| Efficient dehydrogenation of cyclohexane catalyzed by Pt-Sn/Al2O3 under multiphase reaction conditions was investigated in this work.The uniform design(UD)method was employed to evaluate the influences of heating temperature,feeding rate of cyclohexane and catalyst dosage on the total amount of hydrogen produced in 2 h,the dehydrogenation conversion of cyclohexane and the relative activity of the catalyst.By the experimental results,analysis the regressed second-order polynomial models and the optimum reaction conditions for each response was obtained.Based on the analysis of the logistics and energy balance of the reaction system,the models of the dehydrogenation conversion of cyclohexane and the hydrogen production rate under "wet-dry" multiphase reaction condition were established.Moreover,a novel concept of the on-board LOH hydrogen storage system was designed based on LOH multiphase dehydrogenation technology.Firstly,the continuous dehydrogenation of cyclohexane catalyzed by Pt-Sn/Al2O3 was studied in this work.The experiment was conducted using the uniform design table U10(102x5)under the following experimental conditions:the heating temperature ranged from 292 ? to 382 ?,the feeding rate of cyclohexane ranged from 0.318 to 1.2 mLˇmin-1,and the catalyst dosage ranged from 6 to 14 g.The changes of the total amount of hydrogen produced in 2 h,the dehydrogenation conversion,the relative activity of the catalyst and the hydrogen purity were investigated.The experimental results proved that the Pt-Sn/Al2O3 exhibited a very good performance in the dehydrogenation of cyclohexane under multiphase reaction conditions.Secondly,the regressed second-order polynomial models of the total amount of hydrogen produced in 2 h,the dehydrogenation conversion of cyclohexane and the relative activity of the catalyst were obtained by using Data Processing System(DPS Version 7.05),and also the optimal reaction conditions for each response were obtained.The final optimal results were showed as the following:under the optimal conditions of the heating temperature at 382 ?,feeding rate of 1.067 mLˇmin-1,and catalyst dosage of 14 g,the maximal total amount of hydrogen produced in 2 h was 32.404 L;under the optimal conditions of the heating temperature at 382 ?,feeding rate of 0.283 mLˇmin-1,and catalyst dosage of 10 g,the dehydrogenation conversion of cyclohexane was 69.62%;under the optimal conditions of the heating temperature at 382 ?,feeding rate of 0.982 mLˇmin-1,and catalyst dosage of 12 g,the relative activity of the catalyst remained at 0.9835.In the third section of the thesis,based on the analysis of the logistics and energy balance of the reaction system,the models of dehydrogenation conversion and hydrogen production rate of the dehydrogenation reaction system of cyclohexane catalyzed by Pt-Sn/Al2O3 under "wet-dry" multiphase reaction conditions were established.In a jet cycle,the theoretical values calculated by the models as following:the dehydrogenation conversion of cyclohexane could reach 63.93%,and the average hydrogen production rate 4.926 mmolˇmin-1.The model predictions fit very well with the experimental results.Moreover,the conceptual design of an on-board LOH hydrogen storage system for hydrogen fuel vehicles was proposed on the basis of theoretical and experimental studies,and the operating modes of city driving,long distance travel as well as high power operation three were designed.According to the optimization experimental results:in theory,120 L cyclohexane fuel could produce about 4.66 kg high purity hydrogen at the conversion of 70%,which can travel about 606 Km;and if the fuel was recycle used,it will produce about 6.68 kg H2 at utilization rate of 100%,which can travel about 868 Km.The design had great reference value in the future new energy vehicles field,and it will open up a new route for the development of hydrogen cars. |
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