Abstract:

The modification effect of oxalic acid solution treatment on SAPO-34 molecular sieve was studied by means of XRD,SEM,N₂ physisorption,XRF,ICP-AES,NH₃-TPD,FT-IR,solid NMR and fixed-bed methanol to olefins（MTO） reaction performance evaluation.Results showed that,treating SAPO-34 molecular sieve with oxalic acid solution can produce macropores in the crystalsvia skeleton etching,and consequently adjust the pore structure and micropore diffusivity.Meanwhile,the acid treatment can also selectively reduce the framework Si content,and consequently decrease the acid strength and surface acid site concentrationof SAPO-34 molecular sieve.These modification effects of the oxalic acid solution treatment can notably improve the anti-coking deactivation ability of SAPO-34 catalyst in MTO reaction.Therefore,the oxalic acid solution treatment is a method worth studying for the modification of SAPO-34 molecular sieve and the preparation of MTO catalyst.

Key words: SAPO-34 molecular sieve, oxalic acid solution treatment, MTO reaction