Catalysis is the process by which the rate of a chemical reaction (or biological process) is increased by means of the addition of a species known as a catalyst to the reaction. The reaction rate or rate of reaction for a Reactant or product in a particular reaction is intuitively defined as how fast a reaction takes A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called A biological process is a process of a living Organism (either plant or animal What makes a catalyst different from a chemical reagent is that whilst it participates in the reaction, it is not consumed in the reaction. That is, the catalyst may undergo several chemical transformations during the reaction, but at the conclusion of the reaction, the catalyst is regenerated unchanged. As a catalyst is regenerated in a reaction, often only a very small amount is needed to increase the rate of the reaction.
A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst. In Chemistry, activation energy, also called midnight energy, is a term introduced in 1889 by the Swedish scientist Svante Arrhenius, that is defined The lower the activation energy, the faster the rate of the reaction.
Whilst the above reaction is favoured in the sense that reaction products are more stable than the starting material, the reaction is slow. Disproportionation or dismutation is used to describe two particular types of chemical reaction A chemical reaction of the type 2A → A' + A" where Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the This can be seen by the fact that hydrogen peroxide is often available for purchase on the high-street in bottles as a disinfectant. High Street, or the High Street, is a Metonym for the generic name (and frequently the official name of the primary Business street
However, upon the addition of a small amount of manganese dioxide, the hydrogen peroxide undergoes a rapid reaction, which can be readily seen by the effervescence of oxygen. Manganese(IV oxide is the Chemical compound MnO2 commonly called manganese dioxide. Effervescence is the escape of gas from an aqueous solution The term is used to describe the foaming or fizzing that results from a release of gas The manganese dioxide may be recovered unchanged, and re-used indefinitely, and thus is not consumed in the reaction. Accordingly, manganese dioxide catalyses this reaction.
In a more general sense, anything that increases the rate of any process is commonly called a "catalyst" (From the Greek καταλύειν, meaning to annul or to untie or to pick up). Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly For example a matchmaker might be called a catalyst, as he or she brings two people together who otherwise might not meet, with the matchmaker being unaltered by the matching process. Matchmaking is any process of introducing people for the purposes of Dating and Mating, usually in the context of Marriage.
The opposite of a catalyst is an inhibitor which slows the rate of a reaction without itself being consumed. A reaction inhibitor is a substance that decreases the rate of or prevents a Chemical reaction.
The phrase catalysed processes was coined by Jöns Jakob Berzelius in 1836  to describe reactions which are accelerated by substances which remain unchanged after the reaction. Friherre Jöns Jacob Berzelius (20 August 1779 &ndash 7 August 1848 was a Swedish chemist Other early chemists involved in catalysis were Alexander Mitscherlich who in 1831 referred to contact processes and Johann Wolfgang Döbereiner who spoke of contact action and whose lighter based on hydrogen and a platinum sponge became a huge commercial success in the 1820’s. This article is about the chemist Go to Alexander Mitscherlich (Psychology for the psychologist Johann Wolfgang Döbereiner ( December 13, 1780 &ndash March 24, 1849) was a German chemist who is best known for A lighter is a portable device used to create a Flame. It consists of a metal or plastic container filled with lighter fluid (usually Naphtha or liquid Butane Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Humphrey Davy discovered the use of platinum in catalysis. Sir Humphry Davy 1st Baronet FRS MRIA (17 December 1778 &ndash 29 May 1829 was a British Chemist and inventor In the 1880s, Wilhelm Ostwald at Leipzig University started a series of systematic investigations into reactions that were catalyzed by the presence of acids and bases, and found both that chemical reactions occur at finite rates, and that these rates can be used to determine the strengths of acids and bases. Friedrich Wilhelm Ostwald ( Latvian: Vilhelms Ostvalds; September 2, 1853 &ndash April 4, 1932) was a Baltic The University of Leipzig (Universität Leipzig located in Leipzig in the Free State of Saxony, Germany, is one of the oldest universities In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are For this work, Ostwald was awarded the 1909 Nobel Prize in Chemistry. The Nobel Prize in Chemistry (Nobelpriset i kemi is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of Chemistry. 
Catalysts generally react with one or more reactants to form an intermediate that subsequently give the final reaction product, in the process regenerating the catalyst. The following is a typical reaction scheme, where C represents the catalyst, A and B are reactants, and D is the product of the reaction of A and B:
Although the catalyst (C) is consumed by reaction 1, it is subsequently produced by reaction 4, so for the overall reaction:
A catalytic cycle or catalytic mechanism is a reaction mechanism which involves a catalyst. A catalytic cycle in Chemistry is a term for a multistep reaction mechanism that involves a Catalyst. Catalytic cycles are central to any discussion of catalysis, be it in biochemistry, organometallic chemistry, or solid state chemistry. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal.
Often, a so-called sacrificial catalyst is also part of the reaction system with the purpose of regenerating the true catalyst in each cycle. As the name implies the sacrificial catalyst is not regenerated and is instead irreversibly consumed. This sacrificial compound is also known as a stoichiometric catalyst when added in stoichiometric quantities compared to the main reactant. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable Usually the true catalyst is an expensive and complex molecule and added in quantities as small as possible. The stoichiometric catalyst on the other hand should be cheap and abundant. The reaction moves slowly thens curves into the respiratory system.
Catalysts work by providing an (alternative) mechanism involving a different transition state and lower activation energy. In Chemistry, activation energy, also called midnight energy, is a term introduced in 1889 by the Swedish scientist Svante Arrhenius, that is defined The effect of this is that more molecular collisions have the energy needed to reach the transition state. Hence, catalysts can perform reactions that, albeit thermodynamically feasible, would not run without the presence of a catalyst, or perform them much faster, more specific, or at lower temperatures. This can be observed on a Boltzmann distribution and energy profile diagram. WikipediaWikiProject Probability#Standards for a discussion of standards used for probability distribution articles such as this one This means that catalysts reduce the amount of energy needed to start a chemical reaction.
Catalysts cannot make energetically unfavorable reactions possible — they have no effect on the chemical equilibrium of a reaction because the rate of both the forward and the reverse reaction are equally affected (see also thermodynamics). In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " The net free energy change of a reaction is the same whether a catalyst is used or not; the catalyst just makes it easier to activate.
The SI derived unit for measuring the catalytic activity of a catalyst is the katal, which is moles per second. SI derived units are part of the SI system of measurement units and are derived from the seven SI base units They are derived from SI basic units/defined The katal (symbol kat is the SI unit of catalytic activity It is a derived SI unit for expressing quantity values of catalytic activity of Enzymes The degree of activity of a catalyst can also be described by the turn over number (or TON) and the catalytic efficiency by the turn over frequency (TOF). Turnover number has two related meanings In Enzymology, turnover number (also termed kcat) is defined as the maximum number of molecules of substrate The biochemical equivalent is the enzyme unit. The enzyme unit (U is a unit for the amount of a particular Enzyme.
For more information on the efficiency of enzymatic catalysis see the Enzyme#Kinetics section. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins
In autocatalysis, a reaction produces catalysts. A single Chemical reaction is said to have undergone autocatalysis, or be autocatalytic, if the reaction product is itself the Catalyst for that reaction
Catalysts can be either heterogeneous or homogeneous. Heterogeneous is an adjective used to describe an object or system consisting of multiple items having a large number of structural variations Biocatalysts are often seen as a separate group. Biocatalysis can be defined as utilization of natural Catalysts, such as protein Enzymes, to perform chemical transformations on Organic compounds.
Heterogeneous catalysts are present in different phases from the reactants (for example, a solid catalyst in a liquid reaction mixture), whereas homogeneous catalysts are in the same phase (for example, a dissolved catalyst in a liquid reaction mixture). In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties A reagent or reactant is a substance or compound consumed during a Chemical reaction. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called Solvation, commonly called dissolution, is the process of attraction and association of Molecules of a Solvent with molecules or Ions of a
A simple model for heterogeneous catalysis involves the catalyst providing a surface on which the reactants (or substrates) temporarily become adsorbed. Heterogeneous catalysis is a Chemistry term which describes Catalysis where the Catalyst is in a different phase (ie Heterogeneous is an adjective used to describe an object or system consisting of multiple items having a large number of structural variations In Mathematics, specifically in Topology, a surface is a Two-dimensional Manifold. Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the [[bonds between the products and the catalyst are weaker, so the products are released. Different possible mechanisms for reactions on surfaces are known, depending on how the adsorption takes place (Langmuir-Hinshelwood and Eley-Rideal). By reactions on surfaces it is understood reactions in which at least one of the steps of the Reaction mechanism is the Adsorption of one or more reactants By reactions on surfaces it is understood reactions in which at least one of the steps of the Reaction mechanism is the Adsorption of one or more reactants By reactions on surfaces it is understood reactions in which at least one of the steps of the Reaction mechanism is the Adsorption of one or more reactants
For example, in the Haber process to manufacture ammonia, finely divided iron acts as a heterogeneous catalyst. The Haber process, also called the Haber–Bosch process, is the Nitrogen fixation reaction of Nitrogen and Hydrogen, over an iron substrate Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Active sites on the metal allow partial weak bonding to the reactant gases, which are adsorbed onto the metal surface. This page is about the physical properties of gas as a state of matter Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the As a result, the bond within the molecule of a reactant is weakened and the reactant molecules are held in close proximity to each other. In this way the particularly strong triple bond in nitrogen is weakened and the hydrogen and nitrogen molecules are brought closer together than would be the case in the gas phase, so the rate of reaction increases.
Other heterogeneous catalysts include vanadium(V) oxide in the contact process, nickel in the manufacture of margarine, alumina and silica in the cracking of alkanes and platinum, rhodium and palladium in catalytic converters. Vanadium(V oxide ( vanadia) is the Chemical compound with the formula V2O5 The contact process is the current method of producing Sulfuric acid in the high concentrations needed for industrial processes Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Margarine (ˈmɑrdʒərɨn /ˈmɑrdʒəriːn/ or /ˈmɑrgəriːn/ as a generic term can indicate any of a wide range of Butter substitutes The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Alkanes, also known as Paraffins are Chemical compounds that consist only of the elements Carbon (C and Hydrogen (H (i Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Rh redirects here For other uses see Rh (disambiguation Rhodium (ˈroʊdiəm is a Chemical element with the symbol Palladium (pronounced \pəˈleɪdiəm\ is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the A catalytic converter (colloquially "cat" or "catcon" is a device used to reduce the toxicity of emissions from an Internal combustion engine. Mesoporous silicates have found utility in heterogeneous reaction catalysis because their large accessible surface area allows for high catalyst loading. Mesoporous silicates are Silicates with a special morphology Background Porous inorganic solids have found great utility as Catalysts and sorption
In car engines, incomplete combustion of the fuel produces carbon monoxide, which is toxic. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Fuel is any material that is burned or altered in order to obtain energy Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. The electric spark and high temperatures also allow oxygen and nitrogen to react and form nitrogen monoxide and nitrogen dioxide, which are responsible for photochemical smog and acid rain. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] Nitrogen dioxide is the Chemical compound with the formula N[[Oxygen O]]2 Smog is a kind of Air pollution; the word "smog" is a Portmanteau of Smoke and Fog. Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure Catalytic converters reduce such emissions by adsorbing CO and NO onto catalytic surface, where the gases undergo a redox reaction. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Carbon dioxide and nitrogen are desorbed from the surface and emitted as relatively harmless gases:
Many catalysts used in refineries and in petrochemical applications are regenerated and reused multiple times to save costs and energy and to reduce environmental impact from recycling or disposal of spent catalysts. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single
Homogeneous catalysts are in the same phase as the reactants. Homogeneous catalysis is a Chemistry term which describes Catalysis where the Catalyst is in the same phase (ie
In homogeneous catalysis the catalyst is a molecule which facilitates the reaction. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by The catalyst initiates reaction with one or more reactants to form intermediate(s) and in some cases one or more products. Subsequent steps lead to the formation of remaining products and to the regeneration of the catalyst.
Examples of homogeneous catalysts are:
2) Chlorine free radicals in the break down of ozone. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Esterification is the general name for a Chemical reaction in which two reactants (typically an alcohol and an acid form an Ester as the reaction product Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell OZONE is an object oriented Operating system written in the C programming language. These radicals are formed by the action of ultraviolet radiation on chlorofluorocarbons (CFCs). Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Radiation, as in Physics, is Energy in the form of waves or moving Subatomic particles emitted by an atom or other body as it changes from a higher energy The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane They react with ozone to form oxygen molecules and regenerate the catalyst radicals. This process destroys the thin layer of stratospheric ozone. The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930
3) Oxides of nitrogen in the oxidation of sulfur dioxide to sulfur trioxide by dioxygen in the chamber process. The term nitrogen oxide typically refers to any Binary compound of Oxygen and Nitrogen, or to a mixture of such compounds Nitric Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Sulfur trioxide (also spelled sulphur trioxide) is the chemical compound with the formula SO3 The lead chamber process was an industrial process used to produce relatively strong concentrations of Sulfuric acid in large quantities
In nature enzymes are catalysts in metabolism. Biocatalysis can be defined as utilization of natural Catalysts, such as protein Enzymes, to perform chemical transformations on Organic compounds. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. In biochemistry catalysis is also observed with abzymes and ribozymes, deoxyribozymes have also been created in the laboratory. Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as An abzyme (from Antibody and Enzyme) also called catmab (from catalytic monoclonal antibody) is a Monoclonal antibody with A ribozyme (from ribo nucleic acid en' zyme', also called RNA Enzyme or catalytic RNA is an RNA Molecule that catalyzes Deoxyribozymes or DNA enzymes or catalytic DNA, or DNAzymes are DNA molecules with catalytic action
Biocatalysts can be thought of as a mixture of a homogenous and heterogeneous catalyst. This is because the enzyme is in solution itself, but the reaction takes place on the enzyme surface. Several factors affect the activity of enzymes. The most important are:
In the context of electrochemistry, specifically in fuel cell engineering, various metal-rich catalysts are used to promote the efficiency of a half reaction that occurs within the fuel cell. Electrochemistry is a branch of Chemistry that studies Chemical reactions which take place in a Solution at the interface of an electron conductor A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the A half reaction is either the oxidation or reduction reaction component of a Redox reaction. One common type of fuel cell electrocatalyst is based upon tiny nanoparticles of platinum which adorn slightly larger carbon particles. In Nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 When this type of platinum electrocatalyst is in contact with one of the electrodes in a fuel cell, it increases the rate of the redox half reaction in which oxygen gas is reduced to water (or hydroxide or hydrogen peroxide). An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state A half reaction is either the oxidation or reduction reaction component of a Redox reaction. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Chemistry, hydroxide is the most common name for the diatomic Anion OH− consisting of Oxygen and Hydrogen Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water
Catalysis is of paramount importance in the chemical industry. The production of most industrially important chemicals involves catalysis. Two notable commercial processes are the Haber process for ammonia synthesis and the Fischer-Tropsch synthesis. The Haber process, also called the Haber–Bosch process, is the Nitrogen fixation reaction of Nitrogen and Hydrogen, over an iron substrate Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor The Fischer-Tropsch process (or Fischer-Tropsch Synthesis is a catalyzed chemical reaction in which synthesis gas ( Syngas) a mixture of Carbon monoxide Research into catalysis is a major field in applied science, and involves many fields of chemistry, notably in organometallic chemistry, and physics. Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal. Catalysis is important in many aspects of environmental science, from the catalytic converter in automobiles to the alleged causes of the ozone hole. Environmental science is the study of interactions among physical chemical and biological components of the environment. A catalytic converter (colloquially "cat" or "catcon" is a device used to reduce the toxicity of emissions from an Internal combustion engine. Ozone depletion describes two distinct but related observations a slow steady decline of about 4 percent per decade in the total amount of Ozone in Earth's Catalytic, rather than stoichiometric reactions are preferred in environmentally friendly green chemistry due to the reduced amount of waste generated. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry is the Calculation of Quantitative (measurable Green chemistry, also called sustainable chemistry is a chemical philosophy encouraging the design of products and processes that reduce or eliminate the use and generation of hazardous
Estimates are that 90% of all commercially produced chemical products involve catalysts at some stage in the process of their manufacture. 
Manganese dioxide is used in the laboratory to prepare oxygen by the decomposition of hydrogen peroxide to oxygen and water. Manganese(IV oxide is the Chemical compound MnO2 commonly called manganese dioxide. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Water is a common Chemical substance that is essential for the survival of all known forms of Life.
Well-known applications of synthetic catalysts are:
Examples of catalysts that perform specific transformations on functional groups:
These given examples show that different catalysts perform other transformations on the same functional groups, where the reaction would not proceed, proceed very slowly, or proceed in an unselective manner without the presence of the catalyst.
The most common catalyst is the proton. Many transition metals and transition metal complexes are used in catalysis as well. In Chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings It commonly refers to any element in The term complex in Chemistry is usually used to describe molecules or ensembles formed by the combination of Ligands and metal Ions.
While transition metal catalysts are well established, a new trend is toward organocatalysis which use comparatively simple organic molecules as catalysts. In Organic chemistry, the term Organocatalysis (a Concatenation of the terms "organic" and "catalyst" refers to a form of Catalysis While typically, catalyst loading is much higher than transition metal-based catalysts, the catalysts are usually commercially available in bulk, helping to reduce costs drastically. Organocatalysts of the "new generation" are competitive to traditional metal-containing catalysts and are owing to low product inhibition applicable in substoichiometric quantities. In Organic chemistry, the term Organocatalysis (a Concatenation of the terms "organic" and "catalyst" refers to a form of Catalysis The chemical character of organocatalysts offers new and attractive perspectives and advantages to synthesis chemists.
In 2005, Catalytic processes generated about $900 billion in products worldwide. (pdf)