WO2018223034A1

WO2018223034A1 - Catalyst and process for the production of 1,5-pentanediol

Info

Publication number: WO2018223034A1
Application number: PCT/US2018/035662
Authority: WO
Inventors: Valery Sokolovskii; Mayya LAVRENKO; Alfred Hagemeyer; Vincent J. Murphy
Original assignee: Archer-Daniels-Midland Company
Priority date: 2017-06-02
Filing date: 2018-06-01
Publication date: 2018-12-06

Abstract

The present invention relates generally to select rhodium-rhenium (Rh-Re) or iridium-rhenium (Ir-Re) catalysts and their use in processes for the catalytic hydrogenolysis of tetrahydrofurfuryl alcohol (THFA) to 1,5-pentanediol.

Description

CATALYST AND PROCESS FOR THE PRODUCTION OF 1,5-PENTANEDIOL

FIELD OF THE INVENTION

[0001] The present invention relates generally to processes for the catalytic

hydrogenolysis of tetrahyclrofurfuryl alcohol (THFA) to 1,5-pentanediol and to select rhodium- rhenium (Rh-Re) or iridium-rhenium (Ir-Re) catalysts useful therein.

BACKGROUND OF THE INVENTION

[0002] 1,5-pentanediol (PDO) is a compound mat is useful in a variety of applications, including, for example, as a component in products such as plasticizers, emulsifiers, inks and coatings, solvents, cosmetics, synthetic resins, lubricating oils, agricultural chemicals, paints, perfumes; as a monomer in the synthesis of polymers, such as polyester polyols, polyurethanes, and polycarbonates; and as a starting point in the synthesis of compounds such as, delta- valerolactone, piperidine, pyridine, glutaric acid, and glutaraldehyde.

[0003] Synthetic routes for producing 1,5-pentanediol have been described in the literature, albeit with mixed results. For example, W. Xu et al., Chem. Commun., 2011, 47, 3924-3926 describe the conversion of furfural (also known as furan-2-carbaldehyde) to 1 ,5- pentanediol, through the use of a

The reported yields and productivities are low, however, with maximum yields of only 35% after a 24 hour reaction time at 140°C. .

[0004] Koso et al., Chem. Comunn, 2009, 2035-2037 report that a rhenium-modified rhodium catalyst can selectively transform tettahydrofurfurfuryl alcohol (THFA) to 1,5- pentanediol

but productivities are not high. After a reaction time of 24 hours at 120°C, a

catalyst with a Re/Rh atomic ratio of 0.5: 1 produces a 77% yield of 1,5- PDO with a selectivity of 80%.

[0005] In a separate publication, Koso et al., J. of Catalysis., 2009, 267, 89-92 further showed that repeated use of the Rh-ReO_x/Si0₂ catalyst leads to a rapid catalyst deactivation which the authors attributed to leaching of rhenium from the catalyst.

[0006] It has also been reported that a Rh-ReO_x on activated carbon catalyst with a Re/Rh atomic ratio of 0.25:1 can selectively transform tetrahydrofiirfurfuryl alcohol (THFA) to 1,5-pentanediol. See Koso et al., ChemCatChem, 2010, 2:547-555.

[0007] A Rh-ReO_x/Carbon catalyst (Re/Rh atomic ratio of 0.5:1) has also been described by Chia et al., J. Am. Chem. Soc, 2011, 133, 12675-12689. The authors report low

productivities with 47% THFA conversion and 1,5-PDO selectivity of 97% achieved after a reaction time of 4 hours at 120°C. The authors also report the existence of rhenium leaching and catalyst deactivation under aqueous reaction conditions.

[0008] In a recent study, the same authors report an alternative approach to the conversion of furfural to 1,5-PDO in which the hydrogenolysis step for converting THFA to 1,5- PDO is avoided, based on the authors claim that the Rh-ReO_x catalysts reported in the literature possess low activities and are too costly. ChemSusChem., 2017, 10, 1-6.

[0009] Of particular value would be catalytic processes for producing 1,5-pentanediol that are more productive, selective, and stable than currently existing processes.

SUMMARY OF THE INVENTION

[0010] Briefly, therefore, the present invention is directed to processes for preparing 1,5- pentanediol, comprising reacting tetiahydrofurfuryl alcohol (THFA) with hydrogen in a reaction mixture in the presence of a heterogeneous catalyst comprising a first metal (rhodium or iridium) and rhenium on a catalyst support, to convert at least a portion of the tetiahydrofurfuryl alcohol to 1,5-pentanediol. The present invention is also directed to catalysts useful therein.

[0011] In one embodiment, the process of the present invention comprises reacting tetiahydrofurfuryl alcohol (THFA) with hydrogen in a reaction mixture in the presence of a heterogeneous catalyst to convert at least a portion of the tetiahydrofurfuryl alcohol to 1,5- pentanediol, wherein the catalyst comprises a first metal and rhenium on a catalyst support, the first metal is selected from the group consisting of rhodium and iridium and the catalyst support comprises a support material selected from the group consisting of zirconia, silicon carbide, and a carbonaceous material. When the catalyst support comprises a carbonaceous material, the catalyst has a BET specific surface area in the range of from about 50 m²/g to about 200 m²/g.

[0012] In one embodiment, the catalyst comprises a first metal and rhenium on a catalyst support, the first metal is selected from the group consisting of rhodium and iridium and the catalyst support comprises a support material selected from the group consisting of zirconia, silicon carbide, and a carbonaceous material. When the catalyst support comprises a

carbonaceous material, the catalyst has a BET specific surface area in the range of from about 50 m²/g to about 200 m²/g.

[0013] In another embodiment, the catalyst comprises a first metal and rhenium on a shaped catalyst support comprising a carbonaceous material; and a shell metal layer disposed directly adjacent to and at least partially covering the outer surface of the shaped catalyst support. The first metal is selected from the group consisting of rhodium and iridium and the shell metal layer comprises one or more metals selected from the group consisting of rhodium, iridium, rhenium, mixtures of rhodium and rhenium, and mixtures of iridium and rhenium Further, the shell metal layer is enriched in content of said one or more metals relative to the concentration of said one or more metals in regions of the catalyst other than the shell metal layer.

[0014] Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig. 1 depicts the relationship between 1,5-pentanediol yield and the BET specific surface areas of different carbon black powders used in various heterogeneous Rh-Re/C catalysts of the present invention. A description of the preparation and characterization of these catalysts is provided in Examples 1 and 2.

[0016] Fig.2 depicts results obtained from the Rh-Re/C (extrudate) catalyzed hydrogenolysis of THFA to 1,5-pentanediol over an on-stream period of 800+ hours. The 1,5- pentanediol yield (·) and 1,5 pentanediol selectivity (Δ) is shown as a function of time in hours. A description of the corresponding experiment is provided in Example 5.

[0017] Fig.3 illustrates the stability of Rh-Re/Zr catalyst over a period of 1000 hours of production of 1,5-pentanediol from THFA. The plot depicts 1,5-pentanediol yield (·) and 1,5 pentanediol selectivity (Δ) as a function of time in hours. A description of the corresponding experiment is provided in Example 9.

[0018] Fig.4 depicts results obtained from the Rh-Re/Silicon Carbide (ring) catalyzed hydrogenolysis of THFA to 1,5-pentanediol over an on-stream period of 750+ hours. The plot depicts 1,5-pentanediol yield (·) and 1,5 pentanediol selectivity (Δ) is shown as a function of time in hours. A description of the corresponding experiment is provided in Example 13.

[0019] Fig. 5 provides a micrograph of a cross section of a Rh-Re carbon (extrudate)- supported catalyst comprising a rhodium shell. Corresponding compositional values are presented in Example 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] In accordance with various embodiments of the present invention, a process is provided for preparing 1,5-pentanediol (II) by reacting tetiahydrofurfuryl alcohol (I) with hydrogen in a reaction mixture in the presence of a heterogeneous catalyst to convert at least a portion of the THFA to 1,5-pentanediol, as follows:

[0021] The present invention also provides novel catalysts that are particularly useful in these processes and which exhibit the desirable properties of high selectivity for PDO and high stability under continuous flow process conditions.

I. Catalysts for Producing 1.5-Pentanediol

[0022] The present invention provides a catalyst that is useful for catalyzing the hydrogenolysis of THFA to PDO, wherein the catalyst comprises a first metal (rhodium or iridium) and rhenium on a catalyst support. In certain embodiments, the catalyst of the present invention may further comprise a promoter metal selected from the group consisting of copper, bismuth, and combinations thereof. In various embodiments, the catalyst support comprises a material selected from the group consisting of a carbonaceous material, zirconia, and silicon carbide.

[0023] The term "carbonaceous material" refers to various allotropes of carbon, including amorphous carbon such as carbon black and activated carbon as well as crystalline forms such as graphite, charcoal, carbon nanotubes, and combinations thereof, as well as composite materials prepared therefrom The choice of carbonaceous material will depend on the desired properties for the carbon support and carbon-supported catalyst as a described in detail below. The term "carbon support" refers to a catalyst support that comprises a carbonaceous material. The term "carbon-supported catalyst" refers to a catalyst comprising a carbon support.

[0024] The catalysts of the present invention typically comprise rhenium in an amount in the range of from about 0.25 wt.% to about 6 wt.%, from about 0.5 wt.% to about 6 wt.%, from about 1 wt.% to about 6 wt.%, from about 2 wt.% to about 6 wt.%, from about 3 wt.% to about 6 wt.%, from about 3 wt.% to about 5 wt.%, or from about 4 wt.% to about 5 wt.% based on the total weight of the catalyst. Where the first metal is rhodium, the catalyst typically comprises rhodium in an amount in the range of from about 0.25 wt% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, from about 3 wt.% to about 5 wt.%, or from about 4 wt.% to about 5 wt.% based on the total weight of the catalyst. Where the first metal is iridium, the catalyst typically comprises iridium in an amount in the range of from about 0.25 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, or from about 2 wt.% to about 4 wt.% based on the total weight of the catalyst.

[0025] In certain embodiments, the catalyst may comprise a promoter metal selected from the group consisting of copper, bismuth, and combinations thereof. When the promoter metal comprises copper, the catalyst typically comprises copper in an amount in the range of from about 0.005 wt.% to about 2 wt.%, from about 0.01 wt.% to about 1 wt.%, from about 0.01 wt.% to about 0.75 wt.%, from about 0.05 wt.% to about 0.75 wt.%, from about 0.1 wt.% to about 0.75 wt.%, or from about 0.15 wt.% to about 0.75 wt.% based on the total weight of the catalyst. When the promoter metal comprises bismuth, the catalyst typically comprises bismuth in an amount in the range of from about 0.005 wt.% to about 2 wt.%, from about 0.01 wt.% to about 1 wt.%, from about 0.05 wt.% to about 1 wt.%, from about 0.05 wt.% to about 0.75 wt.%, from about 0.1 wt.% to about 0.5 wt.%, or from about 0.2 wt.% to about 0.4 wt.% based on the total weight of the catalyst.

[0026] In the rhodium-rhenium catalyst of the present invention, the weight ratio of rhenium to rhodium (Re/Rh) present in the catalyst is generally at least about 0.5: 1 , at least about 1 : 1 or at least about 1.1:1 and typically in the range of from about 0.5: 1 to about 5: 1, from about 0.6: 1 to about 4: 1, from about 0.7: 1 to about 3:1, from about 0.8: 1 to about 2: 1, or from about 0.9: 1 to about 2: 1. In certain embodiments, the weight of rhenium present exceeds the weight of rhodium present such that the rhenium to rhodium (Re/Rh) weight ratio of the catalyst is in the range of from about 1.1:1 to about 2:1, from about 1.1:1 to about 1.8:1, from about 1.1:1 to about 1.7:1, from about 1.2:1 to about 1.6:1, or from about 1.3: 1 to about 1.5: 1. In some embodiments, the Re/Rh weight ratio of the catalyst is in the range of from about 1.3:1 to about 1 :5: 1. In certain embodiments where the rhodium-rhenium catalyst comprises a promoter metal, the weight ratio of promoter metal to rhodium is typically from about 0.001 : 1 to about 0.5: 1, from about 0.002: 1 to about 0.4: 1 , or from about 0.002: 1 to about 0.3: 1. When the promoter metal is copper, the weight ratio of copper to rhodium is typically from about 0.001 : 1 to about 0.1:1, from about 0.005:1 to about 0.075:1, or from about 0.006:1 to about 0.07:1. When the promoter metal is bismuth, the weight ratio of bismuth to rhodium is typically from about 0.005:1 to about 0.5:1, from about 0.01:1 to about 0.25:1, or from about 0.015:1 to about 0.25:1.

[0027] In the iridium-rhenium catalyst of the present invention, the weight ratio of rhenium to iridium (Re/Ir) present in the catalyst is generally at least about 0.5: 1 or at least about 1 : 1, and typically in the range of from about 0.5: 1 to about 5:1, from about 0.6: 1 to about 4: 1, from about 0.7:1 to about 3:1, from about 0.8:1, to about 2:1, or from about 0.9:1 to about 2:1. In certain embodiments when the iridium-rhenium catalyst comprises a promoter metal, the weight ratio of promoter metal to iridium is typically in the range of from about 0.005: 1 to about 0.25: 1, from about 0.01 : 1 to about 0.25: 1, or from about 0.02: 1 to about 0.2: 1. When the promoter metal is copper, the weight ratio of copper to iridium is typically from about 0.005:1 to about 0.25: 1 , from about 0.01 : 1 to about 0.2: 1, or from about 0.02: 1 to about 0.17: 1. When the promoter metal is bismuth, the weight ratio of bismuth to iridium is typically from about 0.005: 1 to about 0.25: 1, from about 0.01: 1 to about 0.25: 1, from about 0.02: 1 to about 0.2: 1, or from about 0.03:1 to about 0.18:1.

[0028] In the case of carbon-supported catalysts of the present invention (and the corresponding supports) the BET specific surface area is typically in the range of from about 50 m²/g to about 200 m²/g, from about 75 m²/g to about 200 m²/g, from about 75 m²/g to about 180 m²/g, from about 75 m²/g to about 150 m²/g, from about 75 m²/g to about 125 m²/g. In certain other embodiments, the BET specific surface area may be in the range of from about 85 m²/g to about 200 m²/g, from about 85 m²/g to about 150 m²/g, or from about 85 m /g to about 125 m²/g. In certain other embodiments, the carbon-supported catalysts of the present invention (and the corresponding supports) have a BET specific surface area of about 100 nr/g. As used herein, the term "BET specific surface area" refers to specific surface area as determined from nitrogen adsorption data in accordance with the Brunauer, Emmett and Teller (BET) Theory and associated method described in S. Brunauer, P.H. Emmett, E. Teller, J. Am. Chem. Soc. 1938, 60, 309-331, and ASTM D3663-03(2008) Standard Test Method for Surface Area of Catalysts and Catalyst Carriers, which is incorporated herein by reference. The specific surface area and other physical properties (e.g., average pore diameter) of the catalysts are essentially the same as those of the supports used to prepare the catalyst.

[0029] Catalyst supports of the present invention may be mesoporous with large pores suitable for reactant absorption, selective reactivity, and product desorption. This aids in providing high levels of catalyst productivity and selectivity. Carbon-supported catalysts of the present invention (and the corresponding supports) typically have an average pore diameter from about 10 nm to about SO nm. Average pore diameters and pore volumes described herein were determined in accordance with the procedures described in E.P. Barrett, L.G. Joyner, P. P. Halenda, J. Am. Chem. Soc. 1951, 73, 373-380 and ASTM D4222-03(2008) Standard Test Method for Determination of Nitrogen Adsorption and Desorption Isotherms of Catalysts and Catalyst Carriers by Static Volumetric Measurements, which are incorporated herein by reference (referred to herein as the "BJH Method"). In certain other embodiments, the carbon- supported catalysts of the present invention (and the corresponding supports) have an average pore diameter in the range of from about 10 to about 25 nm, as determined by the BJH Method.

[0030] Catalytic performance of carbon-supported, rhodium-rhenium (Rh-Re) or iridium-rhenium (Ir-Re) catalysts appears to be sensitive to BET specific surface area. Examples 1-3 demonstrate that carbon-supported Rh-Re catalysts of the present invention, having a BET specific surface area of less than about 200 m²/g (e.g., from about 100 m²/g to about 180 m²/g), catalyze the production of 1,5-pentanediol from THFA with an enhanced combination of selectivity, yield, and catalyst productivity as compared to carbon-supported Rh-Re catalyst prepared using supports with a higher BET specific surface area.

[0031] When the support comprises zirconia or silicon carbide, the catalysts (and the corresponding supports) typically have a BET specific surface area in the range of from about 10 m²/g to about 150 m²/g. Often, these zirconia- and silicon carbide-supported catalysts (and the corresponding supports) have a BET specific surface area of at least about 10 m²/g, at least about 15 m²/g, at least about 20 m²/g, or at least about 25 m²/g. Typically, the BET specific surface area of the zirconia-supported catalysts (and the corresponding supports) is in the range of from about 10 m²/g to about 200 m²/g, from about 15 m²/g to about 175 m²/g, from about 15 m²/g to about 150 m²/g, from about 20 m²/g to about 125 m²/g, from about 25 m²/g to about 100 m²/g, from about 30 m²/g to about 75 m²/g, from about 35 m²/g to about 75 m²/g, from about 40 m²/g to about 70 m²/g, or from about 45 m²/g to about 50 m²/g. Typically, the BET specific surface area of the silicon carbide-supported catalysts (and the corresponding supports) is in the range of from about 5 m²/g to about 100 m²/g, from about 10 m²/g to about 90 m²/g, from about 10 m²/g to about 80 m²/g, from about 15 m²/g to about 70 m²/g, from about 15 m²/g to about 60 m²/g, from about 20 m²/g to about 50 m²/g, or from about 20 m²/g to about 40 m²/g.

[0032] Zirconia- and silicon carbide-supported catalysts (and the corresponding supports) typically have an average pore diameter in the range of from about 5 nm to about 150 nm. For example, zirconia-supported catalysts (and the corresponding supports) typically have an average pore diameter in the range of from about 10 nm to about 50 nm, from about 15 nm to about SO nm, from about 20 nm to about 45 nm, from about 20 nm to about 40 nm, or from about 25 nm to about 35 nm. Silicon carbide-supported catalysts (and the corresponding supports) typically have an average pore diameter in the range of from about 5 nm to about 150 nm, from about 10 nm to about 150 nm, from about 15 nm to about 150 nm, from about 20 nm to about 150 nm, from about 25 nm to about 150 nm, from about 30 nm to about 150 nm, from about 35 nm to about 150 nm, from about 40 nm to about 150 nm, from about 45 nm to about 150 nm, or from about 50 nm to about 150 nm

[0033] In certain embodiments, catalyst supports (and the resulting catalysts) used in the practice of the present invention may be in powder form (e.g., carbon black powder). Carbon black powders typically have an average particle size in the range of from about 10 nm to about 100 nm. The preparation and use of catalysts of the present invention in powdered form is illustrated in Examples 1-4 and 11.

[0034] Alternatively, the catalyst supports may be in a "shaped" form, such as, for example, granules, pellets, spheres, extrudates, rings, and the like, wherein powders, powder/binder formulations, or other powder-containing composite formulation, are shaped into relatively larger forms by any of a variety of known techniques, such as, for example, calendaring, granulation, injection molding, extrusion, and the like, followed by optional crushing and/or sieving in order to attain a desired particle size distribution.

[0035] Suitable shaped catalyst supports include porous carbon products prepared by: mixing a carbonaceous material (e.g., carbon black) and a binder, optionally in a solvent (e.g., water, organic solvent, mixtures thereof, and the like); shaping the mixture into the desired shape; and carbonizing the shaped mixture as described, for example, in WO 2015/168327, which is incorporated herein by reference. In some embodiments, the binder is a resin or other polymer. In other embodiments, the binder is a saccharide. In some embodiments, the mixture comprising a carbonaceous material is shaped by extrusion to produce a shaped catalyst support in the form of an extrudate. The preparation of catalysts of the present invention utilizing a shaped catalyst support in the form of an extrudate is illustrated, for example, in Examples 5, 6, 9, and 12.

[0036] In some embodiments, heterogeneous catalysts of the present invention are prepared with a shaped support (e.g., an extrudate) and further comprise a shell metal layer. As used herein, the term "shell metal layer" refers to a substantially continuous layer comprising one or more metals selected from the group consisting of the first metal (rhodium or iridium), rhenium, mixtures of rhodium and rhenium, and mixtures of iridium and rhenium that is disposed directly adjacent to the outer surface of the support, and which at least partially covers the outer surface of the support. In some embodiments, the shell metal layer penetrates surficial pores of the support, and extends beyond the outer surface of the support to form the shell metal layer. In other embodiments, the shell metal layer extends substantially only inwards into the support. In some embodiments, the shell metal layer consists essentially of the first metal (rhodium or iridium) or consists essentially of rhenium. While in still further embodiments, the shell metal layer comprises or consists essentially of a mixture of rhodium and rhenium or consists essentially of a mixture of iridium and rhenium. In certain embodiments, the shell metal layer may further comprise a promoter metal selected from the group consisting of copper, bismuth, and combinations thereof.

[0037] The shell metal layer or one or more portions thereof may be enriched in content of the one or more metals relative to the concentration of the one or more metals in other regions of the catalyst. In some embodiments the shell metal layer is enriched in rhodium content relative to the concentration of rhodium in regions of the catalyst other than the shell metal layer. In other embodiments, the shell metal layer is enriched in iridium content relative to the concentration of iridium in regions of the catalyst other than the shell metal layer. In still further embodiments, the shell metal layer is enriched in rhenium content relative to the concentration of rhenium in regions of the catalyst other than the shell metal layer.

[0038] The shell metal layer generally has a thickness in the range of from about 10 μm. to about 400 μm. In some embodiments, the thickness of the shell metal layer is in the range of from about 50 μm. to about 150 μm., or from about 50 μm. to about 100 μm.. In certain other embodiments, the thickness of the shell metal layer is in the range of from about 10 μm.. to about 400 μm., 15 μm. to about 300 μm., from about 20 um to about 200 urn, from about 30 μm. to about 100 μm., from about 40 μm. to about 85 um, or from about 50 μm. to about 75 μm.. The preparation of a shaped catalysts using a carbon black extrudate support and having a rhodium- enriched shell metal layer is illustrated, for example, in Example 14.

[0039] Shaped catalyst supports and the resulting catalysts are produced with dimensions suitable for the intended reactor system for catalytic hydrogenolysis of tetrahydrofurfuryl alcohol (THFA) to 1,5-pentanediol as understood by those skilled in the art. For example, extrudate catalyst supports typically used in a fixed bed reactor have a diameter in the range of from about 0.8 mm to about 5 mm, or from about 0.8 mm to about 3 mm. The shaped catalyst supports or the resulting catalysts may optionally be crushed or broken to reduce the average particle size. In some embodiments, the heterogeneous catalyst (and corresponding support) has an average particle size in the range of from about 100 um to about 1000 urn. For example, the heterogeneous catalyst may have an average particle size in the range of from about 100 um to about 1000 um, from about 100 um to about 900 um, from about 100 um to about 800 um, from about 100 um to about 700 um, from about 100 μm to about 600 um, from about 100 um to about 500 um, from about 150 um to about 500 um, from about 150 um to about 450 um, from about 150 um to about 400 um, from about 150 um to about 350 um, or from about 150 um to about 300 um. In some embodiments, the heterogeneous catalyst (and corresponding support) for use in a slurry reactor has an average particle size in the range of from about 25 um to about 800 um, from about 25 um to about 700 um, from about 25 um to about 600 um, from about 50 um to about 500 um, from about 50 um to about 450 um, from about 50 um to about 400 um, from about 50 um to about 350 um, or from about 50 um to about 300 um. It should be noted that the particle size of the final catalyst (i.e., after metal addition) remains essentially the same as the particle size of the support materials. The average particle size can be determined by means known in the art, including laser diffraction particle size analysis. A non-limiting example of a suitable apparatus for determining particle size characteristics is a BECKMAN COULTER LS Particle Size Analyzer (model LS 13 320).

[0040] Non-limiting examples of commercially available carbon black that are suitable for use as catalyst supports in the practice of the present invention (either "as is" in powdered form, or alternatively, when formulated and processed into a shaped form) include Monarch 280 (Cabot Corp.), Monarch 570 (Cabot Corp.), Monarch 700 (Cabot Corp.), and the like.

[0041] Non-limiting examples of commercially available zirconia supports suitable for use as catalyst supports in the practice of the present invention include zirconia extrudate catalyst supports such as XZO 1247 (Saint-Gobain NorPro), SZ 31163 (Saint-Gobain NorPro), SZ 31114 (Saint-Gobain NorPro), SZ 31108 (Saint-Gobain NorPro), and the like.

[0042] Non-limiting examples of commercially available silicon carbide supports suitable for use as catalyst supports in the practice of the present invention include silicon carbide rings available from SICAT Catalyst Inc. (Willstatt, Germany) and the like.

II. Catalyst Preparation

[0043] The catalysts of the present invention can be readily prepared using methods that are well-known to those skilled in the art including, but not limited to, incipient wetness, ion- exchange, deposition-precipitation, vacuum impregnation, and the like. [0044] For example, a catalyst precursor solution may be formed comprising a source of rhenium, rhodium, and/or iridium metal in a suitable solvent such as water to form a precursor solution used to impregnate the support material with the desired metal loading. The rhodium source may be, for example, rhodium nitrate

or rhodium chloride hydrate

The rhenium source may be, for example, perrhenic acid

or ammonium perrhenate The iridium source may be, for example, iridium (III) acetate. Likewise,

precursor solutions may be utilized in the same manner for the addition of optional promoter metal(s). The bismuth source may be, for example, bismuth nitrate (

. The copper source may be, for example, copper nitrate

In one embodiment, the rhodium source is rhodium nitrate and the rhenium source is perrhenic acid. The catalyst precursor solutions may be combined or may be used separately to contact and impregnate the catalyst support material with the rhenium, rhodium, iridium, copper, and/or bismuth metals. That is, the rhenium, rhodium, iridium, copper, and/or bismuth source compounds may be deposited sequentially or simultaneously on the catalyst support.

[0045] Following metal deposition, the impregnated support is typically dried in atmospheric air at a temperature of at least about 50°C, at least about 7S°C, at least about 100°C, at least about 125°C, or at least about 150°C. In certain embodiments, the impregnated catalyst support is dried at about 120°C. The drying time may vary and typically is at least about 10 minutes, at least about IS minutes, at least about 30 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, or at least about S hours. In these and other embodiments, the catalyst may be dried under sub-atmospheric pressure conditions.

[0046] Optionally, the dried catalyst may be calcined at higher temperatures of at least about 200°C, at least about 250°C, at least about 300°C, at least about 350°C, and typically from about 400°C to about 500°C for a period of at least about 10 minutes, at least about 15 minutes, at least about 30 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, or at least about 5 hours.

[0047] The catalyst metals at the surface of the support material are typically reduced in a flow of hydrogen-containing gas (e.g., forming gas 5% H₂, 95% N₂) while maintained at a temperature of least about 200°C, at least about 250°C, at least about 300°C, at least about 350°C, and typically from about 400°C to about 500°C for at least about 10 minutes, at least about 15 minutes, at least about 30 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, or at least about 5 hours. Illustrative catalyst preparation protocols are provided in the Examples. III. Process For Producing 1.5-Pentanediol

[0048] The present invention also provides a process for preparing 1,5-pentanediol, the process comprising: (a) reacting THFA with hydrogen in a reaction mixture in the presence of a heterogeneous catalyst of the present invention to convert at least a portion of the THFA to 1,5- pentanediol.

[0049] The THFA starting material for the catalytic hydrogenolysis to 1,5-pentanediol is readily available, and in addition may be obtained, for example, by the hydrogenation of furfuryl alcohol. Under certain circumstances (e.g., advantageous alternative feedstock cost), it may be more desirable to utilize furfuryl alcohol as a starting material for the production of 1,5- pentanediol. Thus, in some embodiments, prior to carrying out step (a), the process comprises the step of (¾) reacting furfuryl alcohol with hydrogen in the presence of a heterogeneous catalyst under conditions sufficient to produce THFA. In other embodiments, it may be desirable to obtain furfuryl alcohol, for example, from hydrogenation of furfural and use furfural as the starting material for the production of PDO. Thus, in a further embodiment, prior to carrying out step (a), the process comprises the step of (¾) reacting furfural with hydrogen in the presence of a heterogeneous catalyst under conditions sufficient to produce furfuryl alcohol; and the step of (a_i) reacting the furfuryl alcohol with hydrogen in the presence of a heterogeneous catalyst under conditions sufficient to product THFA. Examples of suitable catalysts and conditions for steps (a_i) and/or (aa) can be seen, for example, in Merat, N et al., High Selective Production of Ttetrahydrofurfuryl Alcohol: Catalytic Hydrogenation of Furfural and Furfuryl Alcohol (1990), J. Chem. Technol. Biotechnoi, 48: 145-159 andNakagawa, Y et al., Total Hydrogenation of Furfural over a Silica-Supported Nickel Catalyst Prepared by the Reduction of a Nickel Nitrate Precursor (2012), ChemCatChem, 4: 1791-1797. Significantly, furfural may be isolated from biofeed materials. For example, furfural is commonly recovered from agricultural waste products and crop residues, such as peanut hulls, cottonseed hulls, beet pulp, sugar cane pulp, rice bran, rice chaff, rye, flax, straw, and sawdust. Suitable means for the isolation of furfural from these sources are well known in the art.

[0050] In certain embodiments, it may be desirable to include a solvent in the reaction mixture. Solvents that are suitable for use in the hydrogenolysis reaction mixture include water, an organic solvent such as alcohols, esters, ethers, ketones, organic acids (e.g., acetic acid, propionic acid, butyric acid, and the like), as well as mixtures of any two or more thereof. In certain embodiments, the solvent is selected from the group consisting of water, and mixtures thereof. In some embodiments, the solvent comprises an organic solvent. In other embodiments the solvent comprises or is water. When the solvent is not solely water, it is often a mixture of water and an organic solvent. In certain of the foregoing embodiments, the organic solvent is a water-miscible organic solvent. When the solvent is a water-miscible organic solvent, the solvent may be selected from the group consisting of a water-miscible ether, a water-miscible ketone, a water-miscible organic acid, a water-miscible aldehyde, and a water-miscible ester.

[0051] The catalytic processes of the present invention can be conducted in a batch, semi-batch, or continuous reactor system comprising at least one fixed bed reactor, trickle bed reactor, slurry phase reactor, moving bed reactor, or any other reactor configuration that allows for heterogeneous catalytic reactions and defines a hydrogenolysis reaction zone comprising the catalyst described herein. Examples of such reactors are described in Chemical Process

Equipment-Selection and Design, Couper et al., Elsevier 1990, which is incorporated herein by reference. It should be understood that the THFA (or optionally furfural or ftirfuryl alcohol), hydrogen, optional solvent, and heterogeneous catalyst may be introduced into a suitable reactor separately or in various combinations. One skilled in the art will understand that the manner in which the catalyst is deployed is dependent upon the type of reactor used.

[0052] In various embodiments, the hydrogenolysis of THFA is performed in a reactor system comprising one or more continuous reactors (e.g., fixed bed reactor) defining a hydrogenolysis reaction zone comprising the catalyst described herein. In some embodiments, it may be desirable to carry out step (a) in at least two serially positioned continuous reactors (e.g., fixed bed reactors), where the effluent of the first reactor (i.e., the reactor receiving the THFA feedstock) is the feedstock for the second reactor, and where the effluent from the second reactor is the feedstock for an optional third reactor, and so on. This type of configuration is suitable when it is desired to alter reaction conditions during the course of the process. Typically, at least one reaction condition selected from the group consisting of reaction temperature, hydrogen partial pressure, and solvent composition, differs with respect to each serially positioned fixed bed reactor. In other embodiments, the reaction may alternatively be carried out in one or more of a batch reactor, semi-batch reactor, or slurry reactor.

[0053] Generally, a molar excess of hydrogen with respect to THFA is provided during the reaction step. In certain embodiments, the molar excess of hydrogen is introduced during the hydrogenolysis reaction step. For example, the hydrogen to THFA molar ratio is typically about 1.5:1, 2:1, 4:1, 8: 1 10: 1 or greater, and more preferably in the range of from 1.5:1 to 10: 1 to maximize conversion of THFA. During the hydrogenolysis reaction step, the partial pressure of hydrogen is typically maintained at a pressure in the range of from about 200 psia (1379 kPa) to about 2000 psia (13790 kPa) or from about 600 psia (4137 kPa) to about 1100 psia (7584 kPa).

[0054] The hydrogenolysis reaction is typically carried out at a temperature in the range of from about 50°C to about 500°C, from about 50°C to about 400°C, from about 50°C to about 200°C, from about 50°C to about 150°C, or from about 50°C to about 140"C. In some embodiments, the reaction may be carried out at a temperature in the range of from about 60^' C to about 140°C, from about 60°C to about 130°C, from about 65°C to about 130 C, from about 65°C to about 125"C, from about 70° C to about 125"C, or from about 90°C to about 120°C.

[0055] The quantity of catalyst used for the hydrogenolysis reaction will vary depending on the reactor configuration and the specific reaction conditions employed and can be readily determined by the skilled person.

[0056] In some embodiments, the hydrogenolysis reaction produces a mixture of products. The catalytic hydrogenolysis of THFA results in the ring opening of the cyclic ether through scission of the C-0 ether bond. The processes of the present invention strongly favor formation of 1,5-pentanediol which occurs due to scission of the ether bond between oxygen and the carbon at the 2 position. However, in some embodiments, minor products may be produced at relatively low levels when scission of the ether bond occurs between oxygen and the carbon at the 5 position, followed by hydrodeoxygenation of a terminal hydroxyl group in some cases. These minor products include 1-pentanol, 2-pentanol, 1,2-pentandiol, and 1,4-pentandiol. Thus, in some embodiments, a mixture of products is produced comprising 1,5-pentanediol, and at least a second product selected from the group consisting of 1-pentanol, 2-pentanol, 1,2- pentanediol, and 1,4-pentanediol.

[0057] When minor products are produced, they are produced at very low quantities relative to the quantity of 1,5-pentanediol produced. Thus, in some embodiments, the yield of 1,2-pentanediol is less than about 5%, less man about 4%, less than about 3%, less than about 2%, less than about 1%, less than about 0.5%, or less than about 0.25%. In certain embodiments, the yield of 1,2-pentanediol is in the range of from about 0.1% to about 5%, from about 0.1% to about 4%, from about 0.1% to about 3%, from about 0.1% to about 2%, or from about 0.1% to about 1%. Alternatively, the reaction product can have a molar ratio of 1,5-pentanediol to 1,2- pentanediol that is at least about 5: 1, at least about 10: 1, at least about 25: 1, at least about 50: 1, at least about 75: 1, or at least about 100: 1. In certain embodiments, the molar ratio of 1,5- pentanediol to 1,2-pentanediol may be in the range of from about 5: 1 to about 500: 1, from about 5:1 to about 250:1, or from about 5:1 to about 100:1. In one embodiment, the molar ratio of 1,5- pentanediol to 1,2-pentanediol is in the range of from about 10: 1 to about 500: 1, from about 10: 1 to about 250:1, or from about 10: 1 to about 100:1. In certain other embodiments, the molar ratio of 1,5-pentanediol to 1,2-pentanediol is in the range of from about 25:1 to about 500: 1, from about 25: 1 to about 250: 1, or from about 25: 1 to about 100: 1. In one embodiment, the molar ratio of 1,5-pentanediol to 1,2-pentanediol is in the range of from about 50: 1 to about 500: 1 , from about 50: 1 to about 250: 1 , or from about 50: 1 to about 100: 1. In further

embodiments, the molar ratio of 1,5-pentanediol to 1,2-pentanediol is in the range of from about 75: 1 to about 500: 1, from about 75: 1 to about 250: 1, or from about 75: 1 to about 100: 1. In another embodiment, the molar ratio of 1,5-pentanediol to 1,2-pentanediol is in the range of from about 5: 1 to about 500: 1 , from about 10: 1 to about 500: 1, from about 15: 1 to about 500: 1, from about 20:1 to about 500: 1, from about 25: 1 to about 500:1, from about 50:1 to about 500:1, or from about 75: 1 to about 500: 1.

[0058] The hydrogenolysis of THFA using the catalysts and processes described herein may provide a THFA conversion of at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99%. The yield of 1,5-pentanediol may be as high as at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99%.

[0059] The hydrogenolysis reaction of the present invention typically produces PDO at a productivity level that is at least or greater than about 0.10 g PDO/g catalyst-hour. Often, the reaction produces PDO at level that is at least about 0.15 g PDO/g catalyst-hour, or at least about 0.2 g PDO/g catalyst-hour, or at least about 0.3 g PDO/g, catalyst-hour.

[0060] When the hydrogenolysis reaction step is carried out as a continuous process, in some embodiments, the reaction is carried out for a time on stream (TOS) period of at least 100 hours. In other embodiments in which the hydrogenolysis reaction step is carried out as a continuous process, the reaction is carried out for a TOS period of at least about 150 hours, at least about 200 hours, at least about 250 hours, at least about 300 hours, at least about 350 hours, at least about 400 hours, at least about 450 hours, at least about 500 hours, at least about 550 hours, at least about 600 hours, at least about 650 hours, at least about 700 hours at least about 750 hours at least about 800 hours, at least about 850 hours, at least about 900 hours, at least about 950 hours, or at least about 1000 hours or longer.

[0061] Heterogeneous catalysts of the present invention are highly active, specifically with respect to the hydrogenolysis of THFA to PDO, as demonstrated by the production of PDO at high conversions and high PDO specificities (i.e., high PDO yields). The catalysts are also stable under continuous process conditions. As used herein, the terms "stable" or "stability" when used in the context of describing catalytic performance, refers to the retention of the ability to catalyze the hydrogenolysis of THFA to PDO at not less than about 50% of the initial PDO selectivity under continuous process conditions (as described, for example, in Examples 5, 9, 10, and 13) after a time on stream (TOS) period of at least about 500 hours. In certain embodiments, stability may be further demonstrated by the retention of the ability to catalyze the hydrogenolysis of THFA to PDO at not less than about 50% of the initial THFA conversion under continuous process conditions (as described, for example, in Examples 5, 9, 10, and 13) after a time on stream (TOS) period of at least about 500 hours. The term "initial PDO selectivity" refers herein to PDO selectivity as determined at 100 hours on stream. The term "initial THFA conversion" refers herein to the conversion of THFA as determined at 100 hours on stream.

[0062] In some embodiments, heterogeneous catalysts of the present invention retain the ability to catalyze the hydrogenolysis of THFA to PDO at not less than about 50%, not less than about 60%, not less than about 70%, not less than about 80%, not less than about 85%, or not less than about 90% of initial PDO selectivity and not less than about 50%, not less than about 60%, not less than about 70%, not less than about 80%, not less than about 85%, or not less than about 90% of the initial THFA conversion under continuous process conditions (as described, for example, in Example 10), after a TOS period of about 150 hours, about 200 hours, about 250 hours, about 300 hours, about 350 hours, about 400 hours, about 450 hours, about 500 hours, about 550 hours, about 600 hours, about 650 hours, about 700 hours, about 750 hours, about 800 hours, about 850 hours, about 900 hours, about 950 hours about 1000 hours or longer. In other embodiments, the catalysts may retain the ability to catalyze the hydrogenolysis of THFA to PDO at not less than about 85% of the initial PDO selectivity and not less than about 80% of the initial THFA conversion under continuous process conditions (as described, for example, in Examples 5, 9, 10, and 13) after a time on stream (TOS) period of at least about 100 hours, at least about 150 hours, about 200 hours, about 250 hours, about 300 hours, about 350 hours, about 400 hours, about 450 hours, about 500 hours, about 550 hours, about 600 hours, about 650 hours, about 700 hours, about 750 hours, about 800 hours, about 850 hours, about 900 hours, about 950 hours about 1000 hours or longer.

[0063] In certain embodiments, the solvent can be removed from the resulting mixture of products, for example, by distillation, evaporation, extraction, and the like. Subsequently, 1,5- pentanediol may be purified from the remaining products using techniques known in the industry such as distillation, which may be conducted at atmospheric or sub atmospheric pressures or in certain circumstances higher that atmospheric pressure. After purification of the 1,5-pentanediol, the other reaction components such as 1-pentanol, 1,2-pentanediol, and unreacted THFA can be used as a 1,2-pentanediol product composition, or the composition can be subjected to further process steps, e.g., optional separation and recover}' of unreacted THFA which can be optionally and recycled to the hydrogenation reactor.

IV. Downstream Chemical Products

[0064] 1 ,5-pentanediol formed by the processes described herein may be further used for the preparation of certain other products by means generally known in the art. For example, 1,5- pentanediol may be useful in the preparation of glutaric acid, glutaraldehyde, delta- valerolactone, piperidine, pyridine, polycarbonates, polyethers, polyesters, polyester polyols and polyureathanes therefrom.

[0065] The following non-limiting examples are provided to further illustrate the present invention.

EXAMPLES

Example 1 : Preparation of Rhodium-Rhenium Heterogeneous Catalysts on a Carbon Black (Powder) Support

[0066] Rhodium-rhenium catalysts utilizing four different powdered carbon black support products (Monarch 280, Monarch 570, Monarch 700, and Vulcan XC-72, all products of Cabot Corp.) were prepared. A rhodium nitrate (Rh(NC>3)3) solution obtained from Heraeus Deutschland (152.7 mg Rh/ml) and a perrhenic acid (HC^Re) solution obtained from Sigma Aldrich (1170 mg Re/ml ) were diluted with the amount of deionized water indicated in Table 1, below. The diluted solution was then used to impregnate 0.2 g of the catalyst support, in order to prepare a catalyst containing 4 wt.% Rh and 4 wt.% Re. The impregnation step was carried out using the quantities/volumes of support and solutions set forth in Table 1. After impregnation of the catalyst support, the materials were dried for three hours in atmospheric air at a temperature of 120°C. The dried catalyst supports were then calcined in atmospheric air at a temperature of 350°C for three hours (heating at a ramp rate of 5°C/min). Finally, the catalysts metals were reduced in forming gas at a temperature of 350°C for three hours (heating at a

ramp rate of 5°C/min).

Table 1: Formulation for Catalyst Preparation

[0067] The resulting catalysts were tested to determine the BET specific surface area using the method described in S. Brunauer, P.H. Emmett, E. Teller, J. Am. Chem. Soc. 1938, 60, 309-331, and ASTM D3663-03(2008) Standard Test Method for Surface Area of Catalysts and Catalyst Carriers, both of which are incorporated herein by reference. Average pore diameters were determined in accordance with the BJH method described in E.P. Barrett, L.G. Joyner, P. P. Halenda, J. Am Chem. Soc. 1951, 73, 373-380, and ASTM D4222-03(2008) Standard Test Method for Determination of Nitrogen Adsorption and Desorption Isotherms of Catalysts and Catalyst Carriers by Static Volumetric Measurements. The metal loading of each catalyst (i.e., Rh wt.% and Re wt.% on the basis of total catalyst weight) was determined by mass balance. The catalyst properties are provided in Table 2.

Table 2: Catalyst Properties

The catalytic activities for these catalysts were determined as described in Example 2.

Example 2: Characterization of the Catalytic Activity of Catalysts of Example 1

[0068] Catalysts of Example 1 were tested in the following manner. 20 mg of the catalyst was weighed into a glass vial followed by the addition of 0.2 ml of 0.8M THFA (in water) solution. The glass vials were loaded into a 96-well insert, situated in a high pressure high throughput reactor ("HiP-pressure reactor", see Diamond, G. M, Murphy, V., Boussie, T.R., in Modern Applications of High Throughput R&D in Heterogeneous Catalysis, eds., Hagemeyer, A. and Volpe, A. Jr., Bentham Science Publishers 2014, Chapter 8, 299-309; U.S. Pat. No. 8,669,397) and the reactor was closed. The reactor was heated to the reaction temperature of 120°C and was maintained at that temperature for 2 hours with a hydrogen pressure of 600 psia, while the reactor was shaken. After 2 hours, the shaking was stopped and reactor was cooled, followed by slowly releasing the pressure in the reactor. The reaction solutions were diluted and analyzed by gas chromatography (GC) to determine the quantity of PDO produced. Molar selecti vines, molar yields, and catalyst productivities were calculated and the results are presented in Table 3.

Table 3: Catalytic Performance

[0069] Catalysts having a BET specific surface area of from about 100 m²/g to about 180 m²/g and an average pore diameter of about 11 to about 23 nm exhibited the best performance. A graph of the 1,5-pentanediol yield compared to the BET specific surface area of the catalysts is provided in Figure 1. These results suggest that optimal yield may be achieved at a BET specific surface area of about 100 m²/g. Example 3: Preparation and Characterization of 3 wt.% Rh. 3.5 wt.% Re Heterogeneous Catalysts on a Carbon Black (Powder) Support

[0070] A further experiment was performed to investigate the impact of lower metal loadings of rhodium and rhenium on catalytic performance. Two different powdered carbon black support products were used, Monarch 570 and XC-72 (both available from Cabot Corp.). The catalysts were prepared using the procedures set forth in Example 1, with the exception that sufficient rhodium nitrate and perrhenic acid was used to achieve the desired metal loading of 3 wt.% rhodium and 3.5 wt.% rhenium relative to the total weight of the catalyst.

[0071] The BET specific surface area and average pore diameter of the catalysts was determined as described in Example 1. Catalytic performance was evaluated using the method described in Example 2 with the following alterations. A vial for each catalyst was prepared containing 15 mg of the catalyst and 0.2 ml of a 0.4M THFA (water) solution. Vials were placed in a HiP-pressure reactor and hydrogenolysis was performed at 100°C with a hydrogen pressure of 600 psia for a period of 2 hours. Molar selectivities, molar yields, and catalyst productivities are presented in Table 4.

Table 4: Characterization of Heterogeneous Catalyst (3 wt.% Rh + 3.5 wt.% Re/Carbon

(powder))

[0072] The results suggest mat a catalyst with a BET specific surface area of about 100 m²/g and an average pore diameter of about 23 nm may provide improved performance even at lower metal loadings. Example 4: Preparation and Characterization of Heterogeneous Catalysts with 4 wt.%

Rhodium and Varying Rhenium Loadings on Carbon (Powder) Supports

[0073] A further experiment was performed for carbon supported catalysts, in order to evaluate the impact of differing weight ratios of rhodium and rhenium

[0074] Three catalysts were prepared using the procedure generally described in

Example 1. Catalyst support type and quantity, as well as the rhodium loading were held constant between all three catalysts, while the rhenium loading was varied. The properties of these catalysts are summarized in Table 5.

Table 5: Catalyst Properties

[0075] Catalytic performance was assessed in accordance with the method described in Example 2. PDO molar selectivity, PDO molar yield, and catalyst productivity for each catalyst is provided in Table 6.

Table 6. Catalytic Performance

[0076] These results suggest that the best catalyst performance can be achieved where the Re/Rh weight ratio is near 1:1. Catalysts with a Re/Rh weight ratio of 0.5 : 1 and 1.5: 1 resulted in slightly lower overall performance; in particular a lower yield of 1,5-pentanediol. Example 5: Preparation and Testing of a 3.5 wt% Rh. 4.5 wt% Re Heterogenous Catalyst on a Carbon Black (Extrudate)-Support in a Continuous Flow Fixed Bed Reactor

[0077] A rhodium-rhenium catalyst containing 3.5 wt.% Rh and 4.5 wt.% Re was prepared on a cylindrical carbon black extrudate with a 0.85 mm diameter, 1-5 mm length, a surface area of 142 m²/g, and an average pore diameter of 12 nm The cylindrical carbon black extrudate was prepared using methods described in WO 2015/168327, which is incorporated herein by reference. The catalyst was prepared in the following manner. A solution was first prepared containing 0.872 ml of a rhodium nitrate solution (supplied by Heraeus containing 152.7 mg Rh/ml), 0.146 ml of a perrhenic acid solution (supplied by Aldrich containing 1170 mg Re/ml) and 1.607 ml deionized water. The resulting solution was used to impregnate 3.5 g of carbon black extrudate material. After the impregnation, the material was left to equilibrate for 2 hours at room temperature and was then dried for 2 hours at 120°C. The resulting dried material was then subjected to a reduction in forming gas (5% ¾, 95% N₂) at a temperature of 350°C for 3 hours.

[0078] Following reduction, 3 g of the catalyst was charged in a continuous flow stainless steel fixed bed reactor (6.4 mm OD x 38 cm long). The catalyst was charged by vibration packing the catalyst in the reactor along with glass beads (1 mm) and silicon carbide particles (180 μm ) such that a height of approximately 5 cm of glass beads was located above the catalyst bed and a height of approximately 5 cm of silicon carbide particles was located below the catalyst bed. The packed reactor tube was clamped in an aluminum block heater equipped with a PID controller. The reactor was operated with a co-current down flow of the liquid and hydrogen gas. Gas and liquid flows were regulated by a mass flow controller and HPLC pump respectively. For a period of 900 hours a reaction mixture of 0.4M THFA at a temperature of 70°C was passed through the reactor at a flow rate of 12 ml/hour. A hydrogen pressure of 1000 psia was maintained for the duration of the experiment. A 1,5-pentanediol yield of 70-75% was achieved for the duration of the 900 hour run, illustrating the high selectivity and stability of the carbon black extrudate catalyst. Additionally, the catalyst productivity was greater than 0.10 g 1,5-pentanediol/ [g catalyst-hour] for the duration of the run. Molar PDO selectivity and molar PDO yield are depicted as a function of time (hours) in Figure 2. The results indicate that good catalytic performance was achieved over the duration of the run. The by-products recorded during this run were found to be 1-pentanol (2-3% yield) and 2-pentanol (1% yield). Reactor product stream samples were collected approximately every 4 hours for the duration of the run. Samples were then combined or pooled in the following manner: Pooled Sample 1: Pooled from samples 1 - 24 (collected from the time of 4 -100 hours on stream)

Pooled Sample 2: Pooled from samples 25 - 48 (collected from the time of 104 - 192 hours on stream)

Pooled Sample 3: Pooled from samples 49 - 72 (collected from the time of 196 - 288 hours on stream)

Pooled Sample 4: Pooled from samples 73 - 96 (collected from the time of 292 - 384 hours on stream)

Pooled Sample 5: Pooled from samples 97 - 120 (collected from the time of 388 - 480 hours on stream)

Pooled Sample 6: Pooled from samples 121 - 156 (collected from the time of 484 - 624 hours on stream)

Pooled Sample 7: Pooled from samples 157 - 180 (collected from the time of 628 -720 hours on stream)

Pooled Sample 8: Pooled from samples 181 - 204 (collected from the time of 724 - 816 hours on stream)

Pooled Sample 9: Pooled from samples 205 - 228 (collected from the time of 820 - 912 hours on stream)

[0079] Each of the pooled product stream samples was analyzed for the presence of rhodium and rhenium using ICP-OES (inductively coupled plasma optical emission spectroscopy). The ICP spectroscopy analysis did not reveal the presence of rhodium and rhenium in any of the pooled product stream samples, indicating that the catalyst was not leaching rhodium or rhenium for the duration of this 900 hour run.

Example 6: Preparation and Characterization of Heterogeneous Zirconia (Extrudate)- Supported Catalysts with Varying Rhodium and Rhenium Loadings

[0080] Zirconia extrudate supported catalysts were prepared as follows. A zirconia extrudate catalyst support, 1.5 mm diameter XZO 1247 (Saint-Gobain NorPro), having a BET specific surface area of 45 m²/g and an average pore diameter of about 30 nm was crushed and sieved to prepare a zirconia support having a particle size of from about 150 pm to about 425 um. A rhodium nitrate (Rh(NC>3)3) solution (152.7 mg Rh/ml) and perrhenic acid (HC^Re) solution (322 mg Re/ml) were diluted with deionized water. These solutions were then used to impregnate 0.2 g of catalyst support. The volume of rhodium nitrate and perrhenic acid used to prepare the catalysts is set forth in Table 7 as Rh sol. and Re sol. respectively. After impregnation of the catalyst support, the materials were dried for two hours at a temperature of 120°C. The dried catalyst supports were then calcined in 350°C air for three hours (with a temperature ramp rate of 5°C/min). Finally, the catalysts metals were reduced in forming gas N₂) at a temperature of 350°C for 3 hours (with a temperature ramp rate of

Table 7: Formulations for the Preparation of Zirconia Catalysts

[0081] The metal loading for each catalyst sample was determined by mass balance. The BET specific surface area was measured as described in Example 1. The properties of the resulting catalysts are shown below in Table 8.

Table 8: Catalyst Physical Properties

Example 7; Characterization of Catalytic Activity of the Catalysts of Example 6

[0082] Catalysts of Example 6 were tested using the method of Example 2 with the following alterations. A vial for each catalyst was prepared containing 30 mg of the catalyst and 0.2 ml of a 0.4M THFA (in water) solution. Vials were placed in a HiP-pressure reactor and the reaction was performed at 100°C with a hydrogen pressure of 800 psia, for a period of 2 hours.

[0083] The weight ratio of rhenium to rhodium, the molar selectivity of conversion of THFA to 1,5-pentanediol, and the overall molar 1,5-pentanediol yield are provided below in Table 9.

Table 9: Catalytic Performance

[0084] The results of this experiment demonstrate that a Re/Rh ratio of at least about 1:1 results in improved catalytic activity for these zirconia-supported catalysts. The catalyst with a Re/Rh weight ratio of about 1.33:1 (4:3) performed the best.

Example 8: Catalytic Activity of Heterogeneous Zirconia fExtrudateVSupported Catalyst at Various Metal Loadings

[0085] Catalysts of Example 6 were again screened using the method of Example 2 with the following alterations. A vial for each catalyst was prepared containing 15 mg of the catalyst and 0.2 ml of a 0.8M THFA (water) solution. Vials were placed in a HiP-pressure reactor and the reaction was performed at 100°C with a hydrogen pressure of 600 psia, for a period of 2 hours.

[0086] The weight ratio of rhenium to rhodium, the molar selectivity of conversion of THFA to 1,5-pentanediol, and the overall molar 1,5-pentanediol yield are provided below in Table 10. Table 10: Catalytic Performance

[0087] These results show that, even with an increase in THFA concentration and decrease in hydrogen pressure, a Re/Rh weight ratio of 0.25 : 1 still provided no detectable 1,5- pentanediol selectivity or yield. Under these process conditions, even a Re/Rh ratio of 0.5:1 provided no detectable selectivity or yield. However, similar to the results obtained in the experiment of Example 7, a Re/Rh weight ratio in the range of from about 1 : 1 to about 1.5:1 appears to provide good PDO yield and selectivity. The catalyst with a Re/Rh weight ratio of about 1.33:1 (4:3) performed the best.

Example 9: Preparation. Characterization, and Testing of a Heterogeneous Zirconia (Extrudate)-Supported Catalyst in a Continuous Flow Fixed Bed Process

[0088] A 3 wt% Rh, 3.5 wt% Re catalyst on a 1.5 mm diameter zirconia extrudate support (XZO 1247, St. Gobain NorPro) was prepared in accordance with the method of Example 6, with the exception that the extrudate was not crushed or sieved prior to impregnation with the metal solutions. The BET specific surface area of the catalyst was determined as described in Example 1. The catalyst properties are summarized in Table 11.

Table 11 : Catalyst Properties

[0089] A continuous flow fixed bed hydrogenolysis reaction was performed using the 1.5 mm diameter zirconia(extrudate)-supported catalyst over an extended period of time (1000 hours) as follows. 5 g of the catalyst was charged in a continuous flow stainless steel fixed bed reactor (6.4 mm OD x 38 cm long). The catalyst was charged by vibration packing the catalyst in the reactor along with glass beads (1 mm) and silicon carbide particles (180 μπτ) such that a height of approximately 5 cm of glass beads was located above the catalyst bed and a height of approximately 5 cm of silicon carbide particles was located below the catalyst bed. The packed reactor tube was clamped in an aluminum block heater equipped with a PID controller. The reactor was operated with a co-current downflow of the liquid and hydrogen gas. Gas and liquid flows were regulated by a mass flow controller and HPLC pump respectively. For a period of 1000 hours, a 0.4M THFA (in water) solution was passed through the reactor at a flow rate of 12 ml/h and temperature of 90°C. Hydrogen was introduced into the reactor and the reactor was maintained at a pressure of 1000 psia for the duration of the experiment. The desired reaction mixture flow rate and temperature were achieved after approximately 90 hours time on stream. A plot of PDO molar selectivity and molar yield as a function of time is provided in Figure 3. Additionally, the reactor product was collected for the duration of the run and analyzed by ICP- OES at the end of the run for the presence of rhodium and rhenium 1CP spectroscopy did not detect the presence of rhodium, and the presence of rhenium was detected at a level of 600 parts per billion. These ICP results indicate that no detectable rhodium leached and a very low level of rhenium leached from the catalyst during the 1000 hour duration of this run.

[0090] The following by-products were recorded during this run: 1-pentanol (4-5% yield), 1,2-pentanediol (1% yield) and 1,4-pentanediol (1 %). The results demonstrate that the disclosed zirconia supported rhodium-rhenium catalyst achieves high molar selectivity and molar yield for the hydrogenolysis of THFA to 1,5-pentanediol. Additionally, retention of high 1,5-pentanediol selectivity is achieved over an extended period of time (1000 hours). While a slight decrease in 1,5-pentanediol yield occurred over the course of the experiment, a PDO yield of approximately 70% after 1000 hours of continuous catalyst use was achieved, demonstrating the stability of the catalyst and process.

Example 10: Preparation and Characterization of the Catalytic Activity of

Rhodium/Rhenium Catalysts on Carbon (Crushed Extrudate) and Silicon Carbide (Crushed Rings) Supports

[0091] A series of rhodium-rhenium catalysts were prepared using carbon black extrudates (prepared according to WO 2015/168327, BET specific surface area 121 m²/g) and silicon carbide rings (available from S1CAT Catalysts Inc., BET specific surface area 30 m²/g) as support materials. Prior to catalyst preparation, both support materials were first crushed and the 150 um to 425 um fraction was sieved out. Two sets of catalysts were then prepared with each support material: 3wt.% Rh + 4wt.% Re catalysts and 4wt.% Rh + 5wt.% Re catalysts. [0092] The catalysts were prepared as follows. For catalysts with 3wt.% Rh and 4 wt.% Re, 0.0423 ml of a Rh(N0₃)3 solution obtained from Heraeus Deutschland (152.7 mg Rh/ ml) and 0.0074 ml of a Perrhenic acid (H0₄Re) solution obtained from Sigma Aldrich (1170 mg Re/ml) were used. For catalysts with 4 wt.% Rh and 5 wt.% Re, 0.0576 ml of a Rh(N0₃)3 solution obtained from Heraeus Deutschland (152.7 mg Rh/ ml) and 0.0094 ml of a Perrhenic acid (H0₄Re) solution obtained from Sigma Aldrich (1170 mg Re/ml) were used. These solutions were diluted with deionized water to reach a total volume of 0.180 ml for carbon support impregnation and 0.140 ml for silicon carbide support impregnation. Subsequently, 0.2 g of each support material was impregnated with the diluted solutions. The impregnated support materials were dried at 120°C for 2 hours under nitrogen flow and reduced with forming gas (5% H₂ in N₂) at a temperature of 350°C for 3 hours (with a temperature ramp of 5°C/min).

[0093] Catalyst activity was tested in a HiP-pressure reactor as follows. Reaction vials were charged with 5, 10, and 15 mg of catalyst and 0.2 ml of 0.4M THFA in water. The reaction was performed at a temperature 100°C for 3 hours, with a hydrogen pressure of 600 psia. The results are presented in Tables 12 and 13, which depict PDO molar selectivity and PDO molar yield as a function of catalyst amount for each support material. Table 12 reports these values for the catalysts prepared using a crushed carbon extrudate support while Table 13 reports values for the catalysts prepared using crushed rings of silicon carbide as the support material.

Table 12: Catalytic Performance for Rh + Re/Carbon (crushed extrudates) Catalysts

Table 13: Catalytic Performance for Rh + Re/Silicon Carbide (crushed rings) Catalysts

[0094] As can be seen from these results, silicon carbide-supported catalysts were highly selective for PDO and resulted in greater PDO molar yield, as compared to the carbon-supported catalyst with the same metal loadings.

Example 11: Rhodium/Rhenium and lridium/Rhenium Catalysts on Carbon Black

(Powder) and Silicon Carbide (Crushed Rings) Supports Promoted by Bismuth and Cooper.

[0095] A series of rhodium-rhenium and iridium-rhenium catalysts were prepared on carbon black powder (Ensaco 250G, commercially available from Imerys Graphite and Carbon (formerly TIMCAL) and having a BET specific surface area of 64 m²/g) and silicon carbide powder (prepared by crushing silicon carbide rings available from SIC AT to a size of 150 μm.- 250 μm. and having a BET specific surface area of 30 m²/g) supports. Bismuth and copper promoter metals were added to these catalyst at different (wt.%) levels. The catalysts were prepared using the following solutions: Rh(N03)3 (152.7 mg Rh/ml supplied by Heraeus)); Perrhenic acid (322 mg Re/ml, prepared by diluting a perrhenic acid solution supplied by Aldrich); Iridium (III) acetate (41 mg Ir/ml, prepared from iridium (ΙII) acetate supplied by Heraeus); BiN0₃ (400 mg Bi/ml, prepared from BiN0₃●5H₂0 supplied by Aldrich); Cu(N0₃)₂ (92 mg Cu/ml, prepared from Cu(N03)₂ ·3Η₂0 supplied by Aldrich). Combined solutions were diluted with deionized water as shown below in Table 14 and used to impregnate 0.1 g of the support. The impregnated support materials were dried at 120 C for 2 hours under nitrogen flow and reduced with forming gas (5% H₂ in N₂) at a temperature of 350°C for 3 hours (with a temperature ramp of 5°C/min). Table 14 illustrates the recipes used to prepare a range of rhodium-rhenium and iridium-rhenium catalysts promoted by bismuth or copper.

[0096] The catalysts prepared in Table 14 were tested for catalyst activity using a HiP- pressure reactor as follows. Reaction vials were charged with 20 mg of catalyst and 0.2 ml of 0.4M THFA in water. The reaction was performed at a temperature 90 C for 2 hours. The hydrogen pressure was maintained at 800 psia for the catalysts formulated on carbon and 600 psia for the catalysts formulated on silicon carbide. The results are presented in Table 15, 16, and 17, which depict PDO molar selectivity and PDO molar yield.

Table 15: Effect of Bismuth Promotion on Ir/Re Carbon Catalysts

Table 16: Effect of Copper Promotion on Ir/Re Carbon Catalysts

Table 17: Effect of Copper and Bismuth Promotion on Rh-Re Silicon Carbide Catalysts

Example 12: Preparation of a Rh-Re-Bi Catalyst on a Support of Silicon Carbide Rings

[0097] Silicon carbide rings (5 mm OD and 3 mm ID rings, supplied by SICAT having a BET specific surface area 30 m²/g) were impregnated using the following procedure. 4.065 ml of a Rh(NO₃)3 solution (152.7 mg Rh/ml, supplied by Heraeus), 0.480 ml of a Perrhenic acid solution (1170 mg, Re/ml supplied by Aldrich), and 0.063 ml of a B1NO₃ solution (400 mg Bi/ml prepared from BiN0₃ ^»5H₂0 supplied by Aldrich) were mixed with 3.852 ml of deionized water. The combined solution was added to 17 g of the silicon carbide rings. The resultant impregnated material was exposed to ambient conditions for 2 hours, after which time the materials were dried for 2 hours in atmospheric air at 120°C and then reduced in forming gas (5% H₂, 95% N₂) at a temperature of 350°C for 3 hours (heating at a ramp rate of 5°C/min). The resulting catalyst comprised 3.5 wt.% rhodium, 3.166 wt.% rhenium, and 0.14 wt.% bismuth on the silicon carbide ring support.

Example 13: Catalytic Properties of a Heterogeneous Silicon Carbide-Supported Catalyst in a Continuous Flow Fixed Bed Process

[0098] A fixed bed hydrogenolysis reaction was performed using the silicon carbide supported catalyst of Example 12 over an extended period of time (700 hours) as follows. 16 g of the catalyst was charged in a continuous flow stainless steel fixed bed reactor (6.4 mm OD x 38 cm long). The catalyst was charged by vibration packing the catalyst in the reactor along with glass beads (1 mm) and silicon carbide particles (180 μm.) such that a height of approximately 5 cm of glass beads was located above the catalyst bed and a height of approximately 5 cm of silicon carbide particles was located below the catalyst bed. The packed reactor tube was clamped in an aluminum block heater equipped with a PID controller. The reactor was operated with a co-current downflow of the liquid and hydrogen gas. Gas and liquid flows were regulated by a mass flow controller and HPLC pump respectively. For a period of 700 hours, a 0.4M THFA (in water) solution was passed through the reactor at a flow rate of 30 ml/h (during hours 20-266 of the run) and 15 ml/h (during hours 0-20 and 266 onwards) at a temperature of 70° C. Hydrogen was introduced into the reactor and maintained at a pressure of 1000 psia for the duration of the experiment. A plot of PDO molar selectivity and molar yield as a function of time is provided in Figure 4. The only recorded by-product was 1-pentanol (3-4% yield).

Additionally, reactor product stream samples were collected approximately every 4 hours for the duration of the run. Samples were then combined or pooled in the following manner:

Pooled Sample 1: Pooled from samples collected from 0-48 hours on stream

Pooled Sample 2: Pooled from samples collected from 48-88 hours on stream

Pooled Sample 3: Pooled from samples collected from 88-190 hours on stream

Pooled Sample 4: Pooled from samples collected from 190-288 hours on stream

Pooled Sample 5: Pooled from samples collected from 288-384 hours on stream

Pooled Sample 6: Pooled from samples collected from 384-485 hours on stream

Pooled Sample 7: Pooled from samples collected from 485-535 hours on stream

[0099] Each of the pooled product stream samples was analyzed for the presence of rhodium, rhenium, and bismuth using ICP-OES. The ICP spectroscopy analysis did not reveal the presence of rhodium, rhenium, or bismuth in any of the pooled product stream samples, indicating that the catalyst was not leaching rhodium, rhenium, or bismuth for the duration of this run.

Example 14. Preparation of a 3.5 wt.% Rh/4.5 wt.% Re Carbon Black (Extrudate) Supported Catalyst with a Rhodium Shell

[0100] A catalyst was prepared wherein a shell metal layer enriched in rhodium was disposed at the outer surface of a carbon extrudate support material. To prepare the catalyst, 0.238 ml of rhodium nitrate (152.7 mg Rh/ml supplied by Heraeus) was mixed with 0.262 ml de-ionized H₂0 and then added to 1 g of a carbon black extrudate (prepared according to WO 2015/168327, 1.5 mm diameter x 1-5 mm length, having a BET specific surface area of 122 m²/g). The resultant extrudate material was exposed to ambient conditions for 1 hour, after which time the material was immersed in a 10% ammonium formate solution for 1 hour at 90°C. Following this procedure, the resultant extrudate material was washed with de-ionized water and dried at 120°C for 2 hours under a nitrogen flow. The dried extrudate material was then impregnated with a solution prepared by mixing 0.042 ml of perrhenic acid (1170 mg Re/ml supplied by Aldrich) with 0.458 ml H₂0. The resultant extrudate material was then exposed to ambient conditions for 1 hour, dried at 120°C for 2 hours under a nitrogen flow, and

subsequently reduced under a flow of forming gas (5% H₂ in nitrogen) at 350°C for 3 hours (heated with a 5°C/min ramp rate).

[0101] Figure 5 depicts a micrograph of a cross section of the 3.5 wt% Rh/4.5wt.% Re extrudate catalyst. This micrograph clearly indicates the presence of a 50-75 μηι metal shell around the edge of the extrudate. The numbers 1-8 represent points on the extrudate where an x- ray spectroscopy (EDS) scan was performed to provide quantitative analysis for rhodium across the cross section of the extrudate. Table 18 depicts the results from the EDS analysis and clearly shows that rhodium is more concentrated in the 50-75 μηι shell around the edge of the extrudate. The results also confirm the rhenium is distributed more uniformly across the extrudate.

Table 18: Positional EDS Analysis

Example 15: Comparison of the Catalyst of Example 14 to a Reference Catalyst

[0102] For comparison with the rhodium shell, carbon black extrudate catalyst of Example 14, a reference catalyst (3.5 wt.% Rh/4.5 wt.% Re carbon black extrudate catalyst) was prepared as follows. Using 1 g of the same carbon black support from Example 14, the support was impregnated with a solution containing 0.238 ml Rh(NC>3)3 (152.7 mg Rh/ml, supplied by Heraeus), 0.042 ml of perrhenic acid (1170 mg Re/ml, supplied by Aldrich), and 0.196 ml of de- ionized water. The resultant extrudate material was men exposed to ambient conditions for a period of 1 hour followed by drying at 120°C under a nitrogen flow for 2 hours. Finally, the dried extrudate material was reduced under a flow of forming gas (5% H₂ in nitrogen) at 350°C for 3 hours (heated with a 5°C/min ramp rate).

[0103] The rhodium shell catalyst and the reference catalyst were tested for catalyst activity using a HiP-pressure reactor as follows. Reaction vials were charged with 17 mg of catalyst extrudate and 0.2 ml of 0.4M THFA in water. The reaction was performed at a temperature of 100°C for 2 hours using a hydrogen pressure of 600 psia The results presented in Table 19 illustrate higher selectivity and yield for the rhodium shell catalyst.

Table 19: PDO Selectivity and Yield of Catalysts of Examples 14 and 15

[0104] The results illustrate a method for preparing a rhodium-enriched shell extrudate catalyst. Modifications to the method of preparing the catalyst can be made to adjust the shell thickness and the Re/Rh ratio across the extrudate.

[0105] When introducing elements of the present invention or the preferred

embodiments) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0106] Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A process for preparing 1,5-pentanediol (PDO), the process comprising reacting tetrahydrofurfuryl alcohol (THFA) with hydrogen in a reaction mixture in the presence of a heterogeneous catalyst to convert at least a portion of the tetrahydrofurfuryl alcohol to 1,5- pentanediol, wherein the catalyst comprises a first metal and rhenium on a catalyst support, the first metal is selected from the group consisting of rhodium and iridium and the catalyst support comprises a support material selected from the group consisting of zirconia, silicon carbide, and a carbonaceous material, and wherein when the catalyst support comprises a carbonaceous material, the catalyst has a BET specific surface area in the range of from about 50 m²/g to about 200 m²/g.

2. A catalyst comprising a first metal and rhenium on a catalyst support, wherein the first metal is selected from the group consisting of rhodium and iridium and the catalyst support comprises a support material selected from the group consisting of zirconia, silicon carbide, and a carbonaceous material, and wherein when the catalyst support comprises a carbonaceous material, the catalyst has a BET specific surface area in the range of from about 50 m²/g to about 200 m²/g.

3. The process or catalyst of claim 1 or 2, wherein the support material comprises a carbonaceous material.

4. The process or catalyst of claim 3, wherein the support material comprises carbon black.

5. The process or catalyst of claim 3 or 4, wherein the BET specific surface area is in the range of from about 75 m²/g to about 200 m²/g, from 75 m²/g to about 180 m²/g, from about 75 m²/g to about 150 m²/g, from about 75 m²/g to about 125 m²/g, from about 85 m²/g to about 200 m²/g, from about 85 m²/g to about 150 m²/g, or from about 85 m²/g to about 125 m²/g.

6. The process or catalyst of any one of claims 3 to 5, wherein the heterogeneous catalyst has an average pore diameter in the range of from about 10 nm to about 50 nm or from about 10 nm to about 25 nm.

7. The process or catalyst of claim 1 or 2, wherein the support material comprises zirconia.

8. The process or catalyst of claim 7, wherein the heterogeneous catalyst has a BET specific surface area in the range of from about 10 m²/g to about 200 m²/g, from about 15 m²/g to about 175 m²/g, or from about 15 m²/g to about 150 m²/g, from about 20 m²/g to about 125 m²/g, from about 25 m²/g to about 100 m²/g, from about 30 m²/g to about 75 m²/g, from about 35 m²/g to about 75 m²/g, from about 40 m²/g to about 70 m²/g, or from about 45 m²/g to about 50 m²/g.

9. The process or catalyst of claims 7 or 8, wherein the heterogeneous catalyst has an average pore diameter in the range of from about 10 nm to about 50 nm, from about 15 nm to about 50 nm, from about 20 nm to about 45 nm, from about 20 nm to about 40 nm, or from about 25 nm to about 35 nm

10. The process or catalyst of claim 1 or 2, wherein the support material comprises silicon carbide.

11. The process or catalyst of claim 10, wherein the heterogeneous catalyst has a BET specific surface area in the range of from about 5 m²/g to about 100 m²/g, from about 10 m²/g to about 90 m²/g, from about 10 m²/g to about 80 m²/g, from about 15 m²/g to about 70 m²/g, from about 15 m²/g to about 60 m²/g, from about 20 m²/g to about 50 m²/g, or from about 20 m²/g to about 40 m²/g.

12. The process or catalyst of claims 10 or 11, wherein the heterogeneous catalyst has an average pore diameter in the range of from about 5 nm to about 150 nm, from about 10 nm to about 150 nm, from about 15 nm to about 150 nm, from about 20 nm to about 150 nm, from about 25 nm to about 150 nm, from about 30 nm to about 150 nm, from about 35 nm to about 150 nm, from about 40 nm to about 150 nm, from about 45 nm to about 150 nm, or from about 50 nm to about 150 nm

13. The process or catalyst of any one of claims 1 to 12, wherein rhenium constitutes from about 0.25 wt.% to about 6 wt.%, from about 0.5 wt.% to about 6 wt.%, from about 1 wt.% to about 6 wt.%, from about 2 wt.% to about 6 wt.%, from about 3 wt.% to about 6 wt.%, from about 3 wt.% to about 5 wt.%, or from about 4 wt.% to about 5 wt.% of the total weight of the catalyst.

14. The process or catalyst of any one of claims 1 to 13, wherein the first metal is rhodium and the rhodium constitutes from about 0.25 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, from about 3 wt.% to about 5 wt.%, or from about 4 wt.% to about 5 wt.% of the total weight of the catalyst.

15. The process or catalyst of any one of claims 1 to 14, wherein the weight ratio of rhenium to rhodium present in the catalyst is in the range of from about 0.5: 1 to about 5:1, from about 0.6:1 to about 4:1, from about 0.7:1 to about 3:1, from about 0.8:1, to about 2:1, from about 0.9:1 to about 2:1, from about 1.1:1 to about 2:1, from about 1.1:1 to about 1.8:1, from about 1.1:1 to about 1.7:1, from about 1.2:1 to about 1.6:1, or from about 1.3:1 to about 1.5:1.

16. The process or catalyst of any one of claims 1 to 13, wherein the first metal is iridium and the iridium constitutes from about 0.25 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, or from about 2 wt.% to about 4 wt.% of the total weight of the catalyst.

17. The process or catalyst of any one of claims 1 to 13 or 16, wherein the weight ratio of rhenium to iridium present in the catalyst is in the range of from about 0.5: 1 to about 5:1, from about 0.6: 1 to about 4: 1, from about 0.7: 1 to about 3:1, from about 0.8: 1, to about 2: 1, or from about 0.9:1 to about 2:1.

18. The process or catalyst of any one of claims 1 to 17, wherein the catalyst further comprises a promoter metal selected from the group consisting of copper, bismuth, and combinations thereof.

19. The process or catalyst of claim 18, wherein the promoter metal constitutes from about 0.005 wt.% to about 2 wt.%, from about 0.01 wt.% to about 1 wt.%, from about 0.01 wt.% to about 0.75 wt.%, or from about 0.05 wt.% to about 0.75 wt.% of the total weight of the catalyst.

20. The process or catalyst of any claims 1 to 19, wherein the heterogeneous catalyst is in powder form.

21. The process or catalyst of any one of claims 1 to 21, wherein the heterogeneous catalyst has an average particle size in the range of from about 100 um to about 1000 um, from about 100 um to about 900 um, from about 100 um to about 800 um, from about 100 umto about 700 um, from about 100 um to about 600 um, from about 100 um to about 500 um, from about 150 um to about 500 um, from about 150 um to about 450 um, from about 150 um to about 400 um, from about 150 um to about 350 um, or from about 150 um to about 300 um.

22. The process or catalyst of any one of claims 1 to 21, wherein the heterogeneous catalyst comprises a shaped support.

23. The process or catalyst of claim 22, wherein the shaped support is an extrudate.

24. The process or catalyst of claim 22 or 23, wherein the shaped support has a diameter in the range of from about 1 mm to about 5 mm.

25. The process or catalyst of any one of claims 22 to 24, wherein the heterogeneous catalyst comprises a shell metal layer disposed directly adjacent to and at least partially covering the outer surface of the shaped catalyst support and comprising one or more metals selected from the group consisting of rhodium, iridium, rhenium, mixtures of rhodium and rhenium, and mixtures of iridium and rhenium

26. The process or catalyst of claim 25, wherein the shell metal layer has a thickness in the range of from about 10 um to about 400 um, from about 15 um to about 300 um, from about 20 um to about 200 um, from about 30 um to about 100 um, from about 40 um to about 85 um, or from about 50 um to about 75 um.

27. The process of any one of claims 1 or 3 to 26, wherein the reaction mixture comprises a solvent selected from the group consisting of water, an organic solvent, and a mixture thereof.

28. The process of claim 27, wherein the solvent is a mixture of water and an organic solvent, wherein the organic solvent is a water-miscible organic solvent selected from the group consisting of a water-miscible ether, a water-miscible ketone, a water-miscible organic acid, a water-miscible aldehyde, and a water-miscible ester.

29. The process of any one of claims 1 or 3 to 28, wherein the reaction is carried out under a partial pressure of hydrogen in the range of from about 200 psia (1379 kPa) to about 2000 psia (13790 kPa) or about 600 psia (4137 kPa) to about 1100 psia (7584 kPa).

30. The process of any one of claims 1 or 3 to 29, wherein the reaction is carried out at a temperature in the range of from about 50°C to about 500°C, from about 50°C to about 400°C, from about 50°C to about 200°C, from about 50°C to about 150°C, or from about 50°C to about 140°C, from about 60"C to about 140°C, from about 60°C to about 130°C, from about 65°C to about 130°C, from about 65°C to about 125 C, from about 70°C to about 125 C, or from about 90°C to about 120°C.

31. The process of any one of claims 1 or 3 to 30, wherein the reaction is carried out in a continuous reactor system.

32. The process of claim 31 , wherein the continuous reactor system comprises a fixed bed reactor.

33. The process of claim 31 or 32, wherein the continuous reactor system comprises at least two serially positioned fixed bed reactors, wherein at least one reaction condition selected from the group consisting of reaction temperature, hydrogen partial pressure, and solvent composition, differs with respect to each serially positioned fixed bed reactor.

34. The process of any one of claims 31 to 33, wherein the heterogeneous catalyst is capable of catalyzing the conversion of THFA to 1,5-pentanediol at a conversion of at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, or at least about 90% of the initial THFA conversion and at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, or at least about 90% of the initial PDO selectivity after a time on stream (TOS) period of at least about 100 hours, at a hydrogen partial pressure of about 1000 psia and a temperature of about 90°C.

35. The process of claim 34, wherein the conversion of THFA to 1 ,5-pentanediol and/or 1 ,5- pentanediol selectivity is evaluated after a TOS period of about ISO hours, about 200 hours, about 250 hours, about 300 hours, about 350 hours, about 400 hours, about 450 hours, about 500 hours, about 550 hours, about 600 hours, about 650 hours, about 700 hours, about 750 hours, about 800 hours, about 850 hours, about 900 hours, about 950 hours, or about 1000 hours.

36. The process of any one of claims 31 to 35, wherein the heterogeneous catalyst exhibits a 1 ,5-pentanediol productivity level that is at least about 0.10 g

at least about

at least about 0.2 g groo/gcataiyst-hour, or at least about

hour.

37. The process of claim 36, wherein the 1,5-pentanediol is produced at a productivity level that is greater than about

38. The process of any one of claims 31 to 37, wherein the reaction is carried out for a time on stream (TOS) period of at least about 200 hours, at least about 250 hours, at least about 300 hours, at least about 350 hours, at least about 400 hours, at least about 450 hours, at least about 500 hours, at least about 550 hours, at least about 600 hours, at least about 650 hours, at least about 700 hours, at least about 750 hours, at least about 800 hours, at least about 850 hours, at least about 900 hours, at least about 950 hours, or at least about 1000 hours.

39. The process of any one of claims 1 or 3 to 38, wherein the conversion of THFA is at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99%.

40. The process of any one of claims 1 or 3 to 39, wherein the yield of 1,5-pentanediol is at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 99%.

41. The process of any one of claims 1 or 3 to 40, wherein the reaction produces a mixture of products comprising 1,5-pentanediol, and at least a second product selected from the group consisting of 1-pentanol, 2-pentanol, 1,4-pentanediol, and 1 ,2-pentanediol.

42. The process of claim 41, wherein the heterogeneous catalyst exhibits a selectivity for 1 ,2-pentanediol that is less than about 2%.

43. The process of claim 41 or 42, wherein the mixture of products comprises 1,5- pentanediol and 1 ,2-pentanediol, and the yield of 1 ,2-pentanediol is from about 0.1% to about 5%, from about 0.1 % to about 4%, from about 0.1 % to about 3%, from about 0.1 % to about 2%, or from about 0.1% to about 1%.

44. The process of any one of claims 41 to 43, wherein the mixture of products comprises 1,5-pentanediol and 1,2-pentanediol, and the 1,5-pentanediol and 1 ,2-pentanediol are present in the mixture of products at a molar ratio of 1,5-pentanediol to 1,2-pentanediol that is in the range of from about 5:1 to about 500:1, from about 10:1 to about 500:1, from about 15:1 to about 500: 1 , from about 20: 1 to about 500: 1, from about 25: 1 to about 500: 1, from about 50: 1 to about 500: 1 , or from about 75: 1 to about 500: 1.

45. The process of any one of claims 1 or 3 to 44, wherein the reaction produces a mixture of products, the process further comprising:

separating the 1,5-pentanediol from one or more of the other components of the reaction mixture.

46. A catalyst comprising:

a first metal and rhenium on a shaped catalyst support comprising carbonaceous material; and

a shell metal layer disposed directly adjacent to and at least partially covering the outer surface of the shaped catalyst support;

wherein the first metal is selected from the group consisting of rhodium and iridium, the shell metal layer comprises one or more metals selected from the group consisting of rhodium, iridium, rhenium, mixtures of rhodium and rhenium, and mixtures of iridium and rhenium, and the shell metal layer is enriched in content of said one or more metals relative to the concentration of said one or more metals in regions of the catalyst other than the shell metal layer.

47. The catalyst of claim 46, wherein the shaped catalyst support comprises carbon black.

48. The catalyst of claim 46 or 47, wherein the shell metal layer penetrates surficial pores of the shaped catalyst support, and extends beyond the outer surface of the support.

49. The catalyst of claim 46 or 47, wherein the shell metal layer extends substantially only inwards into the shaped catalyst support.

50. The catalyst of any one of claims 46 to 49, wherein the shell metal layer has a thickness in the range of from about 10 μm. to about 400 μm., from about 50 μm. to about 150 μm., from about 50 μm to about 100 μηι, from about 15 μm. to about 300 μm., from about 20 μηι to about 200 um, from about 30 um to about 100 um, from about 40 um to about 85 μm., or from about 50 pinto about 75 um.

51. The catalyst of any one of claims 46 to 50, wherein the BET specific surface area of the shaped catalyst support is in the range of from about 50 m²/g to about 200 m²/g, from about 75 m²/g to about 200 m²/g, from 75 m²/g to about 180 m²/g, from about 75 m²/g to about 150 m²/g, from about 75 mVg to about 125 m²/g, from about 85 m²/g to about 200 m²/g, from about 85 m²/g to about 150 m²/g, or from about 85 m²/g to about 125 m²/g.

52. The catalyst of any one of claims 46 to 51 , wherein the catalyst has an average pore diameter in the range of from about 10 ran to about 50 nm or from about 10 to about 25 nm.

53. The catalyst of any one of claims 46 to 52, wherein rhenium constitutes from about 0.25 wt.% to about 6 wt.%, from about 0.5 wt.% to about 6 wt.%, from about 1 wt.% to about 6 wt.%, from about 2 wt.% to about 6 wt.%, from about 3 wt.% to about 6 wt.%, from about 3 wt.% to about 5 wt.%, or from about 4 wt.% to about 5 wt.% of the total weight of the catalyst.

54. The catalyst of any one of claims 46 to 53, wherein the first metal is rhodium and the rhodium constitutes from about 0.25 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%,from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, from about 3 wt.% to about 5 wt.%, from about 4 wt.% to about 5 wt.% of the total weight of the catalyst.

55. The catalyst of claim 46 to 54, wherein the weight ratio of rhenium to rhodium is from about 0.5:1 to about 5:1, from about 0.6:1 to about 4:1, from about 0.7:1 to about 3:1, from about 0.8:1, to about 2:1, from about 0.9:1 to about 2:1, from about 1.1:1 to about 2:1, from about 1.1:1 to about 1.8:1, from about 1.1:1 to about 1.7: 1, from about 1.2:1 to about 1.6:1, or from about 1.3:1 to about 1.5:1.

56. The catalyst of any one of claims 46 to 53, wherein the first metal is iridium and the iridium constitutes from about 0.25 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, from about 1 wt.% to about 5 wt.%, from about 2 wt.% to about 5 wt.%, or from about 2 wt.% to about 4 wt.% of the total weight of the catalyst.

57. The catalyst of claim 56, wherein the weight ratio of rhenium to iridium is in the range of from about 0.5:1 to about 5:1, from about 0.6:1 to about 4:1, from about 0.7:1 to about 3:1, from about 0.8:1, to about 2:1, or from about 0.9:1 to about 2:1.

58. The catalyst of any one of claims 46 to 57, wherein the catalyst further comprises a promoter metal selected from the group consisting of copper, bismuth, and combinations thereof.

59. The catalyst of claim 58, wherein the promoter metal constitutes from about 0.005 wt.% to about 2 wt.%, from about 0.01 wt.% to about 1 wt.%, from about 0.01 wt.% to about 0.75 wt.%, or from about 0.05 wt.% to about 0.75 wt.% of the total weight of the catalyst.

60. The catalyst any one of claims 46 to 59, wherein the shaped catalyst support is an extrudate.

61. The catalyst of any one of claims 46 to 60, wherein the shaped catalyst support has a diameter in the range of from about 1 mm to about 5 mm.

62. The catalyst of any one of claims 46 to 61, wherein the catalyst is capable of catalyzing the conversion of THFA to 1,5-pentanediol at a conversion of at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, or at least about 90% of the initial THFA conversion and at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, or at least about 90% of the initial PDO selectivity after a time on stream (TOS) period of at least about 100 hours, at a hydrogen partial pressure of about 1000 psia and a temperature of about 90°C.

63. The catalyst of claim 62, wherein the conversion of THFA to 1,5-pentanediol and/or 1,5- pentanediol selectivity is evaluated after a TOS period of about 150 hours, about 200 hours, about 250 hours, about 300 hours, about 350 hours, about 400 hours, about 450 hours, about 500 hours, about 550 hours, about 600 hours, about 650 hours, about 700 hours, about 750 hours, about 800 hours, about 850 hours, about 900 hours, about 950 hours, or about 1000 hours.

64. The catalyst of claim 62 or 63, wherein the heterogeneous catalyst exhibits a 1,5- pentanediol productivity level that is at least about

at least about 0.15

at least about

or at least about

65. The catalyst of claim 64, wherein the 1,5-pentanediol is produced at a productivity level that is greater than about