| 1. |
Absorption |
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The taking up of a gas or vapour (absorbate) by a liquid or solid (absorbent). The substance taken up is distributed throughout the body of the absorbent. |
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| 2. |
Activated Base Metal Catalyst (ABMC) |
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A porous skeletal metal catalyst used for hydrogenation reactions. It is prepared by leaching alloys containing aluminium and a base metal (typically Ni, Cu or Co) with caustic (eg NaOH) to remove most of the aluminium. |
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| 3. |
Activated carbon |
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An amorphous form of carbon with high porosity and a large adsorption capacity for many gases, vapours and colloidal solids. It is one of the most common types of support used in the manufacture of supported metal catalysts. |
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| 4. |
Activation (of catalysts) |
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A step during catalyst manufacture, in which the catalyst is converted into its active form by physical or chemical treatment. For example, oxidic catalysts are often activated by calcination in air, and metal catalysts by gas-phase reduction using, for instance, hydrogen or by liquid-phase reduction using reducing agents such as hydrazine. |
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| 5. |
Activity (catalytic) |
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Refers to the rate at which the catalyst converts the starting material. |
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| 6. |
Adiabatic |
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Describes a process occurring in a thermally insulated system, so that there is no transfer of heat to or from the surroundings. |
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| 7. |
Adsorption |
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An increase in the concentration of a dissolved substance at the interface of a condensed and a liquid or gaseous phase due to the operation of surface forces. There are two adsorption processes: physisorption and chemisorption. |
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| 8. |
Aggregation |
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Describes the tendency of primary particles to form assemblages exhibiting an identifiable collective behaviour or common characteristics, such as the chemical nature of the aggregated primary particles, the texture of the aggregates or resistance to mechanical separation upon grinding. |
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| 9. |
Alumina (activated) |
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A highly porous form of aluminium oxide with an absorptive capacity for moisture and odours. It is used in the petroleum industry, in water purification and as a catalyst support. |
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| 10. |
Alumina (aluminium oxide) |
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A compound used as a catalyst support. It exists as a white powder in many modifications, each with different properties. |
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