Dimethyl Ether Synthesis Research Articles

Cu/ZnO Catalysts: Cu/ZnO Catalysts Derived from Bimetallic Metal–Organic Framework for Dimethyl Ether Synthesis from Syngas with Enhanced Selectivity and Stability (Small 14/2020)

Cu/ZnO Catalysts: Cu/ZnO Catalysts Derived from Bimetallic Metal–Organic Framework for Dimethyl Ether Synthesis from Syngas with Enhanced Selectivity and Stability (Small 14/2020)

Bifunctional Silicotungstic Acid and Tungstophosphoric Acid Impregnated Cu–Zn–Al & Cu–Zn–Zr Catalysts for Dimethyl Ether Synthesis from Syngas

In the present study, a set of methanol synthesis catalysts with different Cu/Zn/Al or Cu/Zn/Zr molar ratios were synthesized by a co-precipitation method. Silicotungstic acid and tungstophosphoric acid were impregnated into these materials to synthesize new bifunctional catalytic materials to be used in direct synthesis of dimethyl ether (DME) from syngas. In the case of methanol production, synthesized Cu/Zn/Al catalysts exhibited quite high methanol selectivity, reaching to approximately 87%. These results indicated that the dispersion of copper particles profoundly affected the selectivity of methanol. Direct synthesis of DME was investigated in the presence of heteropoly acid impregnated copper-based novel hybrid type bifunctional catalysts. Results revealed that product distributions were strongly influenced by the reaction temperature, pressure, heteropoly acid content, and type. Results proved that silicotungstic acid (STA) impregnated bifunctional catalysts showed much better catalytic performance than the tungstophosphoric acid (TPA) impregnated ones in DME synthesis from syngas. Very high dimethyl ether selectivity values were achieved in direct synthesis of dimethyl ether over the 25%, and 30% STA impregnated methanol synthesis catalysts, at 275 °C and 50 bar. DME selectivity presented an increasing trend due to the increase in heteropoly acid content over methanol synthesis catalysts. The silicotungstic acid incorporated (30%) Cu/Zn/Al catalyst, having a composition of 6/3/1 (30STA@CZA:631), showed the highest CO conversion and DME selectivity. However, coke formation over this catalyst was much more than the catalyst containing 25% STA. This is mainly due to the higher Bronsted acidity of 30STA@CZA:631 than 25STA@CZA:631. Low coke formation, together with quite high DME selectivity values achieved with 25STA@CZA:631, is a worthy distinction of this catalyst for the direct synthesis of DME from synthesis gas. Novel hybrid type catalysts are successfully synthesized for direct synthesis of dimethyl ether process. Heteropoly acid incorporated methanol synthesis catalysts are very active and stable in the direct synthesis of dimethyl ether process. Silicotungstic acid (STA) impregnated copper-based catalyst exhibits a superior performance than the tungstophosphoric acid impregnated catalyst.

Cu/ZnO Catalysts Derived from Bimetallic Metal-Organic Framework for Dimethyl Ether Synthesis from Syngas with Enhanced Selectivity and Stability.

Direct conversion of syngas to dimethyl ether (DME) through the intermediate of methanol allows more efficient DME production in a simpler reactor design relative to the conventional indirect route. Although Cu/ZnO-based multicomponent catalysts are highly active for methanol synthesis in this process, the sintering issue of Cu during the prolonged reaction generally deteriorates their performance. In this work, Cu/ZnO catalysts in a novel octahedron structure are prepared by a two-step pyrolysis of Zn-doped Cu-BTC metal-organic framework (MOF) in N2 and air. The catalyst CZ-350/A, hybrid of MOF-derived Cu/ZnO sample CZ-350 and γ-Al2 O3 for methanol dehydration, displays the best activity for DME formation (7.74% CO conversion and 70.05% DME selectivity) with the lowest deterioration rate over 40 h continuous reaction. Such performance is superior to its counterpart CZ-CP/A made via the conventional coprecipitation method. This is mainly due to the confinement of Cu nanoparticles within the octahedron matrix hindering their migration and aggregation. Besides, partial reduction of ZnO in the activated CZ-350 prompts the formation of Cu+ -O-Zn, further facilitating the DME production with the highest selectivity compared to literature results. The results clearly indicate that Cu and ZnO distribution in the catalyst architecture plays an important role in DME formation.

CO2 Utilization Process Simulation for Enhancing Production of Dimethyl Ether (DME)

Increase in the world energy demand also increases the concentration of CO2 in the atmosphere, which contributes to global warming and ocean acidification. This study proposed the simulation process to utilize CO2 released from the acid gas removal unit in one of gas processing plants in Indonesia to enhance the production of dimethyl ether (DME) through unreacted gas recycle that can be beneficial in reducing CO2 emission to the atmosphere. Simulation was developed in Unisim R390.1 using Peng–Robinson–Stryjek–Vera (PRSV) as a fluid package. Simulation was validated by several studies conducted by many researchers and giving satisfactory results especially in terms of productivity, conversion, and selectivity as a function of reactor temperatures in the indirect and the direct DME synthesis processes. Simulation results show that the DME production was enhanced by around 49.6% and 65.1% for indirect and direct processes, respectively, at a recycling rate of 7 MMSCFD. Compressor is required to increase the unreacted gas pressure to the desired pressure in the methanol reactor or dual methanol-DME reactor in both processes. Specific power consumption (SPC) was used as a tested parameter for the effectiveness of recycling unreacted gas. Based on the simulation, the direct DME synthesis process is superior over the indirect process in terms of DME and methanol productions, SPCs, and system energy efficiencies.

Mechanism and catalytic performance for direct dimethyl ether synthesis by CO2 hydrogenation over CuZnZr/ferrierite hybrid catalyst

Direct synthesis of dimethyl ether (DME) by CO2 hydrogenation has been investigated over three hybrid catalysts prepared by different methods: co-precipitation, sol-gel, and solid grinding to produce mixed Cu, ZnO, ZrO2 catalysts that were physically mixed with a commercial ferrierite (FER) zeolite. The catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of CO2 (CO2-TPD), temperature programmed desorption of NH3 (NH3-TPD), and temperature programmed H2 reduction (H2-TPR). The results demonstrate that smaller CuO and Cu crystallite sizes resulting in better dispersion of the active phases, higher surface area, and lower reduction temperature are all favorable for catalytic activity. The reaction mechanism has been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Methanol appears to be formed via the bidentate-formate (b-HCOO) species undergoing stepwise hydrogenation, while DME formation occurs from methanol dehydration and reaction of two surface methoxy groups.

Synthesis of oxymethylene dimethyl ethers (OMEn) via methanol mediated COx hydrogenation over Ru/BEA catalysts

Oxymethylene dimethyl ethers (OMEn) are attracting a lot of research interest but application in chemical industry is not yet practical due to a number of challenges. In this work, OMEn production is reported from methanol mediated heterogeneous catalytic COx hydrogenation over Ru catalysts. Highest yield was achieved over 3%Ru/BEA at 150 °C, 75 barg and H2/CO2 molar ratio of 3. Molecular sieve water adsorbent was used during CO2 hydrogenation to remove water, which increased the selectivity towards OMEn. An investigation of reaction mechanism showed the dominancy of formaldehyde intermediate route over methyl formate route for 3%Ru/BEA catalyst. In present study, CO2 hydrogenation provided the maximum OME1 and OME2 yields of 7.42 and 2.13 mmol/gcat.LMeOH, respectively at the above conditions.

Process Analysis of Chemical Looping Systems for Dimethyl Ether Synthesis from Coal

Coal is an essential primary energy source in modern industry. An important pathway of coal utilization is to gasify coal into syngas, which is then used for downstream production of numerous chemicals such as methanol and liquid fuels. Despite its wide applications, conventional coal gasification still faces challenges such as the use of a costly air separation unit and limited syngas H2/CO ratio. Chemical looping gasification technology is a promising alternative to replace conventional coal gasification with increased thermal efficiency and higher level of process intensification. This study presents the process analysis of chemical looping coal gasification and its integration with downstream production of dimethyl ether (DME) to reveal the advantages of the chemical looping scheme compared to conventional gasification schemes. This study discusses the simulation strategies to maintain adiabatic operation in the chemical looping system. The operating parameters of the chemical looping system are adjusted to achieve the maximum cold gas efficiency in one case study, while the operating parameters of the chemical looping system are adjusted to achieve the maximum effective thermal efficiency in another case study. These two chemical looping cases involve the integration of the chemical looping system with the DME synthesis in a process that considers overall process material and heat flows and power consumption and generation. An exergy analysis is also conducted for these two integrated chemical looping cases, revealing that they both can achieve around 10% increase in exergy efficiency over the conventional gasification system.

Simulation of single-step dimethyl ether synthesis from syngas

Dimethyl ether (DME) is an alternative energy that simplest ether. DME has 2 ways to synthesis from syngas. The single-step DME synthesis combined methanol synthesis and methanol dehydration in one reactor. This study is focusing on DME production from synthesis gas by used catalyst as CuO–ZnO–Al2O3/γ-Al2O3. For the simulation we simulated in Aspen Plus V8.8 and used Langmuir–Hinshelwood Hougen–Watson (LHHW) kinetic model for the reaction rate of DME synthesis in a plug flow reactor with catalyst. Simulation is varying the temperature range between 220 °C to 300 °C and pressure between 20 bar to 80 bar to find the suitable condition for the single-step DME synthesis with CuO–ZnO–Al2O3/γ-Al2O3 catalyst.

Direct Synthesis of Dimethyl Ether from Syngas Over Hybrid Catalyst with Hierarchical ZSM-5 as the Methanol Dehydration Catalyst

Commercial ZSM-5 zeolites were submitted to alkaline treatment in order to prepare hierarchical ZSM-5 zeolites with hierarchical porosity and moderate acidity. Hybrid bifunctional catalyst comprising a CuO-ZnO-Al₂O₃ (CZA) and zeolite was prepared by physical mixing method, used for the direct synthesis of dimethyl ether (DME) from syngas. The correlation between the textural and acid properties of the zeolite and the catalytic performance of hybrid catalyst has been assessed from the combined results of N₂ physisorption, FTIR of adsorbed pyridine, elemental analysis ICP, online-GC and other characterization techniques. The results indicate that the hybrid catalyst with hierarchical ZSM-5 zeolite exhibits higher activity and stability than that with parent ZSM-5 zeolite due to the synergy effect of moderated acidity and enhanced mass transport capability of the hierarchical ZSM-5 sample. Under 260 °C, 2.0 MPa and 3600 h-1, the conversion of CO and the DME selectivity to DME over hybrid catalyst CZA-ZSM-5(25)-A achieved 65.2% and 67.8%, respectively.

Synthesis of Dimethyl Ether via CO2 Hydrogenation: Effect of the Drying Technique of Alumina on Properties and Performance of Alumina-Supported Copper Catalysts.

Thermal treatment during catalyst preparation is one of the important factors affecting the characteristics and performance of a catalyst. To improve the catalytic performance of an alumina-supported copper catalyst prepared by an impregnation method for dimethyl ether (DME) synthesis from CO2, the effects of the use of hot air and infrared drying as well as calcination at 600 and 900 °C to prepare alumina supports were investigated. Infrared drying could shorten the required drying time by 75% when compared with hot air drying. Infrared drying could also help maintain the pore size and pore volume of the supports, leading to their larger surface areas. Different drying techniques were additionally noted to result in different sizes and shapes of the pores as well as to different copper distributions and intensities of acid sites of the catalyst. An increase in the calcination temperature resulted in a decrease in the surface area of the supports because of particle aggregation. The drying technique exhibited a more significant effect than calcination temperature on the space-time yield of DME. A catalyst utilizing the support prepared by infrared drying and then calcined at 600 °C exhibited the highest yield of DME (40.9 gDME kgcat–1 h–1) at a reaction temperature of 300 °C. Stability of the optimal catalyst, when monitored over a 24 h period, was noted to be excellent.

Dimethyl Ether Production from Sugarcane Vinasse: Modeling and Simulation for a Techno-economic Assessment

Industrialization and energy demand increase are highlighted as consequences of world population growth for decades. Thereby, aiming to contribute to sustainable processes capable of mitigating the effects resulting from this process, biofuels have been intensively researched, produced and used in recent years. Among the possibilities, dimethyl ether (DME) stands out with great prospects replacing liquefied petroleum gas and diesel due to its potential as clean fuel. This work aims to conjoin the production of DME, a biofuel with great prospects for technical performance, safety, and economy, with a favorable destination for vinasse, the most worrying residue of ethanol production, due to its high polluting potential and large production volume in several countries. A rigorous and robust simulation of direct synthesis of DME from vinasse-derived syngas is performed using Aspen Hysys and its supplements, evaluating the technical and economic aspects of its production in ethanol distilleries. Results of the proposed scenario point that the process is technically feasible, reaching a purity of 99.9%, respecting the minimum required by standard norms. In addition, the designed process achieved yields of 1 kg of DME for each 1.6 kg of syngas. The simulated process presented a total capital cost of 47.1 millions of dollars, operating costs of 14.1 millions of dollars per year, and utilities cost of 11.2 millions of dollars per year. Considering energy cogeneration, an economy of 9.2% was reached, resulting in a production cost of simulated stage of 98.36 US$/tonne of DME and, considering a complete scenario, an accumulated cost of 233.48 US$/tonne of DME. It demonstrates an economic competitiveness for the DME price and ensures a considerable profit margin for the process. Consequently, the investigated DME production scenario emerges as a promising diesel substitute in a realistic scenario.

Ethanol as a Binder to Fabricate a Highly‐Efficient Capsule‐Structured CuO−ZnO−Al2O3@HZSM‐5 Catalyst for Direct Production of Dimethyl Ether from Syngas

AbstractThis work reports a highly efficient capsule‐structured CuO−ZnO−Al2O3@HZSM‐5 (CZA@HZSM‐5‐EtOH) core‐shell catalyst for the direct conversion of syngas to dimethyl ether by a facile physical coating method with ethanol as a binder through coating micrometer‐sized HZSM‐5 shell on the prior‐shaped millimeter‐sized CZA core, it shows 2.9 times higher CO conversion with the 2.7 times higher turnover frequency and 9.2 times higher dimethyl ether space‐time yield of the CZA@HZSM‐5‐SS catalyst prepared by a similar process but with silica sol as a binder (315.5 vs 34.3 gDME kgcat−1 h−1). The relationship between the structure and performance was explored by a variety of characterization techniques including X‐ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X‐ray diffraction (XRD), ammonia temperature programmed desorption (NH3‐TPD), nitrogen adsorption‐desorption, H2‐temperature‐programmed reduction (H2‐TPR) and H2‐TPR after oxidation of the samples by N2O. CZA@HZSM‐5‐EtOH can be considered as a highly efficient and practical catalyst for dimethyl ether synthesis from syngas. This work presents a new avenue to design other bifunctional catalysts for the cascade reactions in which the raw materials can be converted into an intermediate over the core and then the as‐formed intermediate over the core can be subsequently converted into the final product.

Citric acid-modified beta zeolite for polyoxymethylene dimethyl ethers synthesis: The textural and acidic properties regulation

Beta zeolite exhibits satisfactory catalytic activity in the synthesis of polyoxymethylene dimethyl ethers. However, the microporous channels of beta zeolite have adverse effects on mass transfer of macromolecules. In this work, it was found that the textural and acidic properties of catalysts could be improved by citric acid treatment. Extensive characterization confirmed that citric acid induced significant pore-expanding on catalysts, and its dealumination and realumination effect could lead to reduced amount of total acid sites and increased amount of Brønsted acid sites (BAS). Meanwhile, a good positive correlation was found between amount of external weak BAS and initial reaction rate. It was speculated that BAS with relatively weak acid strength might be the primary active sites in this reaction. Compared with the blank sample, the initial reaction rate of optimal catalyst was increased by 100 %, and the conversion of trioxane was increased by 86.5 %, indicating a significantly improved catalytic activity.

Implanting Copper−Zinc Nanoparticles into the Matrix of Mesoporous Alumina as a Highly Selective Bifunctional Catalyst for Direct Synthesis of Dimethyl Ether from Syngas

AbstractDimethyl ether (DME) is an industrially important intermediate and clean alternative fuel. Thus, developing an efficient bifunctional catalyst for syngas‐to‐DME is practically important but remains a challenge. In this paper, a copper−zinc implanting into matrix of mesoporous alumina (CuZn@m−Al2O3) catalyst was prepared by introducing the as‐prepared Cu−Zn oxalate nanoparticles into the Al(i‐OPr)3‐containing precursor solution for preparing mesoporous Al2O3 (m‐Al2O3) through evaporation‐inducing assembly method. The preparation of Cu−Zn oxalate in advance for synthesizing CuZn@m−Al2O3 can intensify the Cu−ZnO interaction, confirmed by XRD and H2‐TPR. Thanks to the unique CuZn‐implanting closed structure, CuZn@m−Al2O3 shows 89.0 % of higher selectivity with comparable CO conversion (15.5 %) than the previously reported supported‐type CuZn catalyst on m‐Al2O3 (CuZn/m−Al2O3, 75.2 %) for hydrogenation of syngas to DME. Over the developed CuZn@m−Al2O3 catalyst, 0.16 mmol g−1 cat h−1 of high DME rate can be achieved. CuZn@m−Al2O3 also shows higher methanation resistance (2.7 % CH4) compared to CuZn/m−Al2O3 (6.3 %), ascribed to intensified Cu−Zn interaction owing to the as‐formation of Cu−Zn oxalate in advance. Moreover, Both CuZn@m−Al2O3 and CuZn/m−Al2O3 exhibit high stability. The outstanding catalytic performance of CuZn@m−Al2O3 allows it to be a promising catalyst for DME synthesis from syngas.

Sorption enhanced dimethyl ether synthesis for high efficiency carbon conversion: Modelling and cycle design

Dimethyl ether is one of the most promising alternative fuels under consideration worldwide. Both the conventional indirect DME synthesis and the improved direct DME synthesis process are constrained by thermodynamics, which results in limited product yield, extensive separations and large recycle streams. Sorption enhanced DME synthesis is a novel process for the production of DME. The in situ removal of H2O ensures that the oxygen surplus of the feed no longer ends up in CO2 as is the case for direct DME synthesis. As a result CO2 can be converted directly to DME with high carbon efficiency, rather than being the main byproduct of DME production.The sorption enhanced DME synthesis process is a promising intensification, already achieving over 80 % single-pass CO2 conversion for a non-optimized system. The increased single-pass conversion requires less downstream separation and smaller recycle streams, especially for a CO2-rich feed. A key optimization parameter for the process performance is the adsorption capacity of the system. This capacity can be improved by optimizing the reactive adsorption conditions and the regeneration procedure. In this work, a detailed modelling study is performed to investigate the impact of various process parameters on the operating window and the interaction between different steps in a complete sorption enhanced DME synthesis cycle, and to compare its performance to other direct DME synthesis processes. The development of sorption enhanced DME synthesis, with its high efficiency carbon conversion, could play a significant role in the energy transition in which the carbon conversion will become leading.

Features of Preparation of the Methanol Synthesis Component of a Bifunctional Dimethyl Ether Synthesis Catalyst

The production of dimethyl ether from synthesis gas involves the use of bifunctional catalysts, which mediate the synthesis and dehydration of methanol. The effect is provided by the presence of a methanol synthesis component and a dehydration component in the catalyst; the components can be synthesized independently. The published data on the synthesis of a CuО/ZnО/Al2О3 methanol synthesis catalyst by precipitation from a nitrate solution are conflicting; therefore, it is relevant to study the effect of the procedure and conditions for the precipitation of copper, zinc, and aluminum nitrate solutions with sodium carbonate on the activity of the above catalyst. Data on the phase composition of the precipitates after a heat treatment and the activity of the synthesized catalysts in methanol synthesis suggest that the presence of nitrate groups in the precipitates leads to a decrease in catalytic activity. A method to prepare a methanol synthesis catalyst at room temperature by introducing a solution of copper, zinc, and aluminum salts into a sodium carbonate solution (reverse coprecipitation) is proposed. This method provides the level of activity of the resulting samples directly in methanol synthesis that is close to the level of activity of a commercial methanol synthesis catalyst. Dimethyl ether synthesis in the presence of bifunctional catalysts, in which the methanol synthesis component is prepared by different methods and the dehydration component is commercial gamma-Al2O3, is studied. In the presence of the synthesized samples, the methanol selectivity is almost identical; however, the productivities with respect to oxygenates and dimethyl ether are significantly different.

Synthesis of polyoxymethylene dimethyl ethers over different microporous and mesoporous zeolites: the effects of acidity and pore size

Polymethoxydimethyl ether (PODEn) is an ideal blending component of diesel oil.

Optimization of the direct synthesis of dimethyl ether from CO2 rich synthesis gas: closing the loop between experimental investigations and model-based reactor design

Kinetic modeling, model-based optimization and experimental validation for the direct DME synthesis.

Increasing dimethyl ether production from biomass-derived syngasviasorption enhanced dimethyl ether synthesis

Sorption Enhanced DME Synthesis (SEDMES) is a feasible approach to increase DME production from CO2-rich syngas.

Experimental validation of pressure swing regeneration for faster cycling in sorption enhanced dimethyl ether synthesis.

Sorption enhanced dimethyl ether synthesis (SEDMES) is a novel DME production route from CO2-rich feedstocks. In situ water removal by adsorption results in high single-pass conversions, thereby circumventing the disadvantages of conventional routes, such as low carbon efficiency, energy intensive downstream separation and large recycling. The first-time demonstration of pressure swing regeneration with 80% single-pass carbon selectivity to DME allows for an enormous increase in productivity. Already a factor four increase compared to temperature swing regeneration is achieved, unlocking the potential of SEDMES as a carbon utilisation technology.