summarized. Finally, mechanistic insight on CO2 's conversion into methanol over different catalysts is discussed by taking the available reaction pathways into account.

CO hydrogenation over K‐Co‐MoSx catalyst to mixed alcohols: A kinetic analysis

AbstractHigher alcohol synthesis (HAS) from syngas is one of the most promising approaches to produce fuels and chemicals. Our recent investigation on HAS showed that potassium‐promoted cobalt‐molybdenum sulfide is an effective catalyst system. In this study, the intrinsic kinetics of the reaction were studied using this catalyst system under realistic conditions. The study revealed the major oxygenated products are linear alcohols up to butanol and methane is the main hydrocarbon. The higher alcohol products (C3+) followed an Anderson‐Schultz‐Flory distribution while the catalyst suppressed methanol and ethanol formation. The optimum reaction conditions were estimated to be at temperature of 340°C, pressure of 117 bar, gas hourly space velocity of 27 000 mL g–1 h–1 and H2/CO molar feed ratio of 1. A kinetic network has been considered and kinetic parameters were estimated by nonlinear regression of the experimental data. The results indicated an increasing apparent activation energy of alcohols with the length of alcohols except for ethanol. The lower apparent activation energy of alcohols compared with hydrocarbon evidenced the efficiency of this catalyst system to facilitate the formation of higher alcohols.