CATALYST
- CAS No.
- Chemical Name:
- CATALYST
- Synonyms
- CATALYST;JB-4 CATALYST;JB-4 PLUS CATALYST;NAFION SUPER ACID CATALYST
- CBNumber:
- CB5239939
- Molecular Formula:
- Molecular Weight:
- 0
- MDL Number:
- MFCD00282831
- MOL File:
- Mol file
CATALYST Chemical Properties,Uses,Production
Definition
A substance that alters
the rate of a chemical reaction without
itself being changed chemically in the reaction.
The catalyst can, however, undergo
physical change; for example, large lumps
of catalyst can, without loss in mass, be
converted into a powder. Small amounts of
catalyst are often sufficient to increase the
rate of reaction considerably. A positive
catalyst increases the rate of a reaction and
a negative catalyst reduces it. Homogeneous
catalysts are those that act in the
same phase as the reactants (i.e. in gaseous
and liquid systems). For example, nitrogen(
II) oxide gas will catalyze the reaction
between sulfur(IV) oxide and oxygen in the
gaseous phase. Heterogeneous catalysts act
in a different phase from the reactants. For
example, finely divided nickel (a solid) will
catalyze the hydrogenation of oil (liquid).
The function of a catalyst is to provide
a new pathway for which the rate-determining
step has a lower activation energy
than in the uncatalyzed reaction. A catalyst
does not change the products in an equilibrium
reaction and their concentration is
identical to that in the uncatalyzed reaction;
i.e. the position of the equilibrium remains
unchanged. The catalyst simply
increases the rate at which equilibrium is
attained.
In autocatalysis, one of the products of
the reaction itself acts as a catalyst. In this
type of reaction the reaction rate increases
with time to a maximum and finally slows
down. For example, in the hydrolysis of
ethyl ethanoate, the ethanoic acid produced
catalyzes the reaction.
Agricultural Uses
A catalyst is a substance which, in small quantities,
facilitates a reaction or favorably alters the rate of a
chemical reaction, without itself undergoing any
permanent chemical change. This phenomenon is called
catalysis. Acid-based catalysis is an important type of
catalysis.
Catalysts that have the same phase as the reactants are
known as homogeneous catalysts while those having a
different phase are called heterogeneous catalysts.
Generally, a catalyst that increases the reaction rate is
known as a positive catalyst while one that slows down
the rate is known as a negative catalyst, retardant or
inhibitor.
Some examples of catalysts and their roles are as
follows: (i) Protein catalysts, called enzymes, speed up
many chemical reactions in living organisms. These play
a key role in all metabolic or biological processes and in
some manufacturing processes, such as the fermentation
industry. (ii) Catalytic converters, in automobiles,
employ a mixed oxide bed over which the exhaust gases
pass after they are mixed with additional air. These
catalysts promote oxidation of carbon monoxide and
hydrocarbons to carbon dioxide and water.
Catalysts may be inorganic, organic or complexes of
organic groups and metal halides. (Zeigler-Natta
cataIysts). They may be gases, liquids or solids. In some
cases, their action is undesirable and destructive, as in the
oxidation of iron to iron oxide, which is catalyzed by
water vapor (rusting). The life of an industrial catalyst
varies from 1000 to 10,000 hours, after which it must be
replaced.
Catalysts are highly specific in their action and
application and very essential for many industrial
chemical reactions, as in petroleum refining and organic
syntheses. The activity of a solid catalyst is centerd in a
small fraction of its surface; adding promoters increases
the surface area by increasing the porosity or the number
of active points. Substances that act as poisons clog and
weaken the catalyst surface, thus decreasing the catalytic
activity.
CATALYST Preparation Products And Raw materials
Raw materials
Preparation Products
| Supplier | Tel | Country | ProdList | Advantage | |
|---|---|---|---|---|---|
| Modi Chem | -- | India | 2 | 58 | |
| ChemEngg Research Private Limited | -- | India | 4 | 58 | |
| DuPont Specialty Colorants & Additives | -- | United States | 1186 | 87 | |
| HONEST JOY HOLDINGS LIMITED | -- | sales@honestjoy.cn | United States | 6702 | 54 |
| Electron Microscopy Sciences | -- | sgkcck@aol.com | United States | 672 | 81 |
| Polysciences, Inc. | -- | info@polysciences.com | United States | 1119 | 81 |
| Supplier | Advantage |
|---|---|
| Modi Chem | 58 |
| ChemEngg Research Private Limited | 58 |
| DuPont Specialty Colorants & Additives | 87 |
| HONEST JOY HOLDINGS LIMITED | 54 |
| Electron Microscopy Sciences | 81 |
| Polysciences, Inc. | 81 |