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Alkylation Of Benzene And Propylene In Liquid Cumene Zeolite Catalyst Deactivation

Posted on:2004-11-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:J J BianFull Text:PDF
GTID:1111360095955224Subject:Industrial Catalysis
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Cumene, one of the largest commercial volume derivatives of benzene, is an important intermediate in the production of phenol and acetone (>90%), acetophenone, and a-methylstyrene. The worldwide capacity for cumene topped 10 million metric tons per year, and the growth rate is expected to be 3.8% per year in the next decade. Conventional cumene plants use alumimium chloride and solid phosphoric acid catalysts. However, these catalysts caused corrosion and disposal problems, creating an opportunity for commercialization of cumene processes based on zeolites. Novel zeolite-based cumene processes have been commercialized by Dow/Kellog (dealiminated mordenite), Mobile/Badge (MCM-22), UOP(Q-MAX process used zeolite p) , Enichem(zeolite (3), and CDTech (zeolite Q for alkylation, zeolite Y for transalkylation).BPA, the modified zeolite P catalyst, explored by our group, used for benzene alkylation to synthesize cumene, has been tested in pilot plant where the 1 00kg catalyst loaded , and the BPA showed high activity, high selectivity and long life. The BPA catalyst deactivated after 8000 hours time on stream in the first circle. The deactivated catalyst underwent temperature programmed oxidation to refresh, and the refreshed BPA performed well in 7000 hours time on stream of the second circle.In this dissertation, the effect of reaction conditions on the coking behavior of BPA in a small fixed-bed scale was estimated, followed by the coking deactivation study concerning or the BPA catalysts coked in the small fixed-bed scale both in the accelerated decay where 1.5g catalyst loaded, and in 1000 hours time on stream activity evaluation where 20.0g catalyst loaded, and concerning on BPA catalyst coked in pilot first circle 8000 hours' run and second circle 7000 hours' operation where 100kg catalyst loaded.The coking deactivation study of BPA catalyst was divided into (1) nature of coke, (2) coke distribution on catalyst (in pores of zeolite, on surface of zeolite particles, and in secondary pores of zeolite particles), and (3) coking mechanism and mode of coke formation.13C NMR, FT-IR, UV-Vis, GC-MS, Thermal Gravity and Temperature Programmed Oxidation were applied to detect the coke nature. SEM, N2 physical adsorption, n-hexane/c-hexane adsorption, and coke extraction by N-methyl pyrrodine above 200 ℃ in an autoclave were employed to determine the nature of the coke on zeolite particle surface. XRD, XRF, NH3-TPD, 31P NMR, pyridine/2,6-dimethyl-pyridine adsorption UV-Vis (modified by author), and pyridine adsorption FT-IR were used to explore the change of crystallinity, and acidity between fresh BPA and the coked ones.For the reactor of pilot was installed bypass of the industrial UOP device, the coking behavior of BPA in pilot is similar to that in industry. The commonness and the difference ofBPA coking in lab and in polit can be deduced, and the coking mechanism of BPA can be inferred. Then, accelerated decay was designed for simulating the BPA coking process in pilot, even for predicting the BPA coking way in industry. The ameliorations of TPO regeneration conditions were proposed.Lastly, A new post-synthesis method to prepare Hp from Nap was developed, and the HP made in this way showed a high activity for benzene alkylation to cumene.It can be concluded: (1) In lab, reaction temperature effects the nature of coke, 150℃ ~ 195 ℃, coke shows more character of polyaromatics as temperature higher; The amount of multi-alkylbenzene and polyaromatics increases when benzene to propene mole ratio decreases from 1.5:1 to 1.2:1 as additional propene added, while the amount of polyaromatics decreases when benzene to propene mole ratio decreases from 1.2:1 to 0.9:1, for more multi-alkylbenzene created; The nature and the amount of coke change little when temperature and ratio of benzene to propene fixed, WHSV of propne is 1.02h"1, 2.03h~', and 4.06h-1; and the coke formation speed decreases as time on stream increases.(2) Coke composition: Whether in lab or in pilot, the coke deposited on decayedBP...
Keywords/Search Tags:Benzene, Propene, Alkyltion, Cumene, Zeolite p, Coke, Characterization, Coking mechanism, Reaction conditions, Acidity
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