Fig.1

In situ solid-state 13C MAS NMR spectra recorded during 13C-methanol conversion over H-ZSM-5 at 300 ℃[38]

Fig.2

(a) In situ solid-state 13C MAS NMR spectra of continuous-flow 13C-methanol conversion over H-SSZ-13 catalyst at 220 ℃; (b) The 13C CP/MAS NMR and (c) 2D 13C-13C CORD (COmbined R2 Driven) spin diffusion MAS NMR spectra of in situ 13C-methanol conversion over H-SSZ-13 catalyst at 220 ℃ for 30 min[39]

Fig.3

Catalytic cycles of the paring and side-chain reaction mechanisms for the MTO conversion with the involvement of pentaMCP+ and heptaMB + in H-SSZ-13 zeolite[5]

Fig.4

(a) In situ 13C MAS NMR spectra of 13CH3OH reaction over H-SSZ-13 catalyst at 275 ℃, the characteristic signals at 154 and 245 ppm illustrate the formation of pentamethylcyclopentenyl cation (PMCP+), 0~40 ppm are assigned to the paraffin; (b) ① The initial ethene is generated from methanol by direct mechanism; ② MCP species are produced from initial ethene; ③ PMBs species are produced from the co-reaction of MCP species and methanol; ④ The olefins are formed via indirect mechanism including of aromatics-based, alkenes-based, and cyclopentadienes based cycles[47]

Fig.5

DNP enhanced 2D 13C-13C refocused INADEQUATE spectrum of activated M-β[48]

Fig.6

(a~c) 1H PFG NMR signals decay with linearly increasing gradient magnetic field strength in 16 steps for SAPO-35 (a), SAPO-34 (b) and DNL-6 (c) measured at 298 K. (d~f) The corresponding spin echo attention of PFG NMR on the log-linear scale for SAPO-35 (d), SAPO-34 (e) and DNL-6 (f) measured at 298 K. (g) The self-diffusion coefficients of methane acquired by PFG NMR and MD; (h) The loading dependence of experimental and simulated self-diffusion coefficients for methane; (i) The temperature dependence of self-diffusion coefficients for methane[68]

Fig.7

2D EXSY NMR spectra of xenon adsorbed in the SAPO-34 molecular sieve with an average loading of 3.6 xenon atoms per cage at 298 K with mixing times of (a) 1 ms, (b) 2 ms, and (c) 10 ms, respectively; (d) Possible spatial location of Xen clusters in a single SAPO-34 crystal[82]

Fig.8

(a) Loading-dependent 129Xe NMR spectra of DNL-6 molecule sieves obtained at 298 K; (b) 129Xe NMR chemical shift of adsorbed xenon as the xenon loading increases[83]

Fig.9

Shape selectivity in the methanol-to-olefins process over cavity-type molecular sieves with 8-MR windows: (a) Cavity-controlled diffusion; (b) Critical intermediates formation; (c) Product generation in the MTO process[68]

Fig.10

The variation in intracrystalline (a) self-diffusion coefficients and (b) diffusion activation energies of CH4 and C2H4 in flesh and spent SAPO-34 as a function of coke amount, respectively[25]