| Vapor phase catalytic exchange (VPCE) is one of the most promising solutions for water detritiation and heavy water production. In recent years, the inland nuclear power plants have developed rapidly, and will be on the agendas of construction. Thus, VPCE is considered to play an important role in water detritiation due to its high efficiency and low cost. This thesis aimed at developing a new type of hydrophilic catalyst during new VPCE (N-VPCE) process. To satisfy the industrial application, it is necessary to study such catalyst which has a low cost and perform a high catalytic activity. In this work for catalyst, I studied on activated Ni loaded on Al2O3 base. It was prepared by traditional liquid impregnation -hydrogen reduction methods with loading a series of Ni content. And then through static balance experiments, dynamic balance experiments and dynamic experiments, catalytic properties have been investigated. The obtained experimental results will provide useful data for optimizing the operation parameters and exchange performance in the future VPCE device.This thesis is structured into four parts:1. I choose cheap Ni as active metal, Al2O3 as base material, using the impregnation-liquid-reduction method to acquire a series of structured ceramic catalyst and particle catalyst. Through the SEM and XRD results, we can conclude the catalyst is simple in composition which only consists substrate material and active pure metal in close combination.2. I designed and constructed an entire balance experiment system which has involved different catalysts with varies activated Ni. I have sysmatically explored the influence of temperature, pressure, reactant ratio on both static balance and dynamic balance. This has verified a good catalytic performance for the prepared samples. The detail results are shown in following. A slight better catalytic properties was observed in a Ni catalyst with high load rate than that of Pt catalyst with a low concentration. In the case of reaction temperature T= 200?, the deuterium water concentration was decreased from 5.0% to 1.41% via a detritiation process using Ni (mass fraction 10%) catalyst. Nevertheless, such concentration can reach 1.32%using Pt (mass fraction 0.5%) catalyst. In the case of T= 140?, the residual deuterium water after detritiation process becomes 1.33% for Ni while 1.23% for Pt. It was found that the reaction separation factor (a) increases with pressure when the temperature was kept constant. As seen, the a value equals 0.26 0.28,0.40, and 0.42 at pressure P=101,108, 193, and 303 kPa, respectively. The residual concentration of deuterium water increases with reaction temperature, such as 200?(1.37%),170?(1.32%),140?(1.27%),110? (1.19%). The influence of feed ratio on the results for the final balance the export gas deuterium concentration from the high order what is 4:1,3:1,2:1,1:1,1:2 and 1:3,1:4. For application, the input reactant content depends on the cost and tail gas concentration required to choose the appropriate. At the end, it was seen that the used catalysts are quite stable in different temperature conditions and also the used system was reliable and stable, which is attested by the repeatability of experiment results.3. A set of counter-current type VPCE process device was designed and constructed. It adopts several kinds of catalyst for the study on its catalytic performance and calculation of VPCE process parameters. The obtained results show that deuterium concentration of outlet of the feed ratio on the reaction has large influence. The smaller the hydrogen flow rate, the higher concentration of deuterium output. When the initial deuterium water concentration was 5%, hydrogen and deuterium water feed ratio of 0.2 L/min:64 ml/h,1 L/min:64 ml/h and 2 L/min:64 ml/h, the final balance is 1.63%,1.3% and 1%, respectively. The final deuterium concentration increases with temperature. This facilitates a restructuring isotope substitution from the liquid phase, which achieves the goal of isotopic exchange. When hydrogen and deuterium water feed is 1 L/min:32 mL/h,2 L/min:64 mL/h,3 L/min:96 mL/h and 4 L/min: 128 mL/h, the former two results is 1.08% of residual deuterium water. For the latter two, because of the large flow, the reaction temperature cannot ascend, while set at 100?, the residual deuterium water significantly decreases from 0.92% and 0.98% to 1.08%. When Ni catalyst was fully loaded, an additional Pt does not help to improve catalytic performance. At the same experimental conditions, the results figured out that the residual deuterium water is about 1% when the feed hydrogen/deuterium water is 2 L/min:64 mL/h. Therefore, the prepared catalysts have good catalytic properties, which is high competitive in the industrial application.4. In the real technology and process, per uint volume of particles type have higher catalytical efficiency than structured ceramic type in unit time. When 0.11 kg catalyst was loaded, I performed the experiments with various flows amplification experiments. With the increase of the feed rate of hydrogen arithmetic, the overall volumetric mass transfer coefficient Kya value increase in proportion, which has good linearity (R2> 0.993). The ratio of feeding hydrogen and deuterium water is 2L/min than 64 mL/h, Kya value is 0.818 m3·s-1·m-3 of Ni-loaded particle type catalyst (mass fraction 11.5%), higher than the value of 0.340 m3·s-1·m-3 of Ni-loaded (mass fraction 6%) structured ceramics.To conclude, this work has demonstrated the feasibility of catalytic exchange via the promising Ni catalysts in the hydrogen isotope and water. I have investigated in detail the effect of temperature, pressure and feed ratio on reaction process. The technology parameter of VPCE has been calculated, which can provide useful data for a practical application. |
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