CH3OH CONVERSION IN DIMETHYL ETHER ON POROUS AND AMORPHOUS ALUMINA GELS OF HIGH-SURFACE-AREA

A microporous, amorphous alumina gel was prepared in an anhydrous medi um using methanol as solvent, a macroporous alumina aerogel was synthe sized from sec Al-butoxide by the autoclave method. They showed surfac e areas > 400 m2/g and a very high catalytic activity towards dimethyl ether (DME) formation from CH3OH, between 205 and 250-degrees-C in di fferential flow conditions. Their selectivities in DME were 100% and t heir activities were very stable with time on stream. The true activat ion energy was found to be 16-17 kcal/mol. The kinetics follows a vari able order law with respect to methanol, showing a zero order for high methanol pressures. Their acidity compares well with that of gamma-al umina.