Production of metal-free catalyst from defatted spent coffee ground for hydrogen generation by sodium borohyride methanolysis

In the present study, defatted spent coffee ground (DSCG) treated with different acids was used as a metal-free catalyst for the first time. The aim of undertaken work is to demonstrate that DSCG can be used as a green catalyst to produce hydrogen through methanolysis of sodium borohydride. To produce hydrogen by the sodium borohydride methanolysis (NaBH₄), DSCG was pretreated with different acids (HNO₃, CH₃COOH, HCl). According to the superior acid performance, acetic acid was selected and then different concentrations of the chosen acid were evaluated (1M, 3M, 5M, and 7M). Subsewuently, different temperatures (200, 300, 400 and 500 °C) and burning times (30, 45, 60 and 90 min) for the optimization of DSCG-catalyst were tested. The experiments with the use of CH₃COOH treated DSCG-catalyst reveal that the optimal acid concentration was 1M CH₃COOH and the burning temperatures and time were 300 °C and 60 min, respectively. FTIR, SEM, ICP-MS and CHNS elemental analysis were carried out for a through characterization of the catalyst samples. In this study, the experiments were carried out with 10 ml methanol solution contained 0.025 g NaBH₄ with 0.1 g catalyst at 30 °C unless otherwise stated. The effect of NaBH₄ concentration was investigated with use of 1%, 2.5%, 5%, and 7.5% NaBH₄, while the influence of catalyst concentration was discovered with the use of 0.05, 0.1, 0.15, and 0.25 g catalyst. Different temperatures were chosen (30, 40, 50 and 60 °C) to explore the hydrogen production performance of the catalyst. In addition, the maximum hydrogen production rate through methanolysis reaction of NaBH₄ by this catalyst was found to be 3171.4 mL min⁻¹gcat⁻¹. Also, the activation energy was determined to be 25.23 kJ mol⁻¹.     

Synthesis of novel biocatalyst from organic waste protonated with acid treatment for hydrogen production

In this research study, orange peel-based biocatalysts developed from different acid protonation were used as a metal-free catalyst for hydrogen production from sodium borohydride (NaBH₄). In order to prepare the orange peel-based biocatalyst with higher catalytic activity, experiments were conducted with pure orange peel, different acid molar concentrations, and calcination temperatures. The physical morphology, surface texture, and chemical interaction were thoroughly analyzed by XRD, FTIR Raman, FESEM, BET, and TGA. As a result of the experiment, it was determined that the highly acid-treated biocatalyst (40% H₃PO₄, 40% H₂SO₄, 40% HCl) and calcinated at 450 °C for 1 h had higher catalytic activity. As a result, bio-hydrogen production at 35 °C and 70 °C methanolysis with 3% NaBH₄ catalyzed by a mixture of acid-treated catalysts were found as 46,213 and 63,842 ml min⁻¹g.cat⁻¹, respectively. However, with the increase of molar concentration of biocatalyst with 40% individual acid prolonged samples, the HGR rates will not have a satisfactory value in comparison with the 40% mixture of the acid-treated catalyst due to less number of active sites.     

A novel hazelnutt bagasse based activated carbon as sodium borohydride methanolysis and electrooxidation catalyst

In this study, activated carbon is produced from defatted hazelnut bagasse at different activation conditions. The catalytic activities of activated carbons are evaluated for NaBH₄ methanolysis and electrooxidation. These materials are characterized by N₂ adsorption-desorption, FTIR, SEM-EDS and XPS and results show that these materials are prepared successfully. N₂ adsorption-desorption results reveal that activated carbon (FH3-500) has the highest BET surface area as 548 m²/g, total pore volume as 0.367 cm³/g and micropore volume as 0.205 cm³/g. On the orher hand, as a result of hydrogen production studies, FH3-500 activated carbon catalyst has the highest initial hydrogen production rate compared to other materials. At 50 °C, this metal-free activated carbon catalyst has a high initial hydrogen production rate of 13591.20 mL/min.g_cat, which is higher than literature values. Sodium borohydride electrooxidation measurements reveal that FH2-500 also has the highest electrocatalytic activity and stability. Hazelnut pulp-based activated carbons are firstly used as a metal-free catalyst in the methanolysis and electrooxidation of sodium borohydride, and its catalytic activity is good as a metal-free catalyst. The results show that the hazelnut pulp-based activated carbon catalyst is promising as a metal-free catalyst for the methanolysis and electrooxidation of sodium borohydride.     

Metal-free hybrid composite particles with phosphorus and oxygen-doped graphitic carbon nitride dispersed on kaolin for catalytic activity toward efficient hydrogen release

Here, hybrid kaolin-g-C₃N₄ heterostructure particles were fabricated by calcination in the first step, followed by hydrothermal phosphoric acid activation in the second step, and phosphorus (P) and oxygen (O) doped kaolin-g-C₃N₄ metal-free catalyst was synthesized. This hybrid metal-free catalyst was used for the first time for the production of effective hydrogen (H₂) from sodium borohydride (NaBH₄) methanolysis. The hydrogen generation rate (HGR) value of 5500 ml min⁻¹g⁻¹ was obtained with the P and O doped kaolin-g-C₃N₄ catalyst. The activation energy (Ea) of 31.90 kJ mol⁻¹ by P and O doped kaolin-g-C₃N₄ for the production of H₂ was obtained. The kaolin-g-C₃N₄ and P and O doped kaolin-g-C₃N₄ metal-free catalysts were systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Based on the results obtained, the mechanism of P and O-doped kaolin-g-C₃N₄ catalyst on H₂ production from NaBH₄ methanolysis was also proposed.     

Metal-free catalysts with phosphorus and oxygen doped on carbon-based on Chlorella Vulgaris microalgae for hydrogen generation via sodium borohydride methanolysis reaction

Metal-free catalysts (C–KOH–P) containing phosphorus (P) and oxygen (O) prepared by the modification with phosphoric acid (H₃PO₄) of activated carbon (C–KOH) obtained by activation of Chlorella Vulgaris microalgae with potassium hydroxide (KOH) were investigated for the hydrogen (H₂) generation reaction from methanolysis of sodium borohydride (NaBH₄). Elemental analysis, XRD, FTIR, ICP-MS, and nitrogen adsorption were used to analyze the characteristics of metal-free catalysts. The results showed that groups containing O and P were attached to the carbon sample. In the study, the hydrogen production rates (HGR) obtained with metal-free C–KOH and C–KOH–P catalysts were 3250 and 10,263 mL/min/g, respectively. These HGR values are better than most values obtained for many catalysts presented in the literature. Besides, relatively low activation energy (Ea) of 27.9 kJ/mol was obtained for this metal-free catalyst. The C–KOH–P metal-free catalyst showed ideal reusability with 100% conversion and a partial reduction in the H₂ production studies of NaBH₄ methanolysis after five consecutive uses.     

Phosphorus and oxygen doped carbon-based on Spirulina microalgae as efficient metal-free catalysts to obtain H2 from methanolysis of NaBH4

Metal-free catalysts (SP–KOH–P) doped phosphorus and oxygen as a result of modification with H₃PO₄ to the surface of the activated carbon sample (SP–KOH) obtained by activation of KOH with Spirulina microalgae were used to obtain hydrogen (H₂) from methanolysis of NaBH₄. The characteristic structure of SP-KOH-P and SP-KOH metal-free catalysts were examined by XRD, TEM, elemental analysis, FTIR, and ICP-MS. The effects of the amount of catalyst, NaBH₄ concentration, reusability, and temperature on H₂ production rate from NaBH₄ methanolysis reaction were investigated. The hydrogen production rate (HGR) obtained with 25 mg SP-KOH-P was found to be 19,500 mL min^?1 g^?1. The activation energy (Ea) value of SP-KOH-P metal-free catalyst sample was calculated as 38.79 kJ mol^?1.     

Phosphorus doped carbon nanodots particles based on pomegranate peels for highly active dehydrogenation of sodium borohydride in methanol

Here, the carbon nanodots were successfully synthesized from pomegranate peels (PPCD). This obtained PPCD was treated by a hydrothermal process with phosphoric acid for P doping (P doped PPCD) and used as a metal-free catalyst to obtain hydrogen(H₂) from sodium borohydride (NaBH₄) methanolysis for the first time. The characteristics of the samples obtained by ultraviolet, fluorescence, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Inductively coupled plasma mass spectrometry (ICP-MS) analyses were examined. NaBH₄ concentration effect, temperature effect and catalyst reusability experiments were carried out. Using 10 mg of the catalyst with 2.5% NaBH₄, an HGR value of 13000 mL min^?1g^?1 was obtained. The activation energy (Ea) for the P-doped PPCD catalyst was 30.96 kJ mol^?1.     

Spirulina microalgal strain as efficient a metal-free catalyst to generate hydrogen via methanolysis of sodium borohydride

Metal-free catalyst based on Spirulina platensis microalgae (SPM) is protonated by phosphoric acid (H₃PO₄) treatment (SPM-H₃PO₄). The microalgae sample is then exposed to heating with different temperatures including 200, 300, and 400 °C (SPM-H₃PO₄-H). The modified microalgae sample based on Spirulina platensis as a catalyst is directly used to generate hydrogen via the methanolysis of sodium borohydride (MSB). The activation temperature, activation time, NaBH4 concentration, catalyst amounts, temperature and reusability tests were carried out. The maximum hydrogen production rates (HGR) obtained for SPM-H₃PO₄-H at temperatures of 30 °C and 60 °C were 3975 and 9600 mLmin⁻¹gcat⁻¹, respectively. At the same time, the activation energy(Ea) of 17.78 kJ mol⁻¹ was obtained. Reusability experiments were performed for this microalgae-based metal-free catalyst. XRD, SEM, FTIR, BET, and TEM analyzes were performed for characterization of these metal-free catalyst samples.     

A novel cost-effective catalyst from orange peel waste protonated with phosphoric acid for hydrogen generation from methanolysis of NaBH4

In this study, orange peel (OP), one of the organic wastes, was first used as a metal-free catalyst for the production of hydrogen from sodium boron hydride (NaBH₄). In order to prepare an orange peel catalyst (OP–H₃PO₄-Cat) with the best catalytic activity, experiments were carried out on pure orange peel with different acid types, different burning temperatures and different burning times. As a result of these experiments, it was determined that OP-H₃PO₄-Cat treated with 30% H₃PO₄ and burned at 400 °C for 45 min had the best catalytic activity. The OP-H₃PO₄-Cat material was characterised by several techniques such as FTIR, XRD and SEM. As a result, the hydrogen generation rates (HGR) at 30 °C and 60 °C in the methanolysis reaction of 2.5% NaBH₄ catalysed by OP-H₃PO₄-Cat were found as 45,244 and 61,892 mLmin^?1g.cat^?1, respectively. The activation energy of OP-H₃PO₄-Cat catalyst was calculated as 12.47 kJmol^-1.     

Very efficient dehydrogenation of methanolysis reaction with nitrogen doped Chlorella Vulgaris microalgae carbon as metal-free catalysts

In this study, nitrogen (N) doped metal-free catalysts were obtained as a result of nitric acid (HNO₃) activation of carbon sample (C–KOH–N), which was obtained based on Chlorella Vulgaris microalgae by KOH activation (C–KOH). These catalysts have been effectively used to produce hydrogen (H₂) from the sodium borohydride (NaBH₄) methanolysis reaction. Compared to the C–KOH catalyst, the catalytic activity for C–KOH–N showed a seven-fold improvement. Hydrogen generation rate (HGR) values obtained for the NaBH₄ methanolysis reaction for C–KOH and C–KOH–N metal-free catalysts were 3250 and 20,100 mL min^?1 g^?1. The catalysts were characterized using various analytical techniques such as XPS, XRD, SEM, FTIR, BET, and elemental analysis. This work can provide a new alternative strategy to produce specific heteroatom-doped metal-free carbon catalysts for environmentally friendly conversion to produce H₂ efficiently.     

PDMA cryogel beads as a catalyst for hydrogen generation from NaBH4 alcoholysis

Poly[2-(dimethylamino)ethyl methacrylate] cryogel beads were prepared under cryogenic conditions via free radical polymerization and used as a catalyst in the production hydrogen (H₂) from NaBH₄ by alcoholysis. The efficiency of the catalyst was investigated in the range of 0–40 °C by both methanolysis and ethylene glycolysis reactions, and its reuse was tested. Accordingly, it was observed that the methanolysis reaction was faster than the ethylene glycolysis reaction. When the hydrogen generation rate (HGR) values between 0 and 40 °C were compared, it was concluded that the methanolysis reaction rate increased from 1550 to 4800 mL.min⁻¹g⁻¹ and the ethylene glycolysis reaction rate increased from 923 to 3551 mL.min⁻¹g⁻¹. In the alcoholysis reaction catalyzed by PDMA cryogel beads, the activation energy was calculated as 19.34 and 22.77 kJ.mol⁻¹ for the methanolysis and ethylene glycolysis reactions, respectively. After six repetitions, the catalyst activity was calculated over 50% for NaBH₄ methanolysis and ethylene glycolysis.     

Performance of g-C3N4 nanoparticles by EDTA modification and protonation for hydrogen release from sodium borohydride methanolysis

Here, for the first time, a metal-free catalyst was synthesized by ethylenediamine tetra-acetic acid (EDTA) modification of the carbon nitride (g-C₃N₄) sample and protonation of the obtained sample. The catalyst was used for the production of H₂ from the methanolysis of sodium borohydride (NaBH₄). The EDTA modification and protonation of the g-C₃N₄ sample was confirmed by XRD, FTIR, SEM-EDX, and TEM analyses. During the hydrogen generation, NaBH₄ concentration effect, catalyst amount effect, temperature effect and catalyst reusability were investigated. The HGR value obtained with 2.5% NaBH₄ using 10 mg catalyst was 7571 mL min^?1g^?1. The activation energy (Ea) for the g–C₃N₄–EDTA-H catalyst was found to be 32.2 kJ mol^?1 The reusability of the g–C₃N₄–EDTA-H catalyst shows a catalytic performance of 72% even after its fifth use.     

Spirulina Platensis microalgae strain modified with phosphoric acid as a novel support material for Co–B catalysts: Its application to hydrogen production

Spirulina platensis is defined as the dried biomass of cyanobacteria in commercial use and is biomass with high carbon content. Spirulina platensis microalgae strain supported-CoB catalysts to produce hydrogen from sodium borohydride (NaBH₄) were prepared for the first time. The Spirulina platensis microalgae strain was modified with phosphoric acid (H₃PO₄) to proton. Then, the supported catalyst was performed to produce hydrogen from NaBH₄ hydrolysis. The optimum H₃PO₄ concentration, optimum Co amount, and optimum impregnation time of the H₃PO₄ with the microalgae strain were investigated. The maximum hydrogen production rate for the 30% CoB catalyst supported on microalgae strain treated with H₃PO₄ was found to be 3940 mL min⁻¹g⁻¹catalyst. X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), and scanning electron microscope (SEM) analysis were performed for characterization of CoB catalyst supported on Spirulina microalgae strain. After four consecutive uses, the performance and conversion values of this catalyst were investigated. At the same time, the effect of temperature on the hydrogen production from this hydrolysis reaction was examined. The activation energy with the CoB catalyst supported on Spirulina microalgae strain was calculated as 35.25 kJ mol⁻¹. According to the kinetic model of a power law, n value was found as 0.25 for kinetic studies.     

Apricot Kernel shell waste treated with phosphoric acid used as a green,metal-free catalyst for hydrogen generation from hydrolysis of sodium borohydride

In this study, grinded apricot kernel shell (GAKS) biobased waste was used for the first time as a cost-effective, efficient, green and metal-free catalyst for hydrogen generation from the hydrolysis reaction of sodium borohydride (NaBH₄). For the hydrogen production by NaBH₄ hydrolysis reaction, GAKS was treated with various acids (HCl, HNO₃, CH₃COOH, H₃PO₄), salt (ZnCl₂) and base (KOH). As a result, the phosphoric acid (H₃PO₄) demonstrated better catalytic activity than other chemical agents. The hydrolysis of NaBH₄ with the GAKS-catalyst (GAKS_cat) was studied depending on different parameters such as acid concentration, furnace burning temperature and time, catalyst amount, NaBH₄ concentration and hydrolysis reaction temperature. The obtained GAKS_cat was characterized by ICP-MS, elemental analysis, TGA, XRD, FT-IR, Boehm, TEM and SEM analyses and was evaluated for its catalytic activity in the hydrogen production from the hydrolysis reaction of NaBH₄. According to the results, the optimal H₃PO₄ percentage was found as 15%. The maximum hydrogen generation rate from the hydrolysis of NaBH₄ with the GAKS_cat was calculated as 20,199 mL min⁻¹ g_cat⁻¹. As a result, it can be said that GAKS treated with 15% H₃PO₄ as a catalyst for hydrogen production is an effective alternative due to its high hydrogen production rate.     

Poly(2-aminoethyl methacrylate) based microgels catalyst system to be used in hydrolysis and methanolysis of NaBH4 for H2 generation

The poly(2-aminoethyl methacrylate) (p(AEM)) microgels were synthesized by microemulsion polymerization technique and used for in situ metal nanoparticle preparation to render as p(AEM)-M (M: Co or Ni) microgel composites and were used in p(AEM) based poly ionic liquid (PIL) microgels. Next, these p(AEM)) based microgel materials were used as catalysts for hydrogen (H₂) production from both hydrolysis and methanolysis reactions of sodium borohydride (NaBH₄). It was found that the catalytic hydrolysis of the NaBH₄ reaction, catalyzed by p(AEM)-Co microgel composite was completed in 140 min, whereas the methanolysis of NaBH₄ methanolysis catalyzed by the PIL of p(AEM)⁺Cl⁻ microgels was completed in 5 min both with 250 ± 2 mL H₂ production. Furthermore, p(AEM)-Co microgel composite catalysts maintained 80% catalytic activity after 5 consecutive uses in NaBH₄ hydrolysis. On the other hand, p(AEM)⁺Cl⁻ microgels were found to afford more than 50% catalytic activity even after 20 repetitive use in NaBH₄ methanolysis due to superior regeneration ability. Moreover, activation energy values for p(AEM)-Co microgel composites catalyzed NaBH₄ hydrolysis reaction were calculated as 38.9 kJ/mol in comparison to 37.3 kJ/mol activation energy of p(AEM)⁺Cl⁻ microgel catalyzed methanolysis reaction.     

Chlorella vulgaris microalgae strain modified with zinc chloride as a new support material for hydrogen production from NaBH4 methanolysis using CuB,NiB, and FeB metal catalysts

This study aims to produce hydrogen (HG) from sodium borohydride (NaBH₄) methanolysis using CuB, NiB or FeB catalysts prepared with a different support material including C. vulgaris microalgae strain modified using zinc chloride (CMS-ZnCl₂). The NaBH₄ concentration, metal percentage in the supported-catalyst, the optimal ZnCl₂ percentage, and temperature effect on the NaBH₄ methanolysis were investigated. X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM) analysis were performed for the CMS-ZnCl₂-CuB characterization. Also, the low activation energy (Ea) of 22.71 kJ mol⁻¹ was found with the supported catalyst obtained. Under the same conditions, nearly 100% conversion was achieved in the reusability experiments repeated five times, but a gradual decrease in catalytic activity was observed after each use.     

Insight into the role of solvents in enhancing hydrogen production: Ru-Co nanoparticles catalyzed sodium borohydride dehydrogenation

Ru-Co nanoparticles prepared in nano-size by combustion derived of citric acid used sol-gel technique followed by calcination process at 450 °C. The external and internal properties of nano-sized catalyst were characterized by XRD, XPS, SEM, TEM, ICP-OES, and N₂ sorption techniques. The characterization results proved that nano-sized catalyst was mixture of cubic Co₃O₄ (18 nm) and tetragonal RuO₂ (40 nm) crystals with mesoporous structure (12.64 m²g^-1). Insight into the role of solvents for enhancing hydrogen production from Ru-Co nanoparticles catalyzed sodium borohydride (NaBH₄, SBH) was systematically studied by altering the dehydrogenation medium with water or methanol. The reaction kinetic performance of nano-sized catalyst was evaluated by performing both hydrogen generation reactions at various reaction temperatures, initial SBH concentration, and catalyst dosage to evaluate the hydrogen generation activity. Ru-Co nanoparticles exhibited exclusive catalytic performance for hydrogen generation by hydrolysis and methanolysis of SBH. The apparent activation energies (E_a) for the catalytic hydrolysis and methanolysis of SBH over Ru-Co nanoparticles were determined to be 20.02 kJ mol⁻¹ and 54.38 kJ mol⁻¹, respectively. Furthermore, Ru-Co nanoparticles also performed satisfied stability for both hydrolysis and methanolysis reactions. Beside both hydrogen generation was achived with fully conversion of SBH, Ru-Co nanoparticles promised good recyclability for at least 5 cycle for methanolysis of SBH.     

Synthesis of cobalt-doped catalyst for NaBH4 hydrolysis using eggshell biowaste

In the present study, a cobalt-doped catalyst was prepared from chicken eggshell powder (CEP) biowaste to be used in the hydrolysis of sodium borohydride (NaBH₄). In the presence of the prepared catalyst (CEP_cat), possible effects of the parameters of NaOH concentration (%), catalyst amount (g), NaBH₄ concentration (%), process temperature (^oC) and reusability affecting the hydrolysis of sodium borohydride were examined. The CEP_cat obtained was characterized with FT-IR, TGA, XRD, SEM and EDX analyses. The hydrogen generation rate (HGR) was determined as 432 mL g_Co⁻¹ min⁻¹ in the presence of 1 g CEP_cat, a CoO/CaO ratio of 10/90 and 1% NaBH₄ concentration. The activation energy of the NaBH₄ hydrolysis reaction was calculated as 16.78 kJ mol⁻¹. After 16 reuses of the CEP_cat there was no significant decrease in the hydrogen volume. Compared to the first use while there was an increase in the HGR. These results showed that the CEP_cat prepared has a significant advantage over other catalysts for use in NaBH₄ hydrolysis.     

Surface modification of graphitic carbon nitride nanoparticles with B,O and S doping/carbon vacancy for efficient dehydrogenation of sodium borohydride in methanol

Herein, the surface properties of graphitic carbon nitride (GCN) with sulphur(S), boron (B) and oxygen (O) dopants were improved. The heteroatom-doped metal-free GCN exhibited both rich surface functional groups and a carbon defect structure. These metal-free catalysts were used to obtain hydrogen (H₂) from the sodium borohydride (SB) methanolysis for the first time. Compared to GCN, S, B, and O doped GCN catalyst obtained showed a 2.2-fold improvement in H₂ production. HGR value obtained with B, O and S doped GCN (10 mg) via SB of 2.5% was 9166 ml min ⁻¹g⁻¹. XPS, SEM-EDX, TEM, FTIR, and XRD analyses were used for the structural properties of catalysts. The activation energy (Ea) for B, O and S doped GCN was 28.89 kJ mol⁻¹.     

A novel Microcystis aeruginosa supported manganese catalyst for hydrogen generation through methanolysis of sodium borohydride

In this study, Microcystis Aeruginosa (MA)- microalgae species was used for the first time as a support material with metal ions loading to fabricate a highly efficient catalyst for the hydrogen generation through methanolysis of sodium borohydride (NaBH₄). Microalgae was pre-treated with hydrochloric acid (3 M HCl) for 24 h at 80 °C. Subsequently, different metal ions (Mn, Co, and Mo) were loaded to the pre-treated samples. Finally, metal-loaded samples were subjected to burning in oven to fabricate the catalyst. Primarily, manganese metal was selected based on the best metal performance. Afterwards, different metal loading ratios, burning temperatures and burning times were evaluated to synthesize the optimal MA-HCl-Mn catalyst. Results showed the optimal conditions as Mn ratio, burning temperature and time as 50%, 500 °C and 45 min, respectively. To characterize the catalyst, FTIR, SEM-EDX, XRD, XPS and TEM analyses were performed. Hydrogen generation via methanolysis was performed at various NaBH4 ratio of 1–7.5% while changing concentrations from 0.05 to 0.25 g catalysts with diverge temperatures of (30, 40, 50 and 60 °C). The maximum hydrogen generation rate (HGR) by this novel catalyst was found as 4335.3, 5949.9, 7649.4 and 8758.9 mLmin⁻¹gcat⁻¹, respectively. Furthermore, the activation energy was determined to be 8.46 kJ mol⁻¹.