阴离子对Zn/Hβ催化剂积碳行为的影响

摘要

The effect of different anions on coke deposition of Zn/Hβ catalysts in reaction of ethanol to propylene was studied in a fixed bed reactor.In this work,the physicochemical properties of these catalysts were characterized by infrared spectroscopy (FT-IR),temperature-programmed oxidation (TPO),powder X-ray diffraction (XRD),programmed desorption of ammonia (NH3-TPD) and N2 isotherm adsorption-desorption (BET).Based on the obtained results,the influences of coke on these catalysts were discussed.The main results show as follows:the coke on Zn/Hβ catalysts might be consisted of aromatic hydrocarbon and aliphatic hydrocarbon;the weak acid sites of Zn/Hβ catalysts and 16％ Zn/Hβ-Ac catalysts might be responsible for the production of coke,but the strong acid sites of 16％ Zn/Hβ-S,16％ Zn/Hβ-C and 16％ Zn/Hβ-N catalysts might be responsible for the production of coke;coke mainly deposited on external surface and microporous mouth.%在固定床反应器中研究了乙醇制丙烯反应中不同阴离子对Zn/Hβ催化剂的积碳行为的影响.采用红外光谱(FT-IR)、氧程序升温氧化(TPO)、X射线衍射(XRD)、氨程序升温脱附(NH3-TPD)及N2等温线吸附-脱附技术(BET)对反应前后催化剂的表面积碳进行了研究.结果表明:在乙醇制丙烯反应中,Zn/Hβ分子筛上的积碳物种主要是芳烃类物种和脂肪烃类物种;Hβ和16％ Zn/Hβ-Ac催化剂的反应活性中心为催化剂表面的弱酸中心,而质量分数16％ Zn/Hβ-S,16％ Zn/Hβ-C,16％ Zn/Hβ-N催化剂的强酸中心是积碳反应的活性中心;Zn/Hβ分子筛上积碳主要沉积在催化剂的外表面和孔口,尤其是微孔孔口.