A non-pyrophoric Ni catalyst (NP Ni) was prepared by alkali leaching of a Ni 50 Al 50 alloy using only ~1/10 of the amount of NaOH required for the preparation of the conventional Raney Ni catalyst. Characterizations reveal that the as-prepared NP Ni catalyst can be looked at as a Ni-Al(OH) 3 composite catalyst with Ni in the metallic state and Al(OH) 3 in forms of gibbsite and bayerite. After 100 h on stream in aqueous-phase reforming (APR) of ethylene glycol, phase transformation of gibbsite and bayerite to flake-like boehmite occurred, along with the growth of Ni crystallites and partial oxidation of metallic Ni to Ni(OH) 2 . Under identical reaction conditions for APR of ethylene glycol, the NP Ni catalyst is about 40-52% more active than Raney Ni in terms of the conversion of ethylene glycol to gas products, which is attributed to the stabilizing effect of hydrated alumina on Ni crystallites. The higher selectivity toward H 2 and the lower concentration of CO in the product gas on the NP Ni catalyst are attributed to the activation of water by hydrated alumina which is beneficial to the water-gas shift reaction.
KOH is Key: A one‐pot multistep approach is developed for the production of COx‐free H2 from biomass‐derived oxygenates. By using KOH as process modifier, a gas product containing exclusively 97 % of H2 and 3 % of methane is obtained from aqueous‐phase reforming of ethylene glycol in a single reactor over an unmodified non‐precious‐metal catalyst. This approach enables the production of H2 in an energy‐efficient and cost‐effective manner.
The adsorption and reaction of dipropyl sulfide on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) were
studied in ultrahigh vacuum by means of X-ray photoelectron spectroscopy (XPS). Dipropyl sulfide physisorbed
on both substrates at 103 K. At 173 K, for Raney Ni, the physisorbed dipropyl sulfide disappeared and the
chemisorbed dipropyl sulfide was formed, accompanied by the commencement of C−S bond scission. At the
same temperature, for RQ Ni, however, physisorbed dipropyl sulfide was still present, bearing comparable
intensity with the chemisorbed dipropyl sulfide, and no atomic S from C−S bond scission was detectable.
The lower reactivity of RQ Ni toward dipropyl sulfide is attributed to lattice expansion of the Ni crystallites
in RQ Ni posed by rapid quenching. By 473 K, the C 1s peak intensity was totally lost, leaving only atomic
S on both substrates. The implication of this work on the regeneration and design of metallic Ni-based
adsorbents was addressed.
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