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3.2.2. Catalyst
Catalysts used are bimetallic platinum - rhenium (Pt/Re) or platinum – tin (Pt/Sn) catalysts.
Pt/Re is mostly used for semi-regenerative process and Pt/Sn for circulating bed process.
Reforming catalysts activate many different reactions. However, they are very sensitive to
impurities and require the feed pre-treatment. Another drawback is that these catalysts
produce coke at a non negligible speed. This speed can nevertheless
be reduced with high
pressure of hydrogen.
3.3. Products characteristics
Catalytic reforming generates three main products: reformate stream,
hydrogen rich gas
stream and LPG stream. There is also a by-product which is a fuel gas stream from the LPG
absorber.
3.4. Reaction section
Reactions occurring in catalytic reforming are numerous. Desired reactions are:
- Dehydrogenation
+ 3 H
2
- Isomerization/dehydrogenation
+ 3 H
2
- Parrafins isomerization
n
-C
7
H
16
i
-C
7
H
16
- Dehydrocyclization
n
-C
7
H
16
+ 4 H
2
Other parasite reactions are promoted with the catalyst. These
reactions are dismutation,
alkylation, hydrocracking, hydrodealkylation and coking.
Different technologies exist for catalytic reforming. These differences concern mainly the
reactor type: the catalytic bed can be either fixed or mobile.
With fixed bed, two processes
exist: semi-regenerative or cyclic. With a mobile bed, a continuous
process is proposed by
Axens. Simplified process schemes and basic information are given below.