Preparation And Performance Of SnL_x@g-C₃N₄/AC Catalyst For Acetylene Hydrochlorination Reaction

Polyvinyl chloride?PVC?is the world's third largest general purpose plastic,after the production of polyethylene?PE?and polypropylene?PP?.PVC has many advantages.For example,cheap,good acid and alkaline resistance,effective oxidation resistance,high mechanical parameters and not flammable.The products have been widely used in construction,chemical,electrical and other industries.Since the reforming and opening up,China's economy has rapidly developed.There are consuming more and more.PVC products in construction and medical areas.Three methods?ethane method,ethylene method,and acetylene method?are used in PVC monomer vinyl chloride production.These three production methods are derived from different basic raw materials.Ethane method is the leading method in three methods.It is prepare vinyl chloride from ethane produced.Vinyl chloride method is mainly used to prepare vinyl chloride based on petrochemical in countries with abundant petroleum resource.China's coal deposits are very large,Acetylene preparation of vinyl chloride is widely used in China because China has rich coal.Sn-based catalyst has good catalytic activity for acetylene hydrochlorination.Sn base catalyst is also used in acetylene hydrochlorination because of cheap and green mercuric.However,tin ions are easy to volatilize and lose and Sn²⁺is easy to oxidize into Sn⁴⁺.In this paper,a series of Sn-based catalysts were prepared by equal volume impregnation method.Firstly,Carbon nitride catalyst was prepared from activated carbon with urea as precursor.A series of SnCl₂@g-C₃N₄/AC catalysts with different loading and coupling SnCl₂ and g-C₃N₄/AC catalysts were prepared by impregnation method.Tin based catalysts were prepared for the hydrochlorination of acetylene.A series of SnCl₂@g-C₃N₄/AC catalysts with obvious difference in reaction effect were obtained by using different organic solvents to dissolve and impregnation the active components.Then,other metals with different loads were added as auxiliary agents on the basis of Sn base catalyst.The addition of the auxiliary metal changed the existence state of tin through electron transfer between tin atoms.The synergistic effect was conducive to improving the dispersity of Sn and increasing the service life of the catalyst.Finally,the active component Sn was effectively fixed by the introduction of the organic ligand acetylacetone.This method not only increased the service life of the catalyst,but also enhanced its catalytic activity.The performance of the catalyst for acetylene hydrochlorination was evaluated with a fixed bed reactor.X-ray photoelectron spectroscopy?XPS?,nitrogen physical adsorption desorption?BET?,X-ray diffraction?XRD?,synchronous thermogravimetric analysis?TG?and other characterization methods were used to systematically explore the physical and chemical properties of the catalysts.The mechanism of catalyst action and deactivation mechanism were discussed.The conversion rate of g-C₃N₄/AC acetylene prepared from coconut shell activated carbon treated with nitric acid was 94%,and the coupling catalyst of SnCl₂ and g-C₃N₄/AC was evaluated.The conversion rate of 10%SnCl₂@g-C₃N₄/AC catalyst was higher,reaching 76%.The results show that the catalyst with the best performance of 5%Bi-10%Cu-10%Sn/AC was screened out,and the conversion rate was up to 98%.The selectivity was almost 100%,and there was not deactivation of the catalyst within 100 h.The addition of the helper metal change the existence state of tin,and can improve the dispersion of Sn by electron transfer between the Sn atom.Sn?acac?₂Cl₂/AC catalyst with organic ligand was prepared.And the conversion rate reached 96%,and the selectivity was also close to 100%after 500 min in performance test.The catalyst deactivation was caused by the further loss of tin chloride,which is generated by the reaction of tin acetylacetone and hydrogen chloride.