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Modified 10 yuan ring pore zeolite catalyst shape-selective toluene disproportionation

Author: LiangJinHua
Tutor: WangJun
School: Nanjing University of Technology
Course: Chemical processes
Keywords: ZSM-5 MCM-22 Toluene disproportionation Silicon modified Chemical liquid deposition Shape-selective catalysis
CLC: O643.3
Type: Master's thesis
Year: 2004
Downloads: 142
Quote: 2
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Abstract


Paraxylene production of terephthalic acid is the main raw material, with the polyester industry's rapid growth in demand for paraxylene will be more vigorous. Toluene with high selectivity by the shape-selective disproportionation catalyst paraxylene production technology can effectively expand the source of p-xylene, is a highly competitive process route. This paper first analyzes the paraxylene production status and prospects, and the development of shape-selective toluene disproportionation technical significance; overview of the current selective toluene disproportionation catalyst of industrial technology and research status, focused on enhancing the shape-selective ZSM-5 catalyst of various modified method, in which the outer surface of the silicone non-passivated zeolite shape selectivity and narrow orifice diameter acidic sites for the purpose of chemical liquid deposition method most industrial applications and research value. Paper goes on to HZSM-5 catalyst active component, influences of different binder, the binder content, the type of silicon deposition agents, solvent deposition, deposition dosage, deposition time and deposition times, different treatment acid treatment, and water temperature, The modified catalyst activity and selectivity to p-xylene. In this highly selective catalyst preparation further investigated the stability of the catalyst, a detailed study of the process conditions on the conversion of toluene and p-xylene selectivity, such as liquid space velocity (WHSV), the reaction temperature, the reaction pressure, hydrogen to hydrocarbon ratio and get a suitable reaction conditions. Preliminary final thesis explores new 10-membered ring zeolite MCM-22 in the opening shape-selective toluene disproportionation reaction performance and the use of chemical liquid phase deposition method for silicon modified MCM-22 investigated the catalytic properties of the modified. Through the above experiments the following results: First, the chemical liquid deposition modified HZSM-5 catalyst study examines alumina, silica sol, Yang Gan soil and other chemical liquid deposition of binder on the effect of silicon modified , found that the binder and the soil for the sheep Gan content of 20%, the modified catalysts in toluene conversion of both higher have high selectivity. Studied the deposition agent type on the effect of modified screened suitable deposition agent. Studies have shown that deposition conditions, non-polar solvents favor deposition reaction, the experiment cyclohexane as a solvent is preferred. Little effect on the selectivity of deposition time ,7-10 h can be. Repeated deposition, increasing the dose deposition selectivity can improve the bit, and there is an optimum deposition (0.3-0.4 ml / gcat). Acid treatment increases the activity of the catalyst formed, oxalic acid and citric acid can significantly enhance the deposition of the catalyst modification effect. Silicon deposition agent oxalic acid treated catalyst for the second silicon modified, each deposition quantity was 0.4 ml / gcat, the toluene disproportionation I lt; WP = 4 gt; Abstract conversion rate of 26.5%, p-xylene selectivity reached 91.7%. On this basis, explores the 100% atmospheric water vapor treatment on the catalytic activity and selectivity results show that under 300-350 ℃ for 2 h, the toluene conversion was 23.1%, up 97.2% p-xylene selectivity. Second, the reaction conditions of 200 h of a toluene disproportionation catalyst stability test shows that a stable conversion rate (gt; 23.0%) and stable selectivity (96%). Study process conditions, high pressure, low temperature, low liquid space velocity can improve the yield of p-xylene, at a reaction temperature 420 ℃, pressure of 2.5 MPa, WHSV of 1.5 h-1, H2 / hydrocarbon mole to 2 - 3 under the conditions of 25.8% toluene conversion, selectivity 94.1%, 10.5% p-xylene. Three, HMCM-22 and Modified HMCM-22 toluene disproportionation reaction of the HMCM-22 zeolite on toluene disproportionation over HZSM-5 zeolite has a much higher initial activity, high catalytic activity during the reaction pressure is higher than the activity of low temperature and pressure , low temperature and low pressure in excess of the thermodynamic equilibrium value shows selectivity. HMCM-22 Easy coke deactivated catalyst deactivation reaction temperature slowly. Using oxalic acid treatment can partially eliminate the outer surface acidity, resulting in the same conversion rate can improve the selectivity of p-xylene, three times the silicon deposition, the catalyst activity decreased, but the selectivity of up to 97% on the bit. Shows the modified MCM-22 zeolite has a shape-selective toluene disproportionation potential performance.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic
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