Heterogeneous catalyst cracking products

Many catalysts used in industry are heterogeneous, e.g. zeolites in the cracking of heavy crude oil. The actual reaction takes place on the surface of the solid, with the substrates and products being in the gas or liquid phase, depending on the type of reaction and reactor being used. Many involve a metal on some kind of support e.g. Pd on charcoal, Ni on alumina. The surface area and porosity of heterogeneous catalysts are important in determining their efficiency. Some of the... 

In the presence of catalysts, heterogeneous catalytic cracking occms on the surface interface of the melted polymer and solid catalysts. The main steps of reactions are as follows diffusion on the surface of catalyst, adsorption on the catalyst, chemical reaction, desorption from the catalyst, diffusion to the liquid phase. The reaction rate of catalytic reactions is always determined by the slowest elementary reaction. The dominant rate controller elementary reactions are the linking of the polymer to the active site of catalyst. But the selectivity of catalysts on raw materials and products might be important. The selectivity is affected by molecular size and shape of raw materials, intermediates and products [36]. 

The sulfur-abstracting capacity of [(Cp )2Mo2Co2(CO)4( 3-S)2(/i4-S)] (64) vis-a-vis sulfur-containing molecules other than thiophene has been studied. For example, whereas sulfur abstraction from thiophene produces a mixture of hydrocarbons cracked to various extents (but notably no butadiene, which is a product of HDS of thiophene over heterogeneous catalysts), a completely clean reaction is seen for thiols (RSH) which are desulfurized to Thiophenol (PhSH) is desulfurized... 

Catalytic processes today dominate the production of sulfuric acid, ammonia, methanol, and many other industrial products. The cracking of mineral oils, the hydrogenation, transformation, and synthesis of hydrocarbons are almost all centered around catalytic conversions carried out with many different catalysts including some of highly specific action. Many more catalyzed reactions are being carried out in batch processes and in continuous operations, in heterogeneous and in homogeneous systems. 

---