Dimethyl Ether Synthesis Research Articles

Strategies for the Intensification of CO2 Valorization in the One-Step Dimethyl Ether Synthesis Process

The intensification of CO2 valorization has been theoretically studied in the direct synthesis of dimethyl ether (DME) carried out in a packed-bed reactor by means of two strategies pursuing the at...

NMR of petrochemical-type chemical reactions

A simple technique is presented for NMR of chemically reacting systems at conditions of high temperature and pressure. The method can follow reactions that are typical of refinery operations – hydrogenation, transfer dehydrogenation, methanol synthesis, and isomerization. All of the reacting materials are flame-sealed into a glass capillary. Gaseous agents such as O2 and CO are loaded into the capillary by condensation at liquid N2 temperature. H2 is provided by loading LiAlH4. The capillary holds the high pressure, up to 7 MPa, so the NMR probe can be a simple design with hot air flowing over the sample tube, up to 350 °C. Example reaction results are presented, including hydrogenation of benzene, hydrogenation/dehydrogenation of cyclohexene to benzene and cyclohexane (a disproportionation), and synthesis of methane, methanol and dimethyl ether from CO and H2. In this work we present a simple, inexpensive method with rapid temperature response for tracking chemical reactions in real-time at high temperature and high pressure.

Intensification of Catalytic Processes through the Pellet Structuring: Steady-State Properties of a Bifunctional Catalyst Pellet Applied to Generic Chemical Reactions and the Direct Synthesis of DME

Structuring of different types of catalytic active centers at a single-pellet level appears to be a promising and powerful tool for integration and intensification of multistep solid-catalyzed chemical reactions. However, the enhancement in the product yield and selectivity strongly depends on the proper choice of the distribution of different catalysts within the pellet. To demonstrate potential benefits from properly designed catalyst pellet, numerical studies were conducted with the aid of the mathematical model of a single spherical bifunctional catalyst pellet. The analysis was performed both for a system of two generic chemical reactions and for a real process, i.e., direct synthesis of dimethyl ether (DME) from synthesis gas via methanol. Evaluation of the pellet performance was done for three arrangements of the catalytic active sites within the pellet, i.e., a uniform distribution of two types of catalytic active centers in the entire volume of the pellet, and two core–shell structures. It was demonstrated that, especially for the larger pellets typical for fixed-bed applications, the product yield might be significantly improved by selecting proper catalyst arrangements within the pellet.

Bifunctional Capsule Catalyst of Al2O3@Cu with Strengthened Dehydration Reaction Field for Direct Synthesis of Dimethyl Ether from Syngas

Direct conversion of syngas to dimethyl ether (DME) using bifunctional catalysts is a promising way to meet the current industrial demands. However, the spatial design of the bifunctional catalyst ...

Enhanced catalytic performance of Zr modified CuO/ZnO/Al2O3 catalyst for methanol and DME synthesis via CO2 hydrogenation

Zirconium (Zr) modified CuO/ZnO/Al2O3 (CZA) catalysts with different aluminum (Al) and Zr contents were synthesized by the co-precipitation method. The synthesized CuO/ZnO/ZrO2/Al2O3 (CZZA) catalysts were comprehensively characterized and studied for methanol synthesis via CO2 hydrogenation. The CZZA catalyst showed the highest methanol yield of 12.4 % at 220 °C and 2.76 MPa with an optimized catalyst composition of Cu/Zn/Zr/Al (atomic ratio) at 4:2:1:0.5. The CZZA catalyst showed better activity than that of the CZA catalyst and a superior stability for methanol synthesis. There was no decrease in the BET surface area and very little coke formation for the spent CZZA catalyst, after 300 h of methanol synthesis. Bifunctional catalysts, composed of CZZA and HZSM-5, were investigated for dimethyl ether (DME) synthesis directly from CO2 hydrogenation, and a maximum DME yield of 18.3 % was obtained at a reaction temperature of 240 °C and a pressure of 2.76 MPa. The stability of the bifunctional CZZA and HZSM-5 catalyst during the DME synthesis also significantly improved, as compared to that of the CZA and HZSM-5. A significant decrease in the BET surface area and an increase in coking on the spent CZZA catalyst were observed after 100 h of DME synthesis, indicating a detrimental effect on CZZA stability when a HZSM-5 catalyst was present. The changes in structural properties (e.g., BET surface area and crystallinity) and coking for HZSM-5 could be responsible for the deactivation of the bifunctional catalyst.

Synthesis of Methanol and Dimethyl Ether from CO2 and H2 Under Flow-Circulation Conditions

In the context of utilization of carbon dioxide emissions, a study of the CO2conversion to methanol and dimethyl ether (DME) under flowcirculation conditions, when a part of converted gas returns to the reactor, was carried out. Experimental data on the synthesis of methanol (commercial catalyst Megamax 507) and direct synthesis of DME (Megamax 507/commercial zeolite ZVM, weight ratio 1/1) are reported. In the methanol synthesis from syngas, vol.%: H2 – 76.6, CO2– 19.8, N2 – 3.6 performed at 240–260 °C and pressure 5.3 MPa, a high conversion of CO2was reached: 84–99.6% at a low selectivity of the side reaction (CO synthesis, not higher than 4.7 %). The maximum specific yield of methanol at 260 °C was 1.24 kg(kgcat·h)–1. Special-purpose experiments demonstrated that the methanol synthesis is accompanied by a small heating (up to 10 °C) at the catalyst bed inlet, which testifies to polytropicity of the reactor. In the synthesis of DME, the DME yield referred to bifunctional catalyst was within 0.16–0.33 kg(kgcat·h)–1depending on the conditions. Therewith, the conversion of methanol to DME was not lower than 42 %, the conversion of CO2was within 79–96 %, and the DME synthesis proceeded under nearly isothermal conditions.

Development of a green process for DME production based on the methane tri-reforming

Abstract The main object of this research is CO2 conversion to dimethyl ether (DME) based on the coupling methane tri-reforming and DME synthesis units and investigation the performance of developed process by a detail mathematical model. In the developed process, CH4 and CO2 as low-cost feedstocks are converted to DME as green and economic energy carrier that has a lower environment, infrastructure, and transportation issues compared to CH4. In the proposed process, the syngas produced through methane tri-reforming feeds to the DME reactor without any rigorous separation. To investigate the efficiency of the developed process, the conversion section of plant is modeled based on the mass and energy balance equations considering heat and mass transfer resistances, while the separation unit is simulated by an equilibrium-based model. In the next step, an optimization problem is formulated to calculate the optimal operating conditions of process to achieve maximum DME production considering process limitations. The simulation results show that considering some quench points on the tri-reformer to distribute the feed stream along the reactor increases DME production capacity from 150.9 to 243.5 ton day−1.

Effect of Pressure and Syngas Composition on Direct Synthesis of Dimethyl Ether using Dual Bed Catalyst

National General Energy Plan of Indonesia 2017 (RUEN 2017) stated that dimethyl ether (DME) is appointed as a blending of LPG to reduce LPG imports. DME can be made with two reaction pathways, namely direct synthesis and indirect synthesis. The objective of this study was to determine the effect of pressure and syngas composition on the direct synthesis of DME using dual fixed bed catalyst. The research was carried out with two types of catalyst: M-xxx as a commercial catalyst for methanol synthesis and γ-Al2O3 as catalyst for dehydration of methanol to DME. The later was prepared in our Laboratory of Chemical Reaction Engineering and Catalysis, ITB. The dual catalyst experiment was carried out at 5 and 7 bars, and a fixed temperature of 240oC. The mass ratio of the M-xxx to γ-Al2O3, so-called M/D ratios, were varied from 1/9 to 9/1. Two type of syngas were used, i.e. SA containing only H2 and CO with a SN of 2,3 and SB containing 4% CO2 with SN of 1,8. The dual bed with a M/D ratio of 1/4 gave a CO conversion up to 62% at 5 bars and 240oC (SA). As pressure increased, the conversion of CO and H2 increases to 85% and 83% at 7 bar and 240oC (SA). The presence of CO2 (SB) decreases catalyst activity, as indicated by the decrease in conversion of CO and H2 to 56% and 54%, at 7 bar and 240oC.

Direct dimethyl ether synthesis over mesoporous Cu–Al2O3 catalyst via CO hydrogenation

Syngas conversion to dimethyl ether (DME) is an important reaction (STD) in C1 chemistry since DME not only possesses high value but also can be used as a vital chemical intermediate. Here, we design a Cu-based mesoporous alumina catalyst to realize the DME synthesis reaction. It exhibits high catalytic activity in terms of CO conversion of 21.2% and DME selectivity of 95.9% according to its synergistic effect between the Cu and alumina. In the Cu-based alumina catalyst, the Cu–Cu bond is for converting CO to methanol and the Cu–Al bond is for the formed methanol dehydration to DME. Therefore, the well-dispersed Cu nanoparticles provide amounts of active sites for methanol synthesizing, at the same time as the strong metal–support interaction between the Cu nanoparticles and mesoporous alumina offering Cu–Al active sites for methanol quick dehydration to DME. In addition, the mesopores supplied by alumina support also accelerate the mass transfer and diffusion, boosting the CO activation. This study points out the real active phase for DME synthesis, which plays an important guiding role in design of related catalysts for DME synthesis. The process of syngas conversion to DME over Cu-based mesoporous alumina catalyst.

Cover Feature: Nature of Synergy between Brønsted and Lewis Acid Sites in Sn–Beta Zeolites for Polyoxymethylene Dimethyl Ethers Synthesis (ChemSusChem 19/2019)

Cover Feature: Nature of Synergy between Brønsted and Lewis Acid Sites in Sn–Beta Zeolites for Polyoxymethylene Dimethyl Ethers Synthesis (ChemSusChem 19/2019)

Supported Intermetallic PdZn Nanoparticles as Bifunctional Catalysts for the Direct Synthesis of Dimethyl Ether from CO‐Rich Synthesis Gas

AbstractThe single‐step syngas‐to‐dimethyl ether (STD) process entails economic and technical advantages over the current industrial two‐step process. Pd/ZnO‐based catalysts have recently emerged as interesting alternatives to currently used Cu/ZnO/Al2O3 catalysts, but the nature of the active site(s), the reaction mechanism, and the role of Pd and ZnO in the solid catalyst are not well established. Now, Zn‐stabilized Pd colloids with a size of 2 nm served as the key building blocks for the methanol active component in bifunctional Pd/ZnO‐γ‐Al2O3 catalysts. The catalysts were characterized by combining high‐pressure operando X‐ray absorption spectroscopy and DFT calculations. The enhanced stability, longevity, and high dimethyl ether selectivity observed makes Pd/ZnO‐γ‐Al2O3 an effective alternative system for the STD process compared to Cu/ZnO/γ‐Al2O3.

Supported Intermetallic PdZn Nanoparticles as Bifunctional Catalysts for the Direct Synthesis of Dimethyl Ether from CO-Rich Synthesis Gas.

The single‐step syngas‐to‐dimethyl ether (STD) process entails economic and technical advantages over the current industrial two‐step process. Pd/ZnO‐based catalysts have recently emerged as interesting alternatives to currently used Cu/ZnO/Al2O3 catalysts, but the nature of the active site(s), the reaction mechanism, and the role of Pd and ZnO in the solid catalyst are not well established. Now, Zn‐stabilized Pd colloids with a size of 2 nm served as the key building blocks for the methanol active component in bifunctional Pd/ZnO‐γ‐Al2O3 catalysts. The catalysts were characterized by combining high‐pressure operando X‐ray absorption spectroscopy and DFT calculations. The enhanced stability, longevity, and high dimethyl ether selectivity observed makes Pd/ZnO‐γ‐Al2O3 an effective alternative system for the STD process compared to Cu/ZnO/γ‐Al2O3.

Exergoeconomic comparison of syngas production from biomass, coal, and natural gas for dimethyl ether synthesis in single-step and two-step processes

Abstract Dimethyl ether (DME) as a promising alternative fuel can be produced through two-step and single-step processes with differently suitable H2/CO ratio in syngas. Natural gas, coal, and biomass are potential energy sources for syngas production to synthesize the DME. In order to analyze the proper process of syngas production for the DME synthesis, this work aims to compare the syngas production processes from biomass gasification, coal gasification, and methane tri-reforming for the sinle-step and two-step processes through the exergoeconomic analysis. The results showed that from the coal gasification achieves the highest energetic efficiencies of the syngas production for both single-step and two-step processes while the methane tri-reforming shows the highest exergetic efficiencies at H2/CO of 2. In the exergoeconomic analysis, the air-steam coal gasification showed the lowest syngas unit cost of 0.65 $/kg for the two-step process, while biomass gasification with air-steam agent presents the lowest unit cost of syngas of 0.54 $/kg for the single-step process. When considering the environmental point of view, the intensity of CO2 emission of biomass gasification with oxygen-steam agent for the single-step process of DME synthesis is the lowest about 2.83 tonne CO2/tonne syngas.

Nature of Synergy between Brønsted and Lewis Acid Sites in Sn-Beta Zeolites for Polyoxymethylene Dimethyl Ethers Synthesis.

The role of Lewis and Brønsted acid sites and their potential synergy remains ambiguous for the production of polyoxymethylene dimethyl ethers (OME), which are suitable as a Diesel substitute. Here, this synergistic effect was investigated by using a series of beta polymorph A (BEA) zeolites with various degrees of Brønsted and Lewis acidity. Lewis acidity was introduced in dealuminated zeolites by Sn grafting in dichloromethane. These sites were only active in paraformaldehyde decomposition, OME growth, and acetalization. The Brønsted acid sites arising from bridging hydroxyl groups were active for all reaction steps, and notably for trioxane ring-opening and dissociation to formaldehyde (FA), which did not occur on the Lewis acid sites. Presence of both Lewis and Brønsted acid sites led to a four-fold increase in turnover frequency and a significant decrease of byproduct formation compared with the parent zeolite during OME synthesis from dimethoxymethane and trioxane. The synergistic effect between both types of acid sites is explained by FA insertion on Lewis acid sites leading to OME growth. Interaction between tetrahedral Sn and the carbonyl group of FA resulted in an activated carbonyl bond, which was likely the initial step for insertion of FA into OME.

BASF, Lutianhua sign MoU for eco-friendly production process for DME

The effects of three different mixing methods of CuO/ZnO/Al2O3 (CZA) and HZSM-5 bifunctional catalyst on the stability for dimethyl ether (DME) synthesis from carbon dioxide (CO2) hydrogenation were investigated. When the bifunctional catalyst was prepared by method A (mixing powder without pelletization), there was no significant change in DME production and catalyst stability when the HZSM-5 loading was varied between 0.1 g and 0.5 g with a fixed CZA loading of 0.5 g,. When the bifunctional catalysts were prepared by method B (pressed into pellets of CZA and pellets of HZSM-5 and then mixed) and method C (mixed CZA and HZSM-5 powders, then pressed into pellets), the mixing methods did not initially impact CO2 conversion and had a minor effect on DME yield. However, long-term tests (100 h) indicated that the mixing method had a significant influence on the catalyst stability. Method B showed the best stability and the extent of catalyst deactivation followed the sequence of method B < method A < method C. Characterizations of spent catalysts indicated that method B could reduce the extent of copper (Cu) oxidation, which due to the relatively low surface contact between Cu active sites and HZSM-5. Large amounts of water generated in CO2 hydrogenation to synthesize DME and intimate contact between CZA and HZSM-5 catalyst could induce severe oxidation of Cu and metal ions migration from hydrogenation catalyst to HZSM-5, which can result in the number reduction of acidic sites.

Chromatographic Procedure for the Determination of Products of the Direct Synthesis of Dimethyl Ether

We developed an original gas chromatographic procedure for determining the products and reagents for the catalytic synthesis of dimethyl ether (DME) from synthesis gas, which enables the simultaneous detection of СН3ОН, DME, СО, СО2, Н2, Н2О, N2, and hydrocarbons to С6. The gas circuit includes four detectors, three packed columns, two precolumns (to prevent water and organic compounds from entering molecular sieve columns) in combination with two relief valves and two pressure regulators for the implementation of the back purging of precolumns. The system is assembled based on a Khromatek-Kristall 5000 chromatograph. The determination is carried out at a constant temperature of 140°C. The duration of analysis is not more than 12 min. Because of the presence of a flame ionization detector, it is possible to detect trace amounts of hydrocarbons, as well as ethane in the presence of large amounts of CO2.

Zr- and La-containing Catalysts in Synthesis of Methanol and Dimethyl Ether

Zirconium oxide samples synthesized and modified with Al, Si, W oxides were studied as dehydrating components of bifunctional catalysts for synthesis of dimethyl ether. ZrO2 modified with Al and Si oxides is inactive in the dehydration of methanol, but its dehydrating activity becomes comparable with the activity of γ-Al2O3 upon introduction of WO3. According to the data on methanol adsorption at 46°C, the adsorption capacity of ZrO2 modified with SiO2 is comparable with the capacity of γ-Al2O3, and that of ZrO2 modified with WO3 is four times lower. The difference in the catalytic and adsorption behavior of the samples is accounted for by the data of in situ high-temperature diffuse reflection IR spectroscopy. A high content of weak Bronsted acid centers is observed on the ZrO2 surface, with the interaction of these with methanol resulting in the methoxylation of the catalyst surface. When W oxide is deposited onto zirconium oxide, the surface has strong Bronsted centers involved in the reaction of methanol dehydration. A coprecipitation from solution of nitrate salts of Cu, Zn, La with Na carbonate, followed by the procedures of filtration, washing, and thermal treatment, yielded a catalyst for synthesis of methanol, the activity of which is close to that of the industrial catalyst.

A novel UiO-66 encapsulated 12-silicotungstic acid catalyst for dimethyl ether synthesis from syngas

Abstract Dimethyl ether (DME) has received great attention as a promising clean fuel and industrially important intermediate. Tremendous efforts have been made to develop highly active and stable catalysts for DME production. Here, we present the first example of the application of metal-organic framework (MOF) catalyst in DME synthesis from syngas. A Zr-MOF (UiO-66) was selected as the catalyst host and support owing to its exceptionally high stability and porosity. UiO-66 was firstly functionalized by silicotungstic acid (H4SiW12O40, STA) via a one-pot synthesis method and then loaded with Cu by a facile solid grinding method. The prepared catalysts were characterized using XRD, TGA, FT-IR, N2 adsorption and TEM. The high porosity and thermal stability of acidified UiO-66 were maintained after 15% wt STA incorporation without any destruction of the Keggin structure of STA. The catalyst was tested for one step DME synthesis from syngas, showing higher DME selectivity and space-time yield than control catalysts. The superior activity of Cu/STA-UiO was attributed to the uniform dispersion of active centres with close intimacy and high density of Bronsted acid sites, as well as strong metal support interaction between Cu and Zr oxide SBU evidenced by XPS analysis.

Structured catalysts for the direct synthesis of dimethyl ether from synthesis gas: A comparison of core@shell versus hybrid catalyst configuration

Abstract The direct synthesis of dimethyl ether (DME) from synthesis gas via methanol as an intermediate is a promising process for realizing a decentralized, small-scale Power-to-X concept. The efficient realization of this coupled process depends to a large extent on the appropriate catalyst configuration, i.e. the combination of the catalyst for methanol formation with the one for the subsequent dehydration step. In this work, two catalyst configurations were compared in terms of CO-conversion and DME-selectivity using modelling and experiments. Catalysts for methanol formation (Cu/ZnO/Al2O3, CZA) and dehydration (Zeolite H-ZSM-5, Z) prepared via flame spray pyrolysis and hydrothermal synthesis, respectively, were combined in the form of hybrid pellets (CZA&Z) and CZA-core@zeolite-shell (CZA@Z) particles. During the synthesis of the CZA@Z system, alteration of the CZA core in terms of CuO-reducibility and activity in methanol synthesis were found after individual steps of calcination and hydrothermal shell synthesis. In contrast, the preparation of the CZA&Z system presents an easy and tunable method with promising catalytic properties in terms of CO-conversion and DME-selectivity, once the proper mass ratio of the two catalysts was set. From modelling, for the same CZA/Z ratio in general higher CO-conversion was found for the CZA&Z system as compared to the CZA@Z, while the latter system shows higher DME-selectivity.

Renewable Energy Based Dimethyl-Ether Production System Linked With Industrial Waste Heat

A new renewable energy based dimethyl-ether (DME) production system is proposed in this paper. The DME is then produced through the indirect synthesis method where methanol is produced first through carbon hydrogenation process, then methanol derived to a process called methanol dehydration to produce the DME. The proposed integrated system consists of four main subsystems named as carbon capturing and heat recovery system, proton exchange membrane (PEM) hydrogen production system, methanol synthesis system, and the DME synthesis system. The main inputs are electrical energy from photovoltaic (PV) solar panels and thermal energy from flue gas waste heat. The system is modeled and simulated using both aspen plus process simulation software and engineering equation solver (EES) and assessed based on energy and exergy approaches. The energy and exergy efficiencies are determined to be 40.46% and 52.81%, respectively.