Insights into Deactivation and Regeneration of an Industrial Cu/Ni/Cr‐Al₂O₃ Catalyst During Aldehyde Hydrogenation

Abstract

The deactivation of a heterogeneous Cu/Ni/Cr‐Al2O3 aldehyde hydrogenation catalyst was studied using n‐nonyl aldehyde as model reactant. The reaction network was experimentally determined in batch experiments at 180 °C and 25 bar with either fresh or spent catalyst and also w/o the presence of the catalyst. Accelerated aging was applied to stress the fresh catalyst under model reaction conditions for characterization and comparison to a spent catalyst from an industrial plant. The catalyst structure and morphology were studied by XRD and TEM/EDX. The carbon residues that strongly adsorb on the catalyst surface during hydrogenation were analyzed by BET, TGA, extraction, and chemical disintegration. The amount of strongly adsorbed heavy hydrocarbons was 10 w % for the spent catalyst, causing a decrease in pore volume by 30 %. Regeneration of the catalyst was successfully conducted via oxidation of the carbon residues.

Remarkable Enhancement in Hydrogenation Ability by Phosphidation of Ruthenium: Specific Surface Structure Having Unique Ru Ensembles

“…2 Ni as a less noble metal for hydrogenation has been applied to practical use for various reactions, such as hydrogenation of unsaturated fatty acids, 3 nitroarenes, 4 and aldehydes. 5 However, in comparison with PGMs, severe reaction conditions, such as high temperature and hydrogen pressure, are typically required to obtain sufficient reaction rates. Therefore, drastic improvement in catalytic performance of less noble metals is an important task for both chemical science and human society.…”

“…However, because of their rarity, uneven distribution, and accordingly extremely high costs, it is highly required to replace these noble metals with less noble alternatives . Ni as a less noble metal for hydrogenation has been applied to practical use for various reactions, such as hydrogenation of unsaturated fatty acids, nitroarenes, and aldehydes . However, in comparison with PGMs, severe reaction conditions, such as high temperature and hydrogen pressure, are typically required to obtain sufficient reaction rates.…”

Effect of a Ce Promoter on Nonoxidative Dehydrogenation of Propane over the Commercial Cr/Al2O3 Catalyst

“…As a commercial catalyst, Cr/Al 2 O 3 has been widely used in dehydrogenation plants, (e.g., PDH), because of its high activity and selectivity for the reaction and its good mechanical stability. − From the prospect of further applications, appreciable improvement in catalytic performance of this catalyst is of importance. Different promoters, such as transition-metal oxides (e.g., Ni, Co, Cu), are generally employed to enhance catalytic performance of Cr/Al 2 O 3 because positive changes of the structure and physicochemical properties of the support are achieved with the addition of suitable promoters. − It has been reported that rare earth oxide ceria by Ce modification can increase catalytic performance of the supported catalysts by interacting with the support and/or increasing the dispersibility of the active metal component. , In fact, Ce was used as the promoter on the Cr-based catalysts for oxidative dehydrogenation of alkanes (e.g., isobutane, propane, and ethylbenzene) because of its excellent oxygen storage capacity, which can enhance the reduction–oxidation cycle between Cr 6+ and Cr 3+ species, thereby increasing the activity of the catalyst. − However, investigations of the interaction between Ce and Cr species, and the effects of Ce modification on the dispersion and distribution of the active Cr phase have seldom been concerned in these works, especially for propane nonoxidative dehydrogenation (PDH) reaction. From this point of view, using CeO 2 to modify Cr/Al 2 O 3 for PDH arouses our interest in the present research.…”

Highly active and noble-metal-alternative hydrogenation catalysts prepared by dealloying Ni–Si intermetallic compounds

“…However, because these noble metals are rare, unevenly distributed, and extremely expensive, the development of alternatives is strongly desired. 2 As a non-noble metal, Ni has been used in various hydrogenation reactions involving, for example, aldehydes, 3 nitroarenes, 4 aromatics, 5 and unsaturated fatty acids. 6 However, severe reaction conditions such as high temperatures and hydrogen pressures are typically needed to attain sufficient reaction rates.…”