Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

Antonios Tribalis,Christos Kordulis,Alexis Lycourghiotis,Spyridon Ladas,George Panagiotou,Kyriakos Bourikas,Stella Kennou,Labrini Sygellou

doi:10.3390/catal6010011

Abstract

Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba)- and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior.

Highlights

PEM fuel cell technology promises to be an efficient and clean alternative with respect to fuel combustion for primary power generation in stationary and mobile source applications
Steam reforming Ni-based catalysts are the most popular. These catalysts are cost effective and commercially available, they have a number of drawbacks when considered for fuel cell applications
The catalytic performance of the catalysts studied was evaluated in a fixed bed micro-reactor for the steam reforming of hexadecane and hexadecane doped with dibenzothiophene corresponding to surrogate commercial diesel with 10 ppm sulphur

Summary

Introduction

PEM (proton-exchange membrane) fuel cell technology promises to be an efficient and clean alternative with respect to fuel combustion for primary power generation in stationary and mobile source applications. The process of converting petroleum fuels to hydrogen-rich gas products that have been developed in the past generally fall into one of the following classes—steam reforming (SR), partial oxidation (POX), autothermal reforming (ATR), dry reforming (DR) or a combination of two or more of the above. Despite their advantages, each of these processes has drawbacks with respect to design, fuel, and operating temperature [3]. Steam reforming Ni-based catalysts are the most popular These catalysts are cost effective and commercially available, they have a number of drawbacks when considered for fuel cell applications. We attempted to gain insight concerning the influence of support modification on carbon deposition and sulfur poisoning during steam reforming

Physicochemical Characteristics of the Supports

Physicochemical Characteristics of the Ni-Catalysts

Catalyst Evaluation

Experimental Section

Conclusions