Novel hybrid sorbent-catalyst composition and method of making thereof for blue hydrogen production

Abstract

The present invention relates to a process for preparation of dual functional materials (DFMs) that exhibit both catalytic activity and CO2 sorption capacity, specifically designed for blue H2 production via sorption-enhanced steam methane reforming. Process for preparation of dual functional materials (DFMs) consisting the CO2 sorbent, calcium oxide (CaO) derived from biowaste resources, including snail shells, seashells, or eggshells, while nickel (Ni), derived from nickel nitrate hexahydrate, serves as the catalyst. The dual functional materials (DFMs) are prepared by combining the catalyst and sorbent through various methods, including wet mixing (WM), wet impregnation (WI), and the sol-gel (SG) method. Comparative studies demonstrated that the combined sorbent-catalyst composition (CSCC) synthesized through WI exhibits superior performance in terms of both CH4 conversion and H2 purity compared to those derived through WM and SG methods.

Description

[0001] P_W0100790

[0002] NOVEL HYBRID SORBENT-CATALYST COMPOSITION AND METHOD OF MAKING THEREOF FOR BLUE HYDROGEN PRODUCTION

[0003] FIELD OF INVENTION

[0004] The present invention relates to the dual functional materials (DFMs) derived from biowaste such as snail shell or seashell or eggshell with combined catalytic activity and CO2 sorption capacity and its application in the field of pure H2 production with inherent CO2 capture through sorption enhanced steam methane reforming. More particularly, the present invention relates to the dual-functional materials (DFMs), and in particular to a combined sorbent catalyst composition (CSCC) with combined catalytic activity and CO2 sorption capacity for sorption-enhanced steam methane reforming (SE-SMR). Further, present invention provides a process for preparation of dual functional materials (DFMs) using calcium oxide (CaO) derived from biowaste sources such as snail shells, seashells, or river shells as the CO2 sorbent, and nickel (Ni) sourced from nickel nitrate hexahydrate as the catalyst.

[0005] BACKGROUND OF THE INVENTION

[0006] According to the International Energy Agency (IE A) report 2023, the global H2 market demand stood at 92 million tonnes in 2022 and is expected to reach 130 million tonnes by 2032 at a cumulative annual growth rate (CAGR) of 3.58% (IEA 2023). Currently, 95% of the commercial H2 production is met through conventional steam methane reforming (SMR) process (termed as grey H2), emitting 8-12 kg of CCh / kg of H2 (Prato-Garcia et al. 2023). Although SMR is a well-established process, its overall carbon footprint is predominantly attributed to its endothermic nature, severe operating conditions (high temperature, 800-1000°C and pressure of 20-30 atm), requirement for shift reactors and gas separation units such as pressure swing adsorption (PSA), thereby making the process highly energy and cost-intensive. The proposed idea is aimed at developing an efficient, and eco-friendly process for high purity H2 production with lower carbon footprint through sorption enhanced steam methane reforming (SESMR). The intensified process facilitates in-situ removal of CO2 using sorbent material along with catalyst in the reformer, which tends to overcome the equilibrium limitations of reforming. Further, the exothermicity of the CO2 sorption can be utilized to partially fulfill the endothermicity of reforming.

[0007] Reference may be made to article published in Fuel Processing Technology, 131,2015,247, wherein Ni-CaO-mayenite (Ca12Al14O33) catalysts for the CO2 Sorption Enhanced Steam Methane Reforming (SE-SMR) developed using the microwave assisted self-combustionP_W0100790

[0008] method of preparation. The sorption of CO2 by CaO shifts the steam reforming and the Water Gas Shift reaction (WGS) towards H2 production and favors the heat balance of the global reaction. The CO2 sorption has been studied on materials with different CaO / Ca12Al14O33ratios and for different types of preparation. The specific surface area of materials, the temperature of Ni phases' reducibility and CO2 sorption are all essential for material efficiency. The Ni-CA75MM catalyst was the most active and stable in methane steam reforming with CO2 sorption, even at an unusually low temperature (650°C).

[0009] Reference may be made to article published in Ceramics International, 45, 2019, 7594, wherein CaO-Ca12Al14O33-Ni material with combined sorbent properties and catalyst activity was developed for H2 production from hydrocarbons via sorption enhanced steam reforming (SE-SR) with simultaneous CO2 capture. The combined sorbent-catalyst material (CSCM) was successfully prepared by multi-step approach method. At first a mixed calciumaluminium oxide (CAO) ceramic was prepared by wet mixing / intering method and used both as spacer for CaO-based sorbent and support for nickel catalyst. Subsequently, the sorbent and catalyst were prepared by wet mixing / sintering (900°C) and wet impregnation / calcination (500°C) methods, respectively.

[0010] Reference may be made to article published in Journal of Environmental Chemical Engineering, 10,2022,107651, wherein waste-derived CaO promoted Mg-Ni-Al (MNA) based hydrotalcite hybrid catalysts were synthesized by co -precipitation and wet impregnation method and tested for sorption enhanced steam methane reforming (SESMR) for hydrogen (H2) production. The catalysts were characterized using X-ray diffractometer (XRD), Field emission scanning electron miscroscopy (FESEM), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, Brauner Emmett teller (BET), laser particle size analyzer, Temperature programmed reduction (TPR), Thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Various CaO loadings varying from 0% to 15% into the MNA-based hydrotalcite catalysts (MNA HTc) were assessed for SESMR in a fixed bed reactor. The results revealed that 10%' CaO @ MNA exhibited the best performance in terms of a longer pre -breakthrough period with respect to other compositions. The CH4 fraction, H2purity, and CO2 production in the absence of CaO were marked at 60%, 55%, and 14% respectively.

[0011] Reference may be made to article published in Chemical Engineering Journal, 264, 2015, 697, wherein performance of an hybrid material CO2-sorbent and reforming catalyst under Sorption Enhanced Reforming of methane has been assessed. The material was synthesised through physical mixing of CaO, NiO and calcium cement aluminate (varying the proportionP_W0100790

[0012] CaO / NiO to produce three different solids). The materials, that presented a stable CO2 carrying capacity of 20 wt.% of the total CaO in the solid, were able to reach gas product composition very close to thermodynamical equilibrium (at 650 °C, steam to carbon ratio, S / C, of 3 and 1200 h”1CH4 spatial velocity), with H2composition over 94 vol.% (dry basis). In addition, it has also been demonstrated that the hybrid materials with NiO wt.% contents of 14 and 18.5 can fulfill the thermodynamical equilibrium at S / C ratios as low as 1.5. Finally, the 18.5% NiO material has been tested in cyclic operation, under realistic conditions by regenerating the sorbent in oxidizing conditions.

[0013] Reference may be made to article published in Journal of Environmental Management, 319,2022,115617, wherein H2-mixed CH4fuel and CaO-based CO2 sorbent were prepared in one pot by the mechanochemical reaction of pretreated clamshell or eggshell wastes (carbon and calcium source) with calcium hydride (hydrogen source) at room temperature. In the above reactions, CH4 was the sole hydrocarbon product, and its yield reached 78.23%. The H2 / CH4 ratio of the produced H2-mixed CH4fuel was tunable according to the need by changing the reaction conditions. It is inspiring that the simultaneously formed solid CaO / carbon products were efficient CaO-based sorbents, which possessed a higher CO2 adsorption capacity (49.81-58.74 wt.%) at 650 °C and could maintain good adsorption stability in 30 carbonation / calcination cycles (average activity loss per cycle of only 1.6%). The three achievements of the idea are that it can simultaneously eliminate clamshell or eggshell wastes, obtain valuable clean fuel, and acquire efficient CaO-based sorbents.

[0014] Reference may be made to article published in Journal of Environmental Management, 297, 2021,11343, wherein common eggshell waste was used as the starting material for calcium carbonate (CaCOs) source, which was purified to produce CaO. Different surfactants and amino-containing polymers were added to synthesize CaO-based adsorbents with different configurations and pore sizes. The amount of CO2 adsorbed was determined using a thermogravimetric analyzer (TGA). The results showed that the CO2 adsorption capacity of the synthetic CaO recovered from purified eggshell waste could reach 0.6 g-CO2 / g- sorbent, indicating a good adsorption capacity. CaO modified with a dopamine-containing polymer was shown to have an adsorption capacity of 0.62 g-CO2 / g- sorbent. Moreover, it showed an excellent adsorption capacity of 0.40 g-CO2 / g- sorbent, even after 10 cycles of CO2 adsorption. The present study suggests that using eggshell waste to synthesize CaO-based adsorbents forP_W0100790

[0015] effective CO2 adsorption can not only reduce environmental waste, but also have the potential to capture greenhouse gas CO2 emissions, which conforms to the principles of green chemistry. The following discussion presents a review of the existing literature pertaining to the hybrid sorbent-catalyst composition and method of making thereof for blue hydrogen production rendering an overview of the prior art references in this field. These references serve as a testament to the extensive research conducted in this area and provide valuable insights into the techniques and methodologies employed in the blue hydrogen production by using hybrid sorbent-catalyst composition. The above information disclosed is only for the enhancement of understanding of the background of the invention.

[0016] The SESMR requires two inter-connected fluidized bed reactors (FBRs) i.e., reformer and regenerator connected in a loop among which the catalyst and sorbent materials are circulated for continuous “H2 production and CO2 capture”. Despite the significant promise of SESMR for H2 production, there are currently no established commercial technologies of this nature globally, as the process offers lot of challenges in terms of optimal FBRs design and operation. Moreover, there exists a need for dual functional materials (DFMs) with combined sorbent and catalytic activities in a single grain, especially for fluidized bed operation. Further, design and synthesis of DFMs with sustained catalytic activity, sorbent capacity while maintaining the thermal and mechanical stabilities is a daunting task.

[0017] In view of the above and obviate the drawbacks of existing prior arts, present invention is for the design and process for prepartion of dual functional materials (DFMs) with combined sorbent and catalyst composition. CO2 sorbent material is derived from renewable biowaste resources such as snail shell, seashell, river shells or eggshells. The sorbent material is combined with Ni precursor as catalyst through different methods such as wet mixing, wet impregnation, and sol-gel method. Subsequently, the performance (in terms of CH4 conversion, H2 purity, and CO2 uptake) of these synthesized materials are evaluated under sorption enhanced steam methane reforming conditions. This innovation represents a significant advancement in the realm of CO2 sorbent materials and H2 production technologies, fostering efficient CO2 capture and high-purity H2 generation. The utilization of snail shell derived CO2 sorbent for the synthesis of combined sorbent catalyst composition (CSCC) introduces new dimensions to sustainable energy processes, with potential applications across diverse industrial and environmental domains.

[0018] OBJECTIVES OF THE INVENTION

[0019] The main objective of the present invention is to provides dual functional materials (DFMs)P_W0100790

[0020] with combined sorbent and catalyst composition (CSCC) derived from biowaste such as snail shell, seashell, river shell or eggshell in combination with Ni precursor as catalyst through wet mixing, wet impregnation, and sol-gel methods.

[0021] Another objective of the present invention is to provide dual functional material (DFM) with a Combined Sorbent Catalyst Composition (CSCC), where the sorbent is derived from biowaste such as snail shell, seashell, or river shell, in combination with a Ni precursor as a catalyst. Another objective of the present invention is to provide process for preparation of dual functional material (DFM) with a Combined Sorbent Catalyst Composition (CSCC), wherein synthesis is carried out using wet mixing, wet impregnation, and sol-gel methods, resulting in a Ni / CaO-Mayenite composition with range of 15-18 wt% Ni, 30-50 wt% CaO, and 55-32 wt% Mayenite (Ca12Al14O33).

[0022] Another objective of the present invention is to provide Combined Sorbent Catalyst Composition (CSCC) composition which enhances CH4conversion, H2 purity, and CO2 capture, making it suitable for sorption-enhanced steam methane reforming (SE-SMR) in blue hydrogen production.

[0023] SUMMARY OF THE INVENTION

[0024] Additional features and embodiments of the present disclosure will be better understood through the techniques and other aspects of the disclosure. Other embodiments of the invention are described in detail herein and are considered a part of the claimed disclosure.

[0025] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0026] The following is a condensed description of the disclosure to give the reader with a basic understanding. Its main goal is to present some of the principles described in this document in a simpler version as a prologue to the more extensive exposition that follows.

[0027] The present invention, and in accordance with main aspect of the present invention relates to dual functional material (DFM) with combined sorbent catalyst composition (CSCC) synthesized using wet mixing (WM), wet impregnation (WI), and sol-gel (SG) techniques, incorporating a biowaste-derived CO2 sorbent (BCS) along with a Ni-based catalyst.

[0028] In aspect of the present invention, dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) represented by the formula xNiyCaOzS, wherein:P_W0100790

[0029] (a) x represents the catalyst (Ni) fraction and is in the range of 15% to 18% by weight respectively;

[0030] (b) y represents the sorbent (CaO) fraction and is in the range of 30% to 50% by weight respectively;

[0031] (c) z represents the support material (S) fraction selected from a group consisting of Ca12Al14O33, Al2O3, or CaZrO3, and is in the range of 55% to 32% by weight respectively. In another aspect of the present invention, wherein catalyst (Ni) fraction selected from nickel nitrate or nickel acetate.

[0032] In another aspect of the present invention, wherein sorbent (CaO) fraction selected from snail shells, seashells, or river shells.

[0033] In another aspect of the present invention, wherein support material (S) fraction Ca12Al14O33is derived from aluminum nitrate and snail shells, seashells, or river shells.

[0034] In another aspect of the present invention, wherein support material (S) fraction CaZrO3is derived from zirconium nitrate and snail shells, seashells, or river shells.

[0035] In another aspect of the present invention, process for preparation of dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) comprising the step of:

[0036] a) calcining snail shell, seashell or river shell powder to obtain CaO;

[0037] b) preparing a sorbent- support material by dissolving aluminum nitrate or zirconium nitrate in distilled water (10-20 ml), adding the CaO as obtain in step (a) and stirring the solution mixture, then drying and calcining to obtained resulting slurry;

[0038] c) dissolving nickel nitrate or nickel acetate in distilled water (10-20 ml) to form a precursor solution;

[0039] d) impregnating the calcined sorbent-support material as obtained in step (b) with the nickel precursor solution as obtained in step (c) and stirring the solution mixture;

[0040] e) drying the impregnated material and then calcining the mixture to obtain dual-functional material (DFM) with combined sorbent catalyst composition (CSCC).

[0041] In another aspect of the present invention, wherein the calcination in step (b) and (e) carried out at a temperature in the range of 725°C to 925°C for a period in the range of 4 to 8 hours. In another aspect of the present invention, wherein the stirring in step (b) and (d) is carried at a temperature in the range of 80°C to 120°C for a period in the range of 2 to 4 hours.

[0042] In yet another aspect of the present invention, wherein the drying in step (b) and (e) is carried at a temperature in the range of 100°C to 120°C for a period in the range of 12 to 16 hours. In yet another aspect of the present invention, wherein the particle size of CaO in range of 30-100 micrometer.P_W0100790

[0043] In yet another aspect of the present invention provide a process for preparation of combined sorbent catalyst composition (CSCC) using wet mixing (WM), wet impregnation (WI), and solgel (SG) techniques, employing biowaste-derived CO2 sorbent (BCS) along with a Ni-based catalyst. Thermogravimetric analysis (TGA) revealed that among the various BCS, snail shell-derived CO2 sorbent (SSCS) exhibits a significantly higher CO2 uptake, rendering it an ideal sorbent material for CSCC synthesis. Among the CSCC synthesized via WM, WI, and SG methods utilizing the SSCS, CSCC-SG demonstrated the highest CO2 uptake, followed by CSCC-WM and CSCC-WI respectively. Further, the catalytic activity of these synthesized CSCC were evaluated under SESMR conditions, which revealed that CSCC-WI exhibits the highest performance, leading to the production of high-purity H2 while also demonstrating inherent CO2 capture capabilities.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a process flow diagram for preparation of biowaste derived CO2 sorbent (BCS).

[0045] FIG. 2 depicts a process flow diagram for the preparation of combined sorbent-catalyst composition using wet mixing method (CSCC-WM).

[0046] FIG. 3 depicts a process flow diagram for the preparation of combined sorbent-catalyst composition using solgel method (CSCC-SG).

[0047] FIG. 4 depicts a process flow diagram for the preparation of combined sorbent-catalyst composition using wet impregnation method (CSCC-WI).

[0048] FIG. 5 compares the CO2 uptake of snail shell derived CO2 sorbent (SSCS) and eggshell (ESCS) derived CO2 sorbent with commercial CO2 sorbent (CCS).

[0049] FIG. 6 compares the CO2 uptake of combined sorbent-catalyst composition via wet mixing (CSCC-WM), solgel (CSCC-SG), and wet impregnation (CSCC-WI) synthesized using snail shell derived CO2 sorbent with combined sorbent-catalyst composition via wet impregnation using commercial CO2 sorbent (CSCC-WI-CCS).

[0050] FIG. 7 (a) compares the performance of combined sorbent-catalyst composition via wet mixing (CSCC-WM), solgel (CSCC-SG); (b) compares the performance of wet impregnation (CSCC-WI) synthesized using snail shell derived CO2 sorbent with combined sorbent-catalyst composition via wet impregnation using commercial CO2 sorbent (CSCC-WI-CCS) under SESMR condition.

[0051] FIG. 8 compares the CO2 uptake of snail shell derived CO2 sorbent (SSCS), commercial CO2 sorbent (CCS), combined sorbent-catalyst composition via wet impregnation using snail shellP_W0100790

[0052] derived CO2 sorbent (CSCC-WI) and combined sorbent-catalyst composition via wet impregnation using commercial CO2 sorbent (CSCC-WI-CCS) over multiple cycles.

[0053] FIG. 9 (a) compares the performance of combined sorbent-catalyst composition via wet impregnation using SSCS (CSCC-WI); (b) compares the performance of combined sorbentcatalyst composition via wet impregnation using CCS (CSCC-WI-CCS) over multiple cycles under SESMR conditions.

[0054] FIG. 10 depicts XRD results of commercial CO2 sorbent (CCS), snail shell derived CO2 sorbent (SSCS), combined sorbent-catalyst composition using snail shell derived CO2 sorbent via wet mixing (CSCC-WM), sol-gel (CSCC-SG), wet impregnation (CSCC-WI), and combined sorbent-catalyst composition via wet impregnation CSCC-WI using commercial CO2 sorbent (CSCC-WI-CCS).

[0055] FIG. 11 compares XRD results of combined sorbent-catalyst composition using snail shell derived CO2 sorbent via wet impregnation (CSCC-WI) as synthesised and after 25 SESMR cycles.

[0056] FIG. 12 depicts scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) images of combined sorbent-catalyst composition via wet impregnation (CSCC-WI).

[0057] FIG. 13 (a) depicts the transmission electron microscopy (TEM) images of combined sorbentcatalyst composition using snail shell derived CO2 sorbent via wet impregnation (CSCC-WI); (b) combined sorbent-catalyst composition via wet impregnation using commercial CO2 sorbent (CSCC-WI-CCS) after multiple cycles under SESMR conditions.

[0058] DETAILED DESCRIPTION OF THE INVENTION

[0059] The following description is not to be taken in a limiting sense but is given solely for the purpose of describing the broad principles of the invention. Embodiments of the invention will be described by way of example, with reference to the above-mentioned drawings showing elements and results according to the present invention.

[0060] The foregoing detailed description of the disclosure is elaborated to provide a clear understanding to the person who is skilled in the art. Additional features, embodiments and advantages of the invention will be described hereinafter which form the subject of the claims of the disclosure, However, the set forth disclosure provide in the specification will best be understood in conjunction with the appended claims and figures as provide heretofore. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in theP_W0100790

[0061] art that such equivalent processes do not depart from the spirit and scope of the disclosure as set forth in the appended claims. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in various configurations, all of which are explicitly contemplated and make part of this disclosure.

[0062] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.

[0063] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the figures, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.

[0064] The present invention relates to dual functional material (DFM) with combined sorbent catalyst composition (CSCC) synthesized using wet mixing (WM), wet impregnation (WI), and sol-gel (SG) techniques, incorporating a biowaste-derived CO2 sorbent (BCS) along with a Ni-based catalyst.

[0065] In embodiment of the present invention, dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) represented by the formula xNiyCaOzS, wherein:

[0066] (a) x represents the catalyst (Ni) fraction and is in the range of 15% to 18% by weight respectively;

[0067] (b) y represents the sorbent (CaO) fraction and is in the range of 30% to 50% by weight respectively;

[0068] (c) z represents the support material (S) fraction selected from a group consisting of Ca12Al14O33, Al2O3, or CaZrO3, and is in the range of 55% to 32% by weight respectively. In embodiment of the present invention, wherein catalyst (Ni) fraction selected from nickel nitrate or nickel acetate.

[0069] In another embodiment of the present invention, wherein sorbent (CaO) fraction selected from snail shells, seashells, or river shells.

[0070] In another embodiment of the present invention, wherein support material (S) fraction Ca12Al14O33is derived from aluminum nitrate and snail shells, seashells, or river shells.P_W0100790

[0071] In another embodiment of the present invention, wherein support material (S) fraction CaZrO3is derived from zirconium nitrate and snail shells, seashells, or river shells.

[0072] In another embodiment of the present invention, process for preparation of dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) comprising the step of: a) calcining snail shell, seashell or river shell powder to obtain CaO;

[0073] b) preparing a sorbent- support material by dissolving aluminum nitrate or zirconium nitrate in distilled water (10-20 ml), adding the CaO as obtain in step (a) and stirring the solution mixture, then drying and calcining to obtained resulting slurry;

[0074] c) dissolving nickel nitrate or nickel acetate in distilled water (10-20 ml) to form a precursor solution;

[0075] d) impregnating the calcined sorbent-support material as obtained in step (b) with the nickel precursor solution as obtained in step (c) and stirring the solution mixture;

[0076] e) drying the impregnated material and then calcining the mixture to obtain dual-functional material (DFM) with combined sorbent catalyst composition (CSCC).

[0077] In another embodiment of the present invention, wherein the calcination in step (b) and (e) carried out at a temperature in the range of 725°C to 925°C for a period in the range of 4 to 8 hours.

[0078] In another embodiment of the present invention, wherein the stirring in step (b) and (d) is carried at a temperature in the range of 80°C to 120°C for a period in the range of 2 to 4 hours. In yet another embodiment of the present invention, wherein the drying in step (b) and (e) is carried at a temperature in the range of 100°C to 120°C for a period in the range of 12 to 16 hours.

[0079] In yet another embodiment of the present invention, wherein the particle size of CaO in range of 30-100 micrometer.

[0080] In yet another embodiment of the present invention provide a process for preparation of combined sorbent catalyst composition (CSCC) using wet mixing (WM), wet impregnation (WI), and sol-gel (SG) techniques, employing biowaste-derived CO2 sorbent (BCS) along with a Ni-based catalyst. Thermogravimetric analysis (TGA) revealed that among the various BCS, snail shell-derived CO2 sorbent (SSCS) exhibits a significantly higher CO2 uptake, rendering it an ideal sorbent material for CSCC synthesis. Among the CSCC synthesized via WM, WI, and SG methods utilizing the SSCS, CSCC-SG demonstrated the highest CO2 uptake, followed by CSCC-WM and CSCC-WI respectively. Further, the catalytic activity of these synthesized CSCC were evaluated under SESMR conditions, which revealed that CSCC-WI exhibits the highest performance, leading to the production of high-purity H2 while also demonstratingP_W0100790

[0081] inherent CO2 capture capabilities.

[0082] In yet another embodiment of the present invention discloses a process for the preparation of calcium oxide (CaO) derived from biowaste sources such as snail shells, seashells, or river shells, as illustrated in Figure- 1. Furthermore, the application of these biowaste-derived CO2 sorbents (BCS) in the synthesis of a combined sorbent catalyst composition (CSCC) using wet mixing (WM), sol-gel (SG), and wet impregnation (WI) methods is detailed in Figures 2-4, respectively.

[0083] Figure-5 provides a comparative analysis of the CO2 uptake capacity of the snail shell-derived CO2 sorbent (SSCS) in relation to eggshell-derived CO2 sorbent (ESCS) and a commercial CO2 sorbent (CCS). Additionally, the performance evaluation of CSCC synthesized via WM, WI, and SG methods utilizing SSCS is demonstrated in Figure-6, highlighting CO2 uptake, CH₄ conversion, and H2 purity. Further, Figure-7 presents the performance assessment of CSCC under sorption-enhanced steam methane reforming (SE-SMR) conditions when synthesized through different methods. Figure-8 examines the cyclic CO2 uptake performance of SSCS, CCS, CSCC-WI, and CSCC-WI-CCS, indicating their long-term stability and recyclability. Figure-9 extends this comparison to evaluate the extended-cycle performance of CSCC-WI and CSCC-WI-CCS under SE-SMR conditions, emphasizing the role of SSCS incorporation. Figure-10 illustrates X-ray diffraction (XRD) patterns for CCS, SSCS, CSCC-WM, CSCC-SG, CSCC-WI, and CSCC-WI-CCS, confirming the phase composition and structural integrity of the synthesized materials. Figure- 11 further compares XRD patterns of CSCC-WI before and after multiple SE-SMR cycles. Figure- 12 presents scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) images of CSCC-WI, revealing surface morphology and elemental distribution. Additionally, Figure-13 provides transmission electron microscopy (TEM) images comparing CSCC-WI and CSCC-WI-CCS after several SE-SMR cycles, offering insights into their microstructural evolution and stability.

[0084] EXAMPLES

[0085] The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention and therefore should not be construed to limit the scope of the present invention.

[0086] In examples, the quantities and percentages are given by weight unless stated otherwise.

[0087] EXAMPLE 1: Preparation of biowaste derived CO2 sorbent (BCS).P_W0100790

[0088] BCS was synthesized using a systematic process for obtaining high-purity calcium oxide. Initially, 5 kg of garden snail shells (with or without organic residues) were collected and soaked in hot water at 80°C for 2 hours. The shells were then rinsed with room-temperature water to eliminate dirt and organic matter. After cleaning, the shells were dried in a hot air oven at 120°C for 24 hours. To further purify the material, the dried shells were subjected to acetone washing, followed by an additional drying step at 120°C for 12 hours. The dried shells were then ground to a particle size of less than 100 pm and subsequently calcined at 900°C for 4 hours to thermally decompose CaCO₃ into CaO. The calcined material was further milled to achieve a particle size of 38 pm. The final BCS powder was characterized for its density, yielding a tap density measurement of 1.04 g / cm3. The obtained BCS was stored in an airtight container for further utilization in CSCC synthesis.

[0089] EXAMPLE 2: Preparation of combined sorbent-catalyst composition using wet mixing method (CSCC-WM).

[0090] CSCC-WM was synthesized via a wet mixing method. Initially, 71.96 g of aluminum nitrate nanohydrate {A1(NO3)3 9H2O} was placed in a beaker containing 400 mL of distilled water. To this solution, 31.72 g of snail shell derived CO2 sorbent (SSCS) was introduced, followed by the addition of 42.1 g of nickel nitrate hexahydrate {Ni(NO3)2-6H2O}. The resulting mixture was stirred at 100°C for 4 hours to ensure complete dissolution and homogeneity. The resultant material was then dried in a hot air oven at 120°C for 16 hours. After drying, the material was ground to a particle size of less than 100 pm to improve uniformity. Finally, the ground material underwent calcination at 900°C for 4 hours, resulting in the production of CSCC-WM.

[0091] EXAMPLE 3: Preparation of combined sorbent-catalyst composition using solgel method (CSCC-SG).

[0092] CSCC-SG was synthesized using the sol-gel method. Initially, 71.96 g of aluminum nitrate nanohydrate {A1(NO3)3 9H2O} was placed in a beaker, followed by the addition of 400 mL of distilled water. To this solution, 31.72 g of SSCS and 42.1 g of nickel nitrate hexahydrate {Ni(NO3)2 6H2O} were added. The mixture was stirred at 100°C for 4 hours. Following this step, 208 g of citric acid was introduced into the solution, maintaining a molar ratio of cation to citric acid at 1.2. The pH of the solution was then adjusted to 7 using nitric acid. The solution was stirred at 100°C for an additional 2 hours. Subsequently, 104 g of polyethylene glycol (PEG) was added with a mass ratio of PEG to citric acid set at 0.5, and the stirring was continued at 100°C for 48 hours. The prepared solution was then dried in a hot air oven atP_W0100790

[0093] 120°C for 12 hours. After drying, the material was ground to a particle size of less than 100 pm. Finally, the ground material underwent calcination at 900°C for 4 hours, resulting in the production of CSCC-SG.

[0094] EXAMPLE 4: Preparation of combined sorbent-catalyst composition using wet impregnation method (CSCC-WI).

[0095] CSCC-WI was synthesized using the wet impregnation method. Initially, 86.44 g of aluminum nitrate nanohydrate {A1(NO3)3 9H2O} was placed in a beaker, and 400 mL of distilled water was added. To this solution, 29.75 g of SSCS was introduced, followed by continuous stirring at 100°C for 4 hours.

[0096] The resulting mixture was then dried in a hot air oven at 120°C for 16 hours and subsequently ground to a particle size of less than 100 pm. The dried material was subjected to calcination at 750°C for 4 hours, followed by hydration with 1 mL of water per gram of compound. The hydrated material was then dried at 120°C for 12 hours and further ground to a particle size of less than 100 pm. The compound underwent a second calcination step at 900°C for 2 hours. In the next stage, 42.1 g of nickel nitrate hexahydrate {Ni(NO3)2 6H2O} was placed in a beaker containing 200 mL of distilled water. The prepared sorbent- support material was added to this solution, and the mixture was stirred at 100°C for 4 hours. The resulting material was then dried in a hot air oven at 120°C for 12 hours and ground to a particle size of less than 100 pm. Finally, the compound was subjected to calcination at 900°C for 4 hours, yielding the final CSCC-WI. The obtained material underwent a compression test, demonstrating stability up to 154 MPa. Combined sorbent- catalyst composition via wet impregnation using commercial CO2 sorbent (CSCC-WI-CCS) was synthesized using the same method as CSCC-WI, with the only difference being the substitution of CCS in place of SSCS. The obtained CSCC-WI-CCS underwent a compression test, demonstrating stability up to 150 MPa.

[0097] The CO2 uptake capacity of the synthesized sorbent materials was evaluated using thermogravimetric analysis (TGA). For this analysis, 50 mg of each material was placed in a Pt-based crucible to measure the weight change resulting from CO2 sorption. The material was exposed to a gaseous mixture of CO2 and N2 (15% CO2 by volume) at a flow rate of 50 mL / min. As illustrated in Fig. 5, the CO2 uptake of SSCS was determined to be 70 g per 100 g of material. A similar methodology was applied to evaluate the CO2 uptake of ESCS and CCS, revealing uptake values of 39 g per 100 g and 51 g per 100 g, respectively. These findings indicate that SSCS exhibits superior CO2 sorption capacity, making it an ideal candidate for synthesizing CSCC for pure H2 production via SESMR. The CO2 uptake capacity of CSCC synthesized fromP_W0100790

[0098] SSCS using wet mixing, sol-gel, and wet impregnation methods was also analyzed. The synthesized materials were denoted as CSCC-WM, CSCC-SG, CSCC-WI, and CSCC-WI-CCS, respectively. As illustrated in Fig. 6, the thermogravimetric analysis results revealed CO2 uptakes of 14.3 g per 100 g for CSCC-WM, 25.6 g per 100 g for CSCC-SG, 23.7 g per 100 g for CSCC-WI, and 13.5 g per 100 g for CSCC-WI-CCS.

[0099] EXAMPLE 5: Performance evaluation of synthesized combined sorbent-catalyst composition (CSCC).

[0100] The performance evaluation of the synthesized CSCC was conducted using a fixed-bed reactor under SESMR conditions. A total of 6.8 grams of CSCC was introduced into the reactor along with a gas mixture comprising CH₄, steam, and N₂ at respective flow rates of 27 mL / min, 81 mL / min, and 100 mL / min. The reforming process was carried out at a temperature of 650°C. A comparative analysis of the three synthesized CSCC materials is presented in Table 1 and Fig. 7, demonstrating that CSCC-WI exhibited superior performance among the synthesized materials, achieving a CH₄ conversion rate of 98% with an H₂ purity of 96.7%. Additionally, a comparative evaluation of CSCC-WI synthesized using SSCS and CCS revealed that the CO2 uptake capacity of SSCS-derived CSCC-WI was higher, leading to a higher H2 purity of 96.7% compared to 91% H₂ purity at the same CH₄ conversion rate.

[0101] Table 1: Performance comparison of the synthesized by different synthesis methods.

[0102] CO2uptake CH4conversion H2purity CSCC (gCO2 / 100g of CSCC) (%) (%) CSCC-WI 23.7 98 96.7 CSCC-WM 14.3 96 93 CSCC-SG 25.6 84 78 CSCC-WI-CCS 12.8 98 91

[0103] EXAMPLE 6: Performance evaluation of synthesized combined sorbent-catalyst composition (CSCC) over multiple cycles.

[0104] The evaluation of CO2 uptake stability for SSCS, CCS, CSCC-WI, and CSCC-WI-CCS over 50 carbonation-calcination cycles is illustrated in Fig. 8. The multi-cycle test was performed through alternating carbonation (15% CO2 in N2) and calcination (100% N2) cycles, each lasting 30 minutes at 650°C and 750°C, respectively. As expected, SSCS exhibited the highest initialP_W0100790

[0105] CO2uptake of 37 g CO2 / 100 g material in the first cycle but experienced a significant decline to 14 g CO2 / 100 g by the 37th cycle, after which it remained stable. CCS initially demonstrated a moderate CO2uptake of 31 g CO2 / 100 g, stabilizing at 8.5 g CO2 / 100 g by the 35th cycle. CSCC-WI showed an initial CO2uptake of 20.3 g CO2 / 100 g, which gradually decreased to 12.8 g CO2 / 100 g by the 25th cycle before stabilizing, while CSCC-WI-CCS began with 12.3 g CO2 / 100 g and stabilized at 8 g CO2 / 100 g by the 27th cycle. These results indicate that CSCC-WI synthesized using SSCS provides stable and reliable CO2 uptake performance over multiple cycles, highlighting its potential for long-term CO2 capture applications.

[0106] The performance evaluation of the synthesized CSCC was further examined in a fixed-bed reactor operating under SESMR conditions over 25 cycles. A total of 6.8 grams of CSCC was introduced into the reactor, accompanied by a gas mixture consisting of CH₄, steam, and N₂ at respective flow rates of 27 mL / min, 81 mL / min, and 100 mL / min. The reforming and regeneration processes were conducted for 30 minutes at temperatures of 650°C and 750°C, respectively. The comparative performance analysis of CSCC-WI and CSCC-WI-CCS is depicted in Fig. 9. The findings demonstrated that CSCC-WI maintained a high CH₄ conversion rate, declining slightly from 98% to 93%, while EH2purity stabilized at 91.3% by the 7th cycle, down from an initial 96.7%. In contrast, CSCC-WI-CCS exhibited a significant performance drop, with CH₄ conversion decreasing from -98% to -81% and EH2purity decreasing from -91% to -80% over the same period.

[0107] EXAMPLE 7: Figure- 10 shows XRD patterns for different samples, depicting the Bragg angle (29) versus intensity. The detected phases include Ca₁₂Al₁₄O₃₃ (JCPDS 09-0413), CaO (JCPDS 37-1497), and NiO (JCPDS 47-1049). The consistent presence of these phases across all materials confirms the successful incorporation of Ni, CaO, and Ca₁₂Al₁₄O₃₃ in the synthesized materials. The XRD patterns of CSCC-SG-SSCS, CSCC-WM-SSCS, CSCC-WI-SSCS, and CSCC-WI-CCS are similar, with slight variations in peak intensities and positions, indicating that the synthesis or treatment methods used (SG, WM, WI) result in minor differences in the crystalline structure. Additionally, the XRD patterns in CCS and SSCS detect the CaO phase. Fig. 11 shows XRD patterns of CSCC-WI as synthesized and after 25 SESMR cycles. In the as- synthesized state, diffraction peaks confirm the presence of NiO, CaO, and Ca₁₂Al₁₄O₃₃. After 25 SESMR cycles, new peaks of CaCO3appear, indicating CaO’s reaction with CO2. Metallic Ni is detected due to prereduction before each experiment, while persistent CaO and Ca12Al14O33peaks confirm structural stability. The absence of NiO peaks indicates no bulkP_W0100790

[0108] reoxidation, ensuring sustained catalytic activity. The formation of CaCO₃ further supports CaO’s effective CO2 capture, highlighting its dual-functional role in SESMR applications.

[0109] EXAMPLE 8: Table-2 presents the elemental analysis of SSBC (snail shells before calcination) and SSCS, emphasizing the enhanced CO2 capture performance of SSBC due to its distinctive composition. The high calcium content, accompanied by minor and trace elements, significantly contributes to the material's reactivity, thermal stability, and structural integrity. Elements such as aluminum (Al) and iron (Fe) play a crucial role in increasing the surface area and promoting catalytic activity. Additionally, strontium (Sr) and barium (Ba) help stabilize the material structure and maintain integrity during high-temperature cycles, ensuring consistent CO2 capture across multiple cycles, zinc (Zn), chromium (Cr), and manganese (Mn) further strengthen the crystal lattice, reducing degradation under temperature fluctuations. Meanwhile, nickel (Ni) and copper (Cu) significantly enhance catalytic activity. Trace elements including silver (Ag), lanthanum (La), and cerium (Ce) further increase the number of active sites, and modify surface properties, boosting CO2 capture and stability. Notably, samarium (Sm) facilitates hydroxyl group formation, enhancing surface characteristics, thermal stability, and adsorption capacity. Rare earth elements like praseodymium (Pr) and neodymium (Nd), though present in very low concentrations, contribute to the sorbent’s basicity and stability, ensuring effective CO2 adsorption. This unique composition of SSBC and SSCS offers superior CO2 capture performance, ensuring higher reactivity, better structural stability, and increased catalytic efficiency, making them more suitable for long-term CO2 capture applications compared to CCS for long-term industrial applications.

[0110] Table 2: Elemental Analysis of shells and BCS using ICP-MS Element SSBC (%) SSCS (%)

[0111] Ca 98.0612 98.39573 Al 0.46 0.23

[0112] Fe 0.66 0.72

[0113] Sr 0.45 0.42

[0114] Ba 0.046 0.026P_W0100790

[0115] Zn 0.023 0.0046

[0116] Cr 0.0197 0.065

[0117] Mn 0.0148 0.014

[0118] Ni 0.05 0.022

[0119] Cu 0.19 0.0811

[0120] Ag 0.0092 0.0077

[0121] La 0.01 0.009

[0122] Ce 0.005 0.004

[0123] Pr 0.00013 0.0001 Nd 0.00056 0.0004

[0124] Sm 0.00043 0.00037

[0125] EXAMPLE 9: The BET surface area (SBET) and BJH cumulative pore volume (VBJH) analysis presented in Table 3 offers important insights into the structural characteristics and stability of various materials over repeated SESMR cycles. SSBC demonstrates an initial SBET of 17.424 m2 / g and a VBJH of 0.081 cm3 / g, highlighting its high surface area and pore volume, which are advantageous for catalytic applications. CCS starts with a lower SBETof 15.315 m2 / g and a VBJH of 0.059 cm3 / g, indicating a comparatively reduced surface area. SSCS shows similar characteristics to SSBC, with an initial SBET of 17.213 m2 / g and a VBJH of 0.076 cm3 / g, suggesting good initial porosity. The CSCC-WI sorbent, as synthesized, has an initial BET surface area of 16.848 m2 / g and a BJH cumulative pore volume of 0.069 cm3 / g. After a single SESMR cycle, it shows slight reduction to 15.401 m2 / g in surface area and 0.058 cm3 / g in pore volume. Following 25 SESMR cycles, further minor decreases are observed, with the surface area reaching 13.212 m2 / g and the pore volume reducing to 0.034 cm3 / g. These minimal reductions indicate that CSCC-WI retains a high degree of structural integrity and stability after repeated use, affirming its suitability for multi-cycle applications. In comparison, the CSCC-WI-CCS sorbent, as synthesized, begins with a BET surface area of 14.825 m2 / g and a BJH pore volume of 0.052 cm3 / g. After the first SESMR cycle, these values decrease more significantly to 11.485 m2 / g and 0.038 cm3 / g, respectively, with further reductions after 25 SESMR cycles, ultimately reaching a surface area of 8.254 m2 / g and a pore volume of 0.021 cm3 / g. Although CSCC-WI-CCS demonstrates considerable resilience across multiple SESMR cycles, the retention of surface area and pore volume in CSCC-WI is comparatively higher, highlighting its superior structural stability and durability. Thus, the results clearly FavorP_W0100790

[0126] CSCC-WI as a more robust and reliable material for repeated catalytic applications, especially where multi-cycle operation is required in processes such as steam methane reforming with inherent CO2 capture.

[0127] Table 3: Measured BET surface area (SBET) BJH cumulative volumes (VBJH)

[0128] SBET VBJH

[0129] Material

[0130] [m2g-1] [cm3g-1]

[0131]

[0132] SSBC 17.424 0.081 CCS 15.315 0.059 SSCS 17. 213 0.076 CSCC-WI As synthesized 16.848 0.069 CSCC-WI After 1stSESMR Activity 15.401 0.058 CSCC-WI After 25thSESMR Activity 13.212 0.034 CSCC-WI-CCS As synthesized 14.825 0.052 CSCC-WI-CCS After 1stSESMR Activity 11.485 0.038 CSCC-WI-CCS After 25thSESMR Activity 8.254 0.021

[0133] EXAMPLE 10: Figure- 12 presents the SEM-EDS images of the as-synthesized CSCC-WI. The SEM micrograph reveals distinct morphological features, where brighter, more compact, and aggregated particles are identified as Ni catalysts (Fig. 12a, Spectrum 1), while the more granular regions correspond to the CaO-based sorbent (Fig. 12a, Spectrum 2). The EDS elemental mapping (Fig. 12b) further supports these observations, clearly distinguishing the distribution of key elements. Elemental Ca is predominantly located in the granular regions, confirming the presence of the CaO-based sorbent, whereas elemental Ni is concentrated in the compact zones, indicating well-dispersed Ni particles within the matrix. This distribution suggests effective synthesis of the CSCC, with Ni and CaO phases well integrated to support both catalytic activity and CO2 sorption in the SESMR process.

[0134] Figure- 13 presents TEM images of CSCC-WI and CSCC-WI-CCS after undergoing 25 SESMR cycles. For CSCC-WI, the average particle size ranges between 45-70 nm, indicating minimal sintering and agglomeration even after repeated reaction-regeneration cycles. This observation suggests that CSCC-WI maintains excellent structural stability, which is critical for sustained catalytic activity and CO2 sorption performance over multiple cycles. In contrast, CSCC-WI-CCS exhibits a substantial increase in NiO particle size, ranging from 100 to 700 nm, signifying extensive sintering and agglomeration during SESMR cycles. The pronouncedP_W0100790

[0135] particle growth in CSCC-WI-CCS indicates weaker metal-support interactions, which compromise structural integrity and reduce the catalyst’s long-term stability.

[0136] In summary, present invention represents a significant advancement in the realm of CO2 sorbent materials and H2 production technologies, fostering efficient CO2 capture and high-purity H2 production. The utilization of biowaste-derived CO2 sorbents in the synthesis of dualfunctional materials, which exhibit both catalytic and CO2 sorption capacities within a single grain, introduces new dimensions to sustainable energy processes, with potential applications across diverse industrial and environmental domains, introduces new dimensions to sustainable energy processes. The present invention holds potential applications across diverse industrial and environmental domains.

[0137] ADVANTAGES OF THE INVENTION:

[0138] a) The present invention pertains to a method for synthesizing a CO2 sorbent material derived from biowastes, specifically including snail shells, river shells, eggshells, and seashells. b) CO2 sorbent material derived from snail shells exhibits a significantly higher CO2 uptake compared to commercially available CaO thereby demonstrating superior performance. c) CO2 sorbent material is further employed in the synthesis of a novel dual-functional material comprising a combined sorbent-catalyst composition (CSCC), which incorporates the biowaste- derived CO2 sorbent in combination with nickel (Ni)-based catalyst. d) Combined sorbent-catalyst composition (CSCC) suitable for high purity Blue H2 production through sorption enhanced steam methane reforming.

Claims

P_W0100790We Claim:

1. A dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) represented by the formula xNiyCaOzS, wherein:(a) x is a catalyst (Ni) fraction and is in the range of 15% to 18% by weight;(b) y is a sorbent (CaO) fraction and is in the range of 30% to 50% by weight;(c) z is a support material (S) fraction selected from a group consisting of Ca AluOss, AI2O3, or CaZrO3, and is in the range of 55% to 32% by weight.

2. The dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 1, wherein the catalyst (Ni) fraction selected from nickel nitrate or nickel acetate.

3. The dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 1, wherein the sorbent (CaO) fraction selected from snail shells, seashells, or river shells.

4. The dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 1, wherein the support material (S) fraction Ca Al 14O33 is derived from aluminum nitrate and snail shells, seashells, or river shells.

5. The dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 1, wherein the support material (S) fraction CaZrOs is derived from zirconium nitrate and snail shells, seashells, or river shells.

6. A process for preparation of the dual-functional material (DFM) with scombined sorbent catalyst composition (CSCC) as claimed in claim 1 comprising the steps of:a) calcining snail shell, seashell or river shell powder to obtain CaO;b) preparing the sorbent-support material by dissolving aluminum nitrate or zirconium nitrate in distilled water (10-20 ml) followed by adding the CaO as obtained in step (a) and stirring the solution mixture, then drying and calcining to obtain resulting slurry; c) dissolving nickel nitrate or nickel acetate in distilled water (10-20 ml) to form a precursor solution;d) impregnating the calcined sorbent-support material as obtained in step (b) with the nickel precursor solution as obtained in step (c) and stirring the solution mixture; e) drying the impregnated material and then calcining the mixture to obtain dualfunctional material (DFM) with combined sorbent catalyst composition (CSCC).

7. The process for preparation of the dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 6, wherein the calcination in step (b) andP_W0100790(e) carried out at a temperature in the range of 725°C to 925°C for a period in the range of 4 to 8 hours.

8. The process for preparation of the dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 6, wherein the stirring in step (b) and (d) is carried at a temperature in the range of 80°C to 120°C for a period in the range of 2 to 4 hours.

9. The process for preparation of the dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 6, wherein the drying in step (b) and (e) is carried at a temperature in the range of 100°C to 120°C for a period in the range of 12 to 16 hours.

10. The process for preparation of the dual-functional material (DFM) with combined sorbent catalyst composition (CSCC) as claimed in claim 6, wherein the particle size of CaO in range of 30-100 micrometer.

Images