Process for producing silicon-containing materials in a stirred-tank reactor
A process for producing silicon-containing materials. Where the silicon-containing materials are produced by thermal decomposition of silicon precursors in the presence of porous particles and silicon is deposited within pores and on a surface of the porous particles. The thermal decomposition of the silicon precursors takes place in the reaction zone of a gas-traversed reactor and the particles are circulated in the reaction zone during the thermal decomposition by using a stirrer which is close-clearance in the heated regions and the stirring mechanism is in close-clearance in accordance with equation 1 W ( h ) = u R ( h ) u B ( h ) . ( 1 )
1 . A process for producing silicon-containing materials, comprising:
thermal decomposition of silicon precursors in the presence of porous particles, wherein silicon is deposited in pores and on a surface of the porous particles;
wherein the thermal decomposition of the silicon precursors takes place in a reaction zone of a gas-traversed reactor and the porous particles are circulated in the reaction zone during the thermal decomposition by using a stirring mechanism which is close-clearance in heated regions of the reaction zone;
wherein the reaction zone is the region in the reactor in which a stirred particle bed is contacted with the silicon precursors and the precursor is decomposed;
wherein the stirring mechanism is in close-clearance in accordance with equation 1
W
(
h
)
=
u
R
(
h
)
u
B
(
h
)
(
1
)
wherein for half of all values of h the close clearance W(h) in the reaction zone is W(h 50% ) >0.95; and
wherein u R (h)=the outer circumference of the stirring mechanism in the sectional face at the height coordinate h and u B (h)=the inner circumference of the reactor in the sectional face at the height coordinate h.
2 . The process of claim 1 , wherein the reaction zone of the reactor is rotationally symmetrical;
wherein the stirring mechanism is close-clearance if in equation 1
W
(
h
)
=
u
R
(
h
)
u
B
(
h
)
(
1
)
wherein W(h)=the close clearance of a stirring mechanism in a rotationally symmetrical reactor, defined as the quotient of the circumferences of two planar sectional faces perpendicular to the rotational axis of two rotational faces;
wherein h represents the height coordinate;
wherein u R (h)=the circumference of a circular inner sectional face calculated according to equation 2
u
R
(
h
)
=
2
π
r
R
(
h
)
(
2
)
wherein at multiple arbitrary points h of the rotational face perpendicular to the rotational axis through a planar section;
wherein r R (h)=the distance from the rotational axis to the the circular inner sectional face;
wherein the stirring mechanism includes all components attached thereto;
wherein u B (h)=the circumference of a circular outer rotational face calculated according to equation 3
u
B
(
h
)
=
2
π
r
B
(
h
)
(
3
)
wherein at each arbitrary point h of the rotational face perpendicular to the rotational axis through a planar section, said rotational face being formed by rotation of the circular outer rotational face of the reactor about the rotational axis;
wherein r B (h)=the distance of the circular outer rotational face of the reactor to the rotational axis; and
wherein for half of all values of h the close clearance W(h) in the reaction zone must be W(h 50% ) >0.95.
3 . The process of claim 1 , wherein over the course of the deposition of the silicon precursor a metered addition takes place at a rate of 0.1-2 g of Si per cm 3 of pore volume of the porous particles used per hour.
4 . The process of claim 1 , wherein over the course of the deposition the silicon precursor is metered in at a rate of 1-700 kg of Si per m 2 of a largest flow cross-sectional area of the reactor in the reaction zone per hour, and wherein the cross-sectional area is measured for the empty reactor.
5 . The process of claim 1 , wherein the thermal decomposition of the silicon precursors takes place at 0.08 to 5 MPa.
6 . The process of claim 1 , wherein the thermal decomposition of the silicon precursors is carried out at 280 to 900° C.
7 . The process of claim 1 , wherein the stirred particle bed has a bed temperature in the reaction zone of the reactor equipped with the stirring mechanism is in the range from 100 to 1000° C.
8 . The process of claim 1 , wherein the process is carried out in a cascade reactor system comprising multiple reactors.
9 . The process of claim 1 , wherein the process comprises at least Phases 1 to 3;
wherein the Phase 1 comprises filling of a reactor A with the porous particles and pretreatment of the porous particles with subsequent transfer of at least a portion of the pretreated porous particles to a reactor B;
wherein the Phase 2 comprises passing of a flow of a gas consisting of an inert gas and/or at least one reactive component containing a silicon precursor and/or at least one silicon-free precursor through reactor B;
conditioning of the reactor to a temperature at which the thermal decomposition of the reactive component takes place on the surface and in the pores of the porous particles;
wherein the particle bed in reactor B is circulated with a stirring mechanism such that the movement state of the particle bed can be described with Froude numbers in the range between 1 and 10
wherein the gas phase is supplied to reactor B while the particle bed in reactor B is circulated by the stirring mechanism such that the ratio of circulating time to mean residence time of the reactive component is less than 1;
wherein after the silicon has been introduced into and onto the pores of the porous particles at least a portion of the silicon-containing materials are transferred to reactor C; and
wherein the Phase 3 comprises aftertreatment of the silicon-containing particles for functionalization and/or coating of the surface of the silicon-containing particles, and cooling of the particles to a defined temperature and withdrawal of silicon-containing materials from reactor C.