Kinetics Of Ethyl Benzene Dehydrogenation Over Catalysts With Low Steam-to-oil Ratio Under Negative Pressure And Process Analysis

Kinetics of ethyl benzene dehydrogenation over commercial catalysts with low STO (steam-to-oil) under Negative Pressure were studied based on energy-saving process, which were developed for reactor simulation and process analysis.In an isothermal integral reactor, effects of temperature, pressure, LHSV, STO, feed mole ratio of styrene to ethyl benzene and hydrogenation to ethyl benzene on reaction abilities over two kinds of catalysts were investigated under the experimental arrange around the industrial operation conditions. The experimental results showed higher temperature, lower pressure, lower STO and higher LHSV increased the conversion of ethyl benzene, lower temperature, lower pressure, higher STO and higher LHSV increased the selectivity of styrene. The addition of styrene and H2in feed restrained ethyl benzene dehydrogenation reaction.Kinetic models for two kinds of catalysts on the LHHW formalism were established. Kinetic parameters were obtained by Levenberg-Marquardt method. The kinetic models were proved to be reliable by the statistical tests, residual analyses and simulation results for80kt/a industrial radial reactors. Based on the operation record data for80kt/a styrene plant, deactivation kinetics of a commercial catalyst for ethyl benzene dehydrogenation was derived.Based on500kt/a styrene plants using3kinds of process technology for ethyl benzene dehydrogenation, effects of equilibrium, operation pressure and catalyst bed volume ratio (V2/V1) of two-stage reactors under low STO were discussed. Equilibrium limit caused by low STO can be reduced by high temperature and lower outlet pressure for2nd reactor. Effect of pressure for reaction ability was investigated based on reaction rate, which showed the existence of optimal operation pressure proved by experiments on isothermal reactor. Optimal pressure profile line for two-stage adiabatic radial reactors was presented. Optimal operation outlet pressure for two-stage adiabatic radial reactors was predicted. Effect of catalyst bed volume ratio (V2/V1) of2nd reactor to1st reactor among0.5to2.0on reaction results was also studied, which shows the existence of optimal V2/V1. When reactors were designed in optimal V2/V1, optimal conversion of ethyl benzene to styrene and yield of styrene were achieved. The appropriate design value arrange of V2/V1was proposed.