Conversion Of MeOH Research Articles

(Invited) Scaling CO2 to MeOH Conversion in an Electrolyzer

Methanol is a desirable, value-added product from CO2 electroreduction, but is difficult to obtain in high Faradaic efficiencies. Promising results have emerged from a catalyst system comprised of cobalt pthalocyanine adsorbed onto carbon nanotubes (CoPc/CNT) in batch cell reactors, reaching Faradaic efficiencies of 40-50%.(1) In this talk, we will present our work on scaling this reaction in a 25 cm2 flow reactor with a gas diffusion electrode. We discuss the differences in the two geometries (electrolyzer vs. batch reactor) and the effect of different process conditions, such as pH, electrolyte identity and CO2 partial pressure on product selectivities. Y. Wu, Z. Jiang, X. Lu, Y. Liang, H. Wang, Nature. 575, 639–642 (2019).

Molecular Solvation Environment Controls the Active Site in Cation-Mediated Electrocatalytic CO2 Reduction to Methanol

Electrocatalytic synthesis of higher-value products from waste molecules is an emerging technique for sustainable chemical catalysis. Heterogeneous molecular electrocatalysts are an important group of materials where the catalytic activity and selectivity can be controlled using molecularly defined active sites. Despite extensive efforts to synthesize better molecular catalysts, the effects of molecular aggregation, which dominates the interaction of the catalyst with the electrode surface as well as with the electrochemical solvation environment, are not fully understood. Using cobalt phthalocyanine (CoPc) dispersed on carbon nanotubes (CNTs) as a model system, we find that controlling the direct interaction of the molecular catalyst with cations in the electrochemical double layer (EDL) results in significantly enhanced performance for CO2 reduction (CO2RR). Specifically, molecular dispersion of the CoPc onto CNTs yields a 4-fold increase in total current density and 8-fold increase in methanol (MeOH) selectivity compared to aggregated CoPc physically mixed with the same CNT support, enabling CO2 to MeOH conversion with 42.34% Faradaic efficiency (FE). Using surface-selective sum-frequency generation (SFG) vibrational spectroscopy, direct detection of reaction intermediates reveals that the potential-dependent adsorption of two distinct CO intermediates at two types of active sites, one less active and producing mostly CO, the other more active and able to produce methanol. DFT calculations show that the CO intermediate responsible for selective MeOH production results from the direct interaction with cations present in the EDL. This interaction, which is only possible when CoPc is molecularly dispersed on the electrode surface, is responsible for the cation-assisted conversion of CO to MeOH. Control experiments using either strongly hydrated Li+, or chelated K+ by 18-crown-6-ether, which suppress MeOH formation, further confirms the important role of this interaction. Similarly significant enhancement effects are also observed for nitrate reduction reaction (NO3RR) and oxygen reduction reaction (ORR), showing that dispersing molecular catalysts into monomers states is a general design parameter required to enhance activity and selectivity by cation-assisted reaction kinetics inside the EDL.

High-silica KFI zeolite: highly efficient synthesis and catalysis in methanol amination reaction

The hydrogen form of low-silica KFI zeolite, with a Si/Al ratio of 3.2 (referred to as H-KFI-3.2), has been shown to possess significant selectivity for monomethylamine (MMA) and dimethylamine (DMA) in methanol amination reactions. However, its industrial viability for MMA and DMA synthesis has been hindered by its relatively low methanol (MeOH) conversion and yield of MMA plus DMA. In this study, we synthesize high-silica KFI zeolite with an elevated framework Si/Al ratio of 5.4 (designated as KFI-5.4) using a novel K+ and 18-crown-6 complex [referred to as (K+)CCH, with a ratio of 18-crown-6 to K+ of 2.85] as an organic structure-directing agent. Control experiments have demonstrated that the presence of both K+ and OH- ions is essential for the formation of KFI-5.4 zeolite. The hydrogen form of KFI-5.4 (H-KFI-5.4) exhibits significantly enhanced MeOH conversion (95.2%) and yield (75.1%) of MMA plus DMA compared to the low-silica H-KFI-3.2 under similar reaction conditions. This represents the highest level of catalytic performance among reported small-pore zeolites to date. Furthermore, the yield and selectivity of MMA plus DMA can be further improved by modifying KFI-5.4 with an appropriate loading of Na+, which suppresses the formation of the by-product dimethyl ether. This study introduces a new high-silica KFI zeolite catalyst with exceptional MeOH conversion and yield for the production of MMA plus DMA.

Direct synthesis of C2-C4 alcohols with methanol and CaC2 by tandem reactions

Methanol (MeOH) and calcium carbide (CaC2) are important platform compounds and many downstream chemicals have been produced from them. However, direct conversion of MeOH to higher alcohols remains a challenging topic due to the absence of β-H in MeOH. In this study, direct synthesis of ethanol (EtOH), n-propanol and isobutanol without the use of metal catalysts and H2 was achieved in one pot at temperatures above 350 °C. After a 6-hour period at 425 °C, the total yield of these alcohols reaches 54.6%. The reaction route was mainly explored via 13C-labeling experiments and an exhaustive analysis on the gas and solid products. The results indicate that the rapid reaction of MeOH with the alkynyl moiety of CaC2 leads to the formation of methyl vinyl ether (MVE). MVE undergoes gradual hydrocracking, resulting in the formation of EtOH and methane, where MeOH severs as the provider of active hydrogen. In subsequent stages, EtOH progressively reacts with MeOH, yielding n-propanol and isobutanol. It is speculated that calcium methoxide (Ca(OCH3)2), a solid product of the CaC2 and MeOH reaction, may potentially exert a catalytic influence by facilitating the dehydrogenation of MeOH and the condensation of EtOH.

Life cycle assessment of methanol production and conversion into various chemical intermediates and products

Transportation sector, particularly road transport, together with the industrial expansion stand out as key factors behind the unprecedented CO2 levels, hence the need for green fuel alternatives and sustainable technologies. The present investigation evaluates methanol (MeOH) production via direct CO2 hydrogenation, and conversion into valuable derivatives: i) formalin, ii) dimethyl ether (DME), iii) methyl tert-butyl ether (MTBE), and iv) biodiesel through modelling and simulation, as well as environmental assessment. Hydrogen is produced by water electrolysis considering three different energy scenarios: i) EU grid mix; ii) wind power; iii) hydro power. The amount of CO2 needed is obtained from cement manufacturing through a chemical scrubbing process using Methyl-Di-Ethanol-Amine (MDEA). The environmental analysis is carried out following the Life Cycle Assessment (LCA) methodology using GaBi software, and ReCiPe as impact assessment method. The key performance indexes, main product purity (>99%) and energy requirements (i.e., 1.72 MWe/t, and 5.89 MWe/t respectively) point towards alkali biodiesel, and MTBE production as the most promising MeOH conversion routes. The environmental analysis highlights that MeOH production and conversion towards alkali biodiesel process displays the lowest impact score for each energy scenario. The second-best conversion route is MTBE when using the grid mix energy scenario, and formalin when wind or hydro power is considered.

Amination of methanol for selective production of acetonitrile over Zn-Al mixed oxide catalysts synthesized at different pH

Zn–Al mixed oxides with different acidic and basic natures were synthesized under different pH (8.0–9.5) conditions and applied to the amination of methanol (MeOH). The physical and chemical properties of the samples were characterized using X-ray diffraction (XRD), N2 sorption, and X-ray photoelectron spectroscopy (XPS), as well as temperature-programmed desorption (TPD) with different probe molecules, such as NH3, CO2, iso-propanol (IPA), and MeOH. The conversion of MeOH and selectivity to acetonitrile (ACN) increased as the pH of the synthetic mixture increased to 9.5. The activity of the catalysts was in good accordance with the desorption temperatures of propylene in IPA-TPD and dimethyl ether in MeOH-TPD, while their selectivity to ACN was well correlated with the proportion of the weak base sites on the surface of the catalyst. Particularly, the changes in the acidity and basicity of the catalysts with the synthesis pH were mainly influenced by the degree of disorder of the ZnAl2O4 spinel structure. During the amination of MeOH, the catalytic activity, product selectivity, and deactivation behavior of the catalysts were affected by the reaction parameters. The Zn–Al mixed oxide catalyst was readily regenerated by via simple calcination, which removed the carbonitride and coke that were formed during the reaction.

An integrated approach to the key parameters in methanol-to-olefins reaction catalyzed by MFI/MEL zeolite materials

Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin (MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large MeOH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by 27Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.

Comparative feasibility studies of H2 supply scenarios for methanol as a carbon-neutral H2 carrier at various scales and distances

Hydrogen (H2) energy has come to the fore as a significant role of chemical industry in achieving a sustainable energy sector under serious environmental problems. Therefore, research for using H2 as an energy carrier has been actively conducted. However, H2 has very low volumetric energy density making it require conversion to other forms to acquire higher volumetric energy density. In this paper, the promising compound methanol (MeOH) was considered as a H2 carrier owing to carbon-neutral in environmental terms. The two main overall H2 supply scenarios were considered. The first case covers the use of MeOH produced from various types of H2 (from steam methane reforming (SMR), coal gasification (CG), and water electrolysis (WE)), indirectly, and CO2 electrolysis, directly, as a H2 carrier, further converted to H2 at desired locations. The second case covers the conversion of MeOH from four production pathways into H2 followed by the transportation of the produced H2 via various H2 transportation methods such as compressed H2 (CH2), liquefied H2 (LH2), liquid organic hydrogen carrier (LOHC), and ammonia (NH3). In this work, diverse H2 supply scenarios considering various MeOH production methods, capacities, pathways, and distances were analyzed with unit H2 supply cost via economic analysis.

Underwater vehicle hydrogen production from methanol steam reforming using hydrogen peroxide

Methanol steam reforming (MSR) can supply hydrogen (H2) to underwater vehicles equipped with a fuel cell. Low reaction temperatures ensure the composition of the reformed gas suitable for the H2 purification unit and increase the design freedom of a reforming plant. However, such temperatures decrease the catalyst activity and thereby the methanol (MeOH) conversion and H2 production. Herein, hydrogen peroxide (H2O2) was supplied with MeOH and water (H2O) to ensure sufficient MeOH conversion and H2 production at low temperatures. A tube reactor loaded with a commercial Cu/Zn catalyst was installed in an electric furnace maintained at 200–250 °C, and MeOH and 0 wt%, 11.88 wt%, 22.51 wt%, and 32.07 wt% H2O2 were supplied. When the furnace temperature was 200 °C, the MeOH conversion was 49.3% at 0 wt% H2O2 but 93.5% at 32.07 wt% H2O2. The effect of adding H2O2 was greater under the temperature conditions where the MeOH conversion was 100% or less. To analyze the effect of H2O2 addition on catalyst durability, the furnace was maintained at 200 °C, and the reactor was continuously operated for 110 h with 0 wt% and 32.07 wt% H2O2. The addition of H2O2 did not significantly decrease the Cu/Zn catalyst durability.

Enhancing the Dispersion of Cu-Ni Metals on the Graphene Aerogel Support for Use as a Catalyst in the Direct Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol.

Graphene has attracted attention because of its interesting properties in catalyst applications including as a catalyst support; however, it is known that the graphene can be restacked, forming a graphite-like structure that leads to poor specific surface area. Hence, the high-porosity graphene aerogel was used as a Cu–Ni catalyst support to produce dimethyl carbonate (DMC) from carbon dioxide and methanol. In this work, we have introduced a new synthesis route, which can improve the dispersion of metal particles on the graphene aerogel support. Cu–Ni/graphene aerogel catalysts were synthesized by a two-step procedure: forming Cu–Ni/graphene aerogel catalysts via hydrothermal reduction and then Cu–Ni loading by incipient wetness impregnation. It is found that the catalyst prepared by the two-step procedure exhibits higher DMC yield (25%) and MeOH conversion (18.5%) than those of Cu–Ni loading only by an incipient wetness impregnation method. The results prove that this new synthesis route can improve the performance of Cu–Ni/graphene aerogel catalysts for DMC production.

Critical role of formaldehyde during methanol conversion to hydrocarbons

Formaldehyde is an important intermediate product in the catalytic conversion of methanol to olefins (MTO). Here we show that formaldehyde is present during MTO with an average concentration of ~0.2 C% across the ZSM-5 catalyst bed up to a MeOH conversion of 70%. It condenses with acetic acid or methyl acetate, the carbonylation product of MeOH and DME, into unsaturated carboxylate or carboxylic acid, which decarboxylates into the first olefin. By tracing its reaction pathways of 13C-labeled formaldehyde, it is shown that formaldehyde reacts with alkenes via Prins reaction into dienes and finally to aromatics. Because its rate is one order of magnitude higher than that of hydrogen transfer between alkenes on ZSM-5, the Prins reaction is concluded to be the major reaction route from formaldehyde to produce dienes and aromatics. In consequence, formaldehyde increases the yield of ethene by enhancing the contribution of aromatic cycle.

Conversion of MeOH and Toluene into Styrene and Ethylbenzene Using Composite Catalysts Containing MeOH Dehydrogenation Components

AbstractA new strategy, the coupling of methanol dehydrogenation and side‐chain alkylation of toluene, to realize highly effective conversion of methanol and toluene into styrene and ethylbenzene was proposed. A series of composite catalysts were designed by combining CsX with numerous catalysts reported to be effective for methanol dehydrogenation to formaldehyde. The studies of side‐chain alkylation of toluene with methanol over these composite catalysts indicated that the introduction of methanol dehydrogenation components could universally improve the yield of styrene and ethylbenzene in side‐chain alkylation of toluene with methanol. And the introduction of some methanol dehydrogenation components, i. e. sodium borate (Na2B4O7) and CuO/SiO2, could even double the yield of styrene and ethylbenzene. Furthermore, the influence of the mass ratio of different components and the spatial arrangement of different active sites on composite catalysts was investigated in detail.

Influence of dehydrating agents on the oxidative carbonylation of methanol for dimethyl carbonate synthesis over a Cu/Y-zeolite catalyst

Abstract The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate (DMC) via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl 2 ·2H 2 O and the commercial NH 4 -form of the Y type zeolite. The catalyst was characterized by X-ray fluorescence (XRF), N 2 adsorption (BET method), X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH 3 -TPD) to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave (batch reactor) for 18 h at 403 K and 5.5 MPa (2CH 3 OH + 1/2O 2 + CO ⇌ (CH 3 O) 2 CO + H 2 O). The influence of various dehydrating agents (ZnO, MgO, and CaO) was examined with the aim of increasing the methanol conversion ( X MeOH , MeOH conversion). The MeOH conversion increased upon addition of metal oxides in the order CaO >> MgO > ZnO, with the DMC selectivity ( S DMC ) following the order MgO > CaO > ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric (TG/DTG), and XRD to confirm that the dehydration reaction occurred via the metal oxide (MO + H 2 O → M(OH) 2 ). The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating agent CaO.

Hydrogen production via aqueous-phase reforming of methanol over nickel modified Ce, Zr and La oxide supports

Aqueous-phase reforming (APR) of methanol over nickel supported on zirconium, cerium and lanthanum oxides was performed in continuous laboratory scale reactor and discussed in this paper. The role of composition and physico-chemical properties of the supports were investigated and significant benefit of using mixed oxides CeO2-ZrO2 and La2O3-ZrO2 over the pure oxides, in term of methanol conversion and hydrogen production, was demonstrated. Methanol conversion of over 50% with hydrogen production efficiency of over 40% were achieved with the most active catalyst Ni/25%CeO2-ZrO2.Furthermore, catalyst stability, the most challenging issue within APR studies, was thoroughly investigated and discussed. Slight deactivation of the prepared catalysts during APR experiments or reduction was observed and addressed to the Ni particles sintering. On the other hand, other common reasons causing catalysts deactivation under APR conditions, such as leaching of Ni, changes in Ni oxidation state or changes in the supports lattice were not observed by wide range of characterization methods The most stable catalyst, Ni/10%La2O3-ZrO2, exhibited a slight decrease of MeOH conversion within two subsequent experiments (each per 6h) from 46.3% to 42.7%.

Aromatic Hydrocarbon Generation from a Simulated Bio-oil Fraction by Dual-stage Hydrogenation-cracking: Hydrogen Supply and Transfer Behaviors

The improvement of the hydrogen-poor composition of bio-oil is important for its cracking to produce aromatic hydrocarbons. In this work, a mild hydrogenation pre-treatment and methanol cocracking were combined to implement proper hydrogen supplementation for cracking. Acetic acid (HAc), hydroxypropanone (HPO), and cyclopentanone (CPO) were selected as model compounds and mixed to prepare a simulated distilled fraction (SDF) of bio-oil. The hydrogen supply and transfer behaviours in hydrogenation-cracking were investigated. For the conversion of individual components: HAc was difficult to be hydrogenated, and therefore in the cracking stage, the conversion and oil phase yield were low; ketones were successfully hydrogenated to alcohols, and thus high aromatic hydrocarbon yields were achieved. Hydrogenation-cracking of SDF showed that the inferior performance of HAc was improved by an internal hydrogen transfer, namely the alcohols produced from ketones supplied hydrogen for HAc conversion. However, because of the high HAc content in SDF, this hydrogen supplement was not sufficient. Therefore, methanol (MeOH) was used as the coreactant for secondary hydrogen supply. The integral efficient conversion of SDF and MeOH to aromatic hydrocarbons was achieved when the MeOH blending ratio was 30%. Finally, a reaction mechanism of hydrogenation-cocracking was proposed.

Synergetic Behavior of TiO2‐Supported Pd(z)Pt(1−z) Catalysts in the Green Synthesis of Methyl Formate

AbstractMethyl formate (MF) is a valuable platform molecule, the industrial production of which is far from being green. In this contribution, TiO2‐supported Pd(z)Pt(1−z) catalysts were found to be effective in the green synthesis of methyl formate (MF)—at T=323 K and ambient pressure—through methanol (MeOH) oxidation. Two series of catalysts with similar bulk Pd/(Pd+Pt) molar ratios, z, were prepared; one by a water‐in‐oil microemulsion (MicE) method and the other by an incipient wetness impregnation (IWI). The MicE method led to more efficient catalysts owing to a weak influence of z on particle size distributions and nanoparticles composition. Pd(z)Pt(1−z)‐MicE catalysts exhibited strong synergistic effects for MF production but weak synergistic effects for MeOH conversion. The catalytic performance of Pd(z)Pt(1−z)‐MicE was superior to that of Pd(z)Pt(1−z)‐IWI catalysts despite the latter displaying synergetic effects during the reaction. The catalytic behavior of TiO2‐supported Pd(z)Pt(1−z) catalysts was explained from correlations between XRD, TEM, and X‐ray photoelectron spectroscopy characterizations.

In situ spectroscopic investigations of MoOx/Fe2O3 catalysts for the selective oxidation of methanol

Methoxy adsorbed on MoOx/Fe2O3 surfaces.

Synthesis of gasoline fractions from CO and H2 through oxygenates

The technology for the manufacturing of gasoline fractions (synthetic hydrocarbons) from synthesis gas (syngas) on zeolites through the oxygenate production step as developed at the Topchiev Institute of Petrochemical Synthesis, differs from the classical MTG process of ExxonMobil in that the oxygenate and gasoline production steps are integrated in one circuit. In the new technology, the synthetic hydrocarbons contain 6 to 27 wt % aromatic hydrocarbons (benzene and durene ≤2 wt %) depending on the H2/CO ratio in syngas. When syngas with H2/CO ≤ 3.5 in the vapor-gas mixture arriving at the gasoline production stage is used, an increased methanol (MeOH) content is observed and the MeOH conversion is incomplete with the exhaustive conversion of dimethyl ether (DME). To increase the involvement of MeOH in the synthesis of the gasoline fraction, the influence of various parameters on the conversion of MeOH and DME has been studied. It has been shown that a change in the composition of fresh syngas has a more significant effect notably on the MeOH, rather than the DME conversion into synthetic hydrocarbons and is enhanced with an increase in the MeOH weight hourly space velocity (WHSV). If the vapor-gas mixture arriving from the oxygenate production reactor at the step of production of the gasoline fraction contains more than 50 wt % MeOH, in order to improve the selectivity for the gasoline fraction, the synthesis should be conducted at a lower WHSV of oxygenates than in the case when the vapor-gas mixture contains DME alone.

Steam reforming of methanol over structured catalysts prepared by electroless deposition of Cu and Zn on anodically oxidized alumina

Steam reforming of methanol (SRM) was investigated over a series of porous structured Cu–Zn/γ-Al2O3/Al catalysts. The porous γ-Al2O3 layer was synthesized on the Al substrate through anodic oxidation in an oxalic acid solution. Cu and Zn in different molar concentrations were loaded using electroless deposition over the prepared γ-alumina support. The synthesized catalysts were characterized using the BET, XRD, SEM, and energy dispersive X-ray analysis. The Cu metal surface area was measured by the selective chemisorption of nitrous oxide. The obtained γ-Al2O3/Al (AAO) had a specific surface area of 27 m2/g, and it was observed that the Al2O3 layer contained well-developed nanopores (∼60 nm), making it ideal for use as a catalyst support. The results showed that the BET surface area of the catalyst linearly decreased with the Cu–Zn loading. The Cu metal surface area increased with increasing copper concentration in the deposition bath solution. A fixed tubular reactor was designed and fabricated to evaluate the catalytic activity of the Cu–Zn/AAO catalysts for SRM. Among the catalysts, Cu(0.06)Zn(0.06)/AAO showed 78% MeOH conversion at 350 °C. MeOH conversion linearly increased with increasing electroless deposition time from 0.5 to 10 min and appeared to plateau thereafter, indicating that 10 min was the optimal loading time.

A ligand-free, powerful, and practical method for methoxylation of unactivated aryl bromides by use of the CuCl/HCOOMe/MeONa/MeOH system

A ligand-free, powerful, and practical method for mono and polymethoxylation of unactivated aryl bromides has been developed; CuCl was used as catalyst, HCOOMe as cocatalyst, and methanolic MeONa as both nucleophile and solvent. This eco-friendly procedure is characterized by operational simplicity, inexpensive substrates (unactivated mono to polybromoarenes), full conversion, and direct recovery of pure MeOH.