What is a cataylst
By catalyst is meant a substance or element, either simple or compound, which plays a role accelerator in a chemical reaction determined, shortening that occurs without altering at all the end product of the same without either losing their own mass the process, which does happen in the reagents.
This process of chemical acceleration is called catalysis. And to the elements or substances that inhibit catalysis, they are known as inhibitors . Each chemical reaction has a suitable catalyst, which can accelerate (positive catalysis) or slow down (negative catalysis) its process.
The research in catalysis and production of catalytic agents is a prolific field of the chemical and biological industry , since they allow to accelerate reactions or to maximize the quantity of product obtained, simply with the opportune addition of the suitable catalyst.
Examples of catalyst (and its function)
- Enzymes . Substances segregated biologically and naturally by the body of living beings, enzymes play a very important catalytic role, since they accelerate vital chemical processes that, if occurring on their own, would require temperatures that are often incompatible with life. Pepsin and trypsin, for example, are involved in the decomposition of meats, thus accelerating a digestion that would otherwise take much more time and effort.
- Temperature . Some chemical reactions can be accelerated without altering their products with the only increase in the temperature of the medium. Thus, for example, raising the water temperature of the paste allows it to soften more quickly, acting as an extreme catalyst.
- UV light . Ultraviolet light, together with a catalyst, allows photocatalysis: the acceleration of a chemical reaction by a catalyst activated by the ultraviolet light energy. Ozone and oxides of metals in transition are common photocatalysts.
- Palladium catalysts . Incorporated into automotive systems that use unleaded gasoline, these devices contain palladium or platinum in small particles in a container that adheres to car exhaust. These metals act as catalysts in the process of attenuation of carbon monoxide and other toxic gases of combustion, allowing to reduce them to water vapor or other less dangerous substances in record time.
- Aluminum Chloride . This catalyst is used in the petrochemical industry to obtain synthetic resins or lubricating substances, without altering the delicate nature of the hydrocarbons in question, since it has acid and basic properties at the same time (it is amphoteric).
- Derivatives of fluorine . They accelerate the decomposition of ozone (O 3 ? O + O 2 ), which is usually a fairly slow reaction. There is the problem of aerosols and refrigerants that release CFCs into the atmosphere: they dilute the ozone layer.
- Acidic substances . The protons released by most acidic substances can play the role of catalysts in certain chemical reactions, such as hydrolysis (separation of hydrogen) from esters (inorganic petroleum derivatives).
- Zinc . It is a common catalyst in the constitution of cycloalkanes ( saturated hydrocarbons ) used in perfumery, the oil industry and others.
- Magnesium dioxide (MnO 2 ). This compound is a frequent catalyst to accelerate the decomposition of Hydrogen Peroxide or hydrogen peroxide (2H 2 O 2 ? 2H 2 O + O 2 ).
- Iron . This metal is used as a catalyst in the Haber-Bosch process to obtain ammonia from hydrogen and nitrogen.
- Vanadium pentoxide (V 2 O 5 ) . A highly toxic compound that, when heated, loses oxygen reversibly. Therefore, it is used as a catalyst in the production of sulfuric acid from sulfur dioxide (SO 2 ).
- Titanium . Mixed with aluminum, it is used in the polymerization process of Ziegler-Natta to accelerate the production of high density polyethylene (HDPE), used to manufacture containers and plastic bottle lids.
- Nickel . Finely divided, it is used in the hydrogenation of vegetable oils through which margarine is obtained: unsaturated fats become saturated by the bombardment of hydrogen and this metal accelerates this process.
- Silicon dioxide or silica (SO 2 ) . It is one of the catalysts most used in the process of catalytic cracking of oil, added to the high pressure and temperatures. The cracking is getting simpler substances from a complex hydrocarbon.
- Cobalt (Co) and Molybdenum (Mo) . Substances used on albumin in the process of catalytic reforming of oil, in which the heavy naphtha is stripped of sulfur and nitrogen, to increase its octane rating.
- Potassium permanganate (KMnO 4 ) . It is used as a catalyst for the chemical reaction that transforms alkenes (unsaturated hydrocarbons or olefins) into diols.
- Platinum . This metal is used as a catalyst in certain reactions for obtaining benzene derivatives, such as cyclohexane, which is indispensable in the manufacture of nylon.
- Gold . Recent research shows the effectiveness of gold as a nanocatalyst, that is, when it is found in atomic groupings of between eight and two dozen atoms .
- Citric acid . The acid contained by lemon or other citrus fruits allows to slow down (negative catalysis) the oxidation process of organic matter. This can be verified with a piece of apple; It is a popular experiment in school education.
- Silver . Polycrystalline silver and nanoporous silver in electrocatalysis experiments are effective accelerators of carbon dioxide (CO 2 ) reduction processes , allowing the efficient obtaining of useful chemical products