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Study On Performance And Deactivation Of Metal Oxide Catalyst For Benzaldehyde Production From Benzoic Acid

Posted on:2008-12-24Degree:MasterType:Thesis
Country:ChinaCandidate:L LiuFull Text:PDF
GTID:2121360212489140Subject:Industrial Catalysis
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Benzaldehyde is an important kind of aromatic aldehyde in chemical industry as an essential chemical resource to produce aroma chemicals, medicines, plastic additives and cosmetic preservatives. It is quite significant to develop benzaldehyde production nowadays. Thus, a bunch of methods emerge as the times require. It is deemed that the method of hydrogenation from benzoic acid to benzaldehyde, which sprung up in the 1990s, has a bright future because of its accordance with the requirements of green chemical technology.In this work, the mechanics of hydrogenation from benzoic acid to benzaldehyde is employed as a basic theory to guide the primary selection of catalysts. More than 10 catalysts have been studied respectively. The results indicate that none of ZrO2, La2O3, TiO2, V2O5, Bi2O3, PbO, Nb2O5 is fit for the reaction. Then the focus goes on the activity of Mn series, Zn series, and Ce series catalysts which are both inexpensive and easy to prepare. Two kinds of CeO2 which show excellent activity are screened out as the optimum catalysts. Further investigation is taken to find out what the stability of the two catalysts is like.According to the XRD, TG and EA results, the deactivation of CeO2 during redox process can be ascribed mainly to the coke formation. Meanwhile, the average crystallite size increases along with the reaction progresses, which is also responsible for the catalysts' deactivation.Regeneration test has been carried through to eliminate the coke on the catalysts and to lengthen the catalysts' longevity. The deactivated catalyst has been regenerated by being calcined at 500 ℃ in an air environment to eliminate the coke. However, the average crystallite size increases irreversible.In addition, one experiment was done in which under steady-state conditions pulses of water were injected into the feed in order to determine the effect of water on the performance of the catalyst. The water is responsible for a sharp increase of the average crystallite size, which is not helpful to the stability of the catalyst.
Keywords/Search Tags:Benzoic acid, Benzaldehyde, CeO2 catalyst, Activity, Coke, Crystallite size, Regeneration
PDF Full Text Request
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