Removal of chlorinated hydrocarbons from alkylsilanes

Claim 2

A process for purifying alkylsilanes to lower the content of chlorocarbon impurities, wherein said alkylsilanes have the formula, R.sup.i.sub.a SiX.sub.4-a wherein each R i is independently selected from hydrogen atoms and alkyl groups containing 1, 2, 3, 4, 5, or 6 carbon atoms; X is a halogen atom; and wherein a has a value of 1, 2, 3, or 4, said process comprising

Claim 3

(A) contacting crude alkylsilanes and a hydrogen-containing silane with a catalyst; wherein said crude alkylsilanes are a mixture which comprises as a major portion the alkylsilanes and as a minor portion the chlorocarbons; said chlorocarbons are selected from a group consisting of linear and branched alkylchlorides containing 3 or more carbon atoms and one or more chlorine atoms; said hydrogen-containing silane having the formula, R.sup.ii.sub.m H.sub.n SiX.sub.p, wherein each R ii is independently selected from alkyl groups containing 1, 2, 3, 4, 5, or 6 carbon atoms; X is defined above; m has a value of 0, 1, 2, or 3; n has a value of 1 or 2; p has a value of 0, 1, 2, or 3; and the sum of (m+n+p) must equal 4; and said catalyst is an effective Lewis acid forming material; (B) facilitating reaction of the chlorocarbons with the hydrogen-containing silane in contact with the catalyst to convert the chlorocarbons to linear or branched alkanes; (C) separating the catalyst from the alkylsilanes and alkanes; and (D) recovering alkylsilanes with lowered chlorocarbon content.

Claim 4

(A) contacting crude alkylsilanes and a hydrogen-containing silane with a catalyst; wherein said crude alkylsilanes are a mixture which comprises as a major portion the alkylsilanes and as a minor portion the chlorocarbons; said chlorocarbons are selected from a group consisting of linear and branched alkylchlorides containing 3 or more carbon atoms and one or more chlorine atoms; said hydrogen-containing silane having the formula, R.sup.ii.sub.m H.sub.n SiX.sub.p, wherein each R ii is independently selected from alkyl groups containing 1, 2, 3, 4, 5, or 6 carbon atoms; X is defined above; m has a value of 0, 1, 2, or 3; n has a value of 1 or 2; p has a value of 0, 1, 2, or 3; and the sum of (m+n+p) must equal 4; and said catalyst is an effective Lewis acid forming material; (B) facilitating reaction of the chlorocarbons with the hydrogen-containing silane in contact with the catalyst to convert the chlorocarbons to linear or branched alkanes; (C) separating the catalyst from the alkylsilanes and alkanes; and (D) recovering alkylsilanes with lowered chlorocarbon content.

Claim 5

A process according to claim 1, where the process further comprises separating the alkylsilanes from the alkanes.

Claim 6

A process according to claim 1, wherein the catalyst is selected from a group consisting of alumina, silica-alumina mixtures, zeolites, aluminum chloride, cobalt chloride, ferric chloride, copper chloride, stannous chloride, palladium chloride, and zirconium chloride.

Claim 7

A process according to claim 1, wherein the hydrogen-containing silane is a minor portion of the crude alkylsilanes.

Claim 8

A process according to claim 1, wherein the hydrogen-containing silane is added to the crude alkylsilanes.

Claim 9

A process according to claim 4, wherein additional hydrogen-containing silane is added to the crude alkylsilanes.

Claim 10

A process according to claim 1, wherein the hydrogen-containing silane is present in a stoichiometric excess relative to the amount needed to convert the chlorocarbons to alkanes.

Claim 11

A process according to claim 1, wherein the chlorocarbons are present in the crude alkylsilanes at a concentration of greater than about 10 parts per million on a weight basis.

Claim 12

A process according to claim 1, wherein contact is carried out in a batch mode.

Claim 13

A process according to claim 1, wherein contact is carried out in a continuous mode.

Claim 14

A process according to claim 1, wherein contacting the crude alkylsilanes, the hydrogen-containing silane, and the catalyst and facilitating reaction of the chlorocarbons with the hydrogen-containing silanes are effected at a temperature greater than about 25° C.

Claim 15

A process according to claim 1, wherein the crude alkylsilanes, the hydrogen-containing silane, and the catalyst are in contact for greater than about one minute.

Claim 16

A process according to claim 2, wherein separating the alkylsilanes from the alkanes is facilitated by distillation to recover alkylsilanes with enhanced purity.

Claim 17

A process according to claim 1, wherein the crude alkylsilanes are methylsilanes, the hydrogen-containing silane is methyldichlorosilane and the catalyst is selected from a group consisting of aluminum chloride, cobalt chloride, zirconium chloride, alumina, and silica-alumina mixtures; the methylsilanes, the methyldichlorosilane, and the catalyst are in contact in a liquid phase in a range from about 1 to 20 minutes at a temperature in a range from about 25° to 100° C.; and methylsilanes of enhanced purity are recovered by distillation.