Dynamic Structure of a Working Methanol Steam Reforming Catalyst: In Situ Quick-EXAFS on Pd/ZnO Nanoparticles

2011 ◽  
Vol 2 (5) ◽  
pp. 428-433 ◽  
Author(s):  
Karin Föttinger ◽  
Jeroen A. van Bokhoven ◽  
Maarten Nachtegaal ◽  
Günther Rupprechter
Keyword(s):  
Steam Reforming ◽  
Zno Nanoparticles ◽  
Dynamic Structure ◽  
Methanol Steam Reforming ◽  
Reforming Catalyst ◽  
Quick Exafs

scholarly journals Influence of the ZrO2 Crystalline Phases on the Nature of Active Sites in PdCu/ZrO2 Catalysts for the Methanol Steam Reforming Reaction—An In Situ Spectroscopic Study

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1005
Author(s):  
Daniel Ruano ◽  
Beatriz M. Pabón ◽  
Càtia Azenha ◽  
Cecilia Mateos-Pedrero ◽  
Adélio Mendes ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Surface Composition ◽  
Ambient Pressure ◽  
Chemical Properties ◽  
Spectroscopic Studies ◽  
Metal Species ◽  
Methanol Steam Reforming ◽  
Reaction Products

In this work, the electronic properties of the metal sites in cubic and monoclinic ZrO2 supported Pd and PdCu catalysts have been investigated using CO as probe molecule in in-situ IR studies, and the surface composition of the outermost layers has been studied by APXPS (Ambient Pressure X-ray Photoemission Spectroscopy). The reaction products were followed by mass spectrometry, making it possible to relate the chemical properties of the catalysts under reaction conditions with their selectivity. Combining these techniques, it has been shown that the structure of the support (monoclinic or cubic ZrO2) affects the metal dispersion, mobility, and reorganization of metal sites under methanol steam reforming (MSR) conditions, influencing the oxidation state of surface metal species, with important consequences in the catalytic activity. Correlating the mass spectra of the reaction products with these spectroscopic studies, it was possible to conclude that electropositive metal species play an imperative role for high CO2 and H2 selectivity in the MSR reaction (less CO formation).

scholarly journals The Promoting Effect of Ni on Glycerol Hydrogenolysis to 1,2-Propanediol with In Situ Hydrogen from Methanol Steam Reforming Using a Cu/ZnO/Al2O3 Catalyst

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 412 ◽  
Author(s):  
Yuanqing Liu ◽  
Xiaoming Guo ◽  
Garry Rempel ◽  
Flora Ng
Keyword(s):  
Steam Reforming ◽  
Molecular Hydrogen ◽  
Biodiesel Production ◽  
Precipitation Method ◽  
Methanol Steam Reforming ◽  
Phase Reaction ◽  
Promoting Effect ◽  
High Hydrogen ◽  
Al2o3 Catalyst

Production of green chemicals using a biomass derived feedstock is of current interest. Among the processes, the hydrogenolysis of glycerol to 1,2-propanediol (1,2-PD) using externally supplied molecular hydrogen has been studied quite extensively. The utilization of methanol present in crude glycerol from biodiesel production can avoid the additional cost for molecular hydrogen storage and transportation, as well as reduce the safety risks due to the high hydrogen pressure operation. Recently the hydrogenolysis of glycerol with a Cu/ZnO/Al2O3 catalyst using in situ hydrogen generated from methanol steam reforming in a liquid phase reaction has been reported. This paper focusses on the effect of added Ni on the activity of a Cu/ZnO/Al2O3 catalyst prepared by an oxalate gel-co-precipitation method for the hydrogenolysis of glycerol using methanol as a hydrogen source. It is found that Ni reduces the conversion of glycerol but improves the selectivity to 1,2-PD, while a higher conversion of methanol is observed. The promoting effect of Ni on the selectivity to 1,2-PD is attributed to the slower dehydration of glycerol to acetol coupled with a higher availability of in situ hydrogen produced from methanol steam reforming and the higher hydrogenation activity of Ni towards the intermediate acetol to produce 1,2-PD.

Temperature dependence of Cu–Al spinel formation and its catalytic performance in methanol steam reforming

2017 ◽  
Vol 7 (21) ◽  
pp. 5069-5078 ◽  
Author(s):  
Yajie Liu ◽  
Shaojun Qing ◽  
Xiaoning Hou ◽  
Fajie Qin ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Steam Reforming ◽  
Catalytic Performance ◽  
Methanol Steam Reforming ◽  
Spinel Formation ◽  
Synthetic Temperature

Synthetic temperature strongly influences the properties of Cu1−3xVxAl2+2xO4. Active Cu generated in situ can be stabilized by defect spinels.

scholarly journals Ανάπτυξη καταλυτών κοβαλτίου για αναμόρφωση μεθανόλης

2016 ◽  
Author(s):  
Ευτυχία Παπαδοπούλου
Keyword(s):  
Specific Surface ◽  
Steam Reforming ◽  
Methanol Decomposition ◽  
The Other ◽  
Inert Gas ◽  
Co2 Production ◽  
Methanol Steam Reforming ◽  
Metallic Cobalt ◽  
In Situ Xrd

Methanol is an attractive option for storage and transportation of chemical energy. In thiscontext, methanol steam reforming is being considered as an interesting route for hydrogenproduction, since it can take place at lower temperatures in comparison with reforming of otherorganic compounds. Copper-based catalysts are considered as reference catalysts for methanolsteam reforming because they combine high activity and selectivity towards hydrogen production.On the other hand, cobalt-based catalysts have not been studied extensively for this reaction.The present work refers to the investigation of cobalt–manganese catalysts prepared throughpyrolysis of the corresponding fumarate or gluconate salts in the reaction of methanol reforming.The corresponding catalysts were prepared either by pyrolysis of the salts under inert gas flow inthe temperature range of 500-700oC or via oxidative treatment of the salts at 500oC.Catalysts characterization was performed by in situ XRD, BET, SEM and TPR techniques.It was found that mixed cobalt-manganese fumarate salts are useful precursors leading to catalystswith different structure depending on the type of surrounding atmosphere during activation.Activation in air leads to formation of CoMn spinel oxides, while activation in inert gas(pyrolysis) leads to structures containing metallic cobalt, MnO and residual carbon. Controlledoxidation of pyrolyzed samples leads to surface oxidized materials, which get reduced at muchlower temperatures compared to spinels.Combination of in-situ XRD, H2-TPR and methanol-TPR has led to identification of thevarious stages of catalyst reduction. These are: surface reduction, spinel reduction to (Co2+,Mn2+)O and reduction of Co2+ to Co0. It was also found that catalysts produced by pyrolysis arealmost fully reduced. The specific surface area of catalysts prepared from pyrolysis of fumaricsalts was ~200 m2 g-1 regardless of pyrolysis temperature, while the specific surface area of preoxidizedcatalysts was significantly lower in then range 16-34 m2 g-1.Methanol steam reforming products were CO, CO2, H2, while CH4 was also produced withselectivity less than 4%. Increase of cobalt loading leads to increase of methanol conversion, whilepre-oxidized catalysts get activated in the presence of the reaction mixture. Pyrolyzed catalysts aremore active than pre-oxidized ones and lead to product distributions according to thermodynamicpredictions at high reaction temperatures. Addition of potassium does not influence catalyticactivity but improves CO2 selectivity. Experimental findings indicate that methanol is initiallydecomposed to CO and H2 followed by the water-gas shift reaction.CO, H2, CO2, H2O and CH3OH adsorption was studied by TPD. No significant adsorption ofCO was observed on the catalysts following exposure to CO at room temperature, and this was~ vi ~also confirmed by FTIR. CO2 adsorption, on the other hand, was significant showing both weakand strongly-bound states. Hydrogen adsorption was found to be activated leading to both weakand strongly bound species on metallic cobalt and MnO. Water adsorption on pyrolyzed catalystsat 300oC is dissociative with simultaneous hydrogen production. Methanol TPD showed moleculardesorption at low temperatures and methanol decomposition towards CO and H2 at temperatureshigher than 125oC. CO2 desorption is also noticed at temperatures higher than 225oC. CO2originates either from CO oxidation with lattice oxygen or from the Boudouard reaction.Temperature programmed surface reaction of methanol in the absence of water shows initialadsorption of methanol at 30-90oC and methanol decomposition at temperatures higher than250oC. CO2 production is also observed at 250-350oC with simultaneously CO decrease. COproduction increases again above 350oC with simultaneously CO2 decrease. For highly reducedcatalysts CO2 production is attributed to the Boudouard reaction. When water is present, methanoldecomposition is accompanied by the WGS reaction, while carbon formation is prevented and thereaction activation energy decreases by 15-20 kJ mol-1.

scholarly journals Microstructural and Chemical Evolution and Analysis of a Self-Activating CO2-Selective Cu–Zr Bimetallic Methanol Steam Reforming Catalyst

2016 ◽  
Vol 120 (44) ◽  
pp. 25395-25404 ◽  
Author(s):  
Lukas Mayr ◽  
Norbert Köpfle ◽  
Bernhard Klötzer ◽  
Thomas Götsch ◽  
Johannes Bernardi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Steam Reforming ◽  
Methanol Steam Reforming ◽  
Reforming Catalyst
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