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Zeolites occur in nature and have been known for almost 250 years
as alumino silicate minerals. Examples are clinoptilolite,
mordenite, offretite, ferrierite, erionite and chabazite. Today,
most of these and many other zeolites are of great interest in
heterogeneous catalysis, yet their naturally occurring forms are of
limited value as catalysts because nature has not optimized their
properties for catalytic applications and the naturally occurring
zeolites almost always contain undesired impurity phases. It was
only with the advent of synthetic zeolites in the period from about
1948 to 1959 (thanks to the pioneering work of R. M. Barrer and R.
M. Milton) that this class of porous materials began to playa role
in catalysis. A landmark event was the introduction of synthetic
faujasites (zeolite X at first, zeolite Y slightly later) as
catalysts in fluid catalytic cracking (FCC) of heavy petroleum
distillates in 1962, one of the most important chemical processes
with a worldwide capacity of the order of 500 million t/a. Compared
to the previously used amorphous silica-alumina catalysts, the
zeolites were not only orders of magnitude more active, which
enabled drastic process engineering improvements to be made, but
they also brought about a significant increase in the yield of the
target product, viz. motor gasoline. With the huge FCC capacity
worldwide, the added value of this yield enhancement is of the
order of 10 billion US $ per year."
Zeolites occur in nature and have been known for almost 250 years
as alumino silicate minerals. Examples are clinoptilolite,
mordenite, offretite, ferrierite, erionite and chabazite. Today,
most of these and many other zeolites are of great interest in
heterogeneous catalysis, yet their naturally occurring forms are of
limited value as catalysts because nature has not optimized their
properties for catalytic applications and the naturally occurring
zeolites almost always contain undesired impurity phases. It was
only with the advent of synthetic zeolites in the period from about
1948 to 1959 (thanks to the pioneering work of R. M. Barrer and R.
M. Milton) that this class of porous materials began to playa role
in catalysis. A landmark event was the introduction of synthetic
faujasites (zeolite X at first, zeolite Y slightly later) as
catalysts in fluid catalytic cracking (FCC) of heavy petroleum
distillates in 1962, one of the most important chemical processes
with a worldwide capacity of the order of 500 million t/a. Compared
to the previously used amorphous silica-alumina catalysts, the
zeolites were not only orders of magnitude more active, which
enabled drastic process engineering improvements to be made, but
they also brought about a significant increase in the yield of the
target product, viz. motor gasoline. With the huge FCC capacity
worldwide, the added value of this yield enhancement is of the
order of 10 billion US $ per year."
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