Ru-based catalysts modified in different atmospheres by plasma technology were prepared to catalyze the acetylene hydrochlorination reaction. The (Ru/AC)-N2 (AC = activated carbon) catalyst yielded by the plasma modification of Ru/AC catalyst in N2 atmosphere exhibits the best catalytic performance with a stable C2H2 conversion of 87.2%; a relative increase of 27.1% in C2H2 conversion was achieved compared with that of the untreated Ru/AC catalyst. The results of the analysis revealed that the modification produced a mutual effect between the generated function groups on carrier AC and the active components, which can disperse and yield more active species in the fresh catalysts. These are benefits of enhancing the activity of the catalysts. Moreover, the modification can restrain coke formation and inhibit the loss of active species in the reaction, as well as strengthen the adsorption ability of reactants on the catalysts. These are benefits of improving the catalysts' performance.

A series of Au catalysts were prepared with several representative solvents and evaluated for acetylene hydro chlorination. The results revealed that the activity of the catalyst is closely linked with the intrinsic properties of solvents. The catalytic performance of the catalysts increased with decreasing polarity of the solvents, and superior performance was achieved over the Au-isopropanol/AC catalyst, with a 84% stable conversion under reaction conditions of 180 degrees C and a gas hourly space velocity (GHSV) of 1200 h(-1); relative increases of 700.0% and 483.3%, respectively, in acetylene conversion were achieved compared with that achieved with traditional catalysts prepared with water and aqua regia. The substitution of the highly polar water and aqua regia with weakly polar and volatile alcohols altered the crystallization process of Au nanoparticles (NPs) during their formation. The various edges or defects in the formed multiple-twinned or polycrystalline particles provided new active sites for reactants. The altered solvents may enhance the interaction between the support and the Au species, highly dispersing and anchoring the active species and inhibiting their agglomeration and loss during the reaction. Moreover, the interaction also strengthens the adsorption capacity for reactants of the catalysts, enhancing their catalytic performance. This approach may provide an effective reference for exploring environmentally benign mercury-free catalysts for acetylene hydrochlorination.

A series of catalysts, including Ru/AC, Ф-P-Ru/AC, Ф-P-Ru/AC-HCl, and Ф-P-Ru/AC-HNO3, were prepared and evaluated for the hydrochlorination reaction of acetylene. The test results reveal that the Ф-P-Ru/AC-HNO3 catalyst shows superior catalytic performance with an initial acetylene conversion of 97.2% and a relative increment of 87.0% within 48 h in comparison with that of the traditional RuCl3 catalyst. The substitution of inorganic RuCl3 precursor by organic Ф-P-Ru complex species in the catalysts results in more active species and tends to confine them in the micro-pores; the modification of carbon support by nitric acid in Ф-P-Ru catalyst may produce an interaction between the functional groups on modified support and Ru species, which is favorable to anchor and then reduce the loss of active species during the reaction, further increasing the amount of dominating Ru species, and greatly improving the reactants adsorption ability on the catalysts, thus enhancing the performance of the resultant catalysts. The as-prepared Ф-P-Ru catalysts are shown to be promising mercury-free candidates for the synthesis of vinyl chloride monomer.

Regulation of the Ru/Cl ratio could increase the amount of ruthenium oxides, improve the dispersion of Ru species on the carrier and enhance the adsorption ability of the reactants, consequently improving the catalytic performance.

The Ru-based catalysts, including Ru/AC (activated carbon), TPAP (tetrapropylammonium perruthenate)/AC, TPAP/AC-HNO3, and TPAP/AC-HCl, were prepared and assessed for the direct synthesis of vinyl chloride monomer. The results indicate that the TPAP/AC-HCl catalyst exhibits the best performance with the conversion falling from 97% to 91% in 48 hours’ reaction under the conditions of 180 °C, a GHSV(C2H2) of 180 h−1, and the feed ratio VHCl/VC2H2 of 1.15. The substitution of RuCl3 precursor with high valent TPAP species leads to more ruthenium oxides active species in the catalysts; the acidification treatment of carrier in TPAP/AC catalyst can produce an enhanced interaction between the active species and the modified functional groups on the carrier, and it is beneficial to inhibit the carbon deposition and sintering of ruthenium species in the reaction process, greatly increase the adsorption ability of reactants, and further increase the amount of dominating active species in the catalysts, thus improving the catalytic performance. This also provides a promising strategy to explore high efficient and economic mercury-free catalysts for the hydrochlorination of acetylene.

Oxidation modification enhances the interaction between the oxygenated functional groups and Ru species, strengthens the adsorption of reactants, and augments the amount of active species, enhancing the catalytic performance of the catalysts.

Recently, many scientists have focused on the development of green industrial technology. However, the process of synthesizing vinyl chloride faces the problem of Hg pollution. Via a novel approach, we used two elements Mo and Ti to prepare an inexpensive and green binary transition metal nitride (BTMN) as the active ingredient in a catalyst with nano-sized particles and an excellent degree of activation, which was supported on activated carbon. When the Mo/Ti mole ratio was 3:1, the conversion of acetylene reached 89% and the selectivity exceeded 98.5%. The doping of Ti in Mo-based catalysts reduced the capacity of adsorption for acetylene and also increased the adsorption of hydrogen chloride. Most importantly, the performance of the BTMN excelled those of the individual transition metal nitrides, due to the synergistic activity between Mo and Ti. This will expand the new epoch of the employment of transition metal nitrides as catalysts in the hydrochlorination of acetylene reaction.

The development of green catalysts for the calcium carbide acetylene method synthesis of vinyl chloride monomer (VCM), is essential material to industrial polyvinyl chloride production. The original catalyst HgCl2 easy to volatile during the reaction lead to environmental pollution. Here we present three different transition metal nitride load into activated carbon (AC): VN/AC, Mo2N/AC, and W2N/AC as novel catalysts. W2N/AC and Mo2N/AC was a relatively stable catalyst to compared with VN/AC. All of them VCM selectivity can maintain 98%. More HCl ratio for Mo2N/AC lead its acetylene conversion reach 80%. The former two catalysts are promising candidates for acetylene hydrochlorination.

Because of the toxicity of mercury catalysts, a nonmercury heterogeneous catalyst for acetylene hydrochlorination has been widely investigated. In this Perspective, we introduce the development of Au-based catalysts, Ru-based catalysts, other metal catalysts, and a carbon nitride catalyst. The effect of the promoter and the carbon support property on the catalytic performance of the AuCl3 catalyst is discussed in detail, and the potential application of other catalysts is also reviewed on the basis of experimental and theoretical studies. At present, it is predicted that a Au-based catalyst may be the optimal candidate catalyst for industrial application in the production of polyvinyl chloride from calcium carbide, but other catalysts should still be further investigated to improve their catalytic performance and their cost advantages.