| As an essential green chemical,hydrogen peroxide has a wide range of applications.The anthraquinone process is one of the most popular industry-methods for the production of hydrogen peroxide and the anthraquinone hydrogenation and anthrahydroquinone oxidation are the core sections.However,due to the poor solubility of hydrogen and oxygen,the macroscopic reaction rates of hydrogenation and oxidation are limited by the gas-liquid mass transfer rate,which greatly affects the production efficiency to increase the running cost.Considering the advantages of process intensification of the gas-liquid mass transfer in a rotating packed bed(RPB)reactor,this work applied the RPB reactor to the anthraquinone(EAQ)hydrogenation and anthrahydroquinone(EAQH2s)oxidation,aiming to intensify the two processes to accelerate the macroscopic reaction rate.The intensification mechanism of the RPB reactor was further discussed.The main conclusions are as follows.(1)In EAQ hydrogenation reaction,the quasi-homogeneous catalytic hydrogenation method was used to investigate the effects of RPB speed,initial concentration of working solution,hydrogen pressure,reaction temperature,and solvent volume ratio on H2O2 yield(B)and active anthraquinone selectivity(S).The increase in the rotational speed of the RPB reactor,the hydrogen pressure,and the reaction temperature were conducive to the acceleration of the hydrogenation rate.However,increasing the hydrogen pressure and reaction temperature was unfavorable for selectivity,which was disadvantageous for the recycling of the working solution.Within the range of experimental conditions,the maximum H2O2 yield(B=13.08 g/L)can be obtained when the initial concentration of the working solution(CEAQ)matched the solvent volume ratio(VTMB:VTOP)best,where CEAQ=100 g/L,YTMB:YTOP-3:3.Compared with the stirred tank reactor(STR),under the same reaction conditions,the space time yield of anthraquinone hydrogenation in the RPB reactor was 369.8 gH2O2 g-1Pd h-1,which was 25 times that of STR(14.5 gH2O2 g-1 Pd h-1).The RPB reactor intensifies the gas-liquid mass transfer between anthraquinone working solution and hydrogen,which can effectively improve the macroscopic reaction rate of hydrogenation..(2)In EAQH2s oxidation reaction,a tandem reactor combining a rotating packed bed(RPB)reactor with a stirred tank reactor(STR)was proposed.Firstly,the factors that affected the stability of hydrogen peroxide were excluded:using the packing with the glass fiber as base and polytetrafluoroethylene(PTFE)as coating,and adding phosphoric acid aqueous solution as a stabilizer,can effectively improve the stability of the hydrogen peroxide generated during the oxidation process.At the same time,it can realize the in-situ extraction of hydrogen peroxide.In the tandem reactor,the oxidation and extraction rate increased first and then stabilized as the RPB speed increased,and decreased as the oil-water(VO:VW)volume ratio increased.Meanwhile,increasing the liquid flow rate,gasflow rate,reaction temperature and using oxygen as the gas phase is beneficial to accelerate the oxidation and extraction rate.Further,the mechanism of the RPB+STR tandem reactor for enhancing the EAQH2s oxidation and hydrogen peroxide extraction process was discussed preliminarily.The tandem reactor can achieve a higher EAQH2s conversion and hydrogen peroxide extraction amount in the same reaction time.The reason was that the introduction of STR in the tandem reactor inhibited the aggregation of oil droplets dispersed in the water phase and the layering of the two phases between oil and water,leading to the increase in the number of dispersed oil droplets per unit volume of the water phase.In the experimental operating range,within 5 minutes,the EAQH2s conversion and hydrogen peroxide extraction efficiency can reach 21-45%and 72-83%respectively in the RPB+STR tandem reactor.Compared with other reactors,the RPB reactor has obvious advantages in oxidation and extraction rates,and has the potential for industrial application. |
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