Advantages & Disadvantages of Using Zeolites

 




    Zeolites are very stable solids that withstand many other materials in the kinds of environmental environments that threaten them. Since they have relatively high melting points (over 1000 ° C), extreme temperatures will not affect them, and they don't burn. They also withstand high temperatures, do not dissolve in the water, and do not oxidize in water or other inorganic solvents. As zeolites a very stable substance, they do not cause health problems to humans, whether through skin contact or inhalation. However, in fibrous form, they may have carcinogenic effects. Besides, zeolites are synthesized based on naturally occurring minerals; thus, they also don't have any harmful environmental impacts. In the petrochemical industry, zeolites are very common as catalysts. They are used in catalytic crackers to split massive hydrocarbon molecules into oil, diesel, kerosene, and waxes, and all sorts of other petroleum by-products.

Numerous pores in the open structure of a zeolite are like thousands of tiny test tubes in which atoms and molecules become trapped and chemical reactions readily occur. Zeolite catalysts may operate selectively on particular molecules since the pores in a specific zeolite are of a defined size and form, hence why they were also known as shape-selective catalysts (they can select the molecules they work on in other ways beside shape and size). Zeolites can be used repeatedly, as most of the other catalysts. Zeolites have become more relevant over the years. Industrial catalysis without zeolites is hard to imagine due to their outstanding properties that can be simplified as below:

  • High surface area
  • Pore sizes in the molecular range;
  •  High adsorption capacity
  •  Have controllable adsorption properties
  •  Have inherent active sites
  •   Shape selectivity
  •    Very stable/ unreactive

Catalytic cracking is one of the industrial catalysis processes that used zeolites as the catalyst. It's a method in the essential oil industry where petroleum vapor moves through catalysts (zeolites) low-density bed, allowing the heavier fractions to 'crack,' creating smaller, more desirable goods. They are used in the petrochemical industry on an unprecedented scale to manufacture polyolefins. There are many benefits and drawbacks of the use of the catalyst in the cracking process.

Advantages of catalytic cracking process:

  • Catalytic cracking takes place at lower temperature and pressure (3000C -4000C and 1-5kg/cm2)
  • Catalytic cracking yields a high quantity of branched-chain, unsaturated, aromatic hydrocarbons
  • Catalytic cracking is a better-controlled process
  • Petrol obtained by catalytic cracking has lesser sulfur content.
  • It increased the lower heating value of the fuel.
  • Better burning due to usage of gaseous hydrocarbons.
  • The use of catalyst in the cracking process is cheaper than other cracking methods  because it saves energy as lower temperatures and pressures are used

Disadvantages of catalytic cracking processes:

  • Incomplete conversion of the fuel

  • Loss of activity in the catalyst due to the deposition of undesirable carbonaceous products, metallic compounds, and asphaltenes on the catalyst surface (coking).
  • The structural changes including thermally or attrition of catalyst lead to the catalyst deactivation








REFERENCES

(Bhaskar, Rao., Modern Petroleum Refinery Processes (5th ed.). Oxford & IBH Publishing Co. Pvt Ltd., New Delhi.


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