(602bk) A Green Carbon Supported Au Catalyst for Acetylene Hydrochlorination Into Vinyl-Chloride-Monomers for Polyvinyl Chloride Production

Polyvinyl chloride (PVC), which is a vinyl polymer constructed of repeating vinyl groups (ethenyls) having one of their hydrogens replaced with a chloride group, is the 2^nd most widely produced plastic with a productivity exceed 40 million tons by 2016. PVC is widely used in construction because it is cheap, durable, and easy to assemble. However, the production of the vinyl chloride monomer (VCM) required HgCl₂ catalysts, which costs a lot of environmental pollutions. Developing new cost-effective and non-mercury catalysts and related process is quite crucial for a sustainable society. In this contribution, a novel carbon based Au catalyst (defined as ABC) for acetylene hydrochlorination was developed, which showed advanced activity and life time. Active carbon (AC) with hierarchical pore structure was selected as catalyst support. To increase the interaction between the support and active phase, AC was pre-treated by a mixture of H₂SO₄ and HNO₃ to facilitate the anchoring of active metal nanoparticles. The catalyst was prepared by simple co-impregnation in the solution containing HAuCl₄ (active phase) and chlorides of metal promoters, following by drying under 130 °C for 8 hrs. The morphology and catalytic performances were characterized by SEM, TEM, XPS, TPR. SEM and XPS results indicated that the existence of promoter metals facilitated the dispersion of Au nanoparticles on AC, which increased the initial reaction activity. Besides, the activity of the main active substance Au³⁺ was also improved. Au-only-based catalyst showed the highest activity with 1wt.% Au content (Au atomic weight to AC weight), while the optimized Au weight content can be reduced to below 0.5 wt.% with the addition of metal promoters. Under the condition of acetylene hydrochlorination of 200 °C and 1200 h-1 (Space Velocity, Volume based), the acetylene conversion over 70 % can be achieved and maintained for 10 hrs, which indicated that both the activity and the stability of the catalyst were enhanced. This demonstrated that the carbon based Au catalyst can be a very promising green catalyst for polyvinyl chloride industry.