WO2015006173A1

WO2015006173A1 - Chlorosilane recovery from gas streams

Info

Publication number: WO2015006173A1
Application number: PCT/US2014/045501
Authority: WO
Inventors: Larry M. COLEMAN; Mark William Dassel
Original assignee: Centrotherm Photovoltaics Usa, Inc.
Priority date: 2013-07-12
Filing date: 2014-07-03
Publication date: 2015-01-15

Abstract

A chlorination process that includes (a) providing a reactor containing a reaction catalyst, the reaction catalyst comprising a solid support and nitrogen atoms; (b) introducing reactants to the reactor, the reactants including hydrogen chloride and at least one silicon compound selected from silane, monochlorosilane, dichlorosilane and trichlorosilane, where the reactants are characterized by a molar ratio of hydrogen chloride to compounds containing silicon (HCl:Si) and are also characterized by a molar ratio of Si-Cl bonds to compounds containing silicon (Si-Cl:Si); and (c) contacting the reactants with the reaction catalyst to provide products, the products characterized in comparison to the reactants as having a lower HCl:Si ratio and a higher Si-Cl:Si ratio, and related systems for achieving the process.

Description

CH LOROSILANE RECOVERY FROM GAS STREAMS

FIELD OF TH E INVENTION

[0001] The present invention relates generally to chemical processes whereby the hydrogen chloride content of a chlorosilane gas stream is reduced, and systems related thereto.

BACKGROUND

[0002] The most commonly used method for manufacture of bulk polysilicon is the chemical vapor deposition of silicon onto a smaller heated rod or heated granule. This process is commonly referred to as chemical vapor deposition (CVD), with the two major alternatives being deposition on an electrically heated rod (i.e., the Siemens process), and deposition on an externally heated fluidized bed of smaller seed granules. In either process, the silicon CVD growth is accompanied by the co- generation of a vent gas, sometimes referred to as an off -gas (also written as off gas), which contains hydrogen chloride (HCI), hydrogen (H₂), and chlorosilane species. The chlorosilane off-gas species: dichlorosilane (DCS), trichlorosilane (TCS) and silicon tetrachloride (STC), are valuable materials, but their value is often diminished when they are in admixture with hydrogen chloride.

[0003] U.S. Patent 5,401,872 discloses a process for recovering chlorine present in a gaseous vent stream. The process provides for contacting a gaseous vent gas comprising hydrogen chloride and a hydrochlorosilane with a metallic or

organometallic catalyst to form a more highly chlorinated silane. In other words, the chlorination of the hydrochlorosilane captures the chlorine from the hydrogen chloride as a substituent of the resulting, more highly chlorinated, chlorosilane.

Metals disclosed as being suitable are palladium, platinum, rhodium, ruthenium, nickel, osmium and iridium. The metallic catalyst may be supported on a solid support, e.g., carbon or silicon, or it may be unsupported. In either event, metal may end up contaminating the product gas stream, which is highly disadvantageous when that gas stream is used in the production of polysilicon, since the metal may deposit in the polysilicon and thus create lower-grade silicon.

[0004] There is a need for a process that can transfer the chloride present as hydrogen chloride in a hydrochlorosilane-containing vent gas, to provide a product stream enriched in chlorosilane and/or hydrochlorosilane, but without introducing any additional metallic contamination.

SUMMARY

[0005] The present disclosure provides a process by which the HCI present in a chlorosilane vapor stream can be reacted with the chlorosilane also present in the vapor to create a vapor stream having extremely low amounts of residual HCI, at or approaching insignificant amounts of HCI. In one aspect, the process includes contacting the chorosilane vapor stream with an amine catalyst, i.e., a catalyst that comprises amine groups bonded to a solid support, where the amine groups may be any secondary, tertiary or quaternary amine. A suitable catalyst is an ion exchange resin including but not limited to Rohm & Haas A-21 catalyst which is a weak base tertiary methyl amine supported on a polystyrene/divinyl benzene bead. In general, suitable ion-exchange resins may be weak base or strong base, tertiary amine or quaternary amine. The present disclosure provides for the reaction of HCI with chlorosilanes to react Si-H bonds to form Si-CI bonds. For example, HCI may be reacted with monochlorosilane to produce dichlorosilane. As another example, HCI may be reacted with dichlorosilane to produce trichlorosilane and hydrogen. As yet another example, HCI may be reacted with trichlorosilane to product silicon tetrachloride and hydrogen.

[0006] More generally, the present disclosure provides for the consumption of HCI from a gas stream with the concomitant formation of a more highly chlorinated silicon species. The present disclosure includes the preparation of other halogenated compounds, i.e., other than halogenated silicon compounds, from compounds having hydrogen bonded to an atom selected from the atoms in the periodic table from Group III, Group IV, and Group V. For example, phosphorous-hydrogen bonds may be converted to phosphorous-chloride bonds according to the present disclosure. For instance, PH3 may be converted to PCI3 by introducing hydrogen chloride and phosphine into a reactor with the reaction catalyst as disclosed herein. As another example, boron-hydrogen bonds may be converted to boron-chloride bonds according to the present disclosure. For instance, B2H6 may be converted to BCI3 by introducing hydrogen chloride and diborane into a reactor with a reaction catalyst as disclosed herein. As a further example, germanium-hydrogen bonds may be converted to germanium-chloride bonds according to the present disclosure. For instance, GeHCb may be converted to GeCU by introducing hydrogen chloride and GeHCb into a reactor with a reaction catalyst as disclosed herein. In each of these cases, the hydrogen chloride and the compound containing the hydrogen bond to a Group III, IV or V atom, are each in the gas phase when they are contacted with the reaction catalyst disclosed herein. While the process of the present disclosure is described herein for convenience primarily using silicon-hydrogen bond reaction and silicon-chloride bond formation as an example, the process of the present disclosure is not limited to silicon compounds.

[0007] In one aspect, the present disclosure includes processing technology which by way of example includes: (a) a de-hydrochlorination reaction which takes place in the gas phase when the resin has been dried to less than 0.1 wt% moisture, preferably to under 100 ppm (v/v) by passing dry nitrogen or other dry gas through it. The drying gas is preferably heated to about 50°C, but lower temperatures may be used with longer drying times. In the case where the amine catalyst includes an organic polymeric support, the drying temperature may be less than the softening

temperature of the support, or else the support will soften and may plug up the reactor. Thus, when the support is an organic polymer, a drying temperature of less than 100°C may suitably be employed. In addition to softening, if the drying temperature is taken to between 100 and 200°C, the catalyst may de-aminate, i.e., lose amine groups. Accordingly, catalyst drying temperatures of less than 100°C are preferred. Hydrogen gas may advantageously be included in the chlorosilane vapor stream as an inert material which absorbs the heat from the chlorination reaction. By absorbing the heat of chlorination, the hydrogen helps maintain the temperature within the chlorination reactor below the point at which the catalyst softens and loses its structural integrity.

[0008] The solid support used in the chlorination process may optionally be further characterized by one, or more than one (e.g., any two, any three, or any four, etc.) of the following features: the solid support is an organic polymer having a plurality of C-H bonds; the solid support is polystyrene that has been cross-linked with divinyl benzene; the organic polymer may have non-catalytic nitrogen-containing substituents; the reactive catalytic groups that are chemically attached to, i.e., bonded to, the solid support are nitrogen-containing substituents selected from amino (solid support-N hh), alkylamino (solid support-N H-alkyl), and dialkyalmino (solid support- N(alkyl)2) families; the catalytic nitrogen-containing substituents comprise

dimethylamino groups; the combined solid support and catalyst groups are a weak base anion exchange resin; the organic polymer comprises nitrogen-containing substituents; the nitrogen-containing substituents are selected from amino, alkylamino, and dialkylamino; the nitrogen-containing substituents comprise dimethylamino; the solid support is a weak base anion exchange resin.

[0009] Optionally, the solid support may be conditioned prior to being contacted with the reactants. In one aspect, the solid support is conditioned prior to step b, or prior to step c, the conditioning comprising dehydrating the solid support with a hot gas, where optionally the hot gas is selected from hydrogen (H2) and nitrogen (N 2) gas, and where, for example, dehydration is accomplished by passing the hot gas through the solid support under conditions effective to dehydrate the solid support. In another aspect, which may be performed in addition to, or in lieu of, the dehydration conditioning step, the solid support is conditioned prior to step b, or prior to step c, the conditioning comprising exposing the solid support to gaseous chlorosilane in the absence of hydrogen chloride. In one aspect, the solid support is first dehydrated, and then it is exposed to gaseous chlorosilane in the absence of hydrogen chloride.

[0010] Suitable reactor operating conditions are selected to achieve desired products from reactants, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first molar ratio of Si-CI bonds to silicon compounds (Si-CI :Si); and the products are characterized in comparison to the reactants by having a lower HChSi ratio and a higher Si-CI :Si ratio. Optionally, the reactants that enter the reactor, and the products that exit the reactor, and the silicon compounds within the reactor, are all in the gas phase. A suitable reactor operating temperature is in the range of 25-100°C. Alternatively, all of the named materials may be in the liquid phase. Although it is possible to operate the reactor in a two phase mode, i.e., having both liquid and gas phases present within the reactor, such a mode of operation is generally disfavored since it can result in reactor by-passing and incomplete HCI reaction. In one embodiment, the reactor feed can be cooled to provide both a liquid and a gas stream, whereupon the liquid stream is decanted from the gas stream and then either the liquid stream is fed into the reactor while maintaining an all-liquid phase within the reactor, or the gas stream may be fed into the reactor while maintaining an all-gas phase within the reactor, or both liquid and gas streams may be fed respectively into an all-liquid reactor and a separate all- gas reactor.

[0011] In another aspect, the present disclosure provides a system for performing the process previously described. For example, the present disclosure provides a system comprising a first reactor, the first reactor comprising: (a) a reaction catalyst comprising a solid support with nitrogen atoms bonded to the solid support; (b) a gas phase atmosphere in contact with the reaction catalyst, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first molar ratio of Si-CI bonds to silicon compounds (Si-ChSi); and (c) a temperature within the first reactor. The temperature of the feed to the reactor and the temperature at all points within the reactor is preferably maintained a bove the dew point of the combined feed and/or internal reaction mixture at the system operating pressure to prevent partial condensation and resultant unwanted two-phase flow within the reaction catalyst bed. The system operating pressure may be as low as 1 atmosphere or as high as 15 atmospheres, or around 6 to 8 atmospheres.

[0012] The system may comprise a second reactor. The second reactor comprises: (a) a reaction catalyst comprising a solid support bonded to nitrogen atoms; (b) a gas phase atmosphere in contact with the reaction catalyst, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first molar ratio of Si-CI bonds to silicon compounds (Si-CI:Si); and (c) a temperature within the second reactor.

Optionally, the reaction catalyst present in the first reactor is identical to the reaction catalyst present in second reactor. Optionally, the product from the first reactor is used as the reactant in the second reactor, and accordingly the molar ratio of hydrogen chloride to silicon compounds (HChSi) in the first reactor is greater than the molar ratio of hydrogen chloride to silicon compounds in the second reactor, and the molar ratio of Si-CI bonds to silicon compounds (Si-CI :Si) in the first reactor is less than the molar ratio of Si-CI bonds to silicon compounds in the second reactor. In one aspect, a cooling unit is positioned between the first and second reactors, where the cooling unit provides cooling for the product from the first reactor (an upstream reactor), before that product is utilized as a reactant in the second (downstream) reactor.

[0013] The details of one or more embodiments are set forth in the description below. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Other features, objects and advantages will be apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWING

[0014] Features of the present disclosure, its nature and various advantages will be apparent from the accompanying drawing and the following detailed description of various embodiments.

[0015] Figure 1 illustrates an exemplary system of the present invention, including optional features.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention may be understood more readily by reference to the drawing, the following detailed description of the preferred embodiments of the invention and the Examples included herein. It is to be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting. It is further to be understood that unless specifically defined herein, the terminology used herein is to be given its traditional meaning as known in the relevant art. The headings used within this document are only being utilized to expedite its review by the reader, and should not be construed as limiting the invention or claims in any manner. As used throughout this document, including the claims, the singular form "a", "an", and "the" include plural references unless indicated otherwise. For example, "a" reactor includes one or more reactors. As another example, "a" gas stream refers to one or more gas streams.

[0017] In one aspect, the present disclosure provides a process for chlorosilane manufacture. This process may be referred to as a chlorination reaction in that Si-H bonds are converted to Si-CI bonds, with hydrogen chloride (HCI) serving as the chloride donor. The process includes introducing a mixture comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane (S1 H4), monochlorosilane (MCS, CIS1 H3), dichlorosilane (DCS, CI2S1 H2) and trichlorosilane (TCS, CI3S1 H) to a reactor. Within the reactor there is an amine compound which facilitates the transfer of chloride from the hydrogen chloride to the silicon compound so as to form the chlorosilane. The reactor operates under conditions that allow for this transfer, e.g., suitable temperatures and hold up time. The reactor may be referred to as a chlorination reactor. REACTION CATALYST

[0018] In one aspect, the process of the present disclosure includes providing a reactor that contains a reaction catalyst, the reaction catalyst comprising a solid support, the solid support comprising a reactive site for a chlorination reaction, where the reactive site may comprise nitrogen atoms, the nitrogen atoms preferably in the form of amine groups. The solid support may be organic or inorganic, e.g., an organic polymer or an inorganic ceramic or zeolite. A suitable organic polymer has a carbon backbone, is formed by polymerization of an organic monomer, and has a plurality of C-H bonds, such as polystyrene and copolymers thereof. In order to enhance the structural and thermal stability of the organic polymer, the polymer may be cross- linked. For example, when the polymer is formed from the polymerization of styrene, some divinyl benzene may be admixed with the styrene to provide cross-linking. In this way, a polystyrene with divinylbenzene cross-linking may be prepared. In one aspect, the reaction catalyst is metal-free, i.e., does not comprise any substantial amount of metal such as palladium, platinum, rhodium, ruthenium, nickel, osmium or iridium.

[0019] The reactive sites comprise one or more atoms that facilitate the transfer of chloride from hydrogen chloride to a different atom, that is, an atom other than hydrogen, for example silicon. An exemplary reactive site comprises a (i.e., one or more) nitrogen atom having an N-H bond, e.g., a nitrogen atom in the form of an amine functional group which may be covalently bonded to the solid support. In such a case, at a minimum, the amine will be a primary amine, i.e., the nitrogen of the amine group will be bonded to at least one atom other than hydrogen, e.g., a carbon of the solid support. The amine group may be further substituted with one, two or three non-hydrogen chemical groups, to provide a secondary, tertiary or quaternary amine, respectively. In various aspects, the amine compound is a primary (solid support-N hh), secondary (solid support-N H-R) or tertiary amine (solid support-N(R)2) where R is not hydrogen and may be alkyl, or the amine compound is a secondary or tertiary amine, or the amine compound is a tertiary amine, or the amine compound is a secondary amine. In one aspect, the amine group is selected from amino (-N H2), alkylamino (-NH(alkyl)), and dialkylamino (-N(alkyl)2), where each alkyl may be characterized as having, for example, 1-6 carbon atoms, or 1-4 carbon atoms, or 1-2 carbon atoms. The nitrogen atom-containing substituents on the solid support are, in one aspect, dimethylamino. The nitrogen of the reactive catalytic sites is not N=N, i.e., is not two nitrogen atoms bonded together through a double bond. As referred to herein, an amine group may be in the form of an acid addition, e.g., the HCI salt of an amine group.

[0020] Suitable reaction catalysts having cross-linked organic solid supports and a plurality of amine functional groups are ion exchange resins, for example, anion exchange resins. Ion exchange resins are available from many commercial suppliers. A suitable ion exchange resin is known by the trade name AM BERLYST™ formerly sold by Rohm & Haas Company (Philadelphia, PA) and now sold by the Rohm & Haas division of Dow Chemical (Midland, Ml). A suitable AMBERLYST™ resin is

AM BERLYST™ A21, which comprises a solid support formed of polystyrene cross-linked with divinyl benzene and containing dimethyl amino substituents. Ion exchange resins are known to be useful when in contact with aqueous liquids, e.g., water. The present disclosure surprisingly finds that these ion exchange resins may be used in the present process, after complete or almost complete dehydration, the disclosure also including the feature that the reactants and the products of the process may all be in the gas phase.

[0021] The amine functional group is highly efficient in facilitating the chlorination of silicon compounds having Si-H bonds. In other words, a small amount of amine functionality is capable of achieving a large amount of chlorination. The amine compound may effectively catalyze the conversion of Si-H bonds to Si-CI bonds, using hydrogen chloride as the chlorine source. Accordingly, the amine compound in combination with the solid support may be referred to herein as the amine catalyst, or the catalyst for the chlorination reaction, or the reaction catalyst.

[0022] Optionally, the reaction catalyst may be conditioned prior to being contacted with the reactants. In one aspect, the reaction catalyst is conditioned by a dehydration step, whereby water is removed from the reaction catalyst. Dehydration may be achieved by passing hot gas across the catalyst. Suitable gases include hydrogen ( H2), nitrogen ( N2) and argon. The dehydration may be performed until no measurable amount of water is present on the catalyst, or until the water content is less than 0.1 wt% moisture, or until the water content is under 100 ppm (v/v). The drying gas may be heated to above ambient temperature, i.e., above 25°C, before being passed through the reaction catalyst. For example, the drying gas may be heated to about 30°C, 40°C, 50°C, 60°C, 70C, or 80°C. A higher temperature generally achieves a faster rate of dehydration, however a lower temperature may be used with longer drying times. In the case where the amine catalyst includes an organic polymeric support, the drying temperature is desirably less than the softening temperature of the support, or else the support will soften and may plug up the reactor. Thus, when the support is an organic polymer, a drying temperature of less than 100°C may suitably be employed. In addition to softening, if the drying temperature is taken to between 100°C and 200°C, the catalyst may de-aminate, i.e., lose amine groups. Accordingly, temperatures less than 100°C are preferred for dehydration.

[0023] In another aspect, which may be performed in addition to, or in lieu of, the dehydration conditioning step, the reaction catalyst is conditioned by exposing the catalyst to gaseous chlorosilane in the absence of hydrogen chloride. In one aspect, the reaction catalyst is first dehydrated, and then it is exposed to gaseous chlorosilane in the absence of hydrogen chloride.

SILICON COMPOUN DS

[0024] The process of the present disclosure achieves the chlorination of at least one silicon compound selected from the group consisting of silane (SihU), monochlorosilane (MCS, CIS1 H3), dichlorosilane (DCS, CI2S1 H2) and trichlorosilane (TCS, CI3S1 H ). In effect, the chlorination reaction of the present disclosure converts at least one Si-H bond to a Si-CI bond. For example, TCS may be converted to silicon tetrachloride (STC); DCS may be converted to one or both of TCS and STC; MCS may be converted to one or more of DCS, TCS and STC; and silane may be converted to one or more of MCS, DCS, TCS and STC.

[0025] As used herein, the term chlorosilane will refer to the compounds which have chloride-silicon bonds such as STC, TCS, DCS and MCS. The term hydrosilane will refer to compounds that contain a hydrogen-silicon bond, such as silane, MCS, DCS and TCS. The term hydrochlorosilanes will refer to the compounds that have both hydrogen-silicon and chloride-silicon bonds, such as TCS, DCS and MCS. Silane will refer to SihU. The silicon reactants for the chlorination process of the present disclosure may be selected from hydrosilane, or silane and hydrochlorosilanes, or from the group of compounds referred to as hydrochlorosilanes, or from one or more of silane, MCS, DCS and TCS individually specified.

[0026] Thus, in one aspect, the present disclosure provides a process that includes introducing reactants to a reactor, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane. The reactants may be characterized by a ratio of hydrogen chloride to compounds containing Si (HChSi). The ratio may be based on the weight or the number of each of the components in the reactants. For example, the ratio may be calculated based upon the number of hydrogen chloride molecules present in the reactants, and the number of silicon- containing compounds present in the reactants. When the ratio is based on the number of components, it is convenient to express those numbers as moles of a component and then calculate a ratio based on those molar values, to provide a molar ratio, as opposed to a ratio based on relative weights of the components. Unless otherwise specified, the ratios referred to herein will be molar ratios, i.e., ratios based on amounts of a component rather than weights of a component. When the process is operated in either a batch mode or a continuous mode, an aliquot of the reactant may be obtained and analyzed to measure the amount of hydrogen chloride and the total amount of silicon compounds present in the feedstock to the reactor, on either a molar or weight basis depending on the analytical method. The moles of hydrogen chloride may be determined, and the moles of silicon compounds may be determined, in order to determine the molar ratio of hydrogen chloride to silicon compounds present in the reactants, where this ratio may be referred to as a molar ratio of hydrogen chloride (HCI) to compounds containing X (HCI:X) where X may represents silicon or other elements as mentioned elsewhere herein.

[0027] In addition, or alternatively, the reactants may be characterized by a ratio of Si-CI bonds to compounds containing silicon (Si-CI:Si). In this case, an aliquot of the reactant mixture may be obtained and analyzed, for example, by gas chromatography. The relative or absolute (compared to an internal standard) amounts of silane, monochlorosilane, dichlorosilane and trichlorosilane may be determined, and then the number of Si-CI bonds may be calculated, based on knowledge that silane has no Si-CI bonds, monochlorosilane has one Si-CI bond, dichlorosilane has two Si-CI bonds, and trichlorosilane has three Si-CI bonds. From these measurements and determinations, the Si-CI :Si ratio may be determined. The ratio may be based on the number of moles of the Si-CI bonds and the number of moles of silicon-containing compounds. In other words, the reactants may be characterized by a molar ratio of X-CI bonds to compounds containing X (X-CI:X) where X may represent silicon or other elements as mentioned elsewhere herein.

[0028] The well-known Siemens CVD reaction produces polysilicon and an off gas comprising hydrogen, hydrogen chloride, STC, TCS and DCS. This off gas may be used to provide the source of both the hydrogen chloride and the silicon compounds needed in the present process. In the event that this off gas is used in the present process, the off gas may be diluted with one or more of hydrogen, hydrogen chloride, MCS, DCS, and TCS before the off gas is admitted to the chlorination reactor.

[0029] The present disclosure includes the preparation of other halogenated compounds, i.e., other than halogenated silicon compounds, from compounds having hydrogen bonded to an atom "X" (also referred to as an element "X") selected from the atoms in the periodic table from Group I II, Group IV, and Group V. For example, phosphorous-hydrogen bonds may be converted to phosphorous-chloride bonds according to the present disclosure. For instance, PH3 may be converted to PCI3 by introducing hydrogen chloride and phosphine into a reactor with the reaction catalyst as disclosed herein. As another example, boron-hydrogen bonds may be converted to boron-chloride bonds according to the present disclosure. For instance, B2H6 may be converted to BCI3 by introducing hydrogen chloride and diborane into a reactor with a reaction catalyst as disclosed herein. As a further example, germanium-hydrogen bonds may be converted to germanium-chloride bonds according to the present disclosure. For instance, GeHCb may be converted to GeCU by introducing hydrogen chloride and GeHCb into a reactor with a reaction catalyst as disclosed herein. In each of these cases, the hydrogen chloride and the compound containing the hydrogen bond to a Group III, IV or V atom, are each in the gas phase when they are contacted with the reaction catalyst disclosed herein. While the process of the present disclosure is described herein for convenience primarily using X = Si, i.e., silicon- hydrogen bond reaction and silicon-chloride bond formation as an example, the process of the present disclosure is not limited to silicon compounds.

[0030] For example, in one aspect the present disclosure provides a chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which optionally may include nitrogen atoms, e.g., nitrogen atoms bonded to hydrogen;

b. providing first reactants at a first temperature, the first reactants comprising hydrogen chloride and at least one compound having an X-H bond where X is an atom selected from the atoms of Group II I, Group IV and Group V of the periodic table, the first reactants characterized by a first molar ratio of hydrogen chloride (HCI) to compounds containing X (HCI:X) and also characterized by a first molar ratio of X-CI bonds to compounds containing X (X- CI:X);

c. introducing the first reactants into the first reactor; and

d. contacting the first reactants with the reaction catalyst to provide first products upon exiting from the first reactor and to generate heat, the first products characterized in comparison to the first reactants as having a lower

HCI:X molar ratio and a higher X-CI:X molar ratio.

[0031] Optionally, the feedstock to a chlorination reactor may contain reactive silicon compounds in addition to reactive boron and/or phosphorous compounds. For clarity, a reactive silicon compound has a Si-H bond and is in the gas phase at a temperature between 25-100°C at atmospheric pressure. Likewise, a reactive boron or phosphorous compound has a B-H or P-H bond, respectively, and is in the gas phase at a temperature between 25-100°C at atmospheric pressure. For example, the feedstock may contain primarily reactive silicon compounds, and minor amounts of reactive boron and/or phosphorous compounds, where the boron and phosphorous compounds are effectively undesired impurities. By converting both the reactive silicon compounds as well as the reactive boron and/or phosphorous compounds to the corresponding chlorinated (or more highly chlorinated) compounds, it may be easier to separate the boron and phosphorous compounds from the desired silicon compounds, thereby enhancing the purity of the silicon compounds. More generally, the teachings of the present invention may be applied to Group 3, 4 and/or 5 hydrides.

REACTOR DESIGN & OPERATION

[0032] The reactor may be a carbon steel shell with catalyst retaining screens at both ends and provision for uniform gas distribution into the catalyst bed contained within the shell. The material of construction is not limited to carbon steel, but this is an adequate and an economic choice. Typically the length of the shell will exceed the diameter of the shell. Representative length to diameter shell ratios are 1:1 to 20: 1, but lesser or greater ratios may be employed. The reactor comprises catalyst, where the catalyst is added to the reactor. In other words, the catalyst is not physically or chemically bound to the inside wall of the reactor, but is instead introduced into the reactor, and typically sits on a screen within the reactor. In the event the catalyst wears out or needs to be regenerated, it can be removed and fresh catalyst placed into the reactor.

[0033] The reactor may contain more than one entrance port whereby reactants are introduced into the reactor. For example, and in the case where the reactor has a single exit port whereby products exit from the reactor, the reactor may have a first entrance port and a second entrance port. The first and second entrance ports are located at different distances from the exit port, so that reactants that enter the reactor through the first entrance port have a different hold up time within the reactor than reactants that enter the reactor through the second entrance port. The incorporation and use of multiple entrance ports may be advantageously utilized to mitigate the presence of unwanted hot spots that might otherwise form on the catalyst. By introducing supplemental HCI into multiple ports the ratio of the first reactant feed (i.e., CVD off gas) to second reactant feed (i.e., Supplemental HCI) is maximized at any given HCI feed location. This dilution mitigates hot spots.

[0034] The reactor may have internal cooling elements which may be used to withdraw at least some of the heat generated by the chlorination reaction. For instance, the reactor may be fitted with cooling coils that pass through the reaction catalyst and/or space adjacent to the reaction catalyst through which products or partially converted reactants pass on their way to the exit port. The cooling coils may contain circulating fluid that absorbs and withdraws heat from the reactor. The use of internal cooling elements is one approach to temperature management as discussed later herein.

[0035] The hydrogen chloride and suitable silicon compounds are introduced to the reactor under reaction conditions that provide for the desired chlorination reaction, i.e., the transfer of chlorine from hydrogen chloride to a silicon compound. The hold-up time is a measure of how long the reactants are inside of the reactor before they exit the reactor. According to the present process, the hold-up time may, in various embodiments, range from 0.1 to 10 seconds, or from 0.5 to 5 seconds, or from 1 to 2 seconds. If the reactants are entirely in the liquid phase, then the hold-up time will generally be longer, on the order of 5-30 minutes.

[0036] The reactor will produce a product, typically a product that is entirely in the gas phase, which will exit from the reactor. Accordingly, the reactor may comprise an exit port suitable for the exit of gas from the reactor. The product will have a composition, where that composition may be characterized in terms including a mass or molar concentration of chlorosilanes in the product.

TEMPERATURE MANAGEMENT

[0037] The chlorination reaction as disclosed herein is an exothermic reaction.

In other words, the transfer of chlorine from HCI to hydrosilane proceeds with the generation of heat. In a related aspect, the present disclosure provides temperature monitoring and temperature management for the chlorination reaction, for example, the disclosure provides methods and systems to maintain the temperature within the reactor within a pre-determined range despite the generation of heat. Before describing the approaches and objectives for temperature management, it should be noted that there may be more than one temperature within the reactor. There will be a so-called bulk temperature, which refers to the temperature recorded when a thermocouple or other temperature monitoring means is placed into the gas that is flowing through the reactor. This bulk temperature will be largely uniform throughout the reactor, although possibly somewhat lower at the entrance to the reactor than it is at the exit of the reactor, by a few degrees. When feedstock or reactor temperature is referred to herein, that is a reference to the bulk temperature. Another temperature within the reactor, which typically differs from the bulk temperature, is the temperature at the site of the transfer of chlorine from HCI to hydrosilane. This is the temperature at the site of the reactive catalytic sites on the solid support. Typically, the temperature at these reactive sites, which will be referred to herein as the reactive site temperature, is many degrees hotter than the bulk temperature of the reactor. Further, as the reaction occurs at the gas to solid interface both the localized gas and solid temperatures can rise above the bulk gas and bulk catalyst temperature producing hotspots. Unless properly managed as described herein hotspots can potentially damage the catalyst. Basically, as heat dissipates from the reactive sites into the bulk gas flowing through the reactor, the bulk gas temperature will increase, and indeed it is this dissipation of heat from the catalytic sites that causes the temperature of the bulk gas in the reactor to be greater than the temperature of the bulk gas before it enters the reactor.

[0038] Temperature management is desirable for a variety reasons. For example, the chlorination reaction may proceed optimally in terms of HCI

consumption within a particular temperature range, where this range may depend on various factors such as the concentration of HCI in the feedstock, the flow rate through the reactor, the density of catalytic sites on the solid support within the reactor, etc. Some amount of routine trial-and-error will be needed to find this optimum range for a given set of reactor parameters and operating conditions, assuming the operator desires to practice the invention using optimum conditions. Temperature

management may also be desirable in order to extend the lifetime of the catalyst. Temperature may impact catalyst lifetime in a number of ways. For example, when the solid support for the catalytic sites is an organic polymer, that polymer will have a softening point which is desirably not exceeded during operation of the reactor.

Depending on the specific catalyst system employed, there is a maximum allowable exit temperature (too high and the catalyst may soften and flow into the retaining screen at the exit thus plugging the screen) and so provision must be made to control the temperature rise across the reactor due to the chlorination reaction or else the catalyst must be replaced frequently. Also, if the solid support softens too much, it may form a solid non-porous mass which will not only impede flow of the bulk gas through the reactor, but may also embed the reactive sites in plastic so they are no longer accessible to the reactive components of the bulk gas.

[0039] For the foregoing and other reasons, the present disclosure provides methods and systems for temperature management, that is, mechanisms for the control of the temperature within the reactor. Each of these methods and systems, which are described next, may be used singly or in any combination of two or three methods and systems to provide a desired temperature management within the reactor.

[0040] In one aspect, the feed to the reactor is cooled to a desired

temperature. This is a very effective means by which the reactor effluent temperature may be controlled because, for a given feed composition, the effluent temperature is a direct function of the feed temperature. In other words, and for a given amount of chlorination reaction, a proportional amount of heat will be released and the effluent temperature will be lesser or greater dependent on the temperature of the feed to the reactor. A lower feed temperature will result in a lower reactor effluent temperature.

[0041] Reaction rate within the reactor may be controlled by controlling the feed temperature to the reactor (a.k.a., "reactor feed cooling"). For example, if the reaction rate is undesirably fast within a given reactor, the feed temperature may be reduced. Because the reaction rate is lower at low temperature and higher at high temperature, this is an effective means of controlling the amount of reaction within a given reactor. However, there are limits as to how low one may wish to lower the feed temperature. For example, if the temperature is reduced too much then the feed to the reactor will partially condense resulting in two-phase flow to the reactor. Two- phase flow is undesirable because the catalyst system chlorinates most effectively when the reactants are in the vapor phase. This effect can be mitigated by placing a decanter immediately upstream of the reactor and removing the condensate, but this may be non-optimal because it increases capital cost (due to the need for more equipment). Further, the operating cost to cool reactor feed temperature must be considered. Lower temperature increases cooling cost. If two or more reactors are used in series (an option discussed below), then a cooling heat exchanger may be placed between each reactor and sufficient heat is removed from the product stream exiting the preceding reactor so that the temperature of the product stream exiting the following reactor is less than the maximum amount allowed.

[0042] Accordingly, in one aspect the present disclosure provides a chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction where the reactive site may optionally comprise nitrogen atoms;

b. providing first reactants at a first temperature, where the first temperature may be the temperature of the reactants as they exit a CVD reactor, the first reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the first reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si); c. cooling the first reactants to a second temperature, the second temperature being lower than the first temperature, where the second temperature may be below the temperature at which the reaction catalyst becomes thermally unstable, e.g., a temperature in the range of 25-100°C;

d. introducing the first reactants at the second temperature into the first reactor; and

e. contacting the first reactants with the reaction catalyst to provide first

products and to generate heat, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing Si (HChSi) which is lower than the first HChSi ratio, and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio.

[0043] Optionally, the temperature of the gas exiting the first reactor is monitored, where this exit temperature may be referred to as the third temperature. In one aspect of the disclosure, the third temperature is compared to a predetermined maximum temperature (a fourth temperature), and as the third temperature approaches or reaches this fourth temperature, cooling (or further cooling, as needed) is applied to the reactants so as to reduce the second temperature at which the reactants are introduced into the first reactor to a lower second temperature. In other words, the reactants are cooled to a lower temperature so that the temperature within the first reactor does not exceed the fourth temperature. Desirably, the second temperature is maintained above the dew point of the reactants and the products so that the reactants enter the first reactor entirely in the gas phase and the products leave the first reactor entirely in the gas phase. The dew point of the reactants is a function of the composition of the reactants as well as the pressure of the reactants. Also desirably, the reaction catalyst is an amine functionalized ion exchange resin, e.g., the catalyst has amine groups selected from amino, alkylamino and dialkylamino bonded to an organic polymer such as polystyrene that has been cross-linked with divinyl benzene. The fourth temperature is desirably selected to be below the softening point of the reaction catalyst, e.g., 25-100°C, or 25-90°C.

[0044] In another aspect, temperature management for the chlorination process is achieved by running the reactants through a series of reactors, with cooling of the gas occurring between the reactors. For example, a first reactor containing reaction catalyst may be fabricated or operated in such a way that the temperature rise within the reactor is modest, for instance, the temperature within the reactor does not exceed the softening point of the reaction catalyst, however incomplete conversion of the HCI takes place within the first reactor. Thus, a series of relatively small-sized reactors may be installed where the small size of each reactor limits the amount of reaction taking place within each reactor, thereby limiting the amount of conversion - and concomitant heat rise - within each reactor. This may be achieved, for example, by using a low concentration of catalyst within each of the

aforementioned reactors in a series of reactors, so that not all of the chlorine present as HCI is converted to chlorine present on a chlorosilane within the reactor. Under this scenario, the reactants enter a first reactor at a first temperature, or optionally after some cooling at a second temperature, and exit the reactor as the first products at a third temperature which is lower than the maximum desired temperature, i.e., a fourth temperature. Upon exiting the first reactor, the first products are cooled, for example with a heat exchanger, to a fifth temperature. The fifth temperature is lower than the third temperature, and is desirably above the dew point of the first products. The first products at the fifth temperature are then introduced into a second reactor which contains reaction catalyst, where the first products will exit the second reactor at a sixth temperature which is greater than the fifth temperature but preferably below the softening point of the reaction catalyst. The second products may be characterized by a lower HChSi molar ratio than the first products, and by a higher Si- CI:Si molar ratio than the first products. If the second product contains more HCI than is desired, the second products may likewise be cooled (this time to a seventh temperature, which will be lower than the sixth temperature) and then introduced into a third reactor which contains reaction catalyst in order to consume additional HCI. This process may be continued with fourth, fifth, etc. reactors until the HCI concentration in the final product has reached a desirably low level.

[0045] In summary, the present disclosure provides for more than one reactor in series where a cooling heat exchanger is placed between each reactor and sufficient heat is removed from the product stream exiting the preceding reactor so that the temperature of the product stream exiting the following reactor is less than the maximum preferred temperature. In other words, the chlorination reaction is performed in more than one reactor where the amount of chlorination performed in each reactor is controlled or limited such that the temperature rise across any given reactor is limited to less than the maximum amount allowed or desired. This is effective because temperature rise is directly proportional to the amount of chlorination that occurs during a given period of time. The amount of chlorination that occurs in a given reactor may be controlled by one or more means, e.g., two means (limiting the amount of catalyst and lowering the feed temperature to slow down the reaction), as discussed herein.

[0046] Accordingly, in one aspect the present disclosure provides a

chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which comprises nitrogen atoms, e.g., nitrogen bonded to hydrogen;

b. providing first reactants at a first temperature, the first reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the first reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si); c. optionally cooling the first reactants to a second temperature, which may be desirably done if the first temperature is the temperature at which the first reactants immediately exit a CVD reactor that is manufacturing polysilicon; d. introducing the first reactants into the first reactor;

e. contacting the first reactants with the reaction catalyst to provide first products upon exiting the first reactor and to generate heat, the first products characterized by a third temperature, a second molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the first HChSi ratio, and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI:Si) which is greater than the first Si-CI :Si ratio;

f. optionally monitoring the temperature (the third temperature) of the first products as they exit from the first reactor, and when the third temperature approaches a pre-determined maximum temperature (a fourth temperature), then the temperature (the second temperature) of the first reactants is decreased in order to decrease the third temperature;

g. cooling the first products to a fifth temperature, the fifth temperature being lower than the third temperature;

h. providing a second reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which comprises nitrogen atoms, e.g., nitrogen atoms bonded to hydrogen, where optionally the reaction catalyst in the second reactor is the same material as the reaction catalyst in the first reactor;

i. introducing the first products into the second reactor, and

j. contacting the first products with the reaction catalyst in the second reactor to provide second products upon exiting the second reactor and to generate heat, the second products characterized by a sixth temperature, a third molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the second HChSi ratio, and also characterized by a third molar ratio of Si- CI bonds to compounds containing silicon (Si-CI:Si) which is greater than the second Si-CI :Si ratio.

[0047] Optionally, this method which uses a series of two or more reactors with optional intermediate cooling (e.g., intermediate heat exchangers) may be used in conjunction with cooling of the reactants from a first temperature to a lower second temperature, as discussed previously. Desirably, each feedstock (e.g., the reactants, the first products, the second products, etc.) that enters a reactor is maintained above the dew point of the feedstock so that the feedstock enter a reactor entirely in the gas phase. Also desirably, the reaction catalyst is an amine functionalized ion exchange resin, e.g., the catalyst has amine groups selected from amino, alkylamino and dialkylamino bonded to an organic polymer, such as polystyrene that has been cross- linked with divinyl benzene.

[0048] In another aspect, temperature management for the chlorination process is achieved by removing heat from a reactor by means of cooling elements placed within the reactor, for example, internal cooling coils, where sufficient heat is removed to keep the temperature rise across the reactor to less than the maximum desired temperature. The skilled person is familiar with the introduction and operation of cooling coils to withdraw heat from a reactor. Optionally, the temperature of the gas exiting the reactor is monitored, where this exit temperature may be referred to as the third temperature. In one aspect of the disclosure, the third temperature is compared to a pre-determined maximum temperature (a fourth temperature), and as the third temperature approaches or reaches this fourth temperature, the cooling elements are operated so as to remove a greater amount of the generated heat. In other words, the gas within the reactor is cooled to a lower temperature so that the temperature within the reactor does not exceed the fourth temperature. Also desirably, the reaction catalyst is an amine functionalized ion exchange resin, e.g., the catalyst has amine groups selected from amino, alkylamino and dialkylamino bonded to an organic polymer such as polystyrene that has been cross-linked with divinyl benzene. The fourth temperature is desirably selected to be below the softening point of the reaction catalyst. [0049] Accordingly, in one aspect the present disclosure provides a

chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which may optionally comprise nitrogen atoms, the first reactor also comprising internal cooling elements;

b. providing reactants at a first temperature, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si);

c. introducing the reactants into the first reactor;

d. contacting the reactants with the solid support to provide first products upon exiting the first reactor and to generate heat, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the first HChSi ratio, and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio; and

e. withdrawing at least some of the heat from the first reactor by operation of the cooling elements.

[0050] In one aspect, feedstock enters the reactor at more than one reactor location, and the amount of feedstock entering the reactor at each location is adjusted as needed in order to control the temperature within the reactor. This is especially helpful in the case where one is bypassing supplemental HCI. In this case, where there is only one combined feedstock, this does not alter the resultant temperature for a given amount of conversion - although it may be a way of limiting conversion in this instance within a given reactor. In the latter case it mitigates the potential for hot spots within the reactor. However, in the latter case one can control the temperature at each stage of addition if there is internal cooling between or within the stages. This method is referred to herein as reactor feed by-passing. Reactor feed by-passing may be used to control the amount of chlorination reaction within a given reactor or within a series of such reactors. Reactor feed by-passing refers to separating a portion of the feed to a reactor from the main feed and introducing that portion (or a portion thereof) part way down the given reactor through a different entrance port. This method reduces the effective hold-up time within the reactor. Since the amount of reaction within a given reactor is a function of hold up time within the reactor, the amount of reaction within a given reactor can be reduced by by-passing a greater amount of the feed and, as a result, the temperature rise across the reactor can therefore be reduced, at least when bypassing a portion of the combined feed stream. When bypassing supplemental HCI however, and assuming the conversion of HCI to chlorosilane is 100% within a reactor, and cooling is introduced between zones of a reactor then the reactor temperature can be limited to less than the softening point of the reaction catalyst. Feed by-passing requires that a bypass control valve be installed on the main feed stream to the reactor and that one or more side-feed ports be installed on the reactor shell (e.g., half way down the side of the reactor). Each side feed-port may be equipped with a gas distributor inside the reactor to help ensure good mixing of the bypass stream with the main stream passing through the reactor. Each of the places where feed (reactants) may be introduced into the reactor may be referred to as an entrance port. The reactor will typically have a single exit port, however multiple exit ports may also be installed along the reactor to allow product to be withdrawn from the reactor at more than one location, thus also providing a control on hold up time. In the case where the reactor has only a single exit port, then feed that enters at a location furthest from the exit port will have the longest hold up time, while feed that enters relatively closer to the exit port will have a shorter hold up time.

[0051] Accordingly, in one aspect the present disclosure provides a chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which comprises nitrogen atoms, the first reactor also comprising more than one entrance port through which reactants may be introduced into the first reactor;

c. introducing the reactants into both a first and second entrance port of the first reactor, reactants entering the first entrance port having a longer hold up time within the first reactor than reactants which enter the second entrance port; and

d. contacting the reactants with the reaction catalyst to provide first products upon exiting the first reactor and to generate heat, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the first HChSi ratio, and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio.

[0052] Optionally, the process as just described, which makes use of more than one entrance port to introduce reactant feedstock into a chlorination reactor, may be operated in conjunction with one or more additional temperature management methods, e.g., the methods described herein, including cooling the feedstock before it enters a chlorination reactor, running the feedstock through a series of chlorination reactors with the products exiting one reactor being cooled prior to becoming a reactant for the next reactor in the series, using cooling coils located in a chlorination reactor to absorb heat, and, as discussed next, adjusting the composition of the feedstock to a reactor.

[0053] In another aspect, temperature management for the chlorination process is achieved by altering or adjusting the composition of the reactants prior to entry of the reactants into the chlorination reactor. This may be particularly relevant in the case where the off gas from a CVD reactor provides the reactants for the chlorination reaction, and that off gas has a higher than desired concentration of HCI. For example, the concentration of the HCI in the reactant may be reduced by adding a diluent to the reactant, to thereby form a diluted reactant. As the concentration of the HCI in the reactant is reduced, the temperature increase within the reactor will decrease, all other factors being constant, since the diluent acts as a heat sink.

Suitable diluents are preferably in the gas phase at the temperature at which the reactant is introduced into the reactor. Exemplary diluents meeting this criteria are hydrogen, silane, monochlorosilane, dichlorosilane, trichlorosilane and

tetrachlorosilane, depending on the temperature and pressure of the reactant.

Suitable diluents may be inert to the reaction conditions within the reactor, i.e., the diluent does not react with the catalyst or with any component of the reactant.

Exemplary diluents meeting this criteria are hydrogen ( H2), nitrogen (N2) and argon. Suitable diluents are preferably either easy to remove from the product or do not need to be removed from the product. Again, hydrogen (H2) and tetrachlorosilane are two examples that meet this criteria. Thus, temperature management may be achieved when the composition of the reactants is altered prior to entry of the reactants into the reactor, e.g., by adding an inert diluent such as hydrogen ( H2).

[0054] Accordingly, in one aspect the present disclosure provides a chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to a reactive site for a chlorination reaction which comprises nitrogen atoms;

b. providing reactants having a first composition and a first temperature, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si); c. combining the reactants with a diluent to provide a diluted reactant, wherein the diluted reactant is characterized by a second concentration of hydrogen chloride, the second concentration of hydrogen chloride being less than the first concentration of hydrogen chloride, and the diluted reactant is further characterized by a second molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si);

d. introducing the diluted reactant into the first reactor;

e. contacting the diluted reactant with the reaction catalyst to provide first

products upon exiting the first reactor and to generate heat, the first products characterized by a third molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the second HChSi ratio, and also characterized by a third molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the second Si-CI :Si ratio.

[0055] Optionally, the process as just described, which makes use of a diluent to moderate the heat generated in the reactor, may be operated in conjunction with one or more additional temperature management methods, e.g., any of the methods described herein. For example, in addition to adding a diluent to the reactants to provide a diluted reactant, either one or both of the reactants or the diluted reactants may be cooled to a second temperature, the second temperature being lower than a first temperature, which is the temperature of the reactants or the diluted reactants. As another example, the diluted reactants may be run through a series of reactors, optionally with cooling occurring between any two reactors.

[0056] In another aspect, temperature management for the chlorination process is achieved by staged addition of HCI to a hydrosilane-containing composition. This aspect is particularly relevant in the case where it is desired to increase the molar ratio of X-CI bonds to compounds containing X in a composition, i.e., to increase the X- CI:X molar ratio in a composition, where X is optionally Si. As discussed elsewhere herein, this situation arises, e.g., in certain monosilane decompositions processes as described in PCT publication no. WO 2011/084427. Staged addition refers to adding HCI to a flowing gas or liquid stream, e.g., a hydrosilane-containing composition, where the HCI is added at different locations along the stream. For example, a hydrosilane-containing composition may flow through a long tube that contains reaction catalyst, and HCI is added at various locations spaced along the length of the tube. For example, HCI may be introduced at the inlet of the tube, and also at a point intermediate the inlet and outlet of the tube, where this option provides for a two- stage addition of HCI. Additional inlets for HCI may be located along the length of the reactor, providing for three-stage, four-stage, five-stage etc. addition of HCI to the hydrosilane-containing composition. In this way, an increase in the X-CI:X molar ratio of the composition occurs gradually along the length of the reactor, allowing for relatively modest heat generation along the reactor, with an opportunity for heat dissipation and/or active heat removal to occur so that the temperature within the reactor does not exceed the temperature at which the reaction catalyst become unstable.

[0057] Optionally, the process as just described, which makes use of a staged addition of HCI to moderate the heat generated in the reactor, may be operated in conjunction with one or more additional temperature management methods, e.g., any of the methods described herein. For example, in addition to staging the addition of HCI, a diluent (where the diluent would not be HCI but may be one or more other species as described elsewhere herein) may be added to the reactant to provide a diluted reactant; and either one or both of the reactants or the diluted reactants may be cooled to a second temperature, the second temperature being lower than a first temperature. As another example, the diluted reactant may be run through a series of reactors, optionally with cooling occurring between any two reactors, where staged addition of HCI may occur at any one or more of the series of reactors.

[0058] To reiterate, the aforementioned temperature control methods can be implemented singly or in combination. Together these methods provide a highly effective means of controlling the temperature rise across a given reactor or, as discussed above, series of reactors within pre-determined limits. SYSTEM DESIGN AN D OPERATION

[0059] In one aspect, the present disclosure provides a system for performing the process previously described. For example, the present disclosure provides a system comprising a first reactor, the first reactor comprising: (a) a solid support, the solid support comprising nitrogen atoms bonded to the solid support in the form of amino or dialkylamino (e.g., dimethylamino) groups; (b) a gas phase atmosphere in contact with the solid support, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane,

monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si- CI:Si); and (c) a temperature within the first reactor, the temperature in excess of the dew point of the mixture.

[0060] The system may comprise a cooling unit, for example a heat exchanger or a chiller, which in operation may be used to decrease the temperature of the reactant to a pre-determined temperature. In addition, or alternatively, the system may comprise a source of diluent, e.g., a tank of diluent, which is in fluid

communication with the reactor or the conduit to the reactor through which the reactant enters the reactor. The cooling element, when present, may be positioned to act on either or both of the reactant or the diluted reactant.

[0061] The system may comprise a second reactor in fluid communication with the first reactor. The second reactor comprises: (a) a solid support, the solid support comprising nitrogen atoms bonded to the solid support in the form of amino or dialkylamino groups, e.g., dimethyl amino groups; ( b) a gas phase atmosphere in contact with the solid support, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane,

monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si- CI:Si); and (c) a temperature within the second reactor, the temperature in excess of the dew point of each of the mixture of the reactants at system pressure and the mixture of the products at system pressure. Optionally, the reaction catalyst present in the first reactor is identical to the reaction catalyst present in second reactor.

Optionally, the product from the first reactor is used as the reactant in the second reactor, and accordingly the ratio of hydrogen chloride to compounds containing Si (HChSi) in the feed to the first reactor is greater than the ratio of hydrogen chloride to compounds containing Si (HChSi) in the feed to the second reactor, and the ratio of Si- Cl bonds to compounds containing silicon (Si-ChSi)in the feed to the first reactor is less than the ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) in the feed to the second reactor.

[0062] In one aspect, a cooling unit is positioned between the first and second reactors, the cooling unit cooling the product from the first reactor, before that product is utilized as a reactant in the second reactor. For example, in the case where it is desirable that the temperature within a reactor does not exceed 85°C (which is the softening temperature of a typical poly(styrene-divinyl benzene) solid support), one way to accomplish this is to monitor the exit temperature from the first reactor (i.e., the 3^rd temperature) and adjust the temperature of the reactants to the first reactor (i.e., the 2^nd temperature) such that the exit temperature does not exceed 85°C (an exemplary 4^th temperature). In the case where the HCI reaction is not complete, then the product from the first reactor may be cooled to a 5^th temperature and fed into a second reactor. Again, the exit temperature of the second reactor (i.e., the 6^th temperature) may be monitored and the 5^th temperature adjusted such that the 6^th temperature does not exceed 85°C, and so on until all or essentially all of the HCI is reacted.

[0063] A plant that operates a CVD reactor for polysilicon production may, and typically does, have multiple CVD reactors wherein the deposition process is performed. In normal plant operation, most and perhaps all of these CVD reactors will be producing polysilicon, and each CVD reactor that is producing polysilicon will also create an off gas. The off gas will typically contain about 1% HCI in addition to hydrogen, hydrosilanes and STC. Each off gas is typically fed into a single off gas recovery system where the off gas components are separated. Routinely, CVD reactors are shut down and the polysilicon is collected. Upon starting back up, it is typically observed that the off gas from a CVD reactor contains more than the steady- state amount of HCI, perhaps as much as 3-5% HCI compared to the steady-state HCI concentration of 1%. Accordingly, when one or more CVD reactors are started up, the collective off gas from the total of the actively running CVD reactors will show an increase in the concentration of HCI. Therefore, when the process of the present disclosure, which utilizes a reactor holding amine-containing reaction catalyst to transfer chloride from HCI to a hydrosilane, is used to remove HCI, or at least reduce the concentration of HCI in the off gas, there will typically be more heat generation within the reactor during CVD reactor start-up than during steady-state operation of the plant. This extra heat generation may, if unmanaged, damage the reaction catalyst since the reaction catalyst may be unstable at temperatures above about 80°C. To maintain the stability of the reaction catalyst during CVD reactor start-up, temperature management as disclosed herein may be employed.

[0064] Accordingly, it should be recognized that one embodiment of the present disclosure is a system comprising a CVD reactor, e.g., one that is designed to perform the Siemens process that forms polysilicon, which creates an off gas that is fed into the reactor containing a reaction catalyst as described herein. Thus, in one embodiment the present disclosure provides: a system comprising a first reactor that produces polysilicon and generates an off -gas, the off-gas comprising HCI and hydrosilane, and a second reactor in fluid communication with the first reactor, the second reactor containing a reaction catalyst comprising a solid support bonded to nitrogen atoms as disclosed herein, the second reactor receiving some or all of the off -gas from the first reactor and forming a product which exits the second reactor. Optionally, the off gas may be referred to as the reactants, and may comprise hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the off gas characterized by a first molar ratio of hydrogen chloride to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI:Si). The products may be characterized by a second molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the first HChSi ratio, and also

characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio. The system may optionally further comprise temperature monitoring means, e.g., a thermocouple, in order to determine the temperature within the second reactor. Also optionally, the system may further comprise temperature management means, such as those described herein, e.g., a heat exchanger, which may be used to maintain the temperature within the second reactor below a temperature which is harmful to the functional integrity of the reaction catalyst. The first reactor may be a chemical vapor deposition (CVD) reactor.

[0065] As some further illustrations of temperature management, the collective off -gas from the CVD reactor(s) in steady-state operation, which has a HCI

concentration of about 1%, may be cooled to a temperature of about 60°C and then allowed to enter a chlorination reactor having a reaction catalyst as disclosed herein. The temperature rise as the HCI is consumed and more highly chlorinated silicon species are formed, will be on the order of 10-15°C, or about 13°C. In this situation, the catalyst is exposed to a temperature of about 75°C, which in the case where the catalyst is AMBERLYST™ A-21, is a sufficiently low temperature that the catalyst will retain its efficacy. Accordingly, for AMBERLYST™ A-21, a gas inlet temperature of about 70°C or less should be suitable. In the event that it is desired to employ a gas inlet temperature which, after the temperature rise caused by the chlorination reaction, would generate a temperature within the chlorination reactor which is harmful to the integrity of the catalyst, one option is to add a diluent to the off gas. For example, if hydrogen is added to the off gas, the concentration of HCI in the off gas will be reduced, and so the rate of heat generation due to the chlorination reaction will be reduced. This allows time for the excess heat to escape or be actively removed, e.g., with a heat exchanger, from the reactor, so that the temperature rise within the reactor is managed to not exceed a temperature that is harmful to the catalyst.

[0066] In the event that it is desired to form more of the highly chlorinated silicon species than can be formed by reaction of all of the HCI in the CVD off gas, then additional HCI may be added to the chlorination reactor. The addition of HCI to the CVD off gas will cause more heat to be generated within the chlorination reactor, and the impact of this additional heat on the integrity of the reaction catalyst must be considered. If the off gas inlet temperature is 60°C, and the catalyst has good stability up to about 85°C, then some amount of HCI may be added to the off gas to provide a HCI concentration in excess of 1% without damaging the catalyst. For precautions sake, the temperature of the off gas may be reduced to below 60°C, however it is desirable that the temperature of the off gas entering the chlorination reactor be at least about 5°C in excess of the dew point of the off gas, at the pressure employed. As an additional or alternative precaution, a diluent may be added to the off gas. For example, both hydrogen (which may function as a diluent) and HCI (which does not function as a diluent but will function as a reactant) may be added to the CVD off gas in order that the additional heat generated by the additional HCI does not cause damage to the reaction catalyst.

[0067] In addition to, or alternatively to, the use of lower off gas inlet temperature and dilution of the off gas with, e.g., hydrogen, the following options may be used for temperature management: a) a cooling coil may be placed within the chlorination reactor to draw heat from the reactor, for example, i) a single coil may run along all or a portion of the interior length of the chlorination reactor; ii) the reaction catalyst may be placed into zones spaced along the length of the reactor, and a cooling coil may be positioned between any two neighboring zones.; b) a single large chlorination reactor may be replaced with two or more smaller chlorination reactors operating in tandem, where i) cooling may optionally be applied to the gas exiting an upstream chlorination reactor before that gas enters the next (downstream) chlorination reactor; ii) diluent may be added to the gas stream prior to that gas stream entering any one or more of the smaller chlorination reactors. At any point along these systems, HCI may be introduced to the gas stream, in the event that it is desired to create more of the highly chlorinated silanes than would otherwise form due to the presence of the HCI that is naturally present in the CVD reactor off -gas. TECH NOLOGY APPLICATIONS

[0068] The chlorination process of the present disclosure provides at least two important benefits. The first is due to reacting undesirable HCI in an off -gas, essentially to extinction. This enables significant capital and operating cost reductions when the off -gas comes from a chemical vapor deposition (CVD) reaction for polysilicon manufacture. This reduction in capital and operating costs is due to the fact that when HCI is fully converted to chlorosilane, it is no longer necessary to physically remove and sequester the highly volatile HCI as a gas or as a liquid. In current practice, HCI is typically removed from hydrogen recycle to the CVD reactor by means of absorption into refrigerated liquid chlorosilane streams. Due to the low temperature required for effective absorption (e.g., minus 50°C), this operational step is complex and costly to install and operate. HCI removal from hydrogen recycle is important because HCI in hydrogen recycle to the CVD reactor is detrimental to efficient and proper operation of the CVD reactor.

[0069] The second important benefit afforded by the process of the present disclosure is that it increases the chlorine content in a closed system. For certain monosilane decomposition processes (see, e.g., PCT publication no. WO 2011/084427) it is desirable to provide a means whereby the chlorine content of the chlorosilane recycle stream to the CVD system may be increased. An optimal means is to react make-up HCI gas, from an outside source, with the chlorosilane recycle stream in order to generate more highly chlorinated silane species. The process of the present disclosure provides an efficient means to increase the chlorine content of the chlorosilane recycle stream. Increase may be achieved by adding HCI gas to the CVD off -gas stream and then feeding the resultant mixture to the chlorination reactor of the present disclosure. This step may require an additional temperature control mechanism operating apart or in conjunction with the temperature control mechanism described previously. For example, the reactor feed cooling method may be employed to the HCI gas in addition to the other reactants. Also, reactor by-passing may be employed, although in this instance the by-passing is of the make-up HCI stream where portions of the make-up HCI stream are added to the feed to each of two or more reactors in series. For example, one-third or one-half of the HCI makeup may be added to one of three or one of two reactors, respectively, in series.

[0070] The process and system of the present disclosure optionally provides an advantageous means to convert HCI in CVD off -gas to chlorosilanes by reaction with SihU, S1 H3CI, S1H2CI2, and/or S1 HCI3 to simplify the off-gas treatment system whose purpose is to separate a hydrogen gas stream for recycle to the Siemens CVD reaction step and to separate the chlorosilanes as S1 H2CI2, S1 HCI3, and SiC for recycle to the CVD reaction step (in the case of S1 H2CI2 and S1HCI3); or to a hydrochlorination reaction step.

[0071] The process and system of the present disclosure optionally provides an advantageous means to maintain and/or adjust the chlorine balance in a system by reacting HCI with S1H4, S1 H 2CI2, or S1HCI3, especially where the HCI is in very pure form so that the resultant higher chlorinated silane may be recycled to a CVD step creating high purity polysilicon.

[0072] The process and system of the present disclosure optionally provides an advantageous means to convert low boiling boron or phosphorus impurities (like PH3 or B2H6) to higher boiling impurities (like PCI3 or BCI3) so that separation form desired chemicals (like SiCU) may be more easily effected.

[0073] The present disclosure provides the following em bodiments, which are exemplary of the inventive em bodiments disclosed herein:

1) A chlorination process comprising:

a. providing a reactor containing reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to nitrogen atoms; b. introducing reactants to the reactor, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first ratio of Si-CI bonds to silicon compounds (Si-CI :Si); c. contacting the reactants with the solid support to provide products, the products characterized in comparison to the products as having a lower HChSi ratio and a higher Si-CI :Si ratio.

) The process of embodiment 1 wherein the solid support is an organic polymer.) The process of embodiment 2 wherein the solid support is polystyrene that has been cross-linked with divinyl benzene.

) The process of embodiment 1 wherein the nitrogen atoms are provided by a functional group selected from amino, alkylamino, and dialkylamino.

) The process of embodiment 4 wherein the functional groups are

dimethylamino.

) The process of embodiment 1 wherein the solid support is a weak base anion exchange resin.

) The process of embodiment 1 wherein the solid support is conditioned prior to step b, the conditioning comprising dehydrating the solid support.

) The process of embodiment 7 wherein hot gas selected from hydrogen ( H2) and nitrogen ( N2) is passed through the solid support in order to dehydrate the solid support.

) The process of embodiment of embodiment 1 wherein the solid support is conditioned prior to step b, the conditioning comprising exposing the solid support to gaseous chlorosilane in the absence of hydrogen chloride.

0) The process of embodiment 1 wherein the reactants that enter the reactor, and the products that exit the reactor, and the silicon compounds within the reactor, are all in the gas phase.

1) The process of embodiment 1 wherein the reactor operates at a reaction temperature, the reaction temperature being in the range of 25-100°C.

2) The process of embodiment 1 wherein the temperature of the products as they exit the reactor (the second temperature) is monitored, and when the second temperature approaches a pre-determined maximum temperature, the temperature of the reactants to the reactor is decreased so as to decrease the second temperature. ) The process of embodiment 1 wherein the temperature of the products as they exit the reactor (the second temperature) is monitored, and when the second temperature approaches a pre-determined minimum temperature, the hydrogen chloride content of the reactants is increased so as to increase the second temperature.

) The process of embodiment 1, wherein the products from the reactor (the first products) comprise hydrogen chloride and hydrochlorosilane, and the first products are introduced as reactants to a second reactor, to provide products from the second reactor (the second products).

) A system comprising a first reactor, the first reactor comprising:

a. a solid support, the solid support comprising nitrogen atoms bonded to the solid support;

b. a gas phase atmosphere in contact with the solid support, the

atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane,

monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first ratio of Si-CI bonds to silicon compounds (Si-CI :Si);

c. a temperature within the first reactor, the temperature in excess of the boiling point of the each of the silicon compounds.

) The system of embodiment 15 further comprising a second reactor, the second reactor comprising:

b. a gas phase atmosphere in contact with the solid support, the

c. a temperature within the second reactor, the temperature in excess of the boiling point of the each of the silicon compounds.

17) The system of embodiment 16 wherein a cooling unit is positioned between the first and second reactors, the cooling unit cooling the product from the first reactor, before that product is utilized as a reactant in the second reactor.

18) A chlorination process comprising:

a. providing a reactor comprising a solid support, the solid support

comprising nitrogen atoms;

b. introducing reactants to the reactor, the reactants comprising hydrogen chloride and at least one compound having an X-H bond where X is an atom selected from the atoms of Group I II, Group IV and Group V of the periodic table, the reactants characterized by a first ratio of hydrogen chloride to compounds having X-H bonds (HCI:X) and also characterized by a first ratio of X-CI bonds to compounds having X-H bonds (X-CI:X); c. contacting the reactants with the solid support to provide products, the products characterized in comparison to the products as having a lower HCI:X ratio and a higher X-CI:X ratio.

[0074] The Examples provided hereafter further illustrate and exemplify the systems and methods of the present invention. The values in the Examples are based on models. It is to be understood that the scope of the present invention is not limited in any way by the scope of the following Examples.

[0075] In the following Examples, reference is made to Figure 1. In Figure 1, stream #1 (SI) represents the off gas or outlet gas from a typical CVD reactor that produces polysilicon from trichlorosilane, e.g., the Siemens process, after that off gas has been cooled down through a combination of heat recovery and utility cooling. This is a preferred feedstock to the off gas treatment system of the present invention. Stream #2 (S2) represents an alternate feed stream which provides for supplemental hydrogen chloride addition to the reactor, system and method of the present disclosure, i.e., S2 represents hydrogen chloride. This hydrogen chloride of S2 is in addition to the hydrogen chloride already present in the off gas or outlet gas from a typical TCS CVD reactor (not shown). Stream #3 (S3) represents the portion of stream #2 (S2) that is sent to the first chlorination reactor labeled RX1. Stream #4 (S4) represents the combination of stream #1 (SI), optional stream #3 (S3) and optional stream #10 (SIO). S4 becomes the feedstock to the first reactor containing the reaction catalyst as described herein, labeled RX1. Stream #5 (S5) represents the outlet or product of the first reactor labeled RX1 and is the feedstock to the cooler labeled HX1. Stream #6 (S6) represents the outlet or product of the cooler labeled HX6. Optional stream #7 (S7) represents the optional portion of optional stream #2 (S2) that is sent to the second chlorinator reactor labeled RX2. Stream #8 (S8) represents the combination of stream #6 (S6) and optional stream #7 (S7) and is the feedstock to the second reactor labeled RX2. Stream #9 (S9) represents the outlet or product of the second reactor labeled RX2. Stream #10 (S10) represents a hydrogen recycle stream, where S10 is an optional feature. S10 is hydrogen gas that is optionally separated from S9 by unit operations that are not shown, and then returned to the start of the process to be mixed with SI and S3. Ql represents energy drawn from the system due to reducing the temperature of S5 via the heat exchanger HX1. Ml and M2 represent first and second mixers for mixing together two or more gas or liquid streams to provide a single stream that enters RX1 or RX2. SP1 is a splitter that divides a single stream S2 into two streams S3 and S7.

EXAMPLES

Example 1: Reactor feed cooling

[0076] Tables 1, 2, 3 and 4 illustrate the use of a temperature control mechanism to provide temperature control for the process of the present disclosure, as described above. These tables show that for a given CVD off-gas stream (Stream SI) as the first reactor feed temperature is increased from 50°C (Table 4) to 70°C (Table 2) the first reactor effluent temperature (Stream 5) increases from 62.9°C to 82.7°C which is within acceptable limits. However when the feed temperature of Stream SI is further increased to 80°C (Table 1) the first reactor effluent temperature increases to

92.7°C. Because 92.7°C may exceed the maximum pre-determined temperature

within the reactor, the control scheme in this case would control the first reactor feed temperature at 70°C, because this minimizes cooling cost while maintaining the first reactor effluent temperature within allowable limits.

[0077] Accordingly, by cooling the feed to a given reactor, the temperature

within the reactor may be maintained within specified boundaries. A lower feed

temperature will result in a lower reactor effluent temperature, i.e., a lower

temperature within a reactor. This method may be used in conjunction with more

than one reactor in series where a cooling heat exchanger may be placed between

each reactor and sufficient heat is removed from the product stream exiting the

preceding reactor so that the temperature of the product stream exiting the following reactor is less than the maximum desired temperature.

Table 1

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 80.0 80.0 80.0 80.0 92.7 60.0 80.0 60.0 59.8

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.20 47.20 47.20 36.46 47.20 47.20

Mass Flow (kg/h) 39000 0 0 39000 39000 39000 0 39000 39000

Mole Flow (kgmole/h) 826.2 0 0 826.2 826.2 826.2 0 826.2 826.2

Fraction

H drogen 0.685 0 0 0.685 0.692 0.692 0 0.692 0.692

Hydrogen chloride 0.007 1.000 1.000 0.007 0 0 1.000 0 0

Dichlorosilane 0.016 0 0 0.016 0.009 0.009 0 0.009 0.009

Trichlorosilane 0.162 0 0 0.162 0.170 0.170 0 0.170 0.170

Silicon tetrachloride 0.129 0 0 0.129 0.129 0.129 0 0.129 0.129

Table 2

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 70.0 70.0 70.0 70.0 82.7 60.0 70.0 60.0 59.8

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.20 47.20 47.20 36.46 47.20 47.20

Mass Flow (kg/h) 39000 0 0 39000 39000 39000 0 39000 39000

Mole Flow (kgmole/h) 826.2 0 0 826.2 826.2 826.2 0 826.2 826.2

Fraction

Hydrogen 0.685 0 0 0.685 0.692 0.692 0 0.692 0.692

Hydrogen chloride 0.007 1.000 1.000 0.007 0 0 1.000 0 0 Dichlorosilane 0.016 0 0 0.016 0.009 0.009 0 0.009 0.009

Trichlorosilane 0.162 0 0 0.162 0.170 0.170 0 0.170 0.170

Silicon tetrachloride 0.129 0 0 0.129 0.129 0.129 0 0.129 0.129

Table 3

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 60.0 72.8 60.0 60.0 60.0 59.8

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.20 47.20 47.20 36.46 47.20 47.20

Mass Flow (kg/h) 39000 0 0 39000 39000 39000 0 39000 39000

Mole Flow (kgmole/h) 826.2 0 0 826.2 826.2 826.2 0 826.2 826.2

Fraction

Hydrogen 0.685 0 0 0.685 0.692 0.692 0 0.692 0.692

Hydrogen chloride 0.007 1.000 1.000 0.007 0 0 1.000 0 0

Dichlorosilane 0.016 0 0 0.016 0.009 0.009 0 0.009 0.009

Trichlorosilane 0.162 0 0 0.162 0.170 0.170 0 0.170 0.170

Silicon tetrachloride 0.129 0 0 0.129 0.129 0.129 0 0.129 0.129

Table 4

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 50.0 50.0 50.0 50.0 62.9 60.0 50.0 60.0 59.8

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.20 47.20 47.20 36.46 47.20 47.20

Mass Flow (kg/h) 39000 0 0 39000 39000 39000 0 39000 39000

Mole Flow (kgmole/h) 826.2 0 0 826.2 826.2 826.2 0 826.2 826.2

Fraction

Hydrogen 0.685 0 0 0.685 0.692 0.692 0 0.692 0.692

Hydrogen chloride 0.007 1.000 1.000 0.007 0 0 1.000 0 0

Dichlorosilane 0.016 0 0 0.016 0.009 0.009 0 0.009 0.009

Trichlorosilane 0.162 0 0 0.162 0.170 0.170 0 0.170 0.170

Silicon tetrachloride 0.129 0 0 0.129 0.129 0.129 0 0.129 0.129

Example 2: Make-up HCI reactor bypassing

[0078] Tables 5, 6 and 7 illustrate the use of a temperature control mechanism described above, where the chlorine content in a feedstock is adjusted in order to

control the operating temperature within the reactor into which the feedstock is

introduced. These tables show that, for a given CVD off -gas stream (Stream SI) and

for a given first reactor feed temperature, when the make-up HCI is added (compare

Table 3 and Table 5) the first reactor effluent temperature is increased from 72.8°C to 85.5°C. When 85°C is below the maximum desired pre-determined temperature

within the reaction, the feed temperature control scheme would set the feed

temperature to the first reactor at 60°C (which is the first reactor feed temperature for both Table 3and 5). Table 6 shows that the amount of make-up HCI to the system can be doubled, compared to Table 5, without exceeding 90°C in the effluent stream from the second reactor (Stream S9) by feeding half of the total make-up HCI to the first reactor and the remainder to the second reactor, where the first reactor effluent is cooled from 85.5°C down to 60°C in a cooler (heat exchanger) located between the first and second reactors. In Table 6the control scheme would divert half of the total make-up HCI from the first reactor to the second reactor, cool the CVD off -gas stream (Stream SI) feeding the first reactor to 60°C, and cool the effluent leaving the second reactor (Stream S5) to a temperature equal to or slightly greater than 60°C. Table 7 compared to Table 6 shows that even more HCI may be added to the second reactor (i.e., double the amount added in Table 6) without exceeding a pre-determined

maximum reactor temperature of 90°C. In Table 7, the first reactor effluent is cooled to 60°C (Stream S6), and second reactor effluent (Stream S9) temperature rises to

82.7°C.

[0079] Accordingly, the staged addition of HCI makeup gas to a CVD off gas, prior to entry of the combined gases into a chlorination reactor as disclosed herein, is an effective means of adjusting the operating temperature within the chlorination reactor. In one aspect, the present disclosure provides a temperature control

mechanism wherein HCI makeup is added to a CVD off-gas to provide a feedstock, and the temperature of the feedstock is adjusted in concert with monitoring the

temperature of the product gas exiting the chlorination reactor, where this

temperature control mechanism maintains the temperature within the reactor

between minimum and maximum pre-determined temperatures. In another aspect, HCI makeup addition is staged between two or more reactors, where this staging when combined with inter-stage cooling maintains the temperature within each

reactor between minimum and maximum pre-determined temperatures.

Table 5

SI S2 S3 S4 S5 S6 S7 S8 S9 VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 60.0 85.5 60.0 60.0 60.0 59.8

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.12 47.12 47.12 36.46 47.12 47.12

Mass Flow (kg/h) 39000 218.8 218.8 39218 39218 39218 0 39218 39218

Mole Flow (kgmole/h) 826.2 6.00 6.00 832.2 832.2 832.2 0 832.2 832.2

Fraction

Hydrogen 0.685 0 0 0.680 0.695 0.695 0 0.695 0.695

Hydrogen chloride 0.007 1.000 1.000 0.014 0 0 1.000 0 0

Dichlorosilane 0.016 0 0 0.016 0.002 0.002 0 0.002 0.002

Trichlorosilane 0.162 0 0 0.161 0.176 0.176 0 0.176 0.176

Silicon tetrachloride 0.129 0 0 0.128 0.128 0.128 0 0.128 0.128

Table 6

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 60.0 85.5 60.0 60.0 60.0 71.6

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.12 47.12 47.12 36.46 47.05 47.05

Mass Flow (kg/h) 39000 437.5 218.8 39218 39218 39218 218.8 39437 39437

Mole Flow (kgmole/h) 826.2 12.00 6.00 832.2 832.2 832.2 6.00 838.2 838.2

Fraction

Hydrogen 0.685 0 0 0.680 0.695 0.695 0 0.690 0.697

Hydrogen chloride 0.007 1.000 1.000 0.014 0 0 1.000 0.007 0

Dichlorosilane 0.016 0 0 0.016 0.002 0.002 0 0.002 0

Trichlorosilane 0.162 0 0 0.161 0.176 0.176 0 0.174 0.171

Silicon tetrachloride 0.129 0 0 0.128 0.128 0.128 0 0.127 0.132

Table 7

SI S2 S3 S4 S5 S6 S7 S8 S9

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 60.0 85.5 60.0 60.0 60.0 82.7

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00

Mole Weight 47.20 36.46 36.46 47.12 47.12 47.12 36.46 46.97 46.97

Mass Flow (kg/h) 39000 656.3 218.8 39218 39218 39218 437.5 39656 39656

Mole Flow (kgmole/h) 826.2 18.00 6.00 832.2 832.2 832.2 12.00 844.2 844.2

Fraction

Hydrogen 0.685 0 0 0.680 0.695 0.695 0 0.685 0.699

Hydrogen chloride 0.007 1.000 1.000 0.014 0 0 1.000 0.014 0

Dichlorosilane 0.016 0 0 0.016 0.002 0.002 0 0.002 0

Trichlorosilane 0.162 0 0 0.161 0.176 0.176 0 0.173 0.162

Silicon tetrachloride 0.129 0 0 0.128 0.128 0.128 0 0.126 0.139

Example 3: Make-up hydrogen to dilute reactant HCI

[0080] Tables 8 and 9 illustrate the use of a temperature control mechanism described above, where the chlorine content in a feedstock is adjusted in order to

introduced. Table 8 shows the case where the reactant has 0.93 mol% hydrogen

chloride and 71.37 mol% hydrogen, and are introduced into the reactor at 5 barg

pressure and 60°C temperature. After essentially complete transfer of chloride from

hydrogen chloride to chlorosilane, the increase in temperature is 17.2°C, i.e., the exit

temperature of the products is 77.2°C. This calculation does not take into account

possible redistribution reactions which may occur, and which may cause an additional increase of lor 2 degrees in temperature. This calculation assumes that hydrogen

chloride reacts with DCS much faster than it reacts with TCS. Table 9 shows the case

where hydrogen has been added to the reactants of Table 8, so as to increase the

hydrogen to hydrogen chloride ratio of the reactants and thereby provide for diluted

reactants. In this case, the diluted reactant has 0.76 mol% hydrogen chloride and

76.41mole% hydrogen. The diluted reactant is introduced to the reactor under the

same operating conditions as were used in the case illustrated in Table 8, i.e., at 5 barg pressure and 60°C temperature. In this case, after essentially complete transfer of

chloride from hydrogen chloride to chlorosilane, the increase in temperature is 14.9°C, i.e., the exit temperature of the products is 74.9°C. Accordingly, by diluting the

hydrogen chloride, with a 30% increase in hydrogen content, the temperature rise

across the reactor has been reduced by 2.3°C. Furthermore, the dew point has been

reduced by 6°C which is highly advantageous because the feed to the reactor may be

cooled by an additional 6°C without incurring the formation of a liquid phase.

Table 8

SI S2 S3 S4 S5 S6 S7 S8 S9 S10

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 60.0 77.2 60.0 60.0 60.0 59.8 60.0

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00 100.0

Mole Weight 41.93 36.46 36.46 41.93 41.93 41.93 36.46 41.93 41.93 2.02

Mass Flow (kg/h) 3900 0 0 3900 3900 3900 0 3900 3900 0

Mole Flow (kgmole/h) 930.0 0 0 930.0 930.0 930.0 0 930.0 930.0 0

Fraction

H drogen 0.714 0 0 0.714 0.723 0.723 0 0.723 0.723 1.000

Hydrogen chloride 0.009 1.000 1.000 0.009 0 0 1.000 0 0 0

Dichlorosilane 0.018 0 0 0.018 0.008 0.008 0 0.008 0.008 0 Trichlorosilane 0.165 0 0 0.165 0.175 0.175 0 0.175 0.175 0

Silicon tetrachloride 0.094 0 0 0.094 0.094 0.094 0 0.094 0.094 0

Table 9

SI S2 S3 S4 S5 S6 S7 S8 S9 S10

VapFrac 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Temp (°C) 60.0 60.0 60.0 59.8 74.9 60.0 60.0 60.0 59.9 60.0

Pressure (psig) 45.00 45.00 45.00 45.00 40.00 37.00 45.00 37.00 32.00 100.0

Mole Weight 41.93 36.46 36.46 34.91 34.91 34.91 36.46 34.91 34.91 2.02

Mass Flow (kg/h) 3900 0 0 3940 3940 3940 0 3940 3940 400.0

Mole Flow (kgmole/h) 930.0 0 0 1128. 1128. 1128. 0 1128. 1128. 198.4

Fraction

Hydrogen 0.714 0 0 0.764 0.772 0.772 0 0.772 0.772 1.000

Hydrogen chloride 0.009 1.000 1.000 0.008 0 0 1.000 0 0 0

Dichlorosilane 0.018 0 0 0.015 0.007 0.007 0 0.007 0.007 0

Trichlorosilane 0.165 0 0 0.136 0.144 0.144 0 0.144 0.144 0

Silicon tetrachloride 0.094 0 0 0.078 0.078 0.078 0 0.078 0.078 0

[0081] These tables show that, for a given CVD off -gas stream and for a given

first reactor feed temperature, when inert diluent is added to the reactant, for

example hydrogen gas, the first reactor effluent temperature is decreased from 77.2°C to 74.9°C and the dew point of the combined feed has been reduced by 6°C.

Accordingly, the addition of an inert diluent, e.g., hydrogen gas to a CVD off gas, prior to entry of the combined gases into a chlorination reactor as disclosed herein, is an

effective means of adjusting the operating temperature within the chlorination

reactor. In one aspect, the present disclosure provides a temperature control

mechanism wherein inert diluent, e.g., hydrogen makeup is added to a CVD off-gas to provide a feedstock, and the temperature of the feedstock is adjusted in concert with monitoring the temperature of the product gas exiting the chlorination reactor with or preferably without the formation of a condensed phase, where this temperature

control mechanism maintains the temperature within the reactor between minimum

and maximum pre-determined temperatures.

[0082] The following are additional embodiments of the present disclosure:

1) A chlorination process comprising: a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to nitrogen atoms;

b. providing reactants at a first temperature, the reactants comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride (HCI) to compounds containing Si (HChSi) and also characterized by a first molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si);

c. introducing the reactants to the first reactor; and

d. contacting the reactants with the reaction catalyst to generate heat and to provide first products which exit the first reactor, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing silicon (HChSi) which is lower than the first HChSi ratio, and also characterized by a second molar ratio of Si-CI bonds to compounds containing silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio.

The process of embodiment 1 wherein the solid support is an organic polymer. The process of embodiment 2 wherein the solid support is polystyrene that has been cross-linked with divinyl benzene.

The process of embodiment 1 wherein the nitrogen atoms are provided by a functional group selected from amino, alkylamino, and dialkylamino.

The process of embodiment 4 wherein the functional group is dimethylamino. The process of embodiment 1 wherein the reaction catalyst is a weak base anion exchange resin.

The process of embodiment 1 wherein the reaction catalyst undergoes conditioning prior to step c, the conditioning comprising dehydrating the reaction catalyst. ) The process of embodiment 7 wherein a) hot gas selected from hydrogen (H 2) and nitrogen ( N2) is passed through the reaction catalyst in order to dehydrate the reaction catalyst; or b) the conditioning comprises exposing the reaction catalyst to gaseous chlorosilane in the absence of hydrogen chloride.

) The process of embodiment 1 wherein the reactants that enter the reactor, and the products that exit the reactor, and the silicon compounds within the reactor, are all in the gas phase.

0) The process of embodiment 1 wherein the reactor operates at a reaction temperature, the reaction temperature being in the range of 25-100°C.

1) The process of embodiment 1 wherein the reactants come from a chemical vapor deposition reactor.

2) The process of embodiment 11 wherein hydrogen chloride is added to the reactants.

3) The process of embodiment 11 wherein hydrogen is added to the reactants.4) A chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to nitrogen atoms in the form of amino or dimethyl amino groups;

b. providing reactants at a first temperature, the reactants comprising hydrogen chloride and at least one compound having an X-H bond where X is an atom selected from the atoms of Group III, Group IV and Group V of the periodic table, the reactants characterized by a first molar ratio of hydrogen chloride (HCI) to compounds containing X (HCI:X) and also characterized by a first molar ratio of X-CI bonds to compounds containing X (X-CI:X);

c. introducing the reactants to the first reactor; and

d. contacting the reactants with the reaction catalyst to generate heat and provide first products upon exiting from the first reactor, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing X (HCI:X) which is lower than the first HCI:X ratio, and also characterized by a second molar ratio of X-CI bonds to compounds containing X (X-CI:X) which is greater than the first X-CI:X ratio.

) A system comprising a first reactor, the first reactor comprising:

a. a reaction catalyst, the reaction catalyst comprising a solid support and nitrogen atoms bonded to the solid support in the form of amino or dimethyl amino groups;

b. a first gas phase atmosphere in contact with the reaction catalyst, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane,

monochlorosilane, dichlorosilane and trichlorosilane, the first gas phase atmosphere characterized by a first molar ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first molar ratio of Si-CI bonds to silicon compounds (Si-CI :Si); and

c. a temperature within the first reactor, the temperature in excess of the dew point of the first gas phase atmosphere.

) The process of embodiment 1 further comprising cooling the reactants to a second temperature, the second temperature being lower than the first temperature, and introducing the reactants at the second temperature into the first reactor.

) The process of embodiment 16 wherein the temperature of the first products as they exit the first reactor (the third temperature) is monitored, and when the third temperature approaches a pre-determined maximum temperature, the temperature of the reactants to the first reactor is decreased so as to decrease the third temperature.

) The process of embodiment 1 further comprising

e. cooling the first products to a fifth temperature, the fifth temperature being lower than the third temperature;

f. providing a second reactor containing the reaction catalyst of the first reactor; g. introducing the first products into the second reactor; and

h. contacting the first products with the reaction catalyst to provide

second products upon exiting the second reactor and to generate heat, the second products characterized by a sixth temperature, a third molar ratio of hydrogen chloride to compounds containing the element silicon (HChSi) which is lower than the second HChSi ratio, and are also characterized by a third molar ratio of the number of Si-CI bonds to compounds containing the element silicon (Si-CI :Si) which is greater than the second Si-CI :Si ratio.

) The process of embodiment 1 wherein the reactor comprises internal cooling elements which are used to withdraw at least some of the heat from the reactor.

) The process of embodiment 1 wherein the reactor comprises more than one entrance port through which reactants may be introduced into the reactor; and introducing the reactants into both a first and a second entrance port of the reactor, reactants entering the first entrance port having a longer hold up time within the reactor than reactants which enter the second entrance port.

) The process of embodiment 1, wherein the composition of the reactants is altered prior to entry of the reactants into the reactor.

) The process of embodiment 21 wherein hydrogen chloride is added to the reactants.

) The process of embodiment 21 wherein hydrogen is added to the reactants to as to provide diluted reactants, and the diluted reactants are introduced into the reactor.

a. a reaction catalyst, the reaction catalyst comprising a solid support and nitrogen atoms bonded to the solid support in the form of amino or dimethyl amino groups; b. a second gas phase atmosphere in contact with the reaction catalyst, the second gas phase atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a second molar ratio of hydrogen chloride to compounds containing the element silicon (HChSi) which is lower than the first HChSi ratio and also characterized by a second molar ratio of the number of Si-CI bonds to compounds containing the element silicon (Si-CI :Si) which is greater than the first Si-CI :Si ratio; and c. a temperature within the second reactor, the temperature in excess of the boiling point of the second gas phase atmosphere.

25) The system of embodiment 24 wherein a cooling unit is positioned between the first and second reactors, the cooling unit cooling the product from the first reactor, before that product is utilized as a reactant in the second reactor.

[0083] Any of the various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference.

Claims

CLAIMS What is claimed is:

1. A chlorination process comprising:

a. providing a first reactor containing a reaction catalyst, the reaction catalyst comprising a solid support, the solid support bonded to nitrogen atoms;

c. introducing the reactants to the first reactor; and

2. The process of claim 1 wherein the solid support is an organic polymer.

3. The process of claim 2 wherein the solid support is polystyrene that has been cross-linked with divinyl benzene.

4. The process of claim 1 wherein the nitrogen atoms are provided by a functional group selected from amino, alkylamino, and dialkylamino.

5. The process of claim 4 wherein the functional group is dimethylamino.

6. The process of claim 1 wherein the reaction catalyst is a weak base anion exchange resin.

7. The process of claim 1 wherein the reaction catalyst undergoes conditioning prior to step c, the conditioning comprising dehydrating the reaction catalyst.

8. The process of claim 7 wherein a) hot gas selected from hydrogen (hh) and

nitrogen ( N2) is passed through the reaction catalyst in order to dehydrate the reaction catalyst; or b) the conditioning comprises exposing the reaction catalyst to gaseous chlorosilane in the absence of hydrogen chloride.

9. The process of claim 1 wherein the reactants that enter the reactor, and the

products that exit the reactor, and the silicon compounds within the reactor, are all in the gas phase.

10. The process of claim 1 wherein the reactor operates at a reaction temperature, the reaction temperature being in the range of 25-100°C.

11. The process of claim 1 wherein the reactants come from a chemical vapor

deposition reactor.

12. The process of claim 11 wherein hydrogen chloride is added to the reactants.

13. The process of claim 11 wherein hydrogen is added to the reactants.

14. A chlorination process comprising:

c. introducing the reactants to the first reactor; and

d. contacting the reactants with the reaction catalyst to generate heat and

provide first products upon exiting from the first reactor, the first products characterized by a second molar ratio of hydrogen chloride to compounds containing X (HCI:X) which is lower than the first HCI:X ratio, and also characterized by a second molar ratio of X-CI bonds to compounds containing X (X-CI:X) which is greater than the first X-CI:X ratio.

15. A system comprising a first reactor, the first reactor comprising: a reaction catalyst, the reaction catalyst comprising a solid support and nitrogen atoms bonded to the solid support in the form of amino or dimethyl amino groups;

a gas phase atmosphere in contact with the reaction catalyst, the atmosphere comprising hydrogen chloride and at least one silicon compound selected from the group consisting of silane, monochlorosilane, dichlorosilane and trichlorosilane, the reactants characterized by a first molar ratio of hydrogen chloride to silicon compounds (HChSi) and also characterized by a first molar ratio of Si-CI bonds to silicon compounds (Si-CI :Si); and

a temperature within the first reactor, the temperature in excess of the dew point of the atmosphere.