高温水蒸汽对铬磷催化剂性能的影响

研究了铭磷催化剂的高温水蒸汽处理对其性能产生的影响。处理温度500℃,时间1—60小时。所采用的方法包括活性评价、比色分析,扫描电镜和顺磁共振等。结果表明,在水蒸汽处理22小时前,异戊二烯的收率无明显变化,选择性有所上升,随着处理时间的延长,异戊二烯的收率和选择性均有下降趋势;反应的“诱导期”缩短了;Cr~(3+)、磷的含量及催化剂的比表面无明显差异,积炭量减少,催化剂的晶粒形态也发生了一些变化。

Effect of Superheated Steam on Properties of Chromium Oxide-Phosphoric Acid-Silica Gel Catalyst

The effects of superheated steam pretreatment of chromium oxide-phosphoricacid-silica gel catalyst on its properties were studied.It was pretreated at 500℃for 1 to 60 hours.The methods used involved catalytic activity evaluation,colorimetric analysis,scanning electron microscopy and electron paramagneticresonance,etc.The results showed that the yield of isoprene had no remarkablechange and selectivity of isoprene increased slightly on pretreating up to 22hrs;and then both yield and selectivity decreased with increasing pretreatmenttime.The induction period for the condensation reaction was shortened.No apparentdifferences were observed in Cr~(3+) and phosphorous contents and specific surfacearea of the catalyst.The amount of coke deposited on the catalyst decreased andsome changes in morphology of catalyst crystals were observed.