| Acetylene hydrochlorination mercury-free catalyst and its technology research were hot in current research. Our team had developed an AHC-1 acetylene hydrochlorination mercury-free catalyst. We found that the catalytic activity was affected seriously by the activity carbon in single tube experiment. In face of the problem, acetylene hydrochlorination mercury-free catalyst support research was conducted.First, the performance of surface oxygen groups to the two-component non-mercury AuCl3-CuCl2/C catalyst was studied. It demonstrated that the physical properties of the activated carbons are basically identical before and after different treatments. However, the surface oxygen groups, such as phenol and carboxylic, were increased after oxidizing by HNO3 and decreased in the order of carboxyl, phenol and carbonyl after calcing in different temperature. Taking the above activated carbons as the support, two-component catalysts of AuCl3-CuCl2 was prepared by impregnation method. And the catalysts were evaluated by the acetylene hydrochlorination. The results show that the acetylene conversion rate of the catalysts, which were prepared with the carrier of original activated carbon, pre-treated by HNO3 oxidation and calcined in 500℃ for 1h, can reach above 96%,98% and 90%, respectively. And they have good reaction stability in 10h. While the acetylene conversion rate dropped sharply to around 30%after 4h for the other two catalysts, whose carriers were calcined in 700℃ and 1000℃.In addition, the analysis results by BET, H2-TPR and SEM showed that the BET specific surface area decreases mostly, carbon deposition is more serious and active component dispersion is poorer. It proved that the surface oxygen groups, especially for the hydroxyl group, plays an important role in promoting the dispersion of Au, enhancing the stability and reducing the carbon deposition.Secondly, the alumina support produced by Gongyi Baolai water processing factory was chosen as the the new support. The effect of channel structure and the specific surface area, acidic and alkaline site on the surface of the support was analysied. It was found that the alkaline site on the surface of the support, had the greatest influence on the catalytic performance. The stronger alkaline, the more alkaline center, the better performance of the catalyst. The acetylene conversion rate can reach 97.2%, vinyl chloride selectivity can reach more than 99% with the selected optimal carrier.Then, the catalyst deactivation and regeneration method was investigated. The mainly catalyst deactivation was carbon deposition. The surface carbon deposition can be burned out after roasting 1 h under 500 ℃ in the air atmosphere. The acetylene conversion rate were 96% and 92% respectively, vinyl chloride selectivity can reach above 98% for the first and secondary regeneration catalyst.Finally, the stability of the catalysts was investigated. Screening BiCl3 as the new cocatalyst components, the optimal weight ratio of Au/Bi was 0.1/5. At the reaction conditions of T= 150 ℃, P= 0.1 MPa, V (HC1):V (C2H2)= 1.1:1, the GHSV= 120 h-1, the acetylene conversion rate can reache up to 96% and the vinyl chloride selectivity can reach more than 99%. The catalyst life increased from 1 h to 12 h. It can effectively reduce the load of Au from 1.0% reported for by most literatures to 0.1% with the mesoporous alumina as the support. The deactivation ways was mainly carbon inactivation for the Au-Bi/ Al2O3 catalyst. The addition of Bi can effectively inhibit the reduction of the Au3+ in the preparation, storage and reaction. And carbon deposition can be suppressed to a certain extent. Carbon deposition structure changed form sheets to filamentous structure. |
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