Liquid Phase Methanol Research Articles

Liquid phase methanol synthesis by CO2 hydrogenation over Cu-Zn/Z catalysts: Influence of Cd promotion

BackgroundThe current scenario of high CO2 emissions, which is causing global warming and climate change, one of the greatest challenges faced by the global community. One of the most promising ways to recycle CO2 and thus mitigate its emission into the natural environment is the catalytic conversion of CO2 into valuable products such as methanol, hydrocarbons, dimethyl ether (DME), formaldehyde, syngas, alcohols and urea. MethodZeolite supported Cu-Zn bimetallic (Cu-Zn/Z) catalysts were synthesized by co-precipitation method. The synthesized catalysts were doped with different concentration of Cd to investigate the promoting role of Cd. To investigate the physicochemical profile of the calcined Cu-Zn/Z nano-catalysts, various analytical techniques were used. Significant findingsThermal stability of zeolite support was carried out using Thermogravimetric analysis (TGA). TGA data exhibited higher thermal stability of the zeolite support. XRD findings revealed highly dispersed Cd promoted Cu-Zn oxides on the surface of the zeolite support. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate morphology, which indicated the nano size of synthesized catalysts with uniform distribution of metal oxides. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) detected bulk composition of each metal. BET surface studies revealed the mesoporous nature of Cd promoted Cu-Zn/Z catalysts. X-ray Photoelectron Spectroscopy (XPS) revealed the surface chemistry of Cd promoted Cu-Zn/Z catalysts. Activity data showed the active profile of Cd promoted Cu-Zn/Z catalysts for CO2 hydrogenation to methanol by accelerating the methanol synthesis rate from 73 to 157 g.meth/kg.cat.h. Structure-activity studies identified metal-support interactions and Cu stability as the main factors governing the three-phase methanol synthesis rate from CO2 hydrogenation. The importance of Cd promotion was further demonstrated by the fact that activity profile revealed better performance of the current catalysts with recently reported data in the literature.

Accelerating ultrafast processes in hydrogen-bonded complexes under pressure

Acceleration of ultrafast processes is vital in hydrogen-bonded coumarin–methanol complexes for improving the photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs). The traditional methods expedite ultrafast processes individually related to electron injection in DSSCs, namely, internal conversion (IC) or intermolecular charge transfer (inter-CT), by adjusting molecular topologies. We introduce pressure as an external drive to realize the acceleration of both processes simultaneously without changing the configuration. In the definite hydrogen-bonded complexes, the acceleration of IC and inter-CT processes is visualized by in situ high-pressure femtosecond transient absorption spectroscopy. In liquid-phase methanol, the IC and inter-CT processes are actuated effectively from 150.20 to 59.21 fs and 93.95 to 29.05 ps, respectively. The quickening of both processes is attributed to the enhancement of intermolecular hydrogen bonds under pressure. After the pressure-induced methanol phase transition, the rates of IC and inter-CT processes at 3.67 GPa are increased by 36.42% and 80.55% compared to at 1.00 atm. Our study results open an enlightening avenue for boosting the photoelectric conversion efficiency of DSSCs.

ZnO Particles Stabilized in Polymeric Matrix for Liquid-Phase Methanol Synthesis

ZnO supported on hypercrosslinked polystyrene was developed for liquid-phase methanol synthesis. The synthesized catalyst was characterized using the low-temperature nitrogen physisorption, TEM, XPS, XAS, and CO DRIFT methods. The analysis showed that the catalyst has a high specific surface area (720 m2/g) and is characterized by the micro-mesoporous structure typical of the polymer used. The active phase is represented by ZnO species with a hexagonal wurtzite structure. ZnO-HPS showed high activity, selectivity, and stability in liquid-phase methanol synthesis in comparison with the industrial catalyst. The activity of the proposed catalyst was found to be 1.64 times higher than that of the conventional Cu/ZnO/Al2O3.

One-step direct conversion of methane to methanol with water in non-thermal plasma

Achieving methane-to-methanol is challenging under mild conditions. In this study, methanol is synthesized by one-step direction conversion of CH4 with H2O at room temperature under atmospheric pressure in non-thermal plasma (NTP). This route is characterized by the use of methane and liquid water as the reactants, which enables the transfer of the methanol product to the liquid phase in time to inhibit its further decomposition and conversion. Therefore, the obtained product is free of carbon dioxide. The reaction products include gas and liquid-phase hydrocarbons, CO, CH3OH, and C2H5OH. The combination of plasma and semiconductor materials increases the production rate of methanol. In addition, the addition of Ar or He considerably increases the production rate and selectivity of methanol. The highest production rate of methanol and selectivity in liquid phase can reach 56.7 mmol gcat−1 h−1 and 93%, respectively. Compared with the absence of a catalyst and added gas, a more than 5-fold increase in the methanol production rate is achieved.

Preparation of MIL-88B(Fex,Co1−x) catalysts and their application in one-step liquid-phase methanol oxidation to methyl formate using H2O2

The selective oxidation of methanol to methyl formate is one of the most attractive processes to obtain value-added methanol-downstream products. The development of highly efficient and stable catalysts is critical for this transformation. In this study, a series of MIL-88B(Fex,Co1–x) bimetallic catalysts with different Fe/Co molar ratios were prepared through a one-pot hydrothermal method. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption, and inductively coupled plasma-mass spectrometry characterization were performed to elucidate the structure of the catalysts. The activity of the catalysts were assessed in the one-step oxidation of methanol to methyl formate with H2O2 in a liquid-phase batch reactor. The results show that the MIL-88B(Fex,Co1–x) catalysts exhibit uniform needle-like morphologies with an average length and width of 400–600 nm and 100–150 nm, respectively. Co2+ is incorporated into the framework by partially replacing Fe3+ in MIL-88B. Moreover, the catalyst efficiently promoted the conversion of methanol to methyl formate. When MIL-88B(Fe0.7,Co0.3) catalyst was used with a molar ratio of H2O2 to methanol of 0.5 at 80 °C for 60 min, 34.8% methanol conversion was achieved, and the selectivity toward methyl formate was 67.6%. The catalysts also showed great stability with a steady conversion and selectivity even after four cycles. The preliminary oxidation mechanism was also studied. It was determined that H2O2 is first adsorbed on the Fe3+ sites and subsequently activates these sites. Methanol is adsorbed by the O atoms of the framework through hydrogen bonding and is gradually oxidized to formic acid. Subsequently, formic acid reacts with the residual methanol at the Fe3+ and Co2+ Lewis acid sites to form methyl formate.

Monometallic platinum and palladium–based catalysts in the competitive oxidation of methanol over the liquid–phase methanol–ethanol mixtures

This work explored the catalytic performances of monometallic platinum and palladium–based catalysts applied in the competitive oxidation reaction of methanol in presence of ethanol as a possible quality control in counterfeit alcohol production. Pt and Pd over different supports like alumina, SBA–15, as well as faujasite type Y (FAU–Y) and ZSM–5 zeolites were applied in the competitive oxidation reaction of methanol and ethanol (equimolar amounts in 20 mL aqueous solution) with the addition of two kinds of oxidants (hydrogen peroxide (H2O2) and pure O2 gas) for sake of evaluating the alcohols oxidation effect. The results showed that Pt/FAU–Y catalyst had the best performance, due to the molecular size difference between methanol and ethanol and the negligible diffusivity of ethanol through the small pore faujasite, the optimized Pt active sites can be fully accessed by the methanol molecule.

Process Intensification with a Polar Solvent in Liquid Phase Methanol Synthesis

Process Intensification with a Polar Solvent in Liquid Phase Methanol Synthesis

Sensitive and selective methanol biosensor using two-enzyme cascade reaction and fluorometry for non-invasive assessment of intestinal bacteria activity

For understanding the status of intestinal flora non-invasively, methanol (MeOH) has been attracting the attention. In this study, we have developed and compared two different liquid-phase methanol biosensors. One, referred to as the AOD electrosensor, utilized alcohol oxidase (AOD) and an oxygen electrode. It electrochemically measured the decrease in oxygen through AOD-catalyzed oxidation of MeOH. The other, referred to as the AOD-FALDH fluorosensor, exploited a cascade reaction of AOD and formaldehyde dehydrogenase (FALDH) in conjunction with a fiber-optic sensor. It measured increase in the fluorescence from reduced form of β-nicotinamide adenine dinucleotide (NADH) that was a final product of the two-enzyme cascade reaction. Due to the cascade reaction, the AOD-FALDH fluorosensor showed 3 times better sensitivity along with 335 times wider dynamic range (494 nM–100 mM) than those of the AOD electrosensor (1.5–300 μM). The selectivity to MeOH was also improved by the cascade reaction with AOD-FALDH as no sensor output was observed from other aliphatic alcohols than MeOH in contrast to the AOD electrosensor. Although the use of FALDH resulted in the increase in the sensor output from aldehydes, such as acetaldehyde and formaldehyde, considering their concentrations in body fluids, the influence on the sensor output is limited. These results indicate that incorporating the cascade reaction into fluorometry enables enhanced biosensing of MeOH that will be useful for assessment of intestinal flora with little burden.

One-step synthesis of methyl methacrylate from methyl propionate and methanol under mild condition

In recent years, coal-based one-step synthesis of methyl methacrylate (MMA) stimulated researchers’ interest due to the over-capacity of coal chemical industry. However, the high reaction temperature, low yield and selectivity, catalyst deactivation due to carbon deposition, and volatilization and polymerization of formaldehyde have been the challenging problems in this field. In this work, the cascade reactions of methanol dehydrogenation to formaldehyde, aldol condensation between formaldehyde and methyl propionate, and O2-inteerrupted hydrogenation of MMA were resolved via construction of mild and efficient cobalt complex catalyzed interrupted hydrogen borrowing system. Thus, one-step synthesis of MMA from methyl propionate and methanol in liquid phase at 80 °C with yield and selectivity of 25.7% and 92.6% was realized. The cobalt complex activation and methanol dehydrogenation mechanisms were investigated with nuclear magnetic resonance (NMR) characterization, and the C–H bond activation and breakage of methanol was identified as the rate-controlling step through kinetic isotopic effect experiments, which provided new research direction for coal-based synthesis of MMA.

Nuclear dynamics in resonant inelastic X-ray scattering and X-ray absorption of methanol.

We report on a combined theoretical and experimental study of core-excitation spectra of gas and liquid phase methanol as obtained with the use of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The electronic transitions are studied with computational methods that include strict and extended second-order algebraic diagrammatic construction [ADC(2) and ADC(2)-x], restricted active space second-order perturbation theory, and time-dependent density functional theory-providing a complete assignment of the near oxygen K-edge XAS. We show that multimode nuclear dynamics is of crucial importance for explaining the available experimental XAS and RIXS spectra. The multimode nuclear motion was considered in a recently developed "mixed representation" where dissociative states and highly excited vibrational modes are accurately treated with a time-dependent wave packet technique, while the remaining active vibrational modes are described using Franck-Condon amplitudes. Particular attention is paid to the polarization dependence of RIXS and the effects of the isotopic substitution on the RIXS profile in the case of dissociative core-excited states. Our approach predicts the splitting of the 2a″ RIXS peak to be due to an interplay between molecular and pseudo-atomic features arising in the course of transitions between dissociative core- and valence-excited states. The dynamical nature of the splitting of the 2a″ peak in RIXS of liquid methanol near pre-edge core excitation is shown. The theoretical results are in good agreement with our liquid phase measurements and gas phase experimental data available from the literature.

Copper-manganese catalysts with high activity for methanol synthesis

Layered-double hydroxides (LDHs) based on copper, manganese, and aluminum were successfully prepared from sodium-free reactants, with x (Al3+/[Al3++Cu2++Mn2+]) values between 0.24 and 0.35, and y (Cu2+/Mn2+) values between 2.2 and 10.3. Catalysts obtained by calcination of the LDHs were characterized by EXAFS, XANES, XPS, ICP, XRD, TPR, N2O decomposition and BET, and were evaluated in the liquid-phase methanol synthesis reaction from synthesis gas. Characterization revealed that, in a commercial CuZnAl catalyst, the environment of copper is very similar to that prevailing in CuO. In the CuMnAl catalyst that presented the largest methanol synthesis activity, copper is more electron-deficient than in CuO and there is structural disorder beyond the first coordination sphere. TPR characterization suggests that manganese is in the 4+ oxidation state in the oxide precursor of this catalyst. The catalyst with the highest manganese content, y = 2.2, and prepared at higher pH, presented the highest methanol productivity and selectivity of all materials tested, including a commercial conventional CuZnAl catalyst, under our testing conditions. This was credited to the larger surface area of its oxide precursor, which resulted in smaller Cu crystallites and larger copper surface area than in the case of the remaining ones.

Impact of Dense Internals on Fluid Dynamic Parameters in Bubble Column

AbstractIndustrial gas-liquid processes such as oxidation, hydrogenation, Fischer-Trospch synthesis, liquid-phase methanol synthesis, and nuclear fission are exothermic in nature; the reactor of choice for such processes is, therefore, a bubble column equipped with heat exchanging internals. In addition to maintaining the desired process temperature, the heat exchanging vertical tube internals are used to control flow structures and liquid back mixing. The present work reports the experimentally measured gas hold-up, mean liquid velocity and liquid phase turbulent kinetic energy, using the Radioactive Particle Tracking (RPT) technique, in a 120 mm diameter bubble column equipped with dense vertical tube internals covering 23 % of the total cross-sectional area of the column. The effect of superficial gas velocity (44–265 mm/s) on gas hold-up, mean liquid velocity and turbulent kinetic energy is presented and discussed. It has been inferred from the experimental results that the vertical tube internal located at the center of the column plays a vital role in affecting the hydrodynamics when compared to the conventional internal configurations reported in the literature. For the chosen dense internal configuration, the cross-sectional distribution of the gas holdup, mean liquid velocity and turbulent kinetic energy show asymmetry for all the superficial gas velocities investigated. The overall gas holdup and the liquid turbulence increases with an increase in the superficial gas velocity. The strong liquid circulation velocities have been seen upon the insertion of the dense internals.

Electrocatalytic Reduction of Carbon Dioxide Using Graphene/Cotmpyp-Based Coatings

The sharply rising level of atmospheric CO2 is one of the largest environmental concerns facing our civilization today. CO2 is the most significant greenhouse gas that has major effects on the environment such as global warming and ocean acidification. The conversion of CO2 back to useful compounds is a critical goal that would restore balance to earth’s atmosphere. CO2 reduction is possible through chemical catalysis, electrochemistry, photochemistry and biological processes. Chemical catalytic processes generally operate at high temperatures and pressures which lead to high energy cost. Electrochemical methods, however, operate at ambient conditions which offer a simple and effective route for CO2 reduction. The electrocatalytic capabilities toward CO2 reduction of some cobalt porphyrins have been reported in the literature, although at considerable overpotentials and low current densities. The present work aims to assemble an electrocatalytic system composed of cobalt porphyrins and graphene derivatives. Spectroscopic, microscopic and electrochemical methods are used to analyze the interactions occurring between such porphyrins and graphene derivatives, and their effect on CO2 reduction. Such self-assembled systems are formed between 5,10,15,20-Tetrakis(1-methyl-4-pyridinio) porphyrin (CoTMPyP) and graphene oxide (GO). This combination was electrodeposited on electrode surfaces, from aqueous solutions, using concessive cyclic voltammetry scans. Cross-section TEM-EELS images found dense distribution of CoTMPyP between the graphene sheets throughout the coating (figure 1). This arrangement of dense cobalt porphyrins between large conducting graphene sheets leads to enhanced electrocatalytic activity and formation of liquid-phase methanol as determined from GC-MS analysis. The electrodeposited CoTMPyP-GO system showed increased electrochemical activity toward CO2 reduction vs. water reduction (0.7 and 0.3 mA/cm2, respectively, at -1.2V vs. Ag/AgCl), as examined in aqueous 0.1 M Na2CO3 solution at pH 11.5. Figure 1

Graphene Oxide as An Efficient Photocatalyst For Photocatalytic Reduction of CO2 Into Solar Fuel

Photocatalytic reduction of CO2 into solar fuel such as methane and methanol, is an attractive approach to simultaneously solve the energy crisis and global warming problem. Herein, comparative photocatalytic activity of graphene oxide nanosheets have been investigated for photocatalytic reduction of CO2 into methane and methanol in continuous gas and liquid phase photoreactor system. The graphene oxide sheets were prepared according to Tour's method. The chemical composition and optical properties was evaluated through XPS and UV-vis spectroscopy. Graphene oxide nanosheets exhibited maximum amount of 224.87 I¼mol/g.h methanol and 14.8 I¼mol/g.h methane in liquid and gas phase system, respectively. Higher yield of methanol in liquid phase compared to methane in gaseous system can be attributed to dispersion of graphene oxide sheets in water. Hence, graphene oxide nanosheets are efficient photocatalyst for CO2 reduction into methanol. Nevertheless, further research is essential to improve the photostability of graphene oxide sheets for real application of photocatalytic CO2 reduction. © Universiti Malaysia Pahang, Malaysia.

Optimal Design of Gas-Expanded Liquid Ethylene Oxide Production with Zero Carbon Dioxide Byproduct

The concept of ethylene epoxidation over methyltrioxorhenium (MTO) catalyst could save the world from global warming since the epoxidation reaction never produces carbon dioxide as byproduct. Unlike the conventional gas epoxidation reaction with oxygen, this reaction takes place in the (ethylene) gas-expanded liquid solvent phase (methanol) while the reaction oxidant is hydrogen peroxide. The reaction takes place at temperatures and pressures close to the ethylene critical point (Pc = 50.42 bar; Tc = 48.56 °F) (Gas Encyclopedia by Air Liquide, https://encyclopedia.airliquide.com/ethylene). In this paper, an optimized design and operation for MTO based ethylene oxide (EO) production processes has been developed, which has less manufacturing costs compared with the one from the current literature ( Ind. Eng. Chem. Res. 2013, 52, 18−29). The developed EO system could produce 200,000 tons of ethylene oxide per year at a purity of 99.9%. It has two reactors for ethylene epoxidation and hydrogen peroxide decomp...

Investigation of Active Center of Cu‐Based Catalyst for Low Temperature Methanol Synthesis from Syngas in Liquid Phase: The Contribution of Cu+ and Cu0

AbstractLaCuMn catalyst was prepared under different reduction temperature and passivation time, and used to catalyze CO hydrogenation to methanol in liquid phase. The effect of reductive copper species on the catalytic activity and the product distribution was studied. The results showed that the surface content of reductive copper species greatly affect the catalytic activity and the approximate molar ratio of Cu+ to Cu0 was important. The mixture of CuZn/AC‐N2 with only Cu+ and CuZn/AC‐H2 with only Cu0 was utilized for the low temperature methanol synthesis from syngas in liquid phase. It was confirmed that both of the reductive copper species of Cu+ and Cu0 were active species and Cu+ was superior to Cu0. Moreover, the synergic function of Cu+ and Cu0 led to the enhancement of the catalytic activity of Cu based catalyst, and the optimum molar ratio of surface Cu+ to Cu0 was in the range of 3.5 to 4.0.

A comparative study of alcohol oxidation over nanoporous gold in gas and liquid phase

The aerobic oxidation of methanol and ethanol in liquid phase is investigated using unsupported nanoporous gold (npAu) catalysts and compared to gas phase experiments. We pursue the question if this material is still suited as a type of model catalyst even under much more complex conditions in liquid phase. Indeed, npAu is an active catalyst for both liquid and gas phase oxidation of methanol and ethanol with O2 under mild conditions (starting at 40°C). While in case of methanol solely the self coupling product (methyl formate) is detected, the more facile formation of the acetaldehyde in case of ethanol results in the formation of the free aldehyde (acetaldehyde) and the coupling product (ethyl acetate) in similar amounts. To further probe the surface chemistry, cross coupling reactions between both alcohols, as well as the acetaldehyde are performed. As observed also in gas phase experiments, the formation of the surface bonded aldehyde by β-H elimination of the alcoxy species is rate determining.

PdIn intermetallic nanoparticles for the Hydrogenation of CO2 to Methanol

Direct hydrogenation of CO2 to methanol could offer significant environmental benefits, if efficient catalysts can be developed. Here, bimetallic Pd-In nanoparticles show good performance as catalysts for this reaction. Unsupported nanoparticles are synthesised by the thermal decomposition of Pd(acetate)2 and In(acetate)3 precursors in a high boiling point solvent (squalane), followed by reduction using dilute H2 gas (210°C). Adjusting the ratio of the two metallic precursors allow access to 5–10nm nanoparticles with different phase compositions, including metallic Pd(0), In2O3 and intermetallic PdIn. Liquid phase methanol synthesis experiments (50bar, 210°C, H2:CO2=3:1) identify the intermetallic PdIn nanoparticles as the most efficient. The catalysts exhibit around 70% higher methanol rates (normalised to the overall molar metal content) compared to the conventional heterogeneous Cu/ZnO/Al2O3 catalyst (900 and 540μmolmmolPdInorCuZnAl−1h−1, respectively). In addition, the optimum Pd/In catalyst shows an improved methanol selectivity over the whole temperature range studied (190–270°C), reaching >80% selectivity at 270°C, compared to only 45% for the reference Cu/ZnO/Al2O3 catalyst. Experiments showed an improvement in stability; the methanol production rate declined by 20% after 120h run for the optimum PdIn-based compared with 30% for the Cu/ZnO/Al2O3 catalyst (after 25h). The optimum catalyst consists of ∼8nm nanoparticles comprising a surface In-enriched PdIn intermetallic phase as characterised by XRD, HR-TEM, STEM-EDX and XPS. Post-catalysis analysis of the optimum catalyst shows that the same PdIn bimetallic phase is retained with only a slight increase in the nanoparticle size.

2-14 低温液相メタノール合成((4)天然ガス転換技術2,Session 2 天然ガス・メタンハイドレート等)

2-14 低温液相メタノール合成((4)天然ガス転換技術2,Session 2 天然ガス・メタンハイドレート等)

Review of Acetic Acid Synthesis from Various Feedstocks Through Different Catalytic Processes

Acetic acid (AA) has been largely used with a wide range of applications such as a raw material for a synthesis of vinyl acetate monomer, cellulose acetate or acetate anhydrate, acetate ester and a solvent for a synthesis of terephthalic acid and so on. The present paper briefly summarizes the commercialized chemical processes with their Rh or Ir-based catalytic systems in a liquid-phase carbonylation reaction such as Monsanto, Cativa and Acetica processes. In addition, some alternative catalytic systems such as heterogeneous catalysts to produce AA by direct oxidation or indirect carbonylation of dimethyl ether through BP-SaaBre process in a gas-phase reaction to solve some problems such as a difficult separation of homogeneous catalysts in a corrosive reaction medium. Some home-made heterogeneous catalysts such as a rhodium incorporated graphitic carbon nitride (Rh-g-C3N4) and some heterogenized homogeneous catalysts using the supports of tungsten carbide, iron oxide or graphitic carbon nitride containing rhodium complexes were also introduced for the synthesis of AA through a liquid-phase methanol carbonylation reaction to effectively solve the leaching problem of active rhodium metal as well as to mitigate the separation problem of homogeneous catalysts.