H2SO4, acid strength

HS04 and H3PO4 are very similar in acid strength Both are much weaker than H2SO4 which IS a strong acid... 

The spent acid strength is maintained at about 90 wt% H2SO4. The molar isobutane/alkene feed ratio ranges from 7 1 to 10 1. Typical operating alkene space velocities (LHSV) range from 0.2 to 0.6 h-1 (corresponding to WHSVs from 0.06 to 0.19 h 1). The optimum reaction temperatures range from 279 to 283 K, but some units are operated at temperatures up to 291 K. 

The activities of heteropolyacids for the decomposition of isobutyl propionate were found to be 60-100 times higher than those H2SO4 and p-toluenesulfonic acid 63). The activity increases with increasing acid strength of heteropolyacids. 

Benzene was alkylated with crude propylene, using H2SO4 of strength from 75 to 97%. The spent acid was recycled in part. With equal moles of benzene and propylene, 25% by weight of acid based on benzene gave 35% isopropyl and 35% polyisopropyl benzene, while 100% acid gave 40% isopropyl and 50% polyisopropyl benzene. With 0.5 mole propylene per mole benzene, all the propylene was consumed and the ratio of mono- to polypropyl benzenes was independent of the acid ratio. 

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