Study On The Catalyst Properties Of Methane Partial Oxidation Under Mild Conditions

Natural gas is considered to be a major energy and chemical raw material whichwould probably replace the coal and oil in the21th century. Its storage is abundant,and the consumption increase rapidly. Most of the natural gas storages are located inremote areas and on the seafloor, which leads to a higher cost for long distancetransportation of the gas. Due to high cost of transportation, the oilfield associated gasis usually treated by buring directly, which could cause the waste of energy andemission of CO2. Transformation of natural gas to liquid fuel such as methanol is agreat attractive way of making full use of natural gas from remote areas and oilfieldassociated.At present, the directly catalytic oxidation of methane to methanol isimplemented by gas-solid multiphase catalytic oxidation and aqueous catalyticoxidation, but these methods are difficult to be applied in large-scale industry. Theconversion and selectivity can not be improved at the same time for gas-solidmultiphase catalytic oxidation, while strong acid used in the aqueous catalyticoxidation could cause the equipment corrosion.The methane partial oxidation reaction in an aqueous medium by the catalytic ofmetal loaded zeolite with an oxidant of H2O2is carried out in this thesis. And theattempt to develop a new type of liquid phase catalytic reaction medium is made.In order to develop a methane oxidation catalyst at low temperature in aqueousmedium, Fe/ZSM-5and Fe-Cu/ZSM-5catalysts by liquid ion exchange method areprepared. And the structures and surface load conditions of them by SEM, BET, ICP,XRD and XPS methods are analyzed. Meanwhile the catalytic performance of themethane oxidation reaction in low temperature in an aqueous medium are studied.(1) In the catalyt of Fe/ZSM-5, the active component Fe, is highly dispersed onthe surface or enters into the pores of HZSM-5as Fe2O3. When the concentration offerric nitrate is0.015M, the corresponding capacity of Fe is1.51%. After oncereaction, there is a small amount of loss of Fe. Under the50℃of reactiontemperature,0.1g of Fe-Cu/ZSM-5,30bar of methane pressure,0.03mol of H2O2solvent,3h of reaction time,500rpm of stirring speed, the methane conversion rate is2.28%, and the production of methanol yield is33.20μmol.(2) Fe and Cu are co-loaded on HZSM-5. And they are highly dispersed on thesurface of HZSM-5or enter into the pores of HZSM-5as Fe2O3and CuO, respectively. The capacities of Fe and Cu are1.05%and0.92%, corresponding to0.015M of ferric nitrate and0.01M of copper nitrate, respectively. Under theoptimized reaction conditions, methane conversion rate is2.31%and the yield ofmethanol is85.59μmol. This indicates that the loading of Fe is contributed to theactivation of methane in the process of methane conversion by Fe-Cu/ZSM-5, but thisis also accompanied by the depth oxidation of methanol. The loading of Cu do notinfluence the activity of methane conversion obviously, but this way improves theselectivity of methanol. The co-loading of Fe and Cu make significantly improvementin methanol yield and methane conversion.