The Study Of RuCl₃ Catalyst Systems For Synthesizing Methyl Propionate By Hydro-esterification Of Ethylene

Methyl propionate is an important organic synthesis intermediate.Methyl methacrylate is its downstream product with wide application.And it is an important monomer for the synthesis of polymethyl methacrylate.The world production capacity of methyl methacrylate has been 3.89 million tons in 2017.The demand of global methyl methacrylate will increase by a rate of 2–3% per year by 2020.At present,China is the world's largest consumer of methyl methacrylate,with an external dependence of more than 60% and an annual demand growth rate of more than 10%.It is one of the top ten products with the highest dependence on organic chemical imports.The main production processes of methyl methacrylate include the acetone cyanohydrin method(ACH method),the isobutylene direct oxidation method,the ethylene carbonylation method(BASF method),and the Alpha method(Lucite's modified ethylene carbonylation method).Among them,the Alpha method produces methyl methacrylate with no special material equipment,low maintenance cost,high atomic utilization and environmental friendliness.However,the catalyst stability and conversion need to be improved,and the carbon monoxide as the raw material exists large safety hazard.At the same time,since methanol(raw material)and methyl propionate(intermediate product)form an azeotrope,and methyl methacrylate is used as a high-end material is in high purity,which needs complex separation equipment leading to increase the production cost of this route.We have chosen carbonylated methyl formate instead of toxic carbon monoxide as the reaction raw material,eliminating the carbonylation process with methanol,and the reaction process is simpler,which is beneficial to the development of high-performance catalyst.Ru Cl3 is used to catalyze the hydro-esterification of ethylene and methyl formate to produce methyl propionate avoiding using toxic,unstable,and expensive ruthenium compounds.Promoters and solvents are high boiling compounds,making product separation easier.In this paper,we developed Ru Cl3-[PPN]Cl-Et4NI(Bis(triphenylphosphine)iminium chloride([PPN]Cl),Tetraethylammonium iodide(Et4NI))catalyst system,in which the conversion of methyl formate is 93.9%,and the selectivity of methyl propionate is 90.9%,in N,N-dimethylformamide solution,at 165 ° C and under 2.5 MPa.It is noteworthy that we furth developed simpler inorganic Ru Cl3-Na I catalyst system obtained 88.8% conversion of methyl formate and 97.6% selectivity to methyl propionate.The first chapter of this thesis is introduction,introducing the physical and chemical properties,application,demand and synthesis methods of methyl methacrylate;the basic properties,application and synthesis methods of methyl propionate;research background of the hydro-esterification of ethylene method;the basis and significance of this thesis.The second chapter of this thesis is experimental part,which introduces experimental drugs,reagents and gas,experimental instruments,experimental operation and drawing working curve,and characterization analysis instruments(Nuclear Magnetic Resonance Spectrometer,Infrared Spectrometer,X-ray Photoelectron Spectrometer,X-ray Powder Diffractometer,Small Molecule Single Crystal Diffractometer).The third chapter of this thesis is studying Ru Cl3-[PPN]Cl-Et4 NI catalyst system.The optimal reaction temperature and time are 165 °C and 5 h,respectively.Exploring roles of the components of the catalyst system,Ru Cl3 is the main catalyst of the catalyst system.The promoters([PPN]Cl and Et4NI)have no catalytic effect on the reaction without Ru Cl3.Using Ru Cl3,the promoters can inhibit the decomposition of methyl formate,reducing the production of methanol and carbon monoxide,and increasing the conversion of methyl formate and the selectivity to methyl propionate.Through the analysis of IR and XPS,it is found that N,N-dimethylformamide is coordinated with Ru Cl3.The fourth chapter of this thesis is studying Ru Cl3-Na I catalyst system.The Et4 NI as promoter has a more obvious effect on the reaction than [PPN]Cl.The addition of optimal amount Et4 NI can inhibit the decomposition of methyl formate.Further increasing the amount of promoter,it accelerates the decomposition of N,N-dimethylformamide to produce carbon monoxide and dimethylamine,poisoning the catalyst by carbon monoxide.Even if the promoter Et4 NI is converted to Me4 NI during the reaction,it has almost no effect on the yield of reaction.It is speculated that the iodide ion may be a key component of promoter.Ru Cl3-Na I catalyst system was further found.The methyl propionate was separated and purified by reduced pressure distillation of the liquid product.The product was verified to be methyl propionate by nuclear magnetic data.The fifth chapter of this thesis is conclusion and scope.