Steam Reforming Of Dimethyl Ether Research Articles

Enhancement of catalytic activity over Cu-supported montmorillonite catalyst for hydrogen production via steam reforming of dimethyl ether

Enhancement of catalytic activity over Cu-supported montmorillonite catalyst for hydrogen production via steam reforming of dimethyl ether

Assembly of hydrolysis, activation and reforming sites boosting steam reforming of DME over ZnO/TiO2 catalysts

Steam reforming of dimethyl ether (DME SR) through the tandem reactions of DME hydrolysis to methanol and methanol steam reforming (MSR) is a promising process for feeding hydrogen to fuel cells. Herein, we synthesize a series of ZnO/TiO2 catalysts with different Zn contents for DME SR. We discover that TiO2 exhibits excellent methanol activation ability by forming a large amount of methoxy species, and adjacent ZnO sites can directly utilize them for the substantial steam reforming. Compared with TiO2 and ZnO alone, the MSR reaction rate over the 2ZnO/TiO2 catalyst (with a Zn content of 2 wt%) at 340 °C increases by 56 and 38 times, respectively. For DME SR, DME hydrolysis could occur on strong acidic sites of the TiO2 support to generate methanol molecules to subsequently involve in MSR. The synergy as described above significantly enhances the DME SR activity. Additionally, the adsorption strength of the oxygenated intermediates formed on the ZnO/TiO2 catalysts is weaker than that on TiO2, which then inhibits the reactions of methanation and methanol/DME decomposition. The 2ZnO/TiO2 catalyst exhibits low CO (2.8%) and CH4 (0.3%) selectivity with DME conversion of 92% in DME SR at 400 °C.

Techno-economic assessment of hydrogen production via dimethylether steam reforming and methanol steam reforming

ABSTRACT The present work reports the techno-economic analysis of hydrogen generation using Dimethyl Ether Steam Reforming (DMESR) and Methanol Steam Reforming (MSR) processes. For both processes, steady-state simulation models were developed using Aspen Plus. The two processes are analysed by taking into account the kinetics of the Cu/ZnO/Al2O3 catalyst for MSR and Cu–Ni/γ-Al2O3 catalyst for DMESR in an RPLUG model simulated as a Fixed Bed Reactor (FBR) at a temperature of 250°C and pressure 20 bar. The work dives into heat integration opportunities to reduce the operating cost of the two processes. The article also provides a gist of the approximate cost to produce hydrogen by the two processes by taking into consideration the cost of equipment and utilities involved. It is found that the TAC for DMESR is marginally higher than MSR mainly because of the higher cost of utilities involved. It was also found that NPV for MSR is comparatively higher than DMESR. The article also provides TAC for Selective Methanation of Carbon Monoxide (SMC) for both processes with the purpose of minimising CO.

The role of promoters in Cu/Acid‐MMT catalysts for production of hydrogen via steam reforming of dimethyl ether

AbstractBackgroundThe steam reforming of dimethyl ether (DME) is one of the promising technologies for high‐efficiency hydrogen production. The key issue for the steam reforming of DME is the development of catalysts with higher performance. In this study, a series of X‐Cu/Acid‐MMT (X = Co, Ni, Zr, Ce) catalysts were prepared via the impregnation method using Acid‐MMT obtained by montmorillonite activated with nitric acid (20 wt%) at 80 °C for 12 h as the support and metallic nitrate as precursor. The catalysts were characterized by XRD, H2‐TPR, XPS, N2O titration and N2 adsorption–desorption at low temperature.ResultsThe introduction of promoter X could reduce the interaction between Cu and the support, and more CuO was reduced to Cu0; meanwhile, it was beneficial for improving the dispersion of Cu. This would enhance the reaction rate of steam reforming of DME. Therefore, the introduction of promoter X significantly increased DME conversion, especially Ni‐Cu/Acid‐MMT presented the maximum DME conversion. However, Ni‐Cu/Acid‐MMT exhibited low H2 yield, high selectivity of CO and CH4 due to reverse water gas shift reaction and methanation reaction. Co‐Cu/Acid‐MMT catalyst presented the maximum H2 yield, high conversion of DME, relatively low selectivity of CH4 and better stability.ConclusionsThe introduction of promoters to Cu/Acid‐MMT catalyst improved the catalyst performance for the steam reforming of DME. Among these catalysts, Co‐Cu/Acid‐MMT exhibited remarkable catalytic performance, which is expected to be a potential catalyst for steam reforming of DME. © 2022 Society of Chemical Industry (SCI).

An autonomous fuel cell: Methanol and dimethyl ether steam reforming direct fed to fuel cell

Studies of reforming systems integrated with Fuel Cells are interesting for energy production in remote regions, especially to develop multi-fuel processors, which can be fed by more than one fuel with no need to modify the unit. In this work, an Autonomous Fuel Cell (AFC) system with methanol and/or Dimethyl Ether Steam Reforming (SR) was modeled and simulated in Aspen Plus, evaluating process variables, appropriate operational conditions, and the need for additional processes. The maximum hydrogen formed is H2/C = 3.0 (yield of 99.9%) and occurs generally with S/C ≥ 2 for several temperatures. The presence of a WGS reactor and a membrane for hydrogen purification was identified as vital to develop an AFC. In six situations that were studied with different operating conditions that meet the AFC operation, it was observed that the lowest temperature is preferable since it will consume the least amount of utility to maintain the SR.

Insights into Cu–Amorphous Silica–Alumina as a Bifunctional Catalyst for the Steam Reforming of Dimethyl Ether

The steam reforming of dimethyl ether (SRD) has been proved to be one of the most promising routes for on-site H2 production. However, the two-step consecutive nature of the SRD reaction makes the design of an efficient bifunctional catalyst a challenge. Herein, a series of Cu incorporated into amorphous silica–alumina (Cu–ASA) as integrated bifunctional catalysts for SRD were synthesized by the single-step complex decomposition method, and ammonium carbonate was confirmed to be an effective complex agent for dispersing Cu in ASA. The results indicated that the initial conversion of dimethyl ether and a H2 yield higher than 90% were achieved at 300 °C over the optimal catalyst. More importantly, a slightly decreased SRD performance with increasing time-on-stream was mainly caused by Cu sintering, and the synergetic effect between ASA and Cu played a crucial role in determining the activity, hydrogen yield, and stability of the integrated Cu–ASA bifunctional catalyst for SRD. These findings are helpful to develop a high-performance integrated bifunctional catalyst for the SRD reaction.

Hydrogen generation characteristics of reduced DME steam reforming catalysts according to heating methods

The purpose of this study is to investigate the hydrogen generation characteristics of H2-reduced dimethyl ether (DME) steam reforming (SR) catalysts using different heating processes. The effects of the H2 reduction temperature and space velocity were investigated to identify an optimal reaction environment. Both the resistive and induction heating methods were used. The catalysts were prepared by impregnating copper over a γ-Al2O3 support. The Cu/Al2O3 catalysts with different loading amounts of 5–15 wt% Cu exhibited different characteristics when subjected to hydrogen reduction. The variation in acidity had a dominant effect on the DME-SR activity, and 15Cu/Al2O3 that underwent hydrogen reduction treatment at 500 °C attained improved performance at low temperatures and low formation of by-products, allowing for the achievement of its highest H2 concentration of 74.08% at 375 °C. The induction heating reactor had an energy consumption that was about 25% lower than that of the resistive heating reactor.

Texture and acidity of amorphous silica-alumina regulated by the complex-decomposition method for steam reforming of dimethyl ether

In this work, amorphous silica-alumina composite (ASA) with varied compositions was synthesized via the complex-decomposition method with different complex agents. The XRD characterization revealed the amorphous nature of ASA composites regardless of the synthesis conditions. However, the acidity and the textural properties of ASA composites characterized by BET, Py-FTIR and NH3-TPD were significantly affected by the specific complex agent and amount, Si/Al molar ratio and calcination temperature. Among the investigated complex agents, the optimal amount of ammonium carbonate was the most efficient in tailoring both the textural and acidic properties of ASA. The hybrid of the synthesized ASA and a commercial Cu/ZnO/Al2O3 was studied for the steam reforming of dimethyl ether (SRD), and ASA synthesized by using ammonium carbonate as the complexing agent showed the optimal activity. Importantly, the synergetic effect between ASA and Cu/ZnO/Al2O3 was found to play a crucial role in determining the activity and stability of the bifunctional catalyst, and the partial oxidation of Cu0 to Cu+ induced from the ASA acidity had a great contribution to the deactivation of the bifunctional catalyst. These understandings are favorable for developing a more efficient solid acid for SRD.

Acid activation of montmorillonite and its application for production of hydrogen via steam reforming of dimethyl ether

A series of acid-activated montmorillonites (Acid-MMTs) were prepared via Na-montmorillonite treated with nitric acid solution at different treatment temperature and time. And the Acid-MMTs used as solid acid were physically mixed with commercial Cu/ZnO/Al2O3 to obtain bifunctional catalysts for steam reforming of dimethyl ether (SRD) reaction. The results showed that the structure, texture and acidity of Acid-MMTs were significantly changed compared with Na-MMT, which was dependent on the acid treatment conditions. The structure and acidity of Acid-MMTs obviously affected the SRD performance over bifunctional catalyst. The bifunctional catalyst composed of the Na-MMT activated in 20% nitric acid solution at 80°C for 12 h (Acid-MMT-80/12) and Cu/ZnO/Al2O3 exhibited the best SRD performance, with the dimethyl ether conversion and H2 yield reaching 97% and 94% under the conditions of p=0.1 MPa, t=350°C, GHSV=3000 h−1, respectively, and DME conversion and H2 yield remained basically constant in 10 h, indicating that the catalyst had better stability.

Standalone micro-reformer for on-demand hydrogen production from dimethyl ether

Entering a new era of sustainable energy generation and consumption, micro-fuel cells are showing great potential for providing high energy density to consumer electronics, and micro-reactor technology can indeed enable their integration by providing hydrogen on-demand from hydrocarbons. In this work, we present the design and fully scalable wafer-level fabrication of a MEMS-based catalytic micro-reactor tested in real-life operating conditions by means of a 3D printed ceramic housing. The device consists of an array of thousands of vertically aligned micro-channels, 500 μm in length and 50 μm in diameter, for an overall superficial area per unit volume of 120 cm2 cm−3 and it embeds a thin-film heater for efficient reaction start-up. For the first time, functionalization of the micro-reactor is entirely achieved by atomic layer deposition (ALD) and rapid thermal processing (RTP), resulting in the uniform coating of a Pt/Al2O3 heterogeneous catalyst hereby tested for steam reforming (SR) and partial oxidation (POX) of dimethyl ether (DME). Here, conversion rates up to 74% and hydrogen selectivity of ~60% are obtained by steam reforming at 650 °C, while a specific volumetric hydrogen production of 4.5 mLH2 mL−1DME cm−3REACTOR at 600 °C is obtained from DME POX.

Thermodynamic modelling of dimethyl ether steam reforming

Hydrogen is a promising clean energy strategy that can be obtained from the steam reforming of hydrogen-rich materials such as dimethyl ether (DME). In this study, the results of thermodynamic analysis of DME steam reforming were utilised as a framework for the development of correlations for predicting percentage molar yield of each species given a known set of inputs. Response surface methodology—historical data design was used for the work. The effect of temperature, pressure and steam to carbon ratio was shown to be significant in the process. Combinatorial effects of factors and the yield of various chemical species in the product stream were elucidated. The key contribution of this paper is the development of model predictors of all chemical species in the steam reforming of DME. All models developed were shown to be significant. These can afford for quick predictions given a known set of process inputs and can play an important role in the design of DME reforming systems.

Unravelling the role of ceria in improving the stability of Mo2C- based catalysts for the steam reforming of dimethyl ether

Ceria changes the reaction pathway and promotes the activity and stability of Mo2C in dimethyl ether steam reforming.

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.

A highly active and stable Pt modified molybdenum carbide catalyst for steam reforming of dimethyl ether and the reaction pathway

To improve the stability of molybdenum carbide catalysts in dimethyl ether steam reforming (DSR), the inactivation mechanism and the performance of Pt modified catalyst has been investigated. The Mo2C oxidation induced by H2O is verified to be the main reason of catalytic deactivation. After modified with Pt, the H2 production rate and selectivity are greatly enhanced, reaches 1605 μmol min−1·gcat−1 at 350 °C, in comparison to that of the Mo2C/Al2O3 catalyst. Moreover, the 2%Pt–Mo2C/Al2O3 catalyst is more stable with only 20% activity loss after 50 h on stream compares to the 73% activity loss in 12 h with Mo2C/Al2O3 catalyst. By means of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the enhancement brought by Pt is ascribed to the consumption acceleration of intermediate oxygen species on catalyst surface and the decline of onset temperature of DSR reaction. It is expected that these findings can lead us to more practical molybdenum carbide catalysts in DSR.

Thermodynamic analysis of fuel composition and effects of different dimethyl ether processing technologies on cell efficiency

Solid oxide fuel cell (SOFC) is one of the most attractive energy conversion systems, while dimethyl ether (DME) is an alternative clean fuel, and thus the application of DME in SOFC has great attraction. Fuel compositions are mainly determined by fuel processing technologies, which can affect the cell efficiency. In this paper, the relationships among fuel composition, oxygen to carbon (O/C) ratio, carbon deposition and cell efficiency are investigated for different DME processing technologies. According to the calculated results, SOFC with steam reforming of DME has the highest efficiency at the same O/C ratio and equivalent fuel utilization, while for catalytic partial oxidation of DME, the cell efficiency decreases rapidly with the increase of O/C ratio. The efficiency of SOFC with CO2 reforming of DME decreases with the increase of O/C ratio, especially at high O/C ratio and low equivalent fuel utilization. When the O/C ratio is 1.5, solid carbon can't be formed, where the cell efficiencies are 51.7% for steam reforming of DME, 42.2% for DME reforming with H2O and O2, 32.7% for catalytic partial oxidation of DME, 49.3% for DME reforming with anode off-gas and 41.4% for CO2 reforming of DME at 80% equivalent fuel utilization.

Effect of γ-Al2O3 characteristics on hydrogen production of Cu/γ-Al2O3 catalyst for steam reforming of dimethyl ether

The objective of this study is to investigate the effect of the characteristics of γ-Al2O3 on hydrogen production and the stability of the Cu/γ-Al2O3 dimethyl ether steam reforming (SR) catalyst. Cu/γ-Al2O3 catalysts with various amounts of Cu were prepared by impregnation into γ-Al2O3 having different surface characteristics. The results demonstrate that the characteristics of the γ-Al2O3 support greatly affect the hydrogen production performance of the Cu-based/γ-Al2O3 DME SR catalysts, and that carbon deposition increased with the amount of CO and CH4 that come from oxygenates (DME/MeOH) as coke precursors formed by DME hydrolysis reaction. The concentration of H2 produced with Cu10/γ-Al2O3(200) was up to 72%, and it was higher than that of the other catalysts. The BET of Al2O3 affects different coke resistance and durability, in which the lowest BET shows severely deactivation and weak coke resistance compared to BET 140 and 200. Cu10/γ-Al2O3(200) and (140) catalysts were more durable and stable than Cu10/γ-Al2O3(70) due to lower carbon deposition on the catalyst surface.

Zinc oxide modified HZSM-5 as an efficient acidic catalyst for hydrogen production by steam reforming of dimethyl ether

The parent HZSM-5 was modified with a series content of ZnO via the incipient impregnation method by using Zn(NO3)2·6H2O as a precursor. And the ZnO-modified HZSM-5 physically mixed with a commercial Cu/ZnO/Al2O3 was investigated as a bifunctional catalyst for steam reforming of dimethyl ether (DME). The samples were systematically characterized by XRD, FT-IR, N2 adsorption–desorption at low temperature, and NH3-TPD techniques. It was found that the introduction of ZnO would slightly influence the structure and crystallinity of the parent HZSM-5. Furthermore, the type (Lewis and Bronsted acid) and distribution (strong and weak acid sites) of acid could be adjusted by altering the content of ZnO, which took responsible for the DME conversion, H2 yield, and selectivity of the carbon-containing products. As a result, an efficient catalyst for steam reforming of DME was obtained by adjusting the content of ZnO.

Insights into the long-term stability of the magnesia modified H-ZSM-5 as an efficient solid acid for steam reforming of dimethyl ether

The long-term performance of the bifunctional catalyst composed of MgO-modified H-ZSM-5 and Cu/ZnO/Al2O3 for steam reforming of dimethyl ether (SRD) is studied under the same conditions. Although the surface chemical state and acid property of 1.55–2.47 wt% MgO modified H-ZSM-5 are almost the same, a significant impact of MgO contents on the stability of the bifunctional catalyst is observed from the 50 h SRD results. The initial dimethyl ether conversion (around 100%) and H2 yield (∼95%) over the optimal bifunctional catalyst with 2.17 wt% MgO modified H-ZSM-5 is still kept over 90% at 50 h. Combining the characterization data of spent catalysts and SRD results, the synergetic effect between the MgO-modified H-ZSM-5 and Cu/ZnO/Al2O3 is rigorously revealed as the key factor in determining the stability of the bifunctional catalyst for SRD. These results demonstrate that MgO-modified H-ZSM-5 is a promising and efficient solid acid for SRD.

Sputtered Cu-ZnO/γ-Al2O3 Bifunctional Catalyst with Ultra-Low Cu Content Boosting Dimethyl Ether Steam Reforming and Inhibiting Side Reactions

Dimethyl ether steam reforming (DME SR) is one of attractive technologies to online provide H2 for fuel cells in vehicles. Herein, we adopt a novel sputtering method to prepare a Cu-ZnO/γ-Al2O3 (Cu...

Insights into the CO Formation Mechanism during Steam Reforming of Dimethyl Ether over NiO/Cu-Based Catalyst

Steam reforming of dimethyl ether on Cu-based catalyst was experimentally studied. It is found that formation of H2 and CO2 occurred over Cu/γ-Al2O3/Al, while methanol decomposition to CO and H2 was the main reaction over Cu/Ni/γ-Al2O3/Al in methanol steam reforming (MSR), which is similar to that on metallic Ni. However, XPS results show that nickel species existed as an oxidation state (NiO) over Cu/Ni/γ-Al2O3/Al. Therefore, reaction pathways of MSR over Cu(111) and NiO/Cu(111) were further explored using theoretical density functional theory calculations, and it was found that different reactivities of CH2O* resulted in the distinct product selectivity. On Cu(111), CH2O* reacting with OH* to CH2OOH* is favored, while CH2O* prefers to dehydrogenate to H* and CO* directly on NiO/Cu(111). This provided further evidence on the experimental results and fundamental understanding on the role of NiO species in affecting the MSR mechanism, which was helpful for rational design of selective Cu-based catalysts.