Ethane dehydrogenation to ethylene and ethane oxidative dehydrogenation to ethylene
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I wonder what the market situation is for the technology of producing ethylene through ethane (oxidative) dehydrogenation? According to the available information, there were many studies in China around the year 2000, but fewer reports have appeared recently. What is the reason for this? Possible cause analysis: 1. No technical advantages over traditional steam cracking, such as still requiring high temperatures? 2. Is thermodynamic equilibrium limited at low temperatures, and is it difficult to develop highly active catalysts? I wonder if there are any other reasons?
The limitation of catalysts for ethylene production via thermal cracking dehydrogenation lies in the difficulty of finding catalysts that are highly active at low temperatures, exhibit high selectivity, good stability, and strong resistance to carbon deposition； The oxidation method does not require a catalyst; its advantage lies in low energy consumption. As it is an exothermic reaction, there is no need to use superheated saturated steam to reduce the gas pressure, thereby avoiding issues such as catalyst deactivation and carbon deposition. By introducing air directly at a ratio of n_air:n_ethane = 8:2, at a temperature of 850 degrees Celsius and with a residence time of 1.5 seconds, an ethane conversion rate of 92.2%, an ethylene selectivity of 63.2%, and an ethylene yield of 58.3% can be achieved. It is not yet clear which factories have such equipment; experts are needed to provide an answer!
:handshake:handshake:handshake:handshake:handshake So far, no significant breakthroughs have been seen. Oxidizing ethane via CO2 for dehydrogenation is indeed a hot topic in the academic community.
Another type is oxygen oxidation dehydrogenation. For example, a good yield of ethylene can be achieved at low temperatures; this technology has been under study for many years yet has not been put into industrial use. What are the difficulties? One: Catalyst? Second: the explosion limit issue?
The oxidation-dehydrogenation method is already in use abroad. In this process, air is introduced into the furnace tube where it reacts with ethane to produce ethylene and water. However, since no hydrogen is generated in this method, hydrogen is expensive in China, whereas its price is very low abroad, and the supply of hydrogen there is also substantial. It is said that in the United States, hydrogen is usually mixed with natural gas. Most importantly, China does not have any available ethane resources, so the significance of conducting such research is not very great; this is probably why the oxidation method is not used in China!
I saw your previous comment saying that the thermal pyrolysis method does not produce hydrogen? Is that so? It’s probably because the oxidation method doesn’t use hydrogen
It depends on the selectivity of raw materials and products as well as the production process route; domestic refineries generally choose the thermal cracking method to produce ethylene.