Abstract：The ultrasonic extraction technique with CH2Cl2 as solvent was introduced to extract the soluble coking deposited on external surface of zeolite pores in methanol to olefin (MTO) spent and partially regenerated catalyst. Then HF acid was used to dissolve the coking catalyst to release the internal coking, followed by neutralization with Na2CO3 solution and extraction with CH2Cl2, to extract the coking in the pores of zeolite in MTO spent and partially regenerated catalyst. The composition and distribution of the organic compounds were analyzed and identified by gas chromatgraphy-mass spectrometer(GC-MS), the mechanism of coking formation on MTO catalysts and the mechanism of regeneration were analyzed and discussed as well. The results showed that the soluble coking on external surface were mainly saturated hydrocarbons (nC23-nC31 accounted for most part) and a small amount of aromatic hydrocarbons with one or two benzene rings. The soluble coking adsorbed in the zeolite pores mainly were aromatic hydrocarbons (3-4 benzene rings), which accounted for about 80% according to the peak intensity in GC-MS, phenanthrene and pyrene accounted for about 50% of the total. While for the MTO regenerated catalyst, the species adsorbed on external surface were mainly saturated hydrocarbons with high boiling points (nC23-n C31 account for most part), and the species in zeolite pores were mainly the residual of high content coking, such as pyrene and phenanthrene. The saturated hydrocarbons on external surface of catalysts were derived from polymerization of small molecule olefins. The aromatic hydrocarbons with one or two benzene rings on external surface were formed in the zeolite pores, then spilled and adsorbed outside the pores. The aromatic hydrocarbons in the pores of zeolite were derived from a series of reactions, including oligomerization, hydrogen transfer, cyclization and dehydrogenation.
