Method for platinum group metals recovery from spent catalysts

Abstract

A method for recovery of platinum group metals from a spent catalyst is described. The method includes crushing the spent catalyst to obtain a catalyst particulate material including particles having a predetermined grain size. The method includes subjecting the catalyst particulate material in the reaction zone at a predetermined temperature for a predetermined time period in contact with solid chlorine-containing material and solid silicon-containing material to obtain volatile platinum group metal-containing chloride product, and cooling to convert the product into solid phase platinum group metal-containing materials.

Claims

1. A method for recovery of platinum group metals from a spent catalyst, the method comprising: obtaining a catalyst particulate material comprising platinum group metals from said spent catalyst wherein said particulate material has a predetermined grain size; mixing said catalyst particulate material with a solid chlorine-containing material and a solid silicon-containing material in a reaction zone; subjecting said mixture in said reaction zone to a predetermined temperature for a predetermined time period; thereby reacting said platinum group metals with said solid chlorine-containing material and said solid silicon-containing material; and provide a volatile platinum group metal-containing chloride product in said reaction zone; treating said reaction zone with air, O.sub.2 or combination thereof; cooling said volatile platinum group metal-containing chloride product in a cooling zone to convert said volatile platinum group metal-containing chloride product into a solid phase platinum group metal-containing materials.

2. The method of claim 1, wherein said solid chlorine-containing material comprises at least one chloride salt.

3. The method of claim 2, wherein said chloride salt is selected from the group consisting of: alkali metal chlorides, alkaline earth metals chlorides, aluminum chloride, ammonium chloride and any combination thereof.

4. The method of claim 1, wherein said solid silicon-containing material comprises at least one silica-containing material.

5. The method of claim 4, wherein said silica-containing material is selected from the group consisting of: pure silica, silica-containing sand, silica-containing waste and any combination thereof.

6. The method of claim 1, wherein said silica-containing material has a predetermined grain size in the range of 5 microns to 5 mm.

7. The method of claim 1, wherein a surface area of said silicon-containing material is in the range of 50 m.sup.2/gr to 400 m.sup.2/gr.

8. The method of claim 1, wherein said predetermined grain size of said catalyst particulate material is in the range of 30 microns to 200 mm.

9. The method of claim 1, wherein said solid chlorine-containing material is in the range of 50 gram to 2 kilogram per each kilogram of the spent catalyst.

10. The method of claim 1, wherein said solid silicon-containing material is in the range of 50 gram to 2 kilogram per each kilogram of the spent catalyst.

11. The method of claim 1, wherein oxygen content in said oxygen, air or combination thereof is in the range of 0.1 weight percent to 98 weight percent.

12. The method of claim 1, wherein said predetermined temperature in the reaction zone is in the range of 300 degrees Celsius to 1200 degrees Celsius.

13. The method of claim 1, wherein said predetermined time period for heating said mixture is in the range of 10 min to 300 min.

14. The method of claim 1, wherein the step of obtaining of a catalyst particulate material comprising platinum group metals comprises crushing said spent catalyst to obtain a catalyst particulate material.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

(2) FIG. 1: XRD patterns of the calcium silicate after sintering of the catalyst particulate material with calcium chloride and silica addition.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(3) In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

(4) In one embodiment, this invention provides a method for recovery of platinum group metals from a spent catalyst, the method comprising:

(5) obtaining a catalyst particulate material comprising platinum group metals from said spent catalyst wherein said particulate material has a predetermined grain size;

(6) mixing said catalyst particulate material with a solid chlorine-containing material and a solid silicon-containing material in a reaction zone;

(7) subjecting said mixture in said reaction zone to a predetermined temperature for a predetermined time period; thereby reacting said platinum group metals with said solid chlorine-containing material and solid silicon-containing material; and provide a volatile platinum group metal-containing chloride product in said reaction zone;

(8) treating said reaction zone with oxygen-containing gas;

(9) cooling said volatile platinum group metal-containing chloride product in a cooling zone to convert said volatile platinum group metal-containing chloride product into solid phase platinum group metal-containing materials.

(10) In the present description and claims, the expression “platinum group metals” is broadly used, whether alone or in combination, for all of the elements of the platinum group, namely the elements rhodium, palladium, iridium, platinum, ruthenium and osmium. Each represents a separate embodiment of this invention.

(11) The spent catalysts, which contain the platinum group metals to be recovered, may be in various forms, namely, for example, in the form of pellets or in the form of monoliths. It will be appreciated that such catalysts are widely described in the art, both with respect to their structure and their composition.

(12) The spent catalysts generally may contain various impurities, such as zirconia, silica, ceria, alumina, carbonaceous substances and the like. However, the method of the invention are insensitive to the presence of these impurities.

(13) In one embodiment, the method of this invention comprises obtaining a catalyst particulate material comprising platinum group metals from said spent catalyst wherein said particulate material has a predetermined grain size. In another embodiment, the catalyst particulate material is obtained by crushing the spent catalyst. The term “crushing” refers to grinding or miling. This stage is required when a spent catalyst is in the form of a monolith. During the crushing, the catalyst is grinded, and thus converted into a particulate material whose mean particle size may range, for example from 30 microns to 200 mm. In another embodiment, the particulate material has mean particle size between 30 microns to 1 millimeters. In another embodiment, the particulate material has mean particle size between 100 microns to 1 millimeter. In another embodiment, the particulate material has mean particle size between 30 microns to 100 millimeter. In another embodiment, the particulate material has mean particle size between 30 microns to 100 millimeters. In another embodiment, the particulate material has mean particle size between 100 millimeters to 200 millimeters.

(14) According to an embodiment of the present invention, the method includes mixing the catalyst particulate material with a solid chlorine-containing material with said solid chlorine-containing material and solid silicon-containing material in a reaction zone. In another embodiment, the solid chlorine-containing material comprises at least one chloride salt. In another ambodiment, the chloride salt is selected from the group consisting of: alkali metal chlorides, hypochlorite salts, alkaline earth metal chlorides, aluminum chloride, ammonium chloride and any combination thereof. In another embodiment, the solid chlorine-containing material is selected from alkali metal chloride, hypochlorite salt, alkaline earth metal chlorides, aluminum chloride and ammonium chloride. In another embodiment, the solid chlorine-containing material is an alkali metal chloride. In another embodiment, the solid chlorine-containing material is alkaline earth metals chloride. In another embodiment, the solid chlorine-containing material is aluminum chloride. In another embodiment, the solid chlorine-containing material is ammonium chloride. Examples of alkali metal chlorides include, but are not limited to, potassium chloride and sodium chloride. Examples of alkaline earth metal chlorides include, but are not limited to, calcium chloride, magnesium chloride and barium chloride.

(15) In another embodiment, the solid chlorine-containing material is in the range of 50 gram to 2 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid chlorine-containing material is in the range of 100 gram to 500 gram per each kilogram of the spent catalyst. In another embodiment, the solid chlorine-containing material is in the range of 50 gram to 1 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid chlorine-containing material is in the range of 100 gram to 1 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid chlorine-containing material is in the range of 500 gram to 2 kilogram per each kilogram of the spent catalyst.

(16) In another embodiment, the solid silicon-containing material comprises at least one silica-containing material. In another embodiment, the silica-containing material is selected from the group consisting of: pure silica, silica-containing sand, silica-containing waste and any combination thereof. Each represents a separate embodiment of this invention. In another embodiment, the silica-containing material is pure silica. In another embodiment, the silica-containing material is silica-containing sand. In another embodiment, the silica-containing material is silica-containing waste.

(17) In another embodiment, the solid silicon-containing material is in the range of 50 gram to 2 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid silicon-containing material is in the range of 100 gram to 500 gram per each kilogram of the spent catalyst. In another embodiment, the solid silicon-containing material is in the range of 50 gram to 1 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid silicon-containing material is in the range of 100 gram to 1 kilogram per each kilogram of the spent catalyst. In another embodiment, the solid silicon-containing material is in the range of 500 gram to 2 kilogram per each kilogram of the spent catalyst.

(18) According to an embodiment of the present invention, the method includes mixing the catalyst particulate material with a solid chlorine-containing material and a solid silicon-containing material, wherein the solid silicon-containing material has a predetermined grain size in the range of 5 microns to 5 mm. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 5 microns to 100 microns. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between microns to 500 microns. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 100 microns to 1 millimeters. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 5 microns to 1 millimeters. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 100 microns to 2 millimeters. In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 100 microns to 3 millimeters.

(19) In another embodiment, the grain size of the solid silicon-containing material has mean grain size between 100 microns to 4 millimeters. In another embodiment, the surface area of said silicon-containing material is in the range of 50 m.sup.2/gr to 400 m.sup.2/gr. In another embodiment, the surface area of said silicon-containing material is in the range of 50 m.sup.2/gr to 100 m.sup.2/gr. In another embodiment, the surface area of said silicon-containing material is in the range of 50 m.sup.2/gr to 200 m.sup.2/gr. In another embodiment, the surface area of said silicon-containing material is in the range of 50 m.sup.2/gr to 300 m.sup.2/gr.

(20) According to an embodiment of the present invention, the method includes subjecting the mixture of the catalyst particulate material, the solid chlorine-containing material and the solid silicon-containing material in a reaction zone and subjecting the mixture in said reaction zone to a predetermined temperature for a predetermined time period; thereby reacting said platinum group metals with said solid chlorine-containing material and solid silicon-containing material; and provide a volatile platinum group metal-containing chloride product in said reaction zone. In another embodiment, the predetermined temperature refers to heating the mixture of the catalyst particulate material, the solid chlorine-containing material and the solid silicon-containing material. In another embodiment, the mixture is heated to a temperature between 300 degrees Celsius and 1200 degrees Celsius. In another embodiment, the mixture is heated to a temperature between 300 degrees Celsius and 1000 degrees Celsius. In another embodiment, the mixture is heated to a temperature between 500 degrees Celsius and 1000 degrees Celsius. In another embodiment, the mixture is heated for a period converting the solid to volatile. In another embodiment, the mixture is heated for between 10 minutes to 300 minutes. In another embodiment, the mixture is heated for between 10 minutes to 100 minutes. In another embodiment, the mixture is heated for between 60 minutes to 180 minutes. In another embodiment, the mixture is heated for between 90 minutes to 300 minutes.

(21) In another embodiment, an example of the method of this invention is presented by the following equation for recovery of platinum using CaCl.sub.2:
Total reaction:
Pt+CaCl.sub.2+SiO.sub.2+0.5O.sub.2=PtCl.sub.2+CaOSiO.sub.2

(22) The chloride salt melts on the surface (CaCl.sub.2 melts at 782° C.), decomposes in the presence of oxygen and dissolves the solids (silica, platinum group metals and oxide salt). All reactions take place in the liquid phase on the surface with oxygen gas addition. Particles size and specific surface area of silica have influence on the process, as it determines the dissolution of the silica in the liquid chloride salt phase and the formation of the silicate salt.

(23) The silica accelerates the decomposition reaction of the chloride salt in the presence of air. Silica binds the oxide salt to yield a silicate salt.

(24) According to an embodiment of the present invention, the method includes treating said reaction zone with oxygen-containing gas. In another embodiment, the oxygen-containing gas comprises air or O.sub.2. In another embodiment, the oxygen content in said oxygen-containing gas is in the range of 0.1 weight percent to 98 weight percent.

(25) In one embodiment, this invention provides an apparatus for recovery of platinum group metals from a spent catalyst comprising:

(26) a reaction zone with one or more inlet ports to a catalyst particulate material, a solid silicon-containing material and a solid-chlorine containing material;

(27) a heater;

(28) platinum group metal-containing vapor outlet port and one or more corresponding cooling manifolds through which a platinum group metal-containing vapor is released from the reaction zone;

(29) wherein

(30) a catalyst particulate material, a solid silicon-containing material and a solid-chlorine containing material are fed into the reaction zone and the reaction mixture is heated at a predetermined temperature by the heater, providing a chemical reaction between platinum group metals, the solid-chlorine containing material and the silica to yield a volatile platinum group metal-containing chloride product.

(31) Platinum group metal can be recovered from the platinum group metal-containing materials in the solid phase by any recovery means conventional in the art. For example, this may conveniently be achieved by dissolving the platinum group metal-containing condensed solid products in water and treating the solution with metallic zinc to reduce the platinum group metal.

(32) The following examples are given by way of illustration, and therefore should not be construed to limit, in any manner, the scope of the present invention.

EXAMPLES

Example 1

(33) Method A:

(34) A catalyst with 0.45% platinum was crushed and mixed with calcium chloride and silica (Mixture composition is presented in the Table 1). Thereafter mixture was treated with air at 1050° C. All of parameters and results are presented in the Table 1.

(35) The best results were obtained after mixing with calcium chloride and silica (Samples 1-3).

(36) TABLE-US-00001 TABLE 1 Platinum extraction. Catalyst CaCl.sub.2 quantity SiO.sub.2 quantity Platinum Sample quantity gr/kg of gr/kg of extraction number gr gr catalyst gr catalyst % 1 100 70 700 120 1200 94 2 100 120 1200 70 700 91 3 100 50 500 150 1500 93 4 100 40 400 10 100 75 5 100 70 700 0 0 56 6 100 65 650 0 0 62 7 100 15 150 2 20 41 8 100 40 400 3 30 52
Method B:

(37) A catalyst with 0.25% palladium was crushed and mixed with calcium chloride and silica (Mixture composition is presented in the Table 2). Thereafter mixture was treated with air at 1050° C. All of parameters and results are presented in the Table 2.

(38) The best results were received after mixing with calcium chloride and silica (Samples 1-3).

(39) TABLE-US-00002 TABLE 2 Palladium extraction. Catalyst CaCl.sub.2 quantity SiO.sub.2 quantity Palladium Sample quantity gr/kg of gr/kg of extraction number gr gr catalyst gr catalyst % 1 100 60 600 120 1200 93 2 100 120 1200 60 600 92 3 100 150 1500 150 1500 93 4 100 52 520 0 0 54 5 100 120 1200 0 0 52 6 100 15 150 2 20 15 7 100 40 400 3 30 23

Example 2

(40) The method of this invention for recovery of platinum group metals from a spent catalyst as described in Example 1 is summarized in the following equation:
Pt+CaCl.sub.2+SiO.sub.2+0.5O.sub.2=PtCl.sub.2+CaSiO.sub.3.

(41) FIG. 1 provides XRD of the calcium silicate. The main product is a meta-calcium silicate CaSiO.sub.3.

(42) Silica accelerates the formation of PtCl.sub.2 by the formation of the calcium silicate which is thermodynamic stable product (Table 3).

(43) Results of thermodynamic calculations are provided in Table 3, comparing the Gibbs energy of a reaction including silica and without silica as one of the reagents of the reaction.

(44) TABLE-US-00003 TABLE 3 Results of the thermodynamic calculations. Gibbs Energy (kJ/mole) Reaction 400° C. 500° C. 600° C. 700° C. 800° C. 900° C. 1000° C. 1100° C. 2Pd + 2CaCl.sub.2 + O.sub.2 = 2PdCl.sub.2 gas + 2CaO 11 3 −4 −12 −19 −27 −34 42 2Pd + 2CaCl.sub.2 + 2SiO.sub.2 + O.sub.2 = 2PdCl.sub.2 gas + 2 CaSiO.sub.3 −171 −176 −185 −192 −199 −206 −213 −220

(45) It is important, therefore, that the scope of the invention is not construed as being limited by the illustrative embodiments set forth herein. Other variations are possible within the scope of the present invention as defined in the appended claims. Other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to different combinations or directed to the same combinations, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the present description.