Catalytic Decomposition Of Methyl Formate And Methyl Tert-Butyl Ether In Ship Exhaust Gas

Recently,with the public environmental awareness increasing,the problem of pollution has become an indispensable part of the ship operation.It is remarkable that concern is primarily about emissions in the form of VOC due to its character of volatilization,high toxicity and difficult treatment.Lowering VOC has become a catchword in the reduction of ship exhaust emission.With respect to Esters,it is relatively easy to pyrolyze because of two oxygen atoms in their structure.Furthermore,as the simplest kind of Esters,methyl formate has strong volatility,and it is also the main product of the combustion reaction of hydrocarbon fuel in NOx environment,respectively.On the other hand,as a representative of ethers which are are highly hazardous,difficult decomposition and highly viscous,methyl tert-butyl ether are widely existed in ship exhaust emissions,which mean that methyl tert-butyl ether has certain research value.In summary,the elimination of both methyl formate and methyl tert-butyl ether is of importance for the reduction of VOC.This paper mainly studies the feasibility of low temperature catalytic decomposition of ship exhaust VOC.Since the ship's exhaust gas outlet has low pressure and low oxygen characteristics,the model of catalytic pyrolysis can be used to simulate the pyrolysis of the actual ship's exhaust gas outlet.The quartz tube was used as the reaction tube to simulate the reaction conditions at the outlet of the ship's exhaust emission.The VOC vapor were transported into the reaction tube by bubbler,and the change of the products during catalytic pyrolysis were studied through gas chromatography.The catalysts used in this research were various metal oxides such as aluminum,copper,magnesium,manganese,and some rare earth oxides.According to the experimental of pyrolysis,for methyl formate,it is pyrolyzed in the range of 800 K-1000K without catalyst,which can not feed the requirements of actual ship's exhaust gas outlet.For the catalytic pyrolysis experienment,?-Al2O3 has the best catalytic pyrolysis effect,which enables the methyl formate to be pyrolyzed in the range of 500 K-700 K.Rare earth oxide and CuO catalysts have different degrees of deactivation.This paper also make a research on the product of methyl formate in pyrolysis experienment.The experienment found a new product of methyl formate,and it prove to be dimethyl ether.The results show that most of the dimethyl ether is derived from the reaction of methyl formate,and a small part is derived from the reaction between methanol.As for methyl tert-butyl ether,a representative of the ethers in the ship's exhaust VOC,it is pyrolysis in the range of 800 K-1200 K,which can not fulfil the demands of actual ship's exhaust gas outlet.Among the amount of catalysts,the ?-Al2O3 catalyst has achieved best catalytic effect and can raise the catalytic pyrolysis range of methyl tert-butyl ether to 400 K-600 K.The main decomposition products of methyl tert-butyl ether are methanol and isobutylene,and the content of both increases first and then decreases.This paper added to simulate the low-oxygen lean-burning environment based on the catalytic pyrolysis experiment.The rusults show that without catalyst,methyl formate completed oxidition at 600 K-800 K under the 6.67%oxygen concentration.?-Al2O3 achieved great catalytic effects,it can make methyl formate complete catalytic oxidation in the range of 450 K-700 K.As for methyl tert-butyl ether,it is oxidation in the range of 500 K-1000 K.The experimental results illustrated that the AlON catalyst can be used to treat methyl tert-butyl ether in 10%oxygen environment.The catalytic decomposition interval is 370 K-620 K,which can meet the requirements of the actual ship exhaust gas outlet temperature.