ABSTRACT
Throughout the previous chapters there have been several references or acknowledgments to a
very important property of petroleum and petroleum products. And that is the hydrogen
content or the use of hydrogen during refining in hydrotreating processes, such as desulfur-
ization (Chapter 20) and in hydroconversion processes, such as hydrocracking (Chapter 21).
Although the hydrogen recycle gas may contain up to 40% by volume of other gases (usually
hydrocarbons), hydrotreater catalyst life is a strong function of hydrogen partial pressure.
Optimum hydrogen purity at the reactor inlet extends catalyst life by maintaining desulphur-
ization kinetics at lower operating temperatures and reducing carbon laydown. Typical purity
increases resulting from hydrogen purification equipment and increased hydrogen sulfide
removal as well as tuning hydrogen circulation and purge rates, extending catalyst life up to
about 25%.
