硫存在下Beta沸石负载钯催化剂上的芳烃加氢性能研究

A series of beta zeolites supported palladium catalysts were prepared by ion exchange (IE) or incipient wetness impregnation (IWI). The characterizations such as XRD，N2 adsorption and temperatureogrammed desorption（TPD）of ammonia were carried out. Hydrogenation of tetralin was conducted with a continuous-flow fixed bed micro-reactor under 4 MPa, 270 ℃，WHSV 16 h－1 and 100 mg/kg S (thiophene as S source). It is found that catalytic behaviours of the supported Pd catalysts depend both on the preparation methods and on the properties of supports. For Pd/Beta25，the catalytic activity of the sample prepared via ion exchange (IE for short) is superior to the initial wetness impregnated（IWI for short）one. Among three ion exchanged catalysts, Pd/Beta80(IE) is most active and sulphur tolerant during the whole time on stream. Pd/Beta25(IE) deactivates most rapidly because the conversion of tetralin decreases from the initial 77% to 10% after 8?h. With Pd/Beta60(IE), the corresponding conversion are 60% and 16% respectively. And with Pd/Bera80(IE) those are 75% and 55% respectively. The excellent activity of Pd/Beta80(IE) can be attributed to the carrier's higher strong acidity/weak acidity ratio, especially the presence of more medium strength acid sites and the mesopores structure. Besides，the addition of alumina to Pd/Beta25 is favourable to improving its catalytic activity.