Methanol Reformer Research Articles

Polybenzimidazole-Based High-Temperature Polymer Electrolyte Membrane Fuel Cells: New Insights and Recent Progress

High-temperature proton exchange membrane fuel cells based on phosphoric acid-doped polybenzimidazole membranes are a technology characterized by simplified construction and operation along with possible integration with, e.g., methanol reformers. Significant progress has been achieved in terms of key materials, components and systems. This review is devoted to updating new insights into the fundamental understanding and technological deployment of this technology. Polymers are synthetically modified with basic functionalities, and membranes are improved through cross-linking and inorganic–organic hybridization. New insights into phosphoric acid along with its interactions with basic polymers, metal catalysts and carbon-based supports are recapped. Recognition of parasitic acid migration raises acid retention issues at high current densities. Acid loss via evaporation is estimated with respect to the acid inventory of membrane electrode assembly. Acid adsorption on platinum surfaces can be alleviated for platinum alloys and non-precious metal catalysts. Binders have been considered a key to the establishment of the triple-phase boundary, while recent development of binderless electrodes opens new avenues toward low Pt loadings. Often ignored microporous layers and water impacts are also discussed. Of special concern are durability issues including acid loss, platinum sintering and carbon corrosion, the latter being critical during start/stop cycling with mitigation measures proposed. Long-term durability has been demonstrated with a voltage degradation rate of less than 1 μV h−1 under steady-state tests at 160 °C, while challenges remain at higher temperatures, current densities or reactant stoichiometries, particularly during dynamic operation with thermal, load or start/stop cycling.

Design of a methanol reformer for on-board production of hydrogen as fuel for a 3 kW High-Temperature Proton Exchange Membrane Fuel Cell power system

The method of Computational Fluid Dynamics is used to predict the process parameters and select the optimum operating regime of a methanol reformer for on-board production of hydrogen as fuel for a 3 kW High-Temperature Proton Exchange Membrane Fuel Cell power system. The analysis uses a three reactions kinetics model for methanol steam reforming, water gas shift and methanol decomposition reactions on Cu/ZnO/Al2O3 catalyst. Numerical simulations are performed at single channel level for a range of reformer operating temperatures and values of the molar flow rate of methanol per weight of catalyst at the reformer inlet. Two operating regimes of the fuel processor are selected which offer high methanol conversion rate and high hydrogen production while simultaneously result in a small reformer size and a reformate gas composition that can be tolerated by phosphoric acid-doped high temperature membrane electrode assemblies for proton exchange membrane fuel cells. Based on the results of the numerical simulations, the reactor is sized, and its design is optimized.

Sorption-enhanced chemical looping oxidative steam reforming of methanol for on-board hydrogen supply

Hydrogen is an indispensable energy carrier for the sustainable development of human society. Nevertheless, its storage, transportation, and in situ generation still face significant challenges. Methanol can be used as an intermediate carrier for hydrogen supplies, providing hydrogen energy through instant methanol conversion. In this study, a sorption-enhanced, chemical-looping, oxidative steam methanol-reforming (SECL-OSRM) process is proposed using CuO–MgO for the on-board hydrogen supply, which could be a promising method for safe and efficient hydrogen production. Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process. The effects of CuO/CH3OH, MgO/CH3OH, and H2O/CH3OH mole ratios and of temperature on H2 production rate, H utilization efficiency, CH3OH conversion, CO concentration, and system heat balance are discussed thoroughly. The results indicate that the system can be operated in auto-thermal conditions with high-purity hydrogen (99.50 vol%) and ultra-low-concentration CO (< 50 ppm) generation, which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells (LT-PEFMCs) with the SECL-OSRM process. The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H2O/CH3OH and MgO/CH3OH mole ratios.

Chemical looping induced CH3OH–H2-PEMFC scheme for fuel cell vehicle: Parameter optimization and feasibility analysis

In this work, a hybrid system combined with chemical looping methanol reformer (CL-reformer) and high-temperature proton exchange membrane fuel cell (HT-PEMFC) is proposed for the vehicle power supply. The Cu-based chemical looping induced methanol reforming is introduced to optimize the energy supply scheme of fuel cell vehicles. The start-up and working stages of the integrated system are comprehensively considered and simulated via the ASPEN Plus software. In start-up stage, the lattice oxygen participates the oxidative steam reforming of methanol, achieving auto-thermal hydrogen generation and Cu-based oxygen carrier (OC) reduction (Cu2+→Cu0), and the reduced OC can be regenerated by the air oxidation (Cu0→Cu2+); In working stage, the reduced OC (Cu0) plays the role of catalyzing methanol conversion, and the heat generated from HT-PEMFC stack can be recovered by the methanol reforming module. The effects of CL-reformer conditions on the methanol reformate quality and the performance of HT-PEMFC stack are investigated. Furthermore, the feasibility of maintaining thermally neutral of the integrated system is discussed. Simulation results indicate that the CL-reformer-HT-PEMFC system can achieve auto-thermal operation, in which the system electrical efficiencies of 21.6%–26.7% and 47.7% can be obtained at start-up and working stages, respectively.

A Computational Analysis of a Methanol Steam Reformer Using Phase Change Heat Transfer

A methanol steam reformer converts methanol and steam into a hydrogen-rich mixture through an endothermic reaction. The methanol reformer is divided into a reaction section and a heat supply section that transfers thermal energy from 200 to 300 °C. This study presents the behavior of the methanol steam reforming reaction using the latent heat of the steam. A numerical analysis was separately conducted for two different regimes assuming constant heat flux conditions. A methanol steam reformer is an annulus structure that has a phase change heat transfer from an outer tube to an inner tube. Different from the steam zone temperature in the tube, the latent heat of steam condensation decreases, and there is a gradual between-wall temperature decrease along the longitudinal direction. Since the latent heat of steam condensation is very sensitive to the requested heat from the reformer, it is necessary to consider a refined design of a methanol reformer to obtain a large enough amount of heat by steam condensation.

Synthesis of fine skeletal structure on Al–Cu–Co decagonal quasicrystals for hydrogen production through steam reforming of methanol

In the present investigation, we have reported the surface-microstructure, chemical composition and structural characteristics of the conventionally solidified Al65Cu15Co20 and Al65Cu20Co15 decagonal quasicrystals before and after chemical leaching treatment. The surface of the polycrystalline Al–Cu–Co decagonal phase was leached with 2.5 mol of Na2CO3 solution for the duration of 0.5 h, 2 h and 8 h. The leached surface was characterized by x-ray diffraction, scanning and transmission electron microscopy techniques. The energy dispersive x-ray analysis was employed to determine the chemical composition of the leached surface. After leaching treatment, the crystallographic structure of the leached surface was found to change from the quasicrystalline phase to the crystalline phases of Cu, Co and their oxides. The formation of the skeletal structure observed at the surface was attributed to the removal of Al atoms from the lattice points of the concerned decagonal quasilattice. This skeletal structure was found to contain porosities coexisting with finely distributed nano-particles of Cu, Co and Cu2O with sizes ranging from 10 to 28 nm. The 8 h leached surface containing these skeletal features has demonstrated excellent catalytic activity for steam reforming of methanol and it has led to hydrogen production at the rate of ~200 ml/g min at the reaction temperature of 580 K.

Mathematical modelling of the solar-driven steam reforming of methanol for a solar thermochemical micro-fluidized bed reformer: thermal performance and thermochemical conversion

A solar thermochemical reformer/receiver which combines a ST-μFB reformer and a catalytic bed of micro-sized particles offers a novel approach for the solar-driven catalytic steam reforming of methanol (SDCSR-MeOH) method. Heat transfer, mass transfer and solar thermochemical conversion performance have a great significance on the SDCSR-MeOH method due to high interfacial absorption surface of micro-sized particles. The solar radiation has been coupled to the ST-μFB reformer as a novel driving energy for conducting the endothermic reactions of methanol (CH3OH) inside ST-μFB reformer to produce solar H2. Solar H2 had won an important role as renewable feedstocks for different chemical processes and particularly in fuel cells applications. A non-isothermal mathematical model was described by a set of partial differential equations (PDEs) that couples to a complex kinetic model of the SDCSR-MeOH employing the Cu/ZnO/Al2O3 catalyst. The system of novel PDEs has been transformed into simpler system of ordinary differential equations using the coupled integral equation approach. Validation results demonstrate that the two validated cases for the reaction temperature against the simulated results by authors had reached a good fit as well as the solar thermochemical conversion of CH3OH. The temperature profiles of the gas phase, solid phase and ST-μFB reformer wall were simulated at three different positions from ST-μFB reformer. The reactant and product distributions inside ST-μFB reformer were analysed at two different reaction temperatures. The effect of the reaction temperature was studied on the conversion of CH3OH and yield of H2. In addition, the action of the weight hourly space velocity has been analysed on the conversion of CH3OH.

How to make use of methanol in green catalytic hydrogen production?

AbstractHydrogen production and storage as the core of novel hydrogen economy attract extensive attentions in both industry and academia. Methanol‐involved hydrogen production has been considered as an alternative strategy towards conventional methane stream reforming owing to its milder reaction condition and lower carbon footprint. Currently, it mainly includes three branches: (1) thermocatalytic methanol reforming, (2) photocatalytic methanol reforming, and (3) photocatalytic water reduction using methanol as a sacrificial agent. These branches with many similarities, however, are relatively independent in their development stages and research focuses, which seriously restricted the fundamental understanding of using methanol as both hydrogen carrier and catalytic accelerant in hydrogen production reactions. We summarize latest research progresses by expounding their respective advantages, common and individual problems, as well as methods and experiences being developed. The role of methanol and its feasibility in photocatalytic hydrogen production were also discussed from both reaction mechanism and system cost‐efficiency perspectives. Finally, frontiers of the three hydrogen production approaches are prospected, providing overall guidance for the potential application of economic and environmental sustainable methanol‐mediated hydrogen energy.

Disclosure of water roles in gliding arc plasma reforming of methanol for hydrogen production

AbstractTo disclose water roles in plasma reforming of methanol for hydrogen production, gliding arc discharge characteristics, optical emission spectra, and reaction behavior are investigated over a water concentration range of 0–95 mol%. It can be concluded that the varied reaction behavior with water concentration derives from three water roles as a homogeneous catalyst, CO oxidant, and side‐product. The former two roles of water are beneficial for hydrogen production. The side‐product role of water, accompanied by hydrocarbons formation, which is disadvantageous to hydrogen production and can be almost fully inhibited by the homogeneous catalysis of water at above 33 mol% H2O. As an oxidant, water conversion is controlled by the thermodynamic equilibrium at the gas temperature of arc.

How to choose endothermic process for thermochemical waste-heat recuperation?

The thermochemical waste-heat recuperation (TCR) systems by steam reforming of various hydrocarbon fuels are considered. A method for determining the TCR systems efficiency is proposed. The methodology is based on the determination of the heat recuperation rate and heat transformation coefficient. TCR due to steam reforming of methanol, ethanol, glycerol, propane, and methane was analyzed. To obtain the initial data for energy analysis of TCR systems, the thermodynamic analysis was performed. With the help of Aspen HYSYS was determined the synthesis gas composition and reaction enthalpy for all investigated variants. The investigation was performed for a wide temperature range from 400 to 1200 K, for the steam-to-fuel ratio of 1, and pressures of 1 bar. It was established that TCR due to the steam reforming of ethanol, glycerol, and propane in the temperature range above 800 K, it is possible to achieve complete recuperation of the exhaust after the furnace. As a results of investigation, the practical recommendations were given for choosing endothermic reaction for the thermochemical waste-heat recuperation systems: in the temperature range up to 600 K for TCR it is necessary to choose a methanol steam reforming reaction; in the temperature range from 600 to 1000 K - the reaction of steam reforming of ethanol and glycerol; in the temperature range above 1000 K - the reaction of steam reforming propane and methane.

Sorption enhanced steam reforming of methanol for high-purity hydrogen production over Cu-MgO/Al2O3 bifunctional catalysts

Sorption enhanced steam reforming of methanol (SESRM) can significantly promote the hydrogen production process with simultaneous CO2 sorption. The mechanical mixture of catalysts and sorbents as a conventional approach is complex and requires high temperatures for regeneration, which results in serious sintering of Cu-based catalysts. This paper describes a novel Cu-MgO/Al2O3 bifunctional catalysts (xCMA, x is denoted as the mass fraction of Cu, 0%–10%) via a sol–gel method for the SESRM process. We find that Cu species, including metallic Cu and Cu ions, co-exist on the catalyst. The metallic Cu on the catalyst surface is an active site for methanol steam reforming while the Cu ion in MgO lattice promotes the CO2 sorption capacity. Moreover, the incorporation of Cu ion into MgO also facilitates CO2 desorption by forming more bidentate carbonates. Due to the strong interaction between Cu and MgO, the Cu sintering is inhabited in comparison with the mechanical mixture of catalysts and sorbents. Meanwhile, MgO is found to induce more formate species to inhibit the generation of carbon monoxide. As a result, the optimal bifunctional catalyst, 8 wt% Cu-MgO/Al2O3 (8CMA) shows a superior performance in both catalytic reforming and CO2 sorption with a highest H2 selectivity of 99.3% and lowest CO selectivity (<0.15%) over 10 repeated cycles. This study suggests that the appropriate control of bifunctional catalysts can lead to powerful potential for high H2 production performance in SESRM.

CuFeO2–CeO2 nanopowder catalyst prepared by self-combustion glycine nitrate process and applied for hydrogen production from methanol steam reforming

Hydrogen (H2) is being considered as an alternate renewable energy carrier due to the energy crisis, climate change and global warming. In the chemical industry, hydrogen production is mainly accomplished by the steam reforming of natural gas. In the present study, CuFeO2–CeO2 nanopowder catalyst with a heterogeneous delafossite structure was prepared by the self-combustion glycine nitrate process and used for steam reforming of methanol (SRM). The precursor solution was fabricated from Cu–Fe–Ce metal-nitrate mixed with glycine and an aqueous solution. The prepared CuFeO2–CeO2 nanopowder catalyst was studied by different physical and chemical characterization techniques. The prepared CuFeO2–CeO2 nanopowder catalyst was immensely porous with a coral-like structure. The BET surface area measurement revealed that the specific surface area of as-combusted CuFeO2–CeO2 nanopowder varied from 5.6248 m2/g to 19.5441 m2/g. In addition, the production rate of CuFeO2–CeO2 was improved by adding CeO2 and adjusting the feeding rate of the methanol. The highest H2 generation rate of the CuFeO2–CeO2 catalyst was 2582.25 (mL STP min−1 g-cat−1) at a flow rate of 30 sccm at 400 °C. Hence, the high specific surface area of the 70CuFeO2–30CeO2 nanopowder catalyst and the steam reforming process could have a very important industrial and economic impact.

Feasible production of hydrogen from methanol reforming through single stage DC microplasma reactor

Plasma-assisted methanol reforming is an effective technology to produce hydrogen for various clean energy applications. In this study, hydrogen was produced from methanol reforming in a unique single stage microplasma reactor. Microplasma was produced between the capillary stainless steel tube electrodes by using high voltage direct current (DC) power supply. Blend of methanol and water was supplied to the microplasma reactor in a controlled flow rate using nitrogen as carrier gas. The effects of applied input power to the discharge and methanol feed rate on the performance of the plasma methanol decomposition were investigated. The experimental results showed that increasing the applied input power expressively increased the methanol conversion and hydrogen energy yield. In contrast, the increased feed rate significantly decreased the methanol conversion efficiency though it enriched the hydrogen energy yield. Under selective conditions, hydrogen energy yield of 24.14 g kW[Formula: see text] h[Formula: see text] was achieved with the conversion efficiency of 71% and 50% selectivity for H2, which is comparatively better than many of plasma-assisted methanol reforming processes. This investigation reveals that methanol reforming through a single stage microplasma reactor has the ability to produce hydrogen efficiently without coke formation at room-temperature and atmospheric pressure.

Antioxidative and stable PdZn/ZnO/Al2O3 catalyst coatings concerning methanol steam reforming for fuel cell-powered vehicles

In the real application of on-board hydrogen production for proton exchange membrane fuel cell (PEMFC)-powered vehicles, catalysts promoting steam reforming of methanol (SRM) for hydrogen production suffer frequent oxidation considering how intermittently vehicles are driven. To address this challenge, PdZn/ZnO/Al2O3 catalyst coatings with different molar ratios were prepared by the co-reduction method. The results showed a favorable effect of the high molar ratio of Zn to Pd on regenerating the PdZn intermetallic compounds by reducing the oxidized catalysts. This is because Zn atoms preferentially diffused into PdHx NPs along the PdHx 〈1 1 1〉 direction to form PdZn intermetallic compounds, and a high molar ratio of Zn to Pd guaranteed abundant Zn atoms along PdHx 〈1 1 1〉 direction during the reduction process. The oxidized PdZn/ZnO/Al2O3 catalyst coatings gradually recovered their catalytic activity due to the regeneration of PdZn intermetallic compounds. The PdZn/ZnO/Al2O3 catalyst coatings showed better stability than the reported catalysts and an excellent antioxidation ability in the SRM reaction, suggesting great potential for the on-board production of hydrogen for PEMFC-powered vehicles if coupled with a high-temperature water-gas shift reactor.

(Ni,Cu)/hexagonal BN nanohybrids – New efficient catalysts for methanol steam reforming and carbon monoxide oxidation

This work is aimed at the development of bimetallic (Ni0.2Cu0.8) catalysts with hexagonal boron nitride (h-BN) nanosheet (BNNS) supports and elucidating their catalytic activity in the methanol steam reforming and CO oxidation reactions. The hybrid Ni0.2Cu0.8/BN catalysts consist of curved h-BN nanosheets, up to 10–20 nm in lateral size, decorated with metallic nanoparticles, 3.0–8.2 nm in dimensions. The methanol conversion starts at ~20 °C and is nearly completed at 320 °C. The (Ni0.2Cu0.8)/BN nanohybrids exhibit high catalytic stability and high selectivity for CO2 over the whole temperature range. No carbon monoxide is detected during full methanol conversion. The possible mechanism of CO utilization during methanol reforming is proposed using ab initio calculations. The onset temperature of catalytic CO oxidation is 100 °C and full conversion is completed at 200 °C. These results indicate high catalytic efficiency of (Ni0.2Cu0.8)/BN nanohybrids in methanol steam reforming and CO oxidation reactions.

Homogeneous precipitation and urea-nitrate combustion preparation of nanostructured CuO/CeO2/ZrO2/Al2O3 oxides used in hydrogen production from methanol for fuel cells

The urea-nitrate combustion and homogeneous precipitation methods have been comparatively examined for the preparation of CuO/CeO2/ZrO2/Al2O3 catalysts. Their physicochemical properties, as well as their hydrogen production ability via the steam reforming of methanol, have been studied. Prepared catalysts were characterized using XRD, FESEM, EDX, BET, and FTIR analyses. Characterization analyses and catalytic performance studies showed that the preparation method plays an important role in the synthesis of catalysts. XRD analysis showed that the homogeneous precipitation method can prepare catalyst with smaller copper crystallites and better surface dispersion compared with the combustion synthesis method. EDX results illustrated homogenous dispersion of elements. BET and FESEM showed the surface area improvement and lower size distribution, respectively, during synthesis of catalysts by the homogeneous precipitation method. Catalytic performance study also proved that catalyst prepared by the homogeneous precipitation method had better methanol conversion at all temperatures, whereas the sample fabricated by the urea-nitrate combustion synthesis method produces less CO. The stability test showed that the catalyst synthesized by the combustion synthesis method was quite stable for the steam reforming of methanol.

Tannin-derived bimetallic CuCo/C catalysts for an efficient in-situ hydrogenation of lauric acid in methanol-water media

Integration of aqueous-phase reforming of methanol (APRM) into the production of value-added fatty alcohols via hydrogenation of fatty acids is an attractive and efficient process in biomass conversion. Herein, we present tannin-derived carbon-supported monometallic Cu/C, Co/C and bimetallic Cu-Co/C catalysts with different Cu/Co ratios for in situ hydrogenation of lauric acid in a methanol-water hydrothermal system. The catalysts were made by a simple mixture of tannin and the metal salts, followed by pyrolysis in an H2 atmosphere. Through synergism induced by Cu-Co interactions, the bimetallic Cu-Co/C catalyst with Cu/Co ratio of 1:4 (CuCo4/C) exhibits higher catalytic activity than monometallic Cu/C catalyst towards lauric acid conversion, as well as higher selectivity to lauryl alcohol than monometallic Co/C catalyst. The CuCo4/C catalyst is composed of metallic Cu, metallic Co, and amorphous carbon, characterized by high surface area (194.5 m2/g) and hierarchical structure. The obtained lauryl alcohol yield in the methanol-water hydrothermal system is significantly higher than other alcohol-water systems, namely ethanol, 1-propanol, and isopropanol hydrothermal systems, highlighting its higher generation rate of hydrogen. Also, the effects of process parameters including the quantity of methanol, catalyst loading and reaction time on the conversion of lauric acid were systematically studied and optimized.

Hydrogen generation from methanol reforming for fuel cell applications: A review

Methanol is regarded as an important liquid fuel for hydrogen storage, transportation, and in-situ generation due to its convenient conveyance, high energy density, and low conversion temperature. In this work, an overview of state-of-the-art investigations on methanol reforming is critically summarized, including the detailed introduction of methanol conversion pathways from the perspective of fuel cell applications, various advanced materials design for catalytic methanol conversion, as well as the development of steam methanol reformers. For the section of utilization pathways, reactions such as steam reforming of methanol, partial oxidation of methanol, oxidative steam reforming of methanol, and sorption-enhanced steam methanol reforming were elaborated; For the catalyst section, the strategies to enhance the catalytic activity and other comprehensive performances were summarized; For the reactor section, the newly designed steam methanol reformers were thoroughly described. This review will benefit researchers from both fundamental research and fuel cell applications in the field of catalyzing methanol to hydrogen.

Computation of effectiveness factor for methanol steam reforming over Cu/ZnO/Al2O3 catalyst pellet

A mathematical model was developed for a diffusion–reaction process in a spherical catalyst pellet contained in a heterogeneous packed bed reactor. The model developed was solved to predict the effectiveness factor and also to perform sensitivity analysis for steam reforming of methanol on Cu/ZnO/Al2O3 catalyst a source of hydrogen fuel. The method of orthogonal collocation was used to solve the resulting differential equation. At temperature below 473 K the effect on intra-particle diffusion limitation is reduced to the minimum indicated by the effectiveness factor being almost equal to one but as the temperature increases above 473 K there is considerable increase in the diffusion limitation effect. The effects of thermal conductivity, diffusion coefficient, catalyst size and surface temperature on effectiveness factor for the reaction process were also considered. Result indicates that catalyst size of 1.623,, times ,,10^{ - 4} m eliminates the effect of intra-particle diffusion resistance in the pellet. The variation of effectiveness factor with Thiele modulus, showing the asymptotic values, using power law and Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics, was predicted. The two reaction kinetics had almost the same magnitude of effectiveness factor at different Thiele modulus which indicates that they can adequately predict the reaction process.

Hydrogen Production on Cu-Ni Catalysts via the Oxy-Steam Reforming of Methanol

In this work, bimetallic Cu-Ni catalysts supported on binary oxides containing ZnO, ZrO2, CeO2 and Al2O3 were investigated in hydrogen production via the oxidative steam reforming of methanol (OSRM). Their physicochemical properties were extensively studied using various methods such as BET, TPR-H2, TPD-NH3, XRD, SEM-EDS, ToF-SIMS and XPS. The reactivity measurements showed that the active phase and support composition played an important role in the activity of the catalyst in the OSRM. The most active system at higher temperatures was 30% Cu–10% Ni/CeO2·Al2O3, with high catalytic activity attributed to the Cu0.8Ni0.2 alloy formation. In addition, the reactivity results showed that the most active catalyst exhibited high acidity and was easily reduced. At low temperatures, the best catalytic properties were exhibited by 30% Cu–10% Ni/ZrO2·Al2O3. The reactivity and physicochemical properties of the studied catalysts confirmed the crucial role of alloy composition on their catalytic properties in the oxy-steam reforming of methanol. The obtained results validate the possibility of using Cu-Ni catalysts for hydrogen production.