Dissertation > Industrial Technology > Chemical Industry > Reagents and the production of pure chemicals > Catalyst ( catalyst )

Deactivation, Regeneration and Reaction Process of Titanium Silicalite Molecular Sieve Catalysts for the Epoxidation of Propylene

Author LiuXueWu
Tutor WangXiangSheng
School Dalian University of Technology
Course Industrial Catalysis
Keywords Titanosilicalite TLC TS-1 Propylene Epoxidation Solvent effect Inactivation Regeneration
Type PhD thesis
Year 2005
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Propylene oxide (PO) is an important organic chemical raw materials, industrial production methods are mainly epichlorohydrin law and co-oxidation. Chlorohydrin equipment corrosion and environmental pollution is serious, co-oxidation equipment investment is huge and being linked products - styrene or tert-butanol market constraints. 1983, Taramasso first reported titanium silicalite (TS-1) synthesis, for the selective oxidation of olefins has opened up a new way. With TS-1 molecular sieve catalyst, propylene and H 2 O 2 reaction of PO, by-product is water, is a highly selective cleaning process. Meanwhile, the method also has high utilization of atomic, mild reaction conditions and simple technology, is currently the most promising PO production technologies. In this thesis, TS-1 catalyzed epoxidation of propylene solvent effect were discussed, both single-tube experiments inactivation thin TS-1 catalyst as the research object, the system studied by thin-layer TS-1 catalyst deactivation and regeneration. Main contents are as follows: First, the use of the product impregnation method to study the solvent on the PO impregnated TS-1 Process; systematically investigated different solvents of TS-1 propylene epoxidation performance, and Fourier transform infrared spectroscopy (FT -IR) and thermal gravimetric analysis (TG) catalyst after the reaction by means of physical and chemical properties were characterized. The results showed that: when the absence of solvent, PO on the TS-1 are prone to self-polymerization reaction, the catalytic activity of TS-1 was greater than propylene glycol monomethyl ether (MME) or propylene glycol (PG). Solvent polarity parameters on the PO has a great impact on self-polymerization reaction. In the TS-1 catalytic epoxidation of propylene, solvent or mixture of solvents content of each component and the properties on the catalytic activity of TS-1, PO selectivity and reaction on the catalyst type and content of sediments great impact polar organic solvent empirical parameter E T (30) larger the higher the catalyst activity. Secondly, the inactivation of a single tube experiments thin TS-1 catalyst (DeEPO-4) was investigated using X-ray diffraction (XRD), nuclear magnetic resonance ( 29 Si MAS NMR, 13 C CP / MAS NMR), FT-IR, UV-visible absorption spectroscopy (UV-Vis), thermogravimetry (TG), temperature-programmed mass spectrometry (TPD-MS) and in situ characterization methods such as online chromatography on which were analyzed; while using three-stage reactor, the strip TS-1/SiO 2 catalyst deactivation process is studied. The results showed that, EPO-4 catalyst was significantly lower crystallinity, little change in the specific surface area, pore volume and average pore size. TS-1 inactivation caused by the coke deposits, coke species mainly PG, PO and PO from the homopolymer and MME, PG formation of polymer. Finally, single-tube amplification experiments deactivated catalyst (DeEPO-3, DeEPO-4) as the research object, the system examines the regeneration method for regeneration of the deactivated catalyst performance, characterization methods while using analysis of physical and chemical properties of the regenerated catalyst. The results show that using dilute H 2 O 2 in vivo regeneration, the catalyst activity can be fully restored, but slightly lower PO selectivity at the initial stage; With the increase in frequency of regeneration the catalyst activity can be fully recovered, but gradually decreased PO selectivity, the regenerated catalyst is gradually decreased crystallinity, L acid centers waning. In vitro regeneration, roasting

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