班級：化材四乙 老師：謝慶東 成員：蔡妃虹 49640060 楊雅琇 49640097

Introduction

在水解反應加入了觸媒會提高產氫的效率，而有機和無機酸能提高效率，但通常反應無法控制。在一個可控制的反應加入固態的催化劑 (例如貴金屬、過度金屬 )可以加速水解反應。

過度金屬、金屬鹽類一般用來加速硼氫化鈉水解反應，由於良好得催化性能和低成本以鈷、鎳、硼金屬最常被使用。

Co(Co-B,Co-P)、 Ni(Ni-B,Ni-P)催化占有較高的優勢。

Experimental製備 Co-P-B

CoCl2+NaH2Po2

+NaBH4323K， N2

用 H2O+C2H5OH清洗過濾

製備 Co-B

與製備 Co-P-B方法相似，差別在於沒有添加 NaH2Po2

製備 Co-P

CoCl2+NaH2Po2

+NaOH323K

用 H2O+C2H5OH清洗過濾

Fig 1. Hydrogen generation yield as a function of reaction time obtained by hydrolysis of alkaline NaBH4(0.025M)solution with Co-B,Co-P,andCo-P-B(B/P molar ratio = 2.5)catalyst powders.Inset shows the extened plot of hydrogen generation yield as function of time for Co-P catalyst.

Results and discussion

Fig. 2. SEM micrographs of (a) Co–B, (b) Co–P, and (c) Co–P–B (B/P molar ratio = 2.5) catalyst powders.

Fig. 3. X-ray photoelectron spectra of Co2p3/2, P2p, and B1s level for Co–B, Co–P, and Co–P–B (B/P molar ratio = 2.5) catalyst powders.

Fig. 4. Hydrogen generation yield as a function of reaction time obtained by hydrolysis of alkaline NaBH4 (0.025M) solution with Co–B and Co–P–B catalysts with different B/P molar ratio ranging from 1 to 5. Inset shows the maximum H2 generation rate (Rmax) obtained with Co–P–B catalyst as a function of B/P molar ratio. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 5. Hydrogen generation yield as a function of reaction time obtained by hydrolysis of alkaline NaBH4 (0.025M) solution with Co–P–B (B/P = 2.5) catalyst powders untreated and heat-treated in Ar atmosphere at 673 and 773K for 2 h. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 6. XRD pattern of Co–P–B (B/P molar ratio = 2.5) catalyst powder untreated andheat-treated in Ar atmosphere at 673 and 773K for 2 h.

Fig. 7. SEM micrographs of: (a) untreated Co–P–B (B/P molar ratio = 2.5) catalyst powder and heat-treated (b) at 673K, (c) and (d) at 773K in Ar atmosphere for 2 h.

Fig. 8. Hydrogen generation yield as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst measured at 4 different solution temperatures by hydrolysis of alkaline NaBH4 (0.025M) solution. Inset shows the Arrhenius plot of the H2 generation rates with Co–P–B (B/P molar ratio = 2.5) powder. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 9. Hydrogen generation yield as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst of 5 different concentrations obtained by hydrolysis of alkaline NaBH4 (0.025M) solution. Insert shows the plot of ln(H2 generation rate) vs ln(concentration of catalyst). (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 10. Hydrogen generated volume as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst obtained by hydrolysis of alkaline NaBH4 (0.25M) solution containing 5 different concentrations of NaOH ranging from 0.25 to 2.5 M. Insert shows the plot of ln(H2 generation rate) vs ln(concentration of NaOH) to determine the reaction order with respect to NaOH. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 11. (a) Hydrogen generated volume as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst obtained by hydrolysis of alkaline NaBH4 solution containing different concentrations of NaBH4 ranging from 0.005 to 0.05 M. (b) Plot of ln(H2 generation rate) vs ln(concentration of NaBH4) to determine the reaction order with respect to NaBH4. (For interpretation of the references to color in thisartwork, the reader is referred to the web version of the article.)

Fig. 12. Hydrogen generated volume as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst obtained by hydrolysis of alkaline NaBH4 solution containing different concentrations of NaBH4 ranging from 0.075 to 0.25 M. Inset shows the plot of ln(H2 generation rate) vs ln(concentration of NaBH4) to determine the reaction order with respect to NaBH4. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 13. Hydrogen generated volume as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst obtained by hydrolysis of alkalineNaBH4 solution containing low(0.025M) and high (0.25M) concentrations ofNaBH4. Symbols represent the experimental value and the solid line is obtained by fitting. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 14. Hydrogen generation yield as a function of reaction time obtained by hydrolysis of alkalineNaBH4 (0.025M) solution with Co–P–B (B/P molar ratio = 2.5) catalyst exposed to ambient atmosphere for several intervals of time. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 15. Cyclic behavior of Co–P–B (B/P molar ratio = 2.5) catalyst powder on hydrogen generation yield as a function of reaction time measured using hydrolysis of 0.025M NaBH4 alkaline solution. (For interpretation of the references to color in this artwork, the reader is referred to the web version of the article.)

Fig. 16. Hydrogen generated volume and rate as a function of reaction time with Co–P–B (B/P molar ratio = 2.5) catalyst obtained by hydrolysis of alkaline NaBH4 solution containing 1 wt% of NaBH4 and 5 wt% of NaOH.

Table 2Comparison of maximum H2 generation rate between our present Co–P–B catalystpowder and various catalysts reported in the literature.

Conclusions

1. 催化 NaBH4的 Catalyst以 Co-P-B最好。2. Co-P-B( B/P =2.5)這樣的比例最理想。3. 一級動力學的擴散與 BH4有關，穩定性高可用於商業用途。