Active Pt/CeO2 catalysts prepared by an alcohol-reduction process for low-temperature CO-PROX reaction

Carla Moreira Santos Queiroz,Estevam Vitorio Spinacé,Jorge Moreira Vaz,Ana Rita Noborikawa Paiva,Rodolfo Molina Antoniassi,Arthur Pignataro Machado

doi:10.1007/s40243-019-0155-y

Abstract

Pt/CeO2 catalysts were prepared with 0.5 and 1 wt% of Pt loadings by an alcohol-reduction process using a solution of ethylene glycol and water as a reducing agent and solvent. The obtained catalysts were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy. Transmission electron micrographs showed Pt nanoparticles with average sizes of 2.2 and 2.4 nm for Pt content of 0.5 and 1 wt%, respectively. The preferential oxidation of carbon monoxide in hydrogen-rich stream (CO-PROX reaction) was studied in the temperature range of 25–150 °C. Pt/CeO2 catalysts showed maximum CO conversions in the range of 80–98% and CO2 selectivity in the range of 50–70% at 50 °C.

Highlights

Nowadays, the hydrogen production worldwide is mainly employed in the ammonia synthesis reaction and there is an increasing interest as a clean combustible option for fuel cell technology [1]
The carbon monoxide (CO)-SMET process tends to be more controllable, when compared to CO-PROX, since the CO and CO2 methanation reactions are less exothermic than H2 and CO oxidations; the H 2 consumption could be higher by about two times compared to the H 2 consumed for H 2O formation during CO-PROX processing [4,5,6,7]
23, 24], H2-temperature-programmed reduction (TPR) profiles of Pt/CeO2 catalysts showed three regions: the first one, in the range of 100–300 °C due to the reduction of PtOx species to Pt(0) and/or to CeOx species directly bonded to Pt reducing at lower temperatures; the second in the range of 300–600 °C assigned to the reduction of superficial C eOx species; and the third in the region above 600 °C due to the bulk reduction of CeO2

Summary

Introduction

The hydrogen production worldwide is mainly employed in the ammonia synthesis reaction and there is an increasing interest as a clean combustible option for fuel cell technology [1]. Some processes have been used to remove CO from H2-rich mixtures like pressure swing adsorption (PSA) that requires large capital investments and employ physic-sorbents to produce a very pure H 2 stream but with H 2 recovery values between 75 and 85% [1, 4, 5]. Another process is the methanation of CO (CO-MET), which operates at 300–400 °C, but causes significant loss of the produced hydrogen (10–15%) because of the unselective methanation of C O2 present in the reformate gas [1]. The CO-PROX process could avoid the hydrogen and energy loss, oxidizing CO at lower

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Results and discussion

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Conclusions

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