Effect of various g-C3N4 precursors on the catalytic performance of alkylorganotin-based catalysts in acetylene hydrochlorination.

Yibo Wu,Zhiping Lv,Jianwei Xue,Fuxiang Li

doi:10.3906/kim-1909-64

Yibo Wu, Zhiping Lv + Show 2 more

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https://doi.org/10.3906/kim-1909-64

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Abstract

A series of alkylorganotin-based catalysts (Sn-g-C3N4 /AC) was prepared by wet impregnation in ethanol using different g-C3N4 precursors and alkylorganotin compounds. The structure, texture, surface composition, and adsorption properties of the as-prepared catalysts were extensively characterized. Then, the obtained samples were evaluated for their catalytic performance in hydrochlorination of acetylene. The results provided by the X-ray photoelectron spectroscopy, acetylene temperature-programmed desorption, and HCl adsorption confirmed the nature of the active sites (i.e. Sn-Nx) involved in the reactant adsorption, and hence in the improved catalytic performance. These active sites were also related to the improved lifetime of alkylorganotin-based catalysts in the hydrochlorination of acetylene. At a constant reaction temperature of 200 °C with an acetylene gas hourly space velocity (C2H2 -GHSV) of 30 h-1 , Sn-g1 -C3N4 /AC-550 exhibited the highest acetylene conversion (~98.0%) and selectivity toward the vinyl chloride monomer (>98.0%). From the catalytic test results, it was reasonably concluded that the hexamethylenetetramine is the most suitable N precursor, as compared to the dicyandiamide and urea, to prepare high-performance catalysts. From the BET specific surface area of fresh and used catalysts, it was suggested that, in contrast to dicyandiamide and urea, hexamethylenetetramine could delay the deposition of coke on alkylorganotin-based catalysts, which is reflected by the extended lifetime.

Highlights

Owing to the widespread applications of polyvinyl chloride (PVC) in all human activities, there is an increased demand for vinyl chloride monomer (VCM) as precursor for PVC manufacture [1,2]
The results indicated that hexamethylenetetramine is the best g-C 3 N 4 precursor as Sn-N X in alkylorganotin serves as catalytically active sites
According to the previous reports [33,34,37], the hexamethylenetetramine, dicyandiamide and urea were calcinated at 550 °C for 4 h under nitrogen atmosphere to successfully prepare g-C 3 N 4

Summary

Introduction

Owing to the widespread applications of polyvinyl chloride (PVC) in all human activities, there is an increased demand for vinyl chloride monomer (VCM) as precursor for PVC manufacture [1,2]. Carbon-supported tin catalysts with a high catalytic performance [11,12,13,14] have attracted little attention compared to copper-based catalysts [15,16,17,18,19,20]. Deng et al [12] have used a trimetallic supported catalyst (SnCl 2 -BiCl 3 -CuCl/AC) for the hydrochlorination of acetylene and reported that the deactivation of SnCl 2 -BiCl 3 -CuCl/AC is mainly attributed to the loss of tin(IV) chloride. The Dai’s group has investigated the catalytic performance of g-C 3 N 4 /AC for acetylene hydrochlorination and reported that the nitrogen enrichment of catalysts can promote the adsorption of hydrogen chloride and significantly increase the activity of this metal-free catalyst [21]. The results indicated that hexamethylenetetramine is the best g-C 3 N 4 precursor as Sn-N X in alkylorganotin serves as catalytically active sites

Results and discussion

Conclusions

Materials and methods