Vinyl Acetate Synthesis Catalyst Carrier Activated Carbon Regeneration Of New Technologies

Vinyl acetate monomer is an important chemical intermediate utilised in the production of a variety of different paints, adhesives and surface coatings. Vinyl acetate is mainly produced industrially via the gas phase acetoxylation of acetylene over activated carbon-based catalysts. Its activation vanished after a period of time result in the samples being abandoned. The exhausted catalyst would bring out resource waste and environment pollution. This dissertation presents a new method for disposal of exhausted catalyst, which aims to promote comprehensive utilization of resources and urban environment, implement circuit economy and cleaner production,and achieve stainable development of society, economy and environment.The purpose of this dissertation aims to regenerate exhausted activated carbon-based catalyst using in vinyl acetate production process, in which zinc element was extracted. On the base of reviewing the development of progress in activated carbon regeneration in detail, four regeneration techniques by different activation method that include water vapor activation with electric furnace and microvave as heating agent, carbon dioxide activation in the same heating agent have been studied,and the optimum conditions were obtained through experimental investigation. The adsorption isotherms of the activated carbons which obtained from optimum conditions were determined. The pore structures of samples were analyzed by DA equation, HK equation, BJH method and DFT theoretic. In additional, the microstructures of exhausted activated carbon-catalyst, spent activated carbon after extraction of zinc and activated carbon product were characterized with the help of SEM. Furthermore, the regeneration techniques have been compared combining with the experimental results.The factors involving the influence on the properties of activated carbon, such as activation temperature, microwave irradiation power, activation time and the flow rate of water vapor, have been studied via orthogonal experiments while the activation agent is water vopor. The optimum condition for traditional heating has been obtained as follows: activation temperature is 1000℃ while activation time 90min with the flow rate of water vapor being 3.95g/min. Thus, the experimental results have shown thatthe yield of the activated carbon was 62.86 % when the adsoption value of iodine adsorption, methylene blue adsorption, acetic acid adsorption reached 1181.1 mg/g, 16 mL/ 0.1 g, 590.77mg/g with the surface area 1308.13m2/g. When the heating resource changes to microwave, the optimum condition is microwave power 700W, activation time 40min with the flow rate of water vapor being 2.03g/min. The iodine adsorption, methylene blue adsorption, acetic acid adsorption, surface area and yield of the activated carbon regenerated under above condition are 1193.85mg/g, 19 mL/O.lg, 571.32mg/g, 1547.74m2/g, 65.36%, respectively.When the activation agent is carbon dioxide, the regeneration process have been studied via conditional experiments. The optimum condition for traditional heating method has been obtained as follows: activation temperature 1000 °C, activation time 100 min and the flow rate of carbon dioxide is 0.5m3/h. The iodine adsorption, methylene blue adsorption, acetic acid adsorption, surface area and yield of the activated carbon regenerated in optimum condition are 1091.33mg/g, 14mL/0.1g, 518.30mg/g, 1178.28m2/g and 80.33%. Futhermore, the optimum condition for microwave heating method is microwave power 700W, activation time 25min and the flow rate of water vapor 0.2m3/h. The iodine adsorption, methylene blue adsorption, acetic acid adsorption, surface area and yield of the activated carbon regenerated under above condition are 1158.02mg/g, 16mL/0.1g, 564.43mg/g, 1254.51m2/g and 74.19%, respectively.The results show that the four regeneration techniques are feasible for regeneration of activated carbon-based catalyst using in vinyl acetate production.The idion adsorption, methylene blue adsorption of the all samples obtained under optimum conditions achieve the first grade standards in the GB/T13803.1-1999, GB/T13803.2-1999 and GB/T13803.4-1999. The acetic acid adsorption of the samples regenerated by water vapor achieved the A grade in GB/T13803.5-1999. When the activation agent is carbon dioxide, its acetic acid adsorption achieved the B grade in GB/T13803.5-1999.The pore size distribution carves show that the misopores content of the activated carbon prepared by microwave heating is more than that by conventional heating using the same activation agent. In the same heating resource, the mesopores content of the activated carbon obtained by water vapor activating are more than that by carbondioxide.Through SEM pic, many adsorbent can be observed on the surface of the xhausted activated carbon-catalyst, but the adsorbent died away after extraction of zinc, and the pore strcture formed after regeneration disposal.Through the comparison of different regeneration prosesses, it can be found that the regeneration process by microwave heating and activated by water vapor have many advantages such as short regenerating time and high-quality of product and so on.