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A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other se

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order.

대표청구항 ▼

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other se

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order. m 1 which further comprises removing a portion of a dissolved hydrogen-containing species from said molten aluminum by exposing a large portion of said molten aluminum to said protective atmosphere while said furnace is being fired with said combustion mixture. 3. The process of claim 1 wherein said protective atmosphere contains less than 1% by volume of a hydrogen containing species. 4. The process of claim 3 wherein said protective atmosphere contains less than 0.1% by volume of a hydrogen containing species. 5. A process for melting an aluminum charge into molten aluminum and refining said molten aluminum to produce a refined molten aluminum having a low hydrogen content which comprises: A) introducing said charge into a direct fired furnace to expose said charge to radiant heat emitted from above said charge; B) combusting a combustion mixture layer of fuel and oxidant to form a combustion layer which generates said radiant heat and combustion reaction products within said furnace; C) introducing a substantially hydrogen-free protective atmosphere into said furnace at a vertical distance below said combustion mixture layer; and D) removing a portion of dissolved hydrogen from said molten aluminum by injecting an inert gas into said molten aluminum while melting said charge and refining said molten aluminum. 6. The process of claim 5 wherein said inert gas is injected into the molten aluminum prior to the complete melting of said charge into molten aluminum. 7. The process of claim 5 wherein said inert gas is a nitrogen or argon. 8. The process of claim 5 wherein a fluxing gas is added to said inert gas. 9. The process of claim 8 wherein said fluxing gas is chlorine. 10. The process of claim 5 wherein said protective atmosphere contains less than 1% by volume of a hydrogen containing species. 11. The process of claim 10 wherein said protective atmosphere contains less than 0.1% by volume of a hydrogen containing species.