Effect of promoter on nickel catalyst of hydrogen production from ammonia decomposition：An optimization study

Autor: Pei-Yun Chen, 陳沛云
Rok vydání: 2013
Druh dokumentu: 學位論文 ; thesis
Popis: 101
The effect of the molar ratio of promoter-barium (Ba)/catalyst-nickel (Ni), the flow rate of NH3 and the temperature of reaction on the decomposition efficiency of ammonia in terms of the production efficiency of hydrogen was investigated in this study. The results showed that the decomposition efficiency of NH3 and hydrogen formation would increase with increasing the molar ratio of Ba/Ni. The decomposition of NH3 would reach the highest efficiency, at the condition of a Ni/(SiO2•Al2O3) molar ratio of 0.10. Ba is not added nickel catalyst promoter, gas hourly space velocity (GHSV) of 12,000 mL / gcat h, the reaction temperature is 723 K, the decomposition efficiency of NH3 was about 40 percent, when adding Ba / Ni molar ratio to 0.10, which decomposition efficiency of NH3 of was nearly 70 percent, indicating the effective promoting effect of Ba/Ni catalyst on the decomposition of NH3. At last, a Box-Behnken design of surface response methodology (RSM) was adopted to investigate the effect of three major process factors including the reaction temperature, molar ratio of promoter and catalyst and, NH3 inflow rate, on the decomposition efficiency of ammonia reaction. With the assistance of ANOVA analysis, it was found that the factor of reaction temperature has the most significant effect on the decomposition efficiency while molar ratio of promoter and catalyst showed the least effect. Optimal reaction conditions based on RSM were established as under reaction temperature, molar ratio of promoter and catalyst, and NH3 inflow rate were T= 738 K; Ba/Ni= 0.10; NH3= 3 mL/min、T= 758 K; Ba/Ni= 0.10; NH3= 6 mL/min and T= 783 K; Ba/Ni= 0.10; NH3= 9 mL/min, respectively, which could reach the target value of decomposition efficiency 80%。 On the basis of the results obtained in this study, it was revealed that the decomposition efficiency of ammonia in terms of the production efficiency of hydrogen would be promoted by adding an appropriate molar ratio of Ni/(SiO2•Al2O3) in reactor, even at a lower reaction temperature and a higher flow rate of NH3.
Databáze: Networked Digital Library of Theses & Dissertations
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