The Impact of Catalytic Materials on Fuel Reformulation

The impact of catalytic materials on fuel reformulation

Stefano Rossini

Snamprogetti, S. Donato Milanese, Italy

Abstract

Fuel reformulation has been seeded by the growing consciousness of the potential damages mankind was causing to the

ecosystem and to itself. Fuel reformulation means that fuels are defined on a chemical composition base with additional

engine-technology related standards rather than on pure performance bases. These standards, which are getting more and

more stringent, can be met by different leverages, mainly catalysts and processes operating conditions.

This survey reviews the contribution of catalytic materials to the production of cleaner fuel components through some

significant examples selected from scientific and technical literature. Having described the trends in automotive fuels quality,

production of gasoline and diesel pool components is discussed relating the required properties to the material active site

configuration, i.e. acidity/basicity, structural parameters, physical constraints. While distinctions are made between pathways

leading to gasoline and those leading to diesel, sulfur removal is faced on a more generalized approach.

© 2002 Elsevier Science B.V. All rights reserved.

Keywords: Catalytic materials; Fuel reformulation; Sulfur; Reformulated gasoline; Reformulated diesel

1. Introduction

As a consequence of the growing awareness of

mankind to the potential damage to the earth's ecosystem,

a fuel revolution is taking place: "reformulated

fuels" are defined on a chemical composition base

with additional performance standards rather than on

a behavior base.

The energy history has experienced the introduction

of fossil fuels in the last couple of centuries causing

a continuously growing release of contaminants

to the atmosphere. Their nature and effects are different

and we can divide them into toxic and non-toxic

to the human health and into "short range" and "long

range" environmental effects. Table 1 gives rough and

simplified indications, taking into account the major

effect.

E-mail address: stefano.rossini@snamprogetti.eni.it (S. Rossini).

Many excellent papers have been published on

how refinery technologies can contribute to meet the

specifications for reformulated fuels [1]. Therefore

this survey will focus on the specific contribution of

catalytic materials, keeping in mind that the operating

conditions of the main units (FCC, reformer) can

significantly contribute to the goal.

2. Trends in automotive fuels quality

The challenge for the internal combustion engine is

the reduction of pollutant exhaust coupled with a lower

CO2 emission. A higher quality of fuels can reduce

the exhaust either directly through an improved combustion

or indirectly by enabling the use improved exhaust

abatement technologies. Several programs have

contributed to the definition of fuels standards and

some of them are still in progress: in Europe the European

Auto-Oil Program I and II (EPEFE), "Clean Air

0920-5861/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.

PII: S0920-5861(02)00386-3

468 S. Rossini / Catalysis Today 77 (2003) 467-484

Table 1

Main exhaust gases contaminants and their effects

Species Toxic Non-toxic Short

range

Long

range

Effect

CO2 X X Greenhouse

CO X X Lethal effects

NOx X X X O3 depletion

contribution

Olefins X X O3 depletion

SOx X X Acid rains

Benzene X X Carcinogenic

For Europe" (CAFE) and "European Climate Change

Program" (ECCP); in the US, the US Air Quality

Improvement Research Program (AQIRP), Phase I

and II.

The standards fixed by the European Union are reported

in Table 2; the last column shows the baseline

before 2000.

From January 1998, the requirements of the US

reformulated gasoline are evaluated via a set of

equations--Model I and its evolution, the Complex

Model--which predict emissions from fuel characteristics.

However, limits have been set for benzene (1%,

max) and oxygen (2 wt.%, min). Recently, California

banned methylterbutil