Al2O3 Catalyst Research Articles

CO2 methanation over NiO catalysts supported on CaO–Al2O3: Effect of CaO:Al2O3 molar ratio and nickel loading

This study conducted the CO2 methanation reaction over the nickel-based catalysts supported on CaO.Al2O3 with different CaO/Al2O3 molar ratios. The catalyst support was synthesized with the mechanochemical method, and the influence of nickel loading was investigated on the selected catalyst support with an appropriate CaO/Al2O3 molar ratio. According to the results, incorporating Al2O3 into the CaO increased the BET area from 5 to 196 m2 g−1. Also, the SBET of the calcined catalysts decreased with the augmentation of nickel oxide percentage from 5 to 15 wt% due to the pore blocking of the support after metal addition. Moreover, the activity of catalysts enhanced with the increment of CaO/Al2O3 molar ratio and NiO percentage, ascribed to the improvement in the reducibility of the catalysts. However, the excessive addition of CaO and nickel oxide reduced the CO2 conversion because of a significant decrease in surface area. Therefore, 10 wt% NiO/CaO.2Al2O3 catalyst possessed superior CO2 conversion (79.1%) and CH4 selectivity (98.1%) in CO2 methanation reaction at 450 °C, H2/CO2 = 4 and GHSV = 18,000 ml h−1.g−1cat. The selected sample illustrated great stability for 11 h without any remarkable change in its initial catalytic activity. The impact of GHSV on the catalytic performance of the selected catalyst was evaluated, and the outcomes exhibited that decrement in GHSV value enhanced CO2 conversion. With the increment of feed ratio (H2/CO2) from 2 to 5, CO2 conversion reached 93.3%, ascribed to the existence of adequate hydrogen to react with CO2.

Pd sub-nanolayer on Au core for enhanced catalytic hydrogenation reduction of oxyanions pollutants: Synergistic effect of Pd and Au

Oxyanion pollutants in industrial wasterwater, such as (Cr(VI)), BrO3− (Br(V)) and SeO32− (Se(IV)) have detrimental or toxic effects on individual health when their concentrations accumulated to a certain level. The conversion of these oxyanions into harmless/industrial-valuable products or removal from wastewater is of significance. Herein, we designed Pd sub-nanolayer on Au core catalysts supported on Al2O3 (sub-Pd-Au/Al2O3) for highly effective catalytic hydrogenation reduction of oxyanions under ambient conditions. The sub-Pd(0.049)-Au(0.927)/Al2O3 catalyst exhibited the highest catalytic activity and TOF value for Cr(VI), Br(V) and Se(IV) reduction, respectively, by optimizing the Pd loading amount. The synergistic effect between Pd sub-nanolayer and Au core enhanced catalytic activity by regulating the Pd dispersion and site property, according to thorough characterizations that included high-angle annular dark-field transmission electron microscopy (HAADF-TEM) image, in-situ CO-IR adsorption, CO chemisorption, and X-ray photoelectron spectroscopy (XPS). This work might provide some new lights on design of highly efficient catalysts for the elimination of oxyanion pollutants.

Sorption-enhanced steam reforming of toluene using multifunctional perovskite phase transition sorbents in a chemical looping scheme

Sorption-enhanced steam reforming (SESR) of toluene (SESRT) using catalytic CO2 sorbents is a promising route to convert the aromatic tar byproducts formed in lignocellulosic biomass gasification into hydrogen (H2) or H2-rich syngas. Commonly used sorbents such as CaO are effective in capturing CO2 initially but are prone to lose their sorption capacity over repeated cycles due to sintering at high temperatures. Herein, we present a demonstration of SESRT using A- and B-site doped Sr1−x A’ x Fe1−y B’ y O3−δ (A’ = Ba, Ca; B’ = Co) perovskites in a chemical looping scheme. We found that surface impregnation of 5–10 mol% Ni on the perovskite was effective in improving toluene conversion. However, upon cycling, the impregnated Ni tends to migrate into the bulk and lose activity. This prompted the adoption of a dual bed configuration using a pre-bed of NiO/γ–Al2O3 catalyst upstream of the sorbent. A comparison is made between isothermal operation and a more traditional temperature-swing mode, where for the latter, an average sorption capacity of ∼38% was witnessed over five SESR cycles with H2-rich product syngas evidenced by a ratio of H2: CO x > 4.0. XRD analysis of fresh and cycled samples of Sr0.25Ba0.75Fe0.375Co0.625O3-δ reveal that this material is an effective phase transition sorbent—capable of cyclically capturing and releasing CO2 without irreversible phase changes occurring.

Enhanced Catalytic Ozonation by Mn-Ce Oxide-Loaded Al2O3 Catalyst for Ciprofloxacin Degradation.

Catalytic ozonation is an effective and promising advanced oxidation technology for organic pollutant removal. Herein, CexMn1-xO2 metal oxides loaded on Al2O3 catalysts (Mn-Ce/Al2O3) were synthesized for catalytic ozonation of the wastewater containing ciprofloxacin. The morphology, crystal structure, and specific surface area of the prepared catalyst were characterized. The characteristics of the Mn-Ce/Al2O3 catalyst revealed that the loaded MnO2 could interfere with the formed CeO2 crystals and then produced complex CexMn1-xO2 oxides. Compared with an ozone-alone system (47.4%), the ciprofloxacin degradation efficiency in the Mn-Ce/Al2O3 catalytic ozonation system elevated to 85.1% within 60 min. The ciprofloxacin degradation kinetic rate over the Mn-Ce/Al2O3 catalyst is 3.0 times that of the ozone-alone system. The synergetic corporation of redox pairs between Mn(III)/Mn(IV) and Ce(III)/Ce(IV) in the Mn-Ce/Al2O3 catalyst could accelerate ozone decomposition to generate active oxygen species and further significantly improve the mineralization efficiency of ciprofloxacin. The work demonstrates the great potential of developing dual-site ozone catalysts for advanced treatment of wastewater.

Insight into the true role of hydrogen‑carbonate species in CO oxidation over Pd/Al2O3 catalyst using SSITKA-transmission IR technique

The powerful combination of steady state isotopic transient kinetic analysis (SSITKA) and operando infrared spectroscopy (IR) was applied to study the CO oxidation reaction on Pd-supported Al2O3 catalyst at low temperature. The aim was to reveal the true role of hydrogen‑carbonate species in the reaction mechanism. The SSITKA-IR experiments, conducted in presence and absence of CO2 in the gas feed, have confirmed that hydrogen‑carbonate species behave as spectator species in the reaction. Its formation was due to re-adsorption of the CO2 product itself on the alumina surface as confirmed by the direct 12CO2/13CO2 exchange observed on the bare support.

Combined steam and dry reforming of methanol over Ni-M/Ce–Al2O3 (M=Fe, Cu, and Zn) catalysts to syngas formation

In the present work, the influences of different transition metals (Fe, Cu, and Zn) addition to Ni/Ce–Al2O3 catalyst on combined steam and dry reforming of methanol (CSDRM) reaction were evaluated in the temperature range of 500 ºC-900 °C, to achieve the higher conversion and H2 yield following by minimum coke formation on the catalyst surface. The fresh and spent catalysts were characterized via X-ray diffraction (XRD), thermal gravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometer (ICP-AES), temperature programmed oxidation (TPO), N2 adsorption/desorption and temperature programmed reduction (TPR). Their results presented that the addition of these transition metals had a little effect on the crystallinity, surface area, pore volume and mean pore size. However, thermal stability, coke deposition coke amount, reducibility and catalytic activity were improved. The methanol conversion was approximately fixed up to 50 h initial on stream with no obvious deactivation for Ni/Ce–Al2O3 catalyst, while this time was 55 h for the modified catalyst with transition metals (Cu, Fe, and Zn). The maximum methanol and CO2 conversions and anti-coke deposition ability were obtained from Ni–Zn/Ce–Al2O3 which was remarkably related to synergism between Ni and Zn, also the larger reducibility. However, the maximum value of H2 yield was 85.2% at 900 °C over Ni–Cu/Ce–Al2O3 catalyst. Ni–Zn/Ce–Al2O3 catalyst in the CSDRM reaction produced syngas with an H2/CO ratio of 2.06, suggesting to a suitable feed for Fischer-Tropsch synthesis.

Efficient Synthesis of Solketal from Glycerol and Acetone Catalyzed by FeCl3 /γ‐Al2O3**

AbstractThe porous spherical alumina (γ‐Al2O3) as catalyst support was prepared by sol‐gel method, and FeCl3/γ‐Al2O3 materials were prepared by impregnation method. The FeCl3/γ‐Al2O3 materials were used as catalyst in the Solketal production process by acetalization of acetone and glycerol, showing considerable catalytic performance. When the molar ratio of glycerol and acetone was 1 : 10, 0.2 mol% FeCl3/γ‐Al2O3 was used as the catalyst, and the reaction was carried out at 25 °C for 30 min, the conversion of glycerol was 99.89 %, the selectivity of Solketal was 98.36 %, and the yield of Solketal reached 98.25 %. The mechanism is due to the spherical γ‐Al2O3 support has high thermal stability, large specific surface area, and rich pore structure, encouraging abundant active sites and high catalytic activity of FeCl3 for the acetalization reaction. Thereafter, the experimental results prove that the prepared FeCl3/γ‐Al2O3 catalyst can be easily recovered and reused many times, indicating its great value for large‐scale research and application in the future.

Mass Spectrometric Evaluation of the Catalytic Deoxygenation of Soluble Organic Matter in Xiaolongtan Lignite

The organic matter in Xiaolongtan lignite was thermally dissolved by cyclohexane, methanol and isopropanol (2-propanol) in sequence to obtain thermal dissolution (TD) extracts. Co-Mo/γ-Al2O3 was used as the catalyst for the catalytic hydrogenation of TD extracts to remove oxygen. Both TD extracts and the corresponding catalytic products were analyzed by the combination of gas chromatography/mass spectrometry (GC/MS) and Orbitrap MS to reveal more molecular details. GC/MS analysis shows that cyclohexane can extract low polar organic matter in coal, while methanol and isopropanol as nucleophilic reagents can break C-O bonds in coal, thus removing oxygen. Catalyst can trigger the fracture of alkyl chains and the activation of H2, thus promoting the removal of oxygen atom and the generation of aromatics. Double bond equivalent (DBE) value and carbon number (CN) were obtained through Orbitrap MS data. The decrease of both DBE and CN after catalytic conversion indicates the breaking of bridged bonds. The introduction of various MS systems provides an effective analytical tool for studying the catalytic deoxidation of lignite, thereby guiding the conversion of lignite to clean liquid fuels and high value-added chemicals. Co-Mo/ γ- Al2O3 catalysts activates H2 to H⋯H, which further splits into H+ and H−. H⋯H deoxygenates by hydrogenating C=C bond, attacking C-O bond or directly attacking oxygen atom. H+ will preferentially attack oxygen atom with high electronegativity, and break Cal-O bridge bond to achieve deoxygenation, thus reducing the relative abundance of oxygen containing compounds.

Fabrication and catalytic evaluation of Ni/CaO–Al2O3 in glycerol steam reforming: Effect of Ni loading

The present study aims to assess the catalytic activity of the Ni/CaO–Al2O3 catalysts with different Ni loadings (2.5, 5, 10, 15, and 20 wt %) for H2 generation via the glycerol steam reforming (GSR). The support was prepared by the mechanochemical method, and then the various contents of nickel were impregnated on the support surface. The synthesized samples were characterized by BET, XRD, H2- TPR, CO2-TPD, TPO, FTIR, and SEM analyses. High stable catalytic activity was reported for the prepared catalysts. Among the investigated catalysts, 15%Ni/CaO–Al2O3 with the highest reducibility, proper BET area (96.6 m2 g−1), and suitable basicity possessed the highest catalytic performance with glycerol conversion of 99.4% at 700 °C. All the samples had high stability after 5 h, and the 15%Ni/CaO–Al2O3 showed 97.5% glycerol conversion at 550 °C without any decline in glycerol conversion durin 15 h time on stream. It was also found that glycerol conversion decreased with the increase in gas hourly space velocity and calcination temperature.

Ni-based catalyst supported on ordered mesoporous Al2O3 for dry CH4 reforming: Effect of the pore structure

Ni-based catalysts supported on ordered mesoporous Al2O3 with 2-D hexagonal and 3-D cubic pore structures are synthesized via evaporation-induced self-assembly for catalyzing dry CH4 reforming to produce syngas. The Ni–Al2O3 catalysts with 3-D pore structure exhibit higher activity in terms of CH4 and CO2 conversions than those with 2-D pore symmetry, due to the better mass transfer of the 3-D interconnected pore structure for the accessibility of Ni0 active sites. And a higher Ni content slightly promotes catalytic activity, owing to more exposed active sites. However, a higher Ni content causes more severe carbon deposition during long-term reaction. During the long-term stability tests, the catalysts with 2.5 wt% Ni maintain the highest stability regardless of the pore structure, and the catalyst with 3-D pore structure is more advantageous to both activity and stability. Meanwhile, the catalyst with 2.5 wt% Ni and 3-D pore structure shows the lowest carbon deposition.

Single‐Atom Fe Catalyst for Catalytic Ethane Dehydrogenation to Ethylene

AbstractThe single atom catalysts (SACs) show unique catalytic performance in heterogeneous reactions owing to unsaturated coordination sites and high metal atom dispersion. Herein, a simple wet impregnation method was utilized to synthetize of Fe−Al2O3 catalysts. The Fourier transformation infrared spectroscopy (FTIR) revealed that abundant OH group attached to the support (Al2O3) surface facilitating formation of isolated Fe single atom. High resolution transmission electron microscope (HR‐TEM) and extended X‐ray absorption fine structure (EXAFS) confirmed the Fe single atom architecture. Fe−Al2O3 (4.5 wt %) performed enhanced stability and activity on ethane dehydrogenation reaction.

Enhancing Kinetics of Carbonyl Sulfide Hydrolysis Using Pt-Supported Al2O3 Catalysts: First-Principles-Informed Energetic Span Analysis

Catalytic hydrolysis is considered an effective strategy for treating carbonyl sulfide (COS)─a toxic sulfur-containing gas that causes problems to the environment and petrochemical industries. Al2O3-based materials are commonly used as catalysts for COS hydrolysis owing to their stability and cost effectiveness. However, they still suffer from sulfur poisoning leading to partial COS conversion after long time use. To improve their catalytic performances, herein, we computationally designed and studied the catalytic activity of the Pt-supported Al2O3 catalysts by means of density functional calculations. We mechanistically explored the COS hydrolysis on both bare and Pt-decorated surfaces to reveal the role of Pt catalysts in the reaction kinetics. We find that bare Al2O3 suffers from difficult C–S bond breaking as its barrier is relatively high. Pt facilitates C–S bond breaking where its barrier is reduced by more than half (1.34 to 0.60 eV). However, the Pt–Al2O3 catalyst could encounter sulfur poisoning as the sulfur-containing intermediates are rather stable. Such issues could be remedied by increasing the operating temperature to destabilize the intermediates and promote product desorption. The energetic span models reveal that the important states of bare and Pt–Al2O3 are indeed C–S bond breaking and product desorption corresponding to an energy span of 2.72 and 1.67 eV at 773 K, respectively─suggesting that Pt dramatically enhances the catalytic activity of Al2O3-based catalysts toward COS hydrolysis. The suggested operating temperatures are above 673 K to avoid sulfur poisoning. Our findings will be useful for the development of more efficient Al2O3-based catalysts for treating COS.

Ethanol Coupling Reactions over MgO-Al2O3 Mixed Oxide-Based Catalysts for Producing Biofuel Additives.

Catalytic conversion of ethanol to 1-butanol was studied over MgO-Al2O3 mixed oxide-based catalysts. Relationships between acid-base and catalytic properties and the effect of active metal on the hydrogen transfer reaction steps were investigated. The acid-base properties were studied by temperature-programmed desorption of CO2 and NH3 and by the FT-IR spectroscopic examination of adsorbed pyridine. Dispersion of the metal promoter (Pd, Pt, Ru, Ni) was determined by CO pulse chemisorption. The ethanol coupling reaction was studied using a flow-through microreactor system, He or H2 carrier gas, WHSV = 1 gEtOH·gcat.-1·h-1, at 21 bar, and 200-350 °C. Formation and transformation of surface species under catalytic conditions were studied by DRIFT spectroscopy. The highest butanol selectivity and yield was observed when the MgO-Al2O3 catalyst contained a relatively high amount of strong-base and medium-strong Lewis acid sites. The presence of metal improved the activity both in He and H2; however, the butanol selectivity significantly decreased at temperatures ≥ 300 °C due to acceleration of undesired side reactions. DRIFT spectroscopic results showed that the active metal promoted H-transfer from H2 over the narrow temperature range of 200-250 °C, where the equilibrium allowed significant concentrations of both dehydrogenated and hydrogenated products.

Effect of ceria content in Ni–Ce–Al catalyst on catalytic performance and carbon/coke formation in dry reforming of CH4

In this study, to enhance the catalytic activity and minimize the carbon/coke formation, cerium incorporated alumina-supported new Ni–Ce–Al catalysts were investigated in dry reforming of biogas. Ni–Ce–Al catalysts were synthesized by the modified one-pot sol-gel method in an inert environment. To determine the effect of the Ce/Al ratio on physicochemical properties of catalysts and their activity, Ni (5 wt %) catalysts with different Ce/Al ratios (0/1, 1/2, 1/1, 2/1 b y wt.) were tested in a fixed-bed flow reactor using an equimolar ratio of CH4/CO2/Ar gas mixture. To explain the correlation between catalytic activity and catalyst properties, characterization studies were carried out by using N2 adsorption-desorption isotherms, XPS, XRD, SEM-EDS, TEM, ICP-OES, DRIFT, O2-TPO and TGA methods before and after activity tests. XRD analysis showed that both CeO2 and γ-Al2O3 crystalline phases with metallic Ni having different peak intensities were separately formed in all the catalysts. Among the catalysts of different Ce/Al ratios, the Ni–1Ce–1Al catalyst containing equal amounts of Al and Ce has the smallest CeO2 crystallite size. This catalyst also has the highest pore diameter and volume. XPS analysis showed that Ce incorporation into the Ni-based Al2O3 catalyst decreased the NiAl2O4 formation. DRIFT analysis indicated that the addition of ceria into the support material decreased the Lewis acidity of alumina. During 25-h long-term activity test, the conversions of CH4 and CO2 obtained with the catalyst Ni–1Ce–1Al (Ce/Al ratio is 1/1) were approximately the same and averaged 76% and 85%, respectively. This behavior of the catalyst indicates its high stability. TGA, XRD and SEM analyzes performed with the used Ni–1Ce–1Al and Ni–Al catalysts show very little carbon formation in the catalyst containing equal weights of Ce and Al compared to the catalyst without Ce. This result shows that the addition of cerium to the catalyst structure prevents carbon deposition due to its special oxygen mobility. This study showed that the crystallite size of CeO2 in the catalyst structure strongly influences preventing carbon accumulation in the dry reforming reaction.

Synthesis and evaluation of lanthana modified Cu-based catalysts for CO2 hydrogenation to value added products

This study deals with the development and evaluation of lanthana promoted Cu-based catalysts for CO2 hydrogenation reaction. The samples were prepared using solution combustion synthesis method. The study demonstrates that the incorporation of 3wt% lanthana (La2O3) into a CuO/ZnO/Al2O3 results in a catalyst with exceptionally high catalytic performance. The synthesized catalysts were thoroughly characterized by various analytical tools such as HRTEM, XRD, XPS, H2-TPR, H2-TPD and CO2-TPD. The catalysts were assessed for CO2 hydrogenation reaction in a high-pressure fixed-bed reactor. The La2O3 promoted catalyst with a composition of 0.6Cu/0.3ZnO/0.03La2O3/0.07Al2O3 was selective to methanol (60%) even at an operating temperature as high as 325 °C and an operating pressure of 85 bars. Under similar operating conditions, the 0.6Cu/0.3ZnO/0.03La2O3/0.07Al2O3 catalyst exhibited better CO2 conversion, MeOH selectivity and MeOH production as compared to unpromoted catalyst, 0.6Cu/0.3ZnO/0.1Al2O3. At reaction conditions of T = 300 °C, P = 85 bar, and GHSV=55,000h-1, the lanthana promoted catalyst showed a CO2 conversion and methanol selectivity of 20% and 65%, respectively; while the production rates of carbon monoxide and methanol were 0.55 g/g-cat h−1 and 0.79 g/g-cat h−1. The high catalytic efficiency is attributed to the formation of oxygen vacancies and/or generation of defects in the catalyst surface, smaller Cu nanoparticles with LaOx, and a comparable larger number of mild basic sites. Similar catalyst prepared by wet impregnation method performed poorly, thus highlighting the role of combustion synthesis and the effect of temperature in forming unique metal oxide phases responsible for higher catalytic performance.

Feasibility Assessment on Remanufacturing of Ni–Mo/γ–Al2O3 Catalyst for Residue Hydrodesulfurization

Residue hydrodesulfurization (RHDS) is a critical process in the petroleum refining industry for removing sulfur compounds from heavy residual oils. However, catalysts used in RHDS can easily be deactivated by numerous factors, leading to reduced process efficiency and economic benefits. The remanufacturing of spent catalysts can be a useful strategy for extending the lifespan of catalysts, reducing waste, and improving process sustainability. This paper proposes an effective catalyst remanufacturing process for commercial RHDS catalysts. In detail, sequential unit processes including oil washing (OW), complete incineration (CI), and acid leaching (AL) were conducted to remanufacture the spent RHDS catalysts. We also highlight some of the key challenges in remanufacturing catalysts, such as the key factors involved in catalyst deactivation. Finally, we provide future perspectives on the development of an effective catalyst remanufacturing process for RHDS, with the goal of improving the efficiency, sustainability, and competitiveness of the petroleum refining industry.

Elucidation of puzzling questions regarding the CrOx/Al2O3 catalyst I. X-ray absorption spectroscopy aided identification of the nature of the chromium oxide species in the CrOx/Al2O3 dehydrogenation catalyst system

The CATOFIN© process produces propylene from propane using a CrOx /Al2O3 catalyst. Despite its use, there are still uncertainties surrounding the nature of Cr species formed during synthesis, regeneration, and aging. It has been observed that ppm levels of Cr2O3 can be oxidized to Cr(VI) in air; however, when Cr2O3 is in direct contact with Al2O3, Cr(VI) formation increased more than 100-fold. To confirm physical contact between Cr2O3 and Al2O3 results in increased Cr(VI) formation, Cr2O3 and Cr2O3/Al2O3 samples were synthesized, calcined, and characterized. Catalytic activity measurements confirm propylene selectivity inversely tracks with Cr(VI). Wet chemical titration and X-ray absorption spectroscopy (XAS) quantified and determined the structure of the Cr(VI) species. FEFF X-ray absorption near edge structure simulations determined the potential sensitivity of the XAS to the presence of Al3+/Cr3+ neighboring atoms. XAS correlated to FEFF simulations suggested that Al3+xCr3+2−xCr6+3O12 comprises a significant fraction of the Cr(VI) species formed.

Unravelling the role of metal-metal oxide interfaces of Cu/ZnO/ZrO2/Al2O3 catalyst for methanol synthesis from CO2: Insights from experiments and DFT-based microkinetic modeling

Cu/ZnO/ZrO2/Al2O3 catalysts are widely explored for CO2 conversion to methanol due to their higher activity and stability. However, mechanistic understanding of the performance of such catalysts is lacking due to ambiguity on the actual active sites. This study focuses on unraveling the nature of different interfaces on Cu/ZnO/ZrO2/Al2O3 catalyst by coupling experiments, Density Functional Theory (DFT) simulations and a DFT-based reactor scale multi-site microkinetic model. Although DFT calculations suggested the ZrO2/Cu interface to be the CO2 adsorption site, the validated microkinetic model predicted the ZnO/Cu interface to be the crucial reaction center. Reaction pathway analysis showed that methanol is produced through the formate pathway near the reactor entrance, whereas, the carboxyl pathway dominates in the latter zones, emphasizing the occurrence of both CO2 and CO hydrogenation. This deeper understanding of the reaction behavior of such multicomponent catalysts will aid in designing better catalysts and optimizing reaction conditions and systems.

Kinetics of oxidative bio-ethanol reforming over bimetallic structured catalysts

The core of this work is a comprehensive investigation of ethanol oxidative reforming kinetics over a Pt–Ni/CeO2–Al2O3 catalyst in the presence of fuel grade bioethanol, which has been very rarely investigated in the past. The developed kinetic model also included the formation of solid carbon. The results show that the reaction scheme involving ethylene and acetaldehyde formation from ethanol, their subsequent decomposition, methane oxidation as well as steam reforming and water gas shift reaction is able to assure a satisfactory fitting of the experimental data. Moreover, the above formulation, deposited on a porous support (Ni–Fe foam), was employed for a very long stability test (almost 400 h) and subjected to several oxidation-reduction cycles: at 600 °C, after 170 h of time-on-stream, a stable ethanol conversion of 95% and hydrogen yield of 35% were recorded, with near-zero carbon emission during its thermochemical conversion for energy generation.

Integration of the PEMFC with a hydrogen production device adopting sodium borohydride and metal cobalt catalyst

Hydrolysis technology that releases hydrogen from chemical hydrogen storage materials is a method to produce hydrogen. Hydrogen storage has excellent development potential and is also one of the sources of large amounts of hydrogen. A sodium borohydride hydrogen production experiment was carried out based on steam hydrolysis technology. The system reaction tank is divided into a water-carrying bed and a catalyst bed. A mixed aqueous solution with a concentration of 1 wt% sodium hydroxide (NaOH) + 10 wt% sodium borohydride (NaBH4) was used for the hydrogen production reaction test. These experiments determined the appropriate aqueous solution and water vapor combination, and optimal parameters for hydrogen production. The hydrogen production catalyst powder, blend ratio, different steel ball ratios, and ball milling time at the steam hydrogen production end will all affect the powder's fineness and hydrogen production stability. Under catalyst temperature control, the by-products solidify at a specific temperature, which affects the gas passage and causes blockage. Increasing the hydrogen production in an aqueous solution requires a Co2+/Al2O3 catalyst, or a temperature control method to catalyze hydrogen production to obtain stable hydrogen production suitable for emergencies without hydrogen storage containers. This experiment built a hydrogen production system combined with a fuel cell for power generation testing. The test process and results indicate whether the aqueous solution and steam technology can be an effective solution when the hydrolysis hydrogen production technology is matched.