Effect of steam on the acid strength of H3PW12O40/SiO2 <f>·</f> nH2O and its application in skeletal isomerization of n-butane

The effect of steam on the acid strength of H3PW12O40 (HPW)/SiO2 <f>·</f> nH2O was determined by the Hammett indicators. When the steam content in N2 was 1.6%, the acidity (H0 > −13.7) of HPW/SiO2 <f>·</f> nH2O could be kept for over 10 h at 300 °C, but for only 2 h when steam was lacking. When it was used as a catalyst for skeletal isomerization of n-butane to isobutane at 300 °C, the HPW/SiO2 <f>·</f> nH2O showed stability in the presence of steam (1.6% in feed) better than that without steam, due to a suppression of the loss of crystalline water. [Copyright &y& Elsevier]