Dimethyl Ether Synthesis Research Articles

Kinetics of the direct DME synthesis from CO2 rich syngas under variation of the CZA-to-γ-Al2O3 ratio of a mixed catalyst bed.

The one-step synthesis of dimethyl ether over mechanical mixtures of Cu/ZnO/Al2O3 (CZA) and γ-Al2O3 was studied in a wide range of process conditions. Experiments were performed at an industrially relevant pressure of 50 bar varying the carbon oxide ratio in the feed (CO2 in COx from 20 to 80%), temperature (503–533 K), space-time (240–400 kgcat s mgas−3), and the CZA-to-γ-Al2O3 weight ratio (from 1 to 5). Factors favoring the DME production in the investigated range of conditions are an elevated temperature, a low CO2 content in the feed, and a CZA-to-γ-Al2O3 weight ratio of 2. A lumped kinetic model was parameterized to fit the experimental data, resulting in one of the predictive models with the broadest range of validity in the open literature for the CZA/γ-Al2O3 system.

Sorption enhanced dimethyl ether synthesis under industrially relevant conditions: experimental validation of pressure swing regeneration

High single-pass production of dimethyl ether from CO2-rich feedstock is demonstrated by pressure swing regeneration, allowing enormous increase in productivity.

Enhanced stability of Fe-modified CuO-ZnO-ZrO2-Al2O3/HZSM-5 bifunctional catalysts for dimethyl ether synthesis from CO2 hydrogenation

A series of iron (Fe) modified CuO-ZnO-ZrO2-Al2O3 (CZZA) catalysts, with various Fe loadings, were prepared using a co-precipitation method. A bifunctional catalyst, consisting of Fe-modified CZZA and HZSM-5, was studied for dimethyl ether (DME) synthesis via CO2 hydrogenation. The effects of Fe loading, reaction temperature, reaction pressure, space velocity, and concentrations of precursor for the synthesis of the Fe-modified CZZA catalyst on the catalytic activity of DME synthesis were investigated. Long-term stability tests showed that Fe modification of the CZZA catalyst improved the catalyst stability for DME synthesis via CO2 hydrogenation. The activity loss, in terms of DME yield, was significantly reduced from 4.2% to 1.4% in a 100 h run of reaction, when the Fe loading amount was 0.5 (molar ratio of Fe to Cu). An analysis of hydrogen temperature programmed reduction revealed that the introduction of Fe improved the reducibility of the catalysts, due to assisted adsorption of H2 on iron oxide. The good stability of Fe-modified CZZA catalysts in the DME formation was most likely attributed to oxygen spillover that was introduced by the addition of iron oxide. This could have inhibited the oxidation of the Cu surface and enhanced the thermal stability of copper during long-term reactions.

Carbon dioxide reduction to synthetic fuel on zirconia supported copper-based catalysts and gibbs free energy minimization: Methanol and dimethyl ether synthesis

Thermodynamic equilibria of carbon dioxide recycling via CO2 hydrogenation were predicted by minimization of Gibbs free energy at given conditions, where all existing components were in the gaseous state, for comparison with experimental results obtained with zirconia supported copper-based catalysts. Carbon dioxide hydrogenated to synthetic fuel, i.e. methanol, was investigated at 10 bar and 150–400 °C. The CuZnZrO2 catalyst was highly selective towards methanol at low temperatures (up to 99% selectivity), offering the highest yield of 12.6 g CH3OH kg-catalyst−1 h−1. However, carbon monoxide was the product with higher selectivity at temperatures above > 210 °C. Physically mixing CuZnZrO2 with potassium-modified HZSM5 zeolite increased the CO2 conversion. The synergetic effect between potassium-modified HZSM5 zeolite improved the production of methanol which can be subsequently transformed into dimethyl ether. The bi-functional catalyst allowed the synthesis of valuable products at 50.3 g kg-catalyst−1 h−1 (CH3OH, dimethyl ether, and hydrocarbon), while mixing pure HZSM5 with CuZnZrO2 was inherently selective towards hydrocarbons (up to 80%) and allowed the synthesis of valuable products at 14.6 g kg-catalyst−1 h−1.

The Techno-Economic Benefit of Sorption Enhancement: Evaluation of Sorption-Enhanced Dimethyl Ether Synthesis for CO2 Utilization

Dimethyl ether (DME) is an important platform chemical and fuel that can be synthesized from CO2 and H2 directly. In particular, sorption-enhanced DME synthesis (SEDMES) is a novel process that uses the in situ removal of H2O with an adsorbent to ensure high conversion efficiency in a single unit operation. The in situ removal of steam has been shown to enhance catalyst lifetime and boost process efficiency. In addition, the hydrogen may be supplied through water electrolysis using renewable energy, making it a promising example of the (indirect) power-to-X technology. Recently, major advances have been made in SEDMES, both experimentally and in terms of modeling and cycle design. The current work presents a techno-economic evaluation of SEDMES using H2 produced by a PEM electrolyzer. A conceptual process design has been made for the conversion of CO2 and green H2 to DME, including the purification section to meet ISO fuel standards. By means of a previously developed dynamic cycle model for the SEDMES reactors, a DME yield per pass of 72.4 % and a carbon selectivity of 84.7% were achieved for the studied process design after optimization of the recycle streams. The production costs for DME by the power-to-X technology SEDMES process at 23 kt/year scale are determined at ∼€1.3 per kg. These costs are higher than the current market price but lower than the cost of conventional DME synthesis from CO2. Factors with the highest impact on the business cases are the electricity and CO2 cost price as well as the CAPEX of the electrolyzer, which is considered an important component for technology development. Furthermore, as the H2 cost constitutes the largest part of the DME production cost, SEDMES is demonstrated to be a powerful technology for efficient conversion of green H2 into DME.

Numerical modelling of sorption-enhanced gasification: Development of a fuel decomposition model

Sorption-enhanced gasification (SEG) is a promising technology for producing renewable feedstock gas to be used in biofuel synthesis processes, especially in dimethyl ether (DME) synthesis. To adopt the technology on a commercial scale, it is necessary to acquire knowledge about the related operational characteristics. The SEG process is carried out at lower temperatures than those employed in conventional gasifiers. A typical operating range is from 600 °C to 800 °C. Fuel decomposition experiments have shown distribution of the decomposition products to vary by the process temperature in this operating range, and thus, it is important to adapt this phenomenon for modelling the SEG process. To model the temperature dependence of the decomposition products, a fuel model was developed. Fuel decomposition experiments were conducted to obtain the boundary conditions for the fuel model. The developed fuel model was implemented to an SEG model frame, and the model prediction was compared against data from a 200 kWth dual fluidised bed facility. The model gave satisfactory predictions for producer composition and temperature trends. Furthermore, the main balances of the model were in agreement with typical trends of the SEG process. The conducted simulations improved our understanding of material balances in SEG reactors. Knowledge from physical operations governing the process is of value in further development of the technology.

Synergy of Lewis and Brønsted acid sites for polyoxymethylene dimethyl ether synthesis from methanol and formaldehyde solution over Zr4+ modified sulfonated resin

Polyoxymethylene dimethyl ether (PODEn) is a clean, effective and promising diesel additive. In this work, acidic sulfonated resin modified by zirconium (Zr4+-SR), which possess both Lewis and Brønsted acid sites, was employed to catalyze the synthesis of PODEn from methanol (MeOH) and formaldehyde (FA) solution. The catalysts were investigated by various characterization methods including SEM, BET, XPS, FT-IR, NH3-TPD, Pyridine FT-IR, TG-MS and ICP-OES. It was found that the introduction of Zr4+ into cationic exchange resin formed the Lewis acid sites and improvement of the catalytic performance in PODEn synthesis from methanol and formaldehyde solution was attributed to the synergistic effect of Lewis and Brønsted acid sites. With the increase of zirconium loading, the amount of Lewis acid sites and weak acidity of the Zr4+-SR catalyst increased gradually, and the catalytic activity of the catalysts for the PODEn synthesis reaction exhibited a trend of increasing first and then decreasing. In the methanol and formaldehyde solution, Brønsted acid sites were active for the acetalization of hemiformal and methanol, while Lewis acid sites were conducive to the activation of the methylene glycol. A possible reaction route for the PODEn synthesis from methanol and formaldehyde solution was proposed. 61.1% methanol conversion, 98.7% PODE1–6 and 22.4% PODE3–6 selectivity were achieved under optimal reaction conditions. The reusability investigation of the Zr4+-SR catalyst showed a stable catalytic activity for the synthesis of PODEn from methanol and formaldehyde solution and revealed that the decrease of catalyst activity was attributed to the partial loss of the zirconium.

The Effect of Zeolite Features on the Dehydration Reaction of Methanol to Dimethyl Ether: Catalytic Behaviour and Kinetics.

The synthesis of dimethyl ether (DME) is an important step in the production of chemical intermediate because it is possible to prepare it by direct hydrogenation of CO2. This paper reports the effect of different zeolitic frameworks (such as: BEA, EUO, FER, MFI, MOR, MTW, TON) on methanol conversion, DME selectivity and catalyst deactivation. The effect of crystal size, Si/Al ratio and acidity of the investigated catalysts have been also studied. Finally, the kinetic parameters (such as: ∆H, ∆S and ∆G) have been evaluated together with pre-exponential factor and activation energy for catalysts with FER and MFI structure topology.

The catalytic activity of Co/kaolinite catalyst for dimethyl ether synthesis via methanol dehydration

The production of dimethyl ether (DME), renewable fuel, using dehydration of methanol over Co supported on kaolinite catalysts was investigated. In this study, kaolinite was modified by impregnation of the various percentage of Co (5%Co/KN, 10%Co/KN, and 15%Co/KN) to improve the activity of the catalyst. The prepared catalysts were characterized by nitrogen gas adsorption using the Brunauer–Emmett–Teller (BET) method, and the X-ray diffractometer (XRD). The thermogravimetric analysis (TGA) was used to analyze of coke formation on spent catalysts. The catalytic performances of catalysts were tested in a fixed-bed reactor at atmospheric pressure at the temperature range of 250–350 °C with a fixed weight hourly space velocity (WHSV) of 2.054 h−1. It was found that 5%Co/kaolinite showed the highest methanol conversion of 81.7% among the Co/KN catalysts; however, the DME selectivity was less than 80%. The presence of Co gave the less formation of coke on used catalysts indicating that the Co/KN catalyst had more stable than unmodified kaolinite. The 15%Co/KN is an active, selective, and durable catalyst for DME production at the temperature of 300 °C.

Effect of acidic MCM-41 mesoporous silica functionalized with sulfonic acid groups catalyst in conversion of methanol to dimethyl ether

The global issue of contamination and power reserves has given dimethyl ether (DME) considerable attention. It is an encouraging and clean green material for the future resulting from its clean combustion properties. In this paper, a novel MCM-41-propyl-SO3H catalyst was successfully prepared with tethering of the active sulfonic acid groups onto the support via covalent bonds. This material was investigated as catalyst for DME synthesis via methanol dehydration in a fixed bed flow reactor at different experimental settings. TGA, NH3-TPD, SEM, XRD and BET techniques​ were utilized to characterize the synthesized material. MCM-41 sulfonated catalyst showed great thermal stability, high surface area and significant acid loading. The catalytic tests also demonstrated that the maximum methanol conversion was observed at 350 °C and catalyst contact time of 8 s. In addition, the catalyst showed a total selectivity to DME; light hydrocarbons and higher oxygenated compounds were not formed at temperatures above 300° C.

Production of Dimethyl Ether from Nitrogen-Containing Syngas

A series of experiments in conversion of nitrogen-rich (above 40 vol %) syngas to produce dimethyl ether (DME) was carried out in a flow-through pilot installation. Two commercial catalysts, specifically a DV-8-2 methanol catalyst and a γ-Al2O3 dehydration catalyst, were used as components of a bifunctional catalyst. The paper introduces the concept of reacting gas, the content of which in syngas corresponds to the sum of the content of hydrogen and carbon oxides. No methanol or DME was detected in the converted gas leaving the reactor, as these compounds condense in a water-cooled separator. The following performance values were achieved after more than 600 total running hours of the bifunctional catalyst: DME selectivity at least 66% and DME productivity up to 340 L kgcat–1 h–1. The study of single-stage DME synthesis from nitrogen-containing syngas has demonstrated the practicability for an industrial process technology using commercial components in a bifunctional catalyst.

Study of catalyst bed composition for the direct synthesis of dimethyl ether from CO2-rich syngas

In this work, we study the direct synthesis of DME using CO2-rich syngas, with a CO2/CO ratio similar to that obtained from the gasification of biomass, i.e., 1.9. We used catalytic beds consisting of physical mixtures of the benchmark catalysts used for the synthesis of methanol from syngas and for methanol dehydration to DME, namely Cu/ZnO/Al2O3 and γ-Al2O3, respectively. Our results show that the ratio between each catalytic phase determines the productivity and selectivity to DME, as well CO and CO2 conversions. Thus, higher total carbon conversions were obtained with the catalytic bed with the highest content of the Cu/Zn/Al2O3 phase. The presence of γ-Al2O3 allows to exceed the equilibrium conversion of CO for the syngas to methanol synthesis. The highest DME productivity is obtained with the catalytic bed containing equal amounts of both catalytic phases. In addition, we also show that other reaction variables such as temperature, pressure, and contact time also play an important role in terms of DME productivity. The presence of a high fraction of CO2 in the syngas results in a high production of H2O, which after long times on stream result in the deactivation of the Cu/ZnO/Al2O3 catalytic phase due to the sintering of the copper particles. The in situ removal of H2O via the addition of an H2O sorbent, zeolite 3A, into the catalytic bed, results in a significant enhancement of both carbon conversion and DME productivity.

Model validation of a packed bed LTA membrane reactor for the direct synthesis of DME from CO/CO2

A model for simulating the direct synthesis of dimethyl ether (DME) in a packed bed membrane reactor (PBMR) has been validated, using a LTA zeolite hydrophilic membrane in a lab-scale reaction equipment. In the model, membrane permeability data and the kinetic model corresponding to a CuO-ZnO-ZrO2/SAPO-11 catalyst have been used. Experimental runs have been carried out under the following conditions: 275–325 °C; 20–40 bar; space time, 10 g h (molC)−1; CO2/COx ratio, 0, 0.5 and 1; H2/COx ratio, 3. The model is suitable for predicting the molar fractions of the compounds of the reaction medium (H2, CO, CO2, H2O, DME, methanol and hydrocarbons) in the reaction and permeate sections of the PBMR, and their evolution with time on stream. DME yield, CO and CO2 conversions are greater in the PBMR than without using the membrane, due to the displacement of the thermodynamic equilibrium by the partial separation of H2O from the reaction medium. For H2 + CO feeds, the maximum DME yield is 68% at 325 °C and 40 bar with a space time value of 10 g h (molC)−1. Otherwise, feeding H2 + CO2, CO2 conversion reaches 17%, with a DME yield over 5%.

Controllable synthesis of polyoxymethylene dimethyl ethers by ionic liquids encapsulated in mesoporous SBA-16

Abstract The promising combustion and emission properties of polyoxymethylene dimethyl ethers (PODEn) are of significant interest. However, the synthesis of PODEn products with desired chain lengths is still a problem facing synthetic PODEn. Herein, a series of unique IL@SBA-16-Cx solid catalysts are prepared by encapsulation of ionic liquids (ILs) within the nanocage of SBA-16 through a silylation method. The structure of the encapsulated catalyst was characterized by UV–vis spectra, Fourier transform infrared (FT-IR), N2 adsorption–desorption isotherms, Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Elemental analysis. The encapsulated catalysts show similar catalytic activity to the homogeneous counterparts and display higher selectivity to the targeted PODE3–5 products than their homogeneous counterparts in the synthesis of PODEn from methanol (MeOH) and trioxymethylene (TOM). The encapsulated catalysts exhibit a superior PODE3–5 selectivity and could be the promising catalysts for PODEn synthetic reaction.

Dimethyl ether as circular hydrogen carrier: Catalytic aspects of hydrogenation/dehydrogenation steps

DME may be considered a promising circular hydrogen carrier, as it can be produced also from CO 2 . Catalytic aspects of both hydrogenation/dehydrogenation steps are deeply discussed for pushing advances in this field. The intermittent nature of renewable resources requires for most applications the development of efficient and cost-effective technologies for steady supply of electrical energy. The storage of energy in the form of hydrogen chemically bound within organic molecules (rather than physically as compressed gas or cooled liquid) represents an alternative approach that is attracting great research interest. Compared to other liquid organic hydrogen carriers (LOHCs), dimethyl ether (DME) appears to have the largest potential impact on society, especially if inserted in technological chains of CO 2 sequestration and utilization, so to determine an effective mitigation of environmental issues, without any net effect on the carbon footprint. Specifically, the steps of H 2 storage and H 2 release can take place in two coupled chemical processes, constituted by the exothermic synthesis of DME via CO 2 hydrogenation and the endothermic steam reforming of DME, respectively. Herein, the latest advances in the development of heterogeneous bifunctional and hybrid catalysts for the direct hydrogenation of CO 2 to DME are thoroughly reviewed, with special emphasis on thermodynamics, catalyst design and process feasibility. Despite many aspects behind the mechanism of DME synthesis from H 2 -CO 2 streams are still to be uncovered, the recent progress in the research on H 2 release by DME steam reforming is increasing the interest for effectively closing this binary H 2 loop, in view of future green deals and sustainable research developments.

Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. We studied the effect of the HPW loading on TiO2 (from 1.4 to 2.7 monolayers) on the dispersion and acid characteristics of the HPW clusters. When the concentration of the heteropoliacid is slightly higher than the monolayer (1.4 monolayers) the acidity of the clusters is perturbed by the surface of titania, while for concentration higher than 1.7 monolayers results in the formation of three-dimensional HPW nanocrystals with acidity similar to the bulk heteropolyacid. Physical hybridization of supported heteropolyacids with the Cu-ZnO(Al) catalyst modifies both the acid characteristics of the supported heteropolyacids and the copper surface area of the Cu-ZnO(Al) catalyst. Hybridization gives rise to a decrease in the copper surface area and the disappearance of the strong acidic sites typical of HPW nanocrystals, showing all hybrids similar acid sites of weak or medium strength. The activity of the hybrids was tested for direct DME synthesis from syngas at 30 bar and 250 °C; only the hybrids with HPW loading higher than 1.4 monolayers showed activity for the direct synthesis of DME, showing that the sample loaded with 2.7 monolayers of heteropolyacid had higher activity than the reference hybrid representative of the most widely applied catalysts based on the combination of Cu-ZnO(Al) with HZSM-5. In spite of the high activity of the hybrids, they show a moderate loss in the DME production with TOS that denotes some kind of deactivation of the acidity function under reaction conditions.

Staging of di-methyl-ether (DME) synthesis reactor from synthesis gas (syngas): Direct versus indirect route

Di-methyl-ether (DME) has been received much attention because of its key features. It can be produced from any carbon-rich feedstock through the conversion of carbonaceous material to synthesis gas (syngas) and then to DME via indirect or direct route.In the current paper, the DME reactor is modeled and the effect of reactor staging on the reactor productivity and a measure of annual profit is investigated. Different number of stages, inlet syngas composition, and direct/indirect DME synthesis routes from syngas was considered.For the direct DME synthesis with an inlet syngas H2/(CO+CO2) of 2.33 and maximization of DME production as the objective function, staging of a DME reactor (with total volume of 100m3) to two and three stages increases the reactor productivity by 23.4% and 26.9%, respectively. In each case, the volumes of stages are included in the optimization. If the volumes of stages set to be equal (2×50m3 or 3×33.33m3), the reactor productivity of the two- and three-stage systems becomes 17.3% and 22.5% higher than the single-stage reactor. When the inlet H2/(CO+CO2) is set to 1, sectioning the DME reactor to stages increases the reactor productivity as well.For the indirect DME production route, the optimization results indicate that the DME production rates of the two- and three-stage cases are lower than the direct route.The profitability index of the two- and three-stage reactor systems is 65.53% and 72.35% higher than the single-stage reactor. This is because of higher DME production and lower heat transfer area requirement of the staged configurations.

Efficient in-situ water adsorption for direct DME synthesis: Robust computational modeling and multi-objective optimization

The concept of in-situ water elimination in the novel integrated multifunctional reactor (MR) with the aim of increasing Dimethyl Ether (DME) production via direct method synthesis is investigated in the present study. Introducing continuous regenerative 4 A zeolite adsorbent in the moving bed reactor with syngas feed stream is considered an impressive improvement over the conventional fixed sorption enhanced reactor. In the absence of water adsorption, the validation results exhibit that the offered comprehensive 1-D heterogeneous model equipped with Unilan isotherm has an excellent agreement with industrial data. Also, the simulation results illustrate that around 35% and 25% elevation in the DME production rate and selectivity is obtained via effective water removal in the MR compared to the non-adsorbent configuration. Enjoying in-situ water removal in the MR, synthesis gas conversion plus methanol production is significantly improved. The multi-objective optimization of MR recruiting powerful NSGA-II algorithm with the purpose of maximizing DME production rate and selectivity is accomplished. Among the three distinct decision-making approaches, Shannon's Entropy presents better results according to the deviation index parameter. Operating at optimal conditions in the MR enhance around 201 ton/day and 31% in the DME production and selectivity, respectively, rather than the conventional reactor. Moreover, curbing CO2 emission nearby 122 ton/day leads to consider the MR as an environmentally friendly reactor.

Ionic Liquid Encapsulated in MIL-100(Fe): A Green Catalyst for Synthesis of Polyoxymethylene Dimethyl Ethers from Methanol and Trioxane

Polyoxymethylene dimethyl ether (PODEn) is a promising ether fuel. Especially PODE3–5 can be directly mixed into diesel without modification of the diesel engine’s infrastructure for improving thermal efficiency, and significant reduction in particulate matter (PM) and nitrogen oxides (NOx) emissions. In this paper, a series of heterogeneous catalysts, the imidazole sulfonate ionic liquids (ILs) encapsulated in the cages of metal–organic frameworks (MOFs) MIL-100(Fe), were used successfully and efficiently in the synthesis of polyoxymethylene dimethyl ethers (PODEn) from methanol and trioxane (TOX). These catalysts have exhibited excellent catalytic properties because of strong Brønsted acid sites. MIL-100(Fe)@[BSO3HIm][CF3SO3] shows the best catalytic activity with 96.98% conversation of TOX and 47.49% selectivity of the desired product PODE3–5 under a mild reaction condition. Of importance is that the catalyst is recovered easily and reused.

Evaluation of n-butene synthesis from dimethyl ether in the production of 1,3-butadiene from lignin: A techno-economic analysis

1,3-BD production process from lignin consisting of four unit operations such as gasification, dimethyl ether (DME) synthesis, n-butene synthesis, and isomerization/dehydrogenation, was simulated. This process could be designed as a renewable energy system that can not only produce 1,3-BD but also self-supply almost all the heat and power for the operation. The balance of payment (BP), which is the income incurred from processing a unit weight of lignin, was employed as the economic efficiency of the process. The effect of the reaction conditions in the DME to n-butene synthesis step (the third step) on the BP was investigated. Since few catalysts have been reported for synthesizing n-butene from DME, realistic reaction conditions and catalytic performance were set. An increase in the DME content of the feed gas and a decrease in the reaction pressure led to an increase in the n-butene yield and a decrease in the power, followed by an increase in the 1,3-BD yield and BP. Considering the expected power selling price after the termination of the Feed-in-Tariff scheme, the 1,3-BD production process could have comparable BPs with gasification power generation as a representative competitive process.