Conversion of ethane to ethylene and hydrogen by utilizing carbon dioxide: Screening catalysts

Owing to the necessity of carbon dioxide conversion and exploring new routes for ethylene and hydrogen production, carbon-dioxide-assisted dehydrogenation over alumina-supported catalysts is evaluated in the present contribution. In this regard, the experimental results of a wide range of catalysts at 700 °C and the GHSV of 3600 L_reactants/kg_catalyst.hr are presented and compared. The utilized catalysts showed activity toward the conversion of ethane. However, a few of them showed good selectivity for the production of either ethylene or hydrogen. The catalysts made up of the oxides of cobalt and molybdenum showed very good conversion, selectivity, and yield for ethylene production. Investigating the effect of time on steam on the catalyst performance indicated that these catalysts would be suitable choices in the course of ethylene production. 58% conversion of ethane and 21.9% ethylene yield are the achievements of utilizing the molybdenum-cobalt oxide catalyst. By utilizing rhenium-platinum nickel-potassium catalysts, 100% ethane conversion in tandem with more than 260.0% hydrogen yield was also obtained.     

Dry reforming of ethanol for hydrogen production: Thermodynamic investigation

Thermodynamics of ethanol reforming with carbon dioxide for hydrogen production has been studied by Gibbs free energy minimization method. The optimum conditions for hydrogen production are identified: reaction temperatures between 1200 and 1300 K and carbon dioxide-to-ethanol molar ratios of 1.2–1.3 at 0.1 MPa. Under the optimal conditions, complete conversion of ethanol, 94.75–94.86% yield of hydrogen and 96.77–97.04% yield of carbon monoxide can be achieved in the absence of carbon formation. The ethanol reforming with carbon dioxide is suitable for providing hydrogen-rich fuels for molten carbonate fuel cell and solid oxide fuel cell. The carbon-formed and carbon-free regions are found, which are useful in guiding the search for suitable catalysts for the reaction. Inert gases have a positive effect on the hydrogen and carbon monoxide yields.     

Characteristics of hydrogen production by a plasma–catalyst hybrid converter with energy saving schemes under atmospheric pressure

This paper investigated the production of hydrogen from methane under atmospheric pressure using a plasma–catalyst hybrid converter with emphasis on energy conservation. A spark discharge was used to ionize the hydrocarbon fuel and air mixture with a catalyst to enhance hydrogen production using two energy saving schemes, namely, heat recycling and heat insulation. The experimental results showed that higher methane feeding rate resulted in higher reformate gas temperature and a corresponding increase in methane conversion efficiency. The energy saving systems also enabled the oxygen/carbon ratio to be decreased to reduce oxidation of hydrogen and carbon monoxide and thereby improving the concentrations of hydrogen and carbon monoxide. By heat recycling, a lower methane feeding rate showed an 8.7% improvement in methane conversion efficiency whilst improvement was not apparent with higher methane supply rates due to the already high conversion efficiency. Moreover, it was shown that hydrogen production increased significantly with the reaction from water–gas shifting under the same operation parameters but with high methane selectivity. The best combination resulting in a total thermal efficiency of 77.11% was 10 L/min methane feeding rate and 0.8 O₂/C ratio. With water–gas shifting (S/C ratio=0.5), an 86.26% hydrogen yield, equating to 17.25 L/min hydrogen production rate could be achieved. The equilibrium production rate was calculated using the commercialized HSC Chemistry software (^©ChemSW Software, Inc.). Good correlation was obtained between the calculations and the experimental results.     

High-purity hydrogen gas production by catalytic thermal decomposition using mechanochemical treatment

The objectives of this work, were to produce high-purity hydrogen gas from rice husk by two-step process and to study the effect of nickel hydroxide/nickel acetate/sodium acetate and calcium hydroxide on the concentration of gaseous products. The samples were characterized by X-ray diffraction (XRD) and thermogravimetry-mass spectroscopy (TG/MS). The gaseous products were analyzed by gas chromatography (GC). The results indicated that hydrogen gas was produced from the milled samples by heating at 400–600 °C with the low concentrations of methane, carbon monoxide and carbon dioxide. The highest concentration of hydrogen gas from milled samples with the catalyst, was approximately 95–97 %mol. Furthermore, the milled samples with the carbon dioxide capture agent gave the carbon dioxide concentration, was below 2 %mol.     

Ni–Cu–Zn/MCM-22 catalysts for simultaneous production of hydrogen and multiwall carbon nanotubes via thermo-catalytic decomposition of methane

Pure hydrogen and carbon nanotubes were produced via thermo-catalytic decomposition (TCD) of methane over Ni-loaded MCM-22 catalysts in a vertical fixed-bed reactor. The effect of reaction temperature, gas hourly space velocity (GHSV), Cu/Zn promoter and time on stream on the methane conversion, hydrogen and carbon yields were studied over the synthesized catalysts. The catalytic performance of the 50%Ni–5%Cu–5%Zn/MCM-22 catalyst was found to be highly stable compared to other catalysts. The highest conversion of methane over 50%Ni–5%Cu–5%Zn/MCM-22 catalyst reached 85% with 947% carbon yield. Methane conversion increased on increasing the reaction temperature up to 750 °C and decreased thereafter at higher temperatures. XRD and TEM analysis of the carbon byproduct revealed that graphitic carbon appeared as a major crystalline phase during the reaction. HRTEM results revealed that most of the Ni particles were located on the tip of the carbon nanofibers/nanotubes formed on the spent catalysts. The carbon nanofibres have an average outer diameter of approximately 20–40 nm with an average length of 450–500 nm. Four types of carbon nanofibers were detected and their formation strongly depended on the reaction temperature, time on stream and degree of the interaction between the metallic Ni particle and support. The optimum conditions for CNT production within the experimental ranges were found at a reaction temperature of 750 °C.     

Hydrogen production by biomass gasification in supercritical or subcritical water with Raney-Ni and other catalysts

Gasification of peanut shell, sawdust and straw in supercritical or subcritical water has been studied in a batch reactor with the presence of a series of Raney-Ni and its mixture with ZnCl₂ or Ca(OH)₂. The main gas products were hydrogen, methane, carbon dioxide, and a small amount of carbon monoxide. Different types of Raney-Ni, containing different metal components such as Fe, Mo or Cr, have different influences on the gasification yield and hydrogen selectivity. The catalysis effect can be improved obviously by adding ZnCl₂ or Ca(OH)₂. Increasing the reaction temperature or adding ZnCl₂ and Ca(OH)₂ could improve the mass of H₂ in gas products and reduce the mass of CH₄ and CO₂ at the same time. The possible mechanism is that ZnCl₂ can decompose the biomass particle by accelerating cellulose hydrolyzation in high-temperature water, increasing more specific surface to admit catalysts, while Ca(OH)₂ can absorb CO₂ to produce CaCO₃ deposit, which can drop out from the reactant system, and which will drive the reaction to get more hydrogen. With respect to the biomass conversion to gas product and selectivity of H₂ at low temperature, the series of Raney-Ni has shown many advantages over other catalysts; thus, this kind of catalyst has great potential to be utilized in the hydrogen industry for the gasification of biomass.     

Performance, emission and combustion characteristics of biodiesel fuelled variable compression ratio engine

Experiments has been carried out to estimate the performance, emission and combustion characteristics of a single cylinder; four stroke variable compression ratio multi fuel engine fuelled with waste cooking oil methyl ester and its blends with standard diesel. Tests has been conducted using the fuel blends of 20%, 40%, 60% and 80% biodiesel with standard diesel, with an engine speed of 1500 rpm, fixed compression ratio 21 and at different loading conditions. The performance parameters elucidated includes brake thermal efficiency, specific fuel consumption, brake power, indicated mean effective pressure, mechanical efficiency and exhaust gas temperature. The exhaust gas emission is found to contain carbon monoxide, hydrocarbon, nitrogen oxides and carbon dioxide. The results of the experiment has been compared and analyzed with standard diesel and it confirms considerable improvement in the performance parameters as well as exhaust emissions. The blends when used as fuel results in the reduction of carbon monoxide, hydrocarbon, carbon dioxide at the expense of nitrogen oxides emissions. It has found that the combustion characteristics of waste cooking oil methyl ester and its diesel blends closely followed those of standard diesel.     

Two-dimensional modeling of selective CO oxidation in a hydrogen-rich stream

In this study, carbon monoxide removal by preferential oxidation in a hydrogen-rich stream is simulated between two parallel infinite plates of 150 μm distance. A three-step kinetic is considered that includes carbon monoxide oxidation, hydrogen oxidation and water–gas shift reaction. The walls temperature is in the range of 80–120 °C. The function of this microreactor is to reduce carbon monoxide content from about 2% to below 10 ppm, suitable for use in a PEM fuel cell. Based on the problem conditions, the flow is in the continuum regime and application of the Navier–Stokes equations is admissible. In order to simulate the reacting flow, continuity, conservations of x- & y-momentum, conservation of energy, conservation of species, state equation and reaction rates are simultaneously solved through SIMPLE algorithm by utilizing power-law scheme. Effects of important parameters including walls temperature, steam content, CO content and O₂/CO are assessed. It is observed that increasing walls temperature or oxygen content will increase both CO selectivity and conversion. It is also found that by steam addition, CO conversion is improved without significant change of CO selectivity. These results are in good agreement with previous published data.     

Effect of hydroxy and hydrogen gas addition on diesel engine fuelled with microalgae biodiesel

Owing to high growth rate, being non-edible, and environmental friendliness; microalgae is a promising third generation biodiesel raw material. In this study, hydrogen and hydroxy gas aspirated compression ignition engine which was fuelled with microalgae biodiesel and low sulphur diesel fuel blend were investigated in order to evaluate their combined effect. The results showed that the brake power and torque output of the test engine decreased with microalgae biodiesel usage. Moreover, microalgae biodiesel addition results in lower carbon monoxide and nitrogen oxides emissions, and higher carbon dioxide. The introduction of hydrogen and hydroxy gas compensated the decrement of torque and power output and increment of carbon dioxide emission. The study enlightened that usage of microalgae biodiesel with hydrogen and hydroxy gas addition is a very promising combination from the environmental viewpoint.     

Development of a high-efficiency hydrogen generator for fuel cells for distributed power generation

A collaborative effort between Intelligent Energy and Cal Poly Pomona has developed an adsorption enhanced reformer (AER) for hydrogen generation for use in conjunction with fuel cells in small sizes. The AER operates at a lower temperature (about 500 °C) and has a higher hydrogen yield and purity than those in the conventional steam reforming. It employs ceria supported rhodium as the catalyst and potassium-promoted hydrotalcites to remove carbon dioxide from the products. A novel pulsing feed concept is developed for the AER operation to allow a deeper conversion of the feedstock to hydrogen. Continuous production of near fuel-cell grade hydrogen is demonstrated in the AER with four packed beds running alternately. In the best case of methane reforming, the overall conversion to hydrogen is 92% while the carbon dioxide and carbon monoxide concentrations in the production stream are on the ppm level. The ratio of carbon dioxide in the regeneration exhaust to the one in the product stream is on the order of 10³.     

Steam reforming of volatile fatty acids (VFAs) over supported Pt/Al2O3 catalysts

Volatile fatty acids (VFAs), easily produced using acid fermentation of biomass, were used to generate hydrogen via steam reforming. Three short-chain carboxylic acids (C2-C4) - acetic, propionic and butyric acids - were used as model compounds in addition to VFAs produced in a typical anaerobic batch reactor. Catalytic steam reforming of VFAs using alumina-supported platinum catalysts was studied in a fixed-bed quartz reactor at various temperatures between 300 and 600 °C. The influence of reaction conditions such as temperature, oxygen to carbon ratio (O/C) and gas hourly space velocity (GHSV) was investigated. VFAs were successfully converted to CO_x and hydrogen. A hydrogen yield of up to 70% was achieved, based on typical stoichiometry at 600 °C and a GHSV of 25,000 h⁻¹. Temperature-programmed oxidation (TPO), X-ray diffraction (XRD) and pore size distribution (PSD) were used to characterize coke deposition. Graphitic carbon on catalysts was not identified by XRD, which implies that amorphous coke had formed in the small pores. The catalysts could be reactivated by oxidation and reduction. A detrimental effect on hydrogen yield was observed by adding a small amount of O₂ to the VFA feed, due to the high concentration of oxygen in the feed composition. Steam reforming of real VFAs (S/C = 9) in the acid fermentation of food waste was performed with different GHSVs at a reaction temperature of 600 °C. Conversion of VFAs decreased significantly with increasing GHSV, but the hydrogen selectivity was still above 60%. The conversion pathways of the VFAs to CO_x and hydrogen are most likely complex, particularly due to the variety of the chemical compounds present in the real VFAs. The steam reforming of VFAs was investigated over various noble metal (Ruthenium, Palladium, Rodium, Nickel) catalysts supported on alumina, the specific activity based on the active surface area decreased in the order of Ru > Pd∼Rh > Pt > Ni.     

Selective CO oxidation in H2 streams on CuO/CexZr1−xO2 catalysts: Correlation between activity and low temperature reducibility

Catalysts synthesized by incorporating CuO (7 wt.% of Cu) on six commercial Ce_xZr_1−xO₂ mixed oxides (x = 1, 0.8, 0.68, 0.5, 0.15, 0) have been prepared by conventional wetness impregnation method. These catalysts have been screened for CO oxidation in hydrogen streams (CO-PROX) and characterized by means of XRD, BET, Raman, XPS and H₂-TPR experiments. Activity towards CO oxidation in hydrogen streams has been discussed and correlated with the properties of the catalysts. XRD and Raman analysis of the supports show an increase of oxygen defect as Zr content increase. Below 150 °C the catalysts reducibility measured by H₂-TPR correlates with ceria content in the support, although an increase of Zr content in the support increases considerably the reduction degree of ceria in the 0–600 °C interval. Activity towards CO oxidation in hydrogen streams also correlates with Ce/Cu molar ratio and low temperature reducibility of copper species. Most of the catalysts give complete CO conversion with high selectivity operating with λ = 2. The most active catalysts is CuO supported on pure ceria, which is able to oxidize completely CO in the interval 96–164 °C, with maximum selectivity of 90%. On the other hand, the operation window becomes narrower as Zr content in the supports increases.     

Short contact time catalytic partial oxidation of biogas – A comprehensive study on CO2 and N2 dilution

The short contact time catalytic partial oxidation of methane diluted with nitrogen and/or carbon dioxide to act as a surrogate for biogas conversion was carried out. Experiments were carried out under varying operating conditions to determine the possible use of the products in pyrolysis.Carbon dioxide has a larger effect on the product selectivities and back face temperature of the catalyst compared to nitrogen for equal dilutions. Carbon dioxide is consumed in the reactor whereas nitrogen is not. Since carbon dioxide likely takes part in endothermic reactions, the temperature of the catalyst is lower as is the conversion of methane and selectivity to carbon monoxide and hydrogen.The product stream is at an appropriate composition and temperature for subsequent use in a pyrolysis reactor. The presence of hydrogen and carbon monoxide will result in the removal of oxygen from bio-oils that are produced in the pyrolysis reactor.     

Hydrogen production by biomass gasification in supercritical or subcritical water with Raney-Ni and other catalysts

Gasification of peanut shell, sawdust and straw in supercritical or subcritical water has been studied in a batch reactor with the presence of a series of Raney-Ni and its mixture with ZnCl₂ or Ca(OH)₂. The main gas products were hydrogen, methane, carbon dioxide, and a small amount of carbon monoxide. Different types of Raney-Ni, containing different metal components such as Fe, Mo or Cr, have different influences on the gasification yield and hydrogen selectivity. The catalysis effect can be improved obviously by adding ZnCl₂ or Ca(OH)₂. Increasing the reaction temperature or adding ZnCl₂ and Ca(OH)₂ could improve the mass of H₂ in gas products and reduce the mass of CH₄ and CO₂ at the same time. The possible mechanism is that ZnCl₂ can decompose the biomass particle by accelerating cellulose hydrolyzation in high-temperature water, increasing more specific surface to admit catalysts, while Ca(OH)₂ can absorb CO₂ to produce CaCO₃ deposit, which can drop out from the reactant system, and which will drive the reaction to get more hydrogen. With respect to the biomass conversion to gas product and selectivity of H₂ at low temperature, the series of Raney-Ni has shown many advantages over other catalysts; thus, this kind of catalyst has great potential to be utilized in the hydrogen industry for the gasification of biomass.     

Pyrolysis and oxidation of ethyl methyl sulfide in a flow reactor

The reactions and kinetics of ethyl methyl sulfide (CH₃CH₂SCH₃, abbreviation CCSC), a simulant for the chemical warfare agent sulfur mustard, were studied at temperatures of 630–740 °C, under highly diluted pyrolysis and oxidation conditions at one atmosphere in a turbulent flow reactor. The loss of the ethyl methyl sulfide and the formation of intermediates and products were correlated with time and temperature. Destruction efficiencies of 50% and 99% were observed for pyrolysis and oxidation, respectively, at 740 °C with a residence time of 0.06 s. For pyrolysis, ethylene, ethane, and methane were detected at significant levels. In addition to these species, carbon monoxide, carbon dioxide, sulfur dioxide, and formaldehyde were detected for oxidation. Conversions of ethyl methyl sulfide were observed to be significantly slower than observed previously for diethyl sulfide; explanations for this observation are postulated, based on: (1) lower hydrogen abstraction rates or on (2) lower hydrogen atom production as a result of thermal decomposition pathways. Initial decomposition reactions and production pathways for important species observed in the experiments are discussed on a basis of thermochemistry.     

A Survey on Various Carbon Sources for Biological Hydrogen Production via the Water-Gas Reaction Using a Photosynthetic Bacterium (Rhodospirillum rubrum)

Growth model of anaerobic photosynthetic bacteria on various carbon sources for fermentative hydrogen production growth from synthesis gas was investigated. It was found that the rate of utilization of carbon monoxide (CO) by Rhodospirillum rubrum on acetate was growth related. A biologically based water-gas shift reaction was catalyzed by the specific bacterium at ambient temperature to convert the gaseous substrate, CO to carbon dioxide, while simultaneously convert water to a useful product, molecular hydrogen. Experiments were conducted to measure the specific CO uptake and hydrogen production rates. Also, effect of initial organic substrate concentration was investigated. The microorganism was grown on formate, acetate, malate, glucose, fructose, and sucrose. The modified Teissier and Contois equations were further developed for the growth model based on existing theory and experimental data. It was also found that the improvement in the yield of hydrogen production using acetate as a suitable substrate for R. rubrum, resulted in 0.87 mmole H ₂ /mmole CO. The obtained hydrogen yield of R. rubrum on acetate was 87% of stoichiometric conversion. The main objective of this research was to demonstrate that the biological hydrogen production may efficiently be implemented as an alternative energy for fossil fuel replacement in the future.     

Continuous supercritical water gasification of isooctane: A promising reactor design

A new design of supercritical water gasification system was developed to achieve high hydrogen gas yield and good gas–liquid flow stability. The apparatus consisted of a reaction zone, an insulation zone and a cooling zone that were directly connected to the reaction zone. The reactor was set up at an inclination of 75° from vertical position, and feed and water were introduced at the bottom of the reactor. The performances of this new system were investigated with gasification of isooctane at various experimental conditions – reaction temperatures of 601–676 °C, residence times of 6–33 s, isooctane concentrations of 5–33 wt%, and oxidant (hydrogen peroxide) concentrations up to 4507 mmol/L without using catalysts. A significant increase in hydrogen gas yield, almost four times higher than that from the previous up-down gasifier configuration (B. Veriansyah, J. Kim, J.D. Kim, Y.W. Lee, Hydrogen Production by Gasification of Isooctane using Supercritical Water, Int. J. Green Energy. 5 (2008) 322–333) was observed with the present gasifier configuration. High hydrogen gas yield (6.13 mol/mol isooctane) was obtained at high reaction temperature of 637 °C, a low feed concentration of 9.9 wt% and a long residence time of 18 s in the presence of 2701.1 mmol/L hydrogen peroxide. At this condition, the produced gases mainly consisted of hydrogen (59.5 mol%), methane (14.8 mol%) and carbon dioxide (22.0 mol%), and a small amount of carbon monoxide (1.6 mol%) and C₂–C₃ species (2.1 mol%). Reaction mechanisms of supercritical water gasification of isooctane were also presented.     

Comparative performance studies of a 4-stroke CI engine operated on dual fuel mode with producer gas and Honge oil and its methyl ester (HOME) with and without carburetor

In order to meet the energy requirements, there has been growing interest in alternative fuels like biodiesels, methyl alcohol, ethyl alcohol, biogas, hydrogen and producer gas to provide a suitable diesel oil substitute for internal combustion engines. Biomass is basically composed of carbon, hydrogen and oxygen. A proximate analysis of biomass indicates the volatile matter to be between 60–80% and 20–25% carbon and the rest, ash. The first part of sub-stoichiometric oxidation leads to the loss of volatiles from biomass and is exothermic; it results in peak temperatures of 1400–1500 K and generation of gaseous products like carbon monoxide, hydrogen in some proportions and carbon dioxide and water vapor, which in turn are reduced in part to carbon monoxide and hydrogen by the hot bed of charcoal generated during the process of gasification. Therefore, solid biomass can be converted into a mixture of combustible gases, and subsequently utilized for combustion in a CI engine. Producer gas, if used in dual fuel mode, is an excellent substitute for reducing the amount of diesel consumed by the CI engine. Downdraft moving bed gasifiers coupled with an IC engine are a good choice for moderate quantities of available biomass, up to 500 kW of electric power. Vegetable oils present a very promising alternative to diesel oil since they are renewable and have similar properties. Vegetable oils offer almost the same power output with slightly lower thermal efficiency when used in diesel engines [1], [2], [3], [4], [5], [6], [7]. Research in this direction with edible oils have yielded encouraging results, but their use as fuel for diesel engines has limited applications due to higher domestic requirement [8], [9], [10]. In view of this, Honge oil (Pongamia Pinnata Linn) is selected and its viscosity is reduced by the transesterification process to obtain Honge oil methyl ester (HOME). Since vegetable oils produce higher smoke emissions, dual fuel operation could be adopted in order to improve their performance. A gas carburetor was suitably designed to maximize the engine performance in dual fuel mode with Honge oil–producer gas and HOME–producer gas respectively. Thus bio-derived gas and vegetable oil, when used in a dual fuel mode with carburetor, resulted in better performance with reduced emissions.     

Oxygen-enhanced water gas shift over ceria-supported Au–Cu bimetallic catalysts prepared by wet impregnation and deposition–precipitation

Au–Cu/ceria bimetallic catalysts were prepared incorporating Au by incipient wetness impregnation (IWI) and deposition-precipitation (DP) methods (with loadings of 1 wt.% and 7 wt.% of Au and Cu, respectively). The as-prepared catalysts were characterized by techniques such as BET, XRD, Raman, XPS, H₂-TPR, CO-TPD and Oxygen Storage Capacity (OSC) measurements. The results indicated a good dispersion of gold and copper for copper ceria catalyst and Au–Cu bimetallic catalysts. Addition of Au to CuO/CeO₂ increases highly the capacity to release lattice oxygen to oxidized CO at low temperatures compared to pure CuO/CeO₂. Au/CeO₂ and Au–CuO/CeO₂ catalyst prepared by DP show higher OSC value than counterparts prepared by IWI, either at 120 and 250 °C. Also, gold-containing catalysts prepared by DP show lower temperature of reduction that the samples prepared by IWI as a consequence of the higher dispersion of gold in the former samples. The presence of gold at different oxidation states was observed by XPS analysis. Preparation method strongly affects to the atom ratio of Au and Au + Cu with respect to surface ceria. The gold incorporation method was a key factor that enhances the redox properties and activity in both WGS and OWGS reactions. The present study shows the gas phase oxygen enhanced the activity of monometallic CuO/ceria and bimetallic Au–Cu/ceria prepared by IWI and DP methods in both WGS and OWGS reactions. AuCC catalyst prepared by DP shows higher hydrogen yield and also higher CO conversion than other prepared by IWI during OWGS reaction.     

Steam reforming behavior of methanol using paper-structured catalysts: Experimental and computational fluid dynamic analysis

Copper–zinc oxide (Cu/ZnO) catalyst powders were impregnated into paper-structured composites (catalyst paper) using a papermaking process. The paper-structured catalyst was subjected to the methanol steam reforming (MSR) process and exhibited excellent performance compared with those achieved by pellet-type or powdered catalyst. The catalyst paper demonstrated a relatively stable gas flow as compared to catalyst pellets. Furthermore, the MSR process was simulated by computational fluid dynamic (CFD) analysis, and the heat conductivity influence of the catalyst layer was investigated. Higher heat conductivity contributed to both higher methanol conversion and lower carbon monoxide concentration; localization of heat and chemical species such as hydrogen and carbon dioxide were improved, resulting in suppression of reverse water–gas shift reaction. The CFD analysis was applied to the design of a catalyst layer in which a suitable shape was suggested, where carbon monoxide formation was further suppressed without a decrease in the methanol conversion.