DME Steam Research Articles

Modeling and Numerical Simulation of Hydrogen Production from Dimethyl Ether Steam Reforming

In order to study the steam reforming process of dimethyl ether, a kind of reformer reactor with thermal jacket, heat pipe and catalytic reaction bed was designed. The effects of reaction gas temperature, molar ratio of water to ether and the structure parameters of the reactor on the conversion of dimethyl ether, the yield of hydrogen, the hydrogen concentration at the outlet of the reactor and the concentration of CO2 were investigated experimentally. The mathematics and power of the reactor were established Learn model The COMSOL software was used to simulate it. The simulation results showed the temperature distribution, mass distribution, DME conversion and hydrogen production in DME steam reforming process. These simulation results will provide useful data for the design and operation of small scale catalytic reforming bed reactors.

2-22.ジメチルエーテル(DME)からの都市ガス製造におけるDME改質反応条件と反応速度に関する検討((6)転換利用II,Session 2 天然ガス・メタンハイドレート等)

2-22.ジメチルエーテル(DME)からの都市ガス製造におけるDME改質反応条件と反応速度に関する検討((6)転換利用II,Session 2 天然ガス・メタンハイドレート等)

Kinetics Study and Simulation of DME Steam Reforming Reaction

A CFD (computational fluid dynamics) model has been presented to simulate the steam reforming reaction of DME in this study. A three-dimensional numerical model introduced by the commercial software COMSOL was used to investigate the fluid flow of reformer bed and heating tubes, the energy transport of reformer bed and heating tubes, and the mass transport of reformer bed. The governing equations in the model consist of conservations of mass, momentum, energy and chemical species. In order to optimize the process of reaction, the steam to DME ratio, the inlet temperature, and porosity were investigated. The simulation results showed the changes of temperature distribution, DME conversion and hydrogen production of the steam reforming reaction with different operation conditions.

A computational model of hydrogen production by steam reforming of dimethyl ether in a large scale CFB reactor. Part II: Parametric analysis

This study presents a computational parametric analysis of DME steam reforming in a large scale Circulating Fluidized Bed (CFB) reactor. The Computational Fluid Dynamic (CFD) model used, which is based on Eulerian–Eulerian dispersed flow, has been developed and validated in Part I of this study [1]. The effect of the reactor inlet configuration, gas residence time, inlet temperature and steam to DME ratio on the overall reactor performance and products have all been investigated. The results have shown that the use of double sided solid feeding system remarkable improvement in the flow uniformity, but with limited effect on the reactions and products. The temperature has been found to play a dominant role in increasing the DME conversion and the hydrogen yield. According to the parametric analysis, it is recommended to run the CFB reactor at around 300 °C inlet temperature, 5.5 steam to DME molar ratio, 4 s gas residence time and 37,104 ml gcat−1 h−1 space velocity. At these conditions, the DME conversion and hydrogen molar concentration in the product gas were both found to be around 80%.

Effect of Operating Conditions on Dimethyl Ether Steam Reforming over a CuFe2O4/γ-Al2O3 Bifunctional Catalyst

A study is conducted on the effect the operating variables (temperature, space-time, steam/DME molar ratio, DME partial pressure) have on DME steam reforming over CuFe2O4/γ-Al2O3 bifunctional catalyst in order to obtain high H2 yield with minimum deactivation by coke. The experiments were carried out in a fluidized bed reactor under the following operating conditions: 250–400 °C; space-time, 0.029–1.16 gcatalyst h/gDME; steam/DME molar ratio, 3–8; DME partial pressure, 0.05–0.2 atm. A good balance is required between the reaction rates for both steps, DME hydrolysis (on the acid function) and the steam reforming of methanol (on the metallic function), in order to minimize the methanol concentration in the reaction medium because it promotes deactivation of the metallic function. A high steam/DME molar ratio minimizes deactivation. A steady H2 yield of 82% along 10 h is obtained at 350 °C, steam/DME molar ratio of 4, and space-time of 0.58 gcatalyst h/gDME.

Dynamic Model Study and Analysis of DME Auto-Thermal Steam Reforming Reaction

Through the study of the kinetics of dimethyl ether steam reforming reaction, a two-dimensional model of the reactor is established. At the same time, rate equations of simplified elementary reactions of DME steam reforming reaction are deduced by the mechanism of Langmuir-Hinshel-wood, and the rate constants are obtained by correcting the pre-exponential factor of Arrhenius equation. Finally, the analog data of DME steam reforming reaction under a variety of conditions are obtained, and making a simulation diagram. The two-dimensional model is substantially correct because of the analog data more in line with a variety of knowledge.

Effect of combining metallic and acid functions in CZA/HZSM-5 desilicated zeolite catalysts on the DME steam reforming in a fluidized bed

A study has been carried out on the effect of combining the metallic (CuO–ZnO–Al2O3) and acid (HZSM-5 zeolite treated with NaOH) functions, and of their mass ratio, on the kinetic performance in the steam reforming of dimethyl ether (SRD). The runs have been conducted in a fluidized bed reactor in the 225–325 °C range, and the reaction indices (dimethyl ether and methanol conversions, and H2 and CO yields) have been explained based on the physico-chemical properties of the catalyst.A suitable synergism between dimethyl ether hydrolysis and methanol reforming steps requires striking a balance between acidity and the number and dispersion of metal sites, as happens in the catalyst prepared by wet physical mixing with a mass ratio of 1:1 between the metallic function and the acid one. This catalyst allows obtaining high values of dimethyl ether conversion and H2 yield in the 275–300 °C range by minimizing the CO formation rate and deactivation by coke.

Enhancement of catalytic activity over TiO2-modified Al2O3 and ZnO–Cr2O3 composite catalyst for hydrogen production via dimethyl ether steam reforming

The dimethyl ether steam reforming (DME SR) was carried out over the composite catalyst of ZnO–Cr2O3 coupled with Al2O3, TiO2 or TiO2–Al2O3 in the microreactor. The results showed that the catalytic activities were greatly enhanced over the composite catalyst of ZnO–Cr2O3 combined with TiO2–Al2O3 (ZnCr–TiAl) in comparison to those combined with Al2O3 or TiO2 in DME SR. By evaluating the catalytic activity of solid acids in DME hydrolysis, it was proposed that the better performance of TiO2–Al2O3 in DME hydrolysis contributed to the superior activity of ZnCr–TiAl in DME SR, indicating a higher DME hydrolysis activity favored DME SR. In view of the characterization of N2 physisorption, scanning electron microscope, X-ray diffraction and NH3 temperature-programmed desorption, the promotion effect of TiO2 on both DME hydrolysis and steam reforming was discussed in terms of the modification effect of TiO2 on the acid properties of Al2O3 surface. The acid strength or total acid amount was enhanced by the addition of different TiO2 content. In the 150h medium stability test, there was no obvious deactivation for ZnCr–TiAl catalyst with the H2 production rate of 345 mol h−1 kgcat−1 and the CO selectivity in the dry reformate remained below 6%. The characterization results of the used catalyst revealed that no change in the crystalline phase and size occurred on the spent catalyst.

Prominent enhancement of Mn or Co addition on the performance of Cu-Ce-O catalyst used for H 2 production via dimethyl ether steam reforming

The Mn or Co promoted Cu-Ce-O catalysts were prepared by citric acid complexation, and used for the catalytic production of hydrogen via the route of dimethyl ether steam reforming (DME SR). Multiple techniques such as X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectra (XPS), temperature-programmed reduction by H 2 (H 2-TPR), CO-pulse chemisorption and thermal gravimetry/differential thermal analysis (TG/DTA) were employed for catalyst characterization. It is revealed by the results of XRD, XPS and XAFS that in the spent catalysts the copper species mainly exist as Cu 0 and Cu +. The addition of Co or Mn could enhance both the dispersion and the reducibility of copper species, significantly increasing the DME conversion and H 2 yield at the temperature of 400 °C or below. At higher temperature, the H 2 yield over Cu-Ce-Co-O is almost the same as that for Cu-Ce-O, due to the side reactions of CH 3OH decomposition and/or DME steam reforming to syngas. Addition of Mn to Cu-Ce-O can increase both DME conversion and H 2 yield in the whole temperature region of 300–450 °C. Much higher CO 2 selectivity is achieved over the Mn promoted catalyst. XPS and CO-pulse chemisorption results indicate that Cu-Ce-Mn-O catalyst contains more Cu + species, which determines its novel catalytic performance including higher DME conversion and higher H 2 yield.

Effective parameters for DME steam reforming catalysts for the formation of H 2 and CO

Recently, DME has received attention as a clean fuel and is now considered an alternative fuel for diesel engines. DME diesels need de-NOx catalysts such as LNT (Lean NOx Trap) and SCR (Selective Catalytic Reduction) systems. DME is an attractive source of hydrogen because it can be stored easily and is a good transportation fuel. Hydrogen and CO enriched gas as a reductant was used with the LNT catalyst in order to reduce NOx emissions. The steam reforming catalyst of DME was used to formation of hydrogen. It has been reported that Cu-based catalysts have high selectivity and activity in the steam reforming of DME. This research used 600 cPsi cordierite as a catalyst, which was coated with copper. The catalysts were made via a sol–gel and impregnation methods. The formation of H 2 and CO under the prepared catalysts was tested by a model gas. Experimental parameters were considered; the space velocity (SV) and concentrations of H 2O, O 2, and CO 2 were evaluated. The Cu 30%/γ-Al 2O 3 catalyst from the sol–gel method exhibited high and stable activity in the production of hydrogen from the steam reforming of DME. Both DME conversion and the selectivity of hydrogen were affected by SV and the concentrations of H 2O, O 2, and CO 2.

B107 DMEを利用した中低温廃熱の化学再生用触媒の実験的研究(OS3 省エネルギー・コジェネ技術),動力エネルギーシステム部門20周年,次の20年への新展開)

This work aims to realize combined heat and power (CHP) system enhanced by chemical recuperation of the unused waste heat at around 300 degree C that is commonly found in many industries. This system can "upgrade" the unused waste heat to electric energy by endothermic reaction of DME steam reforming and can save the fuel consumption and reduce CO_2 emission. We successfully prepared the catalyst customized to this purpose. DME steam reforming is the sequential reaction which consists of DME hydrolysis and methanol decomposition or steam reforming, and a few research reported that solid acid promotes the former reaction. We experimented with several combinations of zeolite and γ-alumina for solid acid and CoFe-spinel, CuMnCrK, CuMn-spinel and LaPd/CeO_2 for the latter reactions. The test results showed that zeolite had higher activity for DME hydrolysis and LaPd/CeO_2 selectively produced CO by suppressing CO shift reaction at 300 degree C. The LHV of reformed gas increased by 8.7% compared to that of DME fuel.

Steam Reforming of Dimethyl Ether over Cu/ZnO/ZrO<sub>2</sub> and γ-Al<sub>2</sub>O<sub>3</sub> Mixed Catalyst Prepared by Extrusion

Steam reforming of dimethyl ether, DME, over Cu/ZnO/ZrO2 and γ-Al2O3 mixed catalysts prepared by the extrusion technique was investigated. The catalysts were characterized by BET, pore-size distribution measurements, N2O chemisorption, powder X-ray diffraction, and SEM-EDX analysis. The effect of reaction temperature on catalyst life time was investigated. Steam reforming of DME over the extruded catalyst proceeded above 623 K. The major reaction products were H2 and CO2 with relatively small amounts of CO and CH4. DME steam reforming was not restricted by the equilibrium limitation of DME hydration to CH3OH, suggesting that CH3OH produced was subsequently reformed into H2 and CO2 over the catalyst. The catalyst suffered from thermal deactivation at higher temperatures; mainly caused by a reduction in Cu dispersion in the Cu/ZnO/ZrO2 catalyst. Incorporation of ZrO2 into Cu/ZnO may stabilize Cu dispersion and increase the stability of the extruded catalyst for long-term operation.

DME（ジメチルエーテル）改質触媒の耐久性向上検討

DME（ジメチルエーテル）改質触媒の耐久性向上検討

OS4-2 ジメチルエーテルを燃料とする化学再生ガスタービンシステム用改質器の設計(OS4 省エネルギー・小型分散電源・コジェネ技術,分散と集中の共存)

OS4-2 ジメチルエーテルを燃料とする化学再生ガスタービンシステム用改質器の設計(OS4 省エネルギー・小型分散電源・コジェネ技術,分散と集中の共存)

Effect of support on the activity of Ga 2O 3 species for steam reforming of dimethyl ether

The effects of various supports on the catalytic activity of Ga 2O 3 for the steam reforming of DME have been examined. Among the various supported Ga 2O 3 catalysts, Ga 2O 3/TiO 2 showed the highest DME steam reforming activity in terms of DME conversion and H 2 yield. The results from XRD, surface area and XPS indicate that the dispersion of Ga 2O 3 strongly depends on the catalyst support. A correlation between the XPS results and the DME steam reforming activity reveals that there is some electronic interaction between Ga 2O 3 and the support element. The large electronic interaction found in Ga 2O 3/TiO 2 leads to the best catalytic performance among all the catalysts.