Processes and systems for purifying silane
View Patent ↗Processes and systems for purifying silane-containing streams and, in particular, for purifying silane-containing streams that also contain ethylene are disclosed. The processes and systems may be arranged such that one or more ethylene reactors are downstream of light-end distillation operations.
1. A process for purifying a silane-containing stream, the stream comprising silane, ethylene and one or more compounds with a boiling point less than silane, the process comprising:
introducing the silane-containing stream into a reactor to convert ethylene to at least one of ethylsilane and ethane and to produce an ethylene-depleted stream relative to the silane-containing stream; and
introducing the ethylene-depleted stream into a heavy-ends distillation column to produce a silane-enriched overhead fraction and a silane-depleted bottoms fraction relative to the ethylene-depleted stream, the silane-depleted bottoms fraction being enriched in at least one of ethylsilane and ethane relative to the ethylene-depleted stream; and
introducing the overhead fraction produced from the heavy-ends distillation column into a light-ends distillation column to produce a silane-depleted overhead fraction and a silane-enriched bottoms fraction relative to the overhead fraction produced from the heavy-ends distillation column, the silane-depleted overhead fraction being enriched in compounds with a boiling point less than silane relative to the overhead fraction produced from the heavy-ends distillation column.
2. The process as set forth in claim 1 wherein the silane-containing stream comprises compounds having a boiling point greater than silane other than ethylsilane and ethane, wherein the silane-depleted bottoms fraction produced from the heavy-ends distillation column is enriched in such compounds.
3. The process as set forth in claim 2 wherein the one or more compounds having a boiling point greater than silane are selected from the group consisting of diethyl silane, toluene, dimethoxyethane and mixtures thereof.
4. The process as set forth in claim 1 wherein the silane-containing stream is heated to a temperature of at least about 100° C. prior to entry into the reactor.
5. The process as set forth in claim 1 wherein the silane-containing stream is pressurized to a pressure of at least about 2200 kPa prior to introduction into the reactor.
6. The process as set forth in claim 1 wherein the silane-containing stream is contacted with a zeolite catalyst in the reactor.
7. The process as set forth in claim 6 wherein the reactor comprises a zeolite catalyst in the form of a molecular sieve.
8. The process as set forth in claim 1 wherein the reactor comprises a zeolite-supported platinum, palladium or nickel catalyst.
9. The process as set forth in claim 1 wherein the one or more compounds having a boiling point less than silane are selected from the group consisting of hydrogen, nitrogen, and methane.
10. The process as set forth in claim 1 wherein at least about 75% of the ethylene introduced into the reactor in the silane-containing stream is converted to at least one of ethylsilane and ethane.