Steam Reforming Of Methanol Research Articles

Improved charge transfer and morphology on Ti-modified Cu/γ-Al2O3/Al catalyst enhance the activity for methanol steam reforming

The metal-oxide interaction has been considered as an effective factor for catalytic performance in methanol steam reforming. In this work, Ti modified Cu/γ-Al2O3/Al catalyst was prepared by anodization technology. It is found that the addition of Ti can largely increase the surface area of the carrier and thus improve the dispersion of copper. The co-existence of Ti4+ and Ti3+ makes the charge transfer between Cu and Ti easier, which improves the redox performance of copper. The DFT calculations reveal that Ti also enhance the adsorption capacity of water and methanol on the surface of the catalysts. Besides, Ti also reduce the acid density on the carrier, inhibit methanol dehydration reaction and thereby reduce the selectivity of the DME. The optimal catalyst CuTi1.9/γ-Al2O3/Al achieves nearly 100% conversion at 275 °C, while the methanol conversion of Cu/γ-Al2O3/Al is 82%. And the H2 output of CuTi1.9/γ-Al2O3/Al reached 69.17 mol/(kgcat·h) at 300 °C.

High-efficient solar-driven hydrogen production by full-spectrum synergistic photo-thermo-catalytic methanol steam reforming with in-situ photoreduced Pt-CuOx catalyst

Synergy between the intrinsic photon and thermal effects from full-spectrum sunlight for H2 production is considered to be central to further improve solar-driven H2 production. To that end, the photo-thermo-catalyst that demonstrates both photoelectronic and photothermal conversion capabilities have drawn much attention recently. Here, we propose a novel synergistic full-spectrum photo-thermo-catalysis technique for high-efficient H2 production by solar-driven methanol steam reforming (MSR), along with the Pt-CuOx photo-thermo-catalyst featuring Pt-Cu/Cu2O/CuO heterojunctions by Pt-mediated in-situ photoreduction of CuO. The results show that the H2 production performance rises superlinearly with increasing light intensity. The optimal H2 production rate of 1.6 mol g−1 h−1 with the corresponding solar-to-hydrogen conversion efficiency of 7% and the CO selectivity of 5% is achieved under 15 × sun full-spectrum irradiance (1 × sun = 1 kW m−2) at 180 °C, which is much more efficient than the previously-reported Cu-based thermo-catalysts for MSR normally operating at 250∼350 °C. These attractive performances result from the optimized reaction kinetics in terms of intensified intermediate adsorption and accelerated carrier transfer by long-wave photothermal effect, and reduced activation barrier by short-wave photoelectronic effect, due to the broadened full-spectrum absorbability of catalyst. This work has brought us into the innovative technology of full-spectrum synergistic photo-thermo-catalysis, which is envisioned to expand the application fields of high-efficient solar fuel production.

Achieving strong thermal stability in catalytic reforming of methanol over in-situ self-activated nano Cu2O/ZnO catalyst with dual-sites of Cu species

Copper based catalysts with excellent catalytic activity and hydrogen selectivity are widely used in methanol steam reforming (MSR). Yet, the hydrogen pre-reduction step results in hydrogen consumption and energy loss. In addition, the copper nanoparticles are extremely sintered (≥ 300 ℃) to render deactivation caused by the low Taman temperature of 407 ℃. To solve these specific problems, a nano Cu2O/ZnO catalyst with double copper active sites (Cu+ and Cu0) was designed. Cu+ with high reducibility could lessen the catalyst's self-activation time using methanol as the hydrogen carrier. Nano ZnO could support and scatter the active components, effectively prevent the sintering and aggregation of copper nanoclusters. Furthermore, the synergy between the carrier and the active components existed according to H2-TPR. In order to maximize the hydrogen yield and reduce undesirable CO, the quadratic polynomial functions were established to investigate the effects of temperature (T = 450–550 °C), molar ratio of steam to carbon (SCMR=1.5–2.5 mol/mol), and weight-hour space velocity (WHSV=4–6 h−1) on H2 yield (HY) and potential H2 yield (PHY) based on the response surface methodology (RSM) in conjunction with the Box-Behnken design (BBD). The HY (92.1%) and PHY (97.2%) were obtained under T = 550 °C, SCMR= 2.0 mol/mol, and WHSV= 4.7 h−1. Within 36 h, stable 99% hydrogen selectivity was attained at 550 °C. The activity is induced by a new double copper active reaction path substituting the conventional Cu0-determined path. These discoveries provide a basis for the development of efficient catalysts with commercial potential.

Minimizing Heat Transfer Resistance in an Integrated Methanol Steam Reformer Designed Using Space-Filling Curves

Conventional packed bed methanol steam reformers producing hydrogen for PEM fuel cells have an inherent trade-off problem between simultaneously attaining high methanol conversion and low carbon monoxide production, owing to high thermal resistance in the packed bed. A sophisticated reformer design using Hilbert’s space-filling curves is proposed and demonstrated using CFD modeling and simulation. The reactor comprises a flow-through domain divided into two interdigitating but nonmixing continua that are separated by a thin wall, providing high interfacial area for heat transfer and surface reactions. The interfacial wall is modeled as coated with catalyst for performing reforming on one side and fuel cell anode exhaust hydrogen combustion on the other side. About 84% methanol conversion and CO production less than 2% was achieved due to remarkable reduction in heat transfer resistance. External mass transfer controlled the reactor operation, while reaction kinetics exhibited nontrivial influence on reactor performance.

Production of hydrogen via methanol steam reforming over mesoporous CeO2–Cu/KIT-6 nanocatalyst: Effects of polar aprotic tetrahydrofuran solvent and ZrO2 promoter on catalytic performance

In the present study, the preparation of CeO2–Cu/KIT-6 catalysts was made by the conventional impregnation approach using a polar protic solvent (ethanol), and a polar aprotic solvent (tetrahydrofuran (THF)) as well as ethylene glycol (EG)-assisted impregnation approach. The impact of the zirconium promoter on the catalytic activity of the catalyst was evaluated in methanol steam reforming (MSR). The characterization of the prepared catalysts was carried out by XRD, XRF, BET, FE-SEM, H2-TPR, and TEM analyses. According to the characterization outcomes, the application of THF as an impregnation solvent and incorporation of ZrO2 remarkably reduced the size of Cu particles and increased the dispersion of metal species. ZrO2-promoted CeO2–Cu/KIT-6 catalyst prepared using the THF solvent showed the most suitable catalytic activity with hydrogen selectivity of 99.8%, methanol conversion of 96%, and CO selectivity of 0.7% at 300 °C. Furthermore, the catalytic stability of the synthesized catalysts was investigated over 100 h of operation.

Precisely deposited Pd on ZnO (002) facets derived from complex reduction strategy for methanol steam reforming

Pd/ZnO catalysts are promising for onboard hydrogen production through methanol steam reforming (MSR), but their selectivity still requires improving. In this research, a flower-like spherical ZnO material with mainly exposed (002) facet was prepared through surfactant-assisted hydrothermal method. The surfactant tartaric groups also serve as coordinating groups to adsorb Pd2+ to form a complex, which is further reduced to metallic Pd. By virtue of preferential adsorption of the surfactant on (002) facet, Pd particles are confined to (002) facet. The calcined PdO-ZnO-T-X catalyst shows highly dispersed PdO nanoparticles. Characterization results suggest that strong interaction between ZnO (002) facet and small PdO particles can facilitate complete PdO reduction and PdZn formation, and can effectively retard PdZn decomposition under oxidizing atmosphere. This research discloses structure-performance relationship of Pd/ZnO catalysts and provides a novel strategy for further improving their MSR performance.

Hydrogen production via aqueous-phase reforming for high-temperature proton exchange membrane fuel cells - a review.

Aqueous-phase reforming (APR) can convert methanol and other oxygenated hydrocarbons to hydrogen and carbon dioxide at lower temperatures when compared with the corresponding gas phase process. APR favours the water-gas shift (WGS) reaction and inhibits alkane formation; moreover, it is a simpler and more energy efficient process compared to gas-phase steam reforming. For example, Pt-based catalysts supported on alumina are typically selected for methanol APR, due to their high activity at temperatures of circa 200°C. However, non-noble catalysts such as nickel (Ni) supported on metal-oxides or zeolites are being investigated with promising results in terms of catalytic activity and stability. The development of APR kinetic models and reactor designs is also being addressed to make APR a more attractive process for producing in situ hydrogen.This can also lead to the possibility of APR integration with high-temperature proton exchange membrane fuel cells. The integration can result into increased overall system efficiency and avoiding critical issues faced in the state-of-the-art fuel cells integrated with methanol steam reforming.

Properties of Bulk In-Pt Intermetallic Compounds in Methanol Steam Reforming.

Heterogeneous catalysts are often complex materials containing different compounds. While this can lead to highly beneficial interfaces, it is difficult to identify the role of single components. In methanol steam reforming (MSR), the interplay between intermetallic compounds, supporting oxides and redox reactions leads to highly active and CO2‐selective materials. Herein, the intrinsic catalytic properties of unsupported In3Pt2, In2Pt, and In7Pt3 as model systems for Pt/In2O3‐based catalytic materials in MSR are addressed. In2Pt was identified as the essential compound responsible for the reported excellent CO2‐selectivity of 99.5 % at 300 °C in supported systems, showing a CO2‐selectivity above 99 % even at 400 °C. Additionally, the partial oxidation of In7Pt3 revealed that too much In2O3 is detrimental for the catalytic properties. The study highlights the crucial role of intermetallic In−Pt compounds in Pt/In2O3 materials with excellent CO2‐selectivity.

Methanol steam reforming over PdZn/ZnAl2O4/Al2O3 in a catalytic membrane reactor: An experimental and modelling study

A catalytic membrane reactor equipped with Pd–Ag metallic membranes and loaded with PdZn/ZnAl 2 O 4 /Al 2 O 3 catalytic pellets was tested for the methanol steam reforming reaction (S/C = 1) aimed at producing a pure hydrogen stream for PEM fuel cell feeding. The catalyst was prepared in two steps. First, commercial γ-Al 2 O 3 pellets were impregnated with ZnCl 2 and calcined at 700 °C to obtain a ZnAl 2 O 4 shell, and subsequently impregnated with PdCl 2 and reduced at 600 °C to obtain PdZn alloy nanoparticles. The catalyst was tested both in a conventional packed bed reactor and in a catalytic membrane reactor. A 3D CFD non-isothermal model with mass transfer limitations was developed and validated with experimental data. The reactions of methanol steam reforming, reverse water-gas shift and methanation were modeled under different pressure, temperature and feed load values. The model was used to study and simulate the CMR under different operation conditions. • PdZn/ZnAl 2 O 4 /Al 2 O 3 catalytic pellets designed for the methanol steam reforming. • Kinetic analysis in catalytic packed bed reactor and catalytic membrane reactor. • 3D CFD non-isothermal model with mass transfer limitations developed and validated. • Catalytic membrane reactor simulated under different operation conditions.

Proposal of a novel modular photo-thermo-reactor system for cascaded hydrogen production from methanol steam reforming

In the present work, a novel modular photo-thermo-reactor (MPTR) for high-efficient and low-cost hydrogen production from methanol steam reforming (MSR), benefitting from synergistic photo-thermo-catalysis (PTC) with Pt/CuO catalyst and thermo-catalysis (TC) with Cu/ZnO/Al2O3 catalyst in a cascade way using composite catalyst beds, is proposed. The theory–experiment-based multiphysics model covering the optical, flow, thermal and chemical sub-processes is established in order to optimally design the MPTR. The predicted design-point performance of MPTR indicates that the PTC reaction breaks the limitation of normal TC reaction, which leads to the currently highest overall solar-to-hydrogen efficiency up to 24.1%, with the corresponding annual hydrogen production of 1211 Nm3/m2 in Xi’an, China. Moreover, a location-sensitive economic analysis model is built, considering not only the conventional factors, such as investment, stock and M&O costs, but also the location related factors, such as the solar resources and transportation cost. The results demonstrate that the levelized cost of hydrogen (LCOH) could be reduced as low as 3.82 $/kg if the location of the proposed MPTR system is appropriately chosen.

3D-Printed Regular-Porous Structure with Trapezoidal Multiple Microchannels as Combustion Reaction Support for the Autothermal Methanol Steam Reforming Microreactor for Hydrogen Production

3D-Printed Regular-Porous Structure with Trapezoidal Multiple Microchannels as Combustion Reaction Support for the Autothermal Methanol Steam Reforming Microreactor for Hydrogen Production

Direct ink writing of 3D SiC scaffold as catalyst support for thermally autonomous methanol steam reforming microreactor

Methanol steam reforming (MSR) has been proven to be a feasible approach for in-situ hydrogen production. This paper designed a novel thermally autonomous MSR microreactor with regular-shaped pores SiC scaffold as catalyst support. The SiC scaffolds with four different pore sizes were fabricated by direct ink writing (DIW) of polycarbosilane-based solution. After post processing, the printed ceramic precursor scaffolds shrank homogeneously and converted into porous SiC ceramic, which maintain original regular-shaped pores. The experimental results showed that the microreactor with smaller pore-sized SiC scaffold catalyst support had the highest hydrogen production value while poor characteristics in fluid flow. At an inlet flow rate of 60 μl/min and reaction temperature of 280 °C, the microreactor with 0.5 mm pore-sized SiC scaffold can produce the average hydrogen of 53.85 ml/min with methanol conversion of 82.88%. After 24 h of continuous operation, the SiC scaffold still had great hydrogen production, demonstrating remarkable stability as catalyst support for MSR hydrogen production system. This work demonstrates that ceramic scaffold catalyst support fabricated by DIW is a promising method for the development of MSR microreactors for regulation of the fluid flow and hydrogen production performances.

The role of effectiveness factor on the modeling of methanol steam reforming over CuO/ZnO/Al2O3 catalyst in a multi-tubular reactor

A pseudo-homogeneous model for the methanol steam reforming process was developed based on reaction kinetics over a CuO/ZnO/Al 2 O 3 catalyst and non-adiabatic heat and mass transfer performances in a co-current packed-bed reactor. A Thiele modulus method and an intraparticle distribution method were applied for predicting the effectiveness factors for main reactions and providing insights into the diffusion-reaction process in a cylindrical catalyst pellet. The results of both methods are validated and show good agreements with the experimental data, but the intraparticle distribution method provides better predictions. Results indicate that increases in catalyst size and bulk fluid temperature amplify the impact of intraparticle diffusion limitations, showing a decrease in effectiveness factors. To satisfy the requirements of a high temperature polymer electrolyte membrane fuel cell stack, the optimized operating conditions, which bring the methanol and CO concentrations to less than 1 % vol in the reformate stream, are determined based on the simulation results. • One-dimensional pseudo-homogeneous model of a packed-bed methanol steam reformer. • Two methods to obtain approximate solutions of the catalytic effectiveness factor. • Validation of reaction kinetics and effectiveness factors with experimental data. • Effects of main operating parameters on the intraparticle heat and mass transfer. • Optimized conditions to obtain less than 1% of CH 3 OH and CO in reformate gas.

Induced activation of the commercial Cu/ZnO/Al2O3 catalyst for the steam reforming of methanol

Induced activation of the commercial Cu/ZnO/Al2O3 catalyst for the steam reforming of methanol

Synthesis, characterization, and methanol steam reforming performance for hydrogen production on perovskite-type oxides SrCo1-xCuxO3-δ

The perovskite-type metal oxides SrCo1-xCuxO3-δ (x = 0, 0.2, 0.4, 0.6, 0.8, 1) powders, synthesized by ethylenediaminetetraacetic acid (EDTA) sol-gel method, were investigated for hydrogen production from methanol steam reforming (MSR). The synthesized catalysts were characterized by a scanning X-ray diffraction (XRD), an energy-dispersive X-ray spectroscope (EDS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller specific area (BET), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the perovskite structure of the catalyst sample after reduction treatment is destroyed, resulting in significant changes in oxygen species and the element chemical environment, which is consistent with the XRD results. The experimental results show that the doping content of cobalt and the reaction conditions have affect the catalytic performance of the catalysts. SrCo0.8Cu0.2O3-δ displays the maximum hydrogen production (about 4.6 × 10−3 mol/gcat/min). The Co-doping in the B-site may have an influence on the water-gas shift reaction, which leads to changes in the CO/CO2 selectivity in the gas products. The optimum reaction conditions (the reaction temperature = 600 °C; the molar ratio of water to methanol (W/M) = 2: 1; the feed flow rate = 3 ml/h) with the best comprehensive catalytic performance were determined by MSR experiments. In addition, the morphological characteristics of porous structure, small particle size, and rough surface contribute to the improvement of the catalytic performance of the catalyst in the MSR for H2 production.

ZnO–ZnCr2O4 composite prepared by a glycine nitrate process method and applied for hydrogen production by steam reforming of methanol

To address climate change, the energy crisis, and global warming, hydrogen (H2) can be used as a potential energy carrier because it is clean, non-toxic and efficient. Today, the mainstream industrial method of H2 generation is steam reforming of methanol (SRM). In this process, a zinc-based commercial catalyst is usually used. In this work, a ZnO–ZnCr2O4 catalyst was successfully synthesised by the glycine nitrate process (GNP) and developed for use in H2 production by SRM. The specific surface area, porous structure and reaction sites of the zinc-based catalyst were effectively increased by the preparation method. The as-combusted ZnO–ZnCr2O4 composite catalyst had a highly porous structure due to the gas released during the GNP reaction process. Moreover, according to the ZnO distribution and different G/N ratios, the specific surface area (SBET) of the as-combusted ZnO–ZnCr2O4 catalyst varied from 29 m2 g−1 to 46 m2 g−1. The ZnO–ZnCr2O4 composite catalyst (G/N 1.7) exhibited the highest hydrogen production, 4814 ml STP min−1 g-cat−1, at a reaction temperature of 450 °C without activation treatment. After activation, the ZnO–ZnCr2O4 composite catalyst achieved hydrogen production of 6299 ml STP min−1 g-cat−1 at a reaction temperature of 500 °C. The hydrogen production performance of the ZnO–ZnCr2O4 composite powder was improved by the uniform addition of ZnO to ZnCr2O4. Based on the performance, this ZnO–ZnCr2O4 composite catalyst has great potential to have industrial and economic impact due to its high efficiency in hydrogen production.

Comparison of a commercial water-gas shift catalyst and La modified Cu-based catalysts prepared by deposition-precipitation in methanol steam reforming.

Herein, a performance analysis of La-doped copper-based catalysts (CuO/ZrO2/La-Al2O3) in methanol steam reforming (MSR) was conducted and compared with a commercial low temperature water-gas shift catalyst (HiFUEL W220) to produce H2 with low CO selectivity. The physicochemical properties of as-obtained catalysts were characterized by N2 adsorption, XRD, and ICP-OES. Effect of calcination temperature (750 °C and 1000 °C) on the properties of mixed oxide support (La-Al2O3) were discussed based on catalytic activity. The optimum conditions of H2O/CH3OH ratio (1.0-3.0), space-time ratio (WFA0) (40-120 kg s mol-1), and reaction temperature (180-310 °C) were evaluated by a parametric study using the commercial catalyst (HF220). Additionally, thermodynamic equilibrium calculations of experimentally identified components by using Aspen HYSYS process simulation software were also performed to analyze MSR process. The results were indicated that the calcination temperature significantly affected the structural properties and the activity with respect to CO selectivity. An increasing trend in CO selectivity for catalysts with supports calcined at 750 °C and a decreasing trend for catalysts with supports calcined at 1000 °C were observed. Hence, CZ30LA750 and CZ30LA1000 catalysts were selected to attain low CO selectivity and comparable activity when compared to other catalysts and the simulated thermodynamic calculation results.

Efficient methanol steam reforming over ZnCeZrOx: the unique role of cerium

Zn1Ce1Zr9Oxis a ternary solid solution with Zn and Ce doped into the lattice of ZrO2, which is more active and stable than the counterpart without cerium doping in steam reforming of methanol.

DFT study on the catalytic role of α-MoC(100) in methanol steam reforming

In this work, we investigated the methanol steam reforming (MSR) reaction (CH3OH+H2O →CO2+3H2) catalyzed by α-MoC by means of density functional theory calculations. The adsorption behavior of the relevant intermediates and the kinetics of the elementary steps in the MSR reaction are systematically investigated. The results show that, on the α-MoC(100) surface, the O−H bond cleavage of CH3OH leads to CH3O, which subsequently dehydrogenates to CH2O. Then, the formation of CH2OOH between CH2O and OH is favored over the decomposition to CHO and H. The sequential dehydrogenation of CH2OOH results in a high selectivity for CO2. In contrast, the over-strong adsorption of the CH2O intermediate on the α-MoC(111) surface leads to its dehydrogenation to CO product. In addition, we found that OH species, which is produced from the facile water activation, help the O−H bond breaking of intermediates by lowering the reaction energy barrier. This work not only reveals the catalytic role played by α-MoC(100) in the MSR reaction, but also provides theoretical guidance for the design of α-MoC-based catalysts.

CuxNiy/2TiO2-CeO2 Catalysts for Effective Syngas Production in Methanol Steam Reforming

We provide an efficient method aimed at obtaining suitable H2/CO syngas by adjusting the composition of CuxNiy/2TiO2-CeO2 catalysts and the corresponding reaction temperature in methanol steam reforming (MSR).