The genesis of the active phase in Raney-type catalysts: the role of leaching parameters

Devred, François; Hoffer, Bram W.; Sloof, W.G.; Kooyman, Patricia J.; Langeveld, A.D. van; Zandbergen, H.W.

doi:10.1016/s0926-860x(02)00601-4

Cited by 46 publications

(29 citation statements)

References 7 publications

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“…As a consequence, the copper to zinc ratio is higher after the basic leaching and independent of the leaching time. The results confirm observations of Devred et al [28] who studied the influence of leaching parameters on the formation of active phases during the preparation of Raney metals.…”

Section: Catalyst Characterizationsupporting

confidence: 91%

Micro-structured string-reactor for autothermal production of hydrogen

Horny

Kiwi‐Minsker

Renken

2004

Chemical Engineering Journal

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Novel micro-structured string-reactor designed as catalytically active wires placed in parallel into a tube was developed. The small diameter of the channels (∼100 m) leads to a short radial diffusion time, a narrow residence time distribution (RTD), and a low pressure drop. This reactor was applied for the oxidative steam-reforming of methanol (OSRM) to produce hydrogen in autothermal mode for fuel cells. The heat generated during methanol oxidation at the reactor entrance is axially transferred to the reactor zone of the endothermic steam-reforming. The brass metal wires (Cu/Zn = 4/1) were used as precursors for the preparation of string-catalysts. The brass wires have high thermal conductivity (120 W/(m K)) and the chemical composition is similar to the active phase of the Cu/ZnO/Al 2 O 3 traditional catalyst during the steam-reforming of methanol. Brass-based string catalysts are obtained by metal/aluminium alloy formation on the outer surface of wires followed by an acid treatment leaching out aluminium. This treatment leads to an increase of the specific surface area (SSA) due to the formation of porous outer layer on the wire surface. The porous outer layer has the morphology of Raney metals. The catalysts were first tested for the steam-reforming of methanol and showed high activity together with selectivities close to 100% towards hydrogen and carbon dioxide. Then, the optimized catalyst was tested during the methanol partial oxidation (POX) and during OSRM. Oxygen was observed to be totally converted via total oxidation and therefore, higher methanol conversion in the OSRM together with CO 2 selectivity of 99% and H 2 selectivity of 60% were obtained.

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Section: Catalyst Characterizationsupporting

confidence: 91%

Micro-structured string-reactor for autothermal production of hydrogen

Horny

Kiwi‐Minsker

Renken

2004

Chemical Engineering Journal

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“…Sorbitol could be considered as the hydrogenation product of glucose originating from the hydrolysis of maltose, [14] and the uncertain by-product was possibly formed via the dehydration reaction between glucose molecule and maltitol molecule (Scheme 2). The poor selectivity of Raney Ni could be attributed to the presence of residual alumina, [15] which served as acidic sites to catalyze the hydrolysis of maltose and the condensation between glucose and maltitol. [14] Although Raney Ni showed the highest S act , it still exhibited a much lower R H m than the amorphous alloy catalysts even under its optimum reaction conditions (393 K, 3.0 MPa, and 4 h) because of its lower intrinsic activity (R H S ).…”

Section: Catalytic Performancesmentioning

confidence: 99%

A Novel Ruthenium‐Phosphorus Amorphous Alloy Catalyst for Maltose Hydrogenation to Maltitol

Chu

Liu

et al. 2008

Adv Synth Catal

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A ruthenium-phosphorus (Ru-P) amorphous alloy catalyst was prepared by chemical reduc-À ] in aqueous solution and was applied to the liquid-phase hydrogenation of maltose. In comparison with other reference catalysts, Ru-P showed significant activity as evident in the order: Ru-P > Ru-B @ Ni-P > Co-P @ Raney Ni. Furthermore, this catalyst was also found to be more durable during this hydrogenation process. Special emphasis was laid on a comparative study of Ru-P and Ru-B catalysts to get an insight into the excellent catalytic performances of Ru-P.

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“…Temperature was kept constant within ±1°C of the desired temperature during the reaction as the temperature increased quickly due to the exothermic reaction [21]. When the required temperature was reached, a definite amount of the alloy was added.…”

Section: Methodsmentioning

confidence: 99%

“…leaching temperature, solid/liquid ratio and alkaline concentration and reaction time) greatly affect the catalytic performance of the catalysts [3,9,21]. The experiments were performed at the temperatures of 10, 25 and 40°C in NaOH solutions of 2, 4 and 6 M. Also, solid/liquid ratio was 2, 3 and 4 g/L.…”

Section: Methodsmentioning

confidence: 99%

Leaching process in the preparation of Raney cobalt catalyst

Abacıoğlu

Salt

2010

Reac Kinet Mech Cat

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Raney metal type Co-Al alloy consisting of 36 wt% Co and 64 wt% Al was prepared by melting cobalt and aluminum metals in argon atmosphere, and then by solidification the resultant intermetallic compound. Raney Co catalyst was prepared by leaching out aluminum from Co-Al alloy with sodium hydroxide solution. The effects of reaction temperature (10, 25 and 40°C), concentration of sodium hydroxide (2, 4 and 6 M), solid to liquid ratio (2, 3 and 4 g/L) on the leaching were investigated by following the increase of the amount of aluminum in the reaction mixture. The structural properties of the alloy and the catalyst were examined by XRF, SEM, XRD and BET analysis. The kinetic model best fitting the experimental results among various models was determined.

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The genesis of the active phase in Raney-type catalysts: the role of leaching parameters

Cited by 46 publications

References 7 publications

Micro-structured string-reactor for autothermal production of hydrogen

Micro-structured string-reactor for autothermal production of hydrogen

A Novel Ruthenium‐Phosphorus Amorphous Alloy Catalyst for Maltose Hydrogenation to Maltitol

Leaching process in the preparation of Raney cobalt catalyst

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