Activated Carbon Catalyst Support
One of important application of Activated
Carbon is as catalyst support and promoter, also can be directly as catalyst.
As a support, mainly used to support catalyst, lets catalyst load on its
surface and makes it possesses certain physical and chemical property, support
itself generally does not have catalytic activity. Common supports include activated alumina,
activated carbon, molecular sieve, clay, honeycomb ceramics, monox, kaolin,
diatomite, etc. Usually used “active component-support name” to indicate
supported catalyst composition, for example, Pd-activated carbon catalyst for
hydrogenation, Pt-honeycomb ceramics catalyst for automotive exhaust
purification.
Activated
carbon impregnated with metal salts solution can make the catalyst load on the
surface of activated carbon, activated carbon’s surface oxidation, acidic
functional groups, electron accepting ability, free radicals, pore structure,
chemical structure can affect the performance of the active component.
Activated
carbon has the irregular graphite structure, in which includes traces of ash,
nitrogen, sulfur, hydrogen, oxygen and so on, these ingredients can have the
influence to the catalyst performance; Ash is an important indicator of support
activated carbon; C-O structure on the surface of activated carbon will affect
oxidizing reaction, halogenating response, adsorption performance and
electricity performance.
Due
to Yuanying activated carbon has abundant pore
structure, special electronic properties, easy to regulate surface groups, high
specific surface area, strong acid-resistant, alkali-resistant and
heat-resistant properties, when used as a catalyst support, the
precursor of active component is fully dispersed. Activated carbon itself has
catalytic activity, interaction with active component can affect the activity
and selectivity of the catalyst, and can save the quantity of active substance.
Compare with using metal alone, when activated carbon supports trace amounts of
transition metals, hydrogen shows obvious reversible adsorption phenomenon,
this called overflow spillover phenomenon.
Activated
carbon includes powder and granule, in the process of gas-solid reaction, all
used granule activated carbon as catalyst support. Although activated carbon’s
specific surface area is very high, but compare with activated alumina support,
honeycomb ceramics support and molecular sieve support, its mechanical strength
is lower. Therefore, in the production process, commonly activated carbon’s
strength is controlled above 95%.
Precious
metal catalyst includes Pd catalyst, Ru catalyst, rhodium catalyst, Pt
catalyst, etc. As precious metal support, activated carbon shape can be powder,
cylinder, sphere and granule.
Application
(1)
Isomerization: Ni-Carbon catalyst can let plant oil isomerization (cottonseed
oil, linseed oil, rapeseed oil, etc.), from non-conjugated oil into conjugated
forms;
(2)
Hydrogenation, dehydrogenation and dehydrogenation of aromatization,
cyclization and isomerization: Pd-activated carbon catalyst or Pt-activated
carbon catalyst can play this catalytic role;
(3)
Low pressure polymerization of olefins: Activated carbon loads on Ni, Co or
their oxide can let olefin polymerization;
(4)
Synthetic fibre: In the production of vinylon, activated carbon impregnated
zinc acetate can let acetylene and acetic acid synthetise vinyl acetate;
(5)
Gum Rosin reprocessing: Activated carbon loads on Pd can produce hydrogenated
rosin and disproportionated rosin;
(6)
Synthesis of vinyl chloride: Activated carbon loads on mercuric chloride can
let acetylene and hydrogen chloride synthetise vinyl chloride.
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