| LAB are very important industrial chemicals used in the manufacture of detergents, they are mixtures of C9-C14 alkyl benzenes synthesized by the alkylation of benzene with mixed linear olefins usually using anhydrous HF as catalyst. Due to the hazardous nature of anhydrous HF, efforts are made to find environmentally safer catalysts like solid acid catalyst. Now the only commercial process using a solid acid catalyst is UOP's Detal process industrialized in 1995. As the deactivation rate of solid acid catalysts is rather fast, two fixed bed reactors are used in this technology to be switched to conduct the operation of reaction and regeneration alternatively, 24 hours being a switch cycle. Yet it is inconvenient for this operation to be used industrially because of its discontinuity. Our group has developed a new process for the synthesis of LAB using modified Hβ zeolite as catalysts, which overcomes the shortages of HF process and, furthermore, detergents produced from the new process are more easily biodegraded than those from HF and Detal Processes. However, the modified Hβ zeolite catalyst also deactivates easily as other solid catalysts, Fortunately, the deactivation agents can readily be desorbed from the catalyst by washing the catalyst with hot benzene and modified Hβ zeolite catalyst can be regenerated repeatedly. The purpose of this study is to develop a new technological process, which can overcome the above shortages of HF process and Detal process, for the renovation of LAB production technology.In this dissertation, the mechanisms of deactivation and regeneration of Hβ zeolite are investigated, the catalyst is modified by HF solution and a novel coupled circulating moving bed is proposed for the synthesis of LAB. According a lot of experiments, the following conclusions are obtained:The characterization of the coked catalyst shows that the deactivation of catalysts is caused by a jam of bulkier molecules, which are the alkylbenzenes from both1. reactants and products, so the deactivation cannot be avoided. These bulkier molecules deposit in intracrystalline pores and then in larger pores.2. When the deactivated catalysts are regenerated by hot benzene washing at higher temperature, cracking and cyclization occur and some new species, such as low-carbon aromatic compounds, naphthalene and indane, biphenyl, fused ring compounds, and unsaturated compounds are formed. To increase the yield of LAB, the cracking and cyclization must be minimized, so regeneration temperature cannot be too high. 3. Based on the XRD, BET, FTIR, TPD, element analysis and catalyst longevity testing, it is found that when impregnated by low concentration HF solution, the extra-lattice species and unstable lattice aluminum in Hβ zeolite are dissolved by HF solution, so the specific area, pore volume and catalyst longevity increase; however, with the increase of HF concentration, both Hβ zeolite and the extra-lattice species are dissolved and form AlF3 or other fluorinated compounds which deposit in the catalyst, so the specific area, pore volume and catalyst longevity decrease. To modify catalyst using HF solution, the proper concentration is about 2%. 4. According to the process characteristics, a novel coupled circulating moving bed reactor is proposed for the synthesis of LAB catalysed by Hβ zeolite catalyst. In the reactor, a novel particle transport and regulation system is developed, which includes a jet pump and auxiliary regulation liquids. Furthermore, a model describing particle transportation is established. The experiments show that the system can be effectively used to transport and regulate particles, and the downward auxiliary liquid is the best one for regulating particle circulation rate.5. The mathematical models of stress distribution and states of standpipe are established based on the particulate solid mechanics. The calculation shows that the highest stress regions are at the bottoms of regeneration chamber and standpipe. To decrease the wear and break of the catalyst...
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