Issue 24, 2023

On the role of potassium in Prussian blue analogue-derived Mn–Co catalysts applied in the CO hydrogenation to higher alcohols

Abstract

The lowering of the K content of phase-pure Mn–Co-derived Prussian blue analogue (PBA)-based catalysts applied in higher alcohol synthesis was achieved by an additional washing step and by substituting K+ cations by (NH4)+ cations prior to synthesis. Adding the washing step to the microemulsion-assisted co-precipitation route resulted in a decrease from 3.1 wt% to 0.6 wt% K after pyrolysis, whereas substitution achieved a K content of only 0.2 wt%. During pyrolysis the washed PBA precursor decomposed in a single step resulting in a sharp mass loss at 540 °C, whereas the NH4-based precursor gave rise to a major broad peak at 390 °C. Correspondingly, strong changes of the textural and structural properties of the resulting porous carbon matrix with embedded Co0 were observed. Under HAS conditions the formation of bulk Co2C in close contact with Cohcp occurred as shown by in-depth structural investigations of the spent catalysts. Washing resulted in an increased total oxygenate selectivity up to 35%, whereas the CO2 selectivity of the substituted sample was decreased to 15% at a temperature of 260 °C, a pressure of 60 bar and a H2/CO ratio of 1. Both methods led to higher CO conversion, and the lowered K content of 0.6 wt% also resulted in a significantly higher selectivity of primary and secondary alcohols of 20% and 11%, respectively, due to the presence of more acidic Co–N–C sites.

Graphical abstract: On the role of potassium in Prussian blue analogue-derived Mn–Co catalysts applied in the CO hydrogenation to higher alcohols

Supplementary files

Article information

Article type
Paper
Submitted
10 Jul 2023
Accepted
01 Nov 2023
First published
07 Nov 2023

Catal. Sci. Technol., 2023,13, 6968-6980

On the role of potassium in Prussian blue analogue-derived Mn–Co catalysts applied in the CO hydrogenation to higher alcohols

P. Telaar, P. Diehl, T. Herrendorf, S. Schaefer, W. Kleist and M. Muhler, Catal. Sci. Technol., 2023, 13, 6968 DOI: 10.1039/D3CY00957B

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