Apparatus and process for atomic or molecular layer deposition onto particles during pneumatic transport

Abstract

The invention provides a process for depositing a coating onto particles being pneumatically transported in a tube. The process comprising the steps of providing a tube having an inlet opening and an outlet opening; feeding a carrier gas entraining particles into the tube at or near the inlet opening of the tube to create a particle flow through the tube; and injecting a first self-terminating reactant into the tube via at least one injection point downstream from the inlet opening of the tube for reaction with the particles in the particle flow. The process is suitable for atomic layer deposition and molecular layer deposition. An apparatus for carrying out the process is also disclosed.

1 - 21 . (canceled) 
     
     
         22 . An apparatus comprising:
 (i) an elongated tube having a tube inlet opening and a tube outlet opening, wherein the tube has an inner diameter in the range of from 0.1 mm to 100 mm;   (ii) a fluidizer vessel comprising (i) a first inlet for feeding particles into the fluidizer vessel, (ii) a second inlet for feeding a carrier gas into the fluidizer vessel to fluidize the particles and (iii) an outlet fluidly connected to the tube inlet opening and configured for feeding the carrier gas entraining the particles into the tube, thereby pneumatically transporting the particles in the tube;   (iii) a plurality of temperature control units; and   (iv) a separation device fluidly connected to the tube outlet opening and having a gas outlet and particle outlet;   wherein the tube comprises a plurality of injection points downstream from the tube inlet opening for introducing two or more different reactants via different injections points of the plurality of injections points into the tube, for atomic or molecular layer deposition on the particles, wherein the plurality of injection points are numbered sequentially from the tube inlet opening and are spaced apart along at least a portion of a length of the tube;   wherein first tube segments are arranged downstream from odd-numbered injection points and upstream to even-numbered injection points and wherein second tube segments are arranged downstream from even-numbered injection points to odd-numbered injection points; and   wherein the tube at the first tube segments is surrounded with a first portion of the plurality of temperature control units and wherein the tube at the second tube segments is surrounded with a second portion of the plurality of temperature control units, wherein the temperature control units of the first portion of the plurality of temperature control units are configured for maintaining the first tube segments at a first temperature and wherein the temperature control units of the second portion of the plurality of temperature control units are configured for maintaining the second tube segments at a second temperature.   
     
     
         23 . The apparatus of  claim 22 , wherein subsequent injection points are arranged at least 10 mm apart from each other. 
     
     
         24 . The apparatus of  claim 22 , wherein the tube inner diameter is constant over the length of the tube. 
     
     
         25 . The apparatus of  claim 22 , wherein the separation device comprises s a cyclone. 
     
     
         26 . The apparatus of  claim 22 , wherein the odd-numbered injection points are arranged for injection of a first reactant and wherein the second injection points are arranged for injection of a second reactant. 
     
     
         27 . The apparatus of  claim 26 , wherein at least one of the temperature control units of the plurality of temperature control units is disposed around the tube at a location upstream of the plurality of injection points and for heating the particles flowing in the tube to a temperature corresponding to a reaction temperature required for the first reactant to react with the particles. 
     
     
         28 . The apparatus of  claim 22 , configured for providing the carrier gas and the particles flowing in the same direction during operation. 
     
     
         29 . The apparatus of  claim 22 , further comprising one or more flush points along at least part of the length of the tube for removing reaction by-products from the tube, wherein the apparatus is configured for increasing a linear velocity along the tube of gas pneumatically transporting the particles by controlling (i) an amount of the two or more different reactants introduced into the tube via the different injections points of the plurality of injections points and (ii) an amount of reaction by-products removed from the tube at the one or more flush points. 
     
     
         30 . The apparatus of  claim 29 , further comprising a control system configured for controlling:
 the linear velocity along the tube of the gas pneumatically transporting the particles by controlling (i) the amount of the two or more different reactants introduced via the different injections points into the tube and (ii) the amount of reaction by-products removed from the tube at the one or more flush points, and   the first temperature and the second temperature by controlling the plurality of temperature control units.   
     
     
         31 . The apparatus of  claim 30 , wherein the control system is configured for controlling the linear velocity of the gas in the range of 0.02 to 30 m/s. 
     
     
         32 . The apparatus of  claim 26 , wherein one or more flush points comprise a filter to allow reaction products to be removed while keeping the particles in the tube. 
     
     
         33 . The apparatus of  claim 22 , wherein the tube has an internal diameter in the range of from 1 mm to 20 mm. 
     
     
         34 . The apparatus of  claim 22 , wherein the tube has a length of from 0.1 m to 500 m, and wherein the tube is folded or coiled. 
     
     
         35 . The apparatus of  claim 22 , wherein the tube is contained in a chamber provided with heat exchangers, wherein the chamber can be kept at a temperature in the range of from 0° C. to 1000° C. 
     
     
         36 . The apparatus of  claim 22 , wherein the first tube segments are made of a different material than the second tube segments. 
     
     
         37 . The apparatus of  claim 36 , wherein the first segments are made of stainless steel and the second tube segments are made of Teflon or wherein the second tube segments are made of stainless steel and the first tube segments are made of Teflon. 
     
     
         38 . A process for depositing a coating onto particles being pneumatically transported in a tube, said process comprising the steps of:
 (i) providing the apparatus of  claim 22 ;   (ii) feeding particles and a carrier gas into the fluidizer vessel;   (iii) fluidizing the particles in the fluidizer vessel and feeding the carrier gas entraining particles into the tube to create a particle flow through the tube;   (iv) introducing two or more different reactants via different injections points of the plurality of injections points into the tube, for atomic or molecular layer deposition on the particles; and   (v) maintaining the first tube segments at a first temperature and maintaining the second tube segments at a second temperature.   
     
     
         39 . The process of  claim 38 , wherein a first reactant is injected into the tube via the odd-numbered injection points and a second reactant is injected into the tube via the even-numbered injection points. 
     
     
         40 . The process of  claim 39 , wherein the second reactant is a second self-terminating reactant and wherein the first reactant is a precursor for the second reactant. 
     
     
         41 . The process of  claim 38 , wherein a linear velocity of the carrier gas is selected to cause entrainment of the particles through the tube.