Synthesis of Dimethyldichlorosilane by Catalytic Disproportionation of Methyltrichlorosilane Over A H₂SO₄ Activated Chinese Bentonite

Abstract

Disproportionation of methyltrichlorosilane (MTS) to produce dimethyldichlorosilane (DMCS) was firstly carried out over a bentonite from Zhejiang province (China) after H₂SO₄ activation. The results demonstrated that the bentonite activated with 30 wt% H₂SO₄ solution exhibited an excellent activity with 92% conversion of MTS and 41% yield of DMCS at 673 K under atmospheric pressure. The catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRD) and N₂ absorption–desorption. The acidic sites of these bentonites were studied by in situ FTIR spectra of pyridine adsorption. It revealed that the coexistence of Lewis (L) and Brønsted (B) acidic sites facilitated the formation of DMCS and reaction temperature played important roles in the disproportionation reaction.

GRAPHICAL ABSTRACT

Keywords:

• Disproportionation
• methyltrichlorosilane
• dimethyldichlorosilane
• bentonite
• acid activation

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 21062013 and 20562007), the Foundation of Educational Department of Jiangxi Province and the Graduate Innovation Foundation of Jiangxi Province (No.YC09A032).

Notes

^aSiO₂ content was calculated according to the contents of other compositions.

^a Volume ratio of liquid : solid was 3.

^b The integral area of d(001) diffraction peak.

^c The samples surface area were calculated using the Brunauer–Emmett–Teller (BET) method based on adsorption data in the partial pressure (P/P ₀) range of 0.05–0.35.

^d The average pore size was obtained from the adsorption data by the Barrett–Joyner–Halenda (BJH) method.