EMT-type zeolite for deep purification of trace polar-oxygenated compounds from light olefins

Abstract

Pure EMT-type zeolite (EMC-2) was synthesized using 18-crown-6 ether as structure direction agent and first applied for deeply purification the trace polar-oxygenated compounds from light olefins as well as studying the removal mechanism. This EMC-2 zeolite crystals exhibited high crystallinity, regular hexagonal platelet morphology mainly with diameter of 3–4 μm, thickness of 350 nm. The N2 adsorption/desorption analyzer indicated the EMC-2 zeolite had both micropores and inter-particle mesopores. The BET surface area, total pore volume and average pore size were 599.5 m2/g, 0.347 cm3/g and 2.32 nm, respectively. By dynamic adsorption experiment at room temperature, the results demonstrated that the EMC-2 zeolite could deeply purify the trace polar-oxygenated compounds to below 1 × 10−6 mol/mol in N2 or C2H4 flow, and exhibited more excellent purification performance than that of 13X zeolite. The breakthrough time for methanol to 1.18 g EMC-2 zeolite was 73.0 h in N2 system, and 6.0 h to 0.31 g EMC-2 zeolite in C2H4 system. The cumulative adsorption amounts of EMC-2 zeolite for methanol and propanal in N2 and C2H4 system were 55.99 mg/g, 113.93 mg/g and 98.17 mg/g, 171.61 mg/g, respectively. Moreover, the regeneration experiment also demonstrated the EMC-2 zeolite had more stable structure and longer lifetime. The in-situ FTIR spectra indicated both the purification processes of EMC-2 zeolite for methanol and propanal were physi-sorption mainly via the interaction between the oxygen lone-pair electrons of impurities and the Na+ of EMC-2 zeolite. Therefore, the EMC-2 zeolite had great potentials for future industrial application of trace polar-oxygenated compounds removal from light olefins.