Engineering Study On Mercury-free Catalyst For Chloroethylene

Polyvinyl chloride(PVC),as one of the world’s five general plastics,plays an important role in film,sheet,packaging materials,medical treatment and daily necessities.Vinyl chloride(VCM)is an important monomer in the synthesis of polyvinyl chloride.There are three main methods to synthesize VCM in industry,namely ethane method,ethylene method and acetylene method.However,under the energy situation of rich coal and little oil in China,acetylene method based on coal chemical industry has become the main production mode of VCM in China.At present,the acetylene method in industry mainly uses mercury chloride as the catalyst of the active component,but mercury is a metal element that has serious harm to the environment and human health.And with the signing of the convention on mercury prevention and control in Minamata,the acetylene method urgently needs to use a new type of green catalyst for industrial production.Now,researchers have done a lot of research on new green catalysts.In this paper,the new type of green catalyst designed for the study of dynamics and the appropriate reactor simulation design and optimization,and acetylene production of vinyl chloride synthesis and conversion process equipment design.The main research content of this paper is divided into the following three parts:(1)The intrinsic kinetics of a gold based catalyst with high activity and long service life was studied in a laboratory-made fixed bed reactor.Under the condition of reasonably assuming the reaction mechanism of catalyst,the reaction kinetic equation of acetylene hydrochlorination was deduced by using Langmuir adsorption isotherm equation,and the activation energy required for the reaction was calculated as.This equation is close to the experimental value,which proves the rationality of the hypothesis and the accuracy of the equation.Based on the obtained kinetic equation,a one-dimensional quasi-homogeneous model was used to simulate the temperature and concentration distribution in the laboratory reactor.(2)Through the calculation of the thermodynamics of acetylene hydrochlorination reaction,the feasibility of the reaction is determined,and the maximum reaction temperature that the reaction can withstand is determined by the highest conversion rate and selectivity that can be achieved through the reaction equilibrium.By using Aspen Plus simulation software,the catalyst was analyzed in a constant temperature reactor to determine the appropriate operating conditions.The simulation analysis and optimization of acetylene hydrochlorination in adiabatic reactor and one-stage heat exchange reactor were carried out respectively.It was found that the adiabatic reactor and one-stage heat exchange reactor could not meet the requirements of industrial production.In view of this situation,two-stage heat exchange reactor can effectively solve the problem of low acetylene export conversion rate,so that the final acetylene export conversion rate reached more than 99%.(3)For the designed reactor,the technological process of the synthesis of vinyl chloride by acetylene with calcium carbide of 50,000 tons per year was designed and calculated,and the material and energy balance of the entire technological process were calculated.Under the premise of energy saving and environmental protection,the entire process was optimized.By optimizing the designed process,the saturated steam used for preheating is replaced by the reaction product,which can save the production cost of preheater and the amount of industrial saturated steam,and has remarkable economic and social benefits.Through the calculation of the main equipment in the process of vinyl chloride production,the data reference for industrial equipment manufacturing is provided.