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Skeletal isomerization of n-butane to isobutane has been studied with a flow reactor, mainly at 573 K, over caesium hydrogen salts of 12-tungstophosphoric acid (trihydrogen phosphododecatungstate), Cs,H,-,PW, 2 0 4 0 .The activity was highly dependent on the caesium content, being a maximum for x = 2.5 where the number of acid sites on t h e surface was greatest. The initial rate was first order with respect to the butane pressure (ca. 0.05-0.5 atm) at both 423 and 573 K on CS~~~H,~,PW~~O~,. CS~.~H,.,PW,~O,, was found to be much more active and selective (83% cf. 60%) than S042-/Zr02 at the steady state at 573 K. H-ZSM-5 showed a higher activity than Cs,.,H0.,PW, 2 0 4 0 and S042-/Zr02 but t h e selectivity was only 14%. Cs2.,Hoa5PW, 2040 is a promising catalyst for this reaction and the low deactivation of CS~~~H,~,PW,~~,, is probably responsible for the high catalytic

A salt of H3PW12O40, Cs2.5H0.5PW12O40, catalyzed efficiently the skeletal isomerization of n-butane to isobutane at 300 °C. The activity and selectivity were much higher than those of SO22−/ZrO2. H-ZSM-5 was more active than Cs2.5H0.5PW12O40, but the selectivity was very low.

A solid superacid, Cs2.5H0.5PW12O40, catalyzed the alkylation of isobutane with butenes at room temperature. Cs2.5H0.5PW12O40 was much more active than SO42−/ZrO2, a well-known solid superacid, and was highly selective.

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