Zeolite Rho Loaded with Methylamines. III. Trimethylamine Loadings

Samples of two differently prepared zeolites rho loaded with different amounts of trimethylamine (TMA) were studied in their hydrated and dehydrated forms by X-ray and neutron diffraction experiments. Both zeolites are partially dealuminated, as indicated by nonframework Al, which is assumed to be Al₂O₃ or AlOOH. Series I was prepared from dry-calcined NHn-rho at 873 K, series II from steam-calcined NHn-rho at 773 K. The samples were loaded with different amounts of deuterated TMA. Rietveld refinements yielded the following results for series I: (1) H_3.8(H-TMA)₅Cs_0.2Al₉ Si₃₉O96.Al₂O₃.22H₂O, X-ray data collection at room temperature, Imm, a = 15.0542 (2) Å, R_wp = 0.094; (2) composition as in (1) (anhydrous), neutron data collection at 5 K of dehydrated and deuterated sample, Im3m, a = 15.0467 (4) Å, R_wp = 0.034. Series II: (3) H_0.3(H-TMA)₅Cs_0.7Al₆Si₄₂O₉₆.2.5Al₂O₃.22H₂O, X-ray data collection at room temperature, Imm, a = 15.0574 (2) Å, R_wp = 0.118; (4) composition as in (3) (anhydrous), neutron data collection at 5 K of dehydrated and deuterated sample, lmm, a = 15.0761 (5) Å, R_wp = 0.037. In all determinations the TMA molecules reside with the N and H (D in neutron diffraction analysis) atoms on the central axes (x, 0, 0) pointing towards the center of the single eight-ring, whilst the three methyl groups point away to the center of the -cage.