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Study On Low-temperature Removal Of Hydrogen From Chlorine Liquefaction Tail Gas By Ag/Al2O3and Pd/Al2O3Catalyst

Posted on:2015-08-08Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y WangFull Text:PDF
GTID:2181330467987455Subject:Chemical Engineering and Technology
Abstract/Summary:PDF Full Text Request
Chlor-alkali occupy an extremely important position in the national economy, it is not only basic chemical raw materials industry, but also an important pillar industry of inorganic chemical sector. Its main products include caustic soda, chlorine, hydrogen etc., and is widely used in light industry, textile, metallurgy, water treatment, pesticides, building materials, electronics and other fields. Meanwhile, the chlor-alkali industry is also a high-energy industry. Therefore, the process of tail gas purification by removing hydrogen at low-temperature with catalyst and safety using has an important role in achieve clean, safe production in chlor-alkali industry.In this paper, the supported metal catalysts was prepared by impregnation method, the progress and significance of catalytic dehydrogenation were reviewed, and method of chemical analysis about dehydrogenation reaction product of water and hydrogen content is by weight analysis and saturated salt water absorption analysis method, meanwhile, the catalyst reproducibility is also examined. On this basis, we used a self-made reaction vessel (272.5mL) to prepare mixed gas, the volume percentage of the reaction raw material gas were:Cl2(72.83%), O2(9.9%), H2(3.97%), N2(13.3%). Pd/Al2O3and Ag/Al2O3which were prepared by impregnation method were used for the study on low-temperature dehydrogenation of tail chlorine gas. And the structure of the catalysts was characterized by XRD, N2adsorption-desorption analysis and FTIR. And the influence of reduction temperature, reaction temperature, metal loading amount, amount of catalyst, catalyst recycle use times on the reaction was studied. The conclusions are as followings:First, XRD spectra, N2adsorption isotherms and pore size distribution curves of samples show that the features and surface absorption peaks and vibration peaks catalyst Ag/Al2O3and Pd/Al2O3are evident, and the wider diffraction peaks, indicating that the metal palladium and silver on the y-Al2O3well dispersed. FTIR showed that the framework structure of catalysts were obvious. After recycle use seven times, diffraction peak of catalysts were still clearly visible, and there is not an obvious change in the characteristic diffraction peak and surface vibration absorption peak, this indicated that catalysts were stable as catalyst for low-temperature catalytic dehydrogenation in mix tail chlorine gas.Second, experiments show that optimum technological conditions of the Pd/Al2O3and Ag/Al2O3are as following:reduction temperature was250℃and350℃, the reaction temperature is60℃, the metal loading of1%Pd metal Ag loading of2%, catalyst dosage of0.5g. It was found that the catalytic activity of Pd/Al2O3is higher than Ag/Al2O3, the Pd/Al2O3maximum conversion rate of hydroxide were77.12%which were much higher than that of Ag/Al2O3(54.31%). However, the Pd/Al2O3maximum conversion rate of hydrogen chloride reaction was20.26%which were much lower than that of Ag/Al2O3(21.53%). But the conversion rate of hydrogen chloride was always lower than that of hydroxide reaction and the two conversion trend were consistent to each other. The results showed that Pd/Al2O3catalyst had a better performance than Ag/Al2O3catalyst in the reaction of removal of hydrogen from tail gas in low-temperature.
Keywords/Search Tags:tail gas, chemical analysis, supported catalyst, Pd/Al2O3, Ag/Al2O3, low-temperature catalytic dehydrogenation
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