High selectivities to ethylene by partial oxidation of ethane

Area of Science:

• Chemical Engineering
• Catalysis
• Oxidation Reactions

Background:

• Ethylene production predominantly relies on energy-intensive steam cracking.
• Selective oxidation of ethane to ethylene is challenging due to competing reactions forming CO and CO2.
• High-temperature reactions typically favor equilibrium products, making ethylene (a non-equilibrium product) difficult to obtain with high yield.

Purpose of the Study:

• To develop a highly selective process for ethylene production from ethane partial oxidation.
• To investigate the effect of hydrogen addition on ethane oxidation over a platinum-tin catalyst.
• To explore the potential of this method as an alternative to steam cracking.

Main Methods:

• Partial oxidation of ethane using a platinum-tin catalyst at 950°C.
• Addition of large amounts of hydrogen (H2) to the ethane/oxygen reaction mixture.
• Control of reaction parameters including temperature, contact time (approx. 10^-3 seconds), and reactant ratios.

Main Results:

• Achieved over 85% selectivity to ethylene at greater than 70% ethane conversion.
• Significantly suppressed the formation of carbon monoxide (CO) and carbon dioxide (CO2), reducing their yield from 20% to 5%.
• Observed no flames or explosions despite using a potentially explosive H2/O2 mixture in the presence of ethane.

Conclusions:

• The addition of hydrogen to ethane partial oxidation over a Pt-Sn catalyst is a highly effective method for selective ethylene production.
• The process operates safely and generates more hydrogen than consumed, allowing for a recyclable system.
• This catalytic approach shows significant promise for replacing conventional steam cracking for industrial ethylene synthesis.