Bimetallic Nanoparticles as a Model System for an Industrial NiMo Catalyst.

Sara Blomberg,Niclas Johansson,Esko Kokkonen,Christian Hulteberg,Sara M Franzén,Maria E Messing,Linnéa Kollberg,Calle Preger,Jenny Rissler

doi:10.3390/ma12223727

Abstract

An in-depth understanding of the reaction mechanism is required for the further development of Mo-based catalysts for biobased feedstocks. However, fundamental studies of industrial catalysts are challenging, and simplified systems are often used without direct comparison to their industrial counterparts. Here, we report on size-selected bimetallic NiMo nanoparticles as a candidate for a model catalyst that is directly compared to the industrial system to evaluate their industrial relevance. Both the nanoparticles and industrial supported NiMo catalysts were characterized using surface- and bulk-sensitive techniques. We found that the active Ni and Mo metals in the industrial catalyst are well dispersed and well mixed on the support, and that the interaction between Ni and Mo promotes the reduction of the Mo oxide. We successfully produced 25 nm NiMo alloyed nanoparticles with a narrow size distribution. Characterization of the nanoparticles showed that they have a metallic core with a native oxide shell with a high potential for use as a model system for fundamental studies of hydrotreating catalysts for biobased feedstocks.

Highlights

The depletion of fossil fuels and the effects of global warming underline the importance of finding alternative fuels in the near future
Our findings demonstrate that the spark discharge method generates alloyed NiMo nanoparticles nanoparticles with a metallic core surrounded by an oxide shell
The oxidation state of the metals in the surface of the nanoparticles determined by X-ray photoelectron spectroscopy (XPS) is in good agreement with the oxidation states found for the metals in the industrial catalyst

Summary

Introduction

The depletion of fossil fuels and the effects of global warming underline the importance of finding alternative fuels in the near future. Renewable feedstocks have been the subject of considerable attention in recent decades, and a large number of potential renewable resources, such as lignin, have been studied. Lignin is the second most abundant natural polymer in nature and is believed to have considerable potential as a value-added feedstock [1,2]. Mo-based catalysts have played an essential role in the hydrotreating reaction in the petrochemical industry for several decades and have, been studied in in-depth [7], we still do not have a complete understanding of the active site of the bimetallic catalyst. It has been suggested that Ni or Co promote the activity of Mo catalysts by affecting the reactivity of the Mo atoms, but fundamental studies on an atomic level are required to obtain detailed information on the impact of promotors in Mo catalysts

Methods

Results

Discussion

Conclusion