Investigation Of A Novel Mixed Dialkyl Oxalates Fuel And Construction Of Safety Fuel System

Using coal and renewable biomass resources as raw materials,non-petroleum-based oxygenated fuels which are performance stable,high safty,clean and easy to industrialize were developed to partially or completely replace petroleum-based fuels such as gasoline and diesel.It is an important way to ensure China's energy security and social sustainable development.Although the production cost of methanol synthesized from syngas is low,it has inherent defects such as volatile,high vaporization heat,corrosive metal,easy to absorb water and poor solubility with diesel oil.Ethanol and other low carbon mixed alcohols fuels need to overcome the high production cost and shortage of production capacity.The synthesis of methanol from syngas also has the problems of excessive carbon monoxide and insufficient hydrogen,which require water-gas shift reaction.The synthesis of ethanol and low carbon mixed alcohols also need water-gas shift reaction,and the production cost is high,the capacity is insufficient.In order to overcome the shortcomings of the above fuel systems,give full play to the advantages of existing production platforms and raw materials,and reduce China's dependence on petroleum-based fuels,this paper proposes to use mixed dialkyl oxalates as alternative fuel and off-line energy carrier based on rational molecular design.Mixed methyl ethyl oxalate(mMEO)is a colorless transparent liquid at room temperature,and contains a certain proportion of dimethyl oxalate(DMO),methyl ethyl oxalate(MEO)and diethyl oxalate(DEO).It can be used as alternative fuel or fuel additive.It is a clean,safe and cost-effective alternative fuel with great development potential.The Dialkyl oxalate can be synthesized under mild conditions by carbon monoxide(CO)coupling with alcohols such as methanol and ethanol.The CO/H2 ratio of syngas is more suitable for the synthesis of oxalate,which can save the energy and material consumption of water gas conversion and carbon dioxide separation.CO can be obtained from various industrial tail gases rich in CO,such as blast furnace gas,converter gas,yellow phosphorus tail gas,calcium carbide gas,or from reduction of CO2.Hydrogen can be produced from solar,wind and geothermal energy.Synthesis of dialkyl oxalate from syngas can consume CO in syngas and make H2 ratio increases.The same volume of CO and H2 have similar heating values,but CO is difficult to liquefy and is a highly toxic gas.By synthesizing dialkyl oxalate,chemical liquefaction of CO can be achieved by means of methanol and ethanol,and the chemical energy of CO can be converted into a part of liquid dialkyl oxalate.Through chemical transformation,CO and H2 can be transformed into safe energy carriers,which can save operating costs and realize safe and convenient storage and transportation.The main research contents and conclusions of this study are as follows:(1)This paper proposes a basic standard for fuel selection,and comprehensively analyzes the physical and chemical properties,comparative advantages,safety and economy,energy storage efficiency,physical and chemical properties and production costs of oxalates such as DMO,MEO and DEO.The energy storage efficiency of fuel is analyzed by lower heating value and available energy.The physical and chemical properties of various synthetic products were compared.The physical and chemical properties of oxalate,such as DMO,MEO and DEO,and the feasibility of mMEO as alternative fuel were investigated.It was found that of dimethyl oxalate has a higher second law energy storage efficiency than tris-methoxy dimethyl ether and dimethyl carbonate.mMEO has the advantages of low-cost production,high flash point,safe use,low latent heat of vaporization and better miscibility with gasoline and diesel.It has short carbon chains and high oxygen content,which can effectively reduce the formation of soot.(2)The solubility of oxalate mMEO in gasoline,diesel and various hydrocarbon model fuels was studied systematically.It was found that mMEO formed when half methyl groups were replaced by ethyl groups in DMO could be mutually soluble with gasoline at-10? and diesel at 85?.The mixed methyl oxalate(mMBO)has good solubility with diesel at room temperature.A series of mixed oxalic acid esters were synthesized from DMO which is an intermediate of ethylene glycol from syngas.The pilot scale production of mMEO was carried out in the reaction kettle of 3000 L,and about 5 t of qualified products were obtained.A lot of application experiments were carried out.(3)Through the molecular dynamics simulation,the aggregation phenomenon of oxalate in weak polar hydrocarbon solvent was investigated.The mean square displacement,self-diffusion coefficient and radial distribution function of the mixed fuel system were studied.The density and solubility parameters of different dialkyl oxalates were predicted and analyzed.The tendency of MEO to form aggregates in n-hexane and two isohexanes is greater than in 1-hexene,and toluene.Some of the dialkyl oxalate molecules in the solution are in a free state,and some dialkyl oxalate molecules form unstable dimers,as well as trimers.Both n-butanol and toluene have a function of promoting dissolution of MEO in n-hexane.But the mechanism of increasing dissolution is different.According to the RDF analysis,n-butanol can be coordinated to the carbonyl oxygen atom of MEO by hydrogen bonding.However,the? interaction between toluene and MEO is stronger,and toluene tends to bind to MEO in n-hexane solution,which reduces the tendency of MEO to self-aggregation.(4)In the experimental part of the engine bench test,the engine performance of different contents of mMEO/gasoline blended fuel and the engine performance of oxalic acid mixed alcohol ester(mMAO)/diesel blended fuel under different working conditions were tested.The study found that the addition of mMEO to gasoline can improve thermal efficiency,reduce CO emissions overall,and reduce particulate PM2.5 emissions under certain conditions.The equivalent fuel consumption rate and thermal efficiency of 20%mMAO/diesel composite fuel are close to that of diesel.mMAO can reduce particulate PM2.5 emissions from diesel engines.At the same time,the copper corrosion test of mMEO,the swelling test of mMEO and gasoline blended fuel for different rubbers were studied.The performance of mMEO on steam generators were studied fo replacement of boiler fuels.