| Ethyl acetate(EA) is a very important organic chemical raw materials and one of environment friendly solvents. EA is mainly used in cosmetics, paints, adhesive, Pharmaceuticals in the field of industrial production. Recently, as the demand of EA in the world increase noticeably, the production of EA in our country develop rapidly, the output is the maximum in the world. The esterification of acetic acid with ethanol is the main synthesis method of EA and this method is widely used in Chinese industry. The sulfuric acid is always employed as catalyst in this process, which brings some severe problems, such as equipment corrosion, environment pollution. In response to the purpose of environment friendiness, the research of improving industrial esterification process has be focused on searching for a gree catalyst which is non-toxic, free of environment pollution and novel esterification catalytic activity.Compared with the traditional acid catalyst, the solid acid catalyst has low productin costs, high catalytic activity and stability, simple separation and recovery, zero corrosion to equipment, no pollution to environment, then shows a broad pratical application prospects. In this paper, we systematically studied the catalytic activity of H3PO4/C and the application of the H3PO4/C in the synthesis of EA, respectively.Firstly, we systematically investigated the effects of different experimental conditions to catalytic activity, including catalyst carrier, the grafts, active component dosage, calcination temperature. The experimental results showed that catalyst is the very economic and suitable for industrial production, when it was prepared under the condition of core activated carbon as carrier, A as grafts, phosphoric acid as active component and the grafts loading ratio of0.2, the phosphoric acid loading ratio of0.4. In the application of esterification, the yield of EA can be reach to84.65%, the conversion of ethanol can be high to82.15%. The catalyst was characterized by XRD, nitrogen adsorption, the results showed that SiP2O7was generated in the preparation process of catalyst. With the increase of catalyst loadings, its surface area and pore volume gradually decreased. The content of P in the esterification products was analyzed by ICP, the results showed that the content of P was0.2537mg/L, the leakage of phosphoric acid was0.036%, it indicates the stability of catalyst was perfect.Secondly, we subsequently inspected the effects of reaction conditions on the yield of EA, including ethanol/acetic acid molar ratio, the reaction temperature and the mass space velocity. The obtained results showed that the catalyst exhibited the best catalytic performance when the molar ratio of ethanol to acetic acid of1:1.1, the reaction temperature of120℃, and the lower of space velocity, the higher of the yield of EA.Finally, on the base of previous work, we investigated the catalyst stability and the effects of feeding method on esterification, and further compared the catalytic activity of H3PO4/C with β zeolite and HPW/C. The experimental result indicated that the phosphoric acid supported on activated carbon catalyst showed good catalytic activity in the100h reaction process, and the method of down-feed was better than up-feed. In the process of down-feed, the yield of EA can be reach to89.6%, which is much higher than that (86.5%) in the process of up-feed. The catalytic activity comparison result showed that the H3PO4/C catalyst is more suitable for industrial production of EA when considering to the production costs and separation process. |
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