Activated carbon-supported catalyst for aqueous-phase reforming of alcohols

Abstract

The present disclosure relates to an activated carbon-supported catalyst comprising 5 to 30 wt.% of nickel, 0.5 to 2 wt.% of platinum, and a bead-shaped activated carbon, wherein the nickel and the platinum are dispersed and supported on the bead-shaped activated carbon. The present disclosure also relates to a method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols using the activated carbon-supported catalyst of the present disclosure.

Description

ACTIVATED CARBON-SUPPORTED CATALYST FOR AQUEOUS-PHASE REFORMING OF ALCOHOLSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of Singapore application no. 10202403816T filed on 5 December 2024, the contents of it being hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure generally relates to an activated carbon-supported catalyst and a method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols using the catalyst.BACKGROUND

[0003] The global transition toward cleaner and more sustainable energy systems has intensified the demand for high-purity hydrogen as a versatile and carbon-free energy carrier. Hydrogen offers significant advantages in terms of energy efficiency and environmental performance, however, its large-scale utilization remains limited by several technical and logistic challenges. These include its low volumetric energy density, the high energy penalty associated with liquefaction, and the inherent safety risks due to its high flammability.

[0004] One approach to mitigating these challenges is the use of liquid hydrogen carriers, which can store and transport hydrogen in a chemically bound form and release it upon demand. Among various hydrogen generation pathways, caustic aqueous-phase reforming (CAPR) of alcohols derived from renewable biomass has emerged as a promising process for decentralized hydrogen production. CAPR enables the conversion of oxygenated hydrocarbons into hydrogen and other value-added gases under relatively mild conditions, offering advantages in process efficiency, cost, and environmental impact.

[0005] Nevertheless, the practical implementation of CAPR is hindered by issues related to catalyst stability and durability under caustic hydrothermal environments. The active catalyst components are prone to sintering, leaching, or structural degradation during prolonged operation, which adversely affects hydrogen yield and selectivity.

[0006] It is therefore desirable to provide a catalyst and a method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols using the catalyst, that seek to address at least one of the problems described hereinabove, or at least to provide an alternative solution.SUMMARY

[0007] In accordance with a first aspect of the present disclosure, an activated carbon- supported catalyst is provided. The catalyst comprises 5 to 30 wt.% of nickel; 0.5 to 2 wt.% of platinum; and a bead-shaped activated carbon, wherein the nickel and the platinum are dispersed and supported on the bead-shaped activated carbon.

[0008] In accordance with a second aspect of the present disclosure, a method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols is provided. The method comprises providing an activated carbon-supported catalyst comprising 5 to 30 wt.% of nickel and 0.5 to 2 wt.% of platinum, supported on a bead-shaped activated carbon; immersing the activated carbon-supported catalyst in an aqueous solution containing potassium carbonate and water at a temperature ranging from 200 to 250 °C under pressure; and contacting an alcohol feedstock with the activated carbon-supported catalyst in the aqueous solution containing the potassium carbonate and the water to produce hydrogen gas.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various embodiments of the present disclosure are described hereinbelow in the detailed description with reference to the following drawings:FIG. 1 is a scanning electron microscope (SEM) image showing the morphology of the beadshaped activated carb on- supported catalyst in accordance with various embodiments of the present disclosure.FIG. 2 illustrates the Rietveld refinement results of the X-ray diffraction (XRD) pattern of the catalyst comprising 20 wt.% Ni - 2 wt.% Pt / A-BAC MP. The Rietveld refinement statistics are as follows: Rwp= 5.73, Rexp= 5.36, / y = 1 .1428, and GoF = 1 .0690.FIG. 3 illustrates the Rietveld refinement results of the X-ray diffraction (XRD) pattern of the catalyst comprising 20 wt.% Ni - 1 wt.% Pt / A-BAC MP. The Rietveld refinement statistics are as follows: Rwp= 4.94, Rexp= 4.60, = 1.1533, GoF = 1.0739.FIG. 4 illustrates the Rietveld refinement results of the X-ray diffraction (XRD) pattern of the catalyst comprising 20 wt.% Ni - 1 wt.% Pt / DARCO 100 Mesh. The Rietveld refinement statistics are as follows: Rwp= 5.28, Rexp = 4.82, / = 1.2000, GoF = 1.0954.DESCRIPTION

[0010] The following description sets forth exemplary methods, parameters, and the like. The embodiments are described in sufficient detail to enable those skilled in the art to practise the invention. Other embodiments may be utilized, and structural and logical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0011] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0012] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0013] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance, e g. within 10% of the specified value.

[0014] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0015] By “comprising” it is meant including, but not limited to, whatever follows the word “comprising”. Thus, use of the term “comprising” indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present.

[0016] By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of’. Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present.

[0017] The present disclosure relates to an activated carb on- supported catalyst. The catalyst exhibits enhanced stability and high catalytic activity in caustic aqueous-phase reforming (CAPR) of alcohols. The catalyst enables the production of high-purity hydrogen under caustic aqueous-phase reforming conditions, having a carbon monoxide content as low as about 100 ppm.

[0018] In various embodiments, the activated carbon-supported catalyst comprises 5 to 30 wt.% of nickel and 0.5 to 2.0 wt.% of platinum, based on the total weight of the activated carbon-supported catalyst, and a bead-shaped activated carbon, wherein the nickel and the platinum are dispersed and supported on the bead-shaped activated carbon.

[0019] In various embodiments, the bead-shaped activated carbon has an average particle size ranging from 0.2 to 1.0 mm.

[0020] In various embodiments, the bead-shaped activated carbon has an average pore size ranging from 2.5 to 3.0 nm, with a measurement uncertainty of ± 0.06 nm.

[0021] In various embodiments, the bead-shaped activated carbon has a surface area of more than 1000 m2 / g. In some embodiments, the bead-shaped activated carbon has a surface area ranging from 1000 m2 / g to 1200 m2 / g.

[0022] In various embodiments, the bead-shaped activated carbon has a micropore surface area of more than 800 m2 / g. In some embodiments, the bead-shaped activated carbon has a micropore surface area ranging from 801 m2 / g to 870 m2 / g.

[0023] In various embodiments, the bead-shaped activated carbon may be selected from commercially available activated carbons having a spherical morphology. Suitable examples include bead-shaped activated carbons produced by known carbonization and activation processes, having an average particle size of 0.2 to 1.0 mm, an average pore size of 2.5 to 3.0 nm and a surface area of more than 1000 m2 / g, or within the range of 1000 m2 / g to 1200 m2 / g.

[0024] In various embodiments, the bead-shaped activated carbon has a composition comprising carbon, hydrogen and oxygen. In some embodiments, the bead-shaped activated carbon may comprise 90 to 95 wt.% of carbon, 0.8 to 1.6 wt.% of hydrogen and 0 to 10 wt.% of oxygen.

[0025] In various embodiments, the bead-shaped activated carbon may have a full density ranging from 0.5 to 0.7 g / ml, a hardness of 95% or higher, a 5% or less reduction on drying and 0.05% or less or less than 500 ppm residue on ignition (ash).

[0026] The bead-shaped activated carbon may be selected from commercially available sources having grades, specifications and / or properties comparable to those of the bead-shaped activated carbon described herein. Bead-shaped activated carbon with comparable grades exhibiting similar particle size, surface area and pore size characteristics may be employed.

[0027] In some embodiments, the nickel present in the activated carbon-supported catalyst may range from 5 to 20 wt.%, based on the total weight of the activated carbon-supported catalyst. The nickel has a particle size ranging from 5 to 30 nm.

[0028] In various embodiments, the platinum exists as an alloy with nickel. The nickelplatinum alloy, represented by NixPty, wherein Y ranges from 0.05 to 0.1, and X is 1-Y, has an average particle size ranging from 4 to 9 nm.

[0029] In various embodiments, the nickel and the platinum are dispersed and supported on the bead-shaped activated carbon by wet impregnation of the bead-shaped carbon support. In some embodiments, a mixture comprising the bead-shaped carbon support and the desired metal precursors is prepared prior to subjecting the mixture to wet impregnation in a vessel. The resulting impregnated activated carbon support is then subjected to thermal treatment under a continuous flow of argon gas. Upon reaching a temperature of 390 to 410 °C, preferably 400 °C, hydrogen gas is introduced and reduction continued while maintaining an inert atmosphere in the vessel.

[0030] In various embodiments, the activated carbon-supported catalyst is configured for use in caustic aqueous-phase reforming (CAPR) of alcohols for producing hydrogen gas. The alcohols suitable for use in the process may include, but not limited to, methanol, ethanol and polyols such as ethylene glycol, glycerol, and sorbitol. The activated carbon-supported catalyst demonstrates improved stability in the CAPR of alcohols and has improved resistance to deactivation after being soaked in aqueous potassium carbonate (K2CO3).

[0031] In a second aspect, a method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols using the catalyst of the present disclosure is provided. The method comprises providing an activated carbon-supported catalyst comprising 5 to 30 wt.% of nickel and 0.5 to 2 wt.% of platinum, supported on a bead-shaped activated carbon; immersing the activated carbon-supported catalyst in an aqueous solution containing potassium carbonate and water at a temperature ranging from 200 to 250 °C under pressure; and contacting an alcohol feedstock with the activated carbon-supported catalyst in the aqueous solution containing the potassium carbonate and the water to produce hydrogen gas.

[0032] In various embodiments, the aqueous solution containing the potassium carbonate and the water is an electrolyte.

[0033] In various embodiments, the activated carbon-supported catalyst is immersed in the aqueous solution containing the potassium carbonate at 225 °C for a duration ranging from 1 to 1000 hours.

[0034] The catalyst of the present disclosure exhibits strong performance in caustic aqueous- phase reforming (CAPR) of alcohols and demonstrates exceptional hydrothermal stability. The carbon monoxide content in the gas produced during the CAPR process is remarkably low, at less than 100 ppm. This represents a significant improvement in both the stability and efficiency of hydrogen production processes under caustic aqueous conditions. The use of bead-shaped activated carbon as the catalyst support, in combination with the bimetallic Ni and Pt composition, results in a highly active and durable catalyst capable of sustaining a high hydrogen production rate that compares favourably with state-of-the-art catalysts. In addition, the catalyst effectively minimizes the carbon footprint by reducing unwanted by-products, such as carbon dioxide, through in situ carbon dioxide capture by carbonate. The catalyst maintains its structural integrity and is resistant to deactivation under caustic hydrothermal conditions.

[0035] To facilitate a better understanding of the present disclosure, the following examples of specific embodiments are given. In no way should the following examples be read to limit or define the entire scope of the disclosure. One skilled in the art will recognize that the examples set out below are not an exhaustive list of the embodiments of this disclosure.EXAMPLESExample 1

[0036] Preparation of Activated Carbon-supported Catalyst

[0037] The activated carbon-supported catalyst was prepared by a wet impregnation method using bead-shaped activated carbon as the support. A predetermined amount (in grams) of the required metal nitrates was added to a suitable vessel such that the total amount of metalprecursors corresponded to the desired weight percent (wt.%) of metal loading in the final catalyst. The activated carbon was then added to the solution in an amount corresponding to the remaining weight percent (wt.%) of the catalyst. Water was added until liquid water became visible in the vessel to ensure complete wetting of the activated carbon. The mixture was then placed in a 60 °C oven and allowed to stand overnight. The resulting solid was transferred to an alumina boat, and placed in a horizontal tubular furnace. A gas flow of about 30 seem was introduced, and the temperature was increased to 400 °C. Once the temperature reached 400 °C, the argon flow was stopped and replaced with hydrogen gas at the same flow rate. Reduction was continued under flowing hydrogen for 2 hours at 500 °C. After cooling to room temperature, the activated carbon-supported catalyst was obtained, which can be used directly in caustic aqueous-phase reforming (CAPR) reactions.

[0038] The bead-shaped activated carbon used in the preparation of the activated carbon- supported catalyst was commercially available from Kureha Corporation under grade A-BAC MP. In other embodiments, Kureha’ s bead-shaped activated carbon with grade A-BAC LP or equivalent bead-shaped activated carbons from other sources may be used without departing from the scope of the present disclosure.

[0039] The term “A-BAC MP” as used herein refers to bead-shaped activated carbon comprising medium size particles. The average particle size may range from 0.45 to 0.55 mm.

[0040] The term“ A-BAC LP” as used herein refers to bead-shaped carbon comprising large size particles. The average particle size may range from 0.55 to 0.65 mm.Example 2

[0041] Catalysts Comprising Different Amounts of Ni and Pt

[0042] Samples comprising different amounts of Ni and Pt, supported on bead-shaped activated carbon (B AC) of grade A-BAC MP, were prepared following the procedure described in Example 1. The compositions of the resulting samples and the corresponding test results are shown in Table 1 .

[0043] Table 1: Samples with different amounts of Ni and Pt.ding to the present disclosure Entries 8-11 are comparative examples using different

[0044] wThe amounts of Ni and Pt present in the compositions were measured in weight percent (wt.%) relative to the weight of the catalyst.

[0045] i»,iFor the stbility test, the activated carbon-supported catalyst was soaked in aqueous potassium carbonate (K2CO3) for different predetermined durations to test the stability of the catalysts. This was carried by immersing 0.5 g of activated carbon-supported catalyst in an aqueous solution containing 20.73 g of K2CO3 and 60.6 g of water. The mixture was heated and maintained at a temperature of 225 °C in a reactor, under an atmosphere of argon at an initial pressure of 2.2 MPa (22 bar) for the selected predetermined duration. The final pressure was in the range of 4.8 to 5.0 MPa (48 to 50 bar).

[0046] ^The specific activities of fresh catalyst were determined based on a two-hour average activity; The specific activities after being soaked in K2CO3 were determined based on a two-hour average activity following the addition of 9.53 g of methanol to the same reactor used in the stability test.

[0047] mThe value of 84 mmol-EE / g-cat / h obtained for Entry 10 in respect of specific activity of fresh catalyst was obtained after soaking the catalyst in K2CO3 for a duration of anaverage of 3 hours instead of 2 hours. It was projected from a 10 mL reactor result, reported in Entry 10 of Table 3.

[0048] wThe value of 83.6 mmol-EE / g-cat / h for Entry 10 in respect of specific activity of the catalyst after being soaked in K2CO3 was obtained after an average of 3 hours.

[0049] The Micro-SCl support used in one of the samples (Entry 8) was purchased from Hangzhou Catan New Material Technology. The Micro-SCl support has specifications similar to those of the A-BAC MP support (see Table 10).

[0050] For the sample using DARCO® as the suppport, DARCO 100 Mesh activated carbon (having an approximate particle size of 0.15 mm), purchased from Sigma- Aldrich, was employed.

[0051] 20 wt.% Pt / Vulcan XC72, purchased from Sigma- Aldrich, was supported on a mesoporous carbon black with a size distribution ranging from 30 to 60 nm (3 x 10'5to 6 x 10"5mm).

[0052] The results indicate that the initial performance of the catalyst comprising 20 wt.% Ni - x wt.% Pt supported on A-BAC MP exhibited a good linear correlation with the weight percentage of Pt Increasing the amount of Pt while maintaining the amount of nickel at 20 wt.% led to an increase in the specific activity of the fresh catalyst (Entry 1 to 3). The catalyst comprising 20 wt.% Ni - 2 wt.% Pt supported on A-BAC MP demonstrated strong hydrothermal stability. After 136 hours of being soaked in aqueous K2CO3 at 225 °C, under a pressure of 5 MPa (50 bar), it lost 32% of its initial activity (Entry 4). After being soaked in aqueous K2CO3 for 612 hours at about 225 °C, under a pressure of 3 MPa (30 bar), it lost about 19% of its initial activity (Entry 5).

[0053] Decreasing the Ni content to 10 or 15 wt.% (Entry 6 and Entry 7) resulted in a larger lost in activity after being soaked in aqueous K2CO3 at 225 °C, under a pressure of 5 MPa (50 bar). About 38% and 40% of the initial activity were lost, respectively (Entry 6 and 7).

[0054] Other carbon supports such as Micro-SCl and DARCO 100 Mesh were explored. The Micro-SCl support seems to be comparable to A-BAC MP support (Entry 2 vs 8) as it shows a 33% loss in activity after being soaked in aqueous K2CO3 for 185 hours (vs. 29% after 186 hours, Entry 2). DARCO 100 Mesh supported catalyst comprising 20 wt.% Ni - 1 wt.% Pt is inferior as it shows a 54% decrease in activity after being soaked in aqueous K2CO3 for a shorter duration at 1 13 hours (Entry 9).

[0055] The catalyst comprising 20 wt.% Pt supported on Vulcan XC72 (Entry 10) exhibits comparable performance to the best-performing catalysts of the present disclosure (Entry 4 and 5), but demonstrates very high caustic hydrothermal stability. However, the high cost arising from high Pt content renders such catalyst (Entry 10) less economical, thereby giving the catalysts of the present disclosure a competitive advantage.

[0056] The catalyst comprising 3 wt.% Pt supported on AI2O3 exhibits inferior performance (Entry 11), which may be attributed to the poor stability of the AI2O3 support under caustic hydrothermal conditions.Example 3

[0057] Comparative Evaluation of Catalysts

[0058] Table 2 lists some examples of other state-of-the-art catalysts reported in the literature for aqueous-phase reforming, for comparison with the catalysts of the present disclosure.

[0059] Table 2: Selected comparison with other state-of-the-art catalysts.

[0060] Entries 4 and 5 correspond to the catalysts according to the present disclosure. These catalysts were prepared in a manner similar to that described in Example 1 .

[0061] wiThe relative specific activity was obtained by dividing the specific activity of the catalyst by that of a reference. In this case, the reference is Entry 3, with an absolute activity of 1.1 mmol-BL / g-cat / h. The absolute activity of each entry can be obtained from the relative specific activity of each entry by multiplying it with 1.1. The results show, for example, that Entry 1 exhibits an activity 2.7 times higher than that of Entry 3. All reactions were performed in a 10 mL reactor at 224 to 230 °C.

[0062] Caustic aqueous-phase reforming of methanol requires specially designed catalysts for extended stability. The state-of-the-art catalysts (Table 2) used in the aqueous-phase reforming (APR) of alcohols such as NiAhCM-VOO (Entry 1), 1 wt. Pt / Co2Al-700 (Entry 2) and Pto.o5Ceo.475Zro.47s02 (Entry 3) exhibit very low hydrogen production rate upon being soaked in aqueous K2CO3 for 66 to 71 hours, which is much lower than their corresponding reported activity in the cited literature for APR. The catalysts of the present disclosure (Entries 4 and 5), on the other hand, exhibit superior stability in caustic aqueous-phase reforming of methanol.Example 4

[0063] Comparison Between Catalysts Using the Same Type of Reactor

[0064] More data on the caustic aqueous-phase reforming of methanol were obtained in a 10 mL reactor and the results are shown in Table 3.

[0065] For the reactions listed in Table 3, 20 wt.% of methanol was used as a feedstock and the initial pressure of the reactor was set at 1 MPa (10 bar). Due to differences in reactor size and reaction conditions, these results should not be directly compared with those presented inTable 1.

[0066] Table 3: Proof-of-concept results from 10 mL micro-batch reactor.

[0067] [a]Each catalyst sample was tested under identical reaction conditions. In particular, reaction was carried out using an alcohol feedstock comprising 6.658 g of liquid containing 15 wt.% of methanol, 24.9 wt.% of K2CO3, and 60.1 wt.% of water. The reaction was performed in a 10 mL reactor equipped with a PTFE-coated magnetic stir bar operated at 200 rpm. Thereaction temperature was maintained between 224 °C and 230 °C, and the initial pressure was set at 1 x 106Pa (gauge) (10 barg).

[0068] The specific activities of the fresh catalysts and those of the catalysts after soaking in aqueous K2CO3 are summarized in Table 3. The results demonstrate the catalyst’s excellent stability and resistance to deactivation under caustic hydrothermal conditions.

[0069] Ih'Tn the test, 30 mg of catalysts were soaked in 5.658 g of 29.3 wt.% of K2CO3 and 70.7 wt.% of water.

[0070] [c]The reading of the specific activity of the fresh catalyst for Entry 3 was predicted from modelling data from Entries 2, 4 and 5 with a linear model. The specific activity of 49 was determined using 15.286 x 1 wt.% Pt in the catalyst + 33.286.

[0071] [dlThe SP1300 support was from Xiamen All Carbon Corp., while the[elMicroSC-1 support was from Hangzhou Catan New Material Technology Co. ltd.

[0072] [f|Entry 10 corresponds to a catalyst comprising 20 wt.% Pt supported on Vulcan XC72 carbon (Sigma-Aldrich).

[0073] As shown in Table 3, the beneficial effect of Pt is evident. Catalysts comprising only 1 wt.% Pt, together with 20 wt.% Ni, were capable of maintaining a hydrogen production rate of about 3.7 times higher than that of the catalyst comprising only 20 wt.% Ni (Table 3, Entry 1 vs. Entry 3), after being soaked in aqueous K2CO3 for more than 90 hours at a high temperature ranging from 224 to 230 °C and at an initial pressure of 1 x 106Pa (gauge) (10 barg). The increasing activity of fresh catalyst with increasing Pt wt.% is similar to that in the 300 mL reactor (Table 1, Entries 2 to 4). A related support A-BAC LP gives superior performance and stability (Entry 6).

[0074] Other carbon supports, such as SP1300 and DARCO 100 mesh, exhibited inferior performance (Entries 7 and 8), whereas Micro-SCl demonstrated promising stability and catalytic activity (Entry 9). Catalyst comprising 20 wt.% Pt support on Vulcan XC72 (graphitized carbon), within the limit of experimental error, seems to have a very high resistanceto caustic hydrothermal deactivation (Entry 10). The results also show that without nickel, 3 wt.% Pt supported on A-BAC MP (Entry 11) is inferior to bimetallic Ni and Pt catalyst supported on A-BAC MP (Entry 3)Example 5

[0075] Gaseous Product Selectivity

[0076] Table 4 shows the gaseous product selectivity for selected catalysts. Tn general, carbon monoxide (CO) is produced in the range of 62 to 69 ppm, while carbon dioxide (CO2) and methane were produced at levels of 0.18 to 0.39 mol.%. The selectivity for hydrogen (H2) was approximately 99.4 mol.%. CO2 is likely to be formed from the incomplete capture by K2CO3, while methane could be formed from the reduction of CO2 or CO by the catalysts which contain Ni in the presence of the hydrogen produced.

[0077] Table 4: Gaseous product selectivity from gas chromatograph (GC)

[0078] The catalysts shown in Table 4 were all supported on A-BAC MP. The reaction conditions were the same as those applied to the samples shown in Table 1.

[0079] [a]The hydrogen gas (H2) produced by the process was determined from GC via TCD detector.

[0080] ^'The carbon dioxide (CO2) produced by the process was determined from GC via FID after passing the gas through an In-Jet Methanizer.Example 6

[0081] Continuous Flow Operation

[0082] The results obtained after about 262 hours’ time on stream (TOS) for the CAPR process conducted in a fixed-bed reactor were presented in Table 5.

[0083] The results show that the catalysts of the present disclosure (for example, 20 wt.%Ni - 2 wt.% Pt / A-BAC MP and others) are capable of maintaining a specific hydrogen production rate exceeding 90 mmol-IL / g-cat / h after 262 hours TOS. The hydrogen selectivity was about 99.2%, with methane (CEU) being the main gaseous side product. The selectivity toward CO and CO2 was less than 40 ppm.

[0084] Table 5: CAPR in a fixed-bed reactor

[0085] The CAPR of alcohol using the activated carbon-supported catalyst of the present disclosure was carried out in a fixed-bed reactor under the following conditions:Parameter ConditionTemperature : 220 °CPressure : 5.7 MPa (57 bar) of argonArgon flow rate 1 1.1 mL / minFeedstock flow rate : 0.8 mL / minFeedstock composition : 12.1 wt.% methanol, 17.2 wt.% K2CO3, and 70.7 wt.% waterDensity : 1.2 g / mLConcentration of K2CO3 : 1.5MExample 7

[0086] Caustic Aqueous-Phase Reforming (CAPR) of Ethanol

[0087] Two of the catalysts in the present disclosure were selected for testing in the CAPR of ethanol in a 10 mL reactor. The results are shown in Table 6.

[0088] Table 6: Caustic aqueous-phase reforming of ethanol

[0089] The CAPR of ethanol was carried out in a 10 mL reactor under the following conditions:Parameter ConditionTemperature : 225 °C (Entry 1), 221 °C (Entry 2)Initial Pressure : 2.0 MPa (20 bar)Reaction time : 2 hoursFeedstock composition : 20 wt.% ethanol, 23 wt.% K2CO3, and 57 wt.% water

[0090] The catalyst used in Entry 1 was recycled after being subjected to one cycle of methanol CAPR before the ethanal CAPR test.

[0091] The results indicate that the distribution of Hi and CH4 was 1 : 1. However, it appears that 20 wt.% Ni -1 wt.% Pt supported on Micro-SCl also exhibited high selectivity toward H2 as compared to the A-BAC MP supported catalyst, which produced an approximately 1 : 1 H2 to CH4 ratio. Accordingly, the Micro-SCl support may also be employed for preparing the activated carb on -supported catalyst of the present disclosure.Example 8

[0092] Key Characterization Data

[0093] The key characterization data of the various catalysts are summarized in Table 7.

[0094] Inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis of the metal content, performed after catalyst digestion in aqua regia, is presented together with the H2 chemisorption results for selected catalysts. For the composition comprising 20 wt.% Ni - 1 wt.% Pt composition, the A-BAC MP support affords a freshly reduced catalyst exhibiting superior H2 adsorption capacity, metal dispersion, and surface metal area compared to catalysts supported on SP1300 and DARCO carbon.

[0095] Table 7: Key characteristics data

[0096] The grain sizes of the metal particles in the catalysts and the phase composition of the catalysts were determined by X-ray diffraction (XRD) analysis and Rietveld refinement.The corresponding results are presented in Table 8 and Table 9, respectively.

[0097] Table 8: Grain sizes of metal particles in catalysts

[0098] The grain size was determined from the (111) crystal plane by fitting the diffraction peak to an ellipsoidal crystallite shape.

[0099] Table 9: Phase composition of catalysts

[0100] FIG. 2, FIG. 3 and FIG. 4 illustrate selected Ri etv eld refinement results.

[0101] FIG. 2 shows the results of the catalyst comprising 20 wt.% Ni - 2 wt.% Pt / A-BAC MP. FIG. 3 shows the results of the catalyst comprising 20 wt.% Ni - 1 wt.% Pt / A-BAC MP, while FIG. 4 shows the results of the catalyst comprising 20 wt.% Ni - 1 wt.% Pt / DARCO 100 Mesh.Example 9

[0102] Texture Properties of the Support

[0103] The texture properties of the support derived from the fitting of nitrogen adsorptiondesorption measurements of the various catalysts are summarized in Table 10.

[0104] The catalysts that were synthesized from A-BAC MP and Micro-SCl supports exhibit exceptional stability and activity and have similar texture properties. The pore size of the support (A-BAC MP) employed in the catalyst of the present disclosure seems to be the smallest amongst the various carbon supports tested.

[0105] Table 10: Texture properties of the supporttT BET surface area; ^ -plot method; E average of JH adsorption and desorption.

[0106] The activated carbon-supported catalyst of the present disclosure demonstratesexcellent performance in CAPR and possesses exceptional hydrothermal stability. The catalyst is capable of maintaining a specific hydrogen production rate exceeding 80 mmol Hi / g-cat / h or 90 mmol I b / g-cat / li over a continuous time on stream (TOS) of 450 hours, or 262 hours, respectively, with no observable loss of activity throughout the test period. This result demonstrates the excellent stability and durability of the catalyst under prolonged caustic aqueous-phase reforming conditions. The catalyst enables the production of high-purity hydrogen from sustainable alcohol feedstocks, which is suitable for use in fuel-cell-based power generation.

[0107] Although embodiments of the invention have been shown and described, the invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that various modifications and variations can be made to the embodiments of the invention without departing from the scope of the invention, the scoop of which is set forth in the following claims.

Claims

Claims1. An activated carb on- supported catalyst comprising:5 to 30 wt.% of nickel;0.5 to 2 wt.% of platinum; and a bead-shaped activated carbon, wherein the nickel and the platinum are dispersed and supported on the bead-shaped activated carbon.

2. The activated carbon-supported catalyst of claim 1, wherein the bead-shaped activated carbon has an average particle size ranging from 0.2 to 1.0 mm.

3. The activated carbon-supported catalyst of claim 1, wherein the bead-shaped activated carbon has an average pore size ranging from 2.5 to 3.0 nm.

4. The activated carbon-supported catalyst of claim 1, wherein the bead-shaped activated carbon has a surface area ranging from 1000 m2 / g to 1200 m2 / g, and a micropore surface area of more than 800 m2 / g.

5. The activated carbon-supported catalyst of claim 1, wherein the nickel is present in an amount ranging from 5 to 20 wt.%, based on the total weight of the activated carbon-supported catalyst.

6. The activated carbon-supported catalyst of claim 1, wherein the activated carbon- supported catalyst is configured for use in caustic aqueous-phase reforming of alcohol for producing hydrogen gas.

7. The activated carbon-supported catalyst of claim 6, wherein the alcohol is selected from the group consisting of methanol, ethanol, polyols, and combinations thereof.

8. The activated carbon-supported catalyst of claim 1, wherein the platinum exists as an alloy with nickel, represented by NixPty, wherein Y ranges from 0.05 to 0.1, and X is 1-Y, and wherein the nickel-platinum alloy has an average particle size ranging from 4 to 9 nm.

9. A method of producing hydrogen gas from caustic aqueous-phase reforming of alcohols, the method comprising: providing an activated carbon-supported catalyst comprising 5 to 30 wt.% of nickel and 0.5 to 2 wt.% of platinum, supported on a bead-shaped activated carbon; immersing the activated carbon-supported catalyst in an aqueous solution containing potassium carbonate and water at a temperature ranging from 200 to 250 °C under pressure; and contacting an alcohol feedstock with the activated carbon-supported catalyst in the aqueous solution containing the potassium carbonate and the water to produce hydrogen gas.

10. The method of claim 9, wherein the activated carbon-supported catalyst is immersed in the aqueous solution containing the potassium carbonate for a duration ranging from 1 to 1000 hours.

11. The method of claim 9, wherein the bead-shaped activated carbon has an average particle size ranging from 0.2 to 1.0 mm.

12. The method of claim 9, wherein the bead-shaped activated carbon has an average pore size ranging from 2.5 to 3 0 nm.

13. The method of claim 9, wherein the bead-shaped activated carbon has a surface area ranging from 1000 m2 / g to 1200 m2 / g, and a micropore surface area of more than 800 m2 / g.

14. The method of claim 9, wherein the alcohol feedstock is selected from the group consisting of methanol, ethanol, polyols, and combinations thereof.

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