# Mechanochemically Engineered Bimetallic PtNi/CeO2 Catalysts for Enhanced Methane Steam Reforming

## TL;DR

Scientists made better methane reforming catalysts using a mechanical method, achieving higher efficiency and resistance to carbon buildup.

## Contribution

A mechanochemical synthesis method for PtNi/CeO2 catalysts that enhances methane conversion and coke resistance.

## Key findings

- Mechanochemically synthesized PtNi/CeO2 achieved 83.5% methane conversion at 700°C, outperforming traditional methods.
- Higher milling intensity improved catalytic activity by forming smaller NiO particles.
- Pt addition inhibited carbon deposition and caused surface segregation under reforming conditions.

## Abstract

Bimetallic PtNi/CeO2 catalysts were successfully
synthesized
via a mechanochemical approach, specifically ball milling, and evaluated
for methane steam reforming (MSR). A fractional factorial design of
experiments was employed to systematically explore the effects of
key milling parametersmilling frequency, milling time, and
ball-to-powder ratioon the catalysts’ structural properties
and catalytic performance. The catalysts were characterized by X-ray
diffraction, H2 temperature-programmed reduction, transmission
electron microscopy, and Raman spectroscopy. Catalytic activity tests
were performed in a plug flow reactor under a high gas hourly space
velocity (200,000 mL gcat
–1 h–1) at a steam-to-carbon ratio of 2 between 700 and 950 °C. The
mechanochemically synthesized catalysts were benchmarked against those
prepared via incipient wetness impregnation. The most active milled
catalysts achieved a methane conversion rate of ca. 22 mol CH4 gNi
–1 h–1 at
700 °C (83.5% methane conversion for a PtNi/CeO2 mechanochemically
synthesized), outperforming the impregnated counterpart (64% methane
conversion under the same reaction conditions). Notably, increasing
the milling intensity resulted in enhanced catalytic activity, with
milling frequency emerging as the most influential factorcorrelating
with the formation of smaller NiO particles. To elucidate the role
of Pt addition, in situ X-ray absorption near-edge
structure (XANES) and near-ambient pressure X-ray photoelectron spectroscopy
(NAP-XPS) measurements were conducted on the most active milled catalysts
under MSR conditions. NAP-XPS revealed surface segregation of Pt during
MSR, alongside an inhibitory effect on solid carbon deposition, suggesting
the potential for a coke-resistant catalyst. These findings highlight
the power of mechanochemical synthesis in tuning catalyst properties,
offering a scalable and efficient route to high-performance catalysts
for methane reforming and hydrogen production.