Ni-Ni₃P/SiO₂ Catalyst for Highly Selective Production of Silicon Tetrachloride via Silicon Hydrochlorination

Abstract

SiHCl3 (TCS) and SiCl4 (STC), important chlorosilanes in the silicon industry, are currently produced by noncatalytic silicon hydrochlorination with a selectivity of 85% for TCS and 15% for STC approximately. It is a significant challenge to selectively produce TCS and STC with the desired ratio in one reactor to realize flexible manufacturing that meets the periodic market demands. In the present work, we develop a novel Ni-Ni3P/SiO2 catalyst using a simple reduction synthesis method to produce STC selectively in Si hydrochlorination. The catalyst performance is evaluated under different industrial operating conditions. It shows that the Ni-Ni3P/SiO2 catalyst exhibits a selectivity higher than 90% for STC and a selectivity of <10% for TCS under the optimal conditions. The calculations based on the density functional theory show that P-modified Ni-based catalysts promote the breakage of HCl bonds and make the product favor STC instead of TCS. Therefore, it is possible to realize flexible manufacture of TCS and STC in one reactor by combining the CuO-based catalysts reported in our previous work to enhance TCS production and the Ni-Ni3P/SiO2 catalyst developed in this work to promote STC production.

Thermodynamic Analysis of the Key Reactions in Synthesizing Inorganic Silicon Compounds or Products

“…However, it should be noted that even at a very high temperature of 1000 °C, the conversion of STC (or yield of TCS) can reach only 16.5% (Figure a), suggesting STC is the thermodynamically more favorable product. Increasing pressure will not affect the mutual transformation between the STC and TCS (Figure b), matching well with the calculation of a previous report …”

“…In other words, STC is thermodynamically most favorable, while SiH 4 is least favorable, and the hydrogenation of Si cannot produce the latter. The optimal reaction temperature to produce TCS should be less than 350 °C from a thermodynamic point of view, which is similar to the findings of existing studies. , Our previous experimental results indicated that the conversion of Si could reach 90.0% after 8 h of reaction at 300–400 °C without a catalyst, which is generally consistent with the above calculation results.…”

“…The preparation and applications of these silicon compounds have been intensively studied, and our previous work also investigated catalysts for reactions related to inorganic silicon compounds. − Thermodynamic analysis of the related thermal reactions can provide an essential reference for thermodynamic equilibrium limits and selection of suitable reaction conditions. However, there are very few corresponding thermodynamic studies regarding inorganic silicon compounds.…”

High‐Index Faceted Cu2O@CuO Mesocrystals Act as Efficient Catalyst for Si Hydrochlorination to Trichlorosilane

“…In the O 1s XPS spectrum (Figure 2a), a main peak of the surface lattice oxygen (529.5 eV, denoted as O latt ) [31] and a weak peak corresponding to the adsorbed hydroxyl groups (531.3 eV, denoted as O ads ) [32] are detected. The Cu 2p XPS peak with bind-ing energy at 933.4 and 953.3 eV are assigned to the Cu 2p 3/2 and Cu 2p 1/2 states of Cu 2+ , [25] respectively, together with the appearance of two obvious satellite peaks (denoted as Sat.) at 942.8 and 962.0 eV (Figure 2b), indicating the predominance of Cu 2+ on the surface of Cu 2 O@CuO HIMCs.…”

“…[24] In the industry, TCS is currently manufactured via a noncatalytic hydrochlorination of metallurgical Si at temperatures above 350 °C. [25] This process generates a large amount of by-product silicon tetrachloride (SiCl 4 or STC), and thus improving the TCS selectivity and yield to reduce its manufacturing cost is highly demanded. [9,[26][27][28] This work demonstrates that Cu 2 O@CuO HIMCs can significantly enhance the Si conversion and TCS selectivity in Si hydrochlorination compared to the catalysts with flat surfaces and nanostructured forms.…”