Study On The Relationship Between The Surface Groups Of Activated Carbon, The Active Phase And The Performance Of Gold Catalyst In Acetylene Hydrochlorination

Polyvinyl chloride,composing of vinyl chloride monomer,is widely used in all of the life and production.The preparation methods mainly include acetylene hydrochlorination and ethylene oxychlorination.In China,determining by the special energy structure of crude petroleum,gas and richer coal resources,mostly use the former approach.The toxicity mercuric chloride supported on activated carbon is acted as catalyst in Industrial.Due to easily volatility of mercury chloride,causing serious harm to humans and the environment.Hence,it is exactly needed to design a green,efficient and economic catalyst to replace mercuric chloride.The higher activity of gold catalyst has attracted many researchers,and is expected to replace the mercuric chloride catalyst in the future.However,gold catalyst is more easier to be deactivated,and the stability is very poor.At present,activated carbon is frequently used as the carrier in industrial,unfortunately,there is a fatal drawback,that is low mechanical strength and more easier pulverization.Therefore,it is urgent necessary to explore high mechanical strength,good thermal conductivity carrier to replace activated carbon.But considering that the Au³⁺ species need to rely on the activated carbon surface oxygen containing groups to stabilize.Thus,the gold base active phase,urgently to investigate,is used to stabilize Au³⁺ instead of dependment on the oxygen containing groups on the surface of activated carbon.Mainly results of this paper are as follows:Modulation of activated carbon?AC?,first pickling,then calcination at different temperatures,is the carbon materials of different kinds and quantity of oxygen containing groups,for example,the AC-n-N900 was prepared that AC was treated with nitric acid,and then calcinated at 900 ? under N₂ atmosphere two hours.We construct CsAuCl₄ active phase,and prepare Au-Cs catalyst by impregnation,with modulation activated carbon as carrier,wherein the gold loading is 1 wt% and the gold cesium mass ratio is 1:4.The catalytic performance of Au1-Cs4/AC-n-N900 catalyst with the CsAuCl₄ active phase was surveyed.Found that it has high initial activity and stability,the main reason for the improvement of activity is that CsAuCl₄ has good reducing resistance and thermal stability,in other words,it can improves Au³⁺ stability and increase the amout of gold species in oxidation state,and don't rely on oxygen containing groups on the surface of the activated carbon.The novel active phase Cs_aAu_bCu_cCl_d?d=a+3b+2c?is designed on account of the CsAuCl₄ active phase plus the third metal element Cu.The catalyst of AuCsCu/AC-nN900 is prepared by Cs_aAu_bCu_cCl_d active phase and Au loading is 0.2 wt%.It is showed the super-performance that the more higher initial acetylene conversion equally with AuCsCu/AC-n and superior stability,under the reaction conditions of P=0.1 MPa,T=180 ?,GHSV=740 h-1 and n?HCl?/n?C₂H₂?=1.2.The characterization results of XRD,H2-TPR,C₂H₂-TPD and TG shows that the main reasons for the improvement of catalyst activity and stability of AuCsCu/AC-n-N900 are further improving the dispersion of gold nanoparticles,Au³⁺ contents and carbon deposition resistance.Therefore,Au³⁺ can be better stabled by novel active phase Cs_a Au_bCu_cCl_d.In summary,it is revealed the fact that such excellent catalytic activity and stability at Au more lower loading quantity,indicating that it has good prospects for industrial applications.