Study On The Microreactor Process For Extraction Of Rhodium From Waste ROPAC By Hydrogen Peroxide Oxidatio

Rhodium（Rh）,with its high value,scarce reserves,and irreplaceable catalytic performance,has always played a crucial role in environmental protection and chemical production in human society.As one of the core catalysts for low-pressure carbonyl synthesis of butanol and octanol,triphenylphosphine acetylacetone carbonyl rhodium（ROPAC）has a high rhodium content,large production scale,and significant annual waste volume,making it an important source of raw materials for rhodium recycling industry.However,traditional rhodium recovery processes such as pyrometallurgy and hydrometallurgy suffer from complex process flows,high energy consumption,and unfavorable production environments.Additionally,the oxidative extraction method is prone to safety hazards such as explosions,which makes it difficult to align with the national strategic direction of"energy conservation,emission reduction,safety,environmental friendliness,and green production"in the metallurgical,chemical,and material industries.Therefore,the development of a new rhodium catalyst recovery process to replace and upgrade the traditional methods has become a current research focus in the industry.This study introduces the technology of 3D printed microchannel reactors into the process of recycling rhodium from waste ROPAC catalysts.The technical route involves direct oxidation and extraction of rhodium using hydrogen peroxide,with the entire reaction confined within the microchannels.This enables low liquid hold-up continuous flow production,thereby enhancing production safety.Three different types of microchannel reactor devices were employed,and a two-stage oxidation-extraction process achieved a rhodium recovery rate of over 95%.Furthermore,addressing the challenges of complex composition in waste ROPAC catalysts and the difficulty of chemical analysis and mechanism analysis,a novel approach combining first-principles calculations with deep learning-driven molecular dynamics simulations was utilized.This enabled the simulation and calculation of two chemical reaction processes:Cl-induced deactivation and hydrogen peroxide oxidation-extraction in ROPAC catalysts.The main research contents and conclusions are as follows:（1）The structure analysis,differential charge analysis and HOMO-LOMO orbital analysis were carried out by AIMD simulation.It was found that the presence of Cl element had a strong influence on Rh in the structure of ROPAC catalyst,resulting in the change of molecular structure and charge distribution of the catalyst,which affected the activity of Rh and led to the deactivation of the catalyst.H₂O₂ has a strong oxidation and structural destruction effect on the structure of ROPAC waste catalyst,including Rh atoms,PPh₃ and acac molecular groups.Through the LAMMPS kinetic simulation of Deep MD deep learning training,the chemical reaction process of H₂O₂ oxidative extraction of Rh in ROPAC waste catalyst is visually reflected,which provides a mechanistic support for the oxidative extraction process,and reveals several possible forms of Cl element in the oxidative extraction process,including HCl,Cl₂,HCl O,etc.（2）The effects of reaction temperature,phase ratio,reaction time and pressure on the extraction of rhodium from ROPAC by hydrogen peroxide oxidation extraction were investigated by a single-channel six-module series microreactor.The results show that the extraction rate,distribution ratio and extraction factor of rhodium increase first and then decrease with the increase of reaction temperature,increase with the increase of phase ratio,and increase first and then decrease with the increase of two-phase contact time.When the temperature is 120°C,the phase ratio is 1:1,the total flow rate of oil-water two-phase is 40 m L/min,and the pressure is 2.5 Mpa,the extraction rate of rhodium is up to 91.07%.（3）A microchannel tubular dynamic reactor made of Hastelloy corrosion-resistant alloy was used to study the effects of phase ratio,time and rotational speed on the oxidation extraction rate.The results showed that the rhodium extraction rate reached83.47%when the temperature was 105.8°C,the oil-water flow ratio was 30:50 m L/min,and the equipment speed was 1200 rpm.The results of continuous 24 h test showed that the extraction rate of rhodium in the first treatment reached 75.2%,and the extraction rate of rhodium in the second treatment reached 91.33%.The treatment capacity of waste ROPAC in the secondary treatment can reach 70 m L/min at 110°C.（4）A stainless steel column static microreactor was successfully assembled.Based on this,a new process of rhodium recovery by oxidation extraction was studied.Response surface methodology was used to optimize the process parameters such as temperature,time and phase ratio,and the influence of three factors on the recovery rate of rhodium was systematically investigated.The results showed that under the conditions of reaction temperature 110°C,phase ratio 1:1,reaction time 29 min and two-phase total flow rate 140 m L/min,the rhodium oxidation extraction rate was 75.98%,and the relative error with the predicted value of 76.06%of the response surface was 0.8%（<5%）.The organic phase collected after the first stage of treatment was subjected to secondary treatment for 4 h under the same process conditions.The results showed that the two-stage comprehensive oxidation extraction rate of Rh reached 95.6%.In this paper,the recovery of precious metal waste catalyst is taken as the research topic,and the 3D printing microchannel reactor technology with independent intellectual property rights of the team is taken as the fulcrum.A set of large flow microchannel reactor equipment with continuous flow,controllable temperature and high temperature and high pressure resistance is designed and developed.It has a good application prospect in the production of rhodium in the recovery of waste ROPAC catalyst by hydrogen peroxide oxidation extraction.It solves the problems of volatilization of organic matter,flash explosion,long reaction time and high energy consumption in the traditional kettle reaction process,and achieves good application in the same type of chemical reaction.