Methanol Formation Research Articles

Improved Light Hydrocarbon, Furans, and BTEX Production from the Catalytic Assisted Pyrolysis of Agave salmiana Bagasse over Silica Mesoporous Catalysts

The pyrolysis of the biomass Agave salmiana bagasse (10 K/min, ambient to 700 °C) was investigated in the absence and presence of Aerosil and MCM-41 catalysts. MCM-41 was synthetized using a typical hydrothermal method and characterized with XRD, SAXS, SEM, TEM, and nitrogen physisorption to confirm the presence of unidimensional 3.4 nm diameter pores. Pyrolysis products were monitored online with mass spectrometry (MS), analyzing the production of 29 different compounds, clustered in several groups, namely, olefins (ethene, 2-butene, 1,3-butadiene), oxygenated compounds (methanol, 2-methylbutanol, acetic acid), furan derivatives (furan, furfural, 2-methylfurane), and aromatic compounds (BTEX). Complete decomposition of the cellulose and hemicellulose content of the biomass was observed at temperatures below 400 °C. Lignin decomposition was completed by 550 °C. Catalyst-assisted pyrolysis showed reduced acetic acid and methanol formation with Aerosil and MCM-41. The use of Aerosil does not affect the overall production of olefins, yet increases benzene yield, while reducing the production of phenol, furan, and furan derivatives. With MCM-41, there is increased production of olefins, furan, furan derivatives, cyclohexanone and BTEX, yet phenol production is decreased. At temperatures below 400 °C, the product formation pattern is comparable to non-catalytic pyrolysis.

One-step synthesis of methanol and hydrogen from methane and water using non-thermal plasma and Cu-Mordenite catalyst

In this study, the copper-mordenite zeolite (Cu-MOR) and non-thermal plasma were used to produce methanol and hydrogen from methane and water at low temperature (120 °C) without CO2 formation. Energy efficiency for methanol and hydrogen were 68.8 mmol·kJ−1 and 562.3 mmol·kJ−1, respectively, and the selectivity of methanol in liquid products reached 86%. The reaction mechanism likely involves methane being excited to methyl (·CH3) and hydrogen radicals (·H) under DBD plasma conditions, which can then adsorb on the catalyst surface at the Cu2-(μ-O)2+ active sites, accompanied by water co-adsorption to facilitate formation and desorption of methanol. XPS analysis showed that with the prolongation of reaction time, Cu2-(μ-O)2+ was reduced to Cu+ and Cu(II) hydroxide, and the catalyst had carbon deposition, resulting in the decrease of catalytic activity. It is also worth noting that in an oxygen atmosphere, Cu2-(μ-O)2+ regenerates rapidly and eliminates catalyst carbon deposits. Trace oxygen was introduced into the reactor, and the reaction was carried out for 30 h, and the catalytic activity did not decrease.

Photoelectrochemical properties of Cu2O/PANI/Si-based photocathodes for CO2 conversion

The present study was aimed at converting carbon dioxide (CO2) into value-added products such as methanol, which can provide not only a potential solution for controlling the carbon dioxide concentration level in the atmosphere but also can offer an alternative approach for the production of renewable energy sources. From this perspective, various hybrid photoelectrocatalysts were synthesized, characterized and used as photocathodes for photoelectrochemical (PEC) reduction of carbon dioxide to methanol in an aqueous medium under visible light irradiation. Flat silicon (Si) and pyramidal textured silicon (SiPY) substrates, covered with polyaniline (PANI) with or without sensitization with copper (I) oxide (Cu2O) particles, were investigated. It was observed that the combination of PANI and copper (I) oxide greatly increased PEC carbon dioxide reduction to methanol owing to the enhancement in the carbon dioxide chemisorption capacity by the photocathode surface and at the same time facilitated the separation of photogenerated electron–hole (e−/h+) pairs. The PEC results demonstrated that the applied potential impacts the photocurrent stability. Sensitization with copper (I) oxide effectively separated the photogenerated e−/h+ pairs and, therefore, enhanced the PEC carbon dioxide reduction activity of the hybrid photocatalyst. The best faradaic efficiency for methanol formation reached 57.66%, which was recorded when the copper (I) oxide/PANI/SiPY heterostructure was used as a photocathode at an applied potential of −1.2 V against the saturated calomel electrode.

Elucidating the promoting role of Ca on PdZn/CeO2 catalyst for CO2 valorization to methanol

The viability of catalyzed CO2 conversion routes strongly depends on improving the catalytic performance and understanding of the process. Herein, we investigate the effect of Ca loading on PdZn/CeO2 catalysts prepared using the sol–gel chelatization method for CO2 hydrogenation to methanol. A remarkable improvement in catalyst performance was revealed with the optimum amount of Ca (0.5 wt%) in synergetic cooperation with the PdZn alloy (main active phase for the CO2 hydrogenation to methanol reaction), compared to the Ca-free counterpart. The following key performance indicators are attained at 230 °C, 20 bar, and 2400 h−1 GHSV for the optimized catalyst: 16 % CO2 conversion, > 93 % methanol selectivity, and ∼ 124 g/kgcat/h methanol space–time yield. The overall catalytic performance observed is attributed to the optimum Ce3+/Ce4+ ratio, Ca2+ promotion, surface area, pore volume, and basic sites, as revealed by various characterization techniques. Results shown here indicate that the presence of Ca in the vicinity of the PdZn active enhances basicity, creates oxygen vacancies, and phase may have improved the spill-over ability of H2, consequently favoring CO2 activation and methanol formation.

Hydrophobic Polyhedral Oligomeric Silsesquioxane Support Enhanced Methanol Production from CO2 Hydrogenation.

The abundance of CO2 from the cement industry, power generation, petroleum production, and combustion of biomass makes it a readily available feedstock to produce chemicals and materials, although it has yet to achieve optimal development. Even though syngas (CO + H2) hydrogenation to methanol is an established industrial process, when the same catalytic system based on Cu/ZnO/Al2O3 is employed with CO2, the water formed as a byproduct reduces the activity, stability, and selectivity of the process. Here, we explored the potential of phenyl polyhedral oligomeric silsesquioxane (POSS) as a hydrophobic support of Cu/ZnO for direct CO2 hydrogenation to methanol. Mild calcination of the copper-zinc-impregnated POSS material affords the formation of CuZn-POSS nanoparticles with Cu and ZnO homogeneously dispersed with an average particle size of 7 and 15 nm supported on O-POSS and D-POSS, respectively. The composite supported on D-POSS was able to reach a 3.8% yield of methanol with a 4.4% of CO2 conversion and with selectivity as high as 87.5% within 18 h. The structural investigation of the catalytic system reveals that CuO/ZnO are electron withdrawers in the presence of the siloxane cage of POSS. The catalytic system metal-POSS is stable and recyclable under H2 reduction and CO2/H2 conditions. We tested the use of microbatch reactors in heterogeneous reactions as a rapid and effective tool for catalyst screening. The increased number of phenyls in the structure of POSS results in an increased hydrophobic character that plays a decisive role in the methanol formation after comparison with CuO/ZnO supported on reduced graphene oxide with 0% selectivity to methanol under the study conditions. The materials were characterized using scanning electron microscopy, transmission electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Fourier transform infrared analysis, Brunauer-Emmett-Teller specific surface area analysis, contact angle, and thermogravimetry. The gaseous products were characterized by gas chromatography coupled with thermal conductivity detectors and flame ionization detectors.

Evolution of Active Oxygen Species Originating from O2 Cleavage over Fe-FER for Application in Methane Oxidation

Here, we show a spectroscopic study of the formation and oxidation properties of α-oxygen originating from O2 dissociation over binuclear Fe(II) structure in Fe-ferrierite. The investigation of its formation, stability, and methane oxidation properties toward methanol formation at elevated temperatures was confirmed by in situ FTIR spectroscopy and mass spectrometry. For a deeper insight into the redox properties of Fe centers embedded in ferrierite, Mössbauer and X-ray adsorption spectroscopies were used as complementary methods. In situ FTIR spectroscopy and activity test results recorded at elevated temperatures convenient for potential industrial applications (through-flow reactor, 220 °C) showed that binuclear Fe(II) centers in FER can split O2 and form stable species [Fe(IV)=O]2+ active in three consecutive cycles in methane to methanol oxidation. Those results were confirmed by changes in the values of hyperfine parameters of iron species in ferrierite in Mössbauer spectra and by changes in the Fe K-edge XAS spectrum recorded under redox conditions.

Electrocatalytic methane direct conversion to methanol in electrolyte of ionic liquid

The direct conversion of methane (CH4) to methanol (CH3OH) is of great significance for efficiently utilizing biogas and natural gas, in which the activation of CH4 under mild conditions with high selectivity of CH3OH in products is challenging. The advantage of electrocatalytic system besides CH4 activation is that could provide active oxygen species in situ. However, whether the sorts of active oxygen species could affect the methane conversion is still unexplored. In this study, a non-diaphragm electrochemical bath with an aprotic ionic liquid [BMIM]BF4 as supporting electrolyte was setup, in which superoxide radicals (·O2−) and peroxide anions (O22−) were generated through oxygen reduction reaction (ORR) on cathode while CH4 was activated on anode with a V2O5-based catalyst (Ov-V2O5). Methanol and ethanol were identified as the liquid conversion products of CH4, and the average formation rate of 352.5 μmol gcat−1h− 1 for CH3OH with Faraday efficiency of 61.1% were obtained under the optimized conditions. Density function theory (DFT) calculation results suggest that the introduce of V4+ sites in Ov-V2O5 enhanced the chemisorption of CH4 molecules on anode surface, and the active oxygen species are involved in the formation of methanol and ethanol.

Design of Flame‐Made ZnZrOx Catalysts for Sustainable Methanol Synthesis from CO2

AbstractMixed zinc‐zirconium oxides, ZnZrOx, are highly selective and stable catalysts for CO2 hydrogenation to methanol, a pivotal energy vector. However, their activity remains moderate, and descriptors to design improved systems are lacking. This work applies flame spray pyrolysis (FSP), a one‐step and scalable method, to synthesize a series of ZnZrOx catalysts, and systematically compares them to coprecipitated (CP) analogs to establish deeper synthesis–structure–performance relationships. FSP systems (up to 5 mol%) generally display a threefold higher methanol productivity compared to their CP counterparts. In‐depth characterization and theoretical simulations show that, unlike CP, FSP maximizes the surface area and formation of atomically dispersed Zn2+ sites incorporated in lattice positions within the ZrO2 surface, which is key to improving performance. Analysis by in situ electron paramagnetic resonance (EPR) spectroscopy reveals that the specific architecture of the flame‐made catalyst markedly fosters the generation of oxygen vacancies. Together with surrounding Zn and Zr‐O atoms, the oxygen vacancies create active ensembles that favor methanol formation through the formate path while suppressing undesired CO production, as confirmed by kinetic modeling. This study elucidates the nature of active sites and their working mechanism, pushing forward ZnZrOx‐catalyzed methanol synthesis by providing a new benchmark for this cost‐effective and earth‐abundant catalyst family.

High-Pressure Pulsing of Ammonia Results in Carbamate as Strongly Inhibiting Adsorbate of Methanol Synthesis over Cu/ZnO/Al2O3

The active site of the industrially used Cu/ZnO catalyst for the formation of methanol is controversially debated to date. Ammonia has been used as a probe molecule as it was found to inhibit methanol synthesis in CO2-containing synthesis gas. Herein, we investigate the poisoning effect using an industrial-type Cu/ZnO/Al2O3 catalyst synthesized by co-precipitation. During steady-state methanol synthesis in a CO2/CO/H2 synthesis gas, isobaric trimethylamine (TMA) and ammonia injections poisoned methanol formation reversibly, with the poisoning of ammonia being significantly stronger than that of TMA. Based on DFT calculations, a mechanism of ammonia poisoning was derived: ammonia activation takes place on adsorbed oxygen or hydroxyl groups, followed by the reaction with CO2 forming a stable carbamate on the active site. Further hydrogenation of the carbamate to methylamine was calculated to exhibit high barriers, thus being rather slow, explaining why ammonia poisoning has a long-term effect, as TMA cannot form a strongly bound carbamate species exclusively acting as weakly bound site-blocking species.

Electron withdrawing ligands inhibit oxygen transport by Al+: temperature-dependent kinetics of AlO+/(O2)AlO+ + H2/CH4

Al+ has been shown to enable the oxygen atom transfer (OAT) to convert methane to methanol at thermal energies through a unique, barrierless mechanism. Quantum chemical calculations suggested that the efficacy of methanol formation relative to other product channels could be tuned by the presence of electron-withdrawing or -donating groups. Here, the kinetics of AlO+, which has no electron-withdrawing group, and of (O2)AlO+, which includes an electron-withdrawing group, reacting with CH4 or with H2 are studied using a selected-ion flow tube apparatus. In all cases, AlO+ yields the OAT product (CH3OH or H2O) in addition to the hydrogen atom transfer (HAT) product, while (O2)AlO+ yields only the HAT product; the electron-withdrawing O2 group has inhibited oxidation as predicted.

A review on a novel method for aging evaluation of transformer insulating paper based on methanol

AbstractThe insulation paper is a crucial factor for evaluating the insulation status of transformers. The traditional evaluation methods for insulation paper are dissolved gas component content analysis (CO and CO2) and furfural (2‐FAL) content analysis in oil. The detection principle of the former leads to its low accuracy, while the field application effect of the latter is not ideal due to the easy oxidation of furfural and low content. Methanol, result of its good stability and high production compared with other marker products (CO, CO2, 2‐FAL) has been investigated as a novel marker for aging evaluation of transformer insulating paper in recent years. The results of the investigation indicated that there is a good correlation between the content of methanol in oil and the degree of polymerization under laboratory conditions, which reflected the insulation aging state of the transformer insulating paper more accurately. This paper summarizes the current research status of methanol formation mechanism, detection methods and aging evaluation in insulating oil, and points out the key problems to be solved and development prospects, hoping to provide relevant reference for aging evaluation of oil immersed power transformer.

Comprehensive assessment of methanol as an alternative fuel for spark-ignition engines

A promising pathway to defossilize the operation of spark-ignition engines is to use methanol as a fuel. This clean alternative liquid energy carrier offers major efficiency and emission benefits compared to gasoline. Its high knock-resistance and high heat of vaporization allow knock-free operation at high compression ratios while maintaining low emissions of nitrogen oxides. In addition, it is the simplest alcohol to synthesize and the distribution infrastructure for existing liquid fuels can be used. Previous research on mixture formation and combustion of methanol in passenger car sized spark-ignition engines is limited, reported on various experimental configurations, and mainly focused on one particular aspect. This study sets out to provide a coherent evaluation of the mixture formation and performance of methanol in a spark-ignition engine in comparison to gasoline by successively addressing and combining fundamental and optical spray measurements, engine experiments and complementing numerical analyses all with matching boundary conditions for these aspects. First, a theoretical analysis regarding the primary spray break-up behavior was performed using methanol and the gasoline surrogate iso-octane, which showed a comparable atomization performance between the two fuels. This theoretical result was then experimentally validated under realistic engine operating conditions on a low-pressure chamber by means of shadowgraph imaging. These investigations showed no notable differences in spray penetration length and spray angle between methanol and gasoline under the same boundary conditions. However, under realistic engine operation, the spray penetration length of methanol increased by up to 64.5% due to the increased injection duration required because of its lower energy content. In a next step, methanol was experimentally studied on a thermodynamic single-cylinder research engine with a compression ratio of 10.8. Using the same fuel injector, the combustion and emission behavior was investigated in comparison with gasoline. A load variation at an engine speed of 2500 1/min and a variation of the relative air/fuel ratio at the same engine speed and a net indicated mean effective pressure of 16 bar were performed. Depending on the engine load, methanol achieved 7%–24% higher net indicated efficiencies and a 9 bar higher maximum load compared to gasoline. At lean-burn operation, methanol not only enabled higher net indicated efficiencies exceeding 45%, however, also an extended lean-burn limit of 0.1 units. The experimental engine investigations were complemented with 0D/1D simulations, which showed that especially the wall heat transfer and the burn duration are significantly lower in the case of methanol. Finally, 3D computational fluid dynamics simulations were performed using a newly developed methanol spray model which showed that an increased fuel mass impinges the combustion chamber walls with methanol. However, toward the end of compression, the methanol wall film dropped to the level of gasoline.

Simulation and optimization of water gas shift process in ammonia plant: Maximizing CO conversion and controlling methanol byproduct

The water gas shift reaction is one of the most important reactions in ammonia production plants for purifying hydrogen streams from carbon monoxide. This reaction occurs in two consecutive reactors at high and low temperatures. In the current study, the simulation was first carried out for these two reactors in one of the ammonia production units, and then the process variables were optimized to maximize hydrogen production in three states: one that was relatively near-equilibrium, one that was far from equilibrium and one that was near the end of the run. Methanol formation as a byproduct was also identified during process evaluation as a crucial limitation. The optimization results in all three modes indicate that maximum carbon monoxide conversion could be achieved during the catalyst lifetime if the reactors operate at low temperature and pressure at the start-up. As the catalyst lifetime increases, the inlet temperature and pressure must be increased to keep the catalyst active.

Photo-assisted thermal catalysis for methanol synthesis from methane oxidation on Cu-MOR/g-C3N4

Methanol synthesis from methane oxidation at low reaction temperature on Cu-zeolites is a hot topic recently. However, methanol yield is low due to the high energy barrier of methane activation. In this work, we tried to study photothermal catalysis for methanol synthesis from methane oxidation by using O2 as the oxidant on Cu-MOR/g-C3N4, in which g-C3N4 is an absorbent under visible light. Methanol synthesis from methane oxidation on Cu-MOR/g-C3N4 is photoassisted thermal catalysis. The maximum methanol yield under visible light is 3.09 μmol h−1 gcat−1 at the reaction temperature of 200 ℃, 1 atm and 24/3/8 CH4/O2/H2O, which is 1.85 times by thermal catalysis. The reason is that the interaction between Cu-MOR and g-C3N4 is conducive to methanol formation. On the other hand, part of O2 is reduced to O2− on g-C3N4 under visible light, and the oxidation capacity of O2− is greater than of O2. The result will be useful for the design of methanol synthesis from methane oxidation at low reaction temperature.

Redox Behavior of In−O−Ti Interface for Selective Hydrogenation of CO2 to CO in Doped In−TiO2 Catalyst

AbstractIn the CO2 hydrogenation reaction, selective synthesis of CO at low temperature and high pressure is needed to integrate the reverse water gas shift reaction with Fischer‐Tropsch synthesis. Here, we show that a mixed oxide catalyst prepared by doping indium (In) into TiO2 produces CO with the formation rate of 22 μmol g−1 s−1. The CO selectivity was more than 99 % at 350 °C and 3 MPa pressure. Moreover, the catalyst was durable for over 100 h on stream. During reaction the interfacial In3+−O−Ti4+ sites were first reduced in presence of H2 and then oxidized back with CO2 producing CO. Because of the redox mechanism, the formation of methanol and methane was limited. This study shows the development of a promoter‐free oxide catalyst for CO2 hydrogenation and the importance of the redox property at the oxide interface for selective hydrogenation of CO2 to CO under unfavorable conditions.

Effective CO2 Capture and Selective Photocatalytic Conversion into CH3OH by Hierarchical Nanostructured GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg.

The attenuation of greenhouse gases, especially CO2, as one of the main causes of global warming and their conversion into valuable materials are among the challenges that must be met in the 21st century. For this purpose, hierarchical ternary and quaternary hybrid photocatalysts based on graphene oxide, TiO2, Ag2O, and arginine have been developed for combined CO2 capture and photocatalytic reductive conversion to methanol under visible and UV light irradiation. The material's band gap energy was estimated from the diffuse reflectance spectroscopy (DRS) Tauc analysis algorithm. Structural and morphological properties of the synthesized photocatalysts were studied using various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The calculated band gaps for GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg were 3.18 and 2.62 eV, respectively. This reduction in the band gap showed that GO-TiO2-Ag2O-Arg has a significant visible light photocatalytic ability. The investigation of CO2 capture for the designed catalyst showed that GO-TiO2-Ag2O-Arg and GO-TiO2-Ag2O have high CO2 absorption capacities (1250 and 1185 mmol g-1, respectively, at 10 bar and 273 K under visible light irradiation). The amounts of methanol produced by GO-TiO2-Ag2O and GO-TiO2-Ag2O-Arg were 8.154 and 5.1 μmol·gcat1·h-1 respectively. The main advantages of this study are the high efficiencies and selectivity of catalysts toward methanol formation. The reaction mechanism to understand the role of hybrid photocatalysts for CO2 conversion is deliberated. In addition, these catalysts remain stable during the photocatalytic process and can be used repeatedly, proving to be enlightening for environmental research.

Effects of Al distribution in the Cu-exchanged AEI zeolites on the reaction performance of continuous direct conversion of methane to methanol

The effects of the organic structure-directing agent (OSDA) with or without Na cations for the synthesis of AEI zeolite on the location and content of the Al atoms in the framework as well as the Cu speciation and acidic features of the exchanged Cu/AEI zeolite catalysts and their catalytic properties in the continuous direct conversion of methane to methanol (cDMTM) were investigated. The AEI zeolite synthesized with Na cations led to more Al and a higher percentage of Al pairs than the one prepared without Na cations. Consequently, the Cu/AEI zeolite catalysts synthesized with Na cations exhibited lower apparent activation energy of methane conversion, higher methanol formation rate, and less stable ability in the cDMTM reaction due to the more active dicopper species and higher acid amount than those prepared without Na cations. Adjustment of the close Al content in the framework of the two AEI zeolites by calcination, the Cu/AEI zeolite synthesized with Na cations evidenced a higher methanol selectivity and more stable reaction performance because of the different relationship between Cu species and acid sites, such as the distance, caused by the Al distribution. The methanol formation rate of 27.3 µmol·g−1·min−1 with about 50% selectivity and stable performance in the cDMTM reaction at 350 °C were obtained. Moreover, the stability of both 5Cu/AEI zeolite catalysts could be upgraded by further calcination to diminish the acid amount, the high methanol formation rate of the 5Cu/AEI zeolite synthesized with Na cations was maintained and the reaction stability was newly attained. The 5Cu/AEI zeolite synthesized without Na cations, merely the stable performance was reached, while the methanol formation rate and selectivity seriously declined. This work contributed to the development of AEI zeolite with different Al distributions and its significant impacts on the Cu speciation and acidic properties, thus providing a valuable strategy to obtain a robust Cu/AEI zeolite catalytic system for efficient and stable methanol production from methane.

Carbon coated In2O3 hollow tubes embedded with ultra-low content ZnO quantum dots as catalysts for CO2 hydrogenation to methanol

CO2 hydrogenation coupled with renewable energy to produce methanol is of great interest. Carbon coated In2O3 hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO2 hydrogenation to methanol. ZnO-In2O3-II catalyst had the highest CO2 and H2 adsorption capacity, which demonstrated the highest methanol formation rate. When CO2 conversion was 8.9%, methanol selectivity still exceeded 86% at 3.0 MPa and 320 °C, and STY of methanol reached 0.98 gMeOHh−1gcat−1 at 350 °C. The ZnO/In2O3 QDs heterojunctions were formed at the interface between ZnO and In2O3(222). The ZnO/In2O3 heterojunctions, as a key structure to promote the CO2 hydrogenation to methanol, not only enhanced the interaction between ZnO and In2O3 as well as CO2 adsorption capacity, but also accelerated the electron transfer from In3+ to Zn2+. ZnO QDs boosted the dissociation and activation of H2. The carbon layer coated on In2O3 surface played a role of hydrogen spillover medium, and the dissociated H atoms were transferred to the CO2 adsorption sites on the In2O3 surface through the carbon layer, promoting the reaction of H atoms with CO2 more effectively. In addition, the conductivity of carbon enhanced the electron transfer from In3+ to Zn2+. The combination of the ZnO/In2O3 QDs heterojunctions and carbon layer greatly improved the methanol generation activity.

Electrochemical CO2reduction towards formic acid and methanol on transition metal oxide surfaces as a function of CO coverage

Density functional theory is used to study the effect of varying CO coverage on transition metal oxide surfaces on the selectivity and activity of the CO2reduction reaction towards methanol and formic acid formation.

C-Axis-oriented sheet-like Cu/AEI zeolite contributes to continuous direct oxidation of methane to methanol

The cubic and sheet-like AEI zeolites were prepared in the absence and presence of CTAB. Sheet-like Cu/AEI zeolite exhibited more stable and higher methanol formation rate than the cubic-shaped one due to the shortened straight channel length.