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Graphical abstract Highlights • Supported-ionic-liquid-phases as stabilizer of Pd complex active phase. • Different Pd loadings were screened to identify an optimized Pd-based supported-ionic-liquid-phase catalyst. • The catalyst showed superior catalytic activity for acetylene hydrochlorination. • The catalyst displayed stable performance after running for 500 h. • The enhanced catalytic stability may attribute to the confinement of Pd complex. Abstract Vinyl chloride monomer (VCM) is an important platform molecule for the manufacture of polyvinyl chloride (PVC) via the direct hydrochlorination route from acetylene. However it is plagued by the toxicity of the mercury chloride (HgCl 2) catalyst. Here we show that a 0.5Pd-10IL/AC catalyst, working as an environmentally friendly and highly efficient catalyst in supported-ionic-liquid-phase (SILP) system, is an plausible alternative for the commercially used HgCl 2 catalyst for acetylene hydrochlorination. It performs higher activity and more stable conversion than ionic liquid (IL)-free 0.5Pd/AC catalyst during a 10 h reaction. Furthermore, the low-loading 0.15Pd-10IL/AC catalyst demonstrates a stable catalytic performance with a negligible loss of C 2 H 2 conversion after 500 h under typical industrial reaction conditions. After careful characterization of the catalysts and additional catalytic tests, we ascribe the IL influence on the activity and stability of the catalysts to the stabilization and dispersion of active Pd species in the IL layer, the possible coordination of the IL to the Pd atoms, and the confinement of Pd complexes within the pores supports. This efficient and stable non-mercury catalyst provides an opportunity for green route to large-scale vinyl chloride production. [ABSTRACT FROM AUTHOR]