Coking and carburization resistant iron aluminides for hydrocarbon cracking

The cracking tube comprising:

• a first layer on an interior surface of the tube;
• and
• a second material surrounding the first layer,
• wherein the first layer is an iron aluminide alloy,
• wherein the iron aluminide alloy includes at least 2 vol. % transition metal oxides selected from oxides of aluminum, yttrium, cerium, zirconium or lanthanum.

A cracking tube comprising:

• a first layer on an interior surface of the tube;
• and
• a second material surrounding the first layer,
• wherein the first layer is an iron aluminide alloy, wherein the iron aluminide alloy comprises:
• 14-32 wt. % Al;
• 10-14 vol. % transition metal oxides;
• 0.003 to 0.020 wt. % B;
• 0.2 to 2.0 wt. % Mo;
• 0.05 to 1.0 wt. % Zr;
• 0.2 to 2.0 wt. % Ti;
• 0.10 to 1.0 wt. % La;
• 0.05 to 0.2 wt. % C;
• balance Fe;
• and
• optionally, ≦1 wt. % Cr.

A cracking tube comprising:

• a first layer on an interior surface of the tube;
• and
• a second material surrounding the first layer,
• wherein the first layer is an iron aluminide alloy.
• wherein the alloy is in the form of a sintered nanocrystalline intermetallic powder.

A method of reducing coking and carburization in a cracking tube having a metallurgically modified surface on the inner diameter surface thereof and the cracking tube is used in an environment in which hydrocarbon feedstock is thermally and/or catalytically converted to hydrocarbon products, comprising:

• heating the cracking tube to a first temperature at which cracking of hydrocarbon feedstock occurs;
• flowing hydrocarbon through the cracking tube;
• and
• producing an effluent containing a desired hydrocarbon product,
• wherein the metallurgically modified surface is an iron aluminide alloy with transition metal oxides in an amount effective to provide a coefficient of thermal expansion substantially the same as the coefficient of thermal expansion of a second material of the cracking tube over the temperature range of ambient to about 1000° C., and wherein the modified surface is substantially coke and carburization-free after a period of time in which a similar cracking tube without the metallurgically modified surface of iron aluminide alloy exhibits coking and carburization.

A method of reducing coking and carburization in a cracking tube having a metallurgically modified surface on the inner diameter surface thereof and the cracking tube is used in an environment in which hydrocarbon feedstock is thermally and/or catalytically converted to hydrocarbon products, comprising:

• heating the cracking tube to a first temperature at which cracking of hydrocarbon feedstock occurs;
• flowing hydrocarbon through the cracking tube;
• and
• producing an effluent containing a desired hydrocarbon product,
• wherein the metallurgically modified surface is an iron aluminide alloy,
• wherein the iron aluminide alloy comprises:
• 14-32 wt. % Al;
• 10-14 vol. % transition metal oxides;
• 0.003 to 0.020 wt. % B;
• 0.2 to 2.0 wt. % Mo;
• 0.05 to 1.0 wt. % Zr;
• 0.2 to 2.0 wt. % Ti;
• 0.10 to 1.0 wt. % La;
• 0.05 to 0.2 wt. % C;
• balance Fe;
• and
• optionally, ≦1 wt. % Cr.

In a process of producing hydrocarbon products from feedstock utilizing a cracking tube, the improvement comprising passing the feedstock through a cracking tube having a metallurgically modified surface of iron aluminide alloy disposed on an inner surface of the cracking tube such that feedstock is in fluid communication with the metallurgically modified surface, wherein the iron aluminide alloy comprises:

• 14-32 wt. % Al;
• 10-14 vol. % transition metal oxides;
• 0.003 to 0.020 wt. % B;
• 0.2 to 2.0 wt. % Mo;
• 0.05 to 1.0 wt. % Zr;
• 0.2 to 2.0 wt. % Ti;
• 0.10 to 1.0 wt. % La;
• 0.05 to 0.2 wt. % C;
• balance Fe;
• and
• optionally, ≦1 wt. % Cr.

In a cracking tube, the improvement comprising:

• a metallurgically modified surface of iron aluminide alloy disposed on an inner surface of the cracking tube, wherein the iron aluminide alloy comprises:
• 14-32 wt. % Al;
• 10-14 vol. % transition metal oxides;
• 0.003 to 0.020 wt. % B;
• 0.2 to 2.0 wt. % Mo;
• 0.05 to 1.0 wt. % Zr;
• 0.2 to 2.0 wt. % Ti;
• 0.10 to 1.0 wt. % La;
• 0.05 to 0.2 wt. % C;
• balance Fe;
• and
• optionally, ≦1 wt. % Cr.