Process for production of ethylene from ethane

The process for dehydrogenating a mixture of ethane and propane to produce a mixture of ethylene and propylene that includes

• a) providing a generally tubular, highly porous, asymmetric, ceramic membrane, and providing a heated reaction zone in a container into which the membrane is received,
• b) said membrane having been impregnated with a catalytically active metallic substance so as to create an intramembrane catalytic profile, with pore diameters less than 100 .ANG.,
• c) and passing an inlet stream of ethane and propane, carrying hydrogen in the range of 1.0% to 20% by volume, into contact with the treated membrane, at one side thereof at elevated temperature between 300.degree. and 800.degree. C. and in such manner as to cause hydrogen diffusion through the membrane to the opposite side thereof faster than ethane, ethylene, propane, and propylene, and removing an outlet stream of hydrogen from said opposite side of the membrane, and removing an outlet stream of ethylene and propylene from said one side of the membrane,
• d) whereby the dehydrogenation reactions, ethane to ethylene, and propane to propylene proceed relatively rapidly, to produce hydrogen that passes through the membrane, with the result that the conversions of ethane to ethylene and propane to propylene exceed the normal thermodynamic equilibrium values for the temperature and pressure of the reactor without removal of hydrogen with the reaction zone,
• e) the membrane characterized as having relative permeabilities for H.sub.2, ethane, ethylene, propane, and propylene that are within 90% of Knudsen flow component diffusivities,
• f) controlling the flow of said inlet and outlet streams to maintain a differential pressure between said inlet ethane and propane stream, and said outlet hydrogen stream, of between 10 and 100 psi,
• g) maintaining said container at said elevated temperature and radiating heat from said container toward said reaction zone to maintain said elevated temperature,
• h) providing a pelleted catalyst material adjacent to the side of the membrane to which said inlet stream of ethane and propane is passed,
• i) said container being metallic and substantially tubular, and including the initial step of removing an ethylene-containing gas stream from the container,
• j) and employing argon or steam to sweep H.sub.2 away from said opposite side of the membrane, and employing argon or steam to mix with ethane and propane fed to said one side of the membrane.

The process of dehydrogenating an alkane or a mixture of alkanes to produce alkene or a mixture of alkenes, that includes

• a) providing a generally tubular, highly porous, asymmetric, ceramic membrane, and providing a heated reaction zone in a container into which the membrane is received,
• b) said membrane having been impregnated with a catalytically active metallic substance so as to create an intramembrane catalytic profile, with pore diameters less than 100 .ANG.,
• c) and passing an inlet stream of said alkane or mixture of alkanes, carrying hydrogen in the range of 0.1% to 20% by volume, into contact with the treated membrane, at one side thereof at elevated temperature between 300.degree. and 800.degree. C., and in such manner as to cause hydrogen diffusion through the membrane to the opposite side thereof faster than alkane, alkene, or said mixture of alkanes or alkenes, and removing an outlet stream of hydrogen from said opposite side of the membrane, and removing an outlet stream of alkene or a mixture of alkenes from said one side of the membrane,
• d) whereby the dehydrogenation reactions, alkane to alkene, or said mixture of alkanes to said mixture of alkenes, proceeds relatively rapidly, to produce hydrogen that passes through the membrane, with the result that the conversions of alkane to alkene, or mixture of alkanes to mixture of alkenes, exceed the normal thermodynamic equilibrium value for the temperature and pressure of the reactor without removal of hydrogen from the reaction zone,
• e) the membrane characterized as having relative permeabilities for H.sub.2, alkane, alkene, mixture of alkanes and mixture of alkenes that are within 90% of Knudsen flow component diffusivities,
• f) controlling the flow of said inlet and outlet streams to maintain a differential pressure between said inlet stream of alkane or mixture of alkanes, and said outlet hydrogen stream, of between 10 and 100 psi,
• g) maintaining said container at said elevated temperature and radiating heat from said container toward said reaction zone to maintain said elevated temperature,
• h) providing a pelleted catalyst material adjacent to the side of the membrane to which said inlet stream of said alkane or mixture of alkenes is passed,
• i) said container being metallic and substantially tubular, and including the initial step of removing an ethylene-containing gas stream from the container,
• j) and employing argon or steam to sweep H.sub.2 away from said opposite side of the membrane, and employing argon or steam to mix with alkane fed to said one side of the membrane.