Page 95 - Academic Press Encyclopedia of Physical Science and Technology 3rd Chemical Engineering

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Encyclopedia of Physical Science and Technology EN002C-86 May 17, 2001 20:36

Catalysis, Industrial 493

duetocatalystchangesinclude:(1)reducedfeedstockcon- already. Implementation of these proposals will increase
sumption or cost; (2) lower energy consumption; (3) in- environmental catalyst markets.
creased by-product credits or reduced by-product debits;
(4) reduced capital investment; and (5) increased stream C. Standard of Living
factor.
Process improvements can also result in products of Industrial catalysts have made it possible to utilize and en-
higher quality or in a safer, more environmentally accept- joy many new products in the areas of plastics, transporta-
able commercial operation. Catalysts of higher activity tion, clothing, detergents, food supply, and construction.
can reduce the required operating temperature or pressure The production of most polymers involves catalysis either
in a process unit and save energy. in polymerization or in monomer synthesis. Improved fu-
els, tires, and construction materials have revolutionized
the transportation industry in this century. Synthetic fibers
B. Environment are widely used in clothing and carpets. Biodegradable de-
Catalysts help customers comply cost-effectively with tergents are available for inexpensive cleaning. Fertilizers,
clean-air regulations. Hydrocarbons, carbon monoxide, pesticides, and herbicides have been used to increase crop
and nitrogen oxides can be removed using supported pre- yields to feed a growing world population.
cious metal catalysts. Organic sulfur compounds are con-
verted to H 2 S using nickel/molybdenum or cobalt/molyb- II. HISTORY
denum on alumina catalysts. Sulfur can be recovered in
a Claus process unit. The Claus catalytic converter is the
Catalysis has made possible the change in the chemical
heart of a sulfur recovery plant.
process industry from feedstocks of coal and acetylene,
H 2 S + 3/2O 2 → SO 2 + H 2 O (1) to ethylene. Activation of alkanes is now a major research
topic. German industrial scientists led in the coal- and
2H 2 S + SO 2 → 3/nS n + 2H 2 O (2)
acetylene-based chemical industry developments. Many
The first reaction takes place at high temperature in a of the chemical products were for the dyestuffs industry.
furnace fed with a sour gas and air mixture. The second re- Multicomponent catalysts were first studied after 1900
action is catalyzed by alumina. Operational temperatures at Badische Anilin-und Soda-Fabrik (BASF). This led
◦
are ∼330 C. to the discovery of a magnetite promoted with alumina
The most widely known pollution control catalysts are and alkali ammonia synthesis catalyst in 1908 by Haber.
those for auto emission control. Automotive catalysts can Bosch and BASF developed a methanol synthesis cata-
be of two types—monoliths and pellets. Monoliths now lyst composed of the mixed oxides of zinc, chromium,
dominate the market. Pollution control catalysts are also and potassium in 1923. Fischer and Tropsch made syn-
used to control diesel emissions. thetic hydrocarbons from synthesis gas in 1927. In the
Automotive emission control is a major catalyst mar- United States, Union Carbide made chemicals initially
ket segment. These catalysts perform three functions: (1) from acetylene. They became interested in ethylene and
oxidize carbon monoxide to carbon dioxide; (2) oxidize in 1926 began production of cellosolve based on ethylene.
hydrocarbons to carbon dioxide and water; and (3) re- In 1927 Shell Chemical began steps to produce chemicals
duce nitrogen oxides to nitrogen. The oxidation reactions from petroleum feedstocks. Initially they focused on am-
use platinum and palladium as the active metal. Rhodium monia, propylene, and solvents. Standard Oil Company
is the metal of choice for the reduction reaction. These (NJ) about the same time decided to study the application
three-way catalysts meet the current standards of 0.41 g of chemical engineering to the upgrading of petroleum
hydrocarbon per mile, 3.4 g carbon monoxide per mile, fractions. This led them into hydrogenation, olefins, and
and 0.4 g nitrogen oxides per mile. aromatics catalysis research. Dow Chemical led in the de-
New proposed “Tier 2” emission standards proposed for velopment of chlorine and bromine chemistry using nat-
introduction in the 2004 model year would apply to sport ural gas as the energy source.
utility vehicles, minivans, and pickup trucks and make There is a continuing stream of new-generation cata-
them meet the same standards as passenger cars. It has lysts for refining, polyolefin formation, oxychlorination,
also been proposed to lower the sulfur level in gasoline hydrogenation, and other catalyst applications. Some of
to 30 PPM from the current average level of 300 PPM the names and areas of contribution in industrial catalysis
by 2004. The Euro IV limits proposed for 2005 are sat- are given in Table II. Highlights of industrial application
isfied by technology from at least one catalyst supplier of catalysts are given in Table III.