Influence of the using of methanol instead of water in the preparation of Co–B–TiO2 catalyst for hydrogen production by NaBH4 hydrolysis and plasma treatment effect on the Co–B–TiO2 catalyst

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 1 ( 2 0 1 6 ) 2 5 3 9 e2 5 4 6

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Influence of the using of methanol instead of water in the preparation of CoeBeTiO2 catalyst for hydrogen production by NaBH4 hydrolysis and plasma treatment effect on the CoeBeTiO2 catalyst b € _ Omer S‚ahin a, M.Sait Izgi , Erhan Onat b, Cafer Saka c,* a

Faculty of Engineering and Architecture, Siirt University, 56100 Siirt, Turkey Faculty of Science and Letters, Bitlis Eren University, Bitlis, Turkey c School of Healty, Siirt University, 56100 Siirt, Turkey b

article info

abstract

Article history:

In this work, methanol was used as an alternative to water. Our objective is to study the

Received 1 October 2015

influence of the using of methanol instead of water in the preparation of CoeBeTiO2

Received in revised form

catalyst. It is also expected to improve the activity of CoeBeTiO2 catalyst by plasma

18 November 2015

treatment for the hydrogen generation from hydrolysis of NaBH4. The prepared catalysts

Accepted 19 November 2015

were characterized using BET (N2 adsorption), SEM (scanning electron microscopy), XRD (X-

Available online 23 December 2015

ray diffraction) and FTIR (Fourier transform infrared) methods. The CoeBeTiO2 catalyst prepared in methanol shows maximum hydrogen generation rate, which is about 3.0 times

Keywords:

higher than that obtained for CoeBeTiO2 catalyst prepared in water. The maximum

Cold plasma

hydrogen generation rates for the CoeBeTiO2 catalysts prepared in water and methanol

Sodium borohydride

were 1017 and 3031 mL/min/g, respectively. In addition, the maximum hydrogen genera-

Methanol

tion rates for the plasma treated CoeBeTiO2 catalysts prepared in water and methanol

CoeBeTiO2 catalysts

were 1320 and 2656 mL/min/g, respectively. The activation energies of nth-order reaction

Hydrogen generation

model for the hydrogen production from hydrolysis of NaBH4 with the plasma treated Co eB/TiO2 catalyst prepared in methanol and CoeB/TiO2 catalyst prepared in methanol can be obtained from the slope and intercept of the regression line, being 41.29 and 36.24 kJ/ mol, respectively. Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Introduction Hydrogen is considered as one of the possible alternatives to fulfil the increasing energy demands of the world with depletion of conventional fossil fuel reserves. Hydrogen is the

future energy carrier that can efficiently be used more widely in the near future because it is environmentally friendly. The hydrolysis of chemical hydride for hydrogen generation has received much attention because of their efficient hydrogen releasing capacities [1].

* Corresponding author. Tel.: þ90 (484) 223 12 24; fax: þ90 (484) 223 66 31. E-mail address: [email protected] (C. Saka). http://dx.doi.org/10.1016/j.ijhydene.2015.11.094 0360-3199/Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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Among the metal borohydride, sodium borohydride (NaBH4) has been receiving significant interest. NaBH4 is a stable, non-flammable, easy-to-handle and non-toxic chemical hydride that is capable of storing 10.8 wt.% of hydrogen [2]. Hydrolysis of NaBH4 requires a suitable catalyst in alkaline condition for generation of hydrogen due to its stability, high rate production and reusability of by-product [3]. Moreover, the reaction is given as follows equation (1)

NaBH4 þ 2H2O / 4H2 þ NaBO2 þ heat

(1)

The NaBH4 hydrolysis reaction is very fast in the presence of a catalyst, and there is no need to supply external heat for the reaction to occur. Different catalysts such as noble metals Ru [4,5], Rh [6], Pt [7], and Pd [8], transition metals such as Ni [9,10], Co and Co based [1,11e14] and metal borides, such as CoeB [15e17], NieB [18], CoeBeP [19], CoeNiePeB [20] and CoeWeB [21] have been extensively studied. Cobalt boride is a good candidate for hydrogen generation due to their high activity and low cost. However, the major drawback of cobalt catalysts is rapid deactivation over cycles because of surface poisoning [22]. These catalysts are commonly synthesized by chemical-reduction method. A simplest and most common method is the reduction of metal ions with NaBH4. However, the exothermic nature of the reduction reaction involves high surface energy causing metaleboride particles to agglomerate. This particle agglomeration lowers the effective surface area of the catalyst powder thus limiting its catalytic activity [23,24]. It is possible to improve the heterogeneous catalyst activity over modifying the support by approaches. The catalyst support materials can prevent agglomeration of active particles with a high metal dispersion. Therefore, the heterogeneous catalyst with broad supports such as Al2O3, TiO2, ZrO2, ZnO and others is applied based on its broad availability and costeffective modes of synthesis. Schlesinger et al. [25] made a detailed study of the hydrolysis reaction of NaBH4 for hydrogen generation. As an alternative to the use of water, methanol has been proposed as efficient solvolytic agents. The methanolysis by-product of NaBH4 has been previously reported to be the methoxyborate NaB(OCH3)4 as indicated in equation (1) [26e30]. The overall reaction can be described as follows:

high chemical reactivity with low operational cost that will result in less energy consumption and minimum electrode erosion and appear as an interesting alternative to the conventional methods [33,34]. In this work, methanol was used as reactant as an alternative to water. The aim of this study is to develop a feasible new catalyst system prepared in methanol for hydrogen generation by catalytic hydrolysis of NaBH4. In addition, plasma treated CoeBeTiO2 catalysts prepared in methanol and water was applied to the system for the hydrogen generation from hydrolysis of NaBH4. Our objective is to study the influence of the using of methanol instead of water in the preparation of CoeBeTiO2 catalyst. It is also expected to improve the activity of CoeBeTiO2 catalyst by plasma treatment for the hydrogen generation from hydrolysis of NaBH4.. The effects on the CoeBeTiO2 catalyst of NaBH4 concentration and temperature on the rate of hydrolysis were investigated. Catalytic materials were characterized by BET, SEM, XRD and FTIR methods.

Experimental Preparation of catalysts in methanol and water Preparation of catalyst in methanol Appropriate amount of CoCl2.6H2O, TiO2 and citric acid were dissolved in 50 mL methanol in a flask, followed by adding reducing solution NaBH4 dropwise with vigorous stirring. Citric acid was used as the complexing agent to control the rate of release of free metal ions for the reduction reaction [35]. During reduction, the flask was kept in an ice-water bath in order to prevent severe reaction. Then, the black precipitate was produced. The resulted precipitate was filtered and washed with ethanol until pH reached 7, then dried in N2 at 80  C overnight.

Preparation of catalyst in water Appropriate amount of CoCl2.6H2O, TiO2 and citric acid were dissolved in 50 mL water in a flask, followed by adding reducing solution NaBH4 drop wise with vigorous stirring. During reduction, the flask was kept in an ice-water bath in order to prevent severe reaction. Then, the black precipitate was produced. The resulted precipitate was filtered and washed with ethanol until pH reached 7, then dried in N2 at 80  C overnight.

Plasma treatment NaBH4 þ 4CH3OH / NaB(OCH3)4 þ 4H2 þ heat

(2)

Compared to a hydrolysis system, the methanolysis system possesses some favourable advantages because it is high potential gravimetric hydrogen density, the possibility of subzero hydrogen generation, and the fact that the reaction product (NaB (OCH3)4) does not have tendency to plug the reactors as occurs with NaBO2. Most of all, the hydrolysis of NaB (OCH3)4 by-products liberate the consumed methanol efficiently, which thus can be continuously recycled and reused in methanolysis reaction [26,31,32]. Cold plasma treatment is a green technique and recently has attracted significant attention for preparing high performance supported metal catalysts. Plasma processes combine

The plasma treatment of CoeBeTiO2 catalysts prepared in methanol and water was performed with a plasma system at low Ar pressure. Before plasma treatment, the chamber was pumped down to less than 104 Pa. To create the plasma, N2 gas was injected into the chamber depending on plasma applying time 20 min. Finally, the plasma treated catalyst samples were tested for the hydrogen generation from NaBH4 hydrolysis. All reagents used in this research were of analytical grade and used as received.

Catalyst characterization The surface morphology of all catalysts was studied by scanning electron microscope (Zeiss EVO 50 Model).

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Structural characterization of the catalysts was performed by conventional XRD in the 2q angle between 10 and 70 , at a step width of 0.02 and by counting 10 s at each step with a PW 1710 diffract meter with Cu-Ka radiation (l ¼ 1.5418 Å). FTIR were obtained at room temperature on a Nicolet 520 Fourier transform instrument at 2 cm1 of resolution by collecting 100 scans. The spectra were measured in the wave number range of 400e4000 cm1. The pore structures of the samples were performed on a surface area analyzer (Quantachrome Corporation, USA) through N2 adsorption/desorption at  196  C. Samples were degassed under vacuum at 200  C for 3 h. The specific surface areas of the samples were calculated from the N2 adsorption/ desorption isotherms using the BrunauereEmmetteTeller (BET) equation in the relative pressure range p/p0 ¼ 0.003e0.2. Pore volumes were calculated using the t-plot method.

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Co-B-TiO2(Methanol) Co-B-TiO2(Water)

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Co-B-TiO2(Water+Plasma) 100 Co-B-TiO2(Methanol+Plasma) 0

Hydrogen generation measurement The detailed procedure is as following: 10 mL solution containing 2.5 wt% NaBH4 and 10 wt% NaOH was placed in a 3neck round bottom flash with a temperature-control device. The catalysts (25 mg) catalysts were dipped into the reaction flask with stirring. The volume of hydrogen generation was measured by water replacement method. An outlet tube was connected to the flask for collecting evolved hydrogen gas. The other end of the tube was placed under an inverted waterfilled gas burette, which was situated in a water-filled container. The generated hydrogen quantity was measured through a gas volumetric method. A measured volume of released gas was subsequently converted into yield of produced hydrogen after the total amount of gas had been collected.

Results and discussion Effects of water, methanol and plasma treatment To compare the activity of the catalysts, experiments have been performed. The activities CoeBeTiO2 catalysts prepared in water and methanol with 2.5 wt% NaBH4 hydrolysis were evaluated in 10 wt% NaOH at 30  C. The volume change of hydrogen as a function of time is shown in Fig. 1. Hydrogen production rate was greatly enhanced with the presence of the catalyst prepared in methanol and plasma treated catalyst. Compared with the catalyst prepared in water, the CoeBeTiO2 catalyst prepared in methanol has a higher hydrogen production rate. It can be seen that the hydrogen production rate of hydrolysis reaction of NaBH4 with the CoeBeTiO2 catalyst prepared in water is completed in 32 min; while hydrogen production rate of hydrolysis reaction of NaBH4 with the CoeBeTiO2 catalyst prepared in methanol is completed in 18 min. The maximum hydrogen generation rates for the CoeBeTiO2 catalysts prepared in water and methanol were 1017 and 3031 mL/min/g, respectively. The CoeBeTiO2 catalyst prepared in methanol shows maximum hydrogen generation rate, which is about 3.0 times higher than that obtained for CoeBeTiO2 catalyst prepared in water. It is shown that CoeBeTiO2 catalyst prepared in methanol has

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Fig. 1 e Effects of water, methanol and plasma treatment on the CoeBeTiO2 catalysts with 2.5 wt% NaBH4 hydrolysis in 10 wt% NaOH at 30  C. effective catalytic property for hydrolysis of NaBH4. Therefore, it can be concluded that the improvement of performance of the CoeBeTiO2 catalyst by using methanol is caused from the promotion of hydrolysis reaction by an increase of reactive sites. Fernandes et al. stated that methanol displays hydrophilic characteristics associated to its solubility in water, but is also known by its hydrophobic character. Breakdown of hydrogen-bonded chains, characteristics of pure methanol, is expected in water mixtures with high methanol concentrations. This could bear implications in the high-observed reaction rates [27]. OeH bond of water is more polarized than that of methanol, which results in a stronger adsorption of water onto the catalyst surface. Therefore, methanol may be repelled from the catalyst surface due to its hydrophobic character induced by CH3 radicals, which exerts a negative effect on the methanolysis reaction kinetics [32]. In addition, the maximum hydrogen generation rates for the plasma treated CoeBeTiO2 catalysts prepared in water and methanol were 1017 and 2656 mL/min/g, respectively. Plasma is composed of highly excited atomic, molecular, ionic, and radical species. It can be seen that introducing catalysts into the plasma treatment can induce a shift in the distribution of the accelerated electrons. New reactive species can also be generated during the treatment. Introducing heterogeneous catalysts in the plasma discharge may increase the production of active species. Thus, with plasma techniques it is possible to obtain catalytically active materials with new surface properties that will result in novel activity and selectivity for these reactions compared with conventional processes [36].

Catalyst characterization XRD analysis The X-ray diffraction patterns for the hydrogen production from NaBH4 with CoeBeTiO2 catalysts prepared in water (a),

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plasma treated CoeBeTiO2 catalyst prepared in water(b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol(d) are presented in Fig. 2. In Fig. 2, XRD patterns exhibited strong diffraction peaks at 27 , 36 , 42 and 55 indicating TiO2 in the rutile phase. All peaks are in good agreement with the standard spectrum (JCPDS no.: 88e1175 and 84e1286). However, no characteristic peaks of Co and/or B are observed in the XRD pattern of CoeBeTiO2, indicating that the particles are well dispersed on the surface of TiO2 particles. The XRD patterns for all catalyst samples exhibited similar patterns as seen in Fig. 2. After plasma treatment, all samples exhibited XRD peaks, which were identical with those for the corresponding titania supports. Apparently, the peaks at 42 and 55 of the rutile phase gradually increased peak intensity with the plasma treatment. However, the peak at 42 for plasma treated CoeBeTiO2 catalyst prepared in methanol was less apparent. It can be seen that there is no obvious peak appears for unsupported CoB catalyst, indicating its non-crystalline structure. This result is corresponding to the general structure of CoB catalyst [37].

SEM analysis Fig. 3a, b, c, d present the SEM images for the hydrogen production from NaBH4 with CoeBeTiO2 catalysts prepared in water (a), plasma treated CoeBeTiO2 catalyst prepared in water (b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol(d). In the case of the plasma treated CoeBeTiO2 catalyst prepared in water (b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalysts for the hydrogen production with NaBH4, more uniform and regular surface was occurred compared to the CoeBeTiO2 catalyst prepared in water for the hydrogen production with NaBH4. There are many uniform CoeB particles covering the surface of TiO2 support. The external surface of catalyst granule is shown in all figures and the light or white patches on the catalyst granule surface represent cobalt oxides species on the surface. Those images show global and uniform particles, which are coherent together. These results confirmed the existence of CoeB atoms in the solid catalysts but the XRD patterns do not show any peaks related to CoeB. Therefore, it may be concluded that CoeB ions are uniformly dispersed among the rutile crystallites.

BET surface area analysis Specific surface area, total pore volume, and average diameter of modified TiO2 are summarized in Table 1. It can be observed that the surface area of the CoeBeTiO2 catalyst increases by using the plasma treatment on the CoeBeTiO2 catalysts and preparation in methanol. It must be noticed the higher surface area of the plasma treated CoeBeTiO2 catalyst prepared in methanol. The pore volume of the plasma treated CoeBeTiO2 catalyst prepared in methanol is considerably higher than that of other catalysts. The BET surface area of commercial TiO2 anatase (Hombikat) sample obtained by N2 physisorption at liquid nitrogen temperature was found to be 179 m2/g. Since the surface areas of the catalysts were different, one might think that a change in surface areas of the supports probably has the effect on rates as well. The plasma treated CoeBeTiO2 catalyst prepared in methanol shows superior catalytic performance to the plasma treated CoeBeTiO2 catalyst prepared in water, maybe because of its higher surface area so that NaBH4 can reach the active sites easily and the products can leave the active sites smoothly.

FTIR analysis

Fig. 2 e X-ray diffraction patterns for the hydrogen production from 2.5 wt% NaBH4 hydrolysis in 10 wt% NaOH at 30  C with CoeBeTiO2 catalysts prepared in water (a), plasma treated CoeBeTiO2 catalyst prepared in water(b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol with plasma applying time 20 min (d).

The FTIR spectra of the hydrogen production from NaBH4 with the CoeBeTiO2 catalysts prepared in water (a), plasma treated CoeBeTiO2 catalyst prepared in water (b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol (d), are illustrated in Fig. 4. The FTIR spectrum of the CoeBeTiO2 catalysts was nearly the same. The IR spectrum of OH groups in the CoeBeTiO2 catalysts shows peaks at 3450 and 1650 cm1 for all samples. The peaks around 807e850 cm1 may be assigned to stretching vibration of OeO. The peak observed at 660 cm1 may be assigned to the vibration of the TieOeO bond [38]. In principle, a peak around 1450 cm1 reveals BeO stretching. The peak at 1100 cm1 for BeH stretching bond was clearly visible in each of the other spectra.

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Fig. 3 e SEM images for the hydrogen production from 2.5 wt% NaBH4 hydrolysis in 10 wt% NaOH at 30  C with CoeBeTiO2 catalysts prepared in water (a), plasma treated CoeBeTiO2 catalyst prepared in water (b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol with plasma applying time 20 min (d).

Table 1 e BET surface area and pore volume measurements of the prepared catalysts. Catalyst

SBET (m2/g)

CoeB/TiO2(water) 24.158 34.040 CoeB/TiO2 (plasma and water) CoeB/TiO2 (methanol) 18.561 179.93 CoeB/TiO2 (plasma and methanol)

Average pore ratio (nm)

Pore volume (cm3/g)

14.769 10.700

0.1784 0.1821

18.970 11.906

0.1761 0.1071

Effect of NaBH4 concentration Fig. 5 illustrates the hydrogen generation rates with different NaBH4 concentration, i.e. 2.5, 5 and 7.5 wt%, in 5 wt% NaOH solution with the plasma treated CoeBeTiO2 catalyst prepared in methanol for the hydrogen production with hydrolysis of NaBH4, where the hydrogen generation rate decreases with the increase in NaBH4 concentration. However, when the concentration of NaBH4 ranges from 2.5 to 7.5 wt%, the hydrogen volume was increased from 678 to 1905 mL. It should be noticed that NaBO2 was produced simultaneously with hydrogen, and higher initial NaBH4 concentration can lead to more NaBO2 accumulated on the catalyst surface and

Fig. 4 e FTIR spectra of the hydrogen production from 2.5 wt% NaBH4 hydrolysis in 10 wt% NaOH at 30  C with the CoeBeTiO2 catalysts prepared in water (a), plasma treated CoeBeTiO2 catalyst prepared in water (b), CoeBeTiO2 catalyst prepared in methanol (c), and plasma treated CoeBeTiO2 catalyst prepared in methanol with plasma applying time 20 min (d).

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Fig. 5 e Effect of NaBH4 concentration on the hydrogen generation rate measured using x wt% NaBH4(x ¼ 2.5, 5, 7.5) þ 10 wt% NaOH solutions 30  C, using 25 mg catalyst.

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Fig. 8 e Arrhenius equation according to nth-order reaction mod for the CoeBeTiO2 catalyst prepared in methanol.

Effect of temperature The generation of hydrogen from hydrolysis of NaBH4 with the plasma treated CoeBeTiO2 catalyst prepared in methanol and CoeBeTiO2 catalyst prepared in methanol at varying temperatures from 30  C to 60  C is shown in Fig. 6. As expected the higher the hydrolysis temperature, the higher the hydrogen yield percentage and the shorter the hydrolysis time. This is a common phenomenon because the elevated temperature can obviously accelerate the reaction rate between NaBH4 and H2O.

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Fig. 6 e Effect of temperature on the hydrogen generation rate measured using 2.5% NaBH4 þ 10 wt% NaOH solutions using 25 mg catalyst.

in the solution because of the low solubility of NaBO2 under alkaline condition. Consequently, the catalytic active sites on the catalyst would be blocked, the solution viscosity would increase and the mass transfer would be impeded [39].

Fig. 7 e Arrhenius equation according to nth-order reaction mod for the plasma treated CoeBeTiO2 catalyst prepared in methanol.

Table 2 e Comparison of catalytic performance of various catalyst for hydrolysis and methanolysis of NaBH4. Catalyst

CoeB prepared using methanol (hydrolysis) CoeB prepared using water(hydrolysis) CoeB prepared using water(hydrolysis) CoeNieB(hydrolysis) CoeFeeB(hydrolysis) CoeCueB(hydrolysis) CoeCreB(hydrolysis) CoeMoeB(hydrolysis) CoeWeB(hydrolysis) CoeCueB prepared using methanol (hydrolysis) þ plasma treatment CoeCueB prepared using methanol (hydrolysis) CoeCueB prepared using water (hydrolysis) CoeB/TiO2(hydrolysis) CoeB/Al2O3(hydrolysis) CoeB/CeO2(hydrolysis) CoeBeTiO2 prepared in water ((hydrolysis) plasma treated CoeBeTiO2 prepared in methanol ((hydrolysis) CoeBeTiO2 prepared in methanol ((hydrolysis)

References Hydrogen production rate (mL/min/g) 1950

[40]

1680

[40]

1127

[41]

1175 1300 2210 3400 2875 2570 4972

[42] [42] [42] [42] [42] [42] [43]

3998

[43]

734.4

[43]

12,500 11,650 10,390 1017

[44] [44] [44] This study

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For a batch reactor, the nth-order kinetics can be described as: rNaBH4 ¼

dCNaBH4 n ¼ kCNaBH4 dt

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from the slope and intercept of the regression line, being 41.29 and 36.24 kJ/mol, respectively.

(3)

By separating and integrating Eq. (3), the following is obtained:

Acknowledgment

 1  1n CNaBH4 ðt¼0Þ  C1n NaBH4 ðt¼tÞ ¼ kn t ðns1Þ n1

The authors are grateful to the Research Foundation of Bitlis Eren University for financial support under Project BEBAP 2015.08.

(4)

1n 1 ðC1n Therefore, a plot of n1 NaBH4 ðt¼0Þ  CNaBH4 ðt¼tÞ Þ versus time should give a straight line through the origin, and the slope of the line can be used to calculate nth-order rate constant, kn. The values of n, representing the hydrolysis reaction rate order of NaBH4 with the plasma treated CoeBeTiO2 catalyst prepared in methanol and CoeBeTiO2 catalyst prepared in methanol, are found to be about 0.66. In order to find Arrhenius constants (activation energy, E, for nth-order reaction model, the plot of ln(k) versus 1/T for the temperatures of 30, 40, 50 and 60  C was obtained for the plasma treated CoeBeTiO2 catalyst prepared in methanol and CoeBeTiO2 catalyst prepared in methanol, respectively (Figs. 7 and 8). The activation energies of nth-order reaction model for the hydrogen production from hydrolysis of NaBH4 with the plasma treated CoeBeTiO2 catalyst prepared in methanol and CoeBeTiO2 catalyst prepared in methanol can be obtained from the slope and intercept of the regression line, being 41.29 and 36.24 kJ mol1, respectively. Arrhenius equation (5) is given as follows;

lnk ¼ lnA  Ea=RT

(5)

where R is the universal gas constant (8.314 kJ/K/mol), k is the rate constant (mL/min/g), A is the pre-exponential factor and T is absolute temperature (K). Comparison of catalytic performance of various catalyst for hydrolysis and methanolysis of NaBH4 is given Table 2 [40e44].

Conclusions In this study, CoeBeTiO2 catalysts prepared in methanol and water for the hydrogen production by hydrolysis of NaBH4 have been prepared. In addition, plasma treatment on the CoeBeTiO2 catalysts prepared in methanol and water for the hydrogen production by hydrolysis of NaBH4 has been applied. The hydrogen production rate of hydrolysis reaction of NaBH4 with the CoeBeTiO2 catalyst prepared in water is completed in 32 min; while hydrogen production rate of hydrolysis reaction of NaBH4 with the CoeBeTiO2 catalyst prepared in methanol is completed in 18 min. The maximum hydrogen generation rates for the CoeBeTiO2 catalysts prepared in water and methanol were 1017 and 3031 mL/min/g, respectively. In addition, the maximum hydrogen generation rates for the plasma treated CoeBeTiO2 catalysts prepared in water and methanol were 1320 and 2656 mL/min/g, respectively. The activation energies of nth-order reaction model for the hydrogen production from hydrolysis of NaBH4 with the plasma treated CoeBeTiO2 catalyst prepared in methanol and CoeBeTiO2 catalyst prepared in methanol can be obtained

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