Question

dhomogeneous and heterogeneous catalysis application of catalysts enzymatic catalysis ans its features

Answer 1

The Homogeneous and Heterogeneous catalysis : -

The Homogeneous catalysis is a catalysis in a solution by a soluble catalyst. The homogeneous catalysis refers to catalytic reactions where the catalyst is in the same phase as the reactants. The homogeneous catalysis applies to reactions in the gas phase and even in solids. The heterogeneous catalysis is the alternative to homogeneous catalysis, where as the catalysis occurs at the interface of two phases, typically gas-solid. This term is used almost exclusively to describe solutions and often implies catalysis by organometallic compounds.

So, the homogeneous catalysis using transition metal complexes is an area of research that has grown enormously in recent years. So many remarkable catalytic discoveries have been reported by researchers both in industry and in academia.

The Advantages of homogeneous catalysis is :-

• The Homogeneous catalysts are effective at being highly selective towards producing the desired product.
• The reactants can easily access the homogeneous catalyst because it is in solution already. This promotes high catalytic activity.

The Disadvantages of homogeneous catalysis is :-

• A catalyst capable of dissolving in solution will need to be separated later if it is to be recycled for re-usage.

The Heterogeneous catalysis is the type of catalysis, where the phase of the catalyst differs from the phase of the reactants. So,this contrasts with homogeneous catalysis where the reactants and catalyst exist in the same phase. The Phase distinguishes between not only solid, liquid, and gas components, but also the immiscible mixtures like oil and water, or anywhere an interface is present. The catalysts are useful because they increase the rate of a reactio^] without themselves being consumed and are therefore reusable.

So, The Heterogeneous catalysis are typically involves solid phase catalysts and the gas phase reactants. in this case, there is a cycle of molecular adsorption, reaction, and desorption occurring at the catalyst surface. So, the thermodynamics, mass transfer, and heat transfer influence the rate of reaction.

Application of catalysts:-

The Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which is not consumed in the catalyzed reaction and can continue to act repeatedly. Because of this, the only very small amounts of catalyst are required to alter the reaction rate in principle.

So, in general,the chemical reactions occur faster in the presence of a catalyst because the catalyst provides an alternative reaction pathway with a lower activation energy than the non-catalyzed mechanism. In the catalyzed mechanisms, the catalyst usually reacts to form a temporary intermediate, which then regenerates the original catalyst in a cyclic process. A substance which provides a mechanism with a higher activation energy does not decrease the rate because the reaction can still occur by the non-catalyzed route. And an added substance which does reduce the reaction rate is not considered a catalyst ,but a reaction inhibitor .

The catalysts may be classified as either homogeneous or heterogeneous. A homogeneous catalyst is one whose molecules are dispersed in the same phase as the reactant's molecules. And the heterogeneous catalyst is one whose molecules are not in the same phase as the reactant's, which are typically gases or liquids that are adsorbed onto the surface of the solid catalyst. The enzymes and other the biocatalysts are often considered as a third category.

Enzymatic catalysis:-

The catalysis is a phenolmenon in which the rate of the reaction is altered, and the substance used to accelerate remains unchanged regarding quantity and chemical properties. The substance used to change the speed of the reaction is called a catalyst. So, the enzymes are a type of catalysts which are responsible for increasing the rate of reaction in plants and animals. The catalysis in which enzymes act as a catalyst is called enzymatic catalysis.

So, the enzymes are complex compounds which are made up of nitrogen. The animals and plants produce these compounds. The enzymes are proteins which have high molecular mass and form a heterogeneous mixture when dissolved in water. These proteins act very efficiently and are responsible for various reactions which occur in the body of living beings. These proteins can also be called as biochemical catalysts and the catalysis as biochemical catalysis

Features :-

• The effectiveness of a catalyst is maximum at its optimum temperature. The activity of the biochemical catalysts declines at either side of the optimum temperature.
• Biochemical catalysis is dependent upon the pH of the solution. A catalyst works best at an optimum pH which ranges between 5-7 PH values.
• A single molecule of this catalysis can transform a million molecules of the reactant per second. Hence it is highly efficient.
• These biochemical catalysts are unique in nature i.e. the same catalyst cannot be used in more than one reaction.