CA2740074C - Polymer bound solid metal complex catalyst for hydrogen reforming from formic acid - Google Patents
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Abstract
A polymer bound heterogeneous metal complex catalyst which is capable of reforming hydrogen from formic acid is discussed. This noble metal complex is permanently bound to a polymer surface from a ligand which is associated with this catalyst. In a preferred case the noble metal is ruthenium, the ligands are polymer bound Triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt (TPPTS) and the polymer backbone is polystyrene. In a preferred embodiment, two ligands of TPPTS are connected to the central metal atom. Both ligand molecules, or at least one of them, are chemically bonded to the polymer backbone from the para-position of the one phenyl group in the TPPTS.
Because of this attachment the system becomes a water insoluble solid. Due to the association of meta-sulfonated phenyl groups in TPPTS ligands resulting in the ruthenium complex being hydrophilic for efficient surface reaction. The polymer bound ruthenium complex catalyst is ideal to reform formic acid to hydrogen at low temperature. Because of the permanent bonding of this catalyst to the polystyrene backbone leaching out of the catalyst from the reformer does not occur, and can be used in different forms such as fine powder, particles, sheets, rods, flakes, beads, tubes, blocks, etc. The catalyst is hydrophilic but insoluble in water, formic acid and other solvents. The catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the catalyst is ideal for orientation independent reformers.
Because of this attachment the system becomes a water insoluble solid. Due to the association of meta-sulfonated phenyl groups in TPPTS ligands resulting in the ruthenium complex being hydrophilic for efficient surface reaction. The polymer bound ruthenium complex catalyst is ideal to reform formic acid to hydrogen at low temperature. Because of the permanent bonding of this catalyst to the polystyrene backbone leaching out of the catalyst from the reformer does not occur, and can be used in different forms such as fine powder, particles, sheets, rods, flakes, beads, tubes, blocks, etc. The catalyst is hydrophilic but insoluble in water, formic acid and other solvents. The catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the catalyst is ideal for orientation independent reformers.
Description
Polymer bound solid metal complex catalyst for hydrogen reforming from formic acid Field of the Invention The invention relates to materials used in the catalytic production of hydrogen via hydrocarbon reforming. In particular, this invention relates to a heterogeneous polymer bound solid metal complex catalyst, in which noble metal complex is chemically bound to organic-polymer via the ligands associated with catalyst molecules. The invention is best suited for multiple cycle portable reformers.
Background of the Invention Hydrogen gas, Hz, is a versatile energy carrier that can be used in energy conversion devices such as fuel cells and combustion engines. The primary challenges in the widespread adoption of H2 as an energy carrier lie in the low volumetric energy density of a gaseous fuel, especially in portable applications where high power density is required. The ideal solution is to utilize an energy dense liquid hydrocarbon fuel, and generate hydrogen on-demand in a fuel processor via chemical reforming. Small chain alcohol and carboxylic acids have been widely exploited for this purpose, though formic acid in particular has many desirable properties, being liquid at nominal temperature and pressure, non-toxic, inflammable,, and derivable in a carbon-neutral process. One major drawback with traditional hydrocarbon reforming, however, is the high temperature (i.e. >
C) environment potentially required in attaining significant hydrogen production rates, which is problematic for safety and also inefficient, consuming a significant portion of the energy produced. Catalysts for high temperature reforming are conventionally supported or stored in a solid phase in solid support such as Zeolite or Carbon, as the catalyst coating methods and processing (sintering) typically may require high temperatures unsuitable for polymers.
In addressing the limitations of high temperature reforming (> 200 C), a number of recent publications have dealt with low temperature (i.e. < 150 C) reforming of formic acid utilizing a class of ruthenium complexes in aqueous solution. These homogeneous catalysts have several advantages for use in fuel cell applications in particular, such as very high selectivity to H2. with ppm levels of carbon monoxide (CO); rapid start-up time due to low temperature operation;
and the ability to use a wide range of formic acid concentrations (15 ¨ 98%
w/w) as feedstock.
For reformed H2 use in hydrogen fuel cells, it is important to have a hydrogen gas production process producing high purity hydrogen on demand at acceptable pressures, as carbon monoxide is poisonous to the catalyst in most fuel cells. For the case of formic acid decomposition has two paths, dehydrogenation producing H2 and 002, or dehydration producing CO and H20, as shown in the equations A and B.
HCOOH ---> H2 + CO2 Eq.A Dehydrogenation HCOOH --> CO + H20 Eq.B Dehydration Effective reforming of formic acid for fuel cells, then benefits from highly selective dehydrogenation for increased H2 yield and very low levels of CO
poisonous to most PEM cells.
New developments in liquid phase catalysis have demonstrated the desired selective dehydrogenation. A novel process for high selectivity and low temperature formic acid decomposition has been recently published and patent pending (US publication No: U52010/0068131) using a ruthenium based metal complex catalyst in aqueous phase. This novel process achieves rapid low temperature decomposition at rates up to 50X faster by the addition of sodium formate to > 95% conversion within 4 hours. Further recycling the catalyst led to 200X faster conversion within 1 hour.
This aqueous catalyst formulation ('8131 patent) has many advantages for reforming formic acid through selective dehydrogenation efficiently to produce high pressure hydrogen product for use in portable fuel cells with acceptable trace amounts of CO poison, specifically active long life and producing a positive pressure of hydrogen and primarily all gas product, as reviewed in the references.
Realizing the benefits of such catalyst formulations and reactions has many major challenges. These are addressed with respect to reforming formic acid.
For example, use of liquid state ruthenium based metal complex catalyst for hydrogen reforming process from formic acid is a major drawback for the
Background of the Invention Hydrogen gas, Hz, is a versatile energy carrier that can be used in energy conversion devices such as fuel cells and combustion engines. The primary challenges in the widespread adoption of H2 as an energy carrier lie in the low volumetric energy density of a gaseous fuel, especially in portable applications where high power density is required. The ideal solution is to utilize an energy dense liquid hydrocarbon fuel, and generate hydrogen on-demand in a fuel processor via chemical reforming. Small chain alcohol and carboxylic acids have been widely exploited for this purpose, though formic acid in particular has many desirable properties, being liquid at nominal temperature and pressure, non-toxic, inflammable,, and derivable in a carbon-neutral process. One major drawback with traditional hydrocarbon reforming, however, is the high temperature (i.e. >
C) environment potentially required in attaining significant hydrogen production rates, which is problematic for safety and also inefficient, consuming a significant portion of the energy produced. Catalysts for high temperature reforming are conventionally supported or stored in a solid phase in solid support such as Zeolite or Carbon, as the catalyst coating methods and processing (sintering) typically may require high temperatures unsuitable for polymers.
In addressing the limitations of high temperature reforming (> 200 C), a number of recent publications have dealt with low temperature (i.e. < 150 C) reforming of formic acid utilizing a class of ruthenium complexes in aqueous solution. These homogeneous catalysts have several advantages for use in fuel cell applications in particular, such as very high selectivity to H2. with ppm levels of carbon monoxide (CO); rapid start-up time due to low temperature operation;
and the ability to use a wide range of formic acid concentrations (15 ¨ 98%
w/w) as feedstock.
For reformed H2 use in hydrogen fuel cells, it is important to have a hydrogen gas production process producing high purity hydrogen on demand at acceptable pressures, as carbon monoxide is poisonous to the catalyst in most fuel cells. For the case of formic acid decomposition has two paths, dehydrogenation producing H2 and 002, or dehydration producing CO and H20, as shown in the equations A and B.
HCOOH ---> H2 + CO2 Eq.A Dehydrogenation HCOOH --> CO + H20 Eq.B Dehydration Effective reforming of formic acid for fuel cells, then benefits from highly selective dehydrogenation for increased H2 yield and very low levels of CO
poisonous to most PEM cells.
New developments in liquid phase catalysis have demonstrated the desired selective dehydrogenation. A novel process for high selectivity and low temperature formic acid decomposition has been recently published and patent pending (US publication No: U52010/0068131) using a ruthenium based metal complex catalyst in aqueous phase. This novel process achieves rapid low temperature decomposition at rates up to 50X faster by the addition of sodium formate to > 95% conversion within 4 hours. Further recycling the catalyst led to 200X faster conversion within 1 hour.
This aqueous catalyst formulation ('8131 patent) has many advantages for reforming formic acid through selective dehydrogenation efficiently to produce high pressure hydrogen product for use in portable fuel cells with acceptable trace amounts of CO poison, specifically active long life and producing a positive pressure of hydrogen and primarily all gas product, as reviewed in the references.
Realizing the benefits of such catalyst formulations and reactions has many major challenges. These are addressed with respect to reforming formic acid.
For example, use of liquid state ruthenium based metal complex catalyst for hydrogen reforming process from formic acid is a major drawback for the
2 development of orientation independent reforming. A system using aqueous formic acid would be typically operated at high temperatures (-100 C). Because of the high temperature and continuous gas production (H2 and CO2) this system may tend to be over flooded with hot liquid including unreacted formic acid.
This exhaust liquid may be harmful for the user and also damage the hydrogen fuel cell. Therefore, a reformer that operates orientation independent is hard to achieve with a liquid based catalyst to use in portable device. There is a need for a high selectivity catalyst for use in an orientation independent reformer.
Catalyst leaching out of catalyst from a reformer is another major problem when using typical water soluble ruthenium based metal complex catalyst for reforming hydrogen from formic acid. Leached solution may contain both formic acid and toxic ruthenium compound that are harmful to the environment. In addition, they may damage and poison the hydrogen fuel cell. There is a need for a high selectivity catalyst that limits or avoids toxic leaching.
Extended operation may be limited due to the concentration of the catalyst in the reformer declining gradually, from gradual overflowing of the system with active catalyst and gradual leaching out of catalyst with exhaust gas, water and formic acid vapors. This will result a gradual decreasing of hydrogen production rate and eventually potential insufficient formation of hydrogen to obtain a maximum output from an attached fuel cell. There is a need for a high selectivity solid catalyst that extends the effective operating time of the catalyst.
Typical liquid based ruthenium metal complex catalyst is challenging to be reconditioned (reactivate, purified) and recycled after contaminated with foreign impurities (coming from formic acid and other construction materials). Impure catalyst may decompose gradually and be inactive eventually. When this occurs, the inactive catalyst mixture has to be discarded and the reformer has to be refilled with brand new catalyst mixture or whole reformer has to be discarded.
There is a need for a high selectivity solid catalyst that is convenient for recycling and safe in disposal.
Immobilization of liquid based ruthenium metal complex catalyst may be considered, however may result in less reactivity due to several reasons.
(a) Low heat transfer throughout the system.
This exhaust liquid may be harmful for the user and also damage the hydrogen fuel cell. Therefore, a reformer that operates orientation independent is hard to achieve with a liquid based catalyst to use in portable device. There is a need for a high selectivity catalyst for use in an orientation independent reformer.
Catalyst leaching out of catalyst from a reformer is another major problem when using typical water soluble ruthenium based metal complex catalyst for reforming hydrogen from formic acid. Leached solution may contain both formic acid and toxic ruthenium compound that are harmful to the environment. In addition, they may damage and poison the hydrogen fuel cell. There is a need for a high selectivity catalyst that limits or avoids toxic leaching.
Extended operation may be limited due to the concentration of the catalyst in the reformer declining gradually, from gradual overflowing of the system with active catalyst and gradual leaching out of catalyst with exhaust gas, water and formic acid vapors. This will result a gradual decreasing of hydrogen production rate and eventually potential insufficient formation of hydrogen to obtain a maximum output from an attached fuel cell. There is a need for a high selectivity solid catalyst that extends the effective operating time of the catalyst.
Typical liquid based ruthenium metal complex catalyst is challenging to be reconditioned (reactivate, purified) and recycled after contaminated with foreign impurities (coming from formic acid and other construction materials). Impure catalyst may decompose gradually and be inactive eventually. When this occurs, the inactive catalyst mixture has to be discarded and the reformer has to be refilled with brand new catalyst mixture or whole reformer has to be discarded.
There is a need for a high selectivity solid catalyst that is convenient for recycling and safe in disposal.
Immobilization of liquid based ruthenium metal complex catalyst may be considered, however may result in less reactivity due to several reasons.
(a) Low heat transfer throughout the system.
3 (b) Less accessibility of fuel (formic acid) molecules to the active sites of the catalyst.
(c) Degradation of associated materials within a short period of time due to high acidity and high temperature of the system. These degraded byproducts eventually become a liquid and cause the decomposition of the catalyst.
(d) This immobilized system does not stop the leaching out of the catalyst from the system.
Ruthenium based hydrogen reforming catalysts are not available for use in the solid form. Therefore, application of these catalysts to build micro scale reactors having orientation independence is an expensive, potentially inefficient and challenging as described. There is a need for a convenient high sensitivity catalyst in solid form suitable for molding and forming easily.
Summary A heterogeneous polymer bound solid metal complex catalyst is provided, for reforming, particularly of hydrogen from formic acid. This noble metal complex catalyst consists of triarylphosphine ligands and at least one of them is chemically bonded to a polymer backbone. In a preferred example, the triarylphosphine ligands are triphenylphosphine ligands and at least one phenyl group is sulfonated and at least one triphenylphosphine is chemically bonded to a polymer backbone. In a preferred example this polymer bound triphenylphosphine is polymer bound Triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt (TPPTS).
In another preferred embodiment, the noble metal is ruthenium, the organic-polymer is polystyrene, and the ruthenium complex is one of Ru(H20)4(PS-TPPTS)2 and Ru(H20)4(PS-TPPTS)(TPPTS), and at least one of the sulfonated triphenylphosphine molecules is chemically bonded to the polymer backbone from para-position of its associated phenyl group, to form a rigid solid catalyst.
The heterogeneous solid metal complex catalyst provides benefits of being hydrophilic for efficient surface reaction, insoluble in water and formic acid, and chemically binding the catalyst to polymer backbone. That inhibits the catalyst leaching out from the reactor/reformer when wetted. An additional benefit is the
(c) Degradation of associated materials within a short period of time due to high acidity and high temperature of the system. These degraded byproducts eventually become a liquid and cause the decomposition of the catalyst.
(d) This immobilized system does not stop the leaching out of the catalyst from the system.
Ruthenium based hydrogen reforming catalysts are not available for use in the solid form. Therefore, application of these catalysts to build micro scale reactors having orientation independence is an expensive, potentially inefficient and challenging as described. There is a need for a convenient high sensitivity catalyst in solid form suitable for molding and forming easily.
Summary A heterogeneous polymer bound solid metal complex catalyst is provided, for reforming, particularly of hydrogen from formic acid. This noble metal complex catalyst consists of triarylphosphine ligands and at least one of them is chemically bonded to a polymer backbone. In a preferred example, the triarylphosphine ligands are triphenylphosphine ligands and at least one phenyl group is sulfonated and at least one triphenylphosphine is chemically bonded to a polymer backbone. In a preferred example this polymer bound triphenylphosphine is polymer bound Triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt (TPPTS).
In another preferred embodiment, the noble metal is ruthenium, the organic-polymer is polystyrene, and the ruthenium complex is one of Ru(H20)4(PS-TPPTS)2 and Ru(H20)4(PS-TPPTS)(TPPTS), and at least one of the sulfonated triphenylphosphine molecules is chemically bonded to the polymer backbone from para-position of its associated phenyl group, to form a rigid solid catalyst.
The heterogeneous solid metal complex catalyst provides benefits of being hydrophilic for efficient surface reaction, insoluble in water and formic acid, and chemically binding the catalyst to polymer backbone. That inhibits the catalyst leaching out from the reactor/reformer when wetted. An additional benefit is the
4 polymer bound solid metal complex catalyst can be conveniently formed into designs suitable for reformers.
A method of producing a heterogeneous solid ruthenium complex catalyst is provided, in a first step preparing polystyrene bonded TPPTS by the steps of reacting polystyrene bonded triphenylphosphine with fuming sulphuric acid, then reacting with sodium hydroxide to form polystyrene bonded TPPTS. Secondly reacting an aqueous solution of ruthenium (iii) chloride with polystyrene bonded TPPTS and TPPTS to form polystyrene bonded ruthenium /TPPTS complex, followed by a step of activation of catalyst by reacting with a mixture of sodium formate and formic acid.
Detailed Description A new class of aqueous catalysts has recently been described for low temperature hydrogen production from hydrocarbon fuels, including formic acid.
The research groups of Laurenczy [8131 patent] and Beller [Topics in Catalysis, Volume 53, Numbers 13-14, August 2010 , pp. 902-914(13), Catalytic generation of hydrogen from formic acid and its derivatives] simultaneously discovered metal complexes reacting in liquid form and displaying unusually high activity towards formic acid decomposition. Common to both is that high purity hydrogen is produced via high selectivity towards the dehydrogenation pathway (eq. A), with little or no CO production through dehydration (eq. B).
This quality makes such new catalyst formulations potentially suitable for use in fuel cell applications, where CO content of the fuel gas can cause rapid deactivation. Specifically ruthenium formulations have achieved good yields of > 95% conversion from formic acid at fast rates suitable for use in real-time power applications. This catalyst composition results in the conversion of a dehydrogenatable pre-cursor in an aqueous solution at high conversion rates of near pure H2 for an extended period of time. However, liquid form catalyst and associated homogenous reactions may by their structure and form, have the described challenges and limitations of being orientation dependent, non-hydrophilic, challenging to immobilize, degradation of catalyst concentration over time, leaching of toxic metals as discussed previously, that present major barriers to implementing in a reformer reactor system.
A novel solid catalyst and process is provided to reform formic acid and other hydrocarbons at low temperature via a selective reaction path similar to the aqueous catalyst. The solid catalyst is chemically and permanently bound to the polystyrene back bone and can be used in different forms such as fine powder, particles, sheets, rods, flakes, beads, tubes, blocks, etc. Therefore, leaching out of the catalyst from the reformer does not occur. This compound is hydrophilic but insoluble in water, formic acid and other solvents. The solid catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the solid catalyst is ideal for the building of orientation independent reformers. Moreover, used and contaminated catalyst can be easily purified, reconditioned and reused with its original activity.
The present embodiments are described using terms of definitions below:
"Catalysis," as the term used herein, is the acceleration of any physical or chemical or biological reaction by a small quantity of a substance-herein referred to as "catalyst"-the amount and nature of which remain essentially unchanged during the reaction. For teachings contained herein, a raw material is considered catalyzed by a substance into a product if the substance is a catalyst for one or more intermediate steps of associated physical or chemical or biological reaction.
"Chemical transformation," as the term used herein, is the rearrangement, change, addition, or removal of chemical bonds in any substance or substances such as but not limiting to compounds, chemicals, materials, fuels, pollutants, biomaterials, biochemicals, and biologically active species. The terms also includes bonds that some in the art prefer to not call as chemical bonds such as but not limiting to Van der Waals bonds and hydrogen bonds.
"Activity" of a catalyst, as the term used herein, is a measure of the rate of conversion of the starting material by the catalyst.
"Selectivity" of a catalyst, as the term used herein, is a measure of the relative rate of formation of each product from two or more competing reactions.
Often, selectivity of a specific product is of interest, though multiple products may interest some applications.
"Stability" of a catalyst, as the term used herein, is a measure of the catalyst's ability to retain useful life, activity and selectivity above predetermined levels in presence of factors that can cause chemical, thermal, or mechanical degradation or decomposition. Illustrative, but not limiting, factors include coking, poisoning, oxidation, reduction, thermal run away, expansion-contraction, flow, handling, and charging of catalyst.
"TPPTS" is [Triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt].
Equivalently this may be called by other names such as triphenyl phosphine trisulfonate sodium salt, trisulfonated triphenylphosphine or tris(3-sulfophenyl)phosphine trisodium salt, P(06H4-3-S03-Na)3.
For H2 use in hydrogen fuel cells, it is important to have a hydrogen gas production process producing high purity hydrogen on demand at acceptable pressures, as carbon monoxide is poisonous to the catalyst in most fuel cells.
Formic acid decomposition has two paths, dehydrogenation producing H2 and CO2, or dehydration producing CO and H20, as shown in the eq. A and B, previously. Effective reforming of formic acid for fuel cells, then benefits from highly selective dehydrogenation for increased H2 yield and low levels of CO
which is poisonous to most PEM cells. Ruthenium based metal complexes in homogenous catalysis are known to achieve fast and selective formic acid decomposition without formation of carbon monoxide. However, known catalysts exist only in liquid form.
It is now discovered that a polymer bound solid metal complex catalyst having the following general structure (1) is capable of decomposing formic acid to H2 at low temperature, Ri X X
X X
(1) In this embodiment of the catalyst, R1 and R2 can be the same or different ligands. The central Metal (M) atom is coordinated to four electron donating molecules or atoms (X) and two molecules of substituted triaryphosphine (R1 and R2) as a metal complex. The central atom (M) can be substituted with any noble metal such as rhodium, palladium, silver, osmium, iridium, platinum or gold, and ruthenium is preferred. X can be identical ligand or different types, but four molecules of H20 are preferred.
The general structures of Ri and R2 are;
F DAB
Rt 40 F ) P Pol Na002S G C S020Na (2) ED AB
AB
R2 F 1110 P 14110 Poi ()I. F 4.40) P 4 4110 H
N aGO2S G C $020Na Na002S G C S02ONa 2 (3) where A, B, C, D, E, F, G can be Hydrogen or any other functional group, and Poi is a polymer attached to either ortho, meta or para position of one phenyl group. In one embodiment Ri and R2 are identical, but only one may be needed to be polymer bound in a minimum example.
IR, and R2 are preferably substituted triphenylphosphine. At least IR, or R2 or both bound to a polymer structure. Triphenylphosphine can be mono, di or tri substituted at ortho, para or meta positions. A Polymer bound triphenylphosphine with meta tri substituted functional groups is represented by the following general structure (4);
Y (00 P Y
PcI
(4) and where Pol represents an organic polymer preferably polystyrene (PS) polymer backbone. Additionally, Y represents functional groups on the phenyl groups that have an effect on the dehydrogenation of formic acid to produce H2.
Substitutions (Y) of phosphine can be one of amines, carboxylic acids, salt of carboxylic acid, carbonyl derivatives, hydroxyl, sulfonic acid or salt of sulfonic acid including lithium, sodium, potassium, rubidium and cesium salts. The preferred substituent is meta trisulphonated sodium. The polymer bound meta-trisulfonated triphenylphosphine trisodium (Pol-TPPTS) is the preferred ligand. Preferably both ligand molecules, or at least one of them is chemically bonded to the polymer backbone from ortho, meta or para-positions of the one phenyl group in the substituted triphenylphosphine. The preferred bonding is para-position of a phenyl group in the substituted triphenyl phosphine with polymer backbone. Bonding of the polymer and substituted triphenylphosphine molecule can be formed via C-C, C-O-C, C-N-C or C-S-C bonds. The preferred linkage is C-C. Due to this chemical bond the whole molecule becomes water insoluble.
The preferred structure of polystyrene bound TPPTS (PS-TPPTS) is represented by the following (5), = P S020Na PS
S020Na
A method of producing a heterogeneous solid ruthenium complex catalyst is provided, in a first step preparing polystyrene bonded TPPTS by the steps of reacting polystyrene bonded triphenylphosphine with fuming sulphuric acid, then reacting with sodium hydroxide to form polystyrene bonded TPPTS. Secondly reacting an aqueous solution of ruthenium (iii) chloride with polystyrene bonded TPPTS and TPPTS to form polystyrene bonded ruthenium /TPPTS complex, followed by a step of activation of catalyst by reacting with a mixture of sodium formate and formic acid.
Detailed Description A new class of aqueous catalysts has recently been described for low temperature hydrogen production from hydrocarbon fuels, including formic acid.
The research groups of Laurenczy [8131 patent] and Beller [Topics in Catalysis, Volume 53, Numbers 13-14, August 2010 , pp. 902-914(13), Catalytic generation of hydrogen from formic acid and its derivatives] simultaneously discovered metal complexes reacting in liquid form and displaying unusually high activity towards formic acid decomposition. Common to both is that high purity hydrogen is produced via high selectivity towards the dehydrogenation pathway (eq. A), with little or no CO production through dehydration (eq. B).
This quality makes such new catalyst formulations potentially suitable for use in fuel cell applications, where CO content of the fuel gas can cause rapid deactivation. Specifically ruthenium formulations have achieved good yields of > 95% conversion from formic acid at fast rates suitable for use in real-time power applications. This catalyst composition results in the conversion of a dehydrogenatable pre-cursor in an aqueous solution at high conversion rates of near pure H2 for an extended period of time. However, liquid form catalyst and associated homogenous reactions may by their structure and form, have the described challenges and limitations of being orientation dependent, non-hydrophilic, challenging to immobilize, degradation of catalyst concentration over time, leaching of toxic metals as discussed previously, that present major barriers to implementing in a reformer reactor system.
A novel solid catalyst and process is provided to reform formic acid and other hydrocarbons at low temperature via a selective reaction path similar to the aqueous catalyst. The solid catalyst is chemically and permanently bound to the polystyrene back bone and can be used in different forms such as fine powder, particles, sheets, rods, flakes, beads, tubes, blocks, etc. Therefore, leaching out of the catalyst from the reformer does not occur. This compound is hydrophilic but insoluble in water, formic acid and other solvents. The solid catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the solid catalyst is ideal for the building of orientation independent reformers. Moreover, used and contaminated catalyst can be easily purified, reconditioned and reused with its original activity.
The present embodiments are described using terms of definitions below:
"Catalysis," as the term used herein, is the acceleration of any physical or chemical or biological reaction by a small quantity of a substance-herein referred to as "catalyst"-the amount and nature of which remain essentially unchanged during the reaction. For teachings contained herein, a raw material is considered catalyzed by a substance into a product if the substance is a catalyst for one or more intermediate steps of associated physical or chemical or biological reaction.
"Chemical transformation," as the term used herein, is the rearrangement, change, addition, or removal of chemical bonds in any substance or substances such as but not limiting to compounds, chemicals, materials, fuels, pollutants, biomaterials, biochemicals, and biologically active species. The terms also includes bonds that some in the art prefer to not call as chemical bonds such as but not limiting to Van der Waals bonds and hydrogen bonds.
"Activity" of a catalyst, as the term used herein, is a measure of the rate of conversion of the starting material by the catalyst.
"Selectivity" of a catalyst, as the term used herein, is a measure of the relative rate of formation of each product from two or more competing reactions.
Often, selectivity of a specific product is of interest, though multiple products may interest some applications.
"Stability" of a catalyst, as the term used herein, is a measure of the catalyst's ability to retain useful life, activity and selectivity above predetermined levels in presence of factors that can cause chemical, thermal, or mechanical degradation or decomposition. Illustrative, but not limiting, factors include coking, poisoning, oxidation, reduction, thermal run away, expansion-contraction, flow, handling, and charging of catalyst.
"TPPTS" is [Triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt].
Equivalently this may be called by other names such as triphenyl phosphine trisulfonate sodium salt, trisulfonated triphenylphosphine or tris(3-sulfophenyl)phosphine trisodium salt, P(06H4-3-S03-Na)3.
For H2 use in hydrogen fuel cells, it is important to have a hydrogen gas production process producing high purity hydrogen on demand at acceptable pressures, as carbon monoxide is poisonous to the catalyst in most fuel cells.
Formic acid decomposition has two paths, dehydrogenation producing H2 and CO2, or dehydration producing CO and H20, as shown in the eq. A and B, previously. Effective reforming of formic acid for fuel cells, then benefits from highly selective dehydrogenation for increased H2 yield and low levels of CO
which is poisonous to most PEM cells. Ruthenium based metal complexes in homogenous catalysis are known to achieve fast and selective formic acid decomposition without formation of carbon monoxide. However, known catalysts exist only in liquid form.
It is now discovered that a polymer bound solid metal complex catalyst having the following general structure (1) is capable of decomposing formic acid to H2 at low temperature, Ri X X
X X
(1) In this embodiment of the catalyst, R1 and R2 can be the same or different ligands. The central Metal (M) atom is coordinated to four electron donating molecules or atoms (X) and two molecules of substituted triaryphosphine (R1 and R2) as a metal complex. The central atom (M) can be substituted with any noble metal such as rhodium, palladium, silver, osmium, iridium, platinum or gold, and ruthenium is preferred. X can be identical ligand or different types, but four molecules of H20 are preferred.
The general structures of Ri and R2 are;
F DAB
Rt 40 F ) P Pol Na002S G C S020Na (2) ED AB
AB
R2 F 1110 P 14110 Poi ()I. F 4.40) P 4 4110 H
N aGO2S G C $020Na Na002S G C S02ONa 2 (3) where A, B, C, D, E, F, G can be Hydrogen or any other functional group, and Poi is a polymer attached to either ortho, meta or para position of one phenyl group. In one embodiment Ri and R2 are identical, but only one may be needed to be polymer bound in a minimum example.
IR, and R2 are preferably substituted triphenylphosphine. At least IR, or R2 or both bound to a polymer structure. Triphenylphosphine can be mono, di or tri substituted at ortho, para or meta positions. A Polymer bound triphenylphosphine with meta tri substituted functional groups is represented by the following general structure (4);
Y (00 P Y
PcI
(4) and where Pol represents an organic polymer preferably polystyrene (PS) polymer backbone. Additionally, Y represents functional groups on the phenyl groups that have an effect on the dehydrogenation of formic acid to produce H2.
Substitutions (Y) of phosphine can be one of amines, carboxylic acids, salt of carboxylic acid, carbonyl derivatives, hydroxyl, sulfonic acid or salt of sulfonic acid including lithium, sodium, potassium, rubidium and cesium salts. The preferred substituent is meta trisulphonated sodium. The polymer bound meta-trisulfonated triphenylphosphine trisodium (Pol-TPPTS) is the preferred ligand. Preferably both ligand molecules, or at least one of them is chemically bonded to the polymer backbone from ortho, meta or para-positions of the one phenyl group in the substituted triphenylphosphine. The preferred bonding is para-position of a phenyl group in the substituted triphenyl phosphine with polymer backbone. Bonding of the polymer and substituted triphenylphosphine molecule can be formed via C-C, C-O-C, C-N-C or C-S-C bonds. The preferred linkage is C-C. Due to this chemical bond the whole molecule becomes water insoluble.
The preferred structure of polystyrene bound TPPTS (PS-TPPTS) is represented by the following (5), = P S020Na PS
S020Na
(5) where PS represents the polystyrene polymer backbone. The meta-positions of the all phenyl groups in PS-TPPTS are sulfonated and exist as sodium salts. Because of these sodium sulphonate functional groups, the catalyst molecule attached to the system is hydrophilic. This is beneficial to carry out the formic acid reforming reaction effectively on the surface of the solid support.
Polystyrenes are hydrophobic, water insoluble and immobilized. Therefore, the polymer bound catalyst system is water insoluble and immobilized.
Because of this solid nature of the polymer bound metal complex catalyst, the reforming reaction can be performed effectively in the presence of a hydrocarbon fuel such as formic acid, in a reformer (not shown) under partially wet conditions (partially dry) in packed systems. This is a beneficial characteristic for the development of orientation independent reformers since there is no overflowing of liquids. Because liquid is limited in the reformer system using polymer bound solid metal complex catalyst.
The polystyrene polymer to which the active noble metal complex catalyst is bonded can be any water insoluble polymer of sufficient molecular weight to contain the levels of metal desired in the reforming reaction desired.
Representative examples of acceptable polystyrenes include styrene copolymer, or modified styrene from Dow Chemical Company. In general, the backbone can be comprised of any cross linked or macroreticular polymer having triarylphosphine molecules. However, polystyrene containing triphenylphosphine polymers are preferred.
The polymer bound metal complex catalyst is a heterogeneous catalyst, where the phase of the catalyst (solid) is different from the phase of the reactants (liquid). When used in reforming of formic acid, a similar rate of production of H2 to systems using aqueous only catalyst is observed in a similar volume, i.e.
the activity is substantially the same, providing the high selectivity and fast rates of aqueous catalyst in a solid phase with improved safety and orientation free operation.
An additional benefit of the polymer bound solid metal complex catalyst is minimizing or avoiding catalyst leaching, and adverse effects related to the catalyst leaching (environmental toxicity, damage and poisoning of hydrogen fuel cell and insufficient formation of hydrogen due to lack of enough active catalyst).
Due to the insoluble solid nature of the polymer bound metal complex catalyst and as the active metal complex catalyst is permanently and chemically bound to the polymer, the leaching out of the catalyst from the system is substantially avoided.
Following use of the catalyst in reforming cycles, the polymer bound solid metal complex catalyst is contaminated with impurities, requiring conditioning.
Unlike liquid form catalyst which may require specialized disposal or chemical processing, a benefit of the polymer bound solid metal complex catalyst is that the solid particles are conveniently recycled and reconditioned by suspension in water (cleaning) followed by simple filtration of the purified solid followed by reactivation. The reconditioned catalysts can be reused instead of disposed.
In the preferred embodiment, using polymer back bone, the polymer bound solid metal complex catalyst can be molded into different shapes and sizes such as catalyst powder, particles, sheets, rods, flakes, beads, tubes, blocks etc.
Such structures are convenient for advanced and safer reformers.
Additionally, the polymer bound solid metal complex catalyst can be blended with other co-polymers or can be used for coating other structures or supports.
An alternate structure of the polymer bound solid metal complex catalyst has mixed ligand and has the general structure (6), RI
Ru
Polystyrenes are hydrophobic, water insoluble and immobilized. Therefore, the polymer bound catalyst system is water insoluble and immobilized.
Because of this solid nature of the polymer bound metal complex catalyst, the reforming reaction can be performed effectively in the presence of a hydrocarbon fuel such as formic acid, in a reformer (not shown) under partially wet conditions (partially dry) in packed systems. This is a beneficial characteristic for the development of orientation independent reformers since there is no overflowing of liquids. Because liquid is limited in the reformer system using polymer bound solid metal complex catalyst.
The polystyrene polymer to which the active noble metal complex catalyst is bonded can be any water insoluble polymer of sufficient molecular weight to contain the levels of metal desired in the reforming reaction desired.
Representative examples of acceptable polystyrenes include styrene copolymer, or modified styrene from Dow Chemical Company. In general, the backbone can be comprised of any cross linked or macroreticular polymer having triarylphosphine molecules. However, polystyrene containing triphenylphosphine polymers are preferred.
The polymer bound metal complex catalyst is a heterogeneous catalyst, where the phase of the catalyst (solid) is different from the phase of the reactants (liquid). When used in reforming of formic acid, a similar rate of production of H2 to systems using aqueous only catalyst is observed in a similar volume, i.e.
the activity is substantially the same, providing the high selectivity and fast rates of aqueous catalyst in a solid phase with improved safety and orientation free operation.
An additional benefit of the polymer bound solid metal complex catalyst is minimizing or avoiding catalyst leaching, and adverse effects related to the catalyst leaching (environmental toxicity, damage and poisoning of hydrogen fuel cell and insufficient formation of hydrogen due to lack of enough active catalyst).
Due to the insoluble solid nature of the polymer bound metal complex catalyst and as the active metal complex catalyst is permanently and chemically bound to the polymer, the leaching out of the catalyst from the system is substantially avoided.
Following use of the catalyst in reforming cycles, the polymer bound solid metal complex catalyst is contaminated with impurities, requiring conditioning.
Unlike liquid form catalyst which may require specialized disposal or chemical processing, a benefit of the polymer bound solid metal complex catalyst is that the solid particles are conveniently recycled and reconditioned by suspension in water (cleaning) followed by simple filtration of the purified solid followed by reactivation. The reconditioned catalysts can be reused instead of disposed.
In the preferred embodiment, using polymer back bone, the polymer bound solid metal complex catalyst can be molded into different shapes and sizes such as catalyst powder, particles, sheets, rods, flakes, beads, tubes, blocks etc.
Such structures are convenient for advanced and safer reformers.
Additionally, the polymer bound solid metal complex catalyst can be blended with other co-polymers or can be used for coating other structures or supports.
An alternate structure of the polymer bound solid metal complex catalyst has mixed ligand and has the general structure (6), RI
Ru
(6) where Ri is polystyrene bound TPPTS as previous and R2 is TPPTS that may be aqueous or bound as solid, R1 and R2 having structures, Na0025 Na002S
P SO2ON a P S020Na PS
SO2ON a $0?0N a R, R2
P SO2ON a P S020Na PS
SO2ON a $0?0N a R, R2
(7) (8) and (6) is an effective solid catalyst for the dehydrogenation of formic acid to produce H2.
In this alternate embodiment, one of the TPPTS ligands, R1 is chemically bonded to the polystyrene backbone from the para-position of one phenyl group in TPPTS. The other TPPTS ligand, R2 may be in an aqueous form during the synthesis but is bound as a solid after synthesis.
The polymer bound solid metal complex catalyst achieves significant benefits, particularly for reforming hydrocarbons efficiently and reliably.
First, due to the meta-position of all associated phenyl groups of TPPTS molecule being sulfonated, the solid ruthenium complex catalyst is hydrophilic for efficient surface reaction. Secondly unlike aqueous catalyst, the polymer bound solid ruthenium complex catalyst is inhibited from leaching out from the reactor when wetted during reforming. Third, the solid metal complex catalyst is insoluble in water (and formic acid), maintaining it's properties over longer term use and storage.
Compared to known high selectivity liquid form catalysts and processes for formic acid reforming, the polymer bound solid metal complex catalyst enables orientation insensitive reforming when maintained wet, safe with no leaching, and the ability to recycle used catalyst. The catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the catalyst is ideal for orientation independent reformers.
A general method for preparing polymer bound heterogeneous solid metal TPPTS complex catalyst, includes the chemical transformation steps of (a) Reacting organic polymer bonded triphenyl phosphine with fuming sulphuric acid followed by reacting with sodium hydroxide to form polymer bonded TPPTS (b) Reacting an aqueous solution of noble metal reagent with polymer bonded TPPTS and a second TPPTS to form polymer bound heterogeneous solid metal complex. and (c) Activation of polymer bound heterogeneous solid metal complex to form activated solid metal complex catalyst.
For the preferred solid polystyrene bound ruthenium complex catalyst, a preferred method of preparing the catalyst, includes a first step of preparing polystyrene bonded TPPTS (TPPTS-PS) as shown in Scheme 1. A portion of this chemical transformation method is similar to that discussed for the preparation of TPPTS from triphenylphosphine by Hida et.al in J. Coord. Chem., 1998, Vol. 43, 345-348. The new preparation method Scheme 1 Na00,?S
40 (1) Fuming H2804 (2) Isiii011 S020Na S020Na Polystyrene hound triphettylphosphinn TPPTS-PS
shows the sub steps of (i) Reacting polystyrene bonded triphenylphosphine with fuming sulphuric acid, and (ii) secondly reacting with sodium hydroxide to form polystyrene bonded TPPTS.
In the second step, an aqueous solution of ruthenium (iii) chloride (RuC13) is reacted with the polystyrene bonded TPPTS and regular TPPTS stepwise to form polystyrene bonded ruthenium/TPPTS complex. This solid metal complex is then separated from the liquid.
In a third step the polymer bound metal complex is activated by reacting with sodium formate and formic acid to form activated metal complex catalyst.
Finally the solid product is dried under vacuum.
An embodiment of the process is more clearly described in the example shown below.
Example Fuming sulfuric acid (contained 18-24% free SO3) was obtained from Alfa-Aesar.
Acetone was obtained from Aldrich and degassed prior to use. Water was filtered through Millipore filtration system and degassed prior to use. Sodium hydroxide, Polystyrene bound triphenylphosphine (contain 3 mmol/g), triphenylphosphine, Ruthenium (iii) chloride (RuC13), and Sodium formate were obtained from Aldrich and used without purification. Formic acid was obtained from BASF and distilled before use.
TPPTS was prepared using the method described by Hide, et.al, and product was obtained with 94% purity.
Preparation of Polystyrene bound TPPTS
Experiment was carried out in an inert atmosphere of N2. Fuming Sulfuric acid (100 mL) was put into a 1L three necked round bottomed flask and stirred in ice bath until the temperature reached 0 C. Then the solution was added polystyrene bound triphenylphosphine (10 g) and reaction mixture was stirred at 0 C for 30 min. Then the ice bath was removed and the temperature of the reaction was increased to rt. The mixture was stirred at room temperature for approximately 240 h. The mixture was cooled to 0 C and then added degassed solution of 20% sodium hydroxide carefully until the pH of the mixture became 3Ø Then the mixture is centrifuged at 3500 rpm for 10 min to separate the solid.
The liquid was discarded and the solid product was washed with degassed water (2X 400 mL) followed by degassed solution of acetone (400 mL). Finally, the solid product was dried under vacuum to obtain the product (18 g).
Preparation Polystyrene bound Ruthenium/TPPTS catalyst This preparation was conducted in an open atmosphere with proper ventilation. A solution of ruthenium (iii) chloride (0.5 g) dissolved in water (20 mL, degassed) was added formic acid (1 mL, 25 M) followed by polystyrene bound TPPTS (2.7 g) and stirred at 100 C for 30 min. Then the mixture was added TPPTS (0.5 g) and stirred at 10000 for another 10 min. Then the mixture was added slowly and portion wise a aqueous solution of sodium formate in formic acid (2 g of sodium formate in 10 mL of 12 M formic acid solution) and continued heating at 100 C. Once the vigorous gas formation is ceased, the mixture was centrifuged and the top liquid layer was discarded. The solid was washed with water and dried under vacuum. This solid catalyst is capable of producing H2 by the decomposition of formic acid and is water insoluble.
Additional noble metal complex catalyst formulations can be substituted equivalently to formulate heterogeneous polymer bound water insoluble metal complex catalyst using similar processes. An alternate embodiment has hybrids or blends of noble metal complexes substituting for the ruthenium complex.
While the embodiments are described for use with the solid ruthenium based metal complex catalyst with formic acid fuel, they may also be used in a wider range of solid catalysts for reforming hydrocarbons in general. The embodiments described herein have solved these various unmet needs in an efficient, effective and integrated manner.
While particular elements, embodiments and applications for the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.
In this alternate embodiment, one of the TPPTS ligands, R1 is chemically bonded to the polystyrene backbone from the para-position of one phenyl group in TPPTS. The other TPPTS ligand, R2 may be in an aqueous form during the synthesis but is bound as a solid after synthesis.
The polymer bound solid metal complex catalyst achieves significant benefits, particularly for reforming hydrocarbons efficiently and reliably.
First, due to the meta-position of all associated phenyl groups of TPPTS molecule being sulfonated, the solid ruthenium complex catalyst is hydrophilic for efficient surface reaction. Secondly unlike aqueous catalyst, the polymer bound solid ruthenium complex catalyst is inhibited from leaching out from the reactor when wetted during reforming. Third, the solid metal complex catalyst is insoluble in water (and formic acid), maintaining it's properties over longer term use and storage.
Compared to known high selectivity liquid form catalysts and processes for formic acid reforming, the polymer bound solid metal complex catalyst enables orientation insensitive reforming when maintained wet, safe with no leaching, and the ability to recycle used catalyst. The catalyst is stable to high temperatures, and also stable to acidic and basic conditions. Because of the solid nature, the catalyst is ideal for orientation independent reformers.
A general method for preparing polymer bound heterogeneous solid metal TPPTS complex catalyst, includes the chemical transformation steps of (a) Reacting organic polymer bonded triphenyl phosphine with fuming sulphuric acid followed by reacting with sodium hydroxide to form polymer bonded TPPTS (b) Reacting an aqueous solution of noble metal reagent with polymer bonded TPPTS and a second TPPTS to form polymer bound heterogeneous solid metal complex. and (c) Activation of polymer bound heterogeneous solid metal complex to form activated solid metal complex catalyst.
For the preferred solid polystyrene bound ruthenium complex catalyst, a preferred method of preparing the catalyst, includes a first step of preparing polystyrene bonded TPPTS (TPPTS-PS) as shown in Scheme 1. A portion of this chemical transformation method is similar to that discussed for the preparation of TPPTS from triphenylphosphine by Hida et.al in J. Coord. Chem., 1998, Vol. 43, 345-348. The new preparation method Scheme 1 Na00,?S
40 (1) Fuming H2804 (2) Isiii011 S020Na S020Na Polystyrene hound triphettylphosphinn TPPTS-PS
shows the sub steps of (i) Reacting polystyrene bonded triphenylphosphine with fuming sulphuric acid, and (ii) secondly reacting with sodium hydroxide to form polystyrene bonded TPPTS.
In the second step, an aqueous solution of ruthenium (iii) chloride (RuC13) is reacted with the polystyrene bonded TPPTS and regular TPPTS stepwise to form polystyrene bonded ruthenium/TPPTS complex. This solid metal complex is then separated from the liquid.
In a third step the polymer bound metal complex is activated by reacting with sodium formate and formic acid to form activated metal complex catalyst.
Finally the solid product is dried under vacuum.
An embodiment of the process is more clearly described in the example shown below.
Example Fuming sulfuric acid (contained 18-24% free SO3) was obtained from Alfa-Aesar.
Acetone was obtained from Aldrich and degassed prior to use. Water was filtered through Millipore filtration system and degassed prior to use. Sodium hydroxide, Polystyrene bound triphenylphosphine (contain 3 mmol/g), triphenylphosphine, Ruthenium (iii) chloride (RuC13), and Sodium formate were obtained from Aldrich and used without purification. Formic acid was obtained from BASF and distilled before use.
TPPTS was prepared using the method described by Hide, et.al, and product was obtained with 94% purity.
Preparation of Polystyrene bound TPPTS
Experiment was carried out in an inert atmosphere of N2. Fuming Sulfuric acid (100 mL) was put into a 1L three necked round bottomed flask and stirred in ice bath until the temperature reached 0 C. Then the solution was added polystyrene bound triphenylphosphine (10 g) and reaction mixture was stirred at 0 C for 30 min. Then the ice bath was removed and the temperature of the reaction was increased to rt. The mixture was stirred at room temperature for approximately 240 h. The mixture was cooled to 0 C and then added degassed solution of 20% sodium hydroxide carefully until the pH of the mixture became 3Ø Then the mixture is centrifuged at 3500 rpm for 10 min to separate the solid.
The liquid was discarded and the solid product was washed with degassed water (2X 400 mL) followed by degassed solution of acetone (400 mL). Finally, the solid product was dried under vacuum to obtain the product (18 g).
Preparation Polystyrene bound Ruthenium/TPPTS catalyst This preparation was conducted in an open atmosphere with proper ventilation. A solution of ruthenium (iii) chloride (0.5 g) dissolved in water (20 mL, degassed) was added formic acid (1 mL, 25 M) followed by polystyrene bound TPPTS (2.7 g) and stirred at 100 C for 30 min. Then the mixture was added TPPTS (0.5 g) and stirred at 10000 for another 10 min. Then the mixture was added slowly and portion wise a aqueous solution of sodium formate in formic acid (2 g of sodium formate in 10 mL of 12 M formic acid solution) and continued heating at 100 C. Once the vigorous gas formation is ceased, the mixture was centrifuged and the top liquid layer was discarded. The solid was washed with water and dried under vacuum. This solid catalyst is capable of producing H2 by the decomposition of formic acid and is water insoluble.
Additional noble metal complex catalyst formulations can be substituted equivalently to formulate heterogeneous polymer bound water insoluble metal complex catalyst using similar processes. An alternate embodiment has hybrids or blends of noble metal complexes substituting for the ruthenium complex.
While the embodiments are described for use with the solid ruthenium based metal complex catalyst with formic acid fuel, they may also be used in a wider range of solid catalysts for reforming hydrocarbons in general. The embodiments described herein have solved these various unmet needs in an efficient, effective and integrated manner.
While particular elements, embodiments and applications for the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.
Claims (24)
1. A heterogeneous polymer bound solid metal complex catalyst for reforming hydrogen from formic acid, comprising, a noble metal complex comprising two or more triarylphosphine ligands, wherein at least one of the two or more triarylphosphine ligands is chemically bonded to a polymer by an aryl group of the at least one triarylphosphine ligand.
2. The solid metal complex catalyst of claim 1, wherein the two or more triarylphosphine ligands are triphenyl phosphine ligands and at least one phenyl group of the two or more triphenyl phosphine ligands is sulfonated.
3. The solid metal complex catalyst of claim 2. wherein the triphenyl phosphine ligand chemically bonded to the polymer is triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt (TPPTS).
4. The solid metal complex catalyst of claim 1, 2 or 3, wherein the noble metal is ruthenium, rhodium, palladium, silver, osmium, iridium, platinum or gold.
5. The solid metal complex catalyst of claim 1, 2 or 3, wherein said noble metal is ruthenium.
6. The solid metal complex catalyst of any one of claims 1 to 5, wherein said polymer is polystyrene.
7. The solid metal complex catalyst of claim 1, wherein the solid metal complex catalyst is Ru(H2O)4(PS-TPPTS)2 or Ru(H2O)4(PS-TPPTS)(TPPTS), wherein PS is polystyrene and TPPTS is triphenylphosphine-3,3',3"-trisulfonic acid trisodium salt.
8. The solid metal complex catalyst of claim 1, wherein the at least one of the two or more triarylphosphine ligands is chemically bonded to the polymer from at least one of the ortho, meta or para-positions of the aryl group.
9. The solid metal complex catalyst of claim 1, wherein the at least one of the two or more triarylphosphine ligands is chemically bonded to the polymer from a para-position of the aryl group.
10. The solid metal complex catalyst of claim 1, wherein said noble metal is ruthenium and the two or more triarylphosphine ligands are TPPTS, and wherein meta-positions of the phenyl groups of TPPTS are sulfonated.
11. The solid metal complex catalyst of claim 10, wherein the sulfonated phenyl groups of TPPTS are sodium salts.
12. The solid metal complex catalyst of any one of claims 1 to 11, wherein the solid metal complex catalyst is insoluble in water, formic acid or both water and formic acid.
13. The solid metal complex catalyst of any one of claims 1 to 12, wherein the solid metal complex catalyst is inhibited from leaching out from a reformer or a reactor when wetted.
14. The solid metal complex catalyst of any one of claims 1 to 13, wherein the solid metal complex catalyst is formed one from molded shapes, powder, particles, sheets, rods, flakes, beads, tubes, blended polymers or blocks.
15. The solid metal complex catalyst of any one of claims 1 to 14, further comprising water and formic acid.
16. The solid metal complex catalyst of any one of claims 1 to 15, wherein the solid metal complex catalyst is hydrophilic.
17. The solid metal complex catalyst of any one of claims 1 to 16, wherein the solid metal complex catalyst is a rigid solid catalyst.
18. A method of producing a heterogeneous solid ruthenium complex catalyst, the method comprising:
a) preparing a polystyrene bonded TPPTS by the steps of reacting a polystyrene bonded triphenylphosphine with fuming sulphuric acid; and reacting with sodium hydroxide to form the polystyrene bonded TPPTS;
and b) reacting an aqueous solution of ruthenium (III) chloride with the polystyrene bonded TPPTS, forming a polystyrene bonded ruthenium/TPPTS complex; and c) activating the catalyst by reacting the polystyrene bonded ruthenium/TPPTS
complex with a mixture of sodium formate and formic acid.
a) preparing a polystyrene bonded TPPTS by the steps of reacting a polystyrene bonded triphenylphosphine with fuming sulphuric acid; and reacting with sodium hydroxide to form the polystyrene bonded TPPTS;
and b) reacting an aqueous solution of ruthenium (III) chloride with the polystyrene bonded TPPTS, forming a polystyrene bonded ruthenium/TPPTS complex; and c) activating the catalyst by reacting the polystyrene bonded ruthenium/TPPTS
complex with a mixture of sodium formate and formic acid.
19. The method of claim 18, further comprising the step of:
a. filtering and drying the catalyst.
a. filtering and drying the catalyst.
20. A method of reconditioning a heterogeneous polymer bound solid metal complex catalyst following contact and reaction with formic acid comprising the steps of:
a) suspending the heterogeneous polymer bound solid metal complex catalyst in water;
b) filtering the catalyst; and c) activating the catalyst.
a) suspending the heterogeneous polymer bound solid metal complex catalyst in water;
b) filtering the catalyst; and c) activating the catalyst.
21. The method of claim 18, wherein in step b) the aqueous solution of ruthenium (III) chloride is reacted with polystyrene bonded TPPTS and TPPTS stepwise to form the polystyrene bonded ruthenium/TPPTS complex.
22. A method of producing a heterogeneous polymer bound solid metal complex catalyst for reforming hydrogen from formic acid, the method comprising:
a) preparing a polymer bonded triarylphosphine-sulfonic acid sodium salt by the steps of:
i. reacting polymer bonded triarylphosphine with fuming sulphuric acid;
and ii. reacting a product from (i) with sodium hydroxide to form its sodium salt; and b) reacting a solution of noble metal reagent with the polymer bonded triarylphosphine-sulfonic acid sodium salt to form the heterogeneous polymer bound solid metal complex catalyst.
a) preparing a polymer bonded triarylphosphine-sulfonic acid sodium salt by the steps of:
i. reacting polymer bonded triarylphosphine with fuming sulphuric acid;
and ii. reacting a product from (i) with sodium hydroxide to form its sodium salt; and b) reacting a solution of noble metal reagent with the polymer bonded triarylphosphine-sulfonic acid sodium salt to form the heterogeneous polymer bound solid metal complex catalyst.
23. A heterogeneous polymer bound solid metal complex catalyst, of the general formula (1), where R1 and R2 are of the structure, and each of A, B, C, D, E, F, G is hydrogen, X are four ligands with electron donating ability, M is a noble metal, and Pol is a polymer attached to at least one of the ortho, meta or para positions of at least one phenyl group of R1 or R2.
24. The heterogeneous polymer bound solid metal complex catalyst of claim 23, wherein Pol is polystyrene, X is H2O and M is ruthenium.
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