The liquid phase ring-opening of octamethylcy-clotetrasiloxane (D

4

) was investigated over Pt-H

2

SO

4

/Zrmontmorillonite catalyst. Montmorillonite (Mt)

Zr-Mt

H

2

SO

4

/Mt

H

2

SO

4

/Zr-Mt and Pt-H

2

SO

4

/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence

X-ray diffraction

nitrogen adsorption-desorption

NH

3

-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst

Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D

4

polymethylhydrosiloxane (D

4

H

) and hexamethyldisiloxane (MM) to low-hydro silicone oil. Relative to Zr-Mt

the acidity of H

2

SO

4

/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D

4

conversion and yield of low-hydro silicone oil. To enhance the stability of H

2

SO

4

/Zr-Mt catalyst

a small amount of metals (Pt) was doped. The nitrogen adsor

ption-desorption results indicated that pore textural parameters of the Pt-H

2

SO

4

/Zr-Mt had not changed with larger specific surface area. Compared with H

2

SO

4

/Zr-Mt

the total acidity of Pt-H

2

SO

4

-Zr/Mt catalyst retained

but the content of the Brønsted acid increased and the content of the Lewis acid decreased. The Pt-H

2

SO

4

-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization

the yield of low-hydro silicone oil decreased from 93% to 42% over H

2

SO

4

/Zr-Mt catalyst

while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H

2

SO

4

/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H

2

SO

4

/Zr-Mt catalyst was detected. Furthermore

Pt-H

2

SO

4

/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D

4

D

4

H

and MM to low-hydro silicone oil.