改性Pt/HY分子筛催化剂的正庚烷临氢异构化反应性能研究

The Stduy of N-heptane Hydroisomerization over Modified-Pt/HY Zeolite Catalysts

采用机械混合法 ,利用ZrO2 和WOX/ZrO2 对Pt/HY分子筛进行了改性 ,考察了改性催化剂Pt/Zr-HY和Pt/WZr-HY上的正庚烷临氢异构化反应性能 ,探讨了改性催化剂影响催化反应活性和异构化选择性的原因。结果表明 ,改性后的Pt/HY催化剂 ,在反应活性下降的同时 ,异构化选择性显著提高 ,且异构化产物向裂解产物的转化温度明显提高 ,其中Pt/WZr-HY催化剂的这一效果尤为显著。但改性并不改变反应历程。同时改性也使HY的酸量明显减少 ,酸强度改变 。

Pt/HY zeolite was modified by ZrO 2 and WOx/ZrO 2 using physical mixing method,and skeletal hydroisomerization of n-heptane was studied over Pt/HY and so-modified catalysts. The change of conversion and isomerization selectivity due to ZrO 2 and WOx/ZrO 2 modification was then discussed.It was found that the modification resulted in the suppression of n-heptane conversion,but a great increase of selectivity to isomer products.Moreover,the transformation temperature from isomer products to cracking ones was markedly enhanced,especially for Pt/WZr-HY.The modification also decreased the acidity and changed the acid strength,which would affect the isomerization yield.The more the number of acid sites,the higher the isomerization conversion.As a result,n-heptane was converted on three catalysts via the conventional bimolecular reaction mechanism.