Product selectivity in methanol to hydrocarbon conversion for isostructural compositions of AFI and CHA molecular sieves

Isostructural molecular sieves based upon AlPO4 and SiO2 chemistry were made for comparison of catalytic selectivity. The AFI and CHA structures were compared with B and Al substitution of SiO2 and Mg and Si substitution in the AlPO4 case. The conversion of methanol to hydrocarbons was studied. Materials were characterized for acidity by NH3 TPD and NH3 microcalorimetry. Methanol conversion was carried out with products analyzed by GC-MS and spent catalysts by 13C MAS NMR. Borosilicate sieves have acidity too low to carry out this catalytic transformation. Other substituting components were successful but product selectivity seemed to be governed by geometric features of the sieves, rather than by variable acidity due to different types of lattice substitution. Products from small pore molecular sieves SAPO-34 and SSZ-13 were largely olefinic and comprised of C5 and smaller. The large pore sieves, SAPO-5, MAPO-5, and SSZ-24, all produced aromatic-rich products. A considerable quantity of the recovered hydrocarbon was incorporated into penta- and hexamethylbenzene.

[1]  S. W. Kaiser.  Methanol conversion to light olefins over silicoaluminophosphate molecular sieves , 1985 .

[2]  R. Gorte,et al.  An examination of the acid sites in SAPO-5 , 1991 .

[3]  H. Pfeifer,et al.  On the Correlation between the 1H NMR Chemical Shift and the Stretching Vibration Frequency of Hydroxyl Groups in Solids , 1992 .

[4]  Ronghui Wang,et al.  CHARACTERISTICS AND PERFORMANCE OF SAPO-34 CATALYST FOR METHANOL-TO-OLEFIN CONVERSION , 1990 .

[5]  D. Bibby,et al.  Sorption studies of coke deposited on ZSM-5 , 1989 .

[6]  Kazuhiro Kato,et al.  Mordenite with long life and selectivity for methanol conversion to gasoline: mordenite modified by barium ion exchange, dealumination and chemical vapor deposition of silicon methoxide , 1990 .

[7]  G. Froment,et al.  Catalytic conversion of methanol to light alkenes on SAPO molecular sieves , 1991 .

[8]  G. Hutchings,et al.  Methanol conversion to hydrocarbons: investigation of the possible role of carbon monoxide in the formation of the initial carbon-carbon bond , 1990 .

[9]  P. Grobet.  Innovation in Zeolite Materials Science , 1988 .

[10]  O. Kikhtyanin,et al.  Study of catalytic properties of aluminophosphates with different phase compositions , 1990 .

[11]  P. J. O'malley,et al.  Synthesis and properties of SAPO-5 molecular sieves. Silicon incorporation into the framework , 1992 .

[12]  H. Pfeifer,et al.  Multinuclear NMR and catalytic investigations of deactivation of zeolite H-ZSM-5 , 1990 .

[13]  Brent M. T. Lok,et al.  Aluminophosphate molecular sieves: a new class of microporous crystalline inorganic solids , 1982 .

[14]  C. Guéguen,et al.  Characterization of acid catalysts by means of model reactions: I. Acid strength necessary for the catalysis of various hydrocarbon reactions , 1990 .

[15]  S. Zones.  Direct hydrothermal conversion of cubic P zeolite to organozeolite SSZ-13 , 1990 .