Well-defined lanthanum ethylenediaminetetraacetates as the precursors of catalysts for the oxidative coupling of methane

• Water-soluble MOF was constructed by lanthanide ethylenediaminetetraacetate with chloride.
• Lanthanum chloride, nitrate and sulfate were converted to pure LaOCl, La2O2CO3 and La2O2SO4 or their mixtures respectively.
• Thermal decomposition products demonstrate good catalytic performances for the oxidative coupling reaction of methane (OCM).

Water-soluble metal organic framework (MOF) complex [La5Cl2(edta)3(H2O)18]nCln·8nH2O (1) is converted to its nitrate or sulfate derivatives [La2(NO3)2(edta)(H2O)5]n·3nH2O (2), [La2(SO4)(edta)(H2O)3]n (3) (H4edta = C10H16N2O8, ethylenediaminetetraacetic acid). The three well-defined complexes are further calcinated for the preparations of pure lanthanum oxides LaOCl, La2O2CO3 and La2O2SO4 or their mixtures respectively. The oxides from 1 to 2 show good catalytic performances for the oxidative coupling reaction of methane (OCM). Their conversions of methane and the selectivities to C2 achieved 24.5%, 39.2% and 28.0%, 47.4% respectively at low temperature 550 °C, while the pure La2O2SO4 from 3 is not active at low temperature. The latter is contradict to the result by simple treatment of La2(SO4)3 reported previously.

Thermal products of [La5Cl2(edta)3(H2O)18]nCln·8nH2O (1) and [La2(NO3)2(edta)(H2O)5]n·3nH2O (2), demonstrate good catalytic performances for the oxidative coupling reaction of methane (OCM). While La2O2SO4 from [La2(SO4)(edta)(H2O)3]n (3) is not active at low temperature.Figure optionsDownload as PowerPoint slide