| Reactive distillation(RD)is a process intensification technology that couples chemical reaction and distillation separation.It integrates reaction equipment and separation equipment into a single RD column,which has outstanding advantages such as saving investment cost and energy consumption.The catalytic packing,as one of the important internal components in a heterogeneous RD column,the chemical reaction and phase equilibrium separation are carried out simultaneously inside of the catalytic packing in the column,and their interactions are influenced by many factors.The reaction-separation performances of catalytic packing are analyzed theoretically at the first in this work.The difference in fluid flow between the catalytic module and the separation module in the conventional catalytic packing is the main factor to result in the mass transfer resistance around the catalyst surface in the catalytic module,and the supported catalytic packing can be used to attenuate or eliminate this adverse effect in the experimental process.In addition,the dimensionless number Da is defined as the ratio of reaction rate and inter-phase mass transfer rate,which is used to characterize the coupling degree between reaction and separation of catalytic packing in the specified operating conditions and evaluate the synergistic effect of reactionseparation.A porous adhesive layer was coated on the surface of the stainless metal packing with epoxy resin as the main adhesive composition,and the catalytic active component polystyrene sulfonic acid(PSS)was combined with the porous structure layer through a coupling agent.Then an acidic supported catalytic packing can be prepared after optimization of the coating thickness and ion exchange capacity(IEC).The supported catalytic packing prepared in this way was utilized to carry out experimental studies of the RD process.Experimental and simulation studies were conducted on the RD process of ethanol esterification with acetic acid that was regarded as a fast-rate reaction.The kinetic model equations of the corresponding catalysts were obtained through kinetic experiments,and the external diffusion resistance was verified as the main factor affacting the catalytic efficiency of the random catalytic packing(RCP).The actual performance of the RCP and the random supported packing(RSP)were compared by the lab-scale RD column experiments.The process simulation software Aspen Plus combined with suitable model parameters was used to simulate the process and investigate the reaction-separation synergy of the two catalytic packings,respectively.It is concluded that the RSP is more suitable for ethyl acetate production using the RD process than the RCP.Experimental and simulation studies were conducted on the RD process of nbutanol esterification with acrylic acid that was regarded as a relatively slow-rate reaction as ethyl acetate process.The kinetic models and their parameters that include side-reaction,dimerization of acrylic acid and etherification of n-butanol,were obtained through kinetic experiments.The lab-scale RD apparatus was equipped with a vacuum system to carry out vacuum RD experiments for comparison RCP and RSP.Then,the lab-scale and the plant-scale RD processes were simulated,respectively,to investigate the reaction-separation synergy among catalytic packings,it was concluded that the structured catalytic packing(SCP)or RCP is more suitable for this butyl acrylate RD process.However,the structured supported packing(SSP)can change the selectivity of the reaction products to some extent. |
